CZ20004222A3 - Filter assembly and ways to maintain it - Google Patents

Abstract

An air purifier (20) arrangement for purifying air in ablative thermal imaging processes includes a housing (45) and a removable and replaceable element assembly (50). The housing (45) has an interior space, an inlet conduit (24) and an outlet conduit (28). The element assembly (50) includes first and second filter elements (52, 54) that are axially aligned with each other and secured together in a stackable configuration. The first filter element (52) is filled with a medium for filtering particulate matter. The second filter element (54) is filled with a medium for filtering non-toxic gases, such as formaldehyde. In operation, the exhaust fan assembly (16) directs air flow through the inlet duct (24) into the interior of the first filter element (52), then through the means filling the first filter element (52), then through the means filling the second filter element (54) into the interior of the second filter element (54), and finally to the outside environment via the outlet duct (28) that passes through the housing (45).

Description

Technical area

This invention relates to a filter arrangement and methods of maintaining the same, particularly a filter for removing particles and gases generated during ablative thermal imaging methods.

State of the art

In some types of printing processes, the image is captured on film using photographic technology. Chemical solutions are applied to the film to develop and burn the image onto a plate. The plate is then used in a printing press. This type of printing process is increasingly being replaced by computer-to-plate (CTP) technology.

In CTP technology, the image is captured digitally. The digital image is transferred to a laser, which then acts on the film. The film typically consists of a layer of dye that is laminated to a plastic sheet. Such films are commercially available from companies such as Kodak and DuPont. The laser burns or removes (ablates) the dye coating, creating the image. The film with the image is then exposed and printed on a plate. The plate is then used in a printing press. This process is known as ablative thermal imaging.

When the laser burns the dye coating on the film, certain gases and contaminants or particles are produced. These gases may include, for example, formaldehyde, or odors such as sulfur. It is desirable that the air in the vicinity of the CTP technology is purified.

The essence of the invention

The present invention provides a filter arrangement comprising an assembly of first and second means. The assemblies of first and second means are preferably stacked in an axially coaxial arrangement. The assembly of the first means preferably removes particles from an air stream. The assembly of the second means preferably

removes odors or gases from the air stream. Preferably, the second means assembly is positioned downstream of the first means assembly. The first means assembly preferably has first and second covers at its opposite ends, between which is an internal open space of the filter. The first end cover preferably has an air flow opening that opens into the open internal space of the filter, while the second end cover is closed to the air flow. The second means assembly preferably has first and second covers at its opposite ends and defines an internal open space of the filter. Preferably, the first end cover of the second means assembly is closed to the air flow and abuts the second end cover of the first means assembly. Furthermore, the second end cover of the second means assembly is preferably provided with an air flow opening towards the open internal space of the filter of the second means assembly.

In one of its preferred embodiments, the air flow to be filtered is directed into the open interior of the filter assembly of the second means, and subsequently passes out through an opening in the second end cap of the second means assembly.

In certain preferred embodiments of the present invention, the filter arrangement is oriented within the housing. Preferably, a sealing system is used to create an airtight seal between the filter and the housing. Such sealing systems may include axial sealing systems or radial sealing systems.

Methods of filtration and replacement of the filter assembly are also provided by the present invention. Preferred methods may utilize certain preferred arrangements as described below.

Overview of images in drawings

Figure 1 is a schematic illustration of one embodiment of an air purification system constructed in accordance with the principles of the present invention.

Figure 2 is an axonometric view of one embodiment of an air purifier constructed in accordance with the principles of the present invention.

Figure 3 shows a cross-section of the air purifier of Figure 2, showing the assembly of elements arranged and oriented therein.

Figure 4 is an axonometric view of one embodiment of an assembly of elements usable in the air purifier shown in Figure 2 , in accordance with the principles of the present invention.

Figure 5 is a cross-sectional view of the assembly of elements of Figure 4 , showing a first filter element stackably arranged and adjacent to a second filter element.

Figure 6 is a bottom view of the assembly of elements shown in Figures 4 and 5 , showing the outlet conduit and sealing member, in accordance with the principles of the present invention.

Figure 7 is a side elevational view of the air purifier shown in Figure 2 and schematically illustrating differential pressure switches in accordance with the principles of the present invention.

Figure 8 is a bottom view of the air purifier shown in Figure 7 , showing a mounting structure, according to the principles of the present invention.

Figure 9 is a partial, enlarged cross-section of a second filter element shown in Figure 5 in accordance with the principles of the present invention.

Figure 10 shows a cross-section of an alternative embodiment of an air cleaner, analogous to the view of Figure 3, and showing a radial sealing system.

Figure 11 is a partial cross-section showing the end cover sealing profile for a radial sealing system used in the arrangement of Figure 10.

Examples of embodiments of the invention

I. Some problems with known existing arrangements

In connection with ablative thermal imaging techniques, filtration systems have been used in the past. These systems typically included an element that was open at both ends and included a particulate filter radially arranged within a carbon filter. The filter element was attached to the housing or cover by means of a central yoke and wing nut. Air was directed into the housing inlet, into the interior of the particulate filter, through the carbon filter media, and then out of the housing through an outlet duct. The outlet was typically located on the side of the housing. There was no way to determine if the filter element needed to be replaced, or if the filter was even installed in the housing assembly.

This arrangement presented problems. For example, the relative orientation of the air outlet on the side of the housing sometimes caused uneven airflow through the filter.

Furthermore, replacing the filter required unscrewing the wing nut and cover. The wing nut was a loose component that could easily fall inside the filter housing or be lost during filter replacement.

