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Claims  |
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What is claimed is:
1. A filter for fluid, comprising:
a plurality of one-piece annular support members each of which includes an
annular boss section having a central opening, an annular outer frame
section, and an intermediate section radially outwardly extending between
said boss section and said outer frame section, said plurality of support
members including first and second support members, said first support
member being located above said second support member;
means for securely disposing said support members one upon another in a
manner that the central openings of said support members are axially
aligned with each other;
means defining a plurality of curved and winding continuous ridges in said
intermediate section on upper and lower sides of said support member, each
of said ridges projecting axially from surface of base of said
intermediate section to form a land, each ridge extending generally
radially and having a first end extending toward said outer frame section,
and a second end extending toward said boss section so as to form an
elongate groove between adjacent said ridges, said elongate groove
continuing to the center opening of said boss section, said ridges
including ridges each having a plurality of arcuate segments generally
parallel with each other, and a plurality of rounded segments each
connecting the adjacent arcuate segments to form a generally C-shaped
segment;
porous filter membranes each sealingly covering at least said support
member intermediate section, each filter membrane defining on opposite
sides thereof a dirty side and a clean side on which said intermediate
section is positioned, said filter membrane including first and second
annular filter membranes, said first filter membrane covering said
intermediate section on the lower side of said first support member, said
second filter membrane covering said intermediate section on the upper
side of said second support member, said first filter membrane having an
outer peripheral section hermetically sealed to said first support member
outer frame, and an inner peripheral section, said second filter membrane
having an outer peripheral section hermetically sealed to said second
support member outer frame section, and an inner peripheral section
hermetically sealed to the first filter membrane inner peripheral section;
and
means for causing fluid flow from said dirty side to said clean side so
that fluid pressure is applied to press said membrane onto said ridges.
2. A filter as claimed in claim 1, wherein said support member boss section
is formed with a plurality of first cut-out grooves each of which axially
extends from lower surface of said boss section, each first cut-out groove
communicating with the boss section central opening and continuous to each
elongate groove in said intermediate section.
3. A filter as claimed in claim 2, further comprising means defining a
first through-hole formed in said elongate groove in a manner to
communicate said elongate groove on the upper side with said elongate
groove on the lower side of said support member.
4. A filter as claimed in claim 3, wherein said corresponding curved ridges
on the upper and lower sides are located symmetrical with respect to a
central plane of said intermediate section which plane is parallel with
the base surface of said intermediate section.
5. A filter as claimed in claim 4, wherein said curved ridges include first
winding elongate ridges each having a first end connected to said outer
frame section and a second end located in the vicinity of and separate
from said boss section, and second winding elongate ridges each having a
first end connected to said outer frame section and a second end connected
to said boss section, wherein first and second elongate grooves are formed
on opposite sides of each first winding elongate edge and joined to each
other to be continuous to the central opening of said boss section,
wherein said first through-hole is located in said first elongate groove
on the upper and lower sides of said support member.
6. A filter as claimed in claim 5, further comprising means defining a
second through-hole formed in said second elongate groove on the upper and
lower sides of said support member.
7. A filter as claimed in claim 5, wherein said first winding elongate
ridge is smaller in range of width of winding than said second winding
elongate ridge.
8. A filter as claimed in claim 4, further comprising means defining a
second through-hole formed in said elongate groove and located adjacent
said first through-hole, said second through-hole communicating said
elongate grooves on the upper and lower sides of said support member.
9. A filter as claimed in claim 2, wherein said support member boss section
is formed with a plurality of second cut-out grooves each of which extends
from upper surface of said boss section, each second cut-out groove
communicating with the boss section central opening and continuous to each
elongate groove only on the upper side of said support member, wherein
each first cut-out groove is continuous to each elongate groove only on
the lower side of the support member.
10. A filter as claimed in claim 9, wherein said curved ridge on the upper
side and said curved ridge on the lower side shift from each other in a
circumferential direction of said support member.
11. A filter as claimed in claim 1, further comprising an upper end plate
located adjacent said support member at an upper-most position, and a
lower end plate located adjacent said support member at a lower-most
position, wherein said support members, said filter membranes and said
upper and lower end plates constituting a filter element.
