Spin-on filter assemblies

[0002] The present invention is directed to spin-on filter assemblies. More particularly, the present invention is directed to high pressure, spin-on filter assemblies which are optionally rebuildable.

[0003] Spin-on filter assemblies are used for a number of purposes such as, but not limited to, filtering hydraulic fluid, filtering lubrication oil for machinery and internal combustion engines and for filtering transmission oil.

[0004] Primarily applications for such filters are high-pressure hydraulic systems which use spin-on filters. These filters have housings which are usually made of steel and are high volume items sold for both the original equipment and replacement market. Lately, there has been considerable interest in providing filter assemblies in which the filter housing is reusable. There are of course environmental concerns which arise when a used filter having hydraulic oil, or any other filtered liquid therein, is disposed of in its entirety because not only does the filter housing end up in a land fill, but also the filter media and liquid within the housing. In some situations, this is still acceptable, but in other situations it is not. Accordingly, there is a need for filter assemblies which are in effect rebuildable by removing the filter element which contains the filter media therefrom so that the only item which must be disposed of is the filter media itself. When the housing is opened, hydraulic fluid therein can be drained therefrom, refined and reused or disposed of in an acceptable manner, instead of being disposed of while contained within a filter housing.

[0005] Generally, it is preferable to have as few parts for a particular item as necessary. According to current practice, one spin-on filter assembly is manufactured for situations in which the entire assembly is disposed of and another spin-on assembly configuration manufactured for rebuildable spin-on filter assemblies. This results in an overall increase in cost.

[0006] In view of the aforementioned considerations, the present invention is directed to a filter assembly comprising an annular can having a first closed end and a second open end. The second open end has a coupling arrangement adjacent thereto for receiving a first base member which is not removable therefrom when coupled thereto, so as to provide filter assembly which is disposed of in its entirety with a used filter media inside, and a second base member which is removable from the can to provide a rebuildable filter assembly in which only the used filter media therein is disposed of.

[0007] More specifically, the present invention is directed to a filter assembly comprising a can having first and second ends, the first end being closed and the second end being open, wherein the can is adapted to receive a filter element. The can has an interior wall surface and coupling portion adjacent the second end of the can, wherein the coupling portion has a radially disposed, annular groove therein and an helically threaded section inboard of the groove disposed about a first axis. A base having openings therethrough adapted to provide inlet and outlet openings for fluid being circulated through the housing and through the filter element within the housing. The base has an externally threaded portion disposed about a second axis for receipt in the internal helically threaded section of the internal wall surface of the can with the first and second axes being coexistant. The base also has a radially projecting rib for receipt in the annular groove in the wall of the can to lock the base within the can, whereby the filter element is retained in the can between the first and second ends thereof. In accordance with a first arrangement, the base is permanently fixed with respect to the can and in accordance with a second arrangement the base is removable from the can so that the element can be replaced.

[0008] In order to facilitate interchangeability bases, the groove in the can, is V-shaped with one of the bases having a rib which compliments the V-shaped groove, allowing the first base to be unscrewed, and the other of the bases having a rib, which compliments only one surface of the V-shaped groove, so as to prevent the other base from unscrewing from the can.

[0009] Various other features and attendant advantages of the present invention will be more fully appreciated as the same becomes better understood when considered in conjunction with the accompanying drawings, in which like reference characters designate the same or similar parts throughout the several views, and wherein:

[0010] FIG. 1 is a side view elevation showing a can and base of a spin-on filter assembly separated from one another prior to being assembled in accordance with the principals of the present invention;

[0011] FIG. 2 is a side elevation of the spin-on filter of FIG. 1 showing the can and base assembled to hold a filter element within an enclosure formed thereby;

[0012] FIG. 3 is an enlarged side view showing a base with a separable lock rib in accordance with the first aspect of the present invention;

[0013] FIG. 4 is a side view showing the base with a rib providing an inseparable lock tab in accordance with a second aspect of the invention.

[0014] Referring now to FIGS. 1 and 2, there is shown a can 10 and a base 12 coaxial with axes 13 and 13′, respectively, which when assembled form a housing 14 that encloses a filter element 16 having a filter media 17. Both the can 10 and base 12 are made of a durable impact and solvent resistant plastic material so as to form a robust filter assembly useful as a spin-on filter in high pressure systems, such as for example, high pressure hydraulic systems.

