Filter arrangement and methods

A filter arrangement includes a filter cartridge having a first filter element and a second filter element. The first filter element includes a first tubular section of filter media extending between first and second end caps and defining a first open filter interior. The second filter element includes a second tubular section of filter media operably oriented in the first open filter interior. The second tubular section of filter media extends between third and fourth end caps and defines a second open filter interior. The first end cap defines an inner container and an outer container circumscribing the inner container. The outer container is secured to the first tubular section of filter media. The inner container has an end wall axially spaced from the outer container. The third end cap has a media end secured to the second tubular section of filter media and a tubular wall axially extending from the media end. The tubular wall is circumscribed by the inner container of the first end cap. The filter arrangement further includes a housing for the cartridge, and can be either a spin-on or a bowl-cartridge filter. The filter arrangement is usable in a hydraulic system including a sump; an implement valve; a pump; and a filter head in fluid communication with the sump, implement valve, pump, and filter arrangement.

This application is being filed on Jul. 8, 2009 as a National Stage of PCT International Application No. PCT/US2008/050463, in the name of Donaldson Company, Inc., a U.S. national corporation, applicant for the designation of all countries except the US, and Gary H. Gift and Jeffrey J. Theisen, both citizens of the U.S., applicants for the designation of the US only, and claims priority to U.S. Provisional Application Ser. No. 60/884,093, filed Jan. 9, 2007. These applications are incorporated herein by reference.

TECHNICAL FIELD

This disclosure relates to filter assemblies, filter elements, methods of filtering, and methods of servicing. In example implementations, this disclosure relates to filtering technology useful for purifying hydraulic systems used in, for example, heavy equipment such as tractors.

BACKGROUND

Filter devices are used in many types of applications. In one application, filter devices are used to filter hydraulic fluid, for example, hydraulic oil in hydraulic systems. In many cases, the hydraulic systems must meet high demands to fulfill intended functions while not wearing over the operating times. Over a period of use, the filter devices will become clogged with debris and particulate matter. The filter devices, therefore, must be either cleaned or replaced. In many typical filters, the filters are designed to be removed, disposed of, and replaced with new filters. Improvements in filter devices are continually being sought.

SUMMARY OF THE DISCLOSURE

A filter arrangement includes a filter cartridge having a first filter element and a second filter element. The first filter element includes a first tubular section of filter media extending between first and second end caps and defining a first open filter interior. The second filter element includes a second tubular section of filter media operably-oriented in the first open filter interior. The second tubular section of filter media extends between third and fourth end caps and defines a second open filter interior. The first end cap defines an inner container and an outer container circumscribing the inner container. The outer container is secured to the first tubular section of filter media. The inner container has an end wall axially spaced from the outer container. The third end cap has a media end secured to the second tubular section of filter media and a tubular wall axially extending from the media end. The tubular wall is circumscribed by the inner container of the first end cap.

In preferred embodiments, the filter arrangement further includes a housing having a surrounding wall defining an interior volume. The housing includes connection structure to permit selective attachment to a filter head. The filter cartridge is operably oriented within the interior volume of the housing. In one embodiment, the filter cartridge is removable and replaceable within the housing, to be a bowl-cartridge filter. In another embodiment, the filter cartridge is permanently secured within the housing, to be a spin-on filter.

In another aspect, a hydraulic system is provided. The hydraulic system includes a sump; an implement valve; a pump; a filter head in fluid communication with the sump, implement valve, and pump; and a filter arrangement operably and removably secured to the filter head. The filter head includes a sump inlet arrangement downstream of the sump, an implement valve inlet arrangement downstream of the implement valve, and a pump outlet arrangement upstream of the pump. The filter arrangement includes a filter housing having an interior volume and a filter cartridge operably oriented in the interior volume. The filter cartridge can be the type as characterized above. The sump inlet arrangement is upstream of and in fluid communication with an upstream side of the first filter element. The upstream side of the first filter element is an outer side of the first tubular section of filter media. The implement valve inlet arrangement is upstream of and in fluid communication with the upstream side of the second filter element. The pump outlet arrangement is downstream of and in fluid communication with the downstream side of the first filter element and a downstream side of the second filter element. The downstream side of the second filter element is an outer side of the second tubular section of filter media.

In another aspect, a method of servicing a filter arrangement includes removing a filter housing from a filter head. The filter housing contains a filter cartridge; and providing a new, replacement filter cartridge. The new, replacement filter cartridge includes a first filter element and a second filter element. The first filter element and the second filter element can be the type as characterized above.