Furthermore, the radial orientation of the particulate filter, considered from the point of view of the air flow, in front of the carbon filter, has in some cases led to problems with clogging. For example, once the particulate filter has become clogged, the resulting airflow through the carbon filter arranged behind it has subsequently changed and become less uniform. In other words, the carbon filter located immediately behind the clogged part of the particulate filter will not have as much air flowing through it. The air flow will therefore be diverted towards other parts of the carbon filter and these will wear out more than the areas of the carbon filter that are immediately adjacent to the clogged parts of the particulate filter.

Furthermore, because the filter element had holes at both ends, it was difficult to replace it or perform system repairs and maintenance. When replacing • · ··· · • · · ·

accumulated particles could fall out through holes in the housing or other unwanted locations.

The arrangements and methods described below help to solve these and other problems.

II. Arrangement according to figures 1 to 10

A. Basic system layout

Referring to the accompanying Figure 1, reference numeral 10 schematically indicates an air purifier system. In Figure 1, reference numeral 12 generally indicates a process that produces particles and non-toxic gases as by-products. Process 12 may be formed, for example, by an ablative thermal imaging method. Such processes typically produce particles having a size of the order of 0.1 microns and larger and may include sulfur, silica, carbon, aluminum, phosphorus, and/or zinc, depending on the film used. These processes may also produce gases such as formaldehyde in amounts of 0.5 to 7.5 parts per million at room temperature, depending on the flow rate. As the flow rate decreases, the concentration of gases such as formaldehyde increases.

Typically, the structure is oriented near the process 12 to direct air near the process to the air cleaner 20. This may be accomplished by a vent or nozzle 14 near the process 12. The exhaust fan 16 creates a vacuum in the air cleaner 20 and then into the area of the nozzle 14 to draw particles, fumes, and smoke into the air cleaner 20. The particles, fumes, and smoke are then drawn into a conduit, such as a flexible hose 22, by the vacuum. The hose 22 is in fluid communication (i.e., air flow communication) with an inlet conduit 24. The hose 22 and the inlet conduit 24 may be sealed together by any suitable means, such as a hose clamp 26.

From the inlet duct 24, air containing particulates and non-toxic gases is directed to the air cleaner 20. The air cleaner 20 removes at least about ninety percent, and typically at least ninety-five percent, of all particulates having a size greater than 0.5 microns, and further removes at least ninety percent, and typically at least ...

98.7% of the formaldehyde in the gaseous phase from the air. The purified air then passes through the outlet pipe 28, where it is then optionally fed to the exhaust fan 16 and then blown into the surrounding environment. A hose 30 can typically be used to connect the outlet pipe 28 to the exhaust fan 16. Again, a hose clamp 32 can be used to ensure a secure seal between the outlet pipe 28 and the hose 30.

In the attached figure 2, the air cleaner 20 is shown in axonometric view. Generally speaking, the air cleaner 20 comprises a housing 45, with a body 46 and a removable cover 47. It can be seen that the inlet pipe 24 passes through the cover 47.

Attention is now directed to Figure 3. Figure 3 shows a cross-section of air cleaner 20. As can be seen in Figure 3, air cleaner 20 includes a housing 45 in which an assembly of elements 50 is disposed. Preferably, the assembly of elements 50 includes a first element 52 secured in axial alignment and stackably disposed on top of a second element 54. It will be noted that inlet conduit 24 is shown extending through cover 57 and opening into an interior open filter space 56 of first element 52. It will also be noted that outlet conduit 28 is shown extending from body 46 and in air flow communication with the open interior of filter 58 of second element 54.

Generally speaking, during operation of the air purifier 20, air containing particulates and non-toxic gases is preferably drawn through the inlet duct 24 into the interior open space of the filter 56 of the first element 52, through the means 60 of the first element 52, and into the channel 62 between the housing 45 and the element assembly 50. The first element 52 preferably operates to remove particulates from the air stream. From the channel 62, the air stream is preferably directed through the means 64 of the second element 54, and into the open interior of the filter 58. The means 64 of the second element 54 preferably operates to remove non-toxic gases, such as formaldehyde, from the air stream. From the open interior of the filter 58, the purified air flows through the outlet duct 28 and optionally through the exhaust fan 16 to the ambient environment.

• · ··· · • · · · • · · > ··

B. Assembly of 50 elements.

Attention is now directed to the accompanying Figure 4. In Figure 4, one of the preferred element assemblies 50 is shown in axonometric view. As can be seen, the element assembly 50 includes a cylindrical arrangement comprising a first element 52 in axial alignment and stackably disposed on a second element 54. The element assembly 50 is removable and replaceable within a housing 45. As shown in Figure 4, the element assembly 50 preferably includes a handle 75 operatively attached thereto. The handle 75 assists in the removal and orientation of the element assembly 50 relative to the housing 45.

The first and second filter elements 52,54 are secured to each other and stacked in axial alignment. By stacked in axial alignment is meant that the first and second filter elements 52,54 are axially aligned, preferably sharing a common centerline 78 (see Figure 5), but are not radially aligned with each other.

On the contrary, they are stacked, that is, one of them rests on top of the other one in a vertical orientation, as shown in Figures 4 and 5.

The term removable and replaceable means that the element assembly 50 can be removed from the housing 45 without destroying the housing 45. The element assembly 50 can then be replaced with a new, unused element assembly that is oriented within the housing 45 so as to be functional. The old, original element assembly 50 can then be disposed of or recycled, as desired.

In a preferred embodiment, as illustrated, the assembly 50 of elements includes a first element 52 that is secured and stacked on a second element 54. Preferably, the first and second elements 52,54 are secured to each other by spot welding the end caps of the elements together. That is, the second end cap 96 (see the accompanying Figure 5) of the first element 52 is spot welded to the first end cap 120 (see the accompanying Figure 5) of the second element 54.

