Abstract:
A coalescing filter assembly having an upstream chamber, a downstream chamber, and a weephole connecting the upstream chamber to the downstream chamber. The downstream chamber includes a coalescing filter to filter a flow of gases. A passageway may be implemented between the upstream chamber and the downstream chamber to accommodate the flow of gases therethrough, while the weephole enables liquid to seep from the upstream chamber to the downstream chamber. In this manner, the weephole reduces liquid pooling in the upstream chamber without substantially compromising the efficiency or performance of the coalescing filter. A drain may connect to the downstream chamber to drain liquid collected therein.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     This invention relates to filtration systems, and more particularly relates to a coalescing filter assembly to reduce liquid pooling therein.  
         [0003]     2. Description of the Related Art  
         [0004]     Diesel engines require less maintenance and generate energy more efficiently, with less carbon dioxide emissions, than gasoline-powered engines. As a result, more than thirteen million diesel engines in the United States provide power for a wide range of vehicles and equipment including heavy-duty trucks, buses, trains, large ships, electricity generators, excavators, cranes, and agricultural equipment.  
         [0005]     Diesel emissions, however, are more harmful to human health on a per-vehicle basis than emissions from similar gasoline-powered engines. Indeed, even though diesels comprise only about five percent (5%) of on-road vehicles in the United States, on-road diesels released 3.4 million tons of nitrogen oxides (NO x ) in 2002, accounting for thirteen percent (13%) of all U.S. NO x  emissions.  
         [0006]     Accordingly, the Environmental Protection Agency (“EPA”) has finalized regulations requiring substantially more stringent emissions limits for on-road heavy-duty diesel engines, where crankcase gases are included as part of the regulated diesel engine emissions. While various types of filters have been engine-mounted in tight spaces for many years, the new EPA emissions regulations require that crankcase ventilation systems, exhaust gas recirculation (“EGR”) systems, and other components also be engine-mounted.  
         [0007]     Engine surface space is inherently limited. Accordingly, compliance with the new EPA emissions regulations requires that engine-mounted devices overcome challenging packaging and mounting constraints. For example, conventional coalescing filter assemblies include void spaces in front of the filter element that tend to collect oil and other liquid and solid contaminants before filtration. The volume of liquid collected in those spaces may flood portions of the filter and cause oil leakage during vehicle operation. Additionally, liquid accumulated in such voids may spill out when the filter is replaced or the engine is otherwise serviced, rendering otherwise simple servicing procedures both difficult and messy. These problems are exacerbated by the increasingly limited working space available for accessing engine-mounted devices subject to the new EPA regulations.  
         [0008]     What is needed is thus an engine-mounted coalescing filter assembly that reduces oil leaks and spills during operation and servicing while substantially maintaining filter performance and efficiency. Beneficially, such an engine-mounted coalescing filter assembly would also facilitate mounting and packaging requirements under the new EPA regulations. Such a coalescing filter assembly is disclosed and claimed herein.  
       SUMMARY OF THE INVENTION  
       [0009]     The present invention has been developed in response to the present state of the art, and in particular, in response to the problems and needs in the art that have not yet been fully solved by currently available coalescing filtration systems. Accordingly, the present invention has been developed to provide a coalescing filtration system that overcomes many or all of the above-discussed shortcomings in the art.  
         [0010]     A coalescing filter assembly to reduce liquid pooling therein in accordance with certain embodiments of the present invention includes a coalescing filter having an upstream chamber, a downstream chamber, and a weephole connecting the upstream chamber to the downstream chamber. The coalescing filter is adapted to filter a gaseous stream in a direction from the upstream chamber to the downstream chamber, and may include a passageway to accommodate the gaseous stream. A coalescing filter medium may reside within the downstream chamber to filter the gaseous stream and coalesce liquid therefrom.  
         [0011]     The weephole, measuring between about one and about five millimeters in diameter, may function to enable liquid pooling in the upstream chamber to seep to the downstream chamber. In one embodiment, the upstream chamber includes a perforated partition to slow a velocity of the gaseous stream as it enters the upstream chamber. The perforated partition includes a channel to enable liquid to seep through the partition to communicate with the weephole. The liquid may then drain from the downstream chamber to, for example, an engine crankcase, by way of a drain connected to the downstream chamber.  
         [0012]     A system of the present invention is also presented to reduce liquid pooling therein. The system may be embodied by an upstream chamber, a downstream chamber, a passageway, a filter medium, and a weephole. As in the coalescing filter assembly, the passageway connects the upstream chamber to the downstream chamber and accommodates the flow of gases. The filter medium resides within the downstream chamber to filter the gases as they flow through the passageway.  
