Filter element with internal support and method

Abstract

A dust collector is provided having a filter element of pleated media having a porous support structure. [Solution] The dust collector 10 includes a housing 12 having an inlet 14 for taking in unfiltered or dirty air, as indicated by arrow 16, and the housing 12 defines a dirty air plenum 18 therein, which is also where a plurality of filter elements 20 are mounted, and the filter elements 20 are configured to remove particles (e.g., dust) from the air in the dirty air plenum 18.

Description

Technical Field

[0001] This application claims the benefit of priority of U.S. Provisional Patent Application No. 62 / 302,378, filed on March 2, 2016, which was filed as a PCT International Patent Application on February 20, 2017, and the entire disclosure of which is incorporated by reference in its entirety.

[0002] This disclosure relates to filter elements of pleated media having a porous support structure. This disclosure also relates to dust collectors using these filter elements and methods of pulse cleaning the filter elements.

Background Art

[0003] Filter elements of pleated media are often arranged in a tubular structure. The term "tubular" means a closed loop that can be circular, non-circular, oval, elliptical, racetrack-shaped, etc. The filter elements can be used in various applications such as cleaning the air intake of a compressor or filtering air in a dust collector. In many cases, the fluid to be filtered flows from the outside, through the pleats, and into the open inner volume of the tubular structure. In many situations, it is desirable to support the pleated media within the inner volume of the filter element to prevent the pleats from contacting themselves and collapsing within the inner volume. When the tubular structure is oval, elliptical, or racetrack-shaped, the problem associated with the pleats contacting themselves and collapsing is even greater than the problem caused by the shape of the cross-sectional shape of the media structure.

[0004] One typical approach for supporting the filter media inside the filter involves using an internal filter liner. The internal filter liner is often made of metal and is porous to allow the fluid to pass through. In the prior art, there was also the use of non-metallic inner liners.

[0005] When used in a dust collector, the filter element can be periodically cleaned by backflushing the element through the use of pulses of pressurized gas or air. The durability of the filter element is important for a long filter life. In prior art elements having an inner liner extending throughout the length between end caps, the pulse cleaning process can cause stress when the filter media attempts to flex outwardly. This can result in a failure point by tearing the media where it is connected to the end caps or causing damage to the end caps by the inner liner, leading to premature failure, leakage paths, or other problems. Summary of the Invention Problems to be Solved by the Invention

[0006] Improvements to the filter element and media support are desirable. Means for Solving the Problems

[0007] According to the principles of this disclosure, a filter element is provided. The filter element includes a structure of pleated filter media defining an internal volume. First and second opposing end caps are secured to opposing ends of the filter media. A support structure spans the filter media and is operably oriented within the internal volume. The support structure extends from a first set of inner surfaces to a second set of inner surfaces. The support structure is provided to extend less than the full extent between the first end cap and the second end cap.

[0008] One advantage of a support structure having at least one end that floats freely and is not attached to or separated from any other part of the filter element is that it allows the filter element to expand and contract axially. During pulse cleaning of the filter element, the element is allowed to deflect (expand) the media outwardly and then return to its original shape. This can be a dynamic, quick, snapping movement. This helps to clean the filter element by shaking dust off the media.

[0009] The support structure may include one of a pleated or extruded structure.

[0010] Each pleat of the support structure of the pleated structure may extend substantially parallel to the direction of the pleats of the filter media.

[0011] The pleated structure may include a semi-rigid pleated screen.

[0012] The support structure may be non-metallic.

[0013] The first end cap may be an open end cap that communicates with an internal volume.

[0014] The second end cap may be a closed end cap.

[0015] In one or more embodiments, the support structure is fixed to the second end cap.

[0016] In some arrangements, the support structure is not fixed to the first end cap and is free from the first end cap.

[0017] In some arrangements, the support structure may include a first section fixed to the first end cap, a second section fixed to the second end cap, and an element without a support structure in the region between the first section and the second section.

[0018] While the support structure is not fixed to the second end cap and is free from the second end cap, the support structure may be fixed to the first end cap.

[0019] The pleated media may be non-circular.

[0020] The pleated filter media may be in a racetrack shape having a pair of parallel sides joined by a pair of circular ends.