12. A filter as claimed in claim 11, further comprising a casing inside
which said filter element is disposed, said casing being formed at its
inner bottom wall with ribs.
13. A filter as claimed in claim 12, further comprising a spacer member
fixedly interposed between said lower end plate and said ribs.
14. A filter as claimed in claim 13, wherein said ribs extend radially
inwardly from inner wall of said casing and having respective inner ends
which are separate from each other to define a central space communicated
with a fluid inlet of the casing through which fluid to be filtered enters
inside of said casing.
15. A filter as claimed in claim 14, wherein said spacer member includes an
annular flange section having a predetermined thickness and positioned
between said lower end plate and said ribs, and a cylindrical section
positioned in said central space defined by the rib inner ends.
16. A filter as claimed in claim 14, wherein said lower end plate includes
an annular projection in contact with said ribs, said annular projection
projecting axially downwardly to be in contact with said ribs.
17. A filter as claimed in claim 11, further comprising a casing inside
which said filter element is disposed, wherein said upper end plate
includes a plurality of projections formed at an outer peripheral section
of said upper end plate, said projections being in contact with an inner
wall of said casing in a manner to prevent upward deformation of said
upper end plate.
18. A filter as claimed in claim 17, wherein said projections extend
radially outwardly to be located below and in contact with an annular
section inwardly projecting from the inner wall of said casing.
19. A filter as claimed in claim 18, wherein said upper end plate is formed
at the outer peripheral section with a plurality of grooves each extending
radially inwardly to form a space between said upper end plate and said
annular section.
20. A filter as claimed in claim 17, wherein said projections extend
axially upwardly to be in contact with the inner wall of said casing.
21. A filter as claimed in claim 17, wherein said casing includes an air
vent pipe through which gas within said casing is able to be vented out of
said casing, said air vent pipe being located over said upper end plate.
22. A filter as claimed in claim 1, wherein said curved ridges include
first winding elongate ridges each having a first end connected to said
outer frame and a second end connected to said boss section, and second
winding elongate ridges each having a first end connected to said outer
frame and a second end located in the vicinity of and separate from said
boss section.
23. A filter as claimed in claim 22, wherein each first winding elongate
ridge is smaller in range of width of winding than each second winding
elongate ridge.
24. A filter as claimed in claim 22, wherein first and second elongate
grooves are formed on opposite sides of said second winding elongate
ridge, said first and second elongate grooves being joined with each other
at a location in the vicinity of said boss section and continuous to the
boss section central opening.
25. A filter as claimed in claim 1, wherein each support member is
disc-shaped and of one-piece structure.
26. A filter as claimed in claim 1, wherein level of top of each ridge is
equal to or axially inside that of said boss section.
27. A filter as claimed in claim 1, wherein said support members are so
disposed that said boss sections of adjacent said support members are in
contact with each other.
28. A filter as claimed in claim 1, wherein said curved ridges include at
least curved ridges each of which has a first end connected to said outer
frame section, and a second end connected to said boss section.
29. A support member for a filter element, comprising:
a plurality of one-piece annular support members each of which includes an
annular boss section having a central opening, an annular outer frame
section, and an intermediate section radially outwardly extending between
said boss section and said outer frame section, said plurality of support
members including first and second support members, said first support
member being located above said second support member;
means for securely disposing said support members one upon another in a
manner that the central openings of said support members are axially
aligned with each other;
means defining a plurality of curved and winding continuous ridges in said
intermediate section on upper and lower sides of said support member, each
of said ridges projecting axially from surface of base of said
intermediate section to form a land, each ridge extending generally
radially and having a first end extending toward said outer frame section,
and a second end extending toward said boss section so as to form an
elongate groove between adjacent said ridges, said elongate groove
continuing to the central opening of said boss section, said ridges
including ridges each having a plurality of arcuate segments generally
parallel with each other, and a plurality of rounded segments each
connecting the adjacent arcuate segments to form a generally C-shaped
segment;
porous filter membranes each sealingly covering at least said support
member intermediate section, each filter membrane defining on opposite
sides thereof a dirty side and a clean side on which said intermediate
section is positioned, said filter membrane including first and second
annular filter membranes, said first filter membrane covering said
intermediate section on the lower side of said first support member, said
second filter membrane covering said intermediate section on the upper
side of said second support member, said first filter membrane having an
outer peripheral section hermetically sealed to said first support member
outer frame, and an inner peripheral section, said second filter membrane
having an outer peripheral section hermetically sealed to said second
support member outer frame section, and an inner peripheral section
hermetically sealed to the first filter membrane inner peripheral section;
and
means for causing fluid to flow from said dirty side to said clean side so
that fluid pressure is applied to press said membrane onto said ridges.
