Abstract:
A filter assembly for filtering viscous fluid materials, including a filter body having an inlet and an outlet, a filter element having an open end and a closed end and a collar structure at the open end. The collar structure is retainable proximate the inlet end such that fluid flows into an interior of the filter element through the open end. The filter assembly also includes a filter cap couplable to the filter body at the inlet end and a filter cap retaining structure to removably secure the filter cap to the filter body while substantially maintaining a relative rotational orientation between the filter cap and the filter body.

Description:
CLAIM TO PRIORITY  
       [0001]     This application claims priority to U.S. Provisional Patent Application Ser. No. 60/686,603 filed Jun. 2, 2005 entitled “Sealant Filter” the contents of which are incorporated in their entirety by reference. 
     
    
     FIELD OF THE INVENTION  
       [0002]     The invention relates generally to the field of filters for sealants and adhesives that are pumped through lines at high pressure.  
       BACKGROUND OF THE INVENTION  
       [0003]     Insulated glass is heavily utilized in modern residential and business construction. In many areas of the country it is required by building code as a mandatory energy conservation measure. A single pane of glass alone has very little insulating value. Multipane insulated glass windows have much greater insulating value.  
         [0004]     Insulated glass generally includes two panes of glass separated by a space. The perimeters of the two panes of glass are sealed to one another to eliminate movement of ambient air into the space between the two panes of glass. The space is filled with dehydrated air or with another form of gas.  
         [0005]     Traditionally, sealant applied to insulated glass window units have been silicone-based sealants. Silicone-based sealants require a curing time of between several hours and several days before they achieve substantial strength. This has led to the need for large storage facilities in the window and door manufacturing industry in order to allow finished units to set for a sufficient period of time to achieve substantial curing of the sealants before shipment or other handling. Thus, recently, there has been a move to change over to hot applied sealants to minimize curing time. The hot applied sealants and adhesives reduce the need to store completed window and door units while the sealant cures thus reducing overhead and the overall cost of producing windows and doors.  
         [0006]     However, hot applied sealant materials tend to include high levels of abrasives and corrosive components. Hot applied sealants generally include substantial concentrations of silicas and other abrasive materials. Thus, the use of hot applied sealants increases the level of wear on mechanical components used to pump, meter and dispense them.  
         [0007]     To remain fluid and to flow through pipes and hoses, hot applied sealant materials must be kept hot. Most hot applied sealant materials will remain fluid at temperatures between 200° and 300° Fahrenheit. In order to maintain hot applied sealant materials at an appropriate flowing temperature, the passages through which the hot applied sealant material passes must be heated. Insulation is applied to the exterior of the structures that form the passages to improve energy efficiency. Thus, the hoses through which hot applied sealant material flows are heavily insulated as well as equipped with heating elements to maintain the hot applied sealant at an appropriate temperature. All sealants, whether applied at ambient temperature or at elevated temperature are pumped at high pressures that require high strength hoses and fittings to contain the sealants. Thus, while all sealant hoses are unwieldy, stiff and somewhat difficult to handle insulated, heated hoses are especially difficult in this regard.  
         [0008]     In addition, hot applied sealant materials often contain or may contaminated with undesirable foreign material or particulate matter that may find its way into the hot applied sealant material prior to its entry into the application equipment.  
         [0009]     Factories in which hot applied sealant materials are used commonly also house cutting tools that may create shavings, chips, sawdust or other particulate matter that can get into the hot applied sealant. The pumps and metering devices that are used in equipment for applying hot applied sealant materials include many devices which operate at high pressure and have closed tolerances between moving parts. Thus, foreign material that may find its way into the hot applied sealant material, at worst, can destroy pumps, valves and metering devices that are utilized in the application of the hot applied sealant. At best, the useful life of the close tolerance, high pressure equipment will be shortened substantially by the presence of foreign material in the hot applied sealant materials.  
         [0010]     Thus, it becomes important to filter hot applied sealant material when it is in its fluid state prior to the hot applied sealant material encountering the close tolerance machinery in the application equipment.  
