Related Applications

This application claims the benefit of U.S. Provisional Application No. 61/731 ,207 filed November 29, 2012, which is hereby incorporated herein by reference.

Field of Invention

The present invention relates generally to engine assemblies including an internal combustion engine , and more particularly to engine assemblies also including an exhaust gas recycling system with a gas/solid separator.

Background

Exhaust gas recycling systems are used for consumer and commercial products, such as in engine assemblies for diesel trucks or for railway vehicles, such as locomotives. The engine assemblies are often equipped with an internal combustion engine fluidly connected to an exhaust gas recycling system. The exhaust gas recycling system often includes an inertial air separator having convoluted passages, filtering elements, and/or pressure regulation for controlling the quality and quantity of exhaust gas reentering the internal combustion engine after initial expulsion. Exhaust gas typically includes carbon soot from unburnt fuel, and can also include foreign particulate such as particulate from wear components, non-wear components, mineral scale, or other deposits that have broken free. The carbon soot is recycled back into the internal combustion engine because it can be burned in combustion, while the other materials, such as metallic particulate, can instead severely damage the internal combustion engine. A common method of separating the particulate from gas, and also low density particulate, such as carbon soot, from high density particulate, such as metallic particulate, is mechanical sieving or filtering. Mechanical sieving is limited in its use, however, because soot or other particulate will build up and clog the filter, causing the mechanical sieve exhaust gas recycling system to become inoperable.

Summary of Invention

The present invention provides an inertial air separator for exhaust gas recycling systems that uses inertial forces instead of mechanical sieving to scrub exhaust gas being recycled into internal combustion engines of engine

assemblies, such as internal combustion engines of diesel engine assemblies. The inertial air separator scrubs or separates high density particulate, such as metallic particulate, from exhaust gas exiting an internal combustion engine, thereby allowing gas and low density particulate, such as carbon soot, to be reintroduced into the internal combustion engine for continued combustion. The inertial air separator includes a housing, a blade pack disposed in the housing, a divider arranged between the housing and the blade pack, and a particle trap area defined between the divider and the housing for receiving particulate.

According to one aspect of the invention, an inertial air separator, for separating particulates in an airflow, includes a housing having an inlet port located at an inlet end, an outlet port located at an outlet end, and an incoming flow path defined therebetween. The inertial air separator also includes a blade pack for directing airflow entering the inlet port along a periphery of the blade pack, and the blade pack includes axially spaced-apart blades defining

convoluted flow paths therebetween. The inertial air separator further includes a divider arranged between the housing and the blade pack for creating a recirculation flow path radially outwardly spaced from the incoming flow path and a particle trap area defined between the inner divider and the housing for receiving particulate.

The inertial air separator may further include a flow restriction in the recirculation flow path downstream of the particle trap area. The inertial air separator may further include a deflector radially spaced between the divider and the housing for preventing particulate in the particle trap area from reentering the recirculation flow path. The particle trap area may be at least partially defined by the deflector. Downstream of the particle trap area the recirculation flow path may include a reduced area section with respect to the incoming flow path.

The divider may be spaced from the inlet end so as to direct airflow from the recirculation flow path back into the incoming flow path. The divider may be axially spaced from the inlet and outlet ends of the housing, thereby allowing for flow around the divider between the inlet and outlet ends.

The blades of the blade pack may be arranged about a center longitudinal axis of the inertial air separator. The blades of the blade pack may be concentrically arranged about a common axis. The blades of the blade pack may be arranged about a curved common axis. A leading blade in the pack may have a curved configuration with a curved end of the leading blade oriented towards the inlet end of the housing. A trailing blade in the pack may be sealed around its periphery at its downstream end against the outlet end of the housing.

The axially spaced-apart blades may include annular blades defining radially inwardly therein a central passage opening to the outlet port. The axially spaced-apart blades may include frustoconical blades increasing in diameter from their upstream ends to their downstream ends. The axially spaced-apart blades may include cup-shaped blades having their closed ends oriented towards the inlet end of the housing.

The divider may have an annular configuration. The inertial air separator may further include a magnet spaced adjacent the particle trap area for attracting particulate into the particle trap area. The particle trap area may be disposed adjacent the inlet end of the housing.

The axially spaced-apart blades may be substantially equally spaced- apart. The blade pack may be aligned to direct airflow exiting the blade pack along axes substantially parallel to a central longitudinal axis of the outlet port.