30. A support member for a filter membrane in use for a filter, comprising:
an annular boss section having a central opening;
an annular outer frame section;
an intermediate section radially outwardly extending between said boss
section and said outer frame section, the filter membrane being
supportable on said intermediate section; and
means defining a plurality of curved and winding continuous ridges in said
intermediate section on upper and lower sides of said support member, each
of said curved ridges projecting axially from surface of base of said
intermediate section to form a land, each ridge extending generally
radially and having a first end extending toward said outer frame section,
and a second end extending toward said boss section so as to form an
elongate groove between adjacent said ridges, said elongate groove
continuing to the central opening of said boss section, said ridges
including ridges each having a plurality of arcuate segments generally
parallel with each other, and a plurality of rounded segments each
connecting the adjacent arcuate segments to form a generally C-shaped
segment. |
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Claims |
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Description |
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BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to a submicron disc filter in use
for filtering various chemicals, pure water and various gases, and more
particularly to an improvement in such a submicron disc filter having a
filter element constituted by superposing a plurality of filter units each
including a support member and filter membranes.
2. Description of the Prior Art
In connection with filtering various pharmaceuticals, chemicals and gases
in use for production of electronic parts, and pure water used in food
industry, such filters are required to have chemical-resistance,
heat-resistance, and a filter precision of submicron order. Accordingly, a
variety of submicron disc filters for such ultrafiltration have been
proposed and used. One of such submicron disc filters is configured as
follows: The filter consists of a filter element housed in a casing. The
filter element includes a plurality of superposed filter units. The filter
unit is constructed of a disc-type annular support member whose major
parts on its both sides or surfaces are covered with porous filter
membranes for ultrafiltration. Each support member is constructed of upper
and lower counterparts which are secured to each other. Each counterpart
is of the type of a grid to support the filter membrane thereon.
Additionally, fluid flow passages are formed between the upper and lower
counterparts so that filtrate after filtration with the filter membrane
flows along the fluid flow passages to an axial fluid flow passage formed
axially in the filter element.
However, in such a submicron disc filter of the above-mentioned
construction, the structure of each support member for the filter
membranes is considerably complicated and therefore difficult to produce.
In this connection, high precision is required in production of the
support member counterpart because the two support member counterparts are
fitted with each other to form a support member. Additionally, such a
structure unavoidably inceases the thickness of each support member, so
that it is difficult to increase the number of filter units of the filter
element in a casing having a limited volume. This makes it difficult to
increase the filtering area of the filter element, thereby allowing
pressure drop increase and filter life shortening. Furthermore, since the
surface of the support member is grid-shaped, angular corners and edges
tend to be formed on the support member surface on which the considerably
thin and soft filter membrane is supported receiving fluid pressure of the
fluid to be filtered. Accordingly, when a high fluid pressure acts on the
filter membrane particularly in th event that clogging proceeds,
concentrated stress is generated at the angular corners and edges, thereby
stretching the filter membrane to enlarge the pore size thereof or to tear
the filter membrane.
SUMMARY OF THE INVENTION
A precision filter of the present invention consists of a plurality of
annular support members for a filter membrane. Each support member
includes an annular boss section having a central opening, an annular
outer frame section, and an intermediate section radially outwardly
extending between the boss section and the outer frame section. The
annular support members are disposed one upon another in such a manner
that the central openings of the support members are axially aligned with
each other. The intermediate section of the support member is formed with
a plurality of curved ridges lying on the upper and lower sides of the
support member. The curved ridge projects axially from the surface of the
base of the intermediate section to form a land. The curved ridge has a
first end connected to the outer frame section and a second end connected
to the boss section so as to form an elongate groove continuing to the
center opening of the boss section. The porous filter membrane sealingly
covers at least the support member intermediate section so as to define on
the opposite sides thereof a dirty side and a clean side on which the
intermediate section is positioned.