Attention is now directed to Figure 5. In Figure 5, an assembly of elements 50 is shown in cross-section. Preferably, the first element 52 is cylindrical in shape and includes inner and outer inserts 90, 91 for supporting the filter medium 60. The inner and outer

«« • • « ·««« • « * • «« ♦ • • • · • • · « • • * • • • « · • • • · • • • • • • • · * · • · « * · • · * · ·

The inserts 90,91 may comprise a variety of materials suitable for forming a rigid support structure. Examples include metal inserts, perforated metal inserts, and plastic inserts. In general, the inner and outer inserts 90,91 should preferably be selected from materials that are suitably perforated or otherwise porous so as not to substantially impede air flow through the arrangement, and that have suitable structural strength and stiffness for the construction of the device, thereby providing the arrangement with sufficient axial strength for its intended use and protecting the structure of the device from damage. Typical inserts have an open area of at least fifty percent, but often sixty percent or more. Typically, arrangements with galvanized metal or plastic inserts are considered to be preferred.

Preferably, first and second opposing end caps 95,96 are disposed at opposite ends of the filter element 52. In the preferred embodiment shown, the means 60, the inner liner 90, and the outer liner 94 are located between and secured to the end caps 95,96. Particularly preferred embodiments shown utilize end caps 95,96 made of a metallic material, with the means 60 and the liners 90,91 secured to the end caps 95,96 using, for example, polyurethane or epoxy resin.

Still referring to the attached Figure 5, it should be noted that the second end cap 96 is formed as a closed end cap. That is, the end cap 96 does not have any air flow openings therein, so that generally speaking, air is prevented from flowing through the end 97 from the interior open space of the filter 56 into the channel 62 (see Figure 3).

In contrast, the first end cap 95 is formed by an open end cap having a central opening 100 therein. In use, the first filter element 52 is secured within the air cleaner 20 by the opening 100 defining the inlet duct 24 (see the accompanying Figure 2). Due to the appropriate sealing (by a variety of methods) of structures such as the structure illustrated in Figures 3 and 4, the airflow is prevented from entering the duct 62 without first being filtered by passage through the means 60.

·· ··«· ·· * , ;· · «·»· **·· ··· ··· «·· • · ···» ·«·· · ··· ··· ·· · « · ·· · · · »«· · ·· ·

For the arrangement shown in the attached Figure 4, the sealing system preferably comprises an axial sealing system. For example, the sealing member 106 is formed by an O-ring 107 which is positioned on the first end cap 95 and defines the opening 100. The O-ring 107 is compressed within the housing 45, preferably by means of the cover 47, thus forming a seal 110 therebetween (see Figure 3). Many different materials can be used for the O-ring 107, preferably neoprene EPDM SBR in the form of a sponge rubber. This material is described in more detail below. Furthermore, as shown in the attached Figure 3, a seal 108 can be secured or attached to the inlet pipe 24 and the first end cap 95. However, it should be remembered that the axial sealing system of the sealing member 106 is the main sealing system on which the preferred embodiments are based.

In alternative embodiments, a radial seal may be used between the inlet pipe 24 and the opening 100. One suitable radial seal arrangement is described in more detail in European Patent No. 0 329 659 B1, which is incorporated herein by reference. One exemplary embodiment of a radial seal arrangement is shown in Figure 10. This embodiment is discussed below in connection with Figure 10.

Preferably, the first filter element 52 operates as a particulate filter, that is, the first element 52 removes particulates such as sulfur, silica, carbon, aluminum, phosphorus, and/or zinc to improve the quality of the imaged film or plate in process 12 (see attached Figure 1). The means 60 is preferably formed of a pleated means, although other alternatives are contemplated. A description of an example of a preferred material for the means 60 is described below.

As air passes through the inlet conduit 24 and flows into the interior 56 of the filter, carrying with it particles and non-toxic gases, it passes through the means 60. Preferably, the means 60 removes particles having a size greater than about 0.5 microns. It is to be understood that once particles and contaminants are collected and deposited, they remain within the interior open space 56 of the filter. This aids in their easy and clean removal when the element assembly 50 is replaced. Since the end cap 96 is formed by a closed end cap, the collected particulate matter remains within the interior space 56 of the element 52 during replacement.

Still referring to the accompanying Figure 5, the second filter element 54 is shown preferably in axial alignment with the first element 52 which is stackably arranged below it. As can be seen in Figure 5, the second element 54 is preferably cylindrical in shape having an outer diameter equal to the outer diameter of the cylindrical first filter element 52. The second filter element 54 preferably has an axial length significantly shorter than the axial length of the first filter element 52. It is for this reason that in preferred arrangements the size of the means 64 required for absorbing non-toxic odors and gases is not as large as the means 60 required for removing particles. The second filter element 54 is preferably oriented downstream (in terms of airflow) of the first filter element 52. In this manner, after the air has passed through means 60 and the particulates have been removed, the air then passes through means 64 in the second filter element 54 to remove non-toxic gases, such as formaldehyde.

The second filter element 54 preferably includes a cylindrical inner liner 112 and a cylindrical outer liner 113 for supporting the means 64. Preferably, the means 64, the inner liner 112 and the outer liner 113 extend between the first and second end caps 120, 121. The lining of the inner liner 112 in preferred systems is formed by an inner liner 114 with a bulking agent. Similarly, the lining of the outer liner 113 is formed by an outer liner 115 with a bulking agent. The bulking agent liners 114 and 115 preferably extend between the first and second end caps 120, 121. The inner and outer bulking or receiving liners 114, 115 preferably function to help retain or contain the means 64, such as particulate carbon and carbon dust, within the assembly. In other words, the inserts 114 and 115 facilitate the passage of the agent 64 through the inserts 112, 113 either into the interior 58 of the filter or out of the element assembly 50. The agent-receiving inserts 114, 115 are preferably made of electrostatic felt. One of the materials that can be used is described in detail below.