[0015] The can 10 has a first end 20 and a second end 22 with the first end 20 being closed with a dome 24 and the second end having an opening 26 therethrough. Adjacent to the second end 22 of the housing 14 there is an end surface 28 having an axially extending annular rib portion 30. Adjacent the annular rib 30 is an inner wall 32 which begins with inwardly tapering, frustoconical surface 34. After a short axial section 36, a substantially V-shaped groove 38 occurs, the V-shaped groove having the first frustoconical surface 40 a second frustoconical surface 42 separated by a very short cylindrical surface 44 that forms at the bottom of the groove 38. Adjacent the V-shaped groove 38 is a cylindrical surface 46 and just inboard of the cylindrical surface 46 is a threaded wall portion 48. The remaining portions 50 of the internal wall surface is a smooth cylindrical surface.

[0016] The base 12 has a first end 60 and a second end 62. First end 60 is inserted through the open end 26 of the can 10, while the second end 62 overlays the end surface 28 of the can with a flange 64, which flange has channel 66 in which is seated a sealing gasket 68.

[0017] The base 12 has central threaded bore 70 which is aligned with a collar portion 72 that projects from the first end 60 of the base and four, spaced openings 74 which are separated by four axially extending ribs 76 that form supports for holding the filter element 16 in spaced relation to the end surface 78 of the second end 60 of base 12. Just out-board of the four radial openings 74 is an annular groove; 80 which receives a gasket (not shown) in order to seal the base 12, and thus the filter assembly with a machine, such as a hydraulic machine (not shown).

[0018] Adjacent the end surface 78 of the base 12 there is a threaded portion 82, which is seen in FIG. 2 meshes with the threaded portion 48 on the internal wall 32 of the can 10. Just inboard of the threaded portion 82 there is short cylindrical portion 84 and beyond the cylindrical portion there is a locking rib 86. The locking rib 86 can have two configurations. The first configuration is shown in FIG. 3, and the second configuration is shown in FIG. 4.

[0019] The rib 86 of FIG. 3 serves as a separable lock tab wherein the rib 86 has a first frustoconical surface 90 which diverges from the second axis 13′ of the base 12 and a second frustoconical surface 92 which converges toward the axis 13′. These surfaces meet at a substantially cylindrical section 94 (which could also be slightly arcuate). The locking surface 90 has less of a lead angle then the arcuate surface 92 so that the lead angle entering the can 10 is less then that exiting the can. Consequently, more torque or force is required to assemble the filter then to disassemble the filter.

[0020] In the arrangement of FIG. 4, the frustoconical surface 92 of rib 86 in FIG. 3 has been replaced by the flat radially extending surface 96 of rib 86′ which is perpendicular to the axis 13 of the base 12. Consequently, it is not possible to engage the frustoconical surface 40 of the groove 38 in can 10 with a camming surface that spreads the open end 26 of the can 10 slightly apart so that the base 12 can be unscrewed from the can. Consequently, rib 86′ provides an inseparable locking tab because no lead angle is provided on the rib 86′ for applying a camming force to spread the opening 26 of the can 10, so that upon turning the base 12, the base can retreat away form the can as the base is rotated with respect thereto. Consequently, by slightly altering the geometry of the rib 86, either a separable locking tab 86 is created or an inseparable locking tab 86′ is created.

[0021] As is readily seen in FIG. 2, a robust filter assembly is created in which the can 10 is tightly closed by the base 12 with the annular rib 30 in surface 28 of the can compressing the sealing gasket 68 to seal the can while the rib 86 or 86′ on the base mechanically locks to the can by seating in the V-shaped groove 38.

[0022] An option is thus provided for disposing of the filter element 16 (including the filter media 17) for separate disposal while rebuilding the filter assembly with a fresh filter element. Alternatively, the entire filter assembly may be disposed of if that is an acceptable alternative.

[0023] From the foregoing description, one skilled in the art can easily ascertain the essential characteristics of this invention, and without departing from the spirit and scope thereof, can make various changes and modificaitons of the invention to adapt it to various usages and conditions.