According to another aspect of the invention, an inertial air separator includes a housing having an inlet located at an upstream end and an outlet located at a downstream end. The inertial air separator also includes a blade pack including an arrangement of blades arranged in stacked relation within the housing, the arrangement of blades defining flow gaps between adjacent blades in the pack, and a peripheral gap located between the blade pack and the housing, wherein a leading blade in the blade pack has a curved configuration with a curved end of the leading blade oriented towards the upstream end of the housing, wherein a trailing blade in the blade pack is sealed around its periphery at its downstream end against the downstream end of the housing, and whereby airflow entering through the inlet of the housing is directed around a periphery of the blade pack, inward through the flow gaps between adjacent blades, and then to the outlet of the housing. The inertial air separator further includes a particle trap area defined between the housing and the blade pack, whereby heavy particles in the airflow are separated out of flow when the airflow passes inwardly through the adjacent blades and settles out in the particle trap area.

The inertial air separator may further include a divider spaced between the blade pack and the housing for directing airflow not passing inwardly through the adjacent blades across the particle trap area. The inertial air separator may further include a flow restriction downstream of the particle trap area. The inertial air separator may further include a deflector radially spaced between the divider and the housing for preventing particulate in the particle trap area from reentering the airflow. The particle trap area may be at least partially defined by the deflector. The in particle trap area may be disposed downstream of the outlet.

The divider may be spaced from the upstream end so as to direct airflow about the divider and back into flow with airflow entering the inertial air separator through the inlet. The divider may be axially spaced from the inlet and outlet ends of the housing, thereby allowing for flow around the divider between the inlet and outlet ends.

The blades of the blade pack may be arranged about a center longitudinal axis of the inertial air separator. The blades of the blade pack may be

concentrically arranged about a common axis. The blades of the blade pack may be arranged about a curved common axis. The blades may include annular blades defining radially inwardly therein a central passage opening to the downstream outlet. The blades may include frustoconical blades increasing in diameter from their upstream ends to their downstream ends. The blades may include cup-shaped blades having their closed ends oriented towards the upstream end of the housing.

The inertial air separator may further include a magnet spaced adjacent the particle trap area for attracting particulate into the particle trap area. The particle trap area may be disposed adjacent the upstream end of the housing.

The blades may be substantially equally axially spaced-apart. The blade pack may be aligned to direct airflow exiting the blade pack along axes substantially parallel to a central longitudinal axis of the outlet.

According to yet another aspect of the invention, an inertial air separator includes an inlet port for receiving airflow, an outlet port for exhausting airflow, and a central flow chamber disposed between the inlet port and outlet port, wherein an initial flow path extends between the inlet port and outlet port in the central flow chamber. The inertial air separator also includes a blade pack arranged in the central flow chamber, the blade pack including blades defining winding airflow passages therebetween for directing airflow towards the outlet port. The inertial air separator further includes a divider mounted in the central flow chamber and located for directing airflow not entering the winding airflow passages about the divider, wherein the divider forms a restricted flow path with respect to the initial flow path through the central chamber, thereby causing particulate to fall out of airflow moving about the divider. The inertial air separator also includes a particle trap area for collecting the particulate falling out of the airflow, the particle trap area located upstream of the outlet port.

The inertial air separator may further include a magnet spaced adjacent the particle trap area for attracting particulate into the particle trap area.

According to yet another aspect of the invention, a method for separating particulate in an airflow includes the steps of directing incoming contaminated airflow through a blade pack through which the airflow passes through a tortuous path for causing heavy particulate to remain in the airflow while allowing airflow with fewer heavy particulates to pass through to an outlet, directing incoming contaminated airflow not passing through the blade pack across a collection chamber isolated from the blade pack for collecting heavy particulate falling out of the airflow, and routing the airflow passing the collection chamber back into flow with the incoming contaminated airflow.

The method may further includes the step of directing airflow passing the collection chamber through a restricted area path with respect to the area of an incoming flow path extending through an inlet towards the blade pack.

Brief Description of the Drawings

Fig. 1 is a schematic illustration of an exemplary engine assembly equipped with an exemplary inertial air separator according to the invention.

Fig. 2 is a perspective view of the exemplary inertial air separator of Fig.

1 .

Fig. 3 is a cross-sectional view of the exemplary inertial air separator of

Fig. 1 . Fig. 4 is a cross-sectional view of another exemplary inertial air separator. Fig. 5 is a schematic illustration of another exemplary engine assembly equipped with another exemplary inertial air separator according to the invention.

Fig. 6 is a perspective view of the exemplary inertial air separator of Fig. 5.

Fig. 7 is a side view of the exemplary inertial air separator of Fig. 5.

