Diesel exhaust filter construction

A diesel exhaust filter construction includes a rectangular filter block, an elongated non-rectangular jacket with oval cross section, and support structure supporting the filter block in a center of the jacket. The support structure includes shielding components forming an insulating air gap with the jacket around the filter block (including a double-layered air gap in “hot” areas), and further includes support structure slidably supporting one end of the filter block to accommodate dissimilar thermal expansion. The structure further includes baffling components with angled surfaces directing input exhaust gases along efficient flow paths from an inlet cone into front, rear, and opposite sides of the filter block and further directing output exhaust gases from top and bottom sides of the filter block toward a longitudinally-centered outlet cone. Some components are identical is shape and size for use in different locations on the construction, thus simplifying tooling.

BACKGROUND

The present invention relates to diesel exhaust treatment devices for internal combustion engines and the like, and in particular relates to a diesel exhaust filter construction for reducing undesirable emissions, for reducing assembly and component cost, and for increasing operating efficiency of the device.

Modern diesel engines are provided with diesel exhaust treatment devices to reduce environmentally-unfriendly gaseous emissions and particulate emissions. These devices are becoming increasingly complex, both in terms of components and function. An improved diesel exhaust filter construction is desired that uses less components and less costly components, that uses components facilitating assembly and also long term durability, and that assemble to provide optimal handling of the exhaust gases while also providing an efficient flow through and reduced back pressure on exhaust gases coming to the device from a diesel engine.

SUMMARY OF THE PRESENT INVENTION

In one aspect of the present invention, an exhaust filter assembly for filtering particulates from exhaust gases from a diesel engine includes a particulate filter block including a plurality of elements that are adapted to filter the exhaust gases. A jacket is formed around the filter block, the jacket defining an inlet and outlet for directing flow of the exhaust gases into and out of the filter block, respectively. Filter-block-supporting components support the filter block in the jacket, the filter-block-supporting components forming a fixed support and a sliding support that combine to allow dissimilar thermal expansion within the exhaust filter assembly without causing associated mechanical stress.

In another aspect of the present invention, an exhaust filter assembly for filtering exhaust gases from a diesel engine includes a filter block adapted to filter exhaust gases from a diesel engine. A jacket is formed around the filter block, the jacket defining an inlet and outlet for flow of the exhaust gases into and out of the filter block, respectively. A shield subassembly is positioned between the filter block and the jacket that supports the filter block generally in the center of the jacket. The shield subassembly includes first and second shield members that are identical in shape and size and that are positioned to both substantially encapsulate the filter block and also form an air gap with the jacket, the air gap extending fully around a circumference of the filter block and along at least a majority of a length of the filter block.

In yet another aspect of the present invention, an exhaust filter assembly for filtering exhaust gases from a diesel engine includes a filter block including a plurality of elements adapted to filter particles from the exhaust gases of a diesel engine, the filter block defining a rectangular box shape with upstream and downstream ends, right and left sides, and top and bottom sides. At least the upstream and downstream ends include inlet openings for receiving exhaust gases. The top and bottom sides each include at least one outlet opening for emitting filtered exhaust gases. The assembly further includes an elongated non-rectangular jacket subassembly formed around the filter block, the jacket subassembly including an upstream jacket cone defining a circular primary inlet and including a downstream jacket cone defining a circular primary outlet for the exhaust passing through the exhaust filter assembly and further defining a longitudinal direction. An upstream inlet cone supports the filter block and also communicates the exhaust gases from the primary inlet to the inlet openings of the upstream end and that further communicates a portion of the exhaust gases outward along the sides of the filter block to a downstream end of the filter block. A filter end cover directs the portion of exhaust gases into the inlet openings of the downstream end of the filter block. At least one baffle support both supports the filter block and directs the exhaust gases from the outlet openings of the top and bottom sides of the filter block toward the primary outlet. At least the baffle support and the upstream inlet cone include exhaust-directing angled surfaces that extend at an acute angle to the longitudinal direction so that the exhaust gases flowing through the exhaust filter assembly flow with a more uniform flow and with less perpendicular wall structure creating turbulent resistance to flow.

