Filter element having inner support and methods

A filter element includes a construction of pleated filter media defining an interior volume. First and second opposite end caps are secured to opposite ends of the filter media. A support structure supports the filter media and is operably oriented in the interior volume. The support structure extends from the first opposing interior face to the second opposing interior face. The support structure is provided to extend less than a full extension between the first end cap and second end cap.

TECHNICAL FIELD

This disclosure concerns a filter element of pleated media having a porous support structure. This disclosure also concerns a dust collector utilizing these filter elements and method of pulse cleaning the filter elements.

BACKGROUND

Filter elements of pleated media are often arranged in a tubular construction. By the word “tubular”, it is meant a closed loop, which can be round, non-round, oval, elliptical, racetrack shaped, etc. The filter elements can be used in a variety of applications such as cleaning the air intake for compressors or filtering the air in dust collectors. In many cases, the fluid to be filtered flows from the exterior, through the pleats, and into the open interior volume of the tubular construction. In many situations, it is desirable to support the pleated media from within the interior volume of the filter element in order to prevent the pleats from collapsing against themselves in the interior volume. When the tubular construction is oval, elliptical, or racetrack shaped, the problem with having the pleats collapse against themselves is even more of an issue because of the geometry of the cross-sectional shape of the media construction.

One typical approach to supporting the filter media within the interior of the filter includes using an inner filter liner. The inner filter liner is often made from metal and is porous to allow fluid flow there through. There have been uses in the prior art of non-metal inner liners, as well.

When used in dust collectors, filter elements can be periodically cleaned by back flushing the elements through the use of a pulse of compressed gas or air. The durability of the filter elements is important for long filter life. In prior art elements that have an inner liner that extends an entire length between the end caps, the pulse cleaning process can cause stress as the filter media tries to bow outwardly. This may cause a failure point by tearing the media where it is connected to the end caps, or by causing damage by the inner liner to the end caps, leading to premature failure, leak paths, or other problems.

Improvements in filter elements and media support are desirable.

SUMMARY

In accordance with principles of this disclosure, a filter element is provided. The filter element includes a construction of pleated filter media defining an interior volume. First and second opposite end caps are secured to opposite ends of the filter media. A support structure bridges the filter media and is operably oriented in the interior volume. The support structure extends from the first opposing interior face to the second opposing interior face. The support structure is provided to extend less than a full extension between the first end cap and second end cap.

One of the advantages of having the support structure with at least one end freely floating and unattached or disconnected to any other portion of the filter element is that it allows the filter element to expand and contract axially. During pulse cleaning of the filter element, the elements are allowed to have the media bow outwardly (expand) and then return to the original shape, which can be in a dynamic, fast, slapping motion. This helps to clean the filter elements by shaking the dust off of the media.

The support structure may include one of a pleated or extruded construction.

The pleats of each of the support structure of the pleated construction may extend about parallel to the direction of pleats of the pleated filter media.

The pleated construction may comprise a semi-rigid pleated screen.

The support structure may be non-metal.

The first end cap can be an open end cap in communication with the interior volume.

The second end cap may be a closed end cap.

In one or more embodiments, the support structure is secured to the second end cap.

In some arrangements, the support structure is unsecured and free of the first end cap.

In some arrangements, the support structure may include a first section secured to the first end cap, a second section secured to the second end cap, and the element being free of support structure in a region between the first section and the second section.

The support structure may be secured to the first end cap, while the support structure is unsecured and free of the second end cap.

The pleated media may be non-round.

The pleated filter media may be racetrack shaped, having a pair of parallel sides joined by a pair or rounded ends

In one or more embodiments, the filter element is metal-free.

In some arrangements, the filter element is free of inner and outer liners.

In some arrangements, the support structure comprises a metal construction.

In some embodiments, the support structure comprises an extruded construction.

In one or more arrangements, the support structure is an extruded plastic inner liner.

The support structure may include an expanded metal construction.

the support structure may be embodied as an inner liner.

A length of the filter element between the first and second end caps can be at least 2 inches.