[0021] In one or more embodiments, the filter element is metal-free.

[0022] In some configurations, the filter element has no inner and outer liners.

[0023] In some configurations, the support structure includes a metal structure.

[0024] In some embodiments, the support structure includes an extruded structure.

[0025] In one or more configurations, the support structure is an extruded plastic inner liner.

[0026] The support structure may include an expanded metal structure.

[0027] The support structure may be realized as an inner liner.

[0028] The length of the filter element between the first end cap and the second end cap may be at least 2 inches.

[0029] The length of the filter element between the first end cap and the second end cap may be at least 20 inches and at most 100 inches.

[0030] 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 tube sheet separating the dirty air plenum from the clean air plenum. As characterized variously above, a plurality of filter elements are removably mounted in the tube sheet.

[0031] The dust collector may further include a cleaning system mounted to emit a pulse of gas from the downstream side to the upstream side and into the filter element to clean the filter element.

[0032] In another aspect, a method of filtration includes providing a dust collector as characterized above. There is a step of guiding a fluid to flow into an internal volume through a filter media. The fluid flows through a pleated filter media, and there is a step of supporting the filter media by using a support structure to prevent the filter media from collapsing together. The method includes periodically emitting a pulse of gas into the internal volume of the filter element and allowing the filter media to expand and contract axially.

[0033] Note that not all of the specific features described herein need to be incorporated in an arrangement in order for the arrangement to have some of the selected advantages according to the present disclosure.

Brief Description of the Drawings

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Mode for Carrying Out the Invention

[0035] A. Exemplary Dust Collector. FIG. 1 shows one exemplary application form in which a filter element constructed according to the principle of this disclosure can be used. The dust collector 10 includes a housing 12. The housing 12 has an inlet 14 for taking in unfiltered or dirty air as indicated by the arrow 16. The housing 12 defines a dirty air plenum 18 inside. The dirty air plenum 18 is also a place where a plurality of filter elements 20 constructed according to the principle of this disclosure are installed. The filter element 20 removes particles (such as dust) from the air in the dirty air plenum 18.

[0036] After passing through the filter element 20, the clean or filtered air flows into the clean air plenum 22. The clean air plenum 22 is also inside the housing 12. The clean air flows through the clean air outlet 26 as indicated by the arrow 24.

[0037] The tube sheet 28 divides the inside of the housing between the dirty air plenum 18 and the clean air plenum 22. The tube sheet 28 is typically made of sheet metal and has a plurality of holes or openings for holding the element 20 so that the filter element 20 can be removably installed in the tube sheet 28. To prevent the dirty air from bypassing the filter element and flowing into the clean air plenum 22 without being filtered by the filter element 20, the filter element 20 is removably sealed to the tube sheet 28.

[0038] The housing 12 may have an inclined wall 30 in the dirty air plenum 18 such that the particles and dust removed from the air fall by gravity and along the inclined wall 30. The base 32 may have a drum or other type of collector for removing dirt from the dirty air plenum 18.

[0039] The filter element 20 is periodically cleaned by discharging a pulse of gas, such as pressurized air, from the downstream side to the upstream side of the element 20. This is one way to backflush the filter element 20 and remove any dust or dirt that has accumulated on the upstream side of the filter element 20. In this embodiment, the cleaning system is indicated at 34. The cleaning system 34 includes a blowpipe 36 having a plurality of nozzles 38. In this embodiment, one nozzle 38 is shown for each filter element 20. However, in other embodiments, one nozzle per element is not necessarily required. The blowpipe 36 communicates with a pressurized air supply 40, which in turn communicates with a header pipe 42 and a pulse valve 44. Other embodiments are possible and this is merely an example.