         [0013]     The weephole connects the upstream chamber to the downstream chamber to enable liquid pooling in the upstream chamber to seep to the downstream chamber. In one embodiment, a drain connects the downstream chamber to an engine crankcase to direct liquid collected in the downstream chamber to the crankcase. In another embodiment, the upstream chamber includes a perforated partition that includes a channel to enable liquid to seep through the partition to communicate with the weephole.  
         [0014]     A method of the present invention is also presented to reduce liquid pooling in a coalescing filter assembly. In one embodiment, the method includes providing an upstream chamber and a downstream chamber, connecting the upstream chamber to the downstream chamber via a passageway, and engaging within the downstream chamber a filtration medium to filter gases flowing through the passageway. The method further includes forming within the upstream chamber a weephole to enable liquid pooling in the upstream chamber to seep from the upstream chamber to the downstream chamber.  
         [0015]     In certain embodiments, the method further includes sizing the weephole to a diameter in a range between about one and about five millimeters. The method may also include coupling to the downstream chamber a drain to enable liquid collected in the downstream chamber to drain therefrom. In one embodiment, the method includes partitioning the upstream chamber to slow a velocity of gases entering the upstream chamber and forming within the partition a channel to enable liquid to seep through the partition to communicate with the weephole.  
         [0016]     In an alternative embodiment, a method to reduce liquid pooling in a coalescing filter includes introducing a gaseous stream to an upstream chamber in a coalescing filter assembly. The method further includes directing the gaseous stream from the upstream chamber to a downstream chamber via a passageway connecting the upstream chamber to the downstream chamber. Further steps of the method include filtering the gaseous stream flowing through the passageway and enabling liquid pooling in the upstream chamber to seep through a weephole connecting the upstream chamber to the downstream chamber.  
         [0017]     Reference throughout this specification to features, advantages, or similar language does not imply that all of the features and advantages that may be realized with the present invention should be or are in any single embodiment of the invention. Rather, language referring to the features and advantages is understood to mean that a specific feature, advantage, or characteristic described in connection with an embodiment is included in at least one embodiment of the present invention. Thus, discussion of the features and advantages, and similar language, throughout this specification may, but do not necessarily, refer to the same embodiment.  
         [0018]     Furthermore, the described features, advantages, and characteristics of the invention may be combined in any suitable manner in one or more embodiments. One skilled in the relevant art will recognize that the invention may be practiced without one or more of the specific features or advantages of a particular embodiment. In other instances, additional features and advantages may be recognized in certain embodiments that may not be present in all embodiments of the invention.  
         [0019]     These features and advantages of the present invention will become more fully apparent from the following description and appended claims, or may be learned by the practice of the invention as set forth hereinafter.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0020]     In order that the advantages of the invention will be readily understood, a more particular description of the invention briefly described above will be rendered by reference to specific embodiments that are illustrated in the appended drawings. Understanding that these drawings depict only typical embodiments of the invention and are not therefore to be considered to be limiting of its scope, the invention will be described and explained with additional specificity and detail through the use of the accompanying drawings, in which:  
         [0021]      FIG. 1  is a perspective view of coalescing filter assembly constituents in accordance with certain embodiments of the present invention;  
         [0022]      FIG. 2  is a cross-sectional perspective view of the internal components of a coalescing filter assembly depicting the directional flow of gas therethrough;  
         [0023]      FIG. 3  is a cross-sectional view of a coalescing filter assembly in accordance with the present invention showing areas prone to liquid pooling;  
         [0024]      FIG. 4  is a cross-sectional perspective view of one embodiment of a weephole integrated into a coalescing filter assembly in accordance with the present invention;  
         [0025]      FIG. 5  is a perspective view of an inverted cover showing a channel integrated between the access chamber and the upstream chamber in accordance with the present invention; and  
         [0026]      FIG. 6  is a cross-sectional perspective view of a coalescing filter assembly having a channel integrated into a partition thereof in accordance with certain embodiments of the present invention.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0027]     Reference throughout this specification to “one embodiment,” “an embodiment,” or similar language means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases “in one embodiment,” “in an embodiment,” and similar language throughout this specification may, but do not necessarily, all refer to the same embodiment.  
         [0028]     Furthermore, the described features, structures, or characteristics of the invention may be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are disclosed to provide a thorough understanding of embodiments of the present invention. One skilled in the relevant art will recognize, however, that the invention may be practiced without one or more of the specific details, or with other methods, components, materials, and so forth. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of the invention.  
         [0029]     As used in this specification, the term “coalesce” refers to a process in which a gaseous suspension of fine solid or liquid particles comes in contact with fibers in a filter media, the suspended particles combine with other collected particles, and the combined particles emerge as a droplet on a downstream surface of the media. The term “coalescing filter” or simply “filter” refers to a filter or other high efficiency separator capable of removing entrained liquid aerosols and other fine contaminants from a gaseous stream. The term “gaseous stream” or “gases” refers to air, combustion off or blow-by gases, crankcase gases, or other carrier gases for aerosols known to those in the art.  
