Drainage system for rotating crankcase ventilation systems

Abstract

A crankcase ventilation system includes a housing including inner wall. A coalescing filter element is disposed within the housing and is rotatable about an axis extending along an axial direction in the housing. The coalescing filter element includes an inner periphery defining a hollow interior and an outer periphery defining an exterior. The exterior faces the inner wall. A tangential drain is disposed at the inner wall and a lower drain is disposed at the inner wall axially below the tangential drain.

Description

DRAINAGE SYSTEM FOR ROTATING CRANKCASE VENTILATIONSYSTEMSCROSS-REFERENCE TO RELATED APPLICATION

[0001] This PCT Application claims the benefit and priority to U.S. Provisional Application No. 63 / 569,792, filed March 26, 2024, the contents of which are incorporated herein by reference in its entirety.TECHNICAL FIELD

[0002] The present disclosure relates generally to rotating crankcase ventilation systems.BACKGROUND

[0003] During operation of an internal combustion engine, a fraction of combustion gases can flow out of the combustion cylinder and into the crankcase of the engine. These gases are often referred to as “blowby” gases. The blowby gases include a mixture of aerosols, oils, and air. If vented directly to the ambient, the aerosols contained in the blowby gases can harm the environment. Accordingly, the blowby gases are often routed out of the crankcase via a crankcase ventilation system. The crankcase ventilation system may pass the blowby gases through a coalescer (i.e., a coalescing filter element) to remove a majority of the aerosols and oils contained in the blowby gases. The filtered blowby gases (“clean” gases) are then either vented to the ambient (in open crankcase ventilation systems) or routed back to the air intake for the internal combustion engine for further combustion (in closed crankcase ventilation systems).

[0004] Some crankcase ventilation systems utilize rotating crankcase ventilation filter elements, for example, rotating coalescer elements that increase the filter efficiency of crankcase ventilation systems by rotating the coalescer element during filtering. In rotating coalescer elements, the contaminants (e.g., oil droplets suspended and transported by blowby gases) are separated at least in part by centrifugal separation techniques.SUMMARY

[0005] One embodiment of the present disclosure relates to a crankcase ventilation system including a housing including an inner wall. A coalescing fdter element is disposed within the housing and is rotatable about an axis extending along an axial direction in the housing. The coalescing filter element includes an inner periphery defining a hollow interior and an outer periphery defining an exterior. The exterior faces the inner wall. A tangential drain is disposed at the inner wall and a lower drain is disposed at the inner wall axially below the tangential drain.

[0006] One embodiments of the present disclosure relates to a housing of a crankcase ventilation system including an inner wall defining a cavity configured to receive a coalescing filter element. The housing includes a tangential drain extending through the inner wall. The tangential drain is positioned at a first height along the inner wall. The housing includes a lower drain extending through the inner wall. The lower drain is positioned at a second height along the inner wall. The first height is axially above the second height.

[0007] These and other features, together with the organization and manner of operation thereof, will become apparent from the following detailed description when taken in conjunction with the accompanying drawings, wherein like elements have like numerals throughout the several drawings described below.BRIEF DESCRIPTION OF DRAWINGS

[0008] The foregoing and other features of the present disclosure will become more fully apparent from the following description and appended claims, taken in conjunction with the accompanying drawings. Understanding that these drawings depict only several implementations in accordance with the disclosure and are therefore, not to be considered limiting of its scope, the disclosure will be described with additional specificity and detail through use of the accompanying drawings.

[0009] FIG. l is a cross-sectional view of a crankcase ventilation system, according to an embodiment.

[0010] FIG. 2A is a cross-sectional view of a crankcase ventilation system, according to another embodiment.

[0011] FIG. 2B is a cross-sectional view of the crankcase ventilation system of FIG. 2A.

[0012] FIG. 3 is a top cross-sectional view of a housing of the crankcase ventilation system of FIG. 2A;

[0013] FIG. 4 is a top cross-sectional view of the crankcase ventilation system of FIG. 2A;

[0014] FIG. 5 is another cross-sectional view of the crankcase ventilation system of FIG.2A;

[0015] FIG. 6 is a cross-sectional view of the housing of the crankcase ventilation system of FIG. 2 A;

[0016] FIG. 7 is a perspective view of the crankcase ventilation system of FIG. 2A; and

[0017] FIG. 8 is another perspective view of the crankcase ventilation system of FIG. 2A, with the crankcase ventilation system oriented at an angle relative to a vertical plane.