Accordingly, the structure of each support member for the filter membrane
is very simple and therefore easy to produce. such a simple structure of
the support member minimizes the thickness of the support member, thereby
increasing the number of the support members housed in a casing having a
limited volume. Consequently, the filtering area is increased thereby to
decrease pressure drop and prolong filter life. Furthermore, no angular
corner and edge are formed on the surface of the support member and
therefore the filter membrane is prevented from its pore size enlargement
and tearing.
BRIEF DESCRIPTION OF THE DRAWINGS
The features and advantages of the submicron disc filter according to the
present invention will be more clearly appreciated from the following
description taken in conjunction with the accompanying drawings in which
like reference numerals designate corresponding elements and parts, and in
which:
FIG. 1 is a vertical sectional view of a first embodiment of a submicron
disc filter according to the present invention;
FIG. 2A is a fragmentary plan view of each support member for a filter
membrane, of the filter of FIG. 1;
FIG. 2B is a sectional view taken in the direction of arrows substantially
along the line 2B--2B of FIG. 2A;
FIG. 3 is a vertical sectional view of a second embodiment of the submicron
disc filter according to the present invention;
FIG. 4 is a perspective view of a spacer used in the filter of FIG. 3;
FIG. 5 is a fragmentary vertical sectional view of a modified example of
the second embodiment submicron disc filter;
FIG. 6 is a vertical sectional view of a third embodiment of the submicron
disc filter according to the present invention;
FIG. 7 is a fragmentary perspective enlarged view of an essential part of
the filter of FIG. 6;
FIG. 8A is a fragmentary vertical sectional view of a fourth embodiment of
the submicron disc filter according to the present invention;
FIG. 8B is a perspective view of an upper end plate of the filter of FIG.
8A;
FIG. 9 is a vertical sectional view of a fifth embodiment of the submicron
disc filter according to the present invention;
FIG. 10 is a plan view of a support member of the filter of FIG. 9,
illustrated as two divided parts;
FIG. 11 is a fragmentary plan view of a support member as viewed from the
reverse side thereof;
FIG. 12 is a sectional view taken in the direction of arrows substantially
along the line 12--12 of FIG. 11;
FIG. 13 is an enlarged sectional view taken in the direction of arrows
substantially along the line 13--13 of FIG. 11; and
FIG. 14 is a fragmentary plan view similar to FIG. 11 but showing a sixth
embodiment of the submicron disc filter according to the present invention
.
DETAILED DESCRIPTION OF THE INVENTION
Referring now to FIGS. 1, 2A and 2B, a preferred embodiment of a submicron
disc filter according to the present invention is illustrated. The filter
consists of a filter element 1 which includes a plurality of annular
support members 2. Each support member 2 is made of a chemical-resistant
and heat-resistant plastic such as ethylene tetrafluoride, polypropylene
or nylon. The support member 2 is formed as a one-piece and includes an
annular boss section 3, an annular outer frame 5, and an annular
intermediate section 4 which extends radially outwardly so as to
integrally connect the boss section 3 and the outer frame 5. The support
members 2 are superposed one upon another in such a manner that the boss
sections 3 of the adjacent support members 2 are in sealing contact with
each other. Accordingly, the successive central openings 3a of the boss
sections 3 of the superposed support members 2 form an axial fluid flow
passage. Additionally, upper and lower end plates 6a, 6b are so disposed
as to contact with the boss sections 3, 3 of the upper-most and lower-most
support members 2, 2, respectively.
