HK1020265B - Fluted filter media - Google Patents

Description

Fluted filter media

Technical Field

The present invention relates to fluted filter media, and more particularly to fluted filter media having flutes that minimize the flow resistance of the filter.

Prior art of

Pleated filters that utilize filter media to remove impurities from fluids are well known and have a wide variety of configurations.

One problem common to all types of filters is that the filtering surface area is not large enough. Previous attempts to increase the filtration surface area for a given filter volume have not been very successful. Pleated filters are commonly used filters that employ pleated filter media to overcome the above-described deficiencies. Although pleated filter media can increase the filter area, flow is restricted because the pleats are positioned very close together so that more filter media can be positioned in a given volume, causing the pleats to be pressed tightly against each other. This resistance to flow may result in the necessity of increasing the flow rate through the filter media, thereby increasing the pressure differential across the filter, causing other problems within the system.

Most permeable filter media do not provide structural support and, as such, filters require a housing to support the filter material. This increases the manufacturing cost and increases the weight and size of the filter.

To improve flow resistance and provide a larger media area and filtration efficiency, a fluted filter construction may be employed. Fluted filtration media allows for increased media area per unit volume, with less flow resistance and substantially straight through flow.

While fluted filters can provide better flow characteristics and efficiency than prior art filter designs, fluted filters have the potential to achieve greater efficiency and better flow characteristics. The sealed upstream end of each channel will have a significant resistance to flow and more than half the cross-sectional area of the fluid flow will be blocked when combined with the filter material. Filter designs having larger cross-sectional areas transverse to the direction of fluid flow may provide improved flow and resistance characteristics.

It can be seen that there is a need for a new and improved filter having self-supporting, improved flow resistance, improved flow characteristics, and greater efficiency. In particular, fluted filters should have a leading edge that has less resistance and occupies a smaller cross-sectional flow area than standard fluted designs. In addition, the cross-sectional area of the filter media and the closed end of each flute at the upstream edge should be less than the open area at the upstream edge of each flute. Such an improved filter design should also be easy to manufacture without adding additional process steps. The present invention is directed to solving these and other problems associated with filter design.

Summary of The Invention

The present invention relates to fluted filtration devices, and in particular to fluted filtration media having improved flow characteristics.

According to a first embodiment of the invention, fluted filtration media comprises a fluted middle sheet between an upper and lower layer. It should be understood that the filter media can be rolled or stacked, requiring only a single sheet to be attached to a fluted sheet, as each layer can serve as either an upper or lower sheet of its adjacent layer. Further, the layers may be wound in a spiral configuration. Alternating ends of adjacent pockets formed by the fluted material are closed on either the upstream side or the downstream side. The first embodiment has a wedge-shaped groove that gradually widens from one end to the other end. The wedge-shaped slot cavity closed at the upstream end widens gradually towards the open downstream end thereof. Conversely, the wedge-shaped slot cavity, closed at the downstream end, widens gradually towards its open upstream end.

It will be appreciated that in this configuration, the area of the filter media perpendicular to the upstream flow direction comprises a large portion open to the chambers for receiving fluid. As the fluid is filtered through the various filter sheets, the filtered fluid flows through an enlarged downstream end. In this manner, the flow resistance of the filter can be greatly reduced compared to standard fluted filter material. Furthermore, the percentage of the upstream edge of the corrugated sealing edge material and the filter sheet is substantially less than the open area for receiving upstream fluid.

According to a second embodiment of the present invention, fluted filtration media includes asymmetric flutes having very sharp peaks and widened troughs. In this manner, the cross-sectional area of the upstream opening perpendicular to the flow direction at the edge of the filter media is greater than the cross-sectional area of the closed slot and the upstream edge of the filter material. Such a configuration may provide improved flow characteristics with greater filtration efficiency and reduced filter flow resistance.