[0040] During operation, dirty air flows through the dirty air inlet 14 into the dirty air plenum 18 and then through at least one of the filter elements 20. The filter elements 20 are to filter or remove dirt and particles from the air. The clean filtered air flows into the clean air plenum 22 through the downstream side of the elements 20 before exiting the dust collector 10 through the clean air outlet 26. The filter elements 20 are periodically cleaned by flowing a pulse of pressurized gas or air from the downstream side of the elements 20 into the upstream side of the elements 20 and discharging it into the filter elements 20 from the nozzles 38. When this is done, there is a pressure differential across each element 20 from the downstream side to the upstream side. In prior art systems, this pressure differential can cause the filter elements to malfunction by tearing at one or both of the end caps. The present filter element 20 is an improved form over the prior art in that it is configured to allow the filter media to expand outwardly or flex and axially contract along its length without failure along one of the end caps. Advantageous structures for the filter element 20 are further described below.

[0041] B. Improved Filter Element 20 Figures 2 - 11 are diagrams of exemplary embodiments of filter elements 20 that can be used in the dust collector 10. The filter element 20 includes the structure of a pleated media 50. The pleated media 50 can be a tubular shape 52 that defines an internal volume 54. The tubular shape 52 can be any shape that forms a closed loop, such as circular, non - circular, elliptical, oval, rectangular, ellipsoidal, or racetrack - shaped. In the embodiments shown in Figures 2 - 4, the filter element 20 is racetrack - shaped in that it has a pair of opposing parallel sides 56, 57 joined by its curved ends 58, 59. In the embodiments of Figures 13 - 16, the filter element 20 is cylindrical and the pleated media 50 is cylindrical with a substantially circular cross - section.

[0042] The pleated media 50 has a plurality of pleats 60. In FIG. 2, only some of the pleats 50 are shown for clarity. The pleats 60 have, in the illustrated embodiment, an outer pleat tip 61 and an inner pleat tip 62. The outer pleat tip 61 is along the outside of the pleated media 50. The inner pleat tip 62 is along the internal volume 54. When the pleated media 50 is of tubular shape, it has first and second opposing faces 64, 66 that generally correspond to the inner pleat tip 62.

[0043] The filter element 20 includes a first end cap 72. At the opposite end of the element 20 there is a second end cap 74. The first end cap 72 and the second end cap 74 are fixed to the opposing ends of the filter media 50.

[0044] In the example shown, the first end cap 72 is an open end cap having an opening 73 that communicates with the internal volume 54. The second end cap 74 can be either open or closed and in the illustrated embodiment it is a closed end cap.

[0045] The pleated media 50 can be fixed to the first and second end caps 72, 74, for example, by forming the ends of the pleated media 50 within the end caps 72, 74. In some examples, the first end cap 72 and the second end cap 74 are made of a non-metallic molding material. In some examples, the first and second end caps 72, 74 can be made of other types of materials and, for example, the media 50 can be fixed through the use of a potting material. The end caps 72, 74 are typically made of a urethane material.

[0046] The filter element 20 typically has a sealing structure or gasket to provide an airtight seal between the element 20 and any structure in which the element 20 is installed. For example, when used in the dust collector 10, there is usually a seal or gasket between the open end cap 72 and the tube sheet 28 to form a seal therebetween.

[0047] The filter element 20 further includes a support structure 80. The support structure 80 supports the pleated filter media 50. The term "support" generally means a structural mechanism for resisting opposing forces. The support structure 80 prevents the collapse of the pleats and the crushing through the interior of the filter element 20. By "collapse of the pleats", it means that the support structure 80 prevents the individual pleats from collapsing inwardly towards the interior volume 54 of the element 20 and the element 20 from crushing together through the interior.

[0048] The support structure 80 is operably oriented in the interior volume 54 of the pleated media 50. In many examples, the support structure 80 supports the pleated media 50. This can extend from the first opposing inner surface 64 to the second opposing inner surface 66 or span between the first opposing inner surface 64 and the second opposing inner surface 66. For example, the support structure 80 extends from the first opposing inner surface 64 to the second opposing inner surface 66 to structurally support the pleated media 50.

[0049] The support structure 80 is operably oriented in the interior volume 54 while at the same time functioning to structurally support or reinforce the pleated media 50. In the embodiments of FIGS. 2 - 12, the support structure 80 is not an inner liner for the pleated media 50. In the examples of FIGS. 2 - 12, the support structure 80 can structurally support the pleated media 50 in the absence of an inner liner or they can include a support - rigid inner liner. In some embodiments, the entire filter element 20 can be without an inner liner. In further exemplary embodiments, the filter element 20 has neither an outer liner nor an inner liner. However, in other embodiments, as can be seen in relation to the embodiments of FIGS. 13 - 16, the support structure 80 in these embodiments is the inner liner 200.