         [0011]     When filters are utilized with hot applied sealant materials the filters must be changed periodically as they become clogged. Because the filters and the hot applied sealant material must be maintained at a fluid temperature to allow changing of the filters, there is a certain risk to personnel who are changing the filters. Burns may occur from contact with the hot equipment or fluids. Personnel must be protected from burns that might occur from handling the hot melt filter as well as the hot melt material. Thus, personnel generally wear heavy gloves and other protective clothing that may limit dexterity.  
         [0012]     Another problem that arises with filters for hot melt material is that most filters available today that are suitable for this application are arranged so that fluid flows in one end of the filter apparatus passes through the filter element from the outside of the element to the inside of the element and out through an outlet. This leaves particulate matter trapped outside of the filter element in a surrounding container. A filter of this type is disclosed for example in U.S. Pat. No. 5,916,435 issued to Spearman, et al. This arrangement does not present a particular problem when utilized with ordinary fluids that are liquid at room temperature. However, with a hot melt fluid it becomes necessary for the operator to remove the hot melted sealant, which is still very hot, from the inside of the container to remove all the particulate matter from the filter. If the particulate contaminated sealant is not removed the remaining particulate matter will tend to immediately clog the newly replaced filter element.  
         [0013]     Thus, it is preferable to arrange a filter so that fluid flows in an inlet to the inside of a cylindrical or conical filter element, out through the filter element and then out through an outlet. This causes particulate matter to be trapped within the filter element so the filter element can be removed and discarded taking the particulate matter with it. A filter of this type is disclosed in U.S. Pat. No. 5,536,402 issued to Kluhsman.  
         [0014]     Filters of the type disclosed in Kluhsman still have a continuing problem however, in that, as previously mentioned, the hoses utilized in hot melt application equipment are thick and relatively inflexible. A filter of the type disclosed in the Kluhsman reference requires that the ends of the filter container be removed to gain access to the filter element so that it can be removed and discarded or cleaned. This becomes very difficult with prior art filters because the filter element must be disconnected from the hoses prior to any removal to gain access to the filter element.  
         [0015]     In addition, currently available filters are not well adapted to being connected to heating elements in order to maintain the hot applied sealant materials in a fluid state. Further still, currently available filters are not well adapted to accommodate heat sensors to allow for maintenance of the filter element and the contained hot melt sealant material at an appropriate high temperature.  
         [0016]     Thus, the sealant application industry would benefit significantly from a filter element that is adapted to operate at high pressures that is readily accessible for changing the internal filter element without the need to entirely disconnect the filter assembly from the heavy and relatively inflexible ambient temperature or hot melt sealant hoses. In addition, it would be beneficial if the filter was of a type that minimizes the necessity to clean out the inside of the filter assembly housing. Further, it would be beneficial to the hot melt sealant application industry if the filter element was readily removed for discard while minimizing danger to personnel removing the filter due the high temperature of the contents of the filter element and hoses.  
       SUMMARY OF THE INVENTION  
       [0017]     The sealant filter of the present invention solves many of the above problems. The sealant filter generally includes a filter body, a filter cap, a filter shoulder, a retaining nut and a filter element. The filter body is preferably of sufficient strength to withstand a pressure of up to about 3,000 lb/inch 2 . The filter body of the present invention may be formed of stainless steel or another high strength, preferably metallic, material. A metallic material also allows the filter body to transmit heat efficiently from a heating element to maintain the temperature of hot applied sealants that are kept within. The filter cap covers an open end of the filter body to provide an enclosure for the filter element.  
         [0018]     The filter of the present invention is configured so that the inlet is located in the filter cap and the outlet is located in an opposite end of the filter body. The filter element is inserted into the filter body from the open end when the filter cap is removed so that fluid flows through the inlet into the interior of the filter element out through the walls of the filter element then through the interior of the filter body and out the outlet. In this way, foreign material is trapped within the filter element and is readily discarded along with the filter element.  
         [0019]     The retaining nut may be threaded onto the filter body at the open end thereof in such a way that the retaining nut secures and clamps the filter cap against the open end of the filter body and the open end of the filter element is secured at the open end of the filter body. It is particularly notable in the present invention that the retaining nut is unscrewable separately from the filter cap so that the retaining nut may be turned without the necessity to turn the filter cap and therefore without the necessity to turn or remove a hose connected to the filter cap.  