In a narrower aspect, the construction is designed to channel flow into front, rear and two sides of the filter block and out two (top and bottom) side exit holes in the filter block into a core centerline flow, with the supports for the filter block acting as sliding support in at least one area on the filter block to accommodate dissimilar thermal expansion on components.

In yet another aspect of the present invention, an exhaust filter assembly for filtering exhaust gases from a diesel engine includes a filter block adapted to filter exhaust gases from a diesel engine. A jacket is formed around the filter block, the jacket defining an inlet and outlet for flow of the exhaust gases into and out of the filter block, respectively. A shield subassembly is positioned between the filter block and the jacket, the shield subassembly including shield members with embossments that support the shield members away from the jacket to thus form an air gap that extends substantially fully around a circumference of the filter block and along at least a majority of a length of the filter block. Basalt wool insulation is positioned in the air gap and takes up some space in the air gap to further reduce surface temperature.

An object of the present invention is to provide a support structure for sintered metal diesel filter elements and the like, wherein formed channels joined to a filter block of sintered metal sheets position the filter block in an associated jacket to form an insulating air gap. A sliding circular pipe supports the rear mass of the core and allows free thermal expansion of the filter block, while the fixed inlet cone supports the front half mass of the core and reacts to dynamic loads.

Another object of the present invention is to provide a diesel filter element that integrates several functions, so as to reduce the total number of parts in the assembly, simplify their construction, properly channel exhaust gas flow, form an internal heat shield, and support an associated filter block in the jacket in a manner which accommodates free thermal expansion of the core.

Yet another object of the present invention is to provide a diesel filter element that is efficient in use, economical to manufacture, capable of long operating life, and particularly well adapted for the proposed use.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

A diesel exhaust device100(FIGS. 1-3) includes a DOC subassembly101with diesel oxidation catalyst (DOC) for chemically treating diesel exhaust and a diesel particulate filter (DPF) subassembly102adapted to filter particulate from diesel exhaust. The subassemblies use known technologies to accomplish their purposes such that their physical and chemical properties, and also their operating systems, do not need to be described in detail for a person of ordinary skill to understand the present invention. However, the present DPF subassembly102is particularly and inventively constructed to provide advantages as noted below.

The present DPF subassembly102(FIG. 2) includes a rectangular particulate filter block103comprising a plurality of closely-spaced parallel particulate-filtering sintered metal plates sandwiched between a pair of carrier plates, an elongated non-rectangular jacket104with oval cross section, and components forming a support structure for supporting the filter block103generally in a center of the jacket104. As described below, the support structure includes components forming an insulating air gap around the filter block (filled with Basalt wool for improved insulating performance), and further includes support structure slidably supporting one end (i.e., a downstream end) of the filter block to accommodate dissimilar thermal expansion of about 4 to 8 mm (typically about 4.5 to 5 mm) between the filter block103and the jacket104, and still further includes baffling components with angled surfaces directing inflowing exhaust gases from an inlet cone into front, rear, and right/left sides of the filter block and further directing outflowing exhaust gases from a top and bottom of the filter block downstream toward a longitudinally-centered outlet cone. Some components are identical in shape and size for use in different locations on the construction, thus simplifying tooling.

As noted above, the DOC subassemblies are generally known in the art and are commercially available, such that a detailed description of that structure is not required for an understanding of the present invention by a person skilled in this art. The present DOC subassembly101is attached in-line to the DPF subassembly102as illustrated inFIGS. 1 and 7by a clamp106A and gasket that matably join mating configured ends106B and106C.

FIG. 2shows the outer jacket104with mating jacket inlet cone105and jacket outlet cone106. The inlet cone105transitions from a round receiving end to a downstream oval-shaped end (for engaging the jacket104), and the outlet cone106has a shape that provides a reverse transition. The filter block103is shown with a filter inlet cone107(formed by identical top and bottom parts), a downstream filter end cover108, and flow baffles109(only the top one being visible inFIG. 2). The support components include the filter end cover108, which supports a downstream end of the filter block103while permitting exhaust gases to flow from lateral sides of the filter block around and into a downstream end of the filter block103, as described below. The support components also include the baffles109as described below. (SeeFIGS. 4 and 8). The support components also include identical top and bottom shields110and identical side shields111for surrounding the filter block103its full length. The illustrated shields110and111combine to form a “shield subassembly” that extends around a circumference of the filter block103and that extends along a full length of the filter block103. The shields110and111include outwardly projecting channel-shaped embossments causing them to form an air gap to the jacket104that extends circumferentially and longitudinally around the filter block103. By making the top and bottom shield components110and also the side shield components111identical in shape, it saves considerably in their manufacture, since it reduces tooling cost considerably.