[0050] In one or more embodiments, the filter element 20 includes an inner screen 83 that lines the internal volume 54. The inner screen 83 can be realized in many forms including either a supportive and rigid inner liner to provide structural reinforcement for the element 20, or a non-supportive liner that does not structurally reinforce the element 20. In some embodiments, the inner screen 83 can be non-metallic, such as plastic, and can be porous to form an open lattice to allow air flow through. The screen 83 can extend between each of the first end cap 72 and the second end cap 74 and can be fixed to each of the first end cap 72 and the second end cap 74. Alternatively, the inner screen 83 can extend only partially between the first end cap 72 and the second cap 74. In some embodiments, the inner screen 83 is fixed to the second end cap 74 and extends along the inner pleat tip 62 for a portion of the length to the first end cap 72. In other embodiments, the inner screen 83 can be fixed to the first end cap 72 and can extend for a portion of the length to the second end cap 74. The inner screen 83 can include a perforated surface finish.

[0051] According to the principles of this disclosure, the support structure 80 extends for less than the full extent between the first end cap 72 and the second end cap 74. Preferably, the support structure 80 has at least one free-floating end that is not fixed or attached to the remainder of the filter element 20.

[0052] In a preferred arrangement, the support structure 80 is not joined to the inner pleat tip 62. That is, the support structure 80 is unattached or unjoined to the inner pleat tip 62. The outer pleat tip 61 is free to flex outwardly during pulse cleaning.

[0053] In the embodiments shown in FIGS. 6 - 8, the support structure 80 is fixed to the second end cap 74. In this embodiment, the support structure 80 is not fixed to the first end cap 72 and is free from the first end cap 72. As can be seen in FIGS. 6 - 8, the support structure 80 is enclosed and fixed within the second end cap 74 and extends less than the full extent of the length of the filter element 20 between the first and second end caps 72, 74 (between end caps 72, 74). As can be seen in FIG. 7, in this embodiment, there is a space or gap 78 between the free end 81 of the support structure 80 and the first end cap 72. The space or gap 78 is an open volume without the support structure. The support structure 80 is arranged at a distance of less than 50%, typically less than 25%, and often less than 10% from the first end cap 72 of the full extent between the first end cap 72 and the second end cap 74.

[0054] Many arrangements are possible. For example, in the arrangement of FIG. 10, the support structure 80 is fixed to the first end cap 72 and is not fixed to the second end cap 74 and is free from the second end cap 74. In FIG. 10, the support structure 80 extends for more than 50% and less than 99% of the total length between the first end cap 72 and the second end cap 74. For example, the support structure 80 can extend for 80% - 98% of the total length between the end cap 72 and the end cap 74.

[0055] In the embodiment of FIG. 11, the support structure 80 includes a first section 82 fixed to the first end cap 72 and a second section 84 fixed to the second end cap 74. The filter element 20 is free from the support structure in a region 86 without the support structure located axially between the first section 82 and the second section 84. In the example shown in FIG. 11, the region 86 is at the approximate center between the first end cap 72 and the second end cap 74. It is understood that the support - free region 86 can be located at any place along the length between the first end cap 72 and the second end cap 74. The region 86 has a length of less than 30%, typically less than 20%, and often less than 10% of the total length between the end caps 72 and 74.

[0056] The support structure 80 can be attached to one or more of the end caps 72, 74 in various ways. For example, the support structure 80 can be molded with the end caps 72, 74 joined thereto. The support structure 80 can also be potted to the end caps 72, 74 with a potting material. Other methods can also be used, including using adhesives, bonding agents, or other joining techniques.

