Note: Descriptions are shown in the official language in which they were submitted.
This application is a division of Canadian Application No.
357,292 filed July 30, 1980 for a "Fluid Filter and
Indicator".
BACKGROUND OF THE INVENTION
This invention relates to fluid filters and more par-ticularly
to a hydraulic fluid filter having a differential pressure
indicator.
- Hydraulic filters of this type are commonly used as suction
line filters, return line filters and pressure filters as
well as in other configurations and it is conventional to
employ specific designs of the filter housing for each of
such applications.
In all these arrangements it is necessary from time to time
to replace the filter element and it is often desired to
accomplish such changeover without shutdown of the associated
fluid system. Further, each filter design must be efficient
in structure not only to achieve the results of adequate
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removal of particles of a particular size from the system
but also to achieve su~ficient dirt capacity in a convenient
housing structure along with a favorable fluid flow versus
pressure drop characteristic.
Still further in fluid filters of this type it is desirable
to have means for monitoring the condition of the filter
element to determine when the latter has become contaminated
and requires replacement.
It would be desirable to have a common filter structure which
is suitable for use in many of these different applications,
wherein servicing of the filter element may be accommodated
through either end of the filter housing or e~en from the
central portion thereof and wherein the typical filter
characteristics of quality of filtering are not sacrificed.
Further it is desirable as well to provide means for
indicating not only the condition of the filter element but
also the presence or absence of same in the filter housing,
with such indication provided either at the filter housing
or at a remote location.
2 0 SUMMARY OF THE INVENTION
-
A versatile filter structure is provided in a two-piece
housing consisting of a head casting and tubular filter
container wherein the filter element can be reached for
servicing through either end of the housing or alternatel~
at the central portion thereof when the head casting and
tubular housing are separated.
A unique diverter structure provides means for separating
the head casting into inlet and outlet partitions in
fluid communication respectiveIy ~ith the inner and outer
portions of a tubular filter eIement~ The diverter is in
9~3
a truncated funnel shaped configuration mounted at its
larger periphery within a cylindrical cavity in the head
casting and slidable therethrough together with the filter
element for replacement purposes. The diverter structure
provides an efficient means for transmitting fluid flow
between a transverse port of the housing and ~he axially
aligned filter element, and enhances the fluid flow versus
pressure drop characteristic of the filter. The smaller,
necked down end of the funnel-shaped di~erter serves to
direct fluid flow to the interior of the filter element and
further supports one end of the filter element within the
housing. An optionally removable end closuxe at the distal
end of the housing provides coaxial support for khe filter
` element and, further, optionally includes access ports to
the interior of the housing and may mount associated
valving devices.
The eliptical mounting edge of the diverter separates the
head casting into two chambers and this allows the convenience
of mounting an indicator on the exterior of the head casting
2Q with fluid access to t~e chambers across the edge of the
diverter element. A dual diaphragm arrangement supports a
piston for slidable movement in the indicator housing to
positions dictated by the fluid pressure differential to
provide visual or remote indications of the filter character-
istics. A compound spring arrangement is utilized to bias
- the piston and retains same at one end of the housing in the
absence of any fluid differential to provide an indication
of the absence of the filter element in the housing.
3RIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a longitudinal sectional view of a preferred
embodiment of the filter in an in-l~ne ported arrangement.
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Figure 2 is a simila~ longi.tudin~l sectional vie~ of anotherembodimen-t of the invention showing a filter with a
removable end closure member~
Figure 3 is a further similar sectional view oE a still
further embodiment of the lnvention showing a filter housing
ported for fluid flow through the remote end-of the housing.
Figure 4 is a view of a portion of the head casting of the
:: filter as viewed from the side of the inlet port showing
the indicator device mounted thereon.
Figure 5 is an enlarged sectional view of the indicator
device.
Figure 6 is a longitudinal sectional view of the snap-in
type poppet valve used as the bypass and check valves in
the filter embodiments.