[0018] Reference is made to the accompanying drawings throughout the following detailed description. In the drawings, similar symbols typically identify similar components, unless context dictates otherwise. The illustrative implementations described in the detailed description, drawings, and claims are not meant to be limiting. Other implementations may be utilized, and other changes may be made, without departing from the spirit or scope of the subject matter presented here. It will be readily understood that the aspects of the present disclosure, as generally described herein, and illustrated in the figures, can be arranged, substituted, combined, and designed in a wide variety of different configurations, all of which are explicitly contemplated and made part of this disclosure.DETAILED DESCRIPTION OF VARIOUS EMBODIMENTS

[0001] Embodiments described herein relate generally to rotating crankcase ventilation systems that include a drainage system for draining oil separated from blowby gas. In particular, embodiments described herein relate to crankcase ventilation systems that include a drainage system having a drain port tangential to the drainage flow.

[0019] Referring to FIG. 1, a cross-sectional view of a rotating crankcase ventilation system 100 is shown, according to an example embodiment. The crankcase ventilation system 100 receives fluids, namely blowby gases received from an internal combustion engine crankcase and removes aerosols, oils, and other particulates contained in the crankcase blowby gases. The crankcase ventilation system includes a housing 110 and a coalescing filter element 120. The coalescing filter element driven by various mechanisms (e.g., electrically driven, mechanically driven, pneumatically driven, etc.).

[0020] The coalescing filter element 120 rotates about an axis extending along an axial direction in the housing 110. As the coalescing filter element 120 rotates, the coalescing filter element separates oil, aerosols, and other contaminants contained the blowby gas. In some embodiments, the coalescing filter element 120 is driven to rotate by a mechanical coupling to a component of the engine. In some embodiments, the coalescing filter element 120 is driven to rotate by a fluid motor. In some embodiments, the coalescing filter element 120 is driven to rotate by an electric motor. In some embodiments, the coalescing filter element 120 is driven to rotate by magnetic coupling to a component of the engine.

[0021] The coalescing filter element 120 has an inner periphery defining a hollow interior, and an outer periphery defining an exterior. The housing 110 has an inner wall 112 facing the outer periphery of the coalescing filter element 120. An inlet supplies blowby gas from a crankcase into the housing 110 and to the hollow interior of the coalescing filter element 120. An outlet delivers cleaned separated air from the exterior of the coalescing filter element 120 out of the housing 110. A drain 114 provided below the coalescing filter element 120 delivers separated oil from the exterior of the coalescing filter element 120 out of the housing 110.

[0022] During operation of the crankcase ventilation system 100, blowby gas enters the housing 110 through the inlet and to the hollow interior of the coalescing filter element 120. From the hollow interior, the direction of blowby gas flow through the coalescing filter element 120 is inside-out, namely radially outwardly from the hollow interior to the exterior. Oil in the blowby gas is forced radially outwardly from the inner periphery by centrifugal force and drains from the outer periphery. The separated oil collects at a portion of the housing 110 proximate the lower outer edge of the coalescing filter element 120 and flows towards the drain 114 via gravity, as shown at arrow 102. In some embodiments, the drainage through the drain 114 may be provided through a one-way check valve. In some embodiments, the separated oil may be returned to the engine crankcase.[00023J At certain angular positions of the crankcase ventilation system 100, for example, upward tilts (e.g., 15 degrees, 20 degrees, 25 degrees, 30 degrees, 45 degrees, 60 degrees, 75 degrees), additional pressure in the housing 110 may be required to drain separated oil against gravity out of the housing 110. As a result, separated liquid carryover may occur. In some embodiments, high exit velocity of the separated oil may be needed to drain the separated oil.

[0024] Referring generally to FIGS. 2A-8, a crankcase ventilation system 200 is shown. Similar to the crankcase ventilation system 100 of FIG. 1, the crankcase ventilation system 200 is configured to receive fluids, namely blowby gases received from an internal combustion engine crankcase and remove aerosols, oils, and other particulates contained in the crankcase blowby gases. However, the drainage system in crankcase ventilation system 200 differs from the drainage system in crankcase ventilation system 100 by utilizing non-gravitational drainage. As such, the drainage system in crankcase ventilation system 200 may provide continuous drainage of the crankcase ventilation system 200 at varying angular positions.

