FIELD
The present disclosure relates to two-stage gas-liquid separators and methods for separating liquids from a gas-liquid stream.
BACKGROUND
U.S. Pat. No. 7,870,850, which is hereby incorporated by reference in its entirety, discloses a crankcase ventilation system for an internal combustion engine that has a jet pump suctioning scavenged separated oil from the oil outlet of an air/oil separator and pumping same to the crankcase.
U.S. Pat. No. 7,614,390, which is hereby incorporated by reference in its entirety, discloses a two stage drainage gas-liquid separator assembly including an inertial gas-liquid impactor separator haying one or more nozzles accelerating a gas-liquid stream therethrough, and an inertial impactor in the path of the accelerated gas-liquid stream and causing liquid particle separation from the gas-liquid stream. The separator assembly further includes a coalescer filter downstream of the inertial gas-liquid impactor separator and effecting further liquid particle separation, and coalescing separated liquid particles.
U.S. Pat. No. 6,290,738, which is hereby incorporated by reference in its entirety, discloses an inertial gas-liquid separator. A housing has an inlet for receiving a gas-liquid stream and an outlet for discharging a gas stream. A nozzle structure in the housing has a plurality of nozzles receiving the gas-liquid stream from the inlet, and accelerating the gas-liquid stream through the nozzles. An inertial collector in the housing in the path of the accelerated gas-liquid stream causes a sharp directional change thereof and in preferred form has a rough porous collection surface causing liquid particle separation from the gas-liquid stream of smaller size liquid particles than a smooth non-porous impactor impingement surface and without the sharp cut-off size of the latter, to improve over all separation efficiency including for smaller liquid particles. Various housing configurations and geometries are provided.
SUMMARY
This Summary is provided to introduce a selection of concepts that are further described below in the Detailed Description. This Summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used as an aid in limiting the scope of the claimed subject matter.
The present disclosure is directed to a two-stage gas-liquid separator assembly comprising a housing having a flowpath therethrough from upstream to downstream, the housing having an inlet for receiving a gas-liquid stream and an outlet for discharging a gas stream. A first plenum chamber is defined by the housing and comprises a pre-separator that causes liquid to separate from the gas-liquid stream and to drain to a lower portion of the first plenum chamber. A second plenum chamber is defined by the housing and comprises a main separator downstream of the pre-separator that further causes liquid to separate from the gas-liquid stream and to drain to a lower portion of the second plenum chamber. A first drain port in the housing drains liquid from the lower portion of the first plenum chamber and a second drain port in the housing drains liquid from the lower portion of the second plenum chamber. Liquid drains from the lower portions of the first and second plenum chambers through the first and second drain ports, respectively, regardless of a pressure difference between a pressure in the first plenum chamber and a pressure in the second plenum chamber.
Also disclosed is a method for separating liquid from a gas-liquid stream. The method comprises: introducing the gas-liquid stream into a housing having a flowpath therethrough from upstream to downstream. The method further comprises separating liquid from the gas-liquid stream in a first plenum chamber defined by the housing and draining liquid to a lower portion of the first plenum chamber and through a first drain port. The method further comprises further separating liquid from the gas-liquid stream in a second plenum chamber defined by the housing and downstream of the first plenum chamber and draining liquid to a lower portion of the second plenum chamber and through a second drain port. The method further comprises pumping liquid from the lower portions of the first and second plenum chambers through the first and second drain ports, respectively.
An assembly for removing scavenged liquid from a two-stage gas-liquid separator is also disclosed. The assembly comprises a first suction port receiving scavenged liquid from a first stage of the gas-liquid separator and a second suction port receiving scavenged liquid from a second stage of the gas-liquid separator. A first jet orifice accelerates a pressurized fluid into the first suction port. A second jet orifice accelerates the pressurized fluid into the second suction port. A feed bore supplies both the first and second jet orifices with the pressurized fluid. A common mixing bore receives the pressurized fluid from the first and second jet orifices and receives scavenged liquid from the first and second stages of the gas-liquid separator.
BRIEF DESCRIPTION OF THE DRAWINGS
Examples of assemblies and methods for use with a crankcase ventilation unit are described with reference to the following Figures. The same numbers are used throughout the Figures to reference like features and like components.