DETAILED DESCRIPTION OF THE DRAWINGS
Referring to Figure 1 a first embodiment of the fil-ter lQ
comprises a generally tubular head casting 11 and a tubular
filter housing 12, the latter having an annular flange piece
14 at one end welded to the housing 1~. The flange 14 has
arcuate slots therein (not shown) for receip-t of mounting
bolts 15 engaging threaded holes in a flange portion 16 of
the head casting 11 to provide a quick-release fastening
arrangement. An o-ring seal 18 between the ~langes 14,
16 provides a fluid seal.
In this embodiment of the invention the head casting 11
includes an inlet port 20 and outlet port 21, generally in
alignment with one another and both disposed substantially
transverse to the longitudinal axis of the tubular housing
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12. The head casting 11 comprises a genarally cylindrical
inner surface 22 extending therethrough, being closed at one
end by inwardJy-dished cover member 24 secured in place at
its periphery by bolts 25 in a ~uick change slotted arrange-
ment similar to that o~ the mounting flange of the filterhousing 12 secured by bolts 15. The distal end of the filter
housing 12 is fitted with a cup-shaped closure member 26,
welded at its peripher~ to the end of the housing 12, the
closure member 26 further including a central closed end
tubular projection 27 which serves as a support memberO
A diverter structure 30 is included in all embodiments of the
invention supporting at one end a tubular filter element 32
and integrally therewith a bypass valve 33, which structures
will be explained in further detail with reference to the
enlarged showings of the different embodiments of the
invention in Figures 2 and 3. In these representations the
same reference numerals are employed for corresponding parts
for ease of understanding.
Referring now to Figure 2 and a second embodiment of the
invention the diverter structure 30 is shown in more detail
as comprising a funnel-shaped structure having a hollow
conical wall portion 35 joined to a generally tubular necked-
down section 36 at the central portion thereof. The conical
wall 35 of the funnel 30 is terminated at its outer end in
a raised edge 38 which is oblique with respect to the
longitudinal axis of the filter. The edge 38 is generally
an oblique section of a cylinder conforming to the inner
surface 22 of the head casting 11 and disposed along a plane
angled with respect to the longitudinal axis of the filter
10. The edge 38 is substantially an annulus in the form of
an elipse having the longer axis lying in the plane of the
paper. A groove 40 is formed at the periphery of the edge
38 of the diverter 30, being bounded in part by the inward
rim 42 which serves to secure an o-ring 44 in the groove 40.
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The rim 42, forming a part of the edge 38 of the diverter
30 is seated against an internal ledge 45, the latter
partially circling the inner surface 22 of the head casting
11 at an oblique angler generally extending from just outside
the outlet port 21 toward a location inside the inlet port
20. The inner surface 22 consists of a larger diameter
portion provi.ding clearance for the diverter 30 and a
reduced diameter seating portion 37, joined by the bevel 39.
The head casting 11 is a die cast aluminum part and re~uires
no further finishing ~or the internal surfaces thereof,
including the seal seating portion 37 and the lead-in bevel
39. The cover member 24 which is in sealed engagem~nt with
the head casting 11 by means of o-ring 48 may engage the
outer portion of the edge 38 or be slightly spaced therefrom,
as shown, to retain the diverter 30 in a seated position.
A projection at 49 on edge 38 and a mating notch in inner
surface 22, assure proper orientation between the diverter
30 and the head casting 11 50 that the tubular portion 36
is concentric with the longitudinal axis of the housing 12.
A pair of supports 50 provide a mounting device for trans-
versely extending p.in 51 which is used for gripping to
assist in removing the diverte~ structure 30 from the head
casting 11. The diverter 30, thus may be readily removed
from or inserted in the head casting 11 by non-rotati.ve
axial movement, the bevel 39 providing an initial compression
of the seal 4~ upon insertion. Engagement of projection 49
in its mating notch and the geometry of the sea~ing parts
~ of the diverter edge 38 and ledge 45 provide the proper
- orientation for the installation.