         [0030]     Referring now to  FIG. 1 , a coalescing filter assembly  100  in accordance with the present invention may comprise a housing  102  adapted to reduce liquid pooling on an upstream side of a coalescing filter disposed therein. In one embodiment, the housing  102  comprises a three-part assembly including a cover  104 , a base  106  and a divider  108 . The divider  108  may substantially divide the space between the cover  104  and the base  106 , forming an upstream chamber  110  substantially disposed between the cover  104  and the divider  108 , and a downstream chamber  112  substantially disposed between the divider  108  and the base  106 . A coalescing filter medium (not shown) may reside within the downstream chamber  112  to filter a gaseous stream.  
         [0031]     The gaseous stream may be introduced to the housing  102  by way of an inlet  120  in communication with the upstream chamber  110 . The inlet  120  may be integrated into a wall  128  of the housing  102 . In certain embodiments, the inlet  120  may further communicate with a source of unfiltered aerosol, such as the engine crankcase (not shown).  
         [0032]     In one embodiment, the upstream chamber  110  includes an access chamber  114  immediately adjacent the inlet  118 . The access chamber  114  may be defined by corresponding walls  128   a ,  128   b  of each of the cover  104  and base  106  elements, as well as by corresponding partitions  116   a ,  116   b  integrated into the cover  104  and base  106 . A junction between corresponding walls  128   a ,  128   b  and corresponding partitions  116   a ,  116   b  may be mediated by seals  134  integral to the divider  108 . Alternatively, the access chamber  114  may be defined by a unitary partition  116  between the cover  104  and the base  106 , by an independent chamber in remote communication with the upstream chamber  110 , or by any other means known to those in the art.  
         [0033]     In certain embodiments, the base partition  116   b  may be substantially impervious to the gaseous stream, while the cover partition  116   a  may include perforations  118  directing the gaseous stream into the upstream chamber  110 . In this manner, the access chamber  114  may function to slow a velocity of incoming gases entering the upstream chamber  110 .  
         [0034]     In some embodiments, the combined partition  116  may also function to substantially isolate incoming gases to facilitate a pressure reading of gases within the access chamber  114 . Indeed, in some embodiments a pressure gauge  132  may be integrated into the housing  102  to communicate with the access chamber  114 . The pressure reading obtained from the access chamber  114  may be applied to approximate a pressure within, for example, the engine crankcase or other ancillary source of incoming gases, as well as to determine a pressure within the access chamber  114  itself.  
         [0035]     The divider  108  may comprise one or more passageways  124  to facilitate a flow of gases between the upstream chamber  110  and the downstream chamber  112 . As previously mentioned, a coalescing filter medium (not shown) may reside within the downstream chamber  112  and, in some embodiments, may be coupled to the divider  108 . In this manner, the coalescing filter medium may filter a gaseous stream flowing through the passageway  124  in a direction from the upstream chamber  110  to the downstream chamber  112 . An outlet  122  may be integrated into the housing  102  and communicate with the downstream chamber  112  to enable filtered gases to exit the coalescing filter assembly  100 .  
         [0036]     The divider  108  may be retained between the cover  104  and base  106  by pressure, or by any other means known to those in the art. Similarly, the cover  104  may attach to the base  106  by any attachment means known to those in the art. In one embodiment, the cover  104  may be bolted to the base  106 , and the divider  108  clamped therebetween.  
         [0037]     Referring now to  FIG. 2 , gases may flow across the coalescing filter assembly  100  of the present invention in a direction from inlet  120  to outlet  122 . Specifically, the inlet  120  may focus gases originating from an ancillary device or location, such as from an engine crankcase (not shown), to form a gaseous stream  200 . Where the coalescing filter assembly  100  includes an access chamber  114 , the gaseous stream  200  may proceed from the inlet  120  to the upstream chamber  110  via the access chamber  114 . As discussed above, a partition  116  forming a portion of the access chamber  114  may include perforations  118  enabling the gaseous stream  200  to exit the access chamber  114  to the upstream chamber  110 . In other embodiments, the gaseous stream  200  may flow directly from the inlet  120  to the upstream chamber  110 .  
         [0038]     A passageway  124  integrated into the divider  108  may enable the gaseous stream  200  to enter the downstream chamber  112 . A coalescing filter medium  126  disposed within the downstream chamber  112  may filter a flow of the gaseous stream  200  as it traverses the passageway  124 . The filtered gaseous stream  200  may then exit the coalescing filter assembly  100  of the present invention through the outlet  122 .  