According to a third embodiment of the present invention, fluted filtration media includes a flattened upstream edge that improves flow. According to this third embodiment, the leading edge of the filter media includes a corrugated sealing edge that blocks alternating flute chambers of the filter flute. The upstream edges of the corrugated beads and the fluted sheet are beveled to intercept fluid by a widening edge that is beveled toward the downstream end. When the fluid intersects the upstream edge, only the leading sheet edge is in contact with the upstream fluid, and both the corrugated bead and the fluted sheet are successively inclined. With this configuration, both the resistance and the proportion of the filter media that intercepts upstream fluid at the leading edge of the filter are reduced. Thus, improved flow, increased efficiency, and reduced filter flow resistance may be achieved.

These and other advantages and features of novelty which characterize the invention are pointed out with particularity in the claims annexed hereto and form a part hereof. However, for a better understanding of the invention, its advantages, and the objects obtained by its use, reference should be made to the drawings which form a further part hereof, and to the accompanying descriptive matter, in which there are illustrated and described preferred embodiments of the invention.

Brief description of the drawings

In the drawings, the same letters and reference numerals designate the same or corresponding parts.

FIG. 1 is a first illustration of a double-fluted filter media having wedge-shaped flutes according to the principles of the present invention

A perspective view of an embodiment;

FIGS. 2A-2B are schematic illustrations of a process for manufacturing the filter media of FIG. 1;

FIG. 3 is an end view of the filter media shown in FIG. 1;

FIG. 4 is an end view of one roll used to form the filter media of FIG. 1;

FIG. 5 is a detailed end view of the teeth for the roll shown in FIG. 4;

FIG. 6 is a perspective view of a second embodiment of a filter media having asymmetric flutes in accordance with the principles of the present invention;

FIG. 7 is an end view of the filter media of FIG. 6;

FIG. 8 is an end view of one roll used to form the filter media of FIG. 6;

fig. 9 is a perspective view of a third embodiment of a filter media having flattened leading flute edges in accordance with the principles of the present invention;

FIG. 10 is an end view of the filter media of FIG. 9;

FIG. 11 is a side cross-sectional view of the leading edge of the filter media of FIG. 9;

FIG. 12 is a graph of pressure differential across a filter versus air flow through the filter for various fluted filtration media designs;

FIG. 13 is a graph of pressure differential versus dust collection for various fluted filter media designs;

FIG. 14 is a cross-sectional view of a fourth embodiment of a filter media having upstream seal slots with a seal portion recessed inward from the upstream edge of the filter media in accordance with the principles of the present invention;

FIG. 15 illustrates a side schematic view of a method for forming the leading edge of the filter media shown in FIGS. 9-11;

FIG. 16 is a schematic side view of a sheet of filter media cut into strips using the method shown in FIG. 15;

detailed description of the preferred embodiments

Referring now to the drawings, and more particularly to FIG. 1, there is shown a portion of a layer of double-sided permeable fluted filter media, generally designated 100. The fluted filter media 100 of the first embodiment includes a plurality of wedge-shaped flute chambers 102. The pocket 102 is formed by a centrally located fluted sheet 108 that forms alternating peaks 104 and valleys 106 between facing sheets 110 (including a first facing sheet 112 and a second facing sheet 114). Troughs 106 and crests 104 divide troughs 102 into upper and lower rows. In the configuration shown in fig. 1, each upper row forms a slot cavity 122 closed at the downstream end, while the lower row forms a slot cavity 120 closed at the upstream end. The pocket 120 is closed by a first end bellows-seal 124 which completely fills the upstream end section of the pocket between the intermediate fluted sheet 108 and the second facing sheet 114. Similarly, the second end corrugated sealing edge 126 closes the downstream ends of the alternate spaced apart slot cavities 122. The peaks 104 and valleys 106 of the troughs 102 are bonded to the facing sheets 112 and 114 by an adhesive. The slot 102 and end sealing edges 124 and 126 may provide a filter element that is structurally self-supporting without a housing.