A length of the filter element between the first and second end caps can be at least 20 inches and no greater than 100 inches.

In another aspect, a dust collector is provided. The dust collector includes a housing having a dirty air inlet, a dirty air plenum, a clean air outlet, a clean air plenum, and a tubesheet separating the dirty air plenum from the clean air plenum. A plurality of filter elements, as characterized variously above, are removably mounted in the tubesheet.

The dust collector may further include a cleaning system mounted to emit pulses of gas into the filter elements from a downstream side of the filter element to an upstream side to clean the filter elements.

In another aspect, a method of filtering includes providing a dust collector as characterized above. There is a step of directing fluid to flow through the pleated filter media and into the interior volume. While the fluid is flowing through the pleated filter media, there is a step of supporting the filter media to prevent the filter media from collapsing together by using the support structure. The method includes periodically emitting a pulse of gas into the interior volumes of the filter elements and allowing the filter media to expand and axially contract.

It is noted that not all of the specific features described herein need to be incorporated in an arrangement for the arrangement to have some selected advantage according to the present disclosure.

DETAILED DESCRIPTION

FIG. 1illustrates one example application in which the filter element constructed according to principles of this disclosure can be utilized. A dust collector10includes a housing12. The housing12has an inlet14for in taking unfiltered or dirty air, as shown at arrow16. The housing12defines within an interior a dirty air plenum18. The dirty air plenum18is also where a plurality of filter elements20, constructed in accordance with principles of this disclosure, are mounted. The filter elements20will remove particulate (e.g., dust) from the air in the dirty air plenum18.

After passing through the filter elements20, the clean or filtered air flows into a clean air plenum22. The clean air plenum22is also within an interior of the housing12. The clean air flows at arrow24through a clean air outlet26.

A tubesheet28divides the interior of the housing between the dirty air plenum18and clean air plenum22. The tubesheet28is typically made from sheet metal and has a plurality of holes or apertures for holding elements20, such that the filter elements20are removably mounted within the tubesheet28. The filter elements20are removably sealed to the tubesheet28to prevent dirty air from bypassing the filter elements and flowing into the clean air plenum22without being filtered by the filter elements20.

The housing12can have sloped walls30in the dirty air plenum18so that particulate and dust removed from the air will fall by gravity and fall along the sloped walls30. There can be a drum or other type of collector at the base32to remove dirt from the dirty air plenum18.

The filter elements20are periodically cleaned by emitting a pulse of gas, such as compressed air, from the downstream side of the elements20to the upstream side. This is a way of back flushing the filter elements20and removing any dust or dirt that has built up on the upstream side of the filter elements20. In this embodiment, a cleaning system is shown at34. The cleaning system34includes a blowpipe36having a plurality of nozzles38. In this embodiment, there is illustrated one nozzle38for each filter element20. However, in other embodiments, there does not necessarily need to be one nozzle per element. The blowpipe36is in communication with a pressurized air supply40, which is in communication with a header pipe42and pulse valve44. Other embodiments are possible, and this is just one example.

In operation, dirty air will flow through the dirty air inlet14, into the dirty air plenum18, and then flow through at least one of the filter elements20. The filter elements20will filter or remove dirt and particulate from the air. The clean filtered air will flow through a downstream side of the elements20and into the clean air plenum22, before exiting the dust collector10through the clean air outlet26. The filter elements20will be periodically cleaned by emitting a pulse of compressed gas or air from the nozzles38and into the filter elements20by flowing from the downstream side of the elements20into the upstream side of the elements20. When this is done, there will be a pressure differential on each element20from the downstream side to the upstream side. In prior art systems, this pressure differential could cause the filter elements to fail by tearing at either or both end caps. The filter elements20are improvements over the prior art in that the filter elements20are constructed to allow the filter media to expand or bow outwardly and axially contract along its length, without failure along one of the end caps. Advantageous constructions to the filter elements20are explained further below.