The air gap as illustrated is filled by Basalt wool insulation113(FIGS. 7 and 8) for providing a maximum insulating value. Side-located secondary insulation shields114(FIGS. 3 and 8) on an inside of the side shields111form an additional air gap with the jacket104around sides of the filter block103. This additional air gap that helps reduce hot spots on the jacket104along sides of the filter block103which occur due to the directed flow of exhaust gases along the “lateral” flow paths150A (FIG. 4). As noted below, the downstream-extending flange109A of the baffles109also provide an additional air gap117to the shields110at a location that reduces another hot spot on the jacket104. The air gaps combine to form a continuous air gap completely around the filter block103and that extends along a majority of a length of the filter block103, with “double” air gaps in key areas.

Notably, the top and bottom baffles109are identical in shape, and include a longitudinally-extending awning-like portion109A that extends along the jacket104to form a second air gap117(FIG. 7), and also include an angled baffling portion109B that deflects exhaust gases coming out of the (top and bottom) holes153in the filter block103in a desired downstream direction. The baffle109is constructed to support a downstream end of the filter block103in the jacket104/shields110/111. The angled baffling portion109B of the baffle109creates a more uniform flow and reduces turbulence and air drag, and thus in turn reduces resistance to air flow through the device102. Notably, the reduced resistance to air flow through the device102directly contributes to improved gas mileage, since reduced back pressure at the diesel engine exhaust manifold results in engine operating efficiencies. The awning-like portion109A creates an additional air gap to the shields110that reduces a hot spot on the jacket104due to exhaust gas flow coming out of the openings153in the filter block103. The air gaps and Basalt wool insulation minimize the skin temperature of the DPF device102and hence minimize heat loss. The baffles109combine with adjacent components to prevent the lateral flow of exhaust gases from bypassing the filter block103. Thus, the baffles109force the lateral flow into the end cover108, which in turn directs the lateral flow into a downstream end of the filter block103.

The upstream end of the filter block103is supported by a fixed support system at location118. The downstream end of the filter block103is slidably supported by a slip-permitting support at location119, which is formed in part by a liner end cone120. It is contemplated that additional supports could be added as needed to support the filter block103in a center of the oval-shaped jacket104. The fixed support system at location118is provided by the filter inlet cone107, which includes an upstream flange165on the filter inlet cone107fixedly connected to upstream flanges166and167on the jacket inlet cone105and on the shields110/111, respectively, and also includes a downstream flange168on the filter inlet cone107fixedly connected to a top and bottom edges of an upstream end of the filter block103. Notably, the filter inlet cone107permits exhaust gases to flow laterally around right and left edges of the front end. The sliding support location119is provided by the (downstream) liner end cone120, which includes a downstream flange169on the liner end cone120slidably engaging the flange170on the outlet tube154A (which is supported by the flange171on the outlet cone106). Note the gap172between the liner end cone120and the outlet cone106which permits the dissimilar thermal expansion of the inner components relative to the jacket104of about 4 to 8 mm longitudinally, or more typically about 4.5 to 5 mm longitudinally. Notably, the above structure provides support to the filter block103, as well as fixed support at one end and sliding support at the other end of the filter block103. The support for the downstream end of the filter block103is provided by the baffles109, and by the end cover108.