The first end cap 120 is preferably formed as a closed end cap. That is, the first end cap 120 does not have any openings therein for the passage of air, so that generally speaking, air cannot pass through said first end cap 120 into the internal volume 58. In contrast, the second end cap 120 is

the end cap 121 preferably formed as an open-ended cap having a central opening 125 therein (see attached Figure 6).

The second element 54 preferably operates to non-toxically remove gases or odors from the air. The means 64 is selected depending on the types of gases or odors to be removed from the air. Preferably, the second element 54 serves as an absorbent or adsorbent. As used herein, the terms absorbent and adsorbent should be considered to mean the same thing. Typically, the second element 54 will be comprised of a chemical absorbent. In certain preferred systems, the second element 54 will be comprised of a particulate chemical absorbent means. While a number of different means designs may be used and are contemplated herein, in preferred embodiments, the means 64 comprises activated carbon. Further description of an example of a preferred means 64 is provided below.

Preferably, the first and second end caps 120, 121 are formed of metal, such as 18 gauge galvanized steel, with the inserts 112, 113 and the means 64 attached thereto, for example, using polyurethane or epoxy.

In certain preferred embodiments, an arrangement is provided for retaining and filling the means 64. In other words, if the means 64 is selected to be a granular or loose particulate chemical absorbent, such as activated carbon, then the described arrangement provides one example of a preferred system for ensuring that the loose particulate means 64 remains in a filled, sealed condition. Attention is now directed to Figure 9. Figure 9 shows a partial enlarged cross-section of the second element 54. Figure 9 shows one preferred embodiment of the filling, which is generally indicated by the reference numeral 140. In this illustrated example, the filling structure 140 includes a plate or lid 141 and a compressible sealing member 142. The lid 141 is preferably formed by a cylindrical disk 144 formed of a non-porous, rigid material, such as plastic. Preferably, the sealing member 142 is formed of a soft, compressible material having the same cylindrical shape as the second element 54. One useful material for the sealing member 142 is rubber, such as neoprene, which is described in more detail below.

·· ·· · · · · · · · · ·

Still referring to the accompanying Figure 9, note that the inner liners 112 and 114 are preferably folded or bent or crimped over the lid 141 in its region 145. Analogously, note that the outer liners 113,115 are folded or bent or crimped over the lid 141 in its region 146. The crimped or bent portions 145,146 are then secured between the first end cap 120 and the lid 141.

For assembly of the second element 54, the second end cap 121 is preferably attached to the inner liners 112,114 and the outer liners 113,115 with epoxy or a suitable adhesive. Furthermore, a means 64, for example formed of carbon particles, is preferably filled between the inner liners 112,114 and the outer liners 113,115. A compressible sealing member 142 is placed on the upper side of the means 64. A plate or cap 141 is placed on the upper side of the compressible sealing member 142. Furthermore, the inner liners 112,114 are preferably pressed over the cap 141 to form a region 145. The outer liners 113,115 are preferably pressed or bent over the cap 141 to form a region 146.

It should be understood that the compressible sealing member 142 operates to provide a tight seal to the device 64. For example, if activated carbon is used as the device 64, the device 64 may collapse after a period of time after initial assembly. As the particulate carbon collapses, the sealing member 142 expands, which in turn fills any free space between the device 64 and the cap 141.

In use, the second element 54 is secured within the air cleaner 20 by an opening 125 (see the accompanying Figure 6) which surrounds the outlet duct 28 (Figure 3).

As a result of using a suitable seal, which can be implemented in many different ways, for structures such as the one shown in the attached figures, the air flow is prevented from entering the opening 125 without being filtered by the means 64.

Attention is now directed to the accompanying Figure 6. Figure 6 shows a bottom view of the assembly of elements 50. Specifically, there is shown a bottom view of the second element 54, which is shown to include an axial sealing system. The axial sealing system includes a sealing member 130 that surrounds or circumscribes the outlet opening 125. Preferably, the sealing member 130 is formed by a soft, compressible O-ring 132. Once the assembly of elements 50 is mounted within the housing 45 and the cover 47 is secured in place by means of the clamps 32 (Figure 3) to provide axial pressure, the sealing member 130 forms a seal 136 (Figure 3) between the wall of the housing 45 and the second element 54.

It can then be seen that the preferred embodiment of the illustrated element assembly 50 comprises first and second elements 52, 54 which flow in opposite directions with respect to each other. For example, the first element 52 operates so that the air flow therein is directed from the inside to the outside, a so-called reverse flow system, as shown by arrows 147 in Figure 3. This is in contrast to the second element 54 where the air flow is from the outside of the element 54 to the inside 58, a so-called forward flow system, as shown by arrows 148 in the accompanying Figure 3. All of this helps to ensure a more uniform filling. For example, if certain parts of the first element 52 begin to fill or become occluded, no particular parts of the second element 54 are affected in filling.

Attention now turns to the accompanying Figure 10. In Figure 10, a first element 200 is shown, which is a modification of the first element 52 shown in the accompanying Figures 3-5. The first element 200 does not include a sealing member of the type used to provide an axial seal, such as the sealing member 106. The first element 200 includes a ring adapter structure 202. The ring adapter structure 202 is oriented between the inner liner 204 and the inlet conduit 218. One useful ring adapter structure is described, for example, in U.S. Patent Application Serial No. 09/025,828, filed February 19, 1998, which is incorporated herein by reference. Generally speaking, the ring adapter structure 202 includes a circular member with lugs 222 that engage the inner liner 204; further includes an inner beveled surface portion 224 and a necked or end portion 206. As can be seen from the accompanying Figure 10, the beveled surface 224 extends between the feet 222 and the end portion 206. The end portion 206 may be generally formed by a cylindrical member having a circular cross-section that defines an inner radial surface 225.