FIGS. 2-11are illustrations of an example embodiment of filter element20usable in the dust collector10. The filter element20includes a construction of pleated media50. The pleated media50can be a tubular shape52defining an interior volume54. The tubular shape52can be any shape forming a closed loop, such as round, non-round, oval, ovate, rectangular, elliptical, or racetrack shaped. In the embodiment shown inFIGS. 2-4, the filter element20is racetrack shaped, in that it has a pair of opposite parallel sides56,57joined by curved ends58,59. In the embodiment ofFIGS. 13-16, the filter element20is cylindrical in which the pleated media50is cylindrical having a generally round cross-section.

The pleated media50has a plurality of pleats60. InFIG. 2, only some of the pleats50are illustrated for purposes of clarity. The pleats60, in the embodiment shown, have outer pleat tips61and inner pleat tips62. The outer pleat tips61are along the exterior of the pleated media50. The inner pleat tips62are along the interior volume54. The pleated media50, when in the tubular shape, has first and second opposing faces64,66, which generally correspond to the inner pleat tips62.

The filter element20includes a first end cap72. At an opposite end of the element20, there is a second end cap74. The first end cap72and second end cap74are secured to opposite ends of the filter media50.

In the example shown, the first end cap72is an open end cap having an opening73in communication with the interior volume54. The second end cap74can be opened or closed, and in the embodiment shown, it is a closed end cap.

The pleated media50can be secured to the first and second end caps72,74by, for example, molding the ends of the pleated media50within the end caps72,74. In some examples, the first end cap72and the second end cap74are made from a non-metal, molded material. In some examples, the first and second end caps72,74can be made of other types of material and have the media50secured through the use of a potting material, for example. The end caps72,74are typically made from a urethane material.

The filter element20will typically have a seal structure or gasket to provide an airtight seal between the element20and whatever structure the element20is installed. For example, when used in dust collector10, there will usually be a seal or gasket between the open end cap72and the tubesheet28to form a seal therebetween.

The filter element20further includes a support structure80. The support structure80supports the pleated filter media50. By the term “supports”, it is generally meant a structural mechanism to resist opposing forces. The support structure80prevents pleat collapse and crushing of the filter element20through the interior. By “pleat collapse”, it is meant that the support structure80prevents individual pleats from collapsing inwardly toward the interior volume54of the element20and the element20crushing together through the interior.

The support structure80is operably oriented in the interior volume54of the pleated media50. In many examples, the support structure80supports the pleated media50. It may extend, or bridge between the first opposing interior face64to the second opposing interior face66. For example, the support structure80extends from the first opposing interior face64to the second opposing interior face66to structurally support the pleated media50.

The support structure80functions to structurally support or brace the pleated media50while being operably oriented in the interior volume54. In the embodiments ofFIGS. 2-12, the support structure80is not an inner liner for the pleated media50. In the examples ofFIGS. 2-12, the support structure80can structurally support the pleated media50in the absence of an inner liner, or they may include a supportive rigid inner liner. In some embodiments, the entire filter element20may be inner liner-free. In further example embodiments, the filter element20is both outer liner and inner liner free. In other embodiments, however, as can be seen in connection with the embodiments ofFIGS. 13-16, the support structure80in those embodiments is an inner liner200.

In one or more embodiments, the filter element20includes an inner screen83lining the interior volume54. The inner screen83may be embodied in many forms including either a supportive and rigid inner liner to provide structural bracing of the element20, or in the form of a non-supportive liner that does not structurally brace the element20. In some embodiments, the inner screen83can be non-metal, such as plastic, and porous forming an open grid to allow air flow therethrough. The screen83can extend between and be secured to each of the first end cap72and second end cap74. Alternatively, the inner screen83can extend only partially between the first end cap72and second cap74. In some embodiments, the inner screen83is secured to the second end cap74and extends along the inner pleat tips62partially of the length to the first end cap72. In other embodiments, the inner screen83can be secured to the first end cap72and extend partially of the length to the second end cap74. The inner screen83may comprise a perforated facing.

In accordance with principles of this disclosure, the support structure80extends less than a full extension between the first end cap72and the second end cap74. Preferably, the support structure80has at least one free-floating end that is unsecured or unattached from a remaining portion of the filter element20.