During filtration, unfiltered fluid enters the open upstream end cell 122, as indicated by the solid arrows. After entering the slot cavity 122, the unfiltered fluid is blocked by the second end corrugated sealing edge 126 at the downstream end. Thus, the fluid is forced through the fluted sheet 108 and the facing sheet 110. As the unfiltered fluid passes through the fluted sheet 108 or the facing sheet 110, the fluid will pass through the filter media layer to be filtered, as indicated by the hollow arrows. The fluid is then free to flow through the closed upstream end cell chamber 120 and out the open downstream end of the filter media 100. With the above arrangement, unfiltered fluid can be filtered through the fluted sheet 108, the upper facing sheet 112, or the lower facing sheet 114, and into the flutes 120, which are closed on the upstream side.

Referring now to fig. 2A-2B, there is shown a manufacturing process for fluted filter media that can be stacked or rolled into filter elements as described below. It should be understood that when the filter media is laminated or spiral pressed, adjacent layers are in contact with each other, with one face sheet 110 serving as both the top sheet for one fluted layer and the bottom sheet for the other fluted layer. It will therefore be appreciated that only one facing sheet 110 per fluted sheet 108 need be applied when laminating or rolling the layers.

As shown in fig. 2A, the first sheet of filter media 30 is fed between a pair of crimping rollers 44 forming a nip through a series of rollers, the rollers 44 having intermeshing corrugated surfaces to cause the first sheet 30 to become fluted as it enters between the rollers 44. As shown in fig. 2B, the first corrugated sheet 30 and the second flat sheet 32 of corrugated media are fed together into a second nip formed between one of the corrugating rollers 44 and an opposing roller 45. A sealant applicator 47 applies a strip of sealant 46 along the upper surface of the second sheet 32 prior to entering the corrugating roller 44 and the opposed nip roller 45. At the beginning of the rolling process, the first sheet 30 and the second sheet 32 may separate as the two sheets pass through the rollers 44 and 45. However, as the sealant 46 is applied, the sealant 46 forms the first end corrugation seal 38 between the fluted sheet 30 and the facing sheet 32. The peaks 26 and valleys 28 have corrugated sealing edges 42 applied at spaced intervals along their apexes or otherwise attached to the facing sheet 32 to form the slot cavities 34. The arrangement of sealing the facing sheet 32 to the fluted sheet 30 at one edge is a single faceable stackable filter media. If multiple layers are to be laminated or spiral pressed, a second corrugated sealing edge may be applied to the other edge of the fluted sheet 30. If lamination or spiral pressing of the layers is not required, a second corrugated sealing edge may be applied to the other edge and covered with a second facing sheet.

Referring back to fig. 1, it should be understood that each slot 102 is wedge-shaped. The closed upstream end slot cavity 120 widens gradually in the direction of the slot to an enlarged downstream opening, as shown in fig. 3. Similarly, as shown in FIG. 3, the slot cavity 122 has an enlarged upstream opening and tapers toward the closed end. In this manner, the portion of the filter media that is open to upstream fluid is significantly increased. In addition, as the fluid flows along the flutes and through the walls of the filter media (either the middle sheet 108 or the face sheets 112 or 114), the fluid will flow out an enlarged open end on the downstream side of the filter.

It should be appreciated that a special roller 144 is required to make the wedge groove 102 as shown in fig. 4. The roller 144 includes an outer peripheral surface having a plurality of aligned teeth 146 thereon. As can be seen more clearly in FIG. 5, the wedge-shaped teeth 146 widen progressively from a narrower first end toward a wider second end. It should be appreciated that the complementary teeth 147 on an opposing roller 145 vary from a narrower second end to a wider first end. Thus, as the intermediate sheet 108 passes through the nip between the complementary rolls 144, the filter media is pressed out of the flutes to form peaks 104 and valleys 106 that are alternately sloped along the length. It should be appreciated that the corrugated sealing edges 124 and 126 may provide a structurally self-supporting filter media.