[0057] There are many embodiments possible for the support structure 80. In the example shown in FIG. 5, the support structure 80 includes a pleated structure 90. The pleated structure 90 has at least a partial section with a plurality of pleats 92. The plurality of pleats 92 in the pleated structure 90 can extend in a direction parallel or non-parallel to the direction of the pleats 60 in the pleated filter media 50. Preferably, the pleats 92 extend in a direction parallel to the direction of the pleats 60 of the pleated filter media 50. In embodiments including the inner screen 83, the inner screen 83 prevents the pleated filter media 80 from interlocking with the pleats 92 of the support structure 80. In embodiments including a perforated surface finish or the inner screen 83, the pleated structure 90 can include a perforated surface finish 83 on its opposing side portions.

[0058] In other embodiments, the direction of the pleats 92 may be at a non-zero angle with respect to the direction of the pleats 60 of the pleated filter media 50. In one or more embodiments, the angle can be at least 45 degrees, often at least 70 degrees, for example an angle of 80 to 100 degrees.

[0059] The pleats 92 typically extend from a first inner surface 64 of the inner volume 54 of the pleated filter media 50 to a second inner surface 66.

[0060] The pleated structure 90 can be made from many types of materials. In a preferred structure, the pleated structure 90 includes a semi-rigid pleated screen 94. The pleated screen 94 can be made from plastic or reinforced cellulose. The pleated screen 94 has an open screen or mesh and allows fluid to flow therethrough. Preferably, the pleated structure 90 has a void volume of 60% or less.

[0061] The overall length of the filter element 20 between the first end cap 72 and the second end cap 74 is often at least 2 inches. In some embodiments, the length can exceed 50 inches. In many embodiments, the length of the filter element between the first end cap 72 and the second end cap 74 is at least 20 inches and 100 inches or less. The filter element 20 can be made from a non-metallic material such that it is metal-free.

[0062] The pleated structure 90 extends for less than the full extension between the first end cap 72 and the second end cap 74. As described above, this allows the opposite end 98 of the pleated structure 90 to float and there to be no connection to the opposite end cap or any other part of the filter element 20, while it can be implemented by fixing one end 96 of the pleated structure 90 to one of the end caps 72, 74. FIG. 11 also shows an embodiment that fixes the pleated structure 90 to both end caps 72, 74 but has a discontinuous region 86 that is free from the support structure 80.

[0063] One advantage of having a support structure 80 with at least one end freely floating and not attached to or separated from any other part of the filter element 20 is that it allows the filter element 20 to expand and axially contract. Refer to FIG. 9. During the pulse cleaning of the filter element 20 in the dust collector 10, the element 20 is allowed to deflect the media 50 outwardly (expand, refer to the dashed line 50 in FIG. 9), and then return to its original shape (refer to the solid line 50 in FIG. 9), which can be a dynamic, quick, slapping-like movement represented by the arrow 70. This helps to clean the filter element 20 by shaking the dust off the media 50. In prior art elements having an inner liner extending the entire length between the end caps, the pulse cleaning process causes stress when the filter media attempts to deflect outwardly, resulting in a failure point by tearing the media where it is connected to the end caps, leading to premature failure, leakage paths, or other problems. The filter element 20 avoids this problem because the support structure 80 has at least one free end that is separated, not attached, and freely floating within the element 20, allowing the element 20 to axially contract when the end caps 72, 74 move closer to each other and the media 50 deflects radially outwardly. The support structure 80 also prevents the collapse of the pleats.

[0064] Another embodiment of the support structure 80 is shown in FIG. 12. In the embodiment of FIG. 12, the support structure 80 is an extruded or injection molded structure. In the example shown in FIG. 12, the support structure 80 includes a plurality of cylinders 120. The cylinders 120 are fixed to each other by a plurality of cross braces 122. In the illustrated example, there are two cylinders 124, 125 arranged spaced apart from each other. The cylinders 124, 125 are porous and are shown as hollow cylinders, but can be of any shape. The cross braces 122 are shown perpendicular to the cylinders, but can be at various angles with respect to the cylinders 124, 125. The cylinders 124, 125 and the cross braces 122 can be made from plastic extrusion or by injection molding. The cross braces 122 are eight in number and are spaced apart from each other in the illustrated example, but can be more or less in number. With the opposing rails fixed to the opposing side portions of each of the posts 124, 125, each cross brace 122 is shown with a ladder-shaped cross section.