Still referring to the accompanying Figure 10, the first element 200 has a first end cap 210. As was the case with the first end cap 95 in the embodiment

3, the first end cap 210 defines an opening 212 for air flow through the component. In contrast to the first end cap 95, the first end cap 210 in the accompanying FIG. 10 is constructed of a soft, compressible material such that the sealing portion 215 is compressed between and against the air flow inlet duct 218 and the end portion 206 of the annular structure 202. One useful material for the first end cap 210 is a compressible, polymeric material, such as polyurethane, and more specifically, foamed polyurethane. One useful material is described in U.S. Patent No. 5,669,949 for an end cap 3, which is incorporated herein by reference. As can be seen in the accompanying FIG. 10, the sealing portion 215 surrounds or defines the opening 212. In this way, once the inlet pipe 218 is positioned within the opening 212, the sealing portion 215 is compressed between and against the pipe 218 and the end portion 206, forming a radial seal 220 therebetween.

Other structural features of the embodiment of Figure 120 are analogous, and are described as such, to the embodiments of the accompanying Figures 1 to 9.

Referring to the accompanying Figure 11, there is shown a partial cross-section of the first end cap 210 of the embodiment of Figure 10, in an uncompressed state. That is, the radial sealing portion 215 is shown where the filter element 200 is not installed in the air cleaner housing 20 and above the duct 218. Still referring to Figure 11, the radial sealing portion 215 defines a gradient of increasing inner diameter surfaces for interfacing with the air flow duct 218. Specifically, in the example shown in the accompanying Figure 11, the radial sealing portion 215 defines three steps, 235, 236, and 237. The cross-sectional dimension, or width, of the steps increases the further the step is from the top 240 of the first end cap 210. As shown, below the step 237 is a region 242 of reduced cross-sectional width.

C. Case 45

Attention is now drawn to Figure 2. In the attached Figure 2, one of the preferred embodiments of the housing 45 is shown. Preferably, the housing 45 is cylindrical with a cylindrical body 46 and a cover member 47.

Returning now to the accompanying Figure 3, the housing body 46 preferably includes an outer surrounding wall 150 and an axial bottom wall 152. The bottom wall 152 forms a closed end for the wall 150. The bottom wall 152 preferably includes an outlet

a pipe 28 extending therefrom and projecting therefrom to provide air communication with the interior 58 of the second element 54.

Opposite the bottom wall 152 is an open end 154 of the housing 45. The open end 154 is selectively opened and closed or covered or uncovered by a cover member 47. The cover member 47 is preferably mounted on the housing body 46 and is selectively either snapped therein or completely removed therefrom.

Preferably, and now referring to the accompanying Figure 2, the housing member 47 is selectively mounted on the open end 154 by clips 32. These clips 32 are preferably formed by eccentric clips that are evenly spaced around the outer circumference 156 of the open end 154 of the housing body. The eccentric clips 32 are preferably formed by spring metal clips and may be, for example, of the type described in U.S. Patent Application Serial No. 08/751,041, which is incorporated herein by reference.

The illustrated arrangement preferably utilizes three to eight clamps, and in this embodiment four clamps 32, which are evenly spaced around the circumference of the body 46 and the cover 47. Together, these clamps 32 provide a compressive force of at least 7 to 8 kilograms, and typically about 8 to 10 kilograms. This is sufficient to exert sufficient axial pressure on the element assembly 50 to form airtight seals 110,136 between the element assembly 50 and the housing 45.

Referring now to Figure 3, the housing 45 preferably includes a structure for centering the assembly of elements 50 therein. In the particularly preferred embodiment shown, the housing 45 includes a plurality of projecting members 160 extending axially from the bottom wall 152 of the housing body 46. Generally speaking, the projecting members or projections 160 preferably comprise upstanding posts 162 extending from the bottom wall 152. Each of the posts 162 preferably defines a bevel or tapered portion 164 that helps to provide a centering function. That is, due to the nature of the bevel or beveled portion 164, there is a leading edge that guides the assembly of elements 50 into proper orientation within the housing 45. Preferably, extending outwardly from the posts 162, are feet 165. These feet 165 maintain and support the assembly of elements 50 once it is oriented within the housing 45. Preferably, the height of the feet 165 is adjusted to effect only partial compression of the sealing member 130. In preferred arrangements, the height of the feet 165 is such that the compression of the sealing member 130 is no greater than seventy-five percent and is typically about fifty percent. In other words, one of the advantages of the legs 165 is that they prevent compression in the sealing member 130 and ensure that the upper sealing member 106 has sufficient compression to form the sealing closure 110, in an axial seal configuration. The height of the legs 165, that is, the distance from the bottom wall 152 to the top of each leg 165, is preferably about 0.5 millimeters, and in one example is 0.45 millimeters.

For a sealing member 130 having a cross-sectional thickness of approximately 67.8 millimeters, a leg height of approximately 4.8 millimeters results in a compression of the sealing member 130 of approximately fifty percent.

Preferably, the housing 45 includes a structure for mounting the housing 45 to a support structure. The support structure may include a number of different arrangements, such as a plate. One example of such a preferred mounting structure is shown in the accompanying Figure 8. The mounting structure preferably includes bolts arranged in a circle with a plurality of mounting locations 170. The mounting locations 170 preferably include clips or nuts 172 with an internally threaded collar for screwing in threaded bolts. The nuts 172 are suitably secured to the housing 45, such as by welding. Preferably, the mounting locations 170 are evenly spaced along the circumference 174 of the bottom wall 152. In the preferred embodiment shown in the accompanying Figure 8, there are a total of four mounting locations 170, spaced apart at an angle of approximately ninety degrees.

D. Methods for determining filter replacement and maintenance

A preferred embodiment of the air purifier 20 includes a means of communicating that the element assembly 50 requires maintenance or replacement. Attention is now directed to the accompanying Figure 7. In Figure 7, at reference numeral 180, one embodiment of a preferred system for indicating that a filter replacement is required and further for indicating whether or not the filter element assembly 50 is installed in the housing.