[0025] The crankcase ventilation system 200 includes a housing 210 and a coalescing filter element 220 disposed within the housing 210. The coalescing filter element 220 rotates about an axis 250 extending along an axial direction in the housing 110. The coalescing filter element 220 has an outer periphery 222 (e.g., an outer or exterior surface) and a hollow interior 224. A lower edge of the coalescing filter element 220 comprises a plurality of drain channels 226. Atleast some of the oil removed from the blowby gases can exit the coalescing filter element 220 via a drain channel 226. In some embodiments, the coalescing filter element 220 is functionally and / or structurally similar to any of the coalescing filter elements described herein.

[0026] The housing 210 has an inner wall 212 facing the outer periphery 222 of the coalescing filter element 220. The inner wall 212 defines a cavity configured to receive the coalescing filter element 220. The housing 210 has an inlet 228. The inlet 228 supplies blowby gas from a crankcase into the housing 210 and to the hollow interior 224 of the coalescing filter element 220. In the embodiment shown in FIG. 2A, the inlet 228 can be oriented at an angle. For example, with the crankcase ventilation system 200 in a vertical position with the axis 250 extending vertically (e.g., perpendicular to a horizontal ground or floor), the inlet 228 is oriented at an angle relative to the horizontal ground or floor. For example, the inlet 228 is not parallel to a horizontal ground or floor or is not perpendicular to the axis 250. The housing 210 has an outlet 230. The outlet 230 delivers cleaned separated air from an exterior of the coalescing filter element 220 out of the housing 210. From the hollow interior 224, the direction of blowby gas flow through the coalescing filter element 220 is inside-out, namely radially outwardly from the hollow interior 224 to the outer periphery 222. Oil in the blowby gas is forced radially outwardly from the hollow interior 224 by centrifugal force and drains from the outer periphery 222.

[0027] The housing 210 has a bottom surface 232. The separated oil collects at or on the bottom surface 232 of the housing 210. The bottom surface 232, or a portion thereof, is proximate the lower edge of the coalescing filter element 220. The bottom surface 232 extends radially inward from the inner wall 212 of the housing 210.

[0028] The bottom surface 232 can have a plurality of portions that are disposed at different heights within the housing 210. For example, the bottom surface 232 can have a first portion 234. The first portion 234 extends radially inward from the inner wall 212. The first portion 234 has a first end 235 and a second end 236. In some embodiments, the first end 235 and the second end 236 can be disposed at the same axial height. For example, the first portion 234 can have a flat, planar surface that extends along a horizontal plane that is perpendicular to an axialdirection of the housing 210. In some embodiments, the first end 235 and the second end 236 can be disposed at different axial heights. For example, the first end 235 can be positioned at a location axially higher than the second end 236 such that the first portion 234 has a helical downward slope.

[0029] The bottom surface 232 can have a second portion 237. The second portion 237 can be disposed at an axially lower position than the first portion 234. In some embodiments, the second portion 237 can extend between the first end 235 and the second end 236 of the first portion 234.

[0030] In some embodiments, the bottom surface 232 can have a third portion 238. The second portion 237 can be disposed at an axially lower position than the first portion 234 and the third portion 238 can be disposed at an axially lower position than the second portion 237. The second portion 237 and the third portion 238 can be disposed between the first end 235 and the second end 236 of the first portion 234.

[0031] In some embodiments, the housing 210 includes a projection 240. The projection 240 extends radially inward from the inner wall 212. The projection 240 is positioned at an axially higher position than the bottom surface 232. The projection 240 is configured to guide separated oil into the tangential drain 216. For example, a surface of the projection 240 can be parallel with the tangential drain 216 such that the oil can slide along the projection 240 and straight into the tangential drain 216.

[0032] The crankcase ventilation system 200 includes a drainage system 213. The separated oil exits the housing 210 via the drainage system 213. The drainage system 213 includes a lower drain 214 and a tangential drain 216. The drainage system 213 in the crankcase ventilation system 200 allows separated oil to flow in two separate flow paths. In a first flow path 217, the separated oil exits the housing 210 through the tangential drain 216. In a second flow path 218, the separated oil exits the housing 210 through the lower drain 214.