[0065] In the embodiments of FIGS. 13 - 16, alternative embodiments of the filter element 20 are shown. In these embodiments, the support structure 80 is an internal core or inner liner 200. FIGS. 13 - 16 show a cylindrical element 20 having a circular cross section. The pleated media 50 forms a cylinder and defines an open filter interior 54. Lining the filter interior 54 adjacent to the inner pleat tips 62 is the internal core 200. The internal core 200 is typically free and not attached to the inner pleat tips 62.

[0066] In FIGS. 13 - 14, the internal core 200 is non-metallic. In some examples, it is plastic. In the exemplary embodiments of FIGS. 13 - 14, the internal core 200 is an extruded plastic inner liner 202.

[0067] In FIGS. 15 - 16, the internal core 200 is metallic. In some exemplary embodiments of FIGS. 15 - 16, the internal core is either a perforated metal liner 204 or an expanded metal liner 204.

[0068] At the opposite ends of the filter element 20 in FIGS. 13-16, there are end caps 72, 74. Similar to other embodiments, the support structure 80 shown as the internal core 200 is fixed to the second end cap 74. In these embodiments, the internal core 200 is not fixed to the first end cap 72 and is free from the first end cap 72. The internal core 200 is enclosed and fixed within the second end cap 74 and extends less than the entire extension of the length of the filter element 20 up to the first end cap 72 (between the end caps 72, 74). In this embodiment, there is a space or gap 78 between the free end 81 of the internal core 200 and the first end cap 72. The space or gap 78 is an open volume without a support structure. The internal core 200 is arranged at a distance less than 50%, typically less than 25%, and often less than 10% from the first end cap 72 of the entire extension between the first end cap 72 and the second end cap 74.

[0069] FIGS. 17-22 show another embodiment of the filter element 20. In this embodiment, the support structure 80 is not fixed to either the first end cap 72 or the second end cap 74 and is free from both the first end cap 72 and the second end cap 74. As can be seen in FIGS. 20-22, the support structure 80 is spaced apart by a space or gap 79 between the free end 83 of the support structure 80 and the second end cap 74, as well as by a space or gap 78 between the free end 81 of the support structure 80 and the first end cap 72.

[0070] FIGS. 24-44 show the differences in an embodiment that includes a rail system 300 therein. The rail system 300 provides linear support to the filter element 20 and prevents axial twist and filter sway, while allowing movement of the pleated media 50 during a pulse to prevent damage to the element 20 and enabling pulse cleaning of the element 20. It acts like a linear bearing and results in a longer element life.

[0071] In the embodiments of FIGS. 24 - 28, the rail system 300 of the filter element 20 includes at least a first rail 302. The first rail 302 is fixed to the first end cap 72 at and / or adjacent to the first end 303 of the first rail 302. The first rail 302 is positioned through the second end cap 74. In many advantageous embodiments, the first rail 302 extends slidably through the second end cap 74. The first rail 302 extends slidably through the second end cap 74 such that the second free end 305 of the first rail 302 is outside the second end cap 74 in a position protruding away from the remainder of the filter element 20.

[0072] Still referring to the embodiments of FIGS. 23 - 28, in some embodiments, the rail system 300 may also include a second rail 304. The second rail 304 is spaced apart from the first rail 302. The second rail 304 is fixed to the first end cap 72 at and / or near the first end 306, and this extends slidably through the second end cap 74. The second rail 304 has a second end 307 that is outside the second end cap 74 and protrudes or extends away from the remainder of the filter element 20.

[0073] In the embodiment of FIG. 23, it can be seen how the first rail 302 and the second rail 305 are positioned outside the structure of the pleated media 50. In the embodiment shown in FIG. 23, the first rail 302 and the second rail 304 are in opposing portions of the filter element 20. Specifically, in the race - track - shaped embodiment of FIG. 23, the first rail 302 and the second rail 304 can be on the opposing semi - circular ends of the element 20. This can be seen in FIG. 25 in that the bottom end cap 74 is visible with the first rail 302 protruding through the end cap 74 at the semi - circular end such that the end 305 of the rail 302 is visible. The end 307 of the second rail 304 can be seen protruding through the end cap 74 at the opposing semi - circular end.