In Figure 7, the system 180 preferably includes a pressure fitting 182 that is positioned (from an airflow perspective) above the first filter element 52. A second pressure fitting 184 is preferably positioned just below (from an airflow perspective) the first filter element 52.

9999 ·· * 99 ·· 9 9 9 9 « 999 • 99 999 99 ···· 99 9 99 9 •9 99 99 ··· 99 999 air) by the first filter element 52, but above the second filter element 54. The third pressure fitting connection 186 is preferably arranged below the second filter element 54. Generally speaking, the pressure fitting connections 182,184,186 preferably include openings in the housing 45 that have a 3.175 millimeter (one-eighth inch) threaded tube with brass fittings for connecting hoses 194,195,196,197.

Preferably, a differential pressure switch 190 is disposed between the first pressure fitting 182 and the second pressure fitting 184. The differential pressure switch 190 indicates a pressure drop across the first filter element 52. Preferably, a second differential pressure switch 192 is disposed between the second pressure fitting 184 and the third pressure fitting 186. The second differential pressure switch 192 indicates a pressure drop across the second filter element 54. For example, switches of the type MPL-502, which are commercially available from Micro-Pneumatics Logic Inc. of Fort Lauderdale, Florida, may be used.

The reading of the differential pressure switch 190 indicates when the filter element assembly 50 should be replaced. Specifically, the pressure drop across the particulate filter 52 increases as the media 60 fills. When the pressure drop exceeds the set point on the switch 190, the switch will close, indicating the need to replace the element assembly 50.

The differential pressure switch 192 will indicate the presence or absence of the filter element assembly 50 and/or blockage of air flow through the entire system.

For example, if the inlet hose or pipe 22 or the outlet hose or pipe 30 (see attached Figure 1) becomes blocked, or if the discharge fan 16 stops operating, all of this will be indicated by the second differential pressure switch 192. Specifically, the pressure drop across the second filter element 54 will be above a certain minimum value if the filter element assembly 50 is present and if there is air flow. The pressure switch 192 will be closed if the filter element assembly 50 is installed and if there is air flow through the system.

When it is time to replace the filter element assembly 50, for example when the differential pressure switch 190 indicates that it is time for replacement with respect to • Φ φφφφ ΦΦ φ ΦΦ

ΦΦ φ φφφφ φφφ φφφ φφφ ΦΦ

ΦΦ φφφφ φφφφ φφφφ φφφ ΦΦ

ΦΦ ΦΦ «φ «ΦΦ ΦΦ φ filled particulate filter element 52, then the arrangement described herein serves for easy and quick filter replacement. Preferably, such replacement is performed every one or two weeks, with an estimated amount of 1.12 kilograms of particles trapped in the first filter element 52. Preferably, the life of the second filter element 54, serving to trap non-toxic gases, exceeds the life of the particulate filter element 52.

To replace the filter element assembly 50, the following steps are preferably performed. The cover 47 is removed from the housing 45. This is preferably done by releasing the clamps 32. Once the cover 47 is removed from the body 46, the tight connections 110,136 between the filter element assembly 50 and the housing 45 are broken. Removing the cover 47 exposes the first end cap 95 of the first filter element 52. The person performing the replacement then grasps the handle 75 attached to the filter element assembly 50. The handle 75 is rotated away from the end cap 95 and the filter element assembly 50 is lifted by the open end 154. First the first filter element 52 passes through this open end 154, followed by the second filter element 54.

The used filter element assembly 50 is then discarded. In some cases, it may be desirable to recycle certain particles that are captured in the first filter element 52.

The accumulated particulate material within the first filter element 52 remains within this interior space of the first filter element 52 and does not have the opportunity or access to an opening through which it could fall out of the interior 56.

A second, different new filter element assembly 50 is then prepared. The operator grasps the handle 75 of the new filter element assembly 50 and places it inside the housing 45. Specifically, the second filter element 54 passes through the open end 154 and is followed by the first filter element 52. The projections 160 help to center the filter element assembly 50 by centering the second end cap 121 on the bottom wall 152 of the housing 45. The air flow opening 125 in the second end cap 121 is positioned in air communication with the outlet conduit 28. The cover 47 is then oriented to close the open end 154 once it is positioned over the end of the filter element assembly 50. The inlet conduit 24 is positioned in air communication with the air flow opening 100 in the first end cap 95.

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The clamps 32 are then closed to secure the cover 47 to the body 46. Once the clamps are closed or tightened over the center of the assembly, axial pressure is applied between the filter element assembly 50 and the housing 45. This axial pressure causes an airtight seal 110 between the sealing member 106 and the cover 47 and creates a sealing joint 136 between the sealing member 130 and the bottom wall 152.

In preferred embodiments of the systems, the total time to perform a replacement of the filter element assembly 50 is less than five minutes, preferably less than three minutes.

E. Examples of materials

The following description provides examples of typical, and in some cases preferred, materials for the filter arrangement, it being understood that alternative materials may be used where appropriate.

The housing 45 is preferably formed of metal, for example steel, having a thickness of 1.1 millimeters.

The end caps 95,96 and 120,121 may also be formed from metal, for example from 1.1 millimeter thick galvanised steel.

The O-rings 107 and 132 and the sealing member 142 may be made of rubber, such as a Neoprene/EPDM/SBR sponge rubber. Components of this material have a compressibility such that they have about 25 percent deflection at a pressure of 2 to 5 psi (0.0014 to 0.0035 kilograms per square millimeter) and a hardness of about 30 to 45 Shore. They have a density of about 5 to 7 pounds per cubic foot (81.4 to 113.9 kilograms per cubic meter) and a tensile strength of 5.62 kilograms per square centimeter. They operate over a temperature range of about minus 56 to plus 120 degrees Celsius.