         [0020]     In addition to the outlet, the filter body may include a threaded receptacle for receiving a pressure gauge attached thereto. The pressure gauge is valuable for determining a pressure drop across the filter element. When the pressure drop reaches a predetermined level it signals the need to replace the filter element because it has become clogged.  
         [0021]     The filter element of the present invention may be substantially rigid or semi-rigid and may be made of stainless steel mesh or another material adapted to an application that involves high pressure and temperature. The filter element may be substantially circular at one end and may be flattened to a tapered closed end. The filter element may be available in, for example, 30, 60 and 100 mesh sizes. The filter element may be formed from woven material and have a crimped and welded construction. In addition, the filter element may take the form of a perforated or sintered sheet formed to the necessary shape.  
         [0022]     Thus, the present invention provides a filter assembly that entraps undesirable particulate debris within the filter element so that the filter element can be removed and discarded without the necessity to clean particulate debris out of the filter assembly itself. In addition, the filter assembly of the present invention can be readily disassembled for replacement of the filter element without the necessity to disconnect the filter assembly from hoses that may be attached thereto. Further, the filter assembly can be disassembled without the need to rotate the filter assembly relative to the hoses that it is connected to.  
         [0023]     In addition, in one embodiment, the filter assembly includes a drip edge built into the open end of the filter body that prevents fluid from dripping on to the threads to which the retaining nut attaches thereby preventing sealant from following the threads of the retaining nut.  
         [0024]     In another embodiment, the filter assembly includes a multi-piece external collar that may be applied to secure the filter cap to the filter body instead of a retaining nut. The multi-piece external collar may be easier to remove and apply in applications where the filter assembly is located in close quarters because it eliminates the need to swing a large wrench. The multi-piece external collar may include two or more pieces that are assembled together to secure the filter cap to the filter body. In one embodiment of the invention, the multi-piece external collar includes four similar sections that are assembled into a boxlike, four sided external collar to secure the filter body to the filter cap. In addition, because of the high pressures involved in sealant dispensing systems the securement between the filter cap and the filter body needs to withstand the elevated pressures.  
         [0025]     Thus, the features of the filter assembly make it easy to open and easy to clean or replace the filter element making it better suited than prior art filters to use with high pressure application of sealants at ambient elevated temperatures. The invention is especially useful when applied is situations that employ hot melt sealants and adhesives. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0026]      FIG. 1  is a perspective view of a sealant filter in accordance with the present invention.  
         [0027]      FIG. 2  is a cross-sectional perspective view of the sealant filter.  
         [0028]      FIG. 3  is a perspective view of a sealant filter in accordance with the present invention with parts removed for clarity.  
         [0029]      FIG. 4  is a plan view of a filter body in accordance with the present invention.  
         [0030]      FIG. 5  is a cross-sectional view of the filter body taken along section line  5 - 5  of  FIG. 4 .  
         [0031]      FIG. 6  is a perspective view of a filter cap in accordance with the present invention.  
         [0032]      FIG. 7  is an elevational view of the filter cap.  
         [0033]      FIG. 8  is a plan view of the filter cap of  FIG. 7  with internal structures depicted in phantom.  
         [0034]      FIG. 9  is a perspective view of another embodiment of the sealant filter in accordance with the present invention.  
         [0035]      FIG. 10  is a perspective cross sectional view of the sealant filter depicted in  FIG. 9 .  
         [0036]      FIG. 11  is an exploded view of the sealant filter depicted in  FIG. 9 .  
         [0037]      FIG. 12  is an end elevational view of the sealant filter depicted in  FIG. 9 .  
         [0038]      FIG. 13  is a cross sectional view taken along section line  13 - 13  of  FIG. 12 .  
         [0039]      FIG. 14  is a partial exploded view of the sealant filter of  FIG. 9 .  
         [0040]      FIG. 15  is a plan view of a four piece external collar in accordance with the present invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0041]     Referring to  FIGS. 1-6  an embodiment of sealant filter  20  generally includes filter body  22 , filter cap  24 , retaining nut  26  and filter element  28 . Sealant filter  20  may also include mounting bracket  30 , temperature sensor  32 , sensor clamp  34  and pressure gauge  36 .  