[0033] In some embodiments, the lower drain 214 and the tangential drain 216 are aligned along an axial plane. In some embodiments, the lower drain 214 and the tangential drain 216are axially offset. In some embodiments, the lower drain 214 and the tangential drain 216 are substantially parallel to each other. In some embodiments, the lower drain 214 and the tangential drain 216 are angularly offset (e.g., vertically, horizontally, or both) from each other. In some embodiments, conduits may be fluidly coupled with the lower drain 214 and the tangential drain 216.

[0034] The tangential drain 216 is located at the inner wall 212 at an axially intermediate location above the lower drain 214. For example, the tangential drain 216 is positioned at a first height along the inner wall 212. The lower drain 214 is disposed at a second height along the inner wall 212. The first height is axially above the second height. In some embodiments, the tangential drain 216 is located at the inner wall 212 proximate the lower outer edge of the coalescing filter element 220.

[0035] The tangential drain 216 defines an orifice that extends through the inner wall 212 of the housing 210. The tangential drain 216 defines a central axis 219. The tangential drain 216 is oriented at a drain angle 255 relative to the inner wall 212. For example, as shown in FIG. 3, the tangential drain 216 extends through the inner wall 212 at a point 260. The point 260 is defined where the central axis 219 intersects the inner wall 212. At the point 260, the inner wall 212 extends in a first direction 265. The first direction 265 being tangential to the inner wall 212 at that point (e.g., a line in the first direction 265 only intersects the curved inner wall 212 at the point 260). The tangential drain 216 extends from the point 260 in a second direction 275. The angle between the first direction 265 and the second direction 270 is the drain angle 255. The tangential drain 216 is oriented to create a small drain angle 255. For example, the drain angle 255 is less than 45 degrees. As shown in FIG. 3, the drain angle 255 can be less than 30 degrees. It is easier for the separated oil to flow from the inner wall 212 into the tangential drain 216 with a smaller drain angle 255.

[0036] The tangential drain 216 is axially aligned with the tangential velocity of a portion of the oil in the coalescing filter element 220. For example, the drain channels 226 of the coalescing filter element 220 can be axially aligned with the central axis 219. Alignment of the drain channels 226 with the central axis 219 of the tangential drain 216 allows oil exiting thecoalescing filter element 220 via the drain channels 226 to flow out of the housing 210 via the tangential drain 216. The placement of the tangential drain 216 utilizes high swirl velocity at the inner wall 212 of the housing to aid in drainage of the separated oil. Therefore, the tangential drain 216 allows the crankcase ventilation system 200 to drain separated oil when the crankcase ventilation system 200 is oriented in various positions in which gravitational drainage may be inadequate. The placement of the tangential drain 216 further allows for more compact crankcase ventilation system designs.

[0037] The tangential drain 216 is disposed axially above the bottom surface 232. The lower drain 214 is disposed at an axially lower location than at least a portion of the bottom surface 232. For example, in the embodiment shown in FIG. 3, the bottom surface 232 includes a first portion 234 and second portion 237. The second portion is disposed at an axially lower location than the first portion. The tangential drain can be positioned at an axially higher location than the first portion and the lower drain can be positioned axially between the first portion and the second portion.

[0038] As shown in FIG. 3, the bottom surface 232 includes a third portion 238. The second portion 237 is at an axially lower location than the first portion 234, and the third portion 238 is at an axially lower location than the second portion 237. The lower drain 214 extends through the inner wall 212 at an axial position between the second portion 237 and the third portion 238.

[0039] As shown in FIG. 3, the tangential drain 216 is positioned adjacent a projection 240. For example, the projection 240 and the tangential drain 216 are positioned at the same axial height. The projection 240 can facilitate movement of the separated oil into the tangential drain 216. The projection 240 is configured to change the orientation of the inner wall 212 at the point 260 where the tangential drain 216 extends through the inner wall 212 to reduce the drain angle 255.

[0040] As shown in FIG. 8, the crankcase ventilation system 200 includes at least one check valve 221. For example, a check valve 221 can be disposed in or coupled to the tangential drain 216. A check valve 221 can be disposed in or coupled to the lower drain 214.In some embodiments, drainage through the tangential drain 216 and / or the lower drain 214 may be provided through a check valve 221.

[0041] As shown in FIGS. 2A-4, the tangential drain 216 is an orifice extending through the inner wall 212 of the housing 210. In some embodiments, the tangential drain 216 comprises a plurality of drain holes.