[0074] FIG. 27 shows a front view of one of each of the rails 302 and 304, each having the same appearance. The top views of the rails 302 and 304 are shown in FIG. 28. In this embodiment, the rails 302 and 304 have a circular cross-section.

[0075] When the element 20 in FIGS. 23-28 is pulse cleaned, the pleated media 50 expands as shown in FIG. 9, and the second end cap 74 is enabled to slide linearly along the first and second rails 302 and 304. The element 20 in FIG. 23 further includes an internal support structure 80 shown by hidden lines in FIG. 23, which may be any of the previous embodiments of the support structure 80 described above, and the description thereof is not repeated herein.

[0076] In the embodiments of FIGS. 29-34, the element 20 also includes a rail system 300 as shown in FIGS. 23-28. The description is not repeated herein. In this embodiment, the rails 302 and 304 have a rectangular cross-section as shown in FIG. 34.

[0077] In the embodiments of FIGS. 35-37, the filter element of FIG. 11 having a first section 82 fixed to the first end cap 72 and a second section 84 fixed to the second end cap 74 of the support structure 80 also includes the first and second rails 302 and 304 as described above. The filter element 20 in FIGS. 35-37 is free from the support structure in a region 86 without a support structure located axially between the first section 82 and the second section 84. The rails 302 and 304 are fixed to the first end cap 72 as described above and extend to be slidable within the second end cap 74. The rails 302 and 304 may have a circular, rectangular, or curved cross-section.

[0078] In the embodiments of FIGS. 38 - 44, the filter element 20 also includes a rail system 300 having the first rail 302 and the second rail 304 as described above. The element 20 including the internal support structure 80 is also as previously described. In this embodiment, the first and second rails 302, 304 have a curved cross - section as can be seen in FIG. 44. FIG. 42 is a front view of the rails 302, 304, and FIG. 43 is a side view of the rails 302, 304 in this embodiment.

[0079] C. Method The element 20 can be used in a filtration method. A dust collector, such as collector 10, is provided. The dirty air enters the dirty air plenum 18 through the dirty air inlet 14 and then flows through at least one of the filter elements 20. The filter element 20 filters or removes dirt and particles from the air as the air flows from the upstream side to the downstream side of the pleated media 50. The clean filtered air flows through the downstream side of the pleated media 50, through the opening 73 of the open end cap 72, and into the clean air plenum 22 before exiting the dust collector 10 through the clean air outlet 26.

[0080] The filter element 20 is periodically cleaned by flowing a pulse of pressurized gas or air into the filter interior 54 through the open end cap 72 and discharging it from the nozzle 38 into the filter element 20. The air pulse then flows from the downstream side of the media 50, through the media 50, to the upstream side of the media 50. This expands the pleated media 50, for example, by flexing it radially outward, and axially contracts the overall length of the element. After the pulse, the element 20 returns to its normal, filtering shape. The act of pulse - cleaning and allowing the element to change shape contributes to removing dust from the filter element and cleaning the element 20 without damaging the element 20.

[0081] The above represents exemplary principles. Many embodiments can be made by applying these principles.

Claims

1. A dust collector comprising: (a) a housing having a dirty air inlet, a dirty air plenum, a clean air outlet, a clean air plenum, and a tube sheet separating the dirty air plenum from the clean air plenum; (b) a plurality of filter elements removably mounted on the tube sheet, each filter element having a filter media and an internal volume; (c) a first closed end cap fixed to an end of the filter media and a second open end structure fixed to an opposite end of the filter media; (d) a support structure for supporting each filter element within the internal volume, (i) the support structure extending less than the full extent between the first closed end cap and the second open end structure and having at least one free end; (e) a cleaning system installed to emit gas pulses into the filter elements from the downstream side to the upstream side of the filter elements for cleaning the filter elements; wherein the support structure includes a plurality of cylinders connected together by a plurality of cross braces, the filter media of each filter element is unrestricted along an outer portion, thereby allowing the filter media to flex outwardly during pulse cleaning, a dust collector.

2. The dust collector according to claim 1, wherein the support structure is non-metallic.

3. The dust collector according to claim 1, wherein the filter media of each filter element is not coupled to the support structure.

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