Upper and lower annular porous filter membranes 7a, 7b are disposed to
cover the upper and lower sides of the intermediate section 4 of each
support member 2, maintaining fluid-tight seal. The filter membrane 7a, 7b
is made of a plastic such as ethylene tetrafluoride. More specifically,
the outer peripheral section of the upper filter membrane 7a is secured to
the upper surface of the outer frame section 5 of each support member 2 by
welding, whereas the inner peripheral section of the upper filter membrane
7a is secured to the inner peripheral section of the lower filter membrane
7b for the support member 2 located upon the above-mentioned support
member 2 by welding as shown in FIG. 1. The filter membrane 7a, 7b defines
outside a dirty side where fluid to be filtered flows, and inside a clean
side where filtrate flows. Thus, the support member 2 and upper and lower
filter membranes 7a, 7b constitute a filter unit (not identified). The
inner peripheral portion of the upper filter membrane 7a for the
upper-most support member 2 is secured to the upper end plate 6a by
welding. Similarly, the inner peripheral portion of the lower filter
membrane 7b for the lower-most support member 2 is secured to the lower
end plate 6b by welding though not shown. The thus configured filter
element 1 is fixedly disposed within a casing 10 by fixing the filter
element 1 with a center bolt 8. The center bolt 8 is screwed into a
threaded filtrate outlet 10b formed through a boss section of the casing
10, in which a head 8a of the bolt 8 is in contact with the lower end
plate 6b. The center bolt 8 is formed with an axial groove (not shown) to
establish fluid communication between the axial fluid passage and the
outside of the casing 10 via the filtrate outlet 10b. An inlet 10a for
fluid to be filtered is formed in the casing 10 at a location in the
vicinity of the lower end plate 6b. It will be understood that the end
plates 6a, 6b, the center bolt 8 and the casing 10 may be made of a
plastic, the same as or similar to the support member 2.
As clearly shown in FIGS. 2A and 2B, a plurality of gently curving or
winding elongate ridges 4a and largely curving or winding elongate ridges
4b are formed in the upper side S.sub.1 of the intermediate section 4 of
the support member 2. Each ridge projects from the surface of base of the
intermediate section 4 to form a land, in which the level of the top of
each ridge 4a, 4b is equal to or axially inside the level of the upper or
lower surface of the outer frame 5. In other words, the level the top of
each ridge 4a, 4b does not project over the level of the upper or lower
surface of the outer frame 5. Each gently winding ridge 4a has an outer
end integrally connected with the outer frame 5 and an inner end
integrally connected with the boss section 3. Each largely winding ridge
4b has an outer end integrally connected with the outer frame 5 and an
inner end which is located near the boss section 3 but is not connected
with the boss section 3. A winding groove 4c is formed between each gently
winding ridge 4a and each largely winding ridge 4b. In other words, two
winding grooves 4c, 4c are formed on the opposite sides of the largely
winding ridge 4b, in which the two winding grooves 4c, 4c are joined with
each other at a location in the vicinity of the outer end of the largely
winding ridge 4b and continues to an upper cut-out groove 4a which axially
extends from the upper surface of the boss section 3 to an axially central
part of the boss section 3. The upper cut-out groove 3b radially extends
and communicates with or merges in the central opening 3a of the boss
section 3. As shown, each of the gently and largely winding elongate
ridges 4a, 4b extends generally radially. The gently winding ridge 4a has
a generally constant width of winding, whereas the largely winding ridge
4b has a width of winding which width increases in a radial direction of
from the boass section 3 toward the outer frame 5. The largely winding
ridges 4b has arcuate segments A which are generally parallel with each
other, in which the length of the arcuate segment A increases in the
direction of from the boss section 3 toward the outer frame 5. It is to be
noted that the adjacent arcuate segments A are integrally connected to
each other with a rounded segment B. It will be understood that the gently
and largely winding ridges 4a, 4b are located close to each other to
prevent the groove 4c from being widened.
Similarly to on the upper side S.sub.1 of the support member intermediate
section 4, a plurality of the gently and largely winding ridges 4a, 4b are
formed also on the lower side S.sub.2 of the support member intermediate
section 4 in the same manner as in the upper side S.sub.1 of the support
member intermediate section 4. However, the circumferential locations of
the corresponding ridge on the upper and lower sides S.sub.1, S.sub.2
shift or are different from each other as shown in FIG. 2B. The groove 4c
on the lower side S.sub.2 of the support member intermediate section 4
continues to the lower cut-out groove 3b which extends from the lower
surface of the boss section 3 to an axially central part of the boss
section 3. The lower cut-out groove 3b extends radially and communicates
with or merges in the central opening 3a of the boss section 3.