         [0042]     Referring particularly to  FIG. 2 , filter body  22  defines inlet  38 , outlet  40  and gauge port  42 . Filter body  22  also defines cavity  44 . Filter body  22  may be formed of a material capable of containing high pressures such as, but not limited to, stainless steel. Outlet  40  and gauge port  42  may be threaded to receive threaded attachments to fittings. Other coupling arrangements known in the art may also be utilized. Inlet  38 , outlet  40  and gauge port  42  are all in fluid communication with cavity  44 . Desirably, the end of filter body  22  surrounding inlet  38  defines drip edge  52  about inlet  38 .  
         [0043]     Filter element  28  is dimensioned to fit within cavity  44 . Filter element  28  generally includes collar portion  46  and sieve portion  48 . Sieve portion  48  may be formed from stainless steel mesh, perforated or sintered metal, ceramic or another durable material in various sizes. For example, sieve portion  48  may be made of 30, 60 or 100 mesh of stainless steel mesh material. Collar  46  is substantially circular in form and may rest on filter holder  50 . Filter holder  50  may be formed of a resilient gasket material or of a somewhat malleable material such as brass, copper or bronze to facilitate sealing.  
         [0044]     Filter cap  24  defines inlet  38  and is dimensioned to secure collar portion  46  of filter element  28  into filter body  22 . Inlet  38  may be threaded to receive fittings. It is notable, in this embodiment, that filter cap  24  is separate and independent from retaining nut  26  and that filter cap  24  does not turn with retaining nut  26  when retaining nut  26  is turned.  
         [0045]     Retaining nut  26  may be threadedly engageable to filter body  22  and may secure filter cap  24  to filter body  22 . Retaining nut  26  may also include an interrupted thread or other engagement structure known to those skilled in the art.  
         [0046]     Filter shoulder  50  is sized to be interposed between collar portion  46  and filter body  22 . Filter shoulder  50  is a substantially ring-shaped structure formed of a resilient gasket material or of a somewhat malleable material such as brass, copper or bronze to facilitate sealing.  
         [0047]     Sealant filter  20  is desirably formed of a material tolerant to high pressure as well as elevated temperature. Hot applied sealant materials typically must be maintained at a temperature of 200°-300° Fahrenheit and sealant filter  20  should be formed of a material that can tolerate that temperature for a long period of time. For example, stainless steel is one material from which sealant filter  20  may be formed.  
         [0048]     Referring to  FIGS. 2, 4 , and  5 , filter body  22  may further define clamp groove  54 . Clamp groove  54  may include flat portion  56  and depressed portion  58 . Filter cap  24  may be sealed to filter body  22  by O-ring  60  received into O-ring groove  62 . O-ring groove  62  may be formed in either filter body  22  or filter cap  24 .  
         [0049]     Referring to  FIGS. 6, 7  and  8 , filter cap  24  defines outer wall  64 , inner wall  66 , wrench flats  68  and filter collar receiving shelf  70 . Inlet  38  of filter cap  24  may include threaded portion  72 . Threaded portion  72  is adapted to receive fittings from connecting hoses or pipes.  
         [0050]     Referring to  FIGS. 9-15 , another embodiment of sealant filter  20  is depicted. In this embodiment, sealant filter  20  includes filter body  74 , filter cap  76  and retaining collar  78 . Filter element  28  is similar to that described above.  
         [0051]     Referring particularly to  FIGS. 10, 11 ,  13 , and  14 , desirably filter body  74  is a generally cylindrical structure. Filter body  74  is structured to contain fluids at high pressure of about three thousand pounds per square inch. Filter body  74  defines retaining groove  80  and cap receiving portion  82 . Retaining groove  80  runs circumferentially around the exterior of filter body  74 . Cap receiving portion  82  is recessed and sized to receive a portion of filter cap  76 .  