DETAILED DESCRIPTION

InFIG. 1, a schematic of a hydraulic system is shown generally at20. The hydraulic system20includes a sump22, a pump24, and an implement valve26. In fluid communication with the sump22, pump24, and implement valve26is a filter arrangement30. The filter arrangement30includes a first filter element32and a second filter element34. In the hydraulic system20, the first filter element32functions as a suction filter33, while the second filter element34functions as a return filter35. In this embodiment, the first filter element32has an outer bypass valve arrangement38, while the second filter element34has an inner bypass valve arrangement40. There is a strainer42in fluid communication with the flow paths opened by the first bypass valve arrangement38and second bypass valve arrangement40.

In operation, hydraulic fluid is drawn through the suction filter33from the sump22. Between the sump22and the filter33, the fluid flows at a very low (if any) operating pressure, such as about 0 psi. It then flows to an outflow path44to the pump24. Between the pump24and the downstream side of the filter33, the fluid is flowing at an operating pressure of about −1 psi. The pump24pumps the hydraulic fluid to be used by downstream hydraulics. After the fluid has been used by the downstream hydraulics, it flows back through the implement valve26. In typical systems, the fluid from the implement valve26flows at an operating pressure of about 5 psi, through the return filter35, and then into the outflow path44. At the outflow path44, it joins fluid that has flown through the suction filter33. If the suction filter33becomes occluded or in the case of a cold-start, the bypass valve arrangement38opens and allows hydraulic fluid to flow around or bypass the suction filter33. The cracking pressure of the bypass valve arrangement38will be selected based on the system, and can be about 0.5 bar (7.5 psi). The fluid then flows through fluid bypass path46. From there, it flows through strainer42and into the outflow path44. Similarly, if the return filter35becomes occluded, the bypass valve arrangement40opens and allows the fluid to flow around or bypass the return filter and flow into bypass path48. The cracking pressure of the bypass valve arrangement40will be selected based on the system, and can be about 2 bar (29 psi). From there, the fluid flows through strainer42and into the outflow path44.

FIG. 2depicts an alternate embodiment of the hydraulic system20, depicted at20′. The hydraulic system20′ depicted inFIG. 2is the same as system20ofFIG. 1, except that the strainer42has been omitted. In some applications, the strainer42is not necessary. The strainer42will typically comprise a wide mesh and will collect only large particles. The bypass valves38,40will open during a cold-start condition when the oil has a high viscosity; however, there could be a significant pressure drop across the strainer42at these cold temperatures. This high pressure drop could cause cavitation of the pump24and poor hydraulic performance. Therefore, the added cost of the strainer42and potential limitations during a cold start-up may provide reasons to not use the strainer42. It should be understood that the filter arrangement30described herein can alternatively include or not include the strainer42.

Attention is directed toFIGS. 3 and 4. The filter arrangement30shown in the hydraulic system20,20′ is depicted. InFIG. 3, the filter arrangement30includes a housing50including a surrounding wall52defining an interior volume54. The housing50includes connection structure56, depicted as threads58along the inner surface of the wall52at an open mouth60. Opposite to the open mouth60is a closed end62. While the housing50can be made from a variety of materials, in one embodiment, the housing50is made from non-metal, such as plastic.

Operably oriented within the housing50is a filter cartridge64. In one embodiment, the filter cartridge64is removable and replaceable from the housing50, such that the filter arrangement30is a bowl-cartridge filter. In the embodiment depicted inFIG. 4, the filter cartridge64is permanently mounted within the housing50, such that the filter arrangement30is a spin-on filter. A spin-on filter is one in which, when the filter arrangement30is serviced, the entire housing50and filter cartridge64are replaced with a new housing50containing filter cartridge64. In a bowl-cartridge filter, the filter cartridge64is removed from the housing50and replaced with a new filter cartridge64, and the housing50is not replaced.

The filter cartridge64includes the first filter element32, functioning as suction filter33and second filter element34, functioning as return filter35.FIGS. 5 and 6depict the first filter element32, whileFIGS. 7 and 8depict the second filter element34.