The diverter 30, which is a molded plastic part, is prefer-
ably mounted in the head casting .11 with the operative axis
of the bypass valve 33 oriented at an angle of 45 from
the axis of ihe outlet port 21. In this location, an
optimum length of opening is p.rovlded for the poppet of the
bypass valve 33 so that it w:Lll not ohstruct the outlet port
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21 or engage the interior wall 22 of the head casting. This
arrangement provides sufficient spacing from the interior
wall 22 so that the mounting boss for the bypass val~e 33
does not disrupt significantly, the smooth flow of fluid
about the extexior of the conical wall 35 of the diverter.
Further, such orientation provides a relatively direct flow
of fluid to the outlet port 21 when the bypass valve is
opened. Still further, such orientation minimizes any jet
stream effect upon the poppet due to impingement of fluid
from the inlet port 20.
The filter element 32 consists of a cartridge type filter
having a perforated tubular wall structure consisting of
concentric inner and outer walls 54, 55 respectively, secured
together at either end b~ means of end caps 56 and sealed at
either end by annular rubber grommets 58. The filter element
32 thus is supported in the housing 12 on the tubular portion
36 of the diverter 30 at one end and at the other end on the
tubular projection 27 of the enclosure 60 in coaxial align~
ment with the tubular housing 12.
In this embodiment of the in~ention end closure 60 comprises
a cup-shaped member ha~ing a central tubular projection 27
with closed inner end 62. The closure member 60 in turn is
releasably secured to the filter housing 12, being welded to
intermediate tubular adapter member 65, the latter having a
radially extending flange 66 secured by the mounting bolts
6~. The adapter member 65 slidably fits with;n a tubular
extension member 69 of the filter housing 12, the extension
member 69 being of slightly greater diameter and welded in
place to the filter housing. A groove 70 is formed in the
adapter member 65 adjacent its inward end to retain o-ring
seal 71 which provides fluid-tight engagement with the I.D.
of the housing extension 69. The arrangement allows relative
sliding movement between the housing e~tension 69 and the
adapter member 65 while maintaining a fluid-tight seal. The
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flange 6~ of the adapter member 65 includes slotted grooves
therein forming a quick-~onnect coupling with the tubular
extension 69 similar to that used at the housing flange 14
proximate to the head casting 11, as well as that for the
cover member 24. Thus it may be seen that the end closure
60 may be rotated a slight amount to be freed from the
loosened mounting bolts 68 and then withdrawn from the end
of the tubular extension 6~9, maintaining fluid-tight engage-
ment until the o-ring 71 separates from the extension 69, a
handle 72 being provided to facilïtate this movement.
conical compression spring 74 is provided between pro]ections
75 on the diverter 30, forming a spring retainer, and the
inner end cap 56 of the filter element 32 thereby urging the
filter element 32 into engagement with the closure member
60, being limited in movement by- the shoulder 76 on the
latter. Thus as the closure member ~0 is withdrawn from the
tubular housing 12 it will be seen that the spring 74 urges
the filter element 32 outwardly such that the outer grommet
58 of the filter element 32 will maintain en~agement with the
shoulder 76 of the enclosure 60. The axial length of the
- tubular extension 69 is selected to be sufficiently long so
that fluid-tight engagement between o-ring 71 and ex-tension
69 is maintained until a position is reached wherein the
inner grommet 58 clears the outer end of the tubular portion
36 of the diverter 30 to establish fluid communication between
the interior of the housing 12 and the interior of the
diverter 30.