[0042] The lower drain 214 is located at the inner wall at a lower axial location than the tangential drain 216. Separated oil flows towards the lower drain 214 via gravity. In some embodiments, the lower drain 214 and the tangential drain 216 are aligned along the same axial (e.g., vertical) plane. In some embodiments, the lower drain 214 and the tangential drain 216 can be vertically offset (e.g., extend in different axial planes). In some embodiments, the lower drain 214 and the tangential drain 216 are substantially parallel to each other. In some embodiments, the lower drain 214 and the tangential drain 216 are angularly offset (e.g., vertically, horizontally, or both) from each other. In some embodiments, the lower drain 214 and the tangential drain 216 allow separated oil to flow perpendicular to the axis extending along an axial direction in the housing 210.

[0043] In some embodiments, the lower drain 214 is an orifice in the side wall of the housing 210. In some embodiments, the lower drain 214 comprises a plurality of drain holes. In some embodiments, drainage through the lower drain 214 may be provided through a check valve. In some embodiments, the lower drain 214 may be omitted.

[0044] Therefore, the drainage system of crankcase ventilation system 200 provides both gravitational drainage and drainage aided by the high swirl velocity. In some embodiments, separated oil drains through the tangential drain 216 when the crankcase ventilation system 200 is tilted upward. In some embodiments, a smaller portion of the separated oil drains through the lower drain 214.

[0045] Referring to FIG. 8, the crankcase ventilation system 200 is shown oriented at an angle. In some embodiments, the crankcase ventilation system 200 can be oriented at an angle such that the axis 250 of the crankcase ventilation system 200 is angled relative to a verticalplane (e.g., is not perpendicular to a horizontal plane). A high swirl velocity of the crankcase ventilation system 200 allows oil to continue to drain from the crankcase ventilation system 200 via the tangential drain 216 when the crankcase ventilation system 200 is oriented at an angle.

[0046] It should be noted that the term “example” as used herein to describe various embodiments is intended to indicate that such embodiments are possible examples, representations, and / or illustrations of possible embodiments (and such term is not intended to connote that such embodiments are necessarily extraordinary or superlative examples).

[0047] As utilized herein, the term “substantially” and similar terms are intended to have a broad meaning in harmony with the common and accepted usage by those of ordinary skill in the art to which the subject matter of this disclosure pertains. It should be understood by those of skill in the art who review this disclosure that these terms are intended to allow a description of certain features described and claimed without restricting the scope of these features to the precise numerical ranges provided. Accordingly, these terms should be interpreted as indicating that insubstantial or inconsequential modifications or alterations of the subject matter described and claimed (e.g., within plus or minus five percent of a given angle or other value) are considered to be within the scope of the invention as recited in the appended claims.

[0048] The terms “coupled,” “connected,” and the like as used herein mean the joining of two members directly or indirectly to one another. Such joining may be stationary (e.g., permanent) or moveable (e.g., removable or releasable). Such joining may be achieved with the two members or the two members and any additional intermediate members being integrally formed as a single unitary body with one another or with the two members or the two members and any additional intermediate members being attached to one another.

[0049] References herein to the positions of elements (e.g., “top,” “bottom,” etc.) are merely used to describe the orientation of various elements in the FIGURES. It should be noted that the orientation of various elements may differ according to other exemplary embodiments, and that such variations are intended to be encompassed by the present disclosure.

[0050] It is important to note that the construction and arrangement of the various exemplary embodiments are illustrative only. Although only a few embodiments have been described in detail in this disclosure, those skilled in the art who review this disclosure will readily appreciate that many modifications are possible (e.g., variations in sizes, dimensions, structures, shapes and proportions of the various elements, values of parameters, mounting arrangements, use of materials, colors, orientations, etc.) without materially departing from the novel teachings and advantages of the subject matter described herein. Other substitutions, modifications, changes and omissions may also be made in the design, operating conditions and arrangement of the various exemplary embodiments without departing from the scope of the embodiments described herein.[00051J While this specification contains many specific implementation details, these should not be construed as limitations on the scope of any embodiment or of what may be claimed, but rather as descriptions of features specific to particular implementations of particular embodiments. Certain features described in this specification in the context of separate implementations can also be implemented in combination in a single implementation. Conversely, various features described in the context of a single implementation can also be implemented in multiple implementations separately or in any suitable subcombination. Moreover, although features may be described above as acting in certain combinations and even initially claimed as such, one or more features from a claimed combination can in some cases be excised from the combination, and the claimed combination may be directed to a subcombination or variation of a subcombination.