The first filter element32includes a first tubular section of filter media66. The media66can be a variety of types of media, and typically will be pleated media made from synthetic material. The media66may also be cellulose, for example. The first tubular section of filter media66extends between a first end cap68and a second end cap70. As can be seen inFIG. 6, the first tubular section of filter media66defines a first open filter interior72. Lining the filter media66and extending between the first end cap68and second end cap70and defining the first open filter interior72is an inner liner74.

The second end cap70defines an opening76, and as such, is an open end cap. The opening76allows fluid access to the first open filter interior72. The second end cap70includes an upstanding ring78and is supported by a series of spaced vanes80. The second end cap70also includes a plurality of hooked flanges82extending radially outwardly therefrom and in a direction opposite of the upstanding ring78. In the spin-on embodiment, the flanges82catch a protrusion84(seeFIG. 4) extending from an interior surface of the housing surrounding wall52.

FIG. 17illustrates a cross-sectional view of a portion of the first filter element32, but depicts an alternative arrangement of the second end cap, shown at70′. The second end cap70′ includes upstanding ring78supported by spaced vanes80. The second end cap70′ also includes hooked flanges82′. While in the embodiment ofFIG. 6, the flanges82are J-shaped, in the embodiment ofFIG. 17, the flanges82′ each defines a catch83and defines an open volume x between a stem85of the flange82′ and a remaining portion of the second end cap70′. The volume x allows for space so that the stem85can deflect radially inwardly while the filter cartridge64is being installed in the housing50. The catch83will engage or catch protrusion84(FIG. 4) extending from an interior surface of the housing surrounding wall52.

FIG. 18shows another embodiment of the second end cap70″. The embodiment of the second end cap70″ is the same as the embodiment of70′ ofFIG. 17, except that the catch83″ defines a sloped surface87. The sloped surface87is an angled surface that angles in a direction from a remaining portion of the first filter element32downwardly. This feature allows the filter cartridge64to be selectively removable and replaceable from the filter housing50. Thus,FIG. 18illustrates an embodiment of filter cartridge64that would operate as a bowl-cartridge filter assembly. The sloping surface87allows the filter element32to be installed within the housing50, such that the catch83″ engages protrusion84ofFIG. 4. The slope87along with the gap or space x allows the stem85to deflect inwardly and the catch83″ to disengage from the protrusion84, which allows the filter arrangement30to be removed from the housing50. By comparingFIG. 17andFIG. 18, it should be appreciated thatFIG. 17would generally be a spin-on embodiment, whileFIG. 18would be a bowl-cartridge filter embodiment.FIG. 19illustrates the filter arrangement30, including the first filter element32of the embodiment ofFIG. 18, with the second end cap70″. InFIG. 19, the filter cartridge64is shown how it can be selectively inserted and removed from the housing50through the open mouth60.

Returning again toFIG. 6, the second end cap70further includes a groove86along an interior portion of the upstanding ring78. The groove86is a seat for a seal member88. The seal member88forms a releasable seal90(seeFIG. 14) with a filter head92.

In reference now toFIG. 6, the first end cap68defines an inner container94and an outer container96. The outer container96circumscribes or surrounds the inner container94. The outer container96includes an outer rim98, and perpendicular to the outer rim98, a base100. The base100is secured to the first tubular section of filter media66at an end102. The base100extends between the outer rim98and wall104of the inner container94. Perpendicular to the wall104and generally parallel to the base100is an end wall106. Together, the end wall106and wall104define an inner container volume108. The inner container volume108also defines the bypass flow path46. As can be seen inFIG. 6, the end wall106is axially spaced from base100and outer container94.

The inner container94operably holds the outer bypass valve arrangement38therein. InFIG. 6, it can be seen how the outer bypass valve arrangement38includes a valve head110mounted on a valve seat112. The valve seat112extends perpendicularly from the end wall106into the inner container volume108. A spring member114functions to bias the valve head114in a closed position against the valve seat112. In a cold-start condition or when the filter media66is occluded, fluid pressure will build against an upstream side116of the valve head110, and the force will be greater than the force exerted by the spring member114. Eventually, the force against the upstream side116of the valve head110will be greater than the spring member114and cause the valve head110to move away from the valve seat112. This will open a gap between the valve seat112and the valve head110, permitting fluid to flow into the inner container volume108, which is also the bypass flow path46. This is also in fluid communication with the first open filter interior72(which, in the embodiment depicted, is a downstream side118of the filter media66—the upstream side120of the media66is the outer, exterior portion of the filter media66.)