FIG. 1 is a schematic representation of one embodiment of a crankcase ventilation system;
FIG. 2 illustrates one embodiment of a two-stage gas-liquid separator, in one embodiment, for use in a crankcase ventilation system;
FIG. 3 illustrates a flowpath through the gas-liquid separator of FIG. 2 when viewed from an opposite side than in FIG. 2;
FIGS. 4 and S show sectional views through the gas-liquid separator of FIGS. 2 and 3, wherein FIG. 4 is a top view and FIG. 5 is a bottom view;
FIG. 6 illustrates a detail view of a lower portion of the gas-liquid separator;
FIG. 7 illustrates a sectional detail view of the lower portion of the gas-liquid separator and one embodiment of a jet pump for use with the gas-liquid separator;
FIG. 8 illustrates a top sectional view of the jet pump;
FIG. 9 is a schematic representation of flow through a jet pump;
FIG. 10 illustrates another embodiment of a two-stage gas-liquid separator; and
FIG. 11 is a schematic representation of another embodiment of a crankcase ventilation system.
FIG. 12 depicts one embodiment of a method for separating liquid from a gas-liquid stream according to the present disclosure.
DETAILED DESCRIPTION
Crankcase ventilation systems are used in conjunction with internal combustion engines that generate blowby gas in a crankcase containing engine oil and oil aerosol. A gas-liquid separator, or an aerosol-oil or air-oil separator, has an inlet receiving blowby gas and oil aerosol from the crankcase. An air outlet discharges clean blowby gas to the atmosphere or back to the engine air intake. An oil outlet discharges scavenged separated oil back to the crankcase. The gas-liquid separator has a pressure drop thereacross such that the pressure at its inlet and in the crankcase is higher than the pressure at its air outlet and oil outlet. The pressure differential between the crankcase and the oil outlet of the separator can cause back flow of oil from the higher pressure crankcase to the lower pressure oil outlet. Further, depending on the location of venting of the crankcase ventilation system, a high volume of liquid entering the gas-liquid separator may be present.
According to the present disclosure, FIG. 1 illustrates a crankcase ventilation system .10 for an internal combustion engine 12 generating blowby gas in a crankcase 14 containing engine oil 16 and oil aerosol. The system 10 includes a gas-liquid separator 18, such as an air-oil separator, having an inlet 20 receiving blowby gas and oil aerosol from the crankcase 14 (shown by arrow 21) and having an air outlet 22 discharging clean blowby gas to the atmosphere (shown by arrow 23) or returning clean blowby gas to the engine air intake (see FIG. 11). The gas-liquid separator 18 further includes an oil outlet 24 discharging scavenged separated oil back to the crankcase 14, as will be further described herein below.
The system 10 further includes a jet pump 26 pumping scavenged separated oil from oil outlet 24 back to crankcase 14. The engine 12 includes an oil circulation system 28 circulating engine oil 16 from crankcase 14 through an oil pump 30. The oil pump 30 delivers pressurized oil through filter 32 to selected engine components such as a piston 34 and a crankshaft 36, and then back to crankcase 14. Pressurized oil is also delivered through filter 32 to jet pump 26.
Now with reference to FIG. 2, one embodiment of a gas-liquid separator 18 will be described, The gas-liquid separator 18 comprises a housing 38 haying a flowpath therethrough from upstream (at inlet 20) to downstream (at outlet 22). The housing has an inlet 20 for receiving a gas-liquid stream and an outlet 22 for discharging a gas stream. The housing 38 comprises a first plenum chamber 40 defined by the housing 38 and comprising a pre-separator 41 that causes liquid to separate from the gas-liquid stream and to drain to a lower portion 42 of the first plenum chamber 40. The gas-liquid separator 18 further comprises a second plenum chamber 44 defined by the housing 38 and comprising a main separator 43 downstream of the pre-separator 41 that further causes liquid to separate from the vas-liquid stream and to drain to a lower portion 46 of the second plenum chamber 44.
