More particularly, it relates to filters for liquids with one closed end cap designed to hold a removable alignment fin.

Background of the Invention Filter cartridges are typically sold for use in a reusable housing, such as a stainless steel or plastic tank or housing such as a CHEMGARD 0 plastic housing or a PS-1 stainless steel housings available from Millipore Corporation of Bedford, Massachusetts or are sold in a sealed disposable housing.

In the filters sold for use in the reusable housing, the cartridge typically is an elongated cylinder with fluid flowing either from the outside through the filter to a central collection tube or vice versa. One end is capped with a solid or impermeable cap and the other end is typically open and attached by 0-rings, threads or other such devices to a fluid port of the housing to allow the fluid to either flow to or from the filter.

Depending upon the number of cartridges contained in the housing, the rate of flow, the fluid characteristics of the fluid used, the design of the system and other such characteristics, the closed end cap may have an alignment fin molded into its upper surface.

This fin functions to maintain the alignment of the cartridge in the housing during use.

Currently, the same filter is offered in two designs, one with the alignment fin as an integral, non-removable part of the cartridge, the other without any fin. This means that a user of such a product must order and maintain the correct inventory of filters with the appropriate configuration (finned or unfinned). Often cartridges with a fin will not fit into housing designed to be used with cartridges that use no fin. Likewise, a cartridge that requires a fin for alignment cannot use a cartridge without a fin or a spacer without the risk of failure.

Additionally, on those cartridges that do not have a fin, spacers are available from the cartridge manufacturers and are simply placed loosely on top of the closed end of the cartridge to make up the space in the housing. Often these move during use, especially in systems which incur pulsed flows or are subject to vibrations. Their movement causes the filter to drop out of its position within the housing that cause leakage of unfiltered material into the downstream filtrate flow. Likewise spacers are sometimes placed in an upside-down configuration causing the same results.

Because of these deficiencies, the life of some cartridges is shorter than its planned life as it cannot be interchanged into a different process or housing. Further, the fin is typically formed in only one design that may not be optimum for the desired fluid flow in the system.

Lastly, the use of a free spacer is unacceptable due to the issues it raises in use.

What is desired is a cartridge that allows for the use of an alignment fin or spacer when needed and the removal of the fin or spacer when not needed. Also, the need for a cartridge that offers different fin or spacer designs or closed end designs would allow for the optimization of the fluid flow in any given system. Moreover, there is a need for a way to secure the spacer to the closed end of the cartridge so that it does not become dislodged during insertion or use.

Lastly, there is a need to reduce inventory on hand and a cartridge that allows one to do so is greatly needed. The present invention provides such a device.

Summary and Objects of the Invention The present invention is a filter cartridge having a detachable alignment fin mounted to the closed end of the cartridge. The fin may be just a fin or it maybe a spacer as well.

The fin may be formed as part of the end cap and have a device for its removal such as a series of perforations or one or more score lines formed at the intersection of the end cap end surface and the fin.

Alternatively, the end cap may contain a retainer for holding the fin to the cap if and when desired. The retainer may be a threaded device, a locking lug or bayonet device or a snap-fit ring device. It may be raised above the surface of the cap such as on a pedestal or recessed within the cap so long as it does not interfere with the sealing integrity of the cap. This embodiment also allows for the use of various fin designs that can be used to optimize fluid flow characteristics. Optionally, there is provided a flat cap attachment that is used when no fin is attached so as to provide the flow characteristics as a flat cap filter.

It is an object of the present invention to provide a filter cartridge comprising a filter element having a first and second end and a length that is equal to or greater than its diameter, a first opening in the first end of the element, a second opening in the second end of the element, a first end cap liquid sealably secured to the first end of the element and a second end cap sealably secured to the second end of the element, the first end cap having a central opening, the second end cap having an impermeable end portion and a retention device for the selected retention of an alignment fin.

It is a further object of the present invention to provide a filter cartridge comprising a cylindrical filter element having a first and second open end at opposite ends of the cylinder, a first end cap sealed to the first open end of the filter element, the first end cap having opening allowing fluid communication to interior of element, a second end cap secured to the second end of the element, the second cap being sealed so as to prevent fluid communication between exterior and interior through the second opening and wherein the second cap has an alignment fin releasably secured to and arising out of the second cap end outer surface.

It is a preferred object of the present invention to provide a filter cartridge comprising a cylindrical filter element having a first and second open end at opposite ends of the cylinder, a first end cap sealed to the first open end of the filter element, the first end cap having opening allowing fluid communication to interior of element, a second end cap secured to the second end of the element, the second cap being sealed so as to prevent fluid communication between exterior and interior through the second opening and wherein the second cap has a retention device for an alignment fin wherein the retention device is selected from the group consisting of perforations, one or more score lines, lug holders, bayonet holders, threads and snap-fit retainers.