Attention is next directed toFIGS. 7 and 8. The second filter element34is depicted. The second filter element34includes a second tubular section of filter media122having an upstream side124and a downstream side126. The second tubular section of filter media122defines a second open filter interior128which is adjacent and next to the upstream side124. The filter media122can be various types of media, and in the embodiment shown, is pleated media. The media122can be made from various materials including synthetic or cellulose media. The second tubular section of filter media122extends between a third end cap130and a fourth end cap132. In the embodiment illustrated, the second filter element34further includes an outer liner123extending between the third end cap130and the fourth end cap132. The outer liner123can be made from perforated metal.

The fourth end cap132includes an outer rim134. Projecting from the outer rim134are a plurality of hooked flanges136. In the embodiment shown, there are four, evenly spaced, hooked flanges136. As can be seen in the embodiment ofFIG. 4, the hooked flanges136engage by hooking onto an interior rim138of the second end cap70of the first filter element32.

The fourth end cap132further includes an end wall140generally perpendicular to the outer rim134. The end wall140and outer rim134together define a holding tray for securing an end of the media122.

The fourth end cap132further includes a centrally extending tubular wall142. The tubular wall142defines an opening144, which is in open, fluid communication with the second open filter interior128. The tubular wall142defines a groove146along the outer radial surface for holding a seal member148. The seal member148forms a seal150(seeFIG. 14) with the filter head92, when the filter arrangement30is operably connected to the filter head92.

The third end cap130has an outer wall152and first and second opposite ends154,156. The first end154also corresponds to a media end158and is secured to the second tubular section of media122. The outer wall152is a tubular wall and extends from the media end154terminating at the second end156. The end156is remote from the filter media122. When the second filter element34is operably part of the filter assembly30, the tubular wall152of the third end cap130is oriented within the volume108of the inner container94and is circumscribed by the inner container94.

In the hydraulic system ofFIG. 1which uses strainer42, the strainer42is part of the third end cap130. Attention is directed toFIGS. 8-11, which shows the third end cap130. The third end cap130includes strainer42depicted, in this embodiment, as a plurality of mesh screens160supported and held by a frame162. The frame162is depicted as a plurality of spaced support members extending longitudinally along the end cap130. In typical embodiments, the end cap130including the frame162will be made from a non-metal material, such as plastic. The screens160will be an open mesh that prevents large debris from passing into the outflow channel44and otherwise does not impede flow. The mesh size for the screens can vary, based on the system, and in typical systems can be about 250 micron or 50 mesh (50 wires/inch).

As can be seen inFIG. 4, when the second filter element34and the first filter element32are operably assembled together, the tubular wall152of the third end cap130is oriented against the end wall106of the inner container94. As can be seen, the tubular wall152includes the strainer42extending between the media end158of the third end cap130and the end wall106of the inner container94.

Attention is again directed toFIG. 8. The inner bypass valve arrangement40is secured to the third end cap130and is within the open filter interior128of the second tubular section of media122. The inner bypass valve arrangement40is constructed similarly to the outer bypass valve arrangement38. The inner bypass valve arrangement40includes a valve head164biased against a valve seat166by a spring member168. The valve seat166is defined by the third end cap130. An upstream side of the valve head is shown at170and is in fluid communication with the upstream side124of the second tubular section of media122. In the case of a cold-start or when the filter media122is occluded, the pressure on the upstream side170of the valve head164will overcome the pressure caused by the force of the spring168. This will open a gap between the valve head164and valve seat166, which will permit fluid to flow into volume172. Volume172is the inner volume defined by the tubular wall152of the third end cap130. From there, the fluid flows through the screen160of the strainer42and then to the outflow path44.

FIGS. 12-16depict the overall filter assembly180, which includes filter head92operably connected to the filter arrangement30. The filter head92is in fluid communication with the hydraulic system20. InFIG. 12, an implement valve inlet port182is viewable. The implement valve inlet port182is in fluid communication with the implement valve26.

FIG. 13is also a perspective view of a filter assembly180. In the view inFIG. 13, the sump inlet port184can be seen, as well as the pump outlet port186. The sump inlet port184is downstream of and in fluid communication with the sump22. The pump outlet port186is upstream of and in fluid communication with the pump24.