In preferred arrangements, the support structure80is not bonded to the inner pleat tips62. That is, the support structure80is attachment-free or bond-free relative to the inner pleat tips62. The outer pleat tips61are free to bow outwardly during pulse cleaning.

In the embodiment shown inFIGS. 6-8, the support structure80is secured to the second end cap74. In this embodiment, the support structure80is unsecured and free of the first end cap72. As can be seen inFIGS. 6-8, the support structure80is encapsulated and fixed within the second end cap74and extends less than a full extension of a length of the filter element20(between end caps72,74) to the first end cap72. As can be seen inFIG. 7, in this embodiment, there is a space or gap78between a free end81of the support structure80and the first end cap72. The space or gap78is an open volume that is support structure-free. The support structure80is spaced a distance less than 50%, typically less than 25%, and often less than 10% from the first end cap72of the full extension between the first end cap72and second end cap74.

Many arrangements are possible. For example, in the arrangement ofFIG. 10, the support structure80is secured to the first end cap72and is unsecured and free of the second end cap74. InFIG. 10, the support structure80extends more than 50% and less than 99% of the full length between the first end cap72and second end cap74. For example, the support structure80can extend between 80% and 98% of the full length between end cap72and end cap74.

In the embodiment ofFIG. 11, the support structure80includes a first section82secured to the first end cap72and a second section84secured to the second end cap74. The filter element20is free of support structure in a support structure-free region86that is located axially between the first section82and second section84. In the example shown inFIG. 11, the region86is about in a center between the first end cap72and second end cap74. It should be understood that the support free region86can be located anywhere along the length between the first end cap72and second end cap74. The region86has a length that is less than 30%, typically less than 20%, and often less than 10% of the overall length between end cap72and end cap74.

The support structure80can be attached to one or more of the end caps72,74through a variety of ways. For example, the support structure80can be molded with the end cap72,74to bond it therewith. The support structure80may also be potted, with a potting material to the end cap72,74. Other ways can be used including using adhesive, bonding agents, or other bonding techniques.

There are many embodiments possible for the support structure80. In the example shown inFIG. 5, the support structure80comprises a pleated construction90. The pleated construction90has at least a partial section with a plurality of pleats92. The plurality of pleats92in the pleated construction90can be extending in a direction that is parallel or non-parallel relative to a direction of pleats60in the pleated filter media50. Preferably, the pleats92extend in a direction parallel relative to the direction of pleats60of the pleated filter media50. In embodiments that include inner screen83, the inner screen83prevent the pleated filter media80from interlocking with the pleats92of the support structure80. In embodiments that include perforated facing or inner screen83, the pleated construction90may include the perforated facing83on opposite sides thereof.

In other embodiments, the direction of pleats92may be angled at a non-zero angle relative to the direction of the pleats60of the pleated filter media50. In one or more embodiments, the angle can be at least 45 degrees, often at least 70 degrees, for example, an angle 80-100 degrees.

The pleats92will typically extend from the first opposing interior face64to the second opposing interior face66of the interior volume54of the pleated filter media50.

The pleated construction90can be made from many types of materials. In preferred constructions, the pleated construction90comprises a semi-rigid pleated screen94. The pleated screen94can be made from plastic or a reinforced cellulose. The pleated screen94has an open screen or mesh to allow for fluid to flow therethrough. Preferably, the pleated construction90has a void volume of no more than 60%.

The overall length of the filter element20between the first and second end caps72,74is often at least 2 inches. In some embodiments, the length can be greater than 50 inches. In many embodiments, the length of the filter element between the first and second end caps72,74is at least 20 inches and no greater than 100 inches. The filter element20can be made from non-metal materials such that it is metal-free.

The pleated construction90will extend less than a full extension between the first end cap72and second end cap74. As explained above, this can be implemented by anchoring one end96of the pleated construction90to one of the end caps72,74while allowing an opposite end98of the pleated construction90to float and be free of connection to the opposite end cap or to any other portion of the filter element20.FIG. 11also shows the embodiment of anchoring the pleated construction90to both end caps72,74but then having a discontinuous region86that is free of support structure80.