Claims

WHAT IS CLAIMED IS:

1. A crankcase ventilation system comprising: a housing comprising an inner wall; a coalescing filter element disposed within the housing, the coalescing filter element rotatable about an axis extending along an axial direction in the housing, the coalescing filter element comprising an inner periphery defining a hollow interior and an outer periphery defining an exterior, the exterior facing the inner wall; a tangential drain disposed at the inner wall of the housing; and a lower drain disposed at the inner wall axially below the tangential drain.

2. The crankcase ventilation system of claim 1, wherein the tangential drain is disposed proximate a lower edge of the coalescing filter element.

3. The crankcase ventilation system of claim 2, wherein the coalescing filter element comprises a plurality of drain channels disposed at the lower edge of the coalescing filter element, the plurality of drain channels axially aligned with the tangential drain.

4. The crankcase ventilation system of claim 1, wherein: the tangential drain defines a central axis, the central axis intersects the inner wall at a point; the inner wall extends in a first direction from the point and the tangential drain extends in a second direction from the point; the first direction and the second direction define a drain angle, the drain angle being less than 45 degrees.

5. The crankcase ventilation system of claim 1, wherein the tangential drain is an orifice extending through the inner wall of the housing.

6. The crankcase ventilation system of claim 1, wherein the lower drain and the tangential drain are aligned along a single axial plane.

7. The crankcase ventilation system of claim 1, wherein the housing comprises a bottom surface, wherein the tangential drain is disposed axially above the bottom surface.

8. The crankcase ventilation system of claim 7, wherein the bottom surface comprises a first portion and a second portion, wherein a first end and a second end of the first portion are disposed at a same height and the second portion is disposed at an axially lower location than the first portion, the second portion extending between the first end and the second end of the first portion.

9. The crankcase ventilation system of claim 7, wherein the bottom surface comprises a first portion and a second portion, wherein a first end of the first portion is at an axially higher location than a second end of the first portion such that the first portion has a helical downward slope, and the second portion is disposed at an axially lower location than the first portion.

10. The crankcase ventilation system of claim 7, wherein the bottom surface comprises a first portion, a second portion, and a third portion, the second portion at an axially lower location than the first portion, and the third portion at an axially lower location than the second portion, the lower drain extending through the inner wall at an axial position between the second portion and the third portion.

11. The crankcase ventilation system of claim 1, wherein the housing comprises a projection extending radially inward from the inner wall, the projection adjacent the tangential drain.

12. The crankcase ventilation system of claim 1, further comprising: a first check valve disposed in the tangential drain; and a second check valve disposed in the lower drain.

13. A housing for a crankcase ventilation system, the housing comprising: an inner wall defining a cavity configured to receive a coalescing filter element; a tangential drain extending through the inner wall, the tangential drain positioned at a first height along the inner wall; and a lower drain extending through the inner wall, the lower drain positioned at a second height along the inner wall, the first height axially above the second height.

14. The housing of claim 13, wherein: the tangential drain defines a central axis, the central axis intersects the inner wall at a point; the inner wall extends in a first direction from the point and the tangential drain extends in a second direction from the point; the first direction and the second direction define a drain angle, the drain angle being less than 45 degrees.

15. The housing of claim 13, wherein the lower drain and the tangential drain are aligned along a single vertical plane.

16. The housing of claim 13, further comprising a bottom surface, wherein the tangential drain is disposed axially above the bottom surface and the lower drain is disposed axially below at least a portion of the bottom surface.

17. The housing of claim 16, wherein the bottom surface comprises a first portion and second portion, wherein a first end and a second end of the first portion are disposed at a first axial location and the second portion is disposed at a second axial location that is lower than the first axial location, the second portion extending between the first end and the second end of the first portion.

18. The housing of claim 16, wherein the bottom surface comprises a first portion and a second portion, the second portion axially below the first portion, wherein the tangential drain is positioned at an axial location higher than the first portion and the lower drain is positioned axially between the first portion and the second portion.

19. The housing of claim 13, further comprising a projection extending radially inward from the inner wall, the projection adjacent the tangential drain.

20. The housing of claim 13, wherein the tangential drain is an orifice extending through the inner wall.

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