Filter with improved fatigue performance and torque transfer

[0001] This patent application claims the benefit of U.S. Provisional Patent Application No. 60/640,076, filed Dec. 29, 2004, which is incorporated herein by reference in its entirety.

[0002] The present invention generally relates to filters and more particularly relates to high strength filters which may be used for high pressure fluids.

[0003] Hydraulic spin-on fluid filters are well known in the art and are typically used for the purpose of filtering hydraulic working fluid in the hydraulic circuit of an engine and/or vehicle. Such hydraulic fluid filters typically comprise an end plate either stamped or cast of metal material. A cylindrical drawn metal canister is secured directly or indirectly to the end plate (e.g. indirect attachment can be done by way of a seaming lid, which also serves to retain an external seal) and a suitable filter element contained therein. The filter element often includes cylindrical pleated filter media, but may also be any other form of suitable filtering media. The end plate of the filter usually includes a central threaded hole which serves as means to provide at least one fluid port for the filter element and also provides a means for mounting and threadedly fastening the filter to the mounting adaptor of a fluid circuit. Examples of such fluid filters are shown for example in U.S. Pat. Nos. 5,906,740; 5,453,195; 5,490,930; 5,906,736; and 6,554,140. Since the present invention relates to improvements over these prior designs, and may be incorporated into these designs, the patents are hereby incorporated by reference.

[0004] As it pertains to high pressure spin-on type filters, there are several different considerations in the design of the filter. For example, the '740, '195 and '930 patents referenced above discuss the importance of having high strength to resist high pressure when in use (both burst strength and cyclical fatigue strength). It is also known to connect the end plate or base plate to the canister directly thereby avoiding the use of a separate seaming lid to facilitate a connection to reduce the number of parts. However, in doing so, a significant consideration when attaching the end plate directly to the cylindrical side wall of the canister is how best to torsionally lock the end plate to the canister since installation and removal of the filter requires spinning the canister and transferring torque from the canister to the end plate. This is necessary to drive the internal threading formed into the end plate onto and off the threaded stub of a mounting adaptor for the fluid circuit. One such technique, for example, is proposed in the '740 patent, as shown, for example, in FIGS. 8-10.

[0005] There are multiple aspects of the present invention for which separate and independent patent coverage is sought as represented by the claims appended hereto

[0006] One aspect of the present invention relates to an improved mechanism for providing torque transfer between an end plate and the canister of a filter. According to this aspect, an end plate may have thread means for releasable mounting of the filter; and port means for inletting and outletting fluid into and out of the filter. The filter may also include a canister having an annular side wall with a closed end portion. The annular side wall of the canister extends axially from the closed end portion to the end plate and extends around an outer periphery of the end plate. The side wall may include an annular terminating lip portion that is wrapped radially inward over the end plate. Contained within the canister and end plate is filtering means comprising suitable filtering media for filtering fluid. At least one notch is formed into the outer periphery of the end plate and a locking portion of the side wall portion is formed radially inwardly into locking engagement with the at least one notch, thereby providing an improved torque transfer means between the end plate and the canister.

[0007] A further aspect of the present invention is directed toward a filter having improved cyclical fatigue resistance. In accordance with this aspect, a filter may include an end plate having port means for inletting and outletting fluid into and out of the filter and a canister having an annular side wall with a closed end portion. The annular side wall of the canister extends axially from the closed end portion to the end plate and extends around the outer periphery of the end plate. The side wall may include an annular terminating lip portion that is wrapped radially inward over the end plate. Contained in the canister is filtering means comprising suitable filtering media for filtering fluid. An annular trough may be formed in the end plate along an exterior surface thereof for receipt of the terminating lip portion. The annular trough may have a bottom, an inside annular wall and an outside annular wall. The outside annular wall may diverge outwardly from the bottom in a substantially oblique manner relative to the annular canister side wall. The outside annular wall trough may form an outer peripheral retention corner which is rigid and has sufficient thickness or radial width at its base to provide for strength and to prevent breakage of the end plate outer periphery while also being very narrow or radially thin at the top or corner so as to provide a very short contact surface which engages the terminating lip portion. An advantage of this configuration is that the moment forces induced on the terminating lip portion of the canister are reduced during pressure loads imposed upon the canister which thereby improves fatigue resistance and overall strength of the filter.

[0008] Other aspects and advantages of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.

[0016] While the invention will be described in connection with certain preferred embodiments, there is no intent to limit it to those embodiments. On the contrary, the intent is to cover all alternatives, modifications and equivalents as included within the spirit and scope of the invention as defined by the appended claims.