Fig. 8 is a top view of the exemplary inertial air separator of Fig. 5.

Fig. 9 is a view of the inlet end of the exemplary inertial air separator of

Fig. 5.

Fig. 10 is a view of the outlet end of the exemplary inertial air separator of

Fig. 5.

Fig. 1 1 is a cross-sectional view of the exemplary inertial air separator of

Fig. 5.

Fig. 12 is a cross-sectional view of yet another exemplary inertial air separator.

Fig. 13 is a cross-sectional view of still another exemplary inertial air separator.

Detailed Description

The principles of the present application have general application to engine assemblies including an internal combustion engine, and particular application to engine assemblies further including an exhaust gas recycling system having an exhaust gas recycling inertial air separator, and thus will be described below chiefly in this context. The inertial air separator may be suitable for use in exhaust gas recycling systems of railway vehicles, such as

locomotives, or of trucks, construction equipment, etc. It will of course be appreciated, and also understood, that the principles of the invention may be useful in other filtering assemblies, in other exhaust applications including non- diesel engines or where reduction in exhaust emissions is desired, or in non- exhaust applications such as intake air for combustion, process air for cooling or manufacturing needs, HVAC, etc.

Referring now to the drawings in detail, and initially to Fig. 1 , an

exemplary exhaust gas recycling (EGR) inertial air separator 10, herein also referred to as an EGR inertial air filter or an EGR inertial fluid separator, is illustrated in combination with an engine assembly 12 including numerous other assembly components. The inertial air separator 10 is fluidly connected between an EGR cooler 13 and an EGR mixer 15. An internal combustion engine 14 is fluidly connected between the EGR mixer 15 and an EGR valve 16, and the EGR valve 16 is subsequently fluidly connected to the EGR cooler 13. It will herein be understood that fluid connection or communication may include gaseous or liquid connection or communication or any combination thereof. The assembly components may be fluidly connected to one another via passages, such as tubes, which may be coupled to the assembly components by couplings, such as annular couplings.

As shown, initial exhaust gas 17 exhausted from the internal combustion engine 14 is directed to the EGR valve 16. The EGR valve 16 may exhaust a portion of exhaust gas 18 to atmosphere and may direct another portion of exhaust gas 19 into the EGR cooler 13. The EGR cooler 13 cools airflow exhausted from the internal combustion engine 14 before the airflow enters the inertial air separator 10. The inertial air separator 10 allows for removal of dense particulate, such as mineral scale, deposits, or heavy metallic particulate from wear or failure parts, from the airflow reentering the internal combustion engine 14. In this way lighter particulate, such as soot, is enabled to remain in the airflow for being combusted in the internal combustion engine 14. As shown, the inertial air separator 10 is fluidly connected at its inlet end 20, also herein referred to as an upstream end, to the EGR cooler 13. At its outlet end 26, also herein referred to as a downstream end, the inertial air separator 10 is fluidly connected to the EGR mixer 15. The EGR mixer 15 mixes airflow exiting the inertial air separator 10 with external airflow 15, such as from atmosphere, before the airflow reenters the internal combustion engine 14. It will herein be understood that airflow may include fluid, such as gas, liquid, or a combination of the two, in addition to particulate carried by the fluid. The airflow may also include clean external air introduced into flow with the contaminated airflow by the EGR mixer 15, or by other assembly components not shown. It will also herein be understood that the assembly components may be arranged or fluidly connected in any other suitable arrangement. For example, the EGR cooler 13 may be instead fluidly connected between the inertial air separator 10 and the EGR mixer 15, or the EGR mixer 15 may be instead fluidly connected between the EGR cooler 13 and the inertial air separator 10.

Turning to Fig. 2, the exemplary inertial air separator 10 is shown apart from the engine assembly 12 and includes a housing 34, preferably substantially cylindrical, that extends between the inlet end 20 and the outlet end 26.

Alternatively, the housing 34 may have a frustoconical or conical shape. The housing 34 is open at the inlet end 20 at an inlet port 36, herein also referred to as a flow inlet, and is likewise open at the outlet end 26 at an outlet port 40, also herein also referred to as a flow outlet. Auxiliary couplings 42, 44 are located adjacent each of the inlet and outlet ports 36, 40 for providing additional access to flow through the housing 34. For example, gas or pressure sensors may be mounted at the auxiliary couplings 42, 44. A magnetic field inducing element, such as a magnet 46, to be discussed further, is coupled to the housing 34 at the inlet end 20 or upstream end for attracting metallic particulate out of the airflow passing through the inertial air separator 10.