FIG. 3 shows flow through the gas-liquid separator 18. The gas-liquid stream enters the housing 38 at the inlet .20 as shown at arrow 48. The gas-liquid stream is then routed through the pre-separator 41, for example a cyclone separator as shown herein and further described herein below, that causes liquid to separate from the gas-liquid stream as it is guided through the housing 38 as shown at arrows 50. Some liquid is separated from the gas-liquid stream in the pre-separator, and the pre-separated gas-liquid stream then enters the second plenum chamber 44 as shown at the arrow 52. The second plenum chamber 44 comprises a main separator 43, for example an impactor separator as shown herein, and further described herein below. The gas-liquid stream is accelerated through the impactor separator as shown at arrows 54 and then exits the impactor separator as shown at arrows 56. The gas stream then exits the housing 38 via the outlet 22 as shown at arrow 58. According to the present disclosure, separated liquid drains from the housing 38 as shown at arrows 60 and 62, and further described herein below. A first drain port 64 in the housing 38 drains liquid from the lower portion 42 of the first plenum chamber 40. A second drain port 66 in the housing 38 drains liquid from the lower portion 46 of the second plenum chamber 44. Liquid drains from the lower portions 42, 46 of the first and second plenum chambers 40, 44, respectively, through the first and second drain ports 64, 66 regardless of a pressure difference between a pressure in the first plenum chamber 40 and a pressure in the second plenum chamber 44, as further described herein below.
With respect to each of FIGS. 2-6, in the embodiment shown therein, the pre-separator 41 is a cyclone separator, but the pre-separator 41 could comprise various other types of gas-liquid separators. Air enters the inlet 20 tangentially as shown at arrow 48, is directed around a baffle 94, and is guided around a curve defined by the inner surface 110 of the housing 38 as shown by arrows 50. The baffle 94 minimizes pressure drop as air enters the housing 38. Air is somewhat guided by a chimney 96 supported by the housing 38 and extending from the first plenum chamber 40 into the second plenum chamber 44 that allows for the gas-liquid stream to flow therethrough. As the gas-liquid stream is circulated as shown by the arrows 50, heavier liquid particles drop to the lower portion 42 of the first plenum chamber 40. Additionally, heavier liquid particles collect along the inner surface 110 of the housing 38 and drain to the lower portion 42 of the first plenum chamber 40. Liquid that collects in the lower portion 42 of the first plenum chamber 40 thereafter drains from the housing 38 via the first drain port 64. Upon completing the cyclonic flow and separating heavier oil particles, flow exits directly through the chimney 96 into the impactor separator or coalescer separator. The chimney 96 includes the second drain port 66, in the example shown comprising a tube 114 that extends down to the jet pump 26. The downstream end 100 of the chimney 96 is directly molded to the main separator 43 (FIG. 2).
In the embodiment shown in FIGS. 2-5, the main separator 43 comprises an impactor separator comprising a nozzle plate 98 coupled to a downstream end 100 of the chimney 96 and having a plurality of nozzles 102 therethrough that accelerate the gas-liquid stream toward an impaction plate 104 downstream of the nozzle plate 98. This acceleration is shown by the arrows 54 in FIG. 3. in the embodiment shown, the main separator 43 is a variable impactor separator that further comprises a valve comprising a spring 150 and disc 152 assembled into a cup 153 with the nozzle plate 98 sonic welded, or in an alternative embodiment spin welded, threaded in, glued, or the like, to the downstream end 100 of the chimney 96. In the configuration shown in FIG. 2, the spring 150 and disc 152 are in a closed-disc valve configuration. However, when the pressure produced by flow through the chimney 96 is great enough to overcome the force of the spring 150, the disc 152 is unseated from the cup 153 and the gas-liquid stream flows into the cup 153 and then through the nozzle plate 98. Different numbers and sizes of nozzles 102 and different springs 150 may be used depending on the engine 12. The variable impactor separator and related components can be modified to accommodate a variety of flow ranges, restriction, and efficiency requirements.
In the embodiment shown, a shroud 106 extends circumferentially and downwardly from the impaction plate 104 and surrounds at least the downstream end 100 of the chimney 96, The shroud 106 causes the gas stream to flow as shown by arrows 56. Liquid particles that are separated by a sharp directional change in flow caused by the gas-liquid stream hitting the impaction plate 104 drip from the shroud 106 and fall to the lower portion 46 of the second plenum chamber 44. Separation with an impactor separator is described in U.S. Pat. No. 6,290,738, which was incorporated by reference in its entirety herein above, and will thus not be explained in more detail herein.