FIGS. 14-16depict cross-sectional views of the filter assembly180and show operative flow paths through the assembly180.FIG. 14shows fluid flowing from the sump22(FIGS. 1 and 2) through the sump inlet port184, into the volume188defined between the upstream side120of the first filter element32and an inner section of the housing wall52. From there, in normal conditions, the fluid will flow through the first tubular section of filter media66, into the first open filter interior72, into the outflow path44, and back into the filter head92in a space between the first filter element32and second filter element34.

Also viewable inFIGS. 14-16is a seal192between the filter head92and the housing50. The seal192is created by seal member190circumscribing the open mouth60of the housing50.

FIG. 15shows the outflow path44and the filtered fluid flowing back into the filter head92and through the pump outlet port186. The filtered fluid then travels to the pump24. InFIG. 15, the fluid is also shown entering the filter head92from the implement valve26(FIGS. 1 and 2) through the implement valve inlet port182. From there, the fluid flows through the opening144in the tubular wall142of the second filter element34. From there, it enters into the second open filter interior128. During normal conditions, the fluid then flows through the second tubular section of filter media122and to the outflow path44, where it meets up with fluid that has flown through the first tubular section of filter media66, in which it then flows into the filter head92and out through the pump outlet port186.

FIG. 16illustrates flow paths during conditions that open the outer bypass valve arrangement38and inner bypass valve arrangement40. WhileFIG. 16illustrates both bypass valve arrangements38and40in an open condition, it should be understood that during some situations, only one or the other of the bypass valve arrangements38,40may be open. When the outer bypass valve arrangement38is open, the fluid flows into the inner container volume108, then flows through the screen160of the strainer42, and then into the outflow path44. When the inner bypass valve arrangement40is opened, the fluid flows from the second open filter interior128, into the inner container volume108, through the screen160, and into the outflow path44.

After a period of operation, the filter arrangement30will be in need of servicing. To service the filter arrangement30, the filter housing50is removed from the filter head92. The filter housing50contains the filter cartridge64. If the filter arrangement30is a spin-on filter, then the entire housing50plus filter cartridge64is disposed of and replaced with a new filter housing50having a new filter cartridge64. If, alternatively, the filter arrangement30is a bowl-cartridge filter, then the filter cartridge64is removed from the housing50, and a new filter cartridge64is replaced within the same, old housing50. The new filter arrangement30is then operably mounted onto the filter head92.

Attention is next directed to the filter arrangement230depicted inFIGS. 20-23. The filter arrangement230is similar to the filter arrangement30ofFIG. 3, but with some distinctions. For example, in the filter arrangement230, there is no outer bypass valve analogous to outer bypass valve38. This is because the media266used in the first filter element232has a greater porosity level and is less restrictive than the analogous media66for the analogous first filter element32of the embodiment ofFIGS. 3 and 4. Preferably, the media266is an open porous screen, which means the likelihood of undue restriction across the media266not at a level to cause the need for a bypass valve. Because there is no outer bypass valve, the first endcap268, analogous to the first endcap68, is closed and is bypass valve-free; that is, there is no opening or valve seat.

Other differences between the filter arrangement230ofFIG. 20and the filter arrangement30ofFIG. 3includes the end shape of the housing250has a rounded dome across the bottom251rather than a hexagonal shape as shown for the housing50ofFIG. 3. The rounded dome shape of the bottom251is to provide increased strength to the housing250. In addition, at the bottom251, there is a square-shaped socket253(FIG. 23)to allowthe user to both tighten and loosen the filter arrangement230from the filter head292.

Another difference between the embodiment of the filter arrangement230and the filter arrangement30is the general geometry of the hooked flanges336extending from the second filter element234. The hooked flanges336functionally do the same thing as hooked flanges136, in that they engage by hooking onto an interior rim338(FIG. 22) of the second endcap270of the first filter element232. In the embodiment ofFIG. 27, the hooked flanges336have a greater arched leg337than the embodiment shown inFIG. 7at136.

A further difference between the embodiment of filter arrangement30and filter arrangement230is the difference between the outer rim98of the first endcap68and the outer rim298of the first endcap268. The outer rim298has a lip299(FIG. 26) that deflects radially outwardly and engages or catches spaced ribs301(FIG. 22) on the housing250. This engagement between the lip299and the spaced ribs301provides stability and prevents rattling of the filter arrangement230within the housing250.