         [0039]     Traditionally, the flow of gases through a coalescing filter assembly  100  as outlined above has resulted in gravitational pooling of liquid upstream of the coalescing filter medium  126 . Referring now to  FIG. 3 , the areas of the coalescing filter assembly  100  particularly susceptible to upstream liquid pooling include a first area  300  located below a passageway  124  integrated into the divider  108 , and a second area  302  located in a lower portion of the access chamber  114 .  
         [0040]     The first area  300  may collect liquid as a result of microdroplet condensation on an upstream side of the divider  108 . In one embodiment, the divider  108  includes multiple elongate passageways  124  providing crankcase gases access to a coalescing filter medium  126  located in the downstream chamber  112 . Gases entering the passageways  124  may be heavy laden with oil and other heavy hydrocarbons. Indeed, while fuel gas from the engine is typically well dispersed before it settles, crankcase gases are typically much less dilute and may create local areas of high concentration. As a result, microdroplets of oil and other liquid and particulate matter may coat the divider  108  and passageways  124  as the gases come in contact therewith. The microdroplets may accumulate in a first area  300  defined by a lower portion of the upstream chamber  110 , potentially flooding the passageways  124  and/or the coalescing filter medium  126  in contact therewith.  
         [0041]     The second area  302  may collect liquid in a similar manner. For example, in another embodiment, gases entering the access chamber  114  may be saturated with oil and other liquid or particulate contaminants. The oil and other contaminants may condense onto the partition  116  and/or other walls of the access chamber  114 , finally pooling in the second area  302 . Such pooling may cause messy spills when the coalescing filter medium  126  is replaced or the coalescing filter assembly  100  is otherwise serviced.  
         [0042]     Referring now to  FIG. 4 , a weephole  400  may be provided in the divider  108  to enable an accumulation of liquid in the first area  300  to seep from the upstream chamber  110  to the downstream chamber  112 . In this manner, the weephole  400  may reduce filtration inefficiencies resulting from liquid flooding portions of the passageway  124  and coalescing filter medium  126 .  
         [0043]     The weephole  400  may comprise a diameter between about one and about five millimeters, where the diameter of the weephole  400  may be selected to facilitate liquid seepage while limiting filter inefficiencies resulting from gases circumventing the passageways  124  and coalescing filter medium  126 . In one embodiment, the weephole  400  may be formed substantially adjacent to seals  404  sealing a bottom edge  406  of the divider  108  between the cover  104  and base  106 . In other embodiments, the weephole  400  may be located proximate a bottom edge  406  of the divider  108 , or in any other location known to those in the art.  
         [0044]     In one embodiment, the bottom edge  406  of the divider  108  substantially corresponds to a bottom edge of the upstream chamber  110  and is substantially arc-shaped, with the lowest point of the arc substantially corresponding to the position of the weephole  400 . This design promotes efficient disposal of liquid accumulation into the downstream chamber  112 . Indeed, liquid accumulation from the gaseous stream may collect towards the weephole  400  and seep through the weephole  400  to the downstream chamber  112 . In some embodiments, a drain  402  may be coupled to the downstream chamber  112  to empty liquid collected therein to an engine crankcase or other external location known to those in the art.  
         [0045]     Referring now to  FIGS. 5 and 6 , liquid pooling in the second area  302  may be reduced by a channel  500  formed to enable liquid access between the access chamber  114  and the upstream chamber  110 . Specifically, the channel  500  may be formed in a lowermost portion of the partition  116  separating the access chamber  114  from the upstream chamber  110 . In one embodiment, the channel  500  substantially corresponds to a bottom edge  502  of the access chamber  114 , thus optimizing drainage of liquid accumulated in the access chamber  114  to the upstream chamber  110 .  
         [0046]     In another embodiment, as best depicted by  FIG. 6 , the channel  500  may direct liquid from the access chamber  114  to a position in the upstream chamber  110  substantially adjacent its bottom edge. As discussed above, the bottom edge of the upstream chamber  110  may substantially correspond to the bottom edge  406  of the divider  108 . Further, the bottom edges of each of the divider  108  and upstream chamber  110  may be substantially arc-shaped such that the channel  500  may cooperate with the weephole  400  to optimize efficient liquid drainage.  
         [0047]     Specifically, liquid accumulated in the access chamber  114  may flow through the channel  500  and exit at a lower corner of the upstream chamber  110 , where the lower corner of the upstream chamber  110  is upwardly disposed from the position of the weephole  400 . The arc-shaped bottom edge of the upstream chamber  110  may then passively urge the liquid towards the weephole  400 , from which it may enter the downstream chamber  112 . In this manner, the channel  500  and weephole  400  combine to efficiently and effectively reduce liquid pooling upstream of the coalescing filter medium  126 .  
         [0048]     In some embodiments, the downstream chamber  112  may comprise a funnel or other design capable of directing the accumulated liquid to a drain  402  coupled thereto. Liquid may be channeled through the drain  402  to an external location or other location known to those in the art.  
         [0049]     The present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.