[0017] Referring to FIG. 1, an embodiment of a filter 10 is shown in the various drawings for use with a mounting adaptor 12 of a fluid circuit. The mounting adaptor 12 is shown in dashed lines to make clear that the mounting adaptor is not part of the invention, but merely shown to illustrate the environment in which the subject filter 10 may operate and how the filter 10 can be spun on and threadedly connected to the mounting adaptor 12 and a fluid circuit.

[0018] The filter 10 may include several components including an end plate embodiment in the form of a cast metal base plate 14, a deep drawn steel canister 16, an internal filter element 18, a coil spring 20 and various internal and external ring seals 24, 26, 28. The filter element 18 may comprise suitable filtering media 30 (such as pleated filter paper, fiberglass filtering media, or other such suitable media), a central perforated tubular support 32, and top and bottom end caps 34, 36 which are potted or otherwise sealingly secured to opposed ends of the filtering media 30. The top end cap 34 may include a central opening to provide for fluid passage therethrough. The bottom end cap 36 may be closed and may be urged upwardly by the coil spring 20 such that the filter element 18 is biased toward and against the base plate 14. The internal seal 24 may be provided between the base plate 14 and the filter element 18 for purposes of preventing short circuiting of unfiltered fluid along the inner periphery of the filter element between the base plate and the filter element.

[0019] The canister 16 may include a closed dome-shaped end 38 and a cylindrical side wall 40 extending axially therefrom toward the base plate. The side wall 40 may extend up and around an outer cylindrical periphery of the base plate 14 and may include an outer annular terminating lip portion 42 that is deformed radially inward and wrapped over the top end face of the base plate 14 to directly secure the base plate 14 to the canister 16.

[0020] The base plate 14 may be cast from metal material such as aluminum, but could also potentially be a stamped steel component, or otherwise appropriately formed. Referring to FIG. 3, the base plate 14 may include a central hub 44 and an outer peripheral annular rim 46 which are connected together by ribs 48 extending radially therebetween. The central hub 44 may include a threaded central opening 50 which also provides for an outlet port 52. Referring to FIG. 2, the void space between adjacent ribs 48 provides for various inlet ports 54 arranged radially around the central hub 44.

[0021] The inlet and outlet ports 52, 54 provide means for inletting and outletting fluid into and out of the fluid filter, although it will also be appreciated that it is also known to have a single threaded opening to facilitate inlet and outlet means such as shown, for example, in some of the aforementioned referenced patents. Thus, in other embodiments, such alternate port means for inletting and outletting fluid may be used.

[0022] Referring to FIG. 1, the outer peripheral rim 46 of the base plate 14 may include an external annular groove 56 which receives the external seal 28 for providing a seal between the filter 10 and the mounting adaptor 12. The base plate may also include an outer peripheral groove 58 which receives an internal seal 26 for purposes of sealing between the base plate 14 and the canister 16 to prevent fluid leakage therebetween.

[0023] Referring to FIG. 4, the outer peripheral rim 46 of the base plate 14 may include an annular trough 60 formed into the top or external side of the base plate 14. This annular trough 60 may include an inner annular wall 62, an outer annular wall 64 and a bottom 66. The outer annular wall 64 diverges outward from the bottom 66 in a substantially oblique manner relative to the annular side wall of the filter cartridge to form an outer peripheral retention corner portion 68. This corner portion 68 may be wider at the base and narrower at the top or end such that the corner portion 68 is structurally strong and not prone to breakage or fracture while at the same time a very narrow contact surface is provided for engagement with the terminating lip portion 42 of the filter 10. This short engagement or contact interface 70 shortens the lever arm and thereby moment loads when fluid pressure in the canister tends to urge the canister away from the base plate.

[0024] Referring to FIG. 6, the contact interface 70 extends radially inward toward the filter center a distance measured from the outer cylindrical periphery 72 of the base plate 14 (namely, the radial width) a distance 74. In a first embodiment, the distance 74 may be about 0.02 inches given about a 1.5-2.5 inch radius base plate. In a second embodiment, the distance 74 may be less than 0.03 inches. In a third embodiment, the distance 74 may be less than 0.05 inches. In a fourth embodiment, the distance 74 may be less than 0.07 inches. To provide for strength of the corner portion 68, the outer wall 64 extends in a substantially oblique manner. This may be accomplished in a number of ways. Although a generally flat inclined surface of the outer wall 64 is shown extending from the bottom 66 to the contact interface 70, it will be appreciated that this shape may be curved, irregular or the like and still encompassed within the context of the present invention.