As shown in FIGS. 2, 3, and 6, the lower portion 46 of the second plenum chamber 44 comprises a funnel 108 that slopes downwardly from an inner surface 110 of the housing 38 to an external wall 112 of the chimney 96 so as to drain liquid to the second drain port 66. In the embodiment shown, the second drain port 66 comprises a tube 114 extending from the lower portion 46 of the second plenum chamber 44, specifically from the lowest portion of the funnel 108, through the first plenum chamber 40 to the jet pump 26. The tube 114 is hermetically sealed from the first plenum chamber 40, such that the pressure in the first plenum chamber 40 does not affect drainage of oil through the tube 114. In the embodiment shown herein, the tube 114 is coupled to the jet pump 26 via a cylindrical projection 115 extending from the lower portion 42 of the first plenum chamber 40.
The gas-liquid separator 18 further comprises a conduit 68, FIG. 3, coupled to the housing 38 and in fluid communication with both the first and second drain ports 64, 66 that conveys liquid from the lower portions 42, 46 of the first and second plenum chambers 40, 44 away from the housing 38, as shown by arrows 60 and 62. In the embodiment shown herein, the conduit 68 comprises a pump that removes liquid from the lower portions 42, 46 of the first and second plenum chambers 40, 44 through the first and second drain ports 64, 66, respectively. In one embodiment, the pump comprises a jet pump 26 (see FIGS. 7-9) in fluid communication with both the first and second drain ports. 66 In the embodiment shown herein, the jet pump 26 is bolted to a lower portion 140 of the housing 38 of the gas-liquid separator 18. Alternatively, the jet pump 26 could be integrally molded to the lower portion 140, FIGS. 2 and 3, of the housing 38 of the gas-liquid separator 18 or coupled to the housing in some other manner.
Now with reference to FIGS. 7-9, the jet pump 26 will be described in more detail. As shown schematically in FIG. 9, a jet pump 26 is operated by a motive fluid directed through a reduced diameter jet orifice 72 into a larger diameter mixing bore 74 having a suction chamber 76 there around. The momentum exchange between the high velocity motive jet flow from motive jet orifice 72 and the lower velocity surrounding fluid in mixing bore 74 creates a pumping effect which pumps fluid from suction chamber 76, for example as shown in the flow diagram. Examples of jet pumps are described in “The Design of Jet Pumps”, Gustav Flugel, National Advisory Committee for Aeronautics, Technical Memorandum No. 982, 1939; “Jet-Pump Theory and Performance with Fluids of High Viscosity”, R. G. Cunningham, Transactions of the ASME, November 1957, pages 1807-1820. In the embodiment of FIG. 9, jet pump 26 is a fluid-driven jet pump having. a pressurized jet orifice at 72 receiving pressurized motive fluid from a source of pressurized fluid, such as oil pump 30, a suction chamber at 76 receiving separated oil from oil outlet 24 of gas-liquid separator 18, and an output at mixing bore 74 delivering jet-pumped oil to crankcase 14, as shown in FIG. 1.
Referring now to FIGS. 7 and 8, in the embodiment shown therein, the jet pump 26 comprises a first jet orifice 78 accelerating pressurized fluid so as to pump liquid from the first drain port 64 and a second jet orifice 80 accelerating pressurized fluid so as to pump liquid from the second drain port 66. First and second jet orifices 78, 80 correspond to jet orifice 72 shown in the schematic of FIG. 9. The jet pump 26 also comprises a feed bore 82 that supplies the pressurized fluid to both the first and second jet orifices 78, 80. The feed bore 82 is supplied with pressurized fluid via motive line 125 as shown in FIGS. 1 and 8, or motive line 13$ as shown in FIG. 11. The jet pump 26 further comprises a first suction port 84 that receives liquid from the first drain port 64 and pressurized fluid from the first jet orifice 78, and a second suction port 86 that receives liquid from the second drain port 66 and pressurized fluid from the second jet orifice 80. Suction ports 84, 86 correspond to suction chamber 76 in the schematic of FIG. 9. The jet pump 26 comprises a common mixing bore 88 that receives liquid from both the first suction port 84 and the second suction port 86. Between the common mixing bore 8$ and the first and second. suction ports 84, 86, are intermediate mixing bores 90, 92, respectively. Mixing bores 88, 90. and 92 correspond to mixing bore 74 in the schematic of FIG. 9.
