CA1151898A - Fluid filter and indicator - Google Patents

Abstract

ABSTRACT

A versatile filter structure adaptable for use in differently ported configurations includes accommodation for variations of bypass and shutoff valving and for filter element replace-ment from either end or centrally of the structure. A head casting is secured to a tubular housing and either may be the mounting device for the filter. A funnel shaped diverter having an oblique edge is removably mounted in the head casting and provides separation between inlet and outlet portions of the filter structure by means of an eliptical o-ring seal at the edge which engages the interior of the head casting. The diverter provides a smooth transition for fluid flow to the interior of the filter, supports one end of the filter element in the tubular housing, optionally houses a shutoff valve operative automatically upon filter element removal, and further houses a bypass valve for safe-guarding against filter element blockage. The remote end of the housing which also supports the filter element consists in the different configurations of a welded-closed or removable end assembly, with or without a port and shutoff valving. An indicator mounted on the head casting is in fluid communication with opposite sides of the o-ring seal to monitor inlet and outlet pressure differentials. Dual diaphragms actuate and isolate a sensing piston in the indicator and a dual spring arrangement biases the piston for normal operation and to provide an indication of lack of filter element in the housing.

Description

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 ' ' . ' ' B~8 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.

Figure 1 is a longitudinal sectional view of a preferred embodiment of the filter in an in-l~ne ported arrangement.

-. . :

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 :

3l8~3 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.

: .

~51898 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 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 :

~ .~

~51~

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 ~S~89~
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 :

~5~8~8 .

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.

~51~9B

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 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 5~8 -- 13 ~

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~

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.

Claims (6)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A differential pressure indicator, comprising a chamber, a piston reciprocable therein, means sealing said piston in said chamber for response to fluid pressure, means communicating fluid pressure to opposite sides of said piston for movement of said piston as a function of fluid pressure difference, first spring means in the path. of movement of said piston to be contacted by said piston and to variably resist move-ment thereof, means for providing a visual display of the position of said piston, and second spring means in engagement with said piston for biasing said piston to one end of said chamber, out of contact with said first spring means, to provide an indication of lack of fluid pressure difference.

2. The indicator set forth in claim 1 wherein said spring means are compression springs concentrically disposed in said chamber, only one of said springs being in engage-ment with said piston when the latter is at one end of said chamber.

3. The indicator set forth in claim 2 wherein said chamber is formed in part of a tube and the central portion of said tube is transparent for viewing the position of the piston therein.

4. The indicator set forth in claim 3 wherein said seal-ing means comprise first and second diaphragms in sealing engagement with said chamber and in sealing engagement with said piston therebetween.

5. The indicator set forth in claim 4 wherein said diaphragms are folded diaphragms adapted to roll with move-ment of said piston to expose only a small portion of said piston at each position of movement thereof, said display means comprising indicator bands which are uncovered by said diaphragms, one of said bands providing an indication of lack of fluid pressure difference.

6. The indicator set forth in claim 5 wherein said piston comprises magnetic means for actuation of a magnetic ally responsive device external of said chamber to provide a further indication of the position of said piston.