While only the gently and largely winding elongate ridges 4a, 4b have been
shown and described as ridges formed in the support member intermediate
section 4, it will be understood that other ridges having other shapes may
be employed in place of the ridges 4a, 4b, in which it is required that
the ridges include ridges connecting the boss section 3 and the outer
frame section 5 so as to narrow grooves continuing to the cut-out grooves
3b of the boss section 3. While the circumferential locations of the
corresponding ridges on the upper and lower sides S.sub.1, S.sub.2 of the
support member intermediate section 4 have been shown and described as
different from each other in the first embodiment, it will be appreciated
that the corresponding ridges on the upper and lower sides S.sub.1,
S.sub.2 are positioned at the same circumferential locations so that the
same or similar ridges may be located symmetrical with respect to a center
plane (not shown) of the intermediate section 4 which plane is parallel
with the base surface of the intermediate section.
With the thus configured submicron disc filter, the fluid (liquid) to be
filtered enters through the inlet 10a of the casing 10 and flows through
an annular space between the filter element 1 and the inner peripheral
surface of the casing 10. Then, the fluid passes through the filter
membranes 7a, 7b and enters the inside of the filter membranes, thereby
accomplishing precision filtering of the fluid. The thus-filtered fluid or
filtrate flows along the grooves 4c formed on the upper and lower sides
S.sub.1, S.sub.2 of the support member intermediate section 4 and reaches
to the central opening 3 of the boss section 3 or the axial fluid flow
passage. Thereafter, the fluid flows through the axial groove of the
center bolt 8 and the filtrate outlet 10b to be discharged out of the
casing 10.
As appreciated from the above, according to the thus configured submicron
disc filter, each support member 2 for the filter membrane can be produced
simply by forming curved and elongate grooves on both side surfaces
S.sub.1, S.sub.2 of a flat annular disc material. This may simplify the
production process of the support member even in the case of producing it
by injection moulding. Such a simple structure of the support member
contributes to minimizing the thickness of the support member, so that the
number of support members of the filter element can be increased even in a
casing having a limited volume. This increases filtering area of the
filter element, thus suppressing pressure drop at a lower value and
prolonging filter life. Furthermore, since the elongate ridges of the
support member are curved and rounded to prevent formation of angular
corners and edges on the surface of the support member on which the filter
membrane is supported, the filter membrane is prevented from receiving
concentrated stress even when high fluid pressure acts on the filter
membrane, thereby avoiding local stretching of the filter membrane. This
prevents pore size of the filter membrane from locally enlarging or the
filter membrane from tearing.
FIGS. 3 and 4 illustrate a second embodiment of the precision filter in
accordance with the present invention, which is similar to the first
embodiment with the exception that the filter element 1 is fixedly
disposed within the casing 10 by interposing a spacer 20 between the
filter element 1 and a plurality of radially disposed ribs 21 formed on
the bottom inner surface of the casing 10. In this embodiment, the casing
10 consists of a container section 10e and a cover section 10f which are
secured to each other by welding. The ribs 21 are disposed on and integral
with the inner bottom surface of the container section 10e in such a
manner as to be located around an extension of the fluid inlet (opening)
10a.
The spacer 20 includes an annular flange section 20a having a predetermined
thickness, and a support cylinder section 20b. As shown in FIG. 4, the
spacer 20 is so disposed that the support cylinder section 20b is located
inside of the radially arranged ribs 21 whereas the flange section 20a is
interposed between the upper face of the ribs 21 and the lower end plate
6b of the filter element 20 so that the flange section 20a urgingly
contacts with the lower end plate 6b. By virtue of this spacer 20, the
filter element 1 is biased upwardly so that the upper end plate 6a
urgingly contacts with a cylindrical section 10d formed inside the casing
cover section 10f. The cylindrical section 10d is aligned with the
filtrate outlet pipe 10c defining therein the outlet (opening) 10b. The
upper end plate 6a is secured to the cylindrical section 10d by welding.