The resulting filter media, as shown in fig. 3, includes wedge-shaped flutes 120 having a closed upstream end and flutes 122 having an open upstream end. It should be understood that in the case of a wedge-shaped slot 102, the slot cavity 122 has a larger cross-sectional area perpendicular to the flow direction than the slot cavity 120 with the upstream end closed. It should also be appreciated that the cross-sectional area of the pocket 120 perpendicular to the flow direction is greater than the cross-sectional area of the enclosed pocket 122 and the edges of the sheets 108, 112, 114. In this manner, the filter media 100 may filter a greater flow of fluid with less resistance. Since the chambers 120 and 122 taper in opposition to each other, the dimensions of the ends of the chambers at the downstream edge are reversed. In this configuration, it will be appreciated that at the closed downstream end of the filter media 100, the cross-sectional area of the flutes 122 is much smaller, while the cross-sectional area of the flutes 120 is much larger. Thus, fluid flows into the larger opening of the slot cavity 122 and out the enlarged and open downstream end of the slot cavity 120. In this configuration, fluid can flow through a filter material with much greater open space and less resistance, while still providing sufficient filter media area in the same volume.

Referring now to FIG. 6, which illustrates a second embodiment of the filter media of the present invention having asymmetric flutes, generally designated 200, the filter media 200 includes asymmetric flutes 202 that form relatively narrow peaks 204 and relatively wide arcuate valleys 206. The arc of the peak 204 has a smaller radius than the arc of the valley 206 of the asymmetric groove 202. The filter medium 200 includes a middle sheet 208 and a face sheet 210, the face sheet 210 including a first top face sheet 212 and a second bottom face sheet 214.

The facing sheet 210 is joined by an upstream corrugated sealing edge 224 and a downstream corrugated sealing edge 226. In this manner, sheets 208, 212, and 214 form a slot cavity 220 having a closed upstream end and a slot cavity 222 having a closed downstream end.

It should be appreciated that in the configuration shown in FIG. 6, the upstream portion of the filter media 200 that intercepts the fluid has an enlarged opening belonging to the sump chamber 222. In this manner, the slot cavity 222 can intercept the increased flow, which then passes through the sheets 208, 212, and 214, and through the slot cavity 220. In addition, the asymmetric trough filter media 200 may also provide a self-supporting filter structure.

Referring now to FIG. 7, the open end of the pocket 222 is much larger than the corrugated sealing edge 224 at the upstream end and the surface area perpendicular to the flow of the sheets 108, 212, and 214. This arrangement may reduce flow resistance at the filter inlet and may provide improved flow and dust collection performance.

Referring now to fig. 8, a roll for forming such an asymmetric fluted filter media 200 includes a plurality of teeth 246 disposed along its outer peripheral surface. The teeth 246 of the first roller 244 have a widened outer surface with narrow grooves formed between the teeth. The complementary roller should have narrow teeth and widened slots formed between the teeth to engage the teeth 246. It will be appreciated that asymmetrical peaks and troughs may be formed in the filter material as the rollers contact the filter material passing therebetween.

Referring now to fig. 9, there is shown a flattened filter media, generally designated 300, according to another embodiment of the present invention. This collapsed filter media includes a trough 302 having a collapsed upstream edge 316. Each groove includes a peak 304 and a valley 306 formed by a fluted center sheet 308. The facing sheets 310 sandwich the intermediate sheet 308 to form slot chambers 320 and 322. A first facing sheet 312 is in contact with the upper surface of the flutes and a lower facing sheet 314 is in contact with the lower surface of the flutes. Filter media 300 includes an upstream corrugated sealing edge 324 and a downstream corrugated sealing edge 326. The cross-sectional profile of each groove, as viewed from the downstream end, is shown in figure 10. The cross-sectional profile of each groove as seen from the upstream end is contrary to this, the open and closed portions being opposite to each other.