In a typical application for such filter embodiment depicted
in Figure 2 housing 12 could be oriented in a vertical
position within a fluid reservoir having a fluid level inter-
mediate the end caps 56 of the filter element 32. In such
arrangement the filter 10 is supported by bolts 68 in an
aperture in the top wall 78 of the reservoir with fluid flow
occuring between the inlet and outlet ports 20, 21. End
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g
closure 60 may be removed as desc~ibed ~or replacement of
filter element 32 and this will introduce air into the upper
part of the reservoir, which if drawn into a pump connected
to the fluid system could cause cavitation and possible
damage. This is prevented by the automatic displacement o~
the filter element 3~ from the ~ubular support 36 of the
diverter 30 under the urging of spring 7~, prior to breaking
the fluid seal effected by o-ring 71. Thus it may be seen
that fluid communication is achieved between the inlet and
outlet ports 20, 21 by way of the central tubular portion 36
of the diverter 30 without the introduction of air into the
fluid system. In this described arrangement the interior
of tubular portion 36 is entirely free of any structure.
~n alternative embodiment however, as fully depicted in
Figure 2, includes a check valve 80 disposed within the
tubular portion 36 of the diverter 30. The valve 80 consists
of a shutoff piston 81 carrying an o-ring seal 82 in a groove
adjacent its inner end. The piston 81 is biased outwardly
toward the distal end of the tubular housing 12 by means of
spring 84 acting between spring retainer 85 and the retaining
clip 86, the latter secured in a groove at the ou-ter end of
the piston 81. The check valve 80 is shown in the closed
position in Figure 2 however under normal operating conditions
such check valve would be in an open position with fluid
communication being provided via axial slots 87 through the
wall of the piston 81, with the o-ring seal 82 being dis-
- posed inwardly within the hollow cone of the diverter
element 30. An actuating device is provided for this purpose
comprising rod 88 threaded at one end and secured to the
piston by means of bolts 89 and engaging at the outer end
the closed wall 62 of the tubular portion 27 of the closure
member 60.
The length of the actuator rod $8 is adjusted so that when
the end closure member 60 is in a fully inward position in
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.
the tubular extension 69 of the filter housing 12, check
valve 80 will be in an open condition such that fluid can
flow through the tubular portion 36 of the diverter 30. As
the end closure 60 is withdrawn from the housing extension
69 shutoff piston 81 will follow the motion of the closure
mem~er through the intermediacy of the actuating rod 88
until the o-ring seal 82 enters the tubular portion 36 and
creates a sealing engagement therewith. Further outward
movement of the shutoff piston 81 is prevented by radially
outwardly projecting flange 90 at the inner e~d thereof.
Fluid flow in all of the embodiments of the invention is
from the center of the filter element 32 to the periphery
thereof and in the embodiments depicted in Figures 1 and 2
is from the inlet port 20 through the diverter cone 35 and
the tubular portion 36 thereof, then through the filter
element 32 to the outlet port 21. In the embodiment of the
invention depicted in Figure 3 however outlet port 21 is
closed by means of a cap 92 secured by bolts 93 and the
second port of the filter 10 is at the distal end of the
filter housing 12. In Figure 3 the filter 10 is mounted to
an adaptor plate 95 in turn mounted to a wall of a fluid
reservoir (not shown) by means of bolts passing through the
apertures 96. In this return line type filter, head casting
11 is disposed outside the wall of the reservoir with the
tubular housing 12 inserted therein into the fluid medium
therein. The end closure or support 98 in this instance is
a cup-shaped member having a similar central tubular extension
27 with a closed inner end wall (not shown) with circumfer-
entially spaced apertures 99 in the side of the cup. Thus
fluid flow is into the port 20 through the di~erter 30 into
the interior of th~ filter element 32 and out the periphery
thereof into the annular space within the tubular housing 12
and through the apertures 99 outwardly of the filter housing
12.
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In an alternative el~bodiment of the invention a check valve
1~0 is secured within the closure member 98. Such check
valve 100 is a unidirectional flow pressure operated poppet
type valve shown more clearly in enlarged form in Figure 6.