The casing cover section 10f is provided with an air vent pipe 10g through
which air or gas within the casing 10 is vented.
With this arrangement, in the event that the filter element 1 constructed
of the superposed disc-type filter units cannot be housed in the casing 10
owing to scattering of thicknesses of the respective support members 2,
one or two filter units are removed and then the spacer having such a
flange thickness as to be able to maintain a suitable distance or space
between the adjacent filter units is selected and installed on the ribs
21. Otherwise, in the event that the whole height of the filter element 1
is too small so that the distance between the adjacent filter units is
enlarged when installed in position as it is, the spacer having such a
flange thickness as to avoid clearance enlargement is selected to be
installed on the ribs 21.
Accordingly, a suitable distance or space is maintained between the
adjacent filter units thereby avoiding abnormal tension applied to welded
parts of the filter membranes and abnormal expansion of the filter
membrane, even when fluid (liquid) enters the inside of the casing 10
through the inlet 10a so that a fluid pressure acts on the filter membrane
7a, 7b in a direction from the outside to the inside of the filter
membrane 7a, 7b during operation of the filter, or even when a fluid
pressure acts on the inner surface of the filter membrane from the inside
through the outlet 10b during stopping of operation of the filter. It will
be appreciated that, for the same purpose, the separate spacer 20 may not
be used in which the lower end plate 6b' is formed at its lower surface
with an annular projection 22 having a predetermined thickness as shown in
FIG. 5. The annular projection 22 is in contact with the upper surface of
the ribs 21. Additionally, the lower end plate 6b' is formed at the lower
surface with a cylindrical section 23 located among the ends of the ribs
21.
FIGS. 6 and 7 illustrate a third embodiment of the submicron disc filter
according to the present invention, which is similar to the second
embodiment of FIG. 3 with the exception that the spacer 20 is removed so
that the ribs 21 are in direct contact with the lower end plate 6b. In
this embodiment, the upper end plate 6a is formed at its outer periphery
with a plurality of projections 30 which project radially outwardly and
located at predetermined intervals. Additionally, the upper end plate 6a
is formed at its outer periphery with grooves 31 which extend radially
inwardly, each groove being located between the adjacent two projections
30. The projections 30 are in contact with an annular inner peripheral
portion P of the casing cover section 10f so that the outer peripheral
section of the upper end plate 6a is prevented from its upward
deformation.
With this arrangement, during operation of the filter, air within the
casing 10 is pushed upwardly through the grooves 31 and released through
the air vent pipe 10g to the outside of the casing 10. During stopping of
operation of the filter, a reverse fluid pressure acts on the inner
surface of the filter membranes 7a, 7b of the filter element 1 through the
filtrate outlet 10b connected to a fluid circuit so that the outer
peripheral section of each filter unit (or support member 2) will be
deformed upwardly; however, each filter unit is prevented from such
deformation because the upper end plate 6a is restrained by the casing
cover section 10f. Accordingly, the distance or space between the adjacent
filter units can be maintained constant, thereby preventing the filter
membrane from its inflation.
FIGS. 8A and 8B illustrate a fourth embodiment of the submicron disc filter
in accordance with the present invention, which is similar to the third
embodiment of FIGS. 6 and 7 except for the shape of the upper end plate
6a. In this embodiment, the upper end plate 6a is formed at its outer
peripheral section with four projections 32 located at prdetermined
intervals. Each projection 32 extends vertically upwardly from the upper
surface of the upper end plate 6a and adapted to be in contact with the
inner surface of the casing cover section 10f. Accordingly, with this
arrangement, the upper end plate 6a and the support members 2 are
prevented from their upward deformation like in the third embodiment.
Additionally, since the inner diameter of the upper end plate 6a is
considerably smaller than the inner diameter of the casing container
section, there arises no trouble in air venting at starting of operation
of filter.
FIGS. 9 to 13 illustrate a fifth embodiment of the precision filter in
accordance with the present invention, which is similar to the third
embodiment except for the shape of each support member 2 and the upper end
plate 6a. In this embodiment, each support member 2 is formed on both
sides S.sub.1, S.sub.2 of the intermediate section 4 with the largely
winding elongate ridges 4b' and the gently winding elongate ridges 4a'.