The device 60 may comprise a pleated device (filter), or alternatively a depth filter. If a pleated filter is used, a fibrous cellulose paper containing cellulose fibers and synthetic fibers may be used. The filter may be treated, for example, by oiling, as described in U.S. Patent No. 5,423,892, which is incorporated herein by reference. Or, for example, the filter may be treated with expanded polytetrafluoroethylene (PTFE). Also, as explained in • 9 ···· *· • * · « · 9

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In U.S. Patent No. 5,423,892, which is incorporated by reference, the effectiveness of a filter baffle, such as paper or cellulose, can be modified in some cases by applying relatively fine fibers, typically less than five microns and in many cases less than one micron (average), to the filter surface.

One preferred means 60 comprises a flame retardant air filter medium. This medium has the following properties:

Frazier throughput of approximately 15.25 meters per minute with an expected value in the range of 4.9 to 5.4 meters per minute;

/ dry breaking strength of at least 3.6 kg and expected values in the range of approximately 4 kg to 6.3 kg;

a wet breaking strength of at least 2 kg and expected values in the range of approximately 2.2 kg to 8.15 kg;

The base weight is not more than 36.2 kg / 278.7 square meters, and the expected values are in the range of approximately 33.5 kg to 35.8 kg / 278.7 square meters;

a wet tensile strength of at least 0.7 kilograms per square centimeter, and expected values are approximately 1.26 kilograms per square centimeter;

the pore size is no greater than about 55 microns, and typically ranges from about 48 to 53 microns;

The S corrugation has a size of at least 0.3 mm, and typically approximately 0.33 to 0.38 mm;

With dry tea at least 25 J/sq., and typically at least 30 J/sq.;

With a dust loading of at least 14.9 g/0.0929 square meter at 2.438 meters per minute, and typically about 16.7 g/0.0929 square meter;

a stiffness of at least 2000 mg, and typically at least 2400 mg;

/ fire retardant no more than 127 millimeters of char length and typically 50.8 millimeters to 101.6 millimeters.

The composition 64 is preferably formed of activated carbon impregnated with potassium iodide KJ for the purpose of absorbing formaldehyde gases. If only odor absorption were required (and formaldehyde gas absorption was not required), then the activated carbon need not be impregnated with potassium iodide KJ. The composition 64 preferably has the following properties:

CCI4 activity level, according to ASTM D - 3467 standard, at least 55% (basic);

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The moisture content according to ASTM D-2867 is not greater than about 15 percent to 22 percent;

The particle size according to ASTM D - 2862 is 6 x 12 US sieves.

The composition 64 preferably has a hardness of 97 according to ASTM D-3892.

Its bulk density is 0.60 grams per cubic centimeter according to ASTM D-2854. It has an ash content of three percent (basis) according to ASTM D-2866. It has a surface area, BET N2, of 1150 square meters per gram (basis). Composition 64 typically comprises coarse, granular particles having a mean diameter of approximately 1.6 millimeters.

In operation, the means 64 will remove formaldehyde gases such that the outlet of the air purifier 20 will contain less than 0.1 parts per million of formaldehyde in the air.

A preferred activated carbon is a commercially available product from Barnebey and Sutcliffe, based in Columbus, Ohio; it is sold under the name FormaSorb.

The inner and outer inserts 114,115 containing the composition may typically be made of a needle-punched, blended (fifty percent polypropylene and fifty percent modacrylic) electrostatic felt with the following properties: ν' Fomblin efficiency: 76 to 94 percent mean value, with no value lower than 71 or higher than 99; tested at an air flow of 3.15 meters per minute; particles were in the range of 0.3 to 0.4 microns.

/ Throughput: 86 to 145 meters per minute;

/ Thickness at a pressure of 3.5 kilograms per square meter: 0.91 to 1.55 millimeters; ν' Basis weight: 78 to 122 grams per square meter.

F. Example of a specific design

The following paragraphs describe one particular preferred example of an air purifier assembly. It is understood, however, that other alternative designs and dimensions may be used.

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In operation, the air purifier 20 will remove approximately one kilogram of particles after about one or two weeks of operation. The minimum air flow rate will be approximately 9.12 cubic meters per minute and the maximum air flow rate through the air purifier 20 will be approximately 25.9 cubic meters per minute.

The axial length between the end of the inlet pipe 24 and the outlet pipe 28 will be at least 0.5 meters and will typically be about 0.63 meters. The diameter of the inlet pipe 24 will be at least 2.5 centimeters, will not be greater than about 10 centimeters and will typically be about 4.4 centimeters. The diameter of the housing body 46 will be at least 30 centimeters, will not be greater than about 60 centimeters and will typically be about 40 centimeters. The axial length of the outlet pipe 28 will be at least 2.5 centimeters, will not be greater than about 10 centimeters and will typically be about 5 centimeters. The outlet pipe 28 will have a diameter of at least about 2.5 centimeters, will not be greater than about 10 centimeters and will typically be about three centimeters.

The assembly of elements 50 could have a total axial length of at least about thirty centimeters, not to exceed about 63.5 centimeters, and typically about 49 centimeters. The axial length of the first element 52 could be at least 25.4 centimeters, not to exceed about fifty centimeters, and typically about 41 centimeters. The axial length of the second element 54 would be at least 2.5 centimeters, not to exceed about 25.5 centimeters, and typically about 7.8 centimeters. The inner diameter of the first and second elements 52,54 would be at least 12.5 centimeters, not to exceed about thirty centimeters, and typically about 24.5 centimeters. The radial thickness of the device structures 60 and 64 would typically be at least 2.5 centimeters, not to exceed about ten centimeters, and typically about five centimeters. The outer diameter of the assembly of elements 50 will be at least 17.5 centimeters, will not be greater than about fifty centimeters, and will typically be about 35 centimeters. The diameter of the opening 100 in the first end cap 120 will be at least three centimeters, will not be greater than about ten centimeters, and will typically be about five centimeters. The diameter of the outlet opening 125 in the second end cap 121 will be at least about three centimeters, will not be greater than about ten centimeters, and will typically be about five centimeters.