It is another object of the present invention to provide a filter cartridge comprising a cylindrical filter element having a first and second open end at opposite ends of the cylinder, a first end cap sealed to the first open end of the filter element, the first end cap having opening allowing fluid communication to interior of element, a second end cap secured to the second end of the element, the second cap being sealed so as to prevent fluid communication between exterior and interior through the second opening and wherein the second cap has an alignment fin secured to and arising out of the cap end, the intersection between the root of the fin and the top surface of the end cap having a releasing device for the fin selected from the group consisting of a series of perforations and one or more score lines.

It is an object of the present invention to provide a filter cartridge comprising a filter element having a first and second end and a length that is equal to or greater than its diameter, a first opening in the first end of the element, a second opening in the second end of the element, a first end cap liquid sealably secured to the first end of the element and a second end cap sealably secured to the second end of the element, the first end cap having a central opening, the second end cap having a impermeable end portion and a retention device for the selected retention of an alignment fin, the retention device being proud of the outer surface of the end.

It is an object of the present invention to provide a filter cartridge comprising a filter element having a first and second end and a length that is equal to or greater than its diameter, a first opening in the first end of the element, a second opening in the second end of the element, a first end cap liquid sealably secured to the first end of the element and a second end cap sealably secured to the second end of the element, the first end cap having a central opening, the second end cap having a impermeable end portion and a retention device for the selected retention of an alignment fin and the retention device being recessed within the outer surface of the end.

In the Drawings Figure 1 shows a device according to the prior art, in cross section.

Figure 2 shows a first embodiment of the present invention in cross section.

Figure 3 shows a second embodiment of the present invention in cross section.

Figure 4 shows a third embodiment of the present invention in cross section.

Figure 5 shows a fourth embodiment of the present invention in cross section.

Figure 6 shows the embodiment of Figure 5 in a top down view.

Figures 7A-F shows various fin configurations that can be used in the present invention.

Figures 8A and B show another embodiment of the present invention.

Figure 9 shows another embodiment of the present invention in cross section.

Figure 10 shows a further embodiment useful in the embodiment of Figure 9 of the present invention in cross section.

Detailed Description of the Invention In Figure 1 is shown a filter cartridge 1 according to the prior art that has a filter element 2 having two ends 3,4. The first end 3 is sealed by an end cap 5. The second end 4 is sealed by end cap 6. The first end cap 5 has an opening 7 that allows for fluid to flow from the exterior 8 of the cartridge to the interior 9 of the cartridge or vice versa without having to flow through the element 2. This typically forms either the inlet or more preferably the outlet from the cartridge. The second end cap 6 has an alignment fin 10 permanently secured to and formed as part of the second end cap 6. The second end cap 6 is solid, having no opening and therefore all fluid that is to enter the interior of the filter element 2 must do so either through the porous element 2 or the opening 7 of the first end cap.

In Figure 2 is shown a first embodiment of the present invention. The cartridge 11 has a filter element 12 having two open ends 13 and 14. The first opening 13 is sealed by an end cap 15. The second opening 14 is sealed by an end cap 16. The first end cap 15 has an opening 17 that allows for fluid to flow from the exterior 18 of the cartridge 11 to the interior 19 of the cartridge 11 or vice versa without having to flow through the element 12. This typically forms either the inlet or more preferably the outlet from the cartridge 11. The second end cap 16 has an alignment fin 20 releasably secured to the second end cap 16. As shown in this embodiment, the fin is attached to the end cap16 by a plastic portion formed between the root 21 of the fin 20 and the outer surface 22 of the end cap 16. This portion contains a device for the easy removal of the fin if desired. Such a device includes but is not limited a series of perforations 23 as shown or one or more score lines (not shown) which allow for a thinning of the plastic portion at the root 21 so that the fin may be removed by cutting or mechanical twisting.

In Figure 3 is shown another embodiment of the present invention. In this embodiment, the fin 30 is attached by a retainer 31 to the end cap 32. All other elements of Figure 3 are the same as those as in Figure 2 and provide the same function and therefore have been accorded the same number designation. As shown the retainer 31 is raised above or is proud of the outer surface 33 of the end cap 32. Also as shown the retainer is formed as a series of threads 34 that correspond to a series of threads 35 formed within a recessed portion 36 of the fin 30 itself. Instead of threads other well known retention devices such as 0-rings, bayonet mounts, undercuts with corresponding detents and simple friction fittings may be used to retain the fin to the end cap in a secure but removable manner.

As shown in Figure 4, the retainer 41 is recessed into the surface 42 of the cap 43 and retains an extension 44 formed on the fin 45 itself so as to hold the fin 45 to the end cap 43. As with the embodiment of Figure 3, other well-known retention devices may be used in lieu of the threads that are shown.