One of the advantages of having the support structure80with at least one end freely floating and unattached or disconnected to any other portion of the filter element20is that it allows the filter element20to expand and contract axially. SeeFIG. 9. During pulse cleaning of the filter element20in dust collector10, the elements20are allowed to have the media50bow outwardly (expand, see the broken lines50inFIG. 9) and then return to the original shape (see the solid lines50inFIG. 9), which can be in a dynamic, fast, slapping motion, represented by arrow70. This helps to clean the filter elements20by shaking the dust off of the media50. In prior art elements that have an inner liner that extends an entire length between the end caps, the pulse cleaning process will cause stress as the filter media tries to bow outwardly causing a failure point by tearing the media where it is connected to the end caps, leading to premature failure, leak paths, or other problems. The filter element20avoids this problem because the support structure80has at least one free end that is disconnected, unattached, and freely floating within the element20, allowing the element20to axially contract as the end caps72,74move closer together and the media50bows radially outwardly. The support structure80also prevents pleat collapse.

Another embodiment of support structure80is illustrated inFIG. 12. In theFIG. 12embodiment, the support structure80is an extrusion or injection molded structure. In the example illustrated inFIG. 12, the support structure80comprises a plurality of columns120. The columns120are secured to each other with a plurality of cross braces122. In the example shown, there are two columns124,125spaced from each other. The columns124,125are porous and depicted as hollow cylinders, but could be any shape. The cross braces122are shown perpendicular to the columns, but could be various angles relative to the columns124,125. The columns124,125and the cross braces122can be made from a plastic extrusion or by injection molding. The cross braces122, in the example illustrated, are eight spaced apart from each other, but can be more or fewer. Each cross brace122is shown as ladder shaped in cross-section, with opposite rails being secured to opposite sides of each column124,125.

In the embodiment ofFIGS. 13-16, alternate embodiments of filter elements20are depicted. In these embodiments, the support structure80is an inner core or inner liner200.FIGS. 13-16depict cylindrical elements20having a round cross-section. Pleated media50forms the cylinder and defines an open filter interior54. Lining the filter interior54, adjacent to the inner pleat tips62is the inner core200. The inner core200is typically free and unattached to the inner pleat tips62.

InFIGS. 13-14, the inner core200is non-metal. In some examples, it is plastic. In example embodiments ofFIGS. 13-14, the inner core200is an extruded plastic inner liner202.

InFIGS. 15-16, the inner core200is metal. In some example embodiments ofFIGS. 15-16, the inner core is either a perforated or expanded metal liner204.

At opposite ends of the filter element20inFIGS. 13-16are end caps72,74. As with the other embodiments, the support structure80, depicted as inner core200, is secured to the second end cap74. In these embodiments, the inner core200is unsecured and free of the first end cap72. The inner core200is encapsulated and fixed within the second end cap74and extends less than a full extension of a length of the filter element20(between end caps72,74) to the first end cap72. In this embodiment, there is a space or gap78between a free end81of the inner core200and the first end cap72. The space or gap78is an open volume that is support structure-free. The inner core200is spaced a distance less than 50%, typically less than 25%, and often less than 10% from the first end cap72of the full extension between the first end cap72and second end cap74.

FIGS. 17-22depict another embodiment of filter element20. In this embodiment, the support structure80is unsecured to and is free of both the first end cap72and the second end cap74. As can be seen inFIGS. 20-22, the support structure80is spaced by space or gap78between free end81of the support structure80and the first end cap72; as well as a space or gap79between a free end83of the support structure80and the second end cap74.

FIGS. 24-44depict a variance in embodiments that incorporate a rail system300therein. The rail system300will act similar to a linear bearing, to provide linear support to the filter elements20and prevent axial twist and filter sway, but while allowing for movement of the pleated media50during pulsing to prevent damage to the element20, allow for pulse cleaning of the element20, and lead to longer element life.