The inner diameter of the sealing member 100 will be at least about 28 centimeters, will not be greater than about 34 centimeters, and will typically be about thirty centimeters. Seal

100 will typically have a radial thickness of at least 0.6 centimeters, not greater than about 3.18 centimeters, and typically about 1.9 centimeters. It will have a cross-sectional thickness of at least about 0.6 centimeters, not greater than about 1.3 centimeters, and typically about one centimeter.

The sealing member 130 will have dimensions similar to those of the sealing member 100.

The protrusions 160 will typically protrude at least 0.25 centimeters, no more than about five centimeters, and typically about 0.5 centimeters from the bottom wall 152.

The above data, examples and specifications provide a complete description of the manufacture and use of the present invention. Many other embodiments of the present invention may be made without departing from the spirit and scope of the present invention.

Claims (20)

Patent claims A filter element assembly comprising: (a) constructing the first device; said first means structure having first and second end caps at opposite ends and defining an open interior of the filter; (i) said first end cap is provided with an air flow aperture communicating with the air flow with said filter interior; and (ii) said second end cap that is closed from the air flow; (b) constructing a second device; said second means structure having first and second ends and defining an open interior space of the filter; (i) said second means structure is secured to said first means structure and stacked therewith in axial alignment; (ii) said structure of the second means having a first end which is closed to the air flow through the structure; and (iii) said second means structure having a second end provided with an air flow aperture communicating with the air flow with the open interior space of the second means structure filter; the second end of said second means is at the end of the filter element assembly opposite the first end cap of said first means structure. The filter element assembly of claim 1, wherein: (a) said construction of the second means comprises a first closed end cap at said first end; and a second end cap having an air flow opening at said second end. The filter element assembly of claim 2, wherein: (a) said first means structure is secured to said second means structure by spot welding. A filter element assembly according to either of claims 2 or 3, wherein: (a) said first device structure is cylindrical with an outer liner and an inner liner disposed between the first and second end caps of said first device structure; and (b) said second means structure is cylindrical with an outer liner and an inner liner disposed between the first and second end caps of said second means structure. A filter element assembly according to any one of claims 2 to 4, wherein: (a) a first end cap of said second device structure abuts the second end cap of said first device structure. A filter element assembly according to any one of claims 1 to 5, comprising: (a) a sealing member on the first end cap of said first means structure, defining an air flow opening in the first end cap of said first means structure. A filter element assembly according to any one of claims 2 to 6, comprising: (a) a sealing member on the second end cap of said second means structure, defining an air flow opening in the second end cap of said second means structure. A filter element assembly according to any one of claims 1 to 7, wherein: (a) said construction of the first means comprises folded paper. A filter element assembly according to any one of claims 1 to 8, wherein: (a) said construction of the second composition comprises activated carbon. An air cleaner having a filter element assembly according to any one of claims 1 to 9, comprising: (a) a housing having an interior space, an inlet conduit and an outlet conduit; and (b) said filter element assembly is removable and replaceable in said interior space of the housing; (i) wherein the airflow opening in the first end cap of said first means structure provides an air connection between said inlet line a housing conduit and an open interior of said first means structure; (ii) wherein the opening at the second end of said second device structure provides an air connection between the open interior space of said second device structure and an outlet conduit of said housing. The air cleaner of claim 10, wherein: (a) said housing includes a removable cover that provides access to the interior of the housing and filter element assembly. An air cleaner according to any one of claims 10 and 11, wherein: (a) said housing comprises a plurality of clamps for selectively securing said housing to the housing. An air cleaner according to any one of claims 10 to 12, wherein: (a) said housing comprises a plurality of protrusions along an inner wall of said housing. The air cleaner of claim 13, wherein: (a) said construction of the second means is centered between said protrusions. An air cleaner according to any one of claims 10 to 14, wherein: (a) said filter element assembly includes a handle secured thereto for orientation and removal of the filter element assembly within said housing. An air cleaner according to any one of claims 10 to 15, wherein: (a) said filter element assembly comprises a sealing arrangement for forming a seal between the filter element assembly and said housing. The air cleaner of claim 16, wherein: (a) said sealing arrangement comprises a first sealing member on said first end cap of a first means structure delimiting said inlet conduit; (I) said sealing member forms a seal between the structure of the first device and the housing of said housing when the cover of said housing is in the closed state. (b) said sealing arrangement comprises a second sealing member at said second end of the second means structure delimiting said outlet conduit; (i) said sealing member of the second filter element forms a seal between the structure of the second device and said housing. An air cleaner according to any one of claims 10 to 17, comprising: (a) a discharge fan assembly for directing the flow of air through said inlet duct to the interior of the first means structure, further by the first means structure, by constructing the second means into the interior of the second means structure, and outwardly through said outlet duct. An air cleaner according to any one of claims 10 to 18, comprising: (a) a first pressure outlet of said first means upstream structure; a second pressure outlet from the structure of the first means downstream of and above the structure of said second means; and a third pressure outlet from the structure of the second means downstream; (b) a first differential pressure switch, which is connected to said first and second pressure ports, to indicate a pressure drop on said structure of the first means; and (c) a second differential pressure switch, which is connected to said second and third pressure ports, to indicate a pressure drop on said structure of the second means. An air cleaner maintenance method according to claim 11, comprising the following steps: (a) removing the housing cover to expose access to the interior of the housing; the filter element assembly is oriented towards the inside of the housing; (b) gripping the handle on the filter element assembly; (c) pulling the filter element assembly through the handle through the opening; the first filter element passes through the opening first; and the second filter element passes through an opening after the first filter element.