         [0052]     Filter cap  76  includes hex portion  84 , retaining shoulder  86 , retaining groove  88 , o-ring groove  90 , tapered portion  92 , and filter collar receiver  94 . Retaining shoulder  86  and retaining groove  88  are robustly constructed to resist the stresses created by elevated pressures.  
         [0053]     Retaining collar  78  includes collar segments  96 . As depicted here, retaining collar  78  is made up of four collar segments  96 . However, retaining collar  78  may be formed of at least two collar segments  96  and may include a larger number of collar segments than four.  
         [0054]     Retaining collar  78 , as depicted here, is made up of four similar collar segments  96 . Collar segments may also be dissimilar in structure. Each collar segment  96  includes retaining ridges  98 , plate  100 , knuckles  102 , and barrel  104 . Retaining ridges  98  protrude from plate  100 . Retaining ridges  98  may be curved to conform to a segment of a cylinder in order to closely fit filter body  74  and filter cap  76 . In this embodiment, two knuckles  102  protrude from plate  100  at a first end and barrel  104  protrudes from plate  100  at a second end. Barrel  104  is sized to fit into a space between knuckles  102 . Knuckles  102  and barrel  104  are pierced by bore  106 .  
         [0055]     Bolt  108  may be passed through bore  106  to secure collar segments  96  together. Bolt  108  may be secured in place with nut  110 .  
         [0056]     In operation, sealant filter  20  is secured into a line for hot melt or ambient temperature sealant materials. Hot melt or ambient temperature sealant materials flow in through inlet  38  and out through outlet  40 . Undesirable debris is trapped on the inside of filter element  28 .  
         [0057]     When it becomes necessary to replace filter element  28  an operator may unscrew retaining nut  26  and disengage filter cap  24  from filter body  22 . An operator may then reach into cavity  44  to grasp filter element  28  with a tool such as needle nose pliers to remove filter element  28 . Filter element  28  may be cleaned or discarded and a new filter element  28  or clean filter element  28  may be inserted into cavity  44 .  
         [0058]     Advantageously, retaining nut  26  can be unscrewed and filter cap  24  separated from filter body  22  to replace filter element  28  without the need to disconnect unwieldy hoses from sealant filter  20 . In addition, temperature sensor  32  may be secured to sealant filter  20  at sensor clamp  34 .  
         [0059]     Drip edge  52  lessens the chance that sealants dripping from cavity  44  will get onto and foul threads where retaining nut  26  engages filter body  22 .  
         [0060]     Referring to  FIGS. 9 through 15 , in one embodiment of the invention, sealant filter  20  may be secured into a line for hot melt sealant materials. When it is desired or necessary to replace filter element  28 , an operator may unscrew nut  110  from one of bolts  108  and remove one of bolts  108  from bore  106  to release the connection between knuckles  102  and barrel  104 . Remaining bolts  108  and nuts  110  may be loosened as necessary to hingedly open retaining collar  78  by bending color segments  96  appropriately.  
         [0061]     Filter cap  76  may then be pulled straight out from filter body  74  to expose filter element  28 . Notably, filter cap  76  is removable from filter body substantially without altering the rotational orientation between filter cap  76  and filter body  74 . Filter element  28  may be removed from the interior of filter body  74  by grasping it with a tool such as needle nose pliers.  
         [0062]     When filter element  28  is removed, trapped particulate matter along with hot melt sealant that may be contaminated by trapped particular matter is removed with it retained inside of filter element  28 .  
         [0063]     An operator may then insert a new or clean filter element  28  into filter body  74  and reconnect filter cap  76  by inserting it straight into filter body  74 . Retaining collar  78  may then be replaced to secure filter cap  76  to filter body  74  by reversing the above-described removal procedure.  
         [0064]     In an advantageous aspect of the invention, when filter body  74  and filter cap  76  are separated, there is no necessity to rotate them relative to one another, thus making it easier to separate them to replace filter element  28  when dealing with heavy, stiff hoses that are required for hot melt sealants.  
         [0065]     The present invention may be embodied in other specific forms without departing from the spirit of the essential attributes thereof; therefore, the illustrated embodiments should be considered in all respects as illustrative and not restrictive, reference being made to the appended claims rather than to the foregoing description to indicate the scope of the invention.