Turning next to Fig. 3, the inertial air separator 10 includes a central chamber 50 defined by the housing 34 and disposed between the inlet and outlet ports 36, 40. A blade pack 52, also herein referred to as a louver set, is disposed within the central chamber 50 and is axially aligned between the inlet and outlet ports 36, 40. A peripheral gap 54 is defined between a periphery 56 of the blade pack 52 and the housing 34. The blade pack 52 has a substantially conical shape, and increases in diameter across its length from its upstream end 60 to its downstream end 62. Alternatively, the blade pack 52 may have a substantially cylindrical shape, and thus the may not increase in length between its upstream and downstream ends.

The blade pack 52 includes a plurality of blades 64, also herein referred to as vanes or louvers, which are arranged, preferably concentrically, about a center longitudinal axis 66 of the housing 34. With respect to positioning from the upstream end 60 to the downstream end 62 of the blade pack 52, each blade positioned successively closer to the downstream end 62 may have a greater outer diameter than the previous blade positioned successively closer to the upstream end 60. In this way, the blade pack 52 has the substantially conical shape. Alternatively, the blades 64 may instead each have substantially the same outer diameter, and thus the blade pack 52 may have a substantially cylindrical shape.

The blades 64 are mounted in the housing 34 via a system of supports. Two longitudinal supports 70, 72 mounted to the outlet end 26 of the housing 34 extend substantially longitudinally along a portion of each of the blades 64 for supporting the blades 64. The blades 64 may be attached to the longitudinal supports 70, 72 via additional mechanical couplers, welding, lateral supports attached to the longitudinal supports, or via other suitable attachment methods. Any suitable number of longitudinal supports 70, 72 may also be utilized, and/or the supports 70, 72 may be attached to the inlet end 20 of the housing 34. It will also be appreciated that any suitable number of blades 64 may be included in the blade pack 52. Also, the blades 64 may be concentrically arranged about another common axis, and the common axis may be a curved axis rather than a straight axis.

The blades 64 are provided in stacked or nested relation so as to be axially-spaced from one another, preferably equally, via their attachment in relation to the longitudinal supports 70, 72. As compared to a mechanical sieve, having gaps sized smaller than particulate dimensions, the spacing between the blades 64 may be greater than the largest dimension of particulate, such as metallic particulate, being separated from the airflow through the inertial air separator 10. Instead, equal spacing allows for efficient control of airflow through the blade pack 52 and of separation of particulate from the airflow by controlling the density or weight of particulate that is able or unable to traverse the flow paths through the blade pack 52, to be discussed further.

The blades 64 include a leading blade 74 at the upstream end 60 of the blade pack 52, a trailing blade 76 at the downstream end 62 of the blade pack 52, and intermediary blades 78 spaced therebetween. Airflow entering the housing 34 via the inlet port 36 is first directed along an incoming flow path 80 towards the leading blade 74 of the blade pack 52. The incoming flow path 80 extends from the inlet port 36 and then towards and around the periphery 56 of the blade pack 52 into the peripheral gap 54. The leading blade 74 has a curved configuration, such as a cup-shaped configuration, for deflecting airflow of the incoming flow path 80 that has entered the housing 34 via the inlet port 36. The leading blade 74 has a closed end 82 oriented towards the inlet end 20 of the housing 34 and an open end 84 opening towards the outlet end 26 of the housing 34. The trailing blade 76 in the pack is sealed around its periphery 86 at its downstream end 90 against the outlet end 26 of the housing 34.

The intermediary blades 78 between the leading and trailing blades 74,

76, and also the trailing blade 76, are annular thereby defining a central cavity 94, also herein referred to as a central passage, disposed radially inwardly of the periphery 56 of the blade pack 52. The central cavity 94 is open to the outlet port 40 and is separated from the incoming flow path 80 via the blade pack 52. More particularly, the intermediary and trailing blades 78, 76 have a frustoconical shape with the downstream ends 96 of the intermediary blades 78 having larger diameters than the upstream ends 100, and the trailing blade 76 being likewise configured. The leading, trailing, and intermediary blades 74, 76, 78 are radially outwardly angled towards the outlet end 26 of the housing 34 to define tortuous, winding, paths or passages, such as convoluted flow gaps 96, between adjacent blades 64 in the blade pack 52. The flow gaps 96 provide for fluid

communication between the peripheral gap 54 and the central cavity 94.