The poppet 102 thereon serves to close an aperture formed
in the generally tubular adapter housing 104, the latter
comprisin~ a first annular section 105 threaded into a
tubular support member 106 which in turn is welded in place
within the cup of the end closure member 98. The check
valve 100 comprises a snap-in type poppet assembly which
can be readily interchanged to provide different pressure
operating levels. Alternatel~, the check valve 100 could
be arranged in an opposite disposition by means of a change
of the housing section 105 to check flow of 1uid in the
reverse direction when the ilter 10 is employed with the
distal end of the filter housing 12 as the inlet port.
When the filter is arranged with the distal end of the housing
12 as the inlet port, either with or without a check or
shutoff valve at that location, a cap is placed over the
inlet port 20, and the outlet port 21 opened to act as the
second port for the filter. The apertures 99 in the end
member 98 are closed and a hole is located in the end wall
of the tubular support member 21 so that the inlet is within
the filter element 32. ThuS, fluid f]ow, again, is into
the interior of the fluid element 32 and through its peri-
ph~ry into the annular space inside the filter housing 12,
and then through the outlet port 21. The exterior conical
surface of the divertar element, efficiently dir~cts flow
of fluid to the outlet port 21, and it will be noted that
bypass valve 33 serves, in its usual function, to maintain
a maximum level of fluld pressure differential between
inlet and outlet, regardless of the condition of the filt~r
element 32.
In all the embodiments of the invention a bypass valve 33
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is employed to provide a fluid path between the inlet and
outlet ports of the housing to prevent against a contaminated
condition of the filter element 32 wherein such blocked
filter might disrupt fluid flow or create too high a pressure
drop. The bypass valve 33 is similar to the shutoff valve
102 depicted in Figure 3 comprising a snap-in type replace-
able poppet valve assembly adapted for quick interchange
upon removal of the diverter 30 from the head casting 11.
The poppet valve 33 is depicted in cross-section in Figure 6
and is adapted to be mounted în an aperture in a flat surface
formed as a generally transversely extending boss 108 dis-
posed in the conical side wall 35 o~ the fluid diverter 30.
The flat surface oE the boss 10~ lies in a plane generally
parallel with the longitudinal axis of the filter and
includes circumferentially spaced notches 109 about the
central opening therein forming a part of a quick-connect
arrangement and adapted to mount the bypass valve 33 within
the hollow cone of the diverter 30 in a generally trans-
verse position.
Referring now to Figure 6 it is seen that the valve 33
comprises a circular poppet 110 adap-ted to close upon a
raised annular seat 112 in a generally circular poppet
mount 114. The poppet is formed of nylon and the pGppet
mount 114 is preferably formed of glass filled nylon and
the latter includ~s a central hub portion 115 supported
by several radially extending legs 116, having spaces there-
between forming apertures for fluid flow through -the mount
114. The hub 115 has a central bore for supporting a pin
120 therein, the latter having a head at one end for retain- -
ing the poppet 110 and a clip 121 at the other end securing
a spring retainer 122 for guiding compression spring 12~.
The retaining clip 121 ma~ be placed in different ones of
cross holes 126 for varying the bias of the spring 12~.
The outer periphery of the poppet mount 114 is formed as a
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plurality of upstanding legs 1~8 each having a catch 129
thereon which is adapted to pass through a notch 109 in the
boss 108 on the diverter 30 until engagement occurs between
a peripheral ridge 130 on the poppet support 114 and the
lower surface of the boss 108. Partial rotation of the
poppet assembly then will cause the catches 129 on the
upstanding legs 128 to ride up on slight inclines on the
outer face of the boss 108 until a slight depression is
reached to secure the assembly in fluid-tight engagement
within the boss 108.