With continued reference to FIGS. 7 and 8, an assembly for removing scavenged liquid from a two-stage gas-liquid separator will be described. The assembly comprises a first suction port 84 receiving scavenged liquid from a first stage, such as pre-separator 41, of the gas-liquid separator 18. The assembly comprises a second suction port 86 receiving scavenged liquid from a second stage, such as a main separator 43, of the gas-liquid separator 18. A first jet orifice 78 accelerates a pressurized fluid into the first suction port 84. A second jet orifice 80 accelerates the pressurized fluid into the second suction port 86. A feed bore 82 supplies both the first and second jet orifices 78, 80 with the pressurized fluid. A common mixing bore 88 receives the pressurized fluid from the first and second jet orifices 78, 80 and receives scavenged liquid from the first and second stages of the gas-liquid separator. The assembly further comprises a first connection port 120 conveying liquid from an outlet, such as first drain port 64 in the first stage of the gas-liquid separator 18 to the first suction port 84, and a second connection port 122 conveying liquid from an outlet, such as second drain port 66 in the second stage of the gas-liquid separator 18 to the second suction port 86. In the embodiment shown, the first and second suction ports 84, 86 extend perpendicularly to a flow of the accelerated pressurized fluid flowing from the first and second jet orifices 78, 80, respectively. (See also FIG. 9) As shown in FIGS. 1 and 8, the assembly can further comprise a drain line 124 coupled to the mixing bore 88 that drains the scavenged liquid from the mixing bore 88 to the crankcase 14 of the engine 12.
Now with reference to FIG. 10, a second embodiment of a gas-liquid separator 18′ will be described. The gas-liquid separator 18′ comprises an inlet 20 for receiving a gas-liquid stream and an outlet 22 for discharging a gas stream. As in the first embodiment, the second embodiment of the gas-liquid separator 18′ comprises a pre-separator 41 that is a cyclone separator having an arched baffle 94 that guides the gas-liquid stream around the inner surface 110 of the housing 38 within the first plenum chamber 40. The gas-liquid stream is then directed upward through the chimney 96. Here, the gas-liquid stream is directed through a main separator 43, which in this embodiment is a coalescer separator comprising a filter media 116 coupled to the downstream end 100 of the chimney 96. Air flows in an inward-out (inside-out) direction through the filter media 116, as shown by the arrows 118. The filter media 116 has properties that cause oil to coalesce within/on the filter media 116 and thereby to separate from the gas-liquid stream.
While in the embodiment shown in FIG. 1 the pressurized fluid is oil, in the embodiment shown in FIG. 11, the pressurized fluid is air. As shown in FIG. 11, the air is provided to the jet pump 26 via motive line 138. A turbocharger 126, in the example shown, fed with gas exiting, the outlet 22 of the gas-liquid separator 18, provides the pressurized air to the jet pump 26 as shown by arrows 128. Alternatively, an air compressor, for example as shown in dashed lines at 130, or a tank of compressed air, for example as shown in dashed lines at 132, can provide the pressurized air to the jet pump 26. One or more optional check valves 134, 136 can be provided in the motive line 138 and/or the drain line 124 to prevent backflow in a condition of low or negative air supply pressure.
One result of the assembly described herein is an integrated product that separates coarse liquid oil challenge before the main separator 43, for example with a pre-separator 41, such as a cyclone separator, which coarse liquid oil challenge is drained back to the engine 12 via a first drain port 64, in order to achieve high efficiency. The air-oil mixture is then separated in a main separator 43, such as an impactor separator (FIG. 1) or a coalescer separator FIG. 10) and is drained via a second drain port 66 from the housing 38.