Surrounding the blade pack 52 is an annular divider 100. The divider 100 is spaced radially inwardly from the housing 34 and radially outwardly from the blade pack 52. The divider 100 and housing 34 define a bypass or recirculation flow path 102 therebetween. The recirculation flow path 102 is thereby separated from the incoming flow path 80 entering the central chamber 50 of the housing 34 through the inlet port 36. The divider 100 is mounted in the housing 34 via a lateral support 104 extending between the housing 34 and the divider 100. The lateral support 104 includes a substantially thin lateral cross-section so as to not interfere with airflow through the recirculation flow path 102. The divider 100 is axially-spaced from each of the inlet and outlet ends 20, 26 of the housing 34 to enable airflow to move around the full axial length of the divider 100 between the inlet and outlet ends 20, 26. It will be appreciated that any suitable number of lateral supports 104 or a suitable alternative support mechanism may be utilized.

An annular outer barrier 106 is spaced radially outward of the divider 100, such as between the divider 100 and the housing 34, and an annular inner barrier 1 10 is spaced radially inward of the divider 100, such as between the divider 100 and the blade pack 52. As shown, the outer and inner barriers 106, 1 10 may share a common central axis with the divider 100 and the blade pack 52. Alternatively, the barriers 106, 1 10 may have other suitable common central axes or different central axes with respect to one another. Each of the inner and outer barriers 1 10, 106 extends axially outwardly from the inlet end 20 of the housing 34. In this manner, arrangement of the blade pack 52, divider 100, inner barrier 1 10, and outer barrier 106 is substantially axisymmetric about the center longitudinal axis 66. One of ordinary skill in the art will also appreciate that the divider 100 and barriers 106, 1 10 may be of another suitable shape and may not surround the blade pack 52 or extend fully circumferentially about an interior of the housing 34. Rather, the divider 100 and barriers 106, 1 10 may extend only partially about the blade pack 52 and may be located only in a lower portion 1 14 of the central chamber 50. Such an alternative configuration may be suitable particularly if the central longitudinal axis 66 of the housing 34 is aligned substantially horizontally, allowing for dense particulate to move gravitationally towards the lower portion 1 14.

The arrangement of the inner and outer barriers 1 10, 106 and the divider 100 provides for a winding, restricted flow path portion 1 16 of the recirculation flow path 102. The restricted flow path portion 1 16 is disposed at the inlet end 20 of the housing 34 and is defined between the outer barrier 106, divider 100, and inner barrier 1 10. The restricted flow path portion 1 16 has a reduced area as compared to the area of the incoming flow path 80 through the portion of the central chamber 50 that is located radially inward of the divider 100. The reduced area in combination with the winding nature of the restricted flow path portion 1 16 causes airflow moving through the restricted portion 1 16 to have a higher velocity as compared to airflow moving through other flow paths, such as the incoming flow path 80. Further, airflow at an inlet 120 of the restricted portion 1 16 may have a greater pressure than airflow at an outlet 122 of the restricted portion 1 16, thus causing a Venturi effect. Accordingly the restricted flow path portion 1 16 is configured to cause scavenger bleed or removal of particulate from the airflow. More particularly, the configuration of the restricted portion 1 16 prevents dense particulate from traversing the shape of the restricted portion 1 16 or from gaining substantial inertia for traversing the restricted portion 1 16, thereby causing the dense particulate to fall out of airflow in the

recirculation flow path 102 prior to the restricted portion 1 16.

A particle trap area 124, also herein referred to as a collection reservoir, for collecting this dense particulate is located adjacent the restricted flow path portion 1 16, such as upstream of the restricted flow path portion 1 16. The particle trap area 124 serves as collection chamber for dense particulate falling out of airflow moving towards and through the restricted flow path portion 1 16 due to the winding nature of the restricted portion 1 16 and also due to the change in velocity and pressure of airflow moving through the restricted portion 1 16. The particle trap area 124 is isolated from the blade pack 52 and from the convoluted flow gaps 96 defined therein by the divider 100. As shown, the particle trap area 124 is annular and is disposed at the inlet end 20 of the housing 34 where it is defined by both the housing 34 and the outer barrier 106. The outer barrier 106 serves as a deflector for minimizing turbulence of airflow moving across and into the particle trap area 124 and for preventing

reentrainment of particulate in the particle trap area 124 back into the airflow in the recirculation flow path 102.

It will of course be appreciated that the particle trap area 124 may be of any suitable shape. The outer barrier 106 also may not be present. In such case, the restricted flow path portion 1 16 may be defined only by the divider 100 and the inner barrier 1 10, and the particle trap area 124 may instead be defined by the housing 34 and the divider 100 and/or the inner barrier 1 10. The housing 34 may also include an access panel (not shown) located adjacent the particle trap area 124 for enabling emptying of the particle trap area 124. Such panel may be removable from the housing 34, hinged to the housing 34, or attached via other suitable mechanical coupling.