The corresponding ridges 4a' or 4b' on the upper and lower sides S.sub.1,
S.sub.2 are located symmetrical with respect to the central plane (not
identified) of the intermediate section 4 which plane is parallel with the
base surface of the intermediate section 4 as shown in FIG. 12. Each
largely winding elongate ridges 4b' has an outer end connected to or
integral with the outer frame 5 and an inner end connected to or integral
with the boss section 3, whereas each gently winding elongate ridge 4a'
has an outer end connected or integral with the outer frame 5 and an inner
end which is located in the vicinity of the boss section 3 and does not
connect to the boss section 3. As shown in FIG. 11, the inner end of each
gently winding ridge 4a' on the lower side S.sub.2 is located at the
entrance of the groove 3b of the boss section 3 in such a manner as not to
connect with the boss section 3. The winding groove 4c is formed between
the largely winding ridge 4b' and the gently winding ridge 4a' on the
upper and lower sides S.sub.1, S.sub.2 of the support member 2. It is to
be noted that the winding groove 4c is continuous to the cut-out groove 3b
of the boss section 3 only on the lower side S.sub.2, so that the winding
groove 4c on the upper side S.sub.1 does not continue to the cut-out
groove 3b on the upper side S.sub.1 as shown in FIG. 12.
As clearly shown in FIG. 11 and 13, two communication through-holes 40, 40
and the other two communication through-holes 40, 40 are respectively
located on the opposite sides of the gently winding groove 4c and in the
two winding grooves 4c, 4c between which the gently winding rdge 4a' is
located. The two through-holes 40, 40 are positioned in the vicinity of
the boss section 3. Each through-hole 40 passes through the base of the
intermediate section 4 to establish fluid communication between the
corresponding winding grooves 4c, 4c on the upper and lower sides S.sub.1,
S.sub.2 of the support member intermediate section 4, so that fluid
(liquid) flowing along the winding groove 4c on the upper side S.sub.1
flows through the through-hole 40 to the winding groove 4c on the lower
side S.sub.2 to reach to the cut-out groove 3b of the boass section 3 on
the lower side S.sub.2. It will be appreciated that the location,
cross-sectional area, and shape of each communication through-hole 40 may
be suitably selected in accordance with the flow rate of filtrate, the
shape of the winding ridges 4a', 4b' and the like.
In this embodiment, each support member 2 is formed at its outer periphery
with a plurality of spacer projections 41 each of which projects upwardly
over the level of the upper surface of the outer frame section 5 of the
support member 2 so that a suitable space is maintained between the
adjacent support members 2, 2.
With this embodiment, by virtue of the above-mentioned communication
through-holes 40, it is allowed to form the cut-out grooves 3b of the boss
section 3 only on the lower side S.sub.2 of the support member 2 thereby
to minimize the axial length or thickness of the boss section 3. This
increases the number of the superposed support members 2 even in the
casing 10 having a limited volume, thus enlarging filtering area.
FIG. 14 illustrates a sixth embodiment of the submicron disc filter
according to the present invention, similar to the fifth embodiment of
FIGS. 9 to 13. In this embodiment, only the largely winding elongate riges
4b' are formed on the both sides S.sub.1, S.sub.2 so that the winding
groove 4c is formed between the largely winding ridges 4b', 4b'. Only the
winding grooves 4b' on the lower side S.sub.2 continue respectively to the
cut-out grooves 3b of the boss section 3 because no cut-out groove 3b is
formed on the upper side S.sub.1 of the boss section 3. The two
communication through-holes 40, 40 are located in the winding groove 4c
and in the vicinity of boss section 3. Each through-hole 40 is formed
through the base of the intermediate section 4 in such a manner that fluid
(liquid) flowing along the winding groove 4c on the upper side S.sub.1
flows through the through-holes 40, 40 to the corresponding winding groove
4c on the lower side S.sub.2 to reach to the cut-out groove 3b of the boss
section 3 of the support member 2.
While at least one of the winding ridges 4a(4a'), 4b(4b') has been shown
and described as bein | | |