Several components include angled gas-baffling portions, such as the components107,108,109, and120, which include angled baffling portions107A,108A,109B,120A (FIGS. 3 and 4) with angled surfaces. The angled gas-baffling portions extend at a non-perpendicular angle relative to a longitudinal direction defined by the jacket104. Their specific angle can be varied, depending on the overall spatial dimensions required for the device102, and depending on the overall functional requirements of the device102, such as gas-volume-handling requirements, back pressure requirements, residue-holding requirements, and the like. The angled surfaces are designed to deflect exhaust gases in a manner creating an optimal gas flow with minimal air turbulence and back pressure, thus reducing back pressure on exhaust gases coming from the engine. Notably, walls in a DPF device that are perpendicular to exhaust gas flow will tend to create a more inefficient flow of the exhaust gases . . . which leads to higher air back pressures. At the same time, incorporating angled wall portions can lead to a difficult assembly and more expensive components, thus making their design a challenging task. Accordingly, the angled wall portions of the present design are believed to be innovative, and they are believed to provide surprising and unexpected results in terms of their construction, assembly, and function.

The present inventive components and their assembly combine to define multiple sealed air passages that lead through different areas of the filter block103. SeeFIG. 4which shows a first gas flow path being straight into an upstream end of the filter block and out top and bottom openings of the filter block toward the downstream outlet, and which also shows a second path extending from the inlet laterally to sides of the filter block and into a rear end of the filter block and then out the top and bottom openings of the filter block toward the downstream outlet. The exhaust gases are divided into various streams as they are forced to travel along one of the predetermined paths through the device102(seeFIG. 4). These angled baffling portions direct the flow of exhaust gases to provide the benefits listed above. Another benefit of the present components and baffles is that the exhaust gases flow through a larger percentage of the filter block103, such that the filter block103is used more efficiently. For example, as one area of the filter block103becomes nearly “plugged,” the exhaust gases are forced toward other areas. This results in a more efficient and longer lasting use of the filter block103, and further reduces the time between soot regenerations. Persons skilled in this art will understand that soot regeneration is where the filter block103becomes filled with soot and undergoes a heat cycle where the carbon and other combustibles are “burned off.” This leaves a residue of unburnable material called “ash.” The present device102is constructed with large deposit-receiving areas below and around the filter block103, and further includes passages extending around the deposit-receiving areas, thus making the present device longer lasting because it can hold a larger amount of unburnable residue before the DPF device102becomes overfilled and requires maintenance for efficient operation. It is significant that the present device102provides several (non-blocked) pathways for the exhaust gases to flow through the device102, which provides for alternative exhaust gas flow even when the unburnable residue builds up.

The flow of exhaust gases (seeFIG. 4for flow, andFIG. 3for some features) includes two flow streams150and151(FIG. 4) which pass from the DOC subassembly101into the inlet opening152of the DPF subassembly102. The filter inlet cone107allows the incoming exhaust gases of stream150to pass directly longitudinally into the upstream end of the filter block103, and then to flow along divided flows150A and150B out top and bottom outlet ports153in the filter block103. The baffles109direct the flows150A and150B toward the outlet opening154in an outlet tube154A of the subassembly102. The flow151divides into lateral flows as it encounters a front of the filter block103, and as a result it flows laterally (sideways) out the right and left wings155of the inlet cone107to locations155A (FIG. 6) adjacent the sides of the filter block103. The flow151travels along the filter block103, and then either enters a side156of the filter block103, or alternatively it flows to the filter end cover108. The filter end cover108receives the lateral flows and directs the flows in a reverse direction157into the downstream end of the filter block103. A top portion151A of the divided flow151joins with the flow150A to exit the top outlet port153, and a bottom portion151B of the divided flow151joins with the flow150B to exit the bottom outlet port153. The baffles109direct the combined flows out the outlet opening154as noted above. Notably, as the filter block103fills with non-burnable residue, the flow150reduces, causing the flow151to increase. Also, the flows are affected by the regeneration cycles of the device102for burning off carbon and other burnable materials captured in the filter block103. This is monitored in part by a temperature sensor (see right end ofFIG. 1, or left upper corner ofFIG. 6) which is connected to a vehicle control emission system.

A unique feature of the present device102is the canning of a rectangular metal filter block into an oval section. Common designs of filters are all cylindrical with uni-axial flow in/out. This design channels flow in four sides and out two exit holes. This is accomplished by adding the inlet cone half-shell105which changes section and shape as previously described and the outlet cone106which joins the two exit flows into one centerline flow through a sliding pipe support of the core.