A magnetic field inducing element, such as the magnet 46, may also be coupled to the housing 34, such as adjacent the particle trap area 124.

Alternatively, the magnet 46 may extend through the housing 34 to at least partially define the particle trap area 124. As shown, the magnet 46 is coupled to the inlet end 20 of the housing 34 and partially defines a lower portion 126 of the annular particle trap area 124. The magnet 46 may provide for attraction of metallic particulate, thus causing metallic particulate in the airflow in the recirculation flow path 102 to fall out of the airflow and into the particle trap area 124. Any suitable number of magnets 46 may be utilized and may be positioned or spaced at a location or locations of the housing 34 suitable for causing particulate to fall out of airflow and into the particle trap area 124.

Accordingly, the spacing of the blade pack 52, divider 100, and inner and outer barriers 1 10, 106 in relation to one another provide for separation of dense particulate from lighter particulate that has entered the incoming flow path 80 of the inertial air separator 10 through the inlet port 36 of the housing 34.

Generally, substantially all of the contaminated incoming airflow, including the particulate, is directed along the incoming flow path 80. As this contaminated airflow moves along the incoming flow path 80 it may impact upon the closed end 80 of the leading blade 74 of the blade pack 52 and/or be directed about the periphery 56 of the blade pack 52. Lighter, less dense particulate and the airflow carrying it, and also airflow having fewer heavier, dense particulates, is then directed through the convoluted flow paths 96 between the blades 64 of the blade pack 52. Airflow having a larger quantity of heavier, denser particulate is directed towards the particle trap area 124.

More particularly, the lighter particulate and the airflow carrying it is separated from the incoming flow path 80 and is directed into the convoluted flow gaps 96, through the central cavity 94, and out of the housing 34 via the outlet port 40. The arrangement and shape of the blades 64 of the blade pack 52 allow for this separation. Due to its greater density and/or weight causing increased inertia as compared to soot, and also due to the winding nature of the convoluted flow gaps 96, the metallic and other non-soot particulate will be unable to remain in the airflow being directed into the central cavity 94. Thus, airflow containing dense particulate, such as metallic particulate, is separated from airflow containing less dense particulate, such as soot. Airflow containing the less dense particulate is able to enter the convoluted flow gaps 96 between the blades 64 of the blade pack 52.

Consequently, the dense particulate and airflow not entering the flow gaps 96 is directed along the periphery 56 of the blade pack 52 towards the closed annular portion 130 of the outlet end 26 of the housing 34, which is located radially outward of the trailing blade 76. This dense particulate is then directed around the upstream end 132 of the divider 100 and into the recirculation flow path 102 defined between the divider 100 and the housing 34. The dense particulate, and the airflow carrying it, that has entered the recirculation flow path 102 is then directed further along the recirculation flow path 102 and towards the restricted flow path portion 1 16. Due to the winding nature, reduced area, and increased airflow velocity through the restricted flow path portion 1 16, the dense particulate is substantially unable to traverse the restricted portion 1 16. The dense particulate instead is caused to fall out into the particle trap area 124 disposed upstream of the restricted portion 1 16. Airflow moving through the restricted portion 1 16 is then directed around the downstream end 134 of the divider 100 and back into flow with the contaminated airflow moving through the incoming flow path 74. Dense particulate not falling out of the airflow during its first pass of the particle trap area 124 may again be directed along the periphery 56 of the blade pack 52, around the divider 100, and towards the particle trap area 124. Airflow no longer containing large quantity of dense particulate may traverse the convoluted flow gaps 96 and move towards the outlet port 40. In this manner, the inertial air separator 10 provides for internal recirculation of the airflow entering the separator 10, and thus allows for more efficient and thorough separation of dense particulate from the airflow.

Referring now to Fig. 4, another exemplary inertial air separator for use with the engine assembly 12 is shown at 140. The inertial air separator 140 may be used in place of the inertial air separator 10, and the discussion of the inertial air separator 140 may omit many features of the inertial air separator 140 that are similar to those of the inertial air separator 10. In addition, features of the inertial air separator 140 may be combined with those of the inertial air separator 10. In contrast with the inertial air separator 10, the inertial air separator 140 includes a substantially frustoconical housing 144 and a substantially cylindrical blade pack 152. The housing 144 decreases in diameter from an inlet end 160 to an outlet end 162 of the inertial air separator 140. The blades 164 of the blade pack 152 are concentrically arranged about a central longitudinal axis 166 of the housing 144 and each have substantially equal outer diameters. The housing 144 and blade pack 152 are configured to provide a successively decreasing area between the housing 144 and the blade pack 152 in a direction from the inlet end 160 to the outlet end 162. In this way, the inertial air separator 140 provides similar flow characteristics as compared with the inertial air separator 10 having the substantially cylindrical housing 34 and substantially conical blade pack 52, which are likewise configured to provide a successively decreasing area between the housing 34 and the blade pack 52 in a direction from the inlet end 20 to the outlet end 26.