In the embodiment ofFIGS. 24-28, the rail system300of the filter element20includes at least a first rail302. The first rail302is fixed to the first end cap72at/or adjacent to a first end303of the first rail302. The first rail302is positioned through the second end cap74. In many advantageous embodiments, the first rail302slidably extends through the second end cap74. The first rail302slidably extends through the second end cap74such that a second free end305of the first rail302is outside of the second end cap74at a position projecting away from a remaining portion of the filter element20.

Still in reference to the embodiment ofFIGS. 23-28, in some embodiments, the rail system300can also include a second rail304. The second rail304is spaced from the first rail302. The second rail304is fixed to the first end cap72at/or near a first end306and it slidably extends through the second end cap74. The second rail304has a second end307that is exterior of the second end cap74and is projecting or extending in a direction away from a remaining portion of the filter element20.

In the embodiment ofFIG. 23, it can be seen how the first rail302and second rail305are located exterior of the construction of pleated media50. In the embodiment shown inFIG. 23, first rail302and second rail304are on opposite portions of the filter element20. Specifically, in the racetrack shaped embodiment ofFIG. 23, the first rail302and second rail304are on opposite semi-circle ends of the element20. This can be seen inFIG. 25, in that the bottom end cap74is visible with first rail302projecting through the end cap74at the semi-circle end such that the end305of the rail302can be seen. The end307of the second rail304is visible projecting through the end cap74at the opposite semi-circle end.

FIG. 27shows a front view of each one of the rails302,304, each being identical in appearance. A top view of the rails302,304is shown inFIG. 28. In this embodiment, the rails302,304have a round cross-section.

When the element20ofFIGS. 23-28is pulse cleaned, the pleated media50expands as shown inFIG. 9, and the second end cap74is allowed to slide linearly along the first and second rails302,304. The element20ofFIG. 23further includes inner support structure80, shown in hidden lines inFIG. 23, and can be any of the previous embodiments of support structure80described above, and whose descriptions are not repeated herein.

In the embodiment ofFIGS. 29-34, the element20also includes the rail system300as depicted inFIGS. 23-28. The description is not repeated herein. In this embodiment, the rails302,304have a rectangular cross-section as shown inFIG. 34.

In the embodiment ofFIGS. 35-37, the filter element ofFIG. 11, in which the support structure80has first section82secured to the first end cap72and second section84secured to the second end cap74also includes first and second rails302,304, as described above. The filter element20inFIGS. 35-37is free of support structure in the support structure-free region86that is located axially between the first section82and second section84. The rails302,304are secured to the first end cap72, as described above, and extend through to be slidably within the second end cap74. The rails302,304can have a round, rectangular, or curved cross-section.

In the embodiment ofFIGS. 38-44, the filter element20also includes rail system300having first rail302and second rail304, as previously described. The element20, including the inner support structure80is also as earlier described. In this embodiment, the first and second rails302,304have a curved cross-section, as can be seen inFIG. 44.FIG. 42is a front view of the rails302,304, whileFIG. 43is a side view of the rails302,304in this embodiment.

The elements20are useable in a method of filtering. A dust collector, such as collector10, is provided. Dirty air will flow through the dirty air inlet14, into the dirty air plenum18, and then flow through at least one of the filter elements20. The filter elements20will filter or remove dirt and particulate from the air, when the air flows from the upstream side to the downstream side of the pleated media50. The clean filtered air will flow through a downstream side of the pleated media50, through the opening73of the open end cap72, and into the clean air plenum22, before exiting the dust collector10through the clean air outlet26.

The filter elements20will be periodically cleaned by emitting a pulse of compressed gas or air from the nozzles38and into the filter elements20by flowing through the open end cap72and into the filter interior54. The air pulse will then flow from the downstream side of the media50, through the media50, and to the upstream side of the media50. This will cause the pleated media50to expand, such as by bowing radially outwardly, and the overall element length to contract axially. After the pulse, the element20will return to its normal, filtering shape. The action of pulsing and allowing the element to change shape contributes to removing dust from the filter element and cleaning the element20, without damaging the element20.

The above represents example principles. Many embodiments can be made applying these principles.