The jet pump 26 provides a way to drain the housing 38 from scavenged oil regardless of the pressure difference between a pressure in the first plenum chamber 40 and a pressure in the second plenum chamber 44. The two chambers 40, 44 are hermetically sealed from one another everywhere except for at nozzles 102. Hermetic seals are provided at first and second drain ports 64, 66 so as to prevent flow from leaking from the first plenum chamber 40, which is at a higher pressure, to the second plenum chamber 44, which is at a lower pressure, for example via the second drain port 66. If flow leaked in this manner, it would not be possible to drain the second plenum chamber 44 due to increased pressure in the second drain port 66. A high pressure due to oil build up from the second plenum chamber 44 is not required to overcome a pressure within the first plenum chamber 40 in order for the housing 38 to be drained of scavenged oil because the jet pump 26 actively drains both plenum chambers 40, 44 instead of relying on an oil column head to overcome the pressure difference. This eliminates the need for a check valve between the chambers 40, 44. This further eliminates the need to design the gas-liquid separator 18 so as to limit pressure difference to enable a check valve to operate at certain engine conditions. This also allows the gas-liquid separator 18 to function in a wide range of engine conditions without concern for restriction affecting oil return capability.
The jet orifices 78, 80 within the jet pump 26 can be fed off of a single feed, such as through feed bore 82, and evacuated into a single drain line 124, such as through common mixing bore 88. The high pressure fluid jetting through the first and second jet orifices 78, 80 allows oil to be drained from the housing 38 independent of the pressure within the housing 38. Such drainage is independent of both the relative pressures between the pressure within the first and second plenum chambers 40,44 and independent, of the pressure within the crankcase 14.
Now referring to FIG. 12, in another example, a method for separating a liquid from a gas-liquid stream is provided. The method comprises introducing the gas-liquid stream into a housing 38 having a flowpath therethrough from upstream to downstream, as shown at box 201. The method further comprises separating liquid from the gas-liquid stream in a first plenum chamber 40 defined by the housing 38, as shown at box 202. The method further comprises draining liquid to a lower portion 42 of the first plenum chamber 40 and through a first drain port 64, as shown at box 203. The method further comprises further separating liquid from the gas-liquid stream in a second plenum chamber 44 defined by the housing 38 and downstream of the first plenum chamber 40, as shown at box 204. The method further comprises draining liquid to a lower portion 46 of the second plenum chamber 44 and through a second drain port 66, as shown at box 205. The method further comprises pumping liquid from the lower portions 42, 46 of the first and second plenum chambers 40, 44 through the first and second drain ports 64, 66, respectively, as shown at box 206.
The method may further comprise pumping liquid from the first and second drain ports 64, 66 into first and second suction ports 84, 86, respectively. The method may further comprise accelerating pressurized fluid through first and second jet orifices 78, 80 and into the first and second suction ports 84, 86, respectively, so as to pump liquid from the lower portions 42, 46 of the first and second plenum chambers 40, 44, respectively. The method may further comprise supplying the pressurized fluid to the first and second jet orifices 78, 80 from a common pressurized fluid source. The method may further comprise mixing the pressurized fluid from the first jet orifice 78 and the liquid from the first drain port 64 with the pressurized fluid from the second jet orifice 80 and the liquid from the second drain port 66 in a common mixing bore 88. In one embodiment, as shown in FIG. 1, the pressurized fluid is oil and the oil is provided from an oil pump 30 coupled to a crankcase 14. In another example, as shown in FIG. 11, the pressurized fluid is air and the air is provided from a turbocharger 126.
In the above description certain terms have been used for brevity, clarity and understanding. No unnecessary limitations are to be inferred therefrom beyond the requirement of the prior art because such terms are used fur descriptive purposes and are intended to be broadly construed. The different assemblies and methods described herein above may be used alone or in combination with other assemblies and methods. Various equivalents, alternatives and modifications are possible within the scope of the appended claims. Each limitation in the appended claims is intended to invoke interpretation under 35 USC §112(f) only if the terms “means for” or “step for” are explicitly recited in the respective limitation. While each of the method claims includes a specific series of steps for accomplishing certain functions, the scope of this disclosure is not intended to be bound by the literal order or literal content of steps described herein, and non-substantial differences or changes still fall within the scope of the disclosure.
Patent Application
20140033922