Referring now to Figures 4 and 5 there is shown the indicator
elem~nt 140 of the invention which provides a visual indica-
tion of the fluid pressure differential within the filter
housing 12 and thus an indication of the condition of the
filter element 32. Figure 4 is a view toward the inlet port
20 of that embodiment of the invention shown in Figure 1,
the port 20 being a bore in the boss 142 protruding from
the head casting 11. The position of the edge 38 of the
diverter 30 is depicted in dashed lines in Figure 4/ the
o-ring seal on such edge 38 dividing the interior of the
head casting 11 into two portions isolated from one another
and which communicate respectively with the inlet and outlet
ports of the filter 10. Lateral bosses 144, 146 protrude
from the head casting 11 each having a port therein
communicating with the interior of the head casting 11 on
opposite sides of the o-ring seal on the edge 38 of the
diverter 30. Thus bosses 146 have bores therein in
~` communication with the inlet port 20 while boss 144 has a
bore therein in communication with outlet port 21.
The indicator 140 comprises a housing formed of identical
end structures 148 securing a glass sleeve 149 therebetween
by means of bolts 1500 The slee~e 149 and recesses in the
end caps 148 form a central c~lindrical chamber in which is
disposed a piston structure consisting of back-to-back upper
~5~B~
and lower cup-shaped members 152, 154 respectively secured
by bolt 155.
A pair of diaphragms are secured at one end between the
sleeve 149 and the end members 148 and at the other end at
opposite ends of an indicator sleeve 160 secured between
shoulders of the upper and lower cup-shaped piston members
152, 154. The diaphragms 158, 159 are annular rolling
diaphragms having a fold intermediate their respective ends
and are positioned such that there is a short axial space
between the adjacent folds indicated generally at the arrow
162. It will be seen that as the piston assembly 152, 154
moves upwardly and downwardly within the cylindrical chamber,
the viewing space 162 will maintain appro~imately the same
spacing between folds but will move upwardly and downwardly
with the piston to expose different axial segments of the
indicator sleeve 160. As seen in Figure 4 the indicator
sleeve 160 is colored with dif~erent bands to provide a
visual indication of the di~ferent positions of the piston
assembly therein.
~,
The indicator housing 140 is mounted to the head casting 11
at the bosses 146, 144 by means of bolts 163, with sealing
being effected by o-rings 165. Bores in the ports 146,
144 communicate with the indicator housing bores 166, 164
which in turn communicate respectively with the chambers
~ormed above the upper diaphragm 158 and below the lower
diaphragm 159. Thus, fluid pressure on ei~her side of the
diverter edge 38 is applied to the piston assembly 152,
. 154 to effect a differential force upon the piston assembly
and a positioning of same in a manner well-understood in
the art. A light compression spring 180 is mounted between
a boss in the lower housing section 148 and the inside well
of the lower piston portion 154, thereby continuously urging
the piston assembly in an upward direction as viewed in
. Figure 5. A second spring 182 having a higher spring rate
189~
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than that of spring 180 i5 coaxially mounted therewith but
terminates at the last coil 183 thereof out of contact with
the lower piston portion 154 such that the spring 182 is not
engaged until the piston assembly has moved to a position
where indications are desired of the fluid pressure differ-
ential within the filter 10 housing. In this manner a
different spring rate may be provided for fluid pressure
differential indications while the light spring bias provided
by spring 180 serves to retain the piston assembly fully in
one position in the absence of any fluid pressure differen-
tial acting against the diaphragms 158, 159. A magnet 185
is further secured in the inner well of the upper piston
element 152 and is adapted to create a magnetic field outside
of the housing 148 for actuation of a reed switch or the
like (not shown) to provide a remote indication of the
piston assembly position and thus of the contaminated
condition of the filter element 32, or even the lack of
filter element in the filter.
As noted in Figure 4 the indicator sleeve 1~0 is divided
into several axially spaced segments of different colors
ranging from white through green and yellow to red, wherein
white gives an indication of absence of filter element,
green the proper operating pressure differenkial, and yellow
and red indicating higher pressure differentials, demon-
strating a relatively clogged condition of the filterelement 32, and indicating the need for replacement thereof.