A summary of the features of the embodiment of the filter arrangement230are now described. As mentioned above, in general, the functions and features of the filter arrangement230are analogous to the functions and features of the filter arrangement30, except for the differences mentioned above. The filter arrangement230includes housing250having surrounding wall252defining an interior volume254. The housing250includes connection structure256, depicted as threads258along the inner surface of the wall252at the open mouth260. Opposite to the open mouth260is a closed end262which is also the bottom of the housing251. While the housing250can be made from a variety of materials, in one embodiment, the housing250is made from non-metal, such as plastic.

Operably oriented within the housing250is a filter cartridge264. In one embodiment, the filter cartridge264is removable and replaceable from the housing250, such that the filter arrangement230is a bowl-cartridge filter. In the embodiment depicted inFIG. 22, the filter cartridge264is permanently mounted in the housing250, such that the filter arrangement230is a spin-on filter. Definitions of a spin-on filter and a bowl-cartridge filter are provided above, in connection with the description of the filter arrangement30.

The filter cartridge264includes the first filter element232functioning as suction filter233and second filter element234, functioning as return filter235.FIGS. 24-26depict the first filter element232, whileFIGS. 27-29depict the second filter element234.

The first filter element232includes a first tubular section of filter media266. The media266can be a variety of types of media, and in this embodiment will be an open, porous screen. As mentioned above, this is one of the differences between the filter arrangement230and the filter arrangement30. The first tubular section of filter media266extends between first endcap268and second endcap270. The first tubular section of filter media266defines a first open filter interior272. Lining the filter media266and extending between the first endcap268and second endcap270and defining the first open filter interior272is an inner liner274.

The second endcap270defines an opening276, and as such, is an open endcap270. The opening276allows fluid access to the first open filter interior272. The second endcap270includes an upstanding ring278and is supported by a series of spaced vanes280. The second endcap also includes a plurality of hooked flanges282extending radially outwardly therefrom and in a direction opposite of the upstanding ring278. In the spin-on embodiment, the flanges282catch a protrusion284extending from an interior surface of the housing surrounding wall252.

As with the embodiment of the filter arrangement30, the filter arrangement230can include variations, such as those shown inFIGS. 17 and 18.FIG. 18would allow the filter arrangement230to be a bowl-cartridge filter embodiment.

The second endcap270further includes a groove286along an interior portion of the upstanding ring278. The groove286is a seat for a seal member288. The seal member288forms a releasable seal290with a filter head292.

The first endcap268defines an inner container294and an outer container296. The outer container296circumscribes or surrounds the inner container294. The outer container296includes outer rim298, and perpendicular to the outer rim298, a base300. The base300is secured to the first tubular section of filter media266at an end302. The base300extends between the outer rim298and the wall304of the inner container294. Generally parallel to the base300is an end wall306. Together, the end wall306and the wall304define an inner container volume308. The end wall306is axially spaced from the base300and outer container296.

As described above, in this embodiment, the inner container294is solid, closed, and bypass valve-free. Because the media266is an open-porous screen, the risk of having a high restriction across the media266is less of a concern.

The second filter element234includes a second tubular section of filter media322having an upstream side324and an downstream326. The second tubular section of filter media322defines a second open filter interior328which is adjacent and next to the upstream side324. The filter media322can be various types of media, and in the embodiment shown, is pleated media. The media322can be made from various materials including synthetic or cellulose media. The second tubular section of filter media322extends between a third endcap330and a fourth endcap332. In the embodiment illustrated, the second filter element234further includes an outer liner323extending between the third endcap330and fourth endcap332. The outer liner323can be made from perforated metal.

The fourth endcap332includes outer rim334. Projecting from the outer rim334are the plurality of hooked flanges336, described above. In this embodiment, there are three evenly-spaced hooked flanges336. The hooked flanges336engage by hooking onto an interior rim338of the second endcap270of the first filter element232. The fourth endcap332further includes an end wall340generally perpendicular to the outer rim334. The end wall340and outer rim334together define a holding tray335for securing an end of the media322. The fourth endcap332further includes a centrally-extending tubular wall342. The tubular wall342defines an opening344, which is in open fluid communication with the second open filter interior328. The tubular wall342defines a groove346along the outer radial surface for holding a seal member348. The seal member348forms a seal350(FIG. 31) with the filter head292, when the filter arrangement230is operably-connected to the filter head292.