As shown in FIG. 11, the upstream side of the filter media 300 includes a flattened edge 316 along an upstream corrugated sealing edge 324. This forms a bevel 328 of the corrugated sealing edge 324 and the middle sheet 308 which is in contact with the flow of fluid. The inclined surface can achieve a larger flow rate and at the same time has a lower resistance, so that the flow resistance when passing through the filter medium can be reduced. It will be appreciated that the filter material and the corrugated sealing edge contacting the fluid at the edge 330 are smaller than the open area for intercepting the fluid, thus improving efficiency and flow.

Such a beveled edge can be formed in a variety of ways, but one preferred method is shown in fig. 15 and 16. As shown in fig. 15, an arcuate or circular forming member 350 is pressed against the upstream bellofram 324 before the seal material of the bellofram solidifies, thereby providing a means for quickly and easily forming an inclined surface 328. The forming tool 350 may be a ball rolled along the upstream corrugate strip or a circular member pressed onto the media 300. After the depressions are formed, the media 300 is cut at the upstream crimp strips 324 with a blade 360 or other cutting tool, as shown in FIG. 16, to form two strips of filter media 300 having a beveled upstream edge 330. It should be understood that multiple sets of widened and alternating corrugated sealing edges 324 and 326 may be applied to the sheet of media 300. When the sealing material of the corrugated sealing edges 324 and 326 solidifies, the sheet of filter media 300 is cut at the corrugated sealing edges 324 and 326 to form a plurality of sheets of filter media 300 having a flattened upstream edge.

Referring now to fig. 14, a fluted filter media 400 according to a fourth embodiment of the present invention is shown. The fluted filter media 400 is similar to other fluted filter media except that the fluted filter media 400 has a modified upstream edge and corrugation seal configuration, as will be described in detail below. As shown in fig. 14, the fluted filter media 400 includes flutes 402 having peaks and valleys with the upstream ends of the flute chambers 420 being closed and the downstream ends of the flute chambers 422 being closed. However, unlike other fluted filters having alternating flutes sealed at the upstream face of the electrode of the filter media, the flutes 420 include corrugated sealing beads 424 that are recessed inward from the upstream edge of the filter media 400 and seal the flutes. The slot cavity 422 has a corrugated sealing edge 426 at the downstream end.

It will be appreciated that the filter media 400 has the advantageous ability to accumulate larger particles 1000 on the upstream surface of the filter media. As shown in fig. 14, some of the slots 402 may become completely plugged if the particles 1000 are large enough. For prior art filter media, if several slots are plugged, the plug 1000 would have a greater effect due to its adjacent slot sealing on the upstream side, resulting in increased flow redirection around the plugged slot. However, as shown in fig. 14, when the pockets 420 are sealed at their upstream sides 424 and recessed inwardly from the upstream edges, a plug 1000 of an adjacent downstream closed pocket 422 may allow fluid to flow into the upstream end of the pocket 420 and through the fluted sheet or other filter material upstream of the seal 424. In this manner, fluid flows into the flute chambers 422 and is forced through the filter material back into the flute chambers 420, with the flute chambers 420 being open to the downstream side of the filter. This reduces clogging and provides better flow performance without pressure rise or other adverse effects on filter performance. In a preferred embodiment, the upstream sealing edge 424 is recessed from about 1/4 "to 1" from the upstream edge. In this manner, the fluted material is still capable of being self-supporting and reducing the effects of clogging at the upstream face of the filter media 400.

As shown in fig. 12, a comparison of fluted filter media having standard B-size flutes and wedge-fluted filter media 100 also having B-size flutes is made with the pressure drop of the air stream. In addition, a standard a size fluted filter media was compared to a flattened flute filter media 300 having a size flutes. It will be appreciated that in both cases the pressure differential across such a filter is reduced compared to a standard fluted filter arrangement having the same filter volume and nominal flute dimensions.

In addition, as shown in FIG. 13, the pressure drop in a standard B-slot is much higher than the pressure drop in a B-slot with a wedge-shaped filter media 100, after the filter media has collected dust. In addition, the initial pressure drop for the type a size flutes of filter media 300 having a flattened leading edge is significantly reduced as compared to the standard type a flutes.