Turning now to Fig. 5, another exemplary engine assembly is shown at 212 and includes another exemplary exhaust gas recycling inertial air separator, shown at 210. The inertial air separator 210 is fluidly connected between an internal combustion engine 214 and an EGR mixer 216. The inertial air separator 210 may be used in place of the inertial air separators 10 and 140, and the discussion below omits many features of the inertial air separator 210 that are similar to those of the inertial air separators 10 and 140. In addition, features of the inertial air separator 210 may be combined with those of the inertial air separators 10 and 140.

Turning to Figs. 6-1 1 , the exemplary inertial air separator 210 is shown apart from the engine assembly 212 and includes a housing 218 extending between an inlet end 220 and an outlet end 226. The housing 218 includes a substantially cylindrical upper portion 228 and a substantially trapezoidal lower portion 230, although any other suitable shape may be utilized. The inertial air separator 210 also includes a central chamber 234 defined by the housing 218 and disposed between inlet and outlet ports 236, 238 in the housing 218.

As best shown in Fig. 1 1 , a blade pack 252 is disposed within the central chamber 234 and extends between an upper housing surface 254 and a lower housing surface 256. An incoming flow path 260 of the inertial air separator 210 extends from the inlet port 236 to the blade pack 252. A central longitudinal axis 262 of the blade pack 252 is aligned in an angled orientation with respect to a central longitudinal axis 264 of the housing 218 extending between the inlet and outlet ports 236, 238. The central axis 262 of the blade pack 252 is a

substantially straight axis, though the central axis 262 may be curved.

Additionally, other suitable alignments of the blade pack 252 in respect to the housing 218 and to the central axis 264 of the housing 218 may be used. The blade pack 252 includes a plurality of curved laterally-extending blades 266 arranged in stacked orientation with respect to one another. The curved blades 266 have a curved V-shape cross-section defined by a curved center portion 270 and upstream and downstream elements 272, 274 extending therefrom. Particularly, each blade 266 has a closed, convex upstream end 276 oriented towards the inlet end 220 of the housing 218 and an open, concave downstream end 280 oriented towards the outlet end 226 of the housing 218. The blades 266 are axially spaced from one another, preferably equally, via their attachment to longitudinal supports 282, 284 mounted to the housing.

As shown, each blade 266 extends the full lateral length of the central chamber 234, preventing airflow from moving between lateral ends of the blade pack 252 and sides 288 (Fig. 6) of the housing 218. The blade pack 252 partially divides the central chamber 234 into a lower peripheral gap 290 and an upper peripheral gap 292. The lower peripheral gap 290 is defined between a lower periphery 294 of the blade pack 252 and a divider 300, to be discussed further. The upper peripheral gap 292 is defined between an upper periphery 296 of the blade pack 252 and the upper housing surface 254. An upper reduced area gap portion 302 may be defined between a leading blade 304 of the blade pack 252 and the upper housing surface 254. The upper reduced area gap portion 302 may have a reduced area as compared to the areas of the upper and lower peripheral gaps 290, 292. A trailing blade 306 in the pack is sealed around its periphery 310 at its downstream end 312 against the outlet end 226 of the housing 218. An incoming flow path 313 extends between the inlet port 236 and the blade pack 252.

It should be noted that the leading blade 304 may be in contact with the upper housing surface 254, thereby preventing airflow from moving about an upstream end 314 of the leading blade 304 between the upper and lower peripheral gaps 290, 292. The trailing blade 306 may also be mounted on the longitudinal supports 282, 284 so as to be spaced from the housing 218 to define a lower reduced area gap portion (not shown), thereby allowing airflow around the downstream end 316 of the blade pack 252. One of ordinary skill will also realize that the blades 266 may be laterally spaced from the sides 288 of the housing 218 in the same manner. The blades 266 of the blade pack 252 are axially aligned to define a plurality of convoluted flow gaps 320 between adjacent blades 266 of the blade pack 252. The flow gaps 320 provide for fluid communication between the lower peripheral gap 290 and the upper peripheral gap 292. The alignment of the blades 266 in relation to one another, and the configuration of each of the separate blades 266, provides for airflow exiting the convoluted flow gaps 320 to be directed towards the outlet port 238 along axes 324 that are substantially parallel to a central longitudinal axis 326 of the outlet port 238. It will be appreciated that the central axis 326 of the outlet port 238 may be collinear with the central axis 264 of the housing 218. To direct the airflow exiting the convoluted flow gaps 320, the downstream element 274 of each of the blades 266 may be aligned substantially parallel with a transverse plane 330 (Fig. 6) of the inertial air separator 210.