The third endcap330has an outer wall352and first and second opposite ends354,356. The first end354also corresponds to a media358end and is secured to the second tubular section of media322. The outer wall352is a tubular wall and extends from the media end354terminating at the second end356. The end356is remote from the filter media322. When the second filter element234is operably part of the filter assembly230, the tubular wall352of the third endcap330is oriented within the volume308(FIG. 26) of the inner container294and is circumscribed by the inner container294.

In the hydraulic system ofFIG. 1which uses strainer42, the strainer342is part of the third endcap330. The third endcap330includes strainer342depicted, in this embodiment, as a plurality of mesh screens360supported and held by a frame362. The frame362is depicted as a plurality of spaced support members extending longitudinally from the endcap330. In typical embodiments, the endcap330including the frame362will be made from a non-metal material, such as plastic. The screens360will be an open mesh that prevents large debris from passing into the outflow channel244and otherwise does not impede flow. The mesh size for the screens can vary, based on the system, and in typical systems, can be about 250 micron or 50 mesh (50 wires/inch).

When the second filter element234and the first element232are operably-assembled together, the tubular wall352of the third endcap330is oriented against the end wall306of the inner container294. As can be seen inFIG. 22, the tubular wall352includes the strainer242extending between the media end358of the third endcap330and the end wall306of the inner container294.

The inner bypass valve arrangement240is secured to the third endcap330and is held within the open filter interior328of the second tubular section of media322. The inner bypass valve arrangement240is constructed similarly to the inner bypass valve arrangement40. The inner bypass valve arrangement240includes a valve head364biased against a valve seat366by a spring member368. The valve seat366is defined by the third endcap330. An upstream side of the valve head is shown at370and is in fluid communication with the upstream side324of the second tubular section of media322. In the case of a cold start or when the filter media322is occluded, the pressure on the upstream side370of the valve head364will overcome the pressure caused by the force of the spring368. This will open a gap between the valve head364and the valve seat366, which will permit fluid to flow into the volume372. The volume372is the inner volume defined by the tubular wall352of the third endcap330. From there, the fluid flows through the screen360of the strainer242and then to the outflow path244.

The overall filter assembly380includes filter head292operably-connected to the filter arrangement230. The filter head292is in fluid communication with the hydraulic system20. InFIG. 31, an implement valve inlet port382is viewable. The implement valve inlet port382is in fluid communication with the implement valve26.

InFIG. 32, the sump inlet port384can be seen. The sump inlet port384is downstream of and in fluid communication with the sump22. The pump outlet port386,FIG. 31, is upstream of and in fluid communication with the pump84.

FIGS. 31 and 32depict cross-sectional views of the filter assembly380and show operative flow paths through the assembly380.FIG. 32shows fluid flowing from the sump22through the sump inlet port384, into the volume388defined between the upstream side320of the first filter element232and an inner section of the housing wall252. From there, the fluid will flow through the first tubular section of filter media266, into the first open filter interior272, into the outlet flow path244, and back into the filter head292in a space between the first filter element232and the second filter element234.

Also viewable, inFIGS. 31 and 32is a seal392between the filter head292and the housing250. The seal392is created by seal member390(FIG. 22) circumscribing the open mouth260of the housing250.

FIG. 31shows the outflow path244and the filtered fluid flowing back into the filter head292and through the pump outlet port386. The filtered fluid then travels to the pump24. InFIG. 31, the fluid is also shown entering the filter head292from the implement valve26through the implement valve inlet port382. From there, the fluid flows through the opening344in the tubular wall342of the second filter element234. From there, it enters into the second open filter interior328. During normal conditions, the fluid then flows through the second tubular section of filter media322into the outlet flow path244, where it meets up with fluid that has flown through the first tubular section of filter media266in which it then flows into the filter head292and out through the pump outlet port386.

If the second filter element234becomes occluded, or in the condition of a cold-start, the inner bypass valve arrangement240may be opened. In such a state, the fluid flows from the second open filter interior328, into the inner container volume308, through the screen360, and into the outflow path244.

After a period of operation, the filter arrangement230will need of servicing. To service the filter arrangement230, the filter housing250is removed from the filter head292. The filter housing250contains the filter housing254. If the filter arrangement230is a spin-on filter, then the entire housing250plus filter cartridge264is disposed of and replaced with a new filter housing250having a new filter cartridge264. If, alternatively, the filter arrangement230is a bowl-cartridge filter, then the filter cartridge264is removed from the housing filter250, and a new filter cartridge264is replaced with the same old housing. The new filter arrangement330is then operably-mounted onto the filter head292.