[0025] The outside annular wall 64 may create a geometry or configuration with an axis 76 measured from the trough bottom 66 to the innermost point of contact between the retention corner portion 68 and the terminating lip portion 42 (e.g. where the contact face terminates at its inner diameter), which axis 76 forms an acute angle 78. In a first embodiment, the angle may be 78 between about 55 and 65 degrees relative to the side wall. In a second embodiment, the angle 78 may be greater than about 50 degrees. In a third embodiment, the angle 78 may be greater than about 35 degrees.

[0026] Referring to FIGS. 3 and 4, at least one notch 80 may be formed into the outer periphery of the base plate for providing a locking torque mechanism. In one embodiment, multiple notches 80 are arranged in an annular array radially around the outer periphery of the peripheral rim 46 of the base plate 14 as shown, for example, in FIG. 3. The notches 80 may be cast or stamped into the base plate 14 or can be machined or cut out.

[0027] Referring to FIG. 5, the side wall may include an inwardly deformed annular bead 82 which may include a locking portion 84 which is partially and radially received into each notch 80 and interferes with the shoulder 86 which is formed at each terminating edge of the notch 80. This is shown schematically in FIGS. 4 and 5 where dotted lines are illustrated to show where the outer cylindrical periphery of the base plate 14 would extend, but for the formation of the notch 80, thus showing a slight radial interference indicated at 88. This provides for a torque locking mechanism between the base plate 14 and the canister 16. The notches 80 may include a generally planar bottom 90 and an arch-shaped side wall 92, opposing ends of which form the shoulders 86. In one embodiment, this arrangement is located below the provision of the internal seal 26 and at the bottom outer peripheral corner of the base plate, but it may also be done at other outer peripheral locations. It will be appreciated, however, other shapes and configurations for the notches may also be used.

[0028] Another embodiment of a filter is shown in FIGS. 7 and 8. The filter 110 is similar to filter 10 except that the base plate 114 has a different shape for the trough 160. The trough 160 may include an inner wall 162, an outer wall 164 and a bottom 166. The outer wall 164 diverges outward from the bottom 166 in a substantially oblique manner relative to the annular side wall of the filter cartridge to form a retention corner portion 168.

[0029] This corner portion 168 may be wider at the base and narrower at the top or end such that the corner portion 168 is structurally strong and not prone to breakage or fracture while at the same time a very narrow contact surface is provided for engagement with the terminating lip portion 142 of the filter 110. This short engagement or contact interface 170 shortens the lever arm and thereby moment loads when fluid pressure in the canister tends to urge the canister away from the base plate.

[0030] Referring to FIG. 8, the contact interface 170 extends radially inward toward the filter center a distance measured from the outer cylindrical periphery 172 of the base plate 114 (namely, the radial width) a distance 174. In a first embodiment, the distance 174 may be about 0.02 inches given about a 1.5-2.5 inch radius base plate. In a second embodiment, the distance 174 may be less than 0.03 inches. In a third embodiment, the distance 174 may be less than 0.05 inches. In a fourth embodiment, the distance 74 may be less than 0.07 inches. To provide for strength of the corner portion 168, the outer wall 164 extends in a substantially oblique manner. This may be accomplished in a number of ways. Although a generally flat inclined surface of the outer wall 164 is shown extending from the bottom 166 to the contact interface 170, it will be appreciated that this shape may be curved, irregular or the like and still encompassed within the context of the present invention.

[0031] The outside annular wall 164 may have an angle 178 measured from the trough bottom 166 to the innermost point of contact between the retention corner portion 168 and the terminating lip portion 142 (e.g. where the contact face terminates at its inner diameter). In a first embodiment, the angle may be 178 between about 55 and 65 degrees relative to the side wall. In a second embodiment, the angle 178 may be greater than about 50 degrees. In a third embodiment, the angle 178 may be greater than about 35 degrees.

[0032] In this embodiment, the inner wall 162 has a curved portion 163 and a straight portion 165. The curved portion 163 may curve upwardly toward the end of the filter. The straight portion 165 may be vertical and substantially parallel to the sidewall 140. The curved portion 163 may be located between the bottom wall 166 and the straight portion 165. In this embodiment, the bottom wall 166 is relatively flat.

[0033] All references, including publications, patent applications, and patents, cited herein are hereby incorporated by reference to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein.

[0034] The use of the terms “a” and “an” and “the” and similar referents in the context of describing the invention (especially in the context of the following claims) is to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The terms “comprising,” “having,” “including,” and “containing” are to be construed as open-ended terms (i.e., meaning “including, but not limited to,”) unless otherwise noted. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention.

[0035] Preferred embodiments of this invention are described herein, including the best mode known to the inventor(s) for carrying out the invention. Variations of those preferred embodiments may become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventor(s) expect skilled artisans to employ such variations as appropriate, and the inventor(s) intend for the invention to be practiced otherwise than as specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context.