It should be appreciated that the present invention provides a filter media having a large open area perpendicular to the direction of flow for intercepting fluid. This reduces the flow resistance and improves the efficiency.

It is to be understood, however, that even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and function of the invention, this disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the present invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.

Claims (11)

1. A filter structure comprising:

(a) filter media comprising at least one fluted filter media sheet having an upstream edge and a downstream edge;

(i) the fluted filter media sheet comprises a plurality of alternating circular peaks and circular valleys forming:

(A) a first set of spaced flutes on one side of the fluted filter media sheet; each slot of the first set of slots has a longitudinal extension direction extending generally between an upstream edge and a downstream edge of the sheet; and

(B) a second set of spaced flutes on a second side of the fluted filter media sheet; each slot of the second set of slots has a longitudinal extension direction extending generally between the upstream edge and the downstream edge of the sheet;

(ii) a width of each slot of the first set of slots tapers along the longitudinal extension direction from a location proximate the upstream edge to a location proximate the downstream edge; and

(iii) the width of each slot of the second set of slots tapers along the longitudinal extension from a location proximate the downstream edge to a location proximate the upstream edge; and

(b) the at least one fluted filter media sheet is comprised of media that is fluted by passing between a pair of fluted rollers having a plurality of wedge-shaped teeth; the direction of the inclination of the teeth of a first of the pair of grooved rollers is opposite to the direction of the inclination of the teeth of a second of the pair of grooved rollers;

(c) at least one non-fluted filtration media adjacent to the at least one fluted filtration media sheet; and

(d) securing the at least one sheet of non-fluted filter media to the first corrugated sealing edge of the at least one sheet of fluted filter media.

2. The filtration structure of claim 1, wherein: the filter element includes at least one fluted filter media sheet secured to at least one non-fluted media and wound into a coiled configuration.

3. The filtration structure of claim 1, wherein:

each flute of said first set of flutes being closed at a location proximate to a downstream edge thereof relative to unfiltered material flowing therefrom; and

each flute of the second set of flutes being closed at a location adjacent an upstream edge thereof relative to unfiltered material to flow therein.

4. A filter structure according to claim 3, wherein:

each groove of said first set of grooves is sealed by said first corrugated sealing bead proximate its downstream edge location; and

each groove of the second set of grooves is sealed by a second corrugated sealing edge located adjacent the upstream edge.

5. The filtration structure of claim 1, wherein: each flute of the second set of flutes is collapsed to close proximate a selected edge of the filter media.

6. The filtration structure of claim 5, wherein: the selected edge is the upstream edge.

7. The filtration structure of claim 1, wherein:

(a) the filter media comprises a stack of fluted sheets, each sheet being positioned between two flat sheets of media;

(i) each fluted sheet in the stack of fluted sheets comprises alternating peaks and valleys forming:

(A) a first set of flutes disposed on one side of the fluted filter media; and

(B) a second set of flutes disposed on a second side of the fluted filter media;

(ii) the width of each slot of the first set of slots tapers along a longitudinal extension from a location proximate the upstream edge to a location proximate the downstream edge; and

(iii) the width of each slot of the second set of slots tapers along a longitudinal extension from a location proximate the downstream edge to a location proximate the upstream edge.

8. The filtration structure of claim 7, wherein:

each flute of said first set of flutes being closed at a location proximate to a downstream edge thereof relative to unfiltered material flowing therefrom; and

each flute of the second set of flutes being closed at a location adjacent an upstream edge thereof relative to unfiltered material to flow therein.

9. The filtration structure of claim 7, wherein:

each groove of said first set of grooves is sealed by said first corrugated sealing bead proximate its downstream edge location; and

each groove of the second set of grooves is sealed by a second corrugated sealing edge located adjacent the upstream edge.

10. The filtration structure of claim 7, wherein: each flute of the second set of flutes is collapsed to close proximate a selected edge of the filter media.

11. The filter structure according to claim 10, wherein said selected edge is said upstream edge.