Mounted in a lower portion 332 of the central chamber 234 is the divider 300, extending between the inlet and outlet ends 220, 226 of the housing 218. The divider 300 is spaced from each of the blade pack 252 and the lower portion of the housing 230. The divider 300 is also longitudinally-spaced from each of the inlet end 220 and outlet end 226 of the housing 218 to provide for airflow around the divider 300. Defined between the divider 300 and the lower portion of the housing 230 is a recirculation flow path 334. A downstream end 336 of the divider 300 may be configured, such as curved, to direct airflow about the divider 300 and into the recirculation flow path 334. Similar to the blades 266 of the blade pack 252, the divider 300 extends the full lateral length of the central chamber 234 and is thus mounted to the housing 218. Alternatively, one of ordinary skill will realize that the divider 300 may be spaced from the sides 288 of the housing 218 and thus may be mounted via lateral supports (not shown) or via another suitable attachment mechanism.

Similar to the inertial air separator 10, the inertial air separator 210 also includes an inner barrier 340 and an outer barrier 342, each extending axially outwardly from the inlet end 220, also herein referred to as an upstream end, of the housing 218. One of ordinary skill in the art will also appreciate that the divider 300 and barriers 340, 342 may extend around, such as fully around, the blade pack 252, if the blade pack 252 is suitably spaced from the housing 218. A restricted flow path portion 344 of the recirculation flow path 334 is defined by a winding path between the inner and outer barriers 340, 342 and the divider 300. The restricted portion 344 is located downstream of a particle trap area 346, for receiving dense or heavy particulate falling out of airflow moving through the recirculation flow path 334. As shown, the particle trap area 346 is isolated from the blade pack 252 and from the convoluted flow gaps 320 defined therein by the divider 300. The particle trap area 346 may be partially defined by a magnetic field inducing element, such as a magnet 350, for aiding in directing dense metallic particulate into the particle trap area 346.

Turning now to Fig. 12, yet another exemplary inertial air separator 410 is shown, which includes a blade pack 452. The inertial air separator 410 may be used in place of the inertial air separators 10, 140, and 210, and the discussion below omits many features of the inertial air separator 410 that are similar to those of the inertial air separators 10, 140, and 210. In addition, features of the inertial air separator 410 may be combined with those of the inertial air separators 10, 140, and 210. The blade pack 452 includes a plurality of curved laterally-extending blades 466 arranged in stacked orientation with respect to one another. A central axis 470 of the blade pack 452 is a curved axis thereby providing for different flow characteristics as compared to the inertial air separator 210 (Fig. 1 1 ) having a substantially straight central axis 262 of the blade pack 252.

Turning further to Fig. 13, another exemplary inertial air separator 610 having a blade pack 652 is shown. The inertial air separator 610 may be used in place of any other inertial air separator described herein and/or features of the inertial air separators may be combined. The blade pack 652 includes a plurality of curved blades having C-shape cross-sections. The blades 654 are configured with convex ends 656 oriented towards the outlet end 658 of the housing 660 and with concave ends 662 oriented towards the inlet end 664 of the housing 660. It will be appreciated that the blades 654 may instead have an opposite configuration.

Although the invention has been shown and described with respect to a certain embodiment or embodiments, it is obvious that equivalent alterations and modifications will occur to others skilled in the art upon the reading and understanding of this specification and the annexed drawings. In particular regard to the various functions performed by the above described elements (components, assemblies, devices, compositions, etc.), the terms (including a reference to a "means") used to describe such elements are intended to correspond, unless otherwise indicated, to any element which performs the specified function of the described element (i.e., that is functionally equivalent), even though not structurally equivalent to the disclosed structure which performs the function in the herein illustrated exemplary embodiment or embodiments of the invention. In addition, while a particular feature of the invention may have been described above with respect to only one or more of several illustrated embodiments, such feature may be combined with one or more other features of the other embodiments, as may be desired and advantageous for any given or particular application.