In Figure 5 is an embodiment in which the fin 51 is retained to the end cap 52 by one or more snap or locking devices 53. As shown in this Figure, the fin 51 has a portion 54 that extends beyond the edge 55 of the end cap 52. A second portion 56 extends downwardly from the first portion 54 and has a lip 57 that extends inwardly and secures the fin 51 to the end cap 52 by locking the fin 51 under the end cap 52. The portion 54 may be a single continuous portion or it may be divided into two or more segments. As shown in Figure 6, it is three segments.

In the embodiments of Figures 2-5 one may use a variety of fin configurations as shown in Figures 7A-F. Figure 7A shows a traditional fin configuration of three fin segments 71 spaced equally apart from each other and having an angle along its outer surface as determined relative to the horizontal plane of the end cap 72 of about 45°. One may use a lesser or greater number of fin segments. Preferably one uses between 1 and 5, more preferable between 2 and 5 fin segments. Likewise, one may use one or more fin segments having an angle of less than or greater than 45°. Preferably the angle used is between about 22° and about 75°, more preferably from about 30° to about 60°. Figure 7B shows two fin segments 73 having an angle of about 60°.

Alternatively, as shown in Figure 7C, one may use a fin design in which the one or more segments 74 are spirale or arranged on an angle along its outside length so as to cause turbulence in the fluid as it passes the one or more fin segments 74.

In another embodiment, shown in 7D, one may use a conical 75 cap in lieu of fin segments. In the same vein, one may use a dimpled conical cap 76 as shown in 7E or a bullet shaped cap 77 as shown in Figure 7F. The design of the fin is not critical to the present invention and may be any which is useful to one of ordinary skill in the art.

Moreover, in the embodiments of Figures 3 and 4, one may alternatively use a flat end cap cover of Figure 8 A and B if no fin is desired.

In another embodiment, as shown in Figure 9, the fin is in the form of a spacer 91. It may be attached to the end cap by any of the means discussed above. Preferably, it is formed as a separate attachable device using the one or more snap or locking devices 92 similar to that described in Figure 5. As shown in this Figure, the spacer 91 has a portion 93 that extends beyond the edge 94 of the end cap 95. A second portion 96 extends downwardly from the first portion 93 and has a lip 97 that extends inwardly and secures the spacer 91 to the end cap 95 by locking the spacer/fin 91 under the end cap 95. The locking device (s) 92 may be a single continuous portion or it may be divided into two or more segments. Preferably, it is of three equal segments that are equally spaced apart from each other. The spacer also has 1 or more openings 98 in the top and/or side of the spacer to allow for liquid flow. In this embodiment 3 are shown in the sides of the spacer. Preferably, they are of equal size that are equally spaced apart from each other. Additionally, one may also incorporate one or alignment fin segments 99 to the spacer as shown in the Figure.

Figure 10 shows another configuration of a fin that acts as a spacer 100. In this embodiment, the spacer has a hollow center 101 and two openings 102 in the opposite sides of the spacer to allow for fluid flow. No alignment fin segments are shown in this although they can be used if desired. The attachment means can be any of those described previously. For simplicity in drawing the Figures, that design of Figure 9 has been chosen.

The spacer is retained to the cartridge and acts as the device which takes up any space between the closed end of the cartridge and the end of the housing, such as a CHEMGARD 0 plastic housing or a PS-1 stainless steel housings available from Millipore Corporation of Bedford, Massachusetts. The size (height) of the spacer is dependent on the amount of space which needs to be made up. Typically, they are in 2 inch (5.08cm) increments (2,4 or 6 inch (5.08,10.16 and15. 24 cm) sizes are typical) although other sizes are possible.

They are designed to snuggly fit the cartridge into the larger housing and keep it from being dislodged during handling and use. The use of openings such as 98 in Figure 9 or 102 in Figure 10 ensure that the fluid is free to circulate in the housing in the manner that occurs with a cartridge of the correct size for that housing so as to provide the same effect as a correct sizes cartridge.

The fin may be formed of any plastic material and is preferably formed of the same plastic material as the closed end cap of the filter. Typical plastics that may be used include but are not limited to polyolefins such as polyethylene, polypropylene, EVA copolymers, PTFE resin, PFA and other thermoplastic perfluorinated resins, polystyrene, polycarbonates, nylon and other polyamides and PVDF as well as thermosets such as epoxies or urethanes. When using the snap-fit configuration, it is preferred that the plastic chosen is somewhat resilient to allow for the fin cover to bend and fit over the lip of the end cap.

Example A fin cover in the configuration of Figure 5 was made of polyethylene and attached to a 10 inch CHEMGUARD@ cartridge available from Millipore Corporation of Bedford, Massachusetts. The fin was found to easily attach to the closed end cap and was retained during normal use for the cartridge using water as the test fluid. The cover also was easily removed after the test was completed.