Patent Publication Number: US-2015059713-A1

Title: Intake manifold

Description:
FIELD OF THE DISCLOSURE  
     The present disclosure relates to an intake manifold. More specifically, the present disclosure relates to an intake manifold having a mixing duct that is integrally formed into an EGR flow measurement system. 
     BACKGROUND OF THE DISCLOSURE 
     All engines—diesel, gasoline, propane, and natural gas—produce exhaust gas containing carbon monoxide (CO), hydrocarbons (HC), and nitrous oxides (NO x ). Such emissions are the result of incomplete combustion. In addition, diesel engines also produce particulate matter (PM). As more government focus is being placed on health and environmental issues, agencies around the world are enacting more stringent emission&#39;s laws. Because so many diesel engines are used in trucks, the U.S. Environmental Protection Agency and its counterparts in Europe and Japan first focused on setting emissions regulations for the on-road market. While the worldwide regulation of nonroad diesel engines came later, the pace of cleanup and rate of improvement has been more aggressive for nonroad engines than for on-road engines. 
     Manufacturers of nonroad diesel engines are expected to meet set emissions regulations. For example, Tier 3 emissions regulations required approximately a 65 percent reduction in PM and a 60 percent reduction in NO x  from 1996 levels. As a further example, Interim Tier 4 regulations required a 90 percent reduction in PM along with a 50 percent drop in NO x . Still further, Final Tier 4 regulations, which will be fully implemented by 2015, will take PM and NO x  emissions to near-zero levels. 
     An engine may have an EGR system for recirculating a portion of the engine&#39;s exhaust gas back to an intake manifold. This portion of the exhaust gas is commonly referred to as recirculated exhaust gas and is useful for reducing the concentration of oxygen available for combustion, thus lowering the combustion temperatures, slowing reactions, and decreasing NO x  formations. While, as just mentioned, recirculated exhaust gas means the exhaust gas that is recirculated into the engine, fresh intake gas, conversely, means the gas that is entering the power system from the atmosphere. In some cases, the intake manifold needs to supply a precise ratio of recirculated exhaust gas to fresh intake gas, because too small of a ratio may cause an increase in NO x  emissions, while too large of a ratio may cause an increase in soot emissions. To achieve both low NO x  emissions and soot emissions simultaneously, it is important that the ratio of the recirculated exhaust gas flow to fresh intake gas flow be optimized, and that also the ratio be consistent amongst all of the engine&#39;s cylinders. 
     SUMMARY OF THE DISCLOSURE 
     Disclosed is an intake manifold, the intake manifold having an intake gas duct, an EGR duct, an EGR flow measurement system, and a mixing duct. The intake gas duct allows the fresh intake gas to flow therethrough. The EGR flow measurement system defines a portion of an EGR duct and measures a differential pressure of the recirculated exhaust gas passing through the EGR flow measurement system. The mixing duct is positioned downstream of the intake gas duct, and it is also positioned downstream of the EGR duct. The mixing duct mixes the fresh intake gas and the recirculated exhaust gas into a mixed intake gas. The mixing duct is integrally formed into the EGR flow measurement system. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The detailed description of the drawings refers to the accompanying figures in which: 
         FIG. 1 . is a diagrammatic view of a power system having an intake manifold; 
         FIG. 2  is a perspective view of the power system and the intake manifold; 
         FIG. 3  is a sectional view of the intake manifold taken along lines  3 - 3  of  FIG. 2  showing a venturi insert and a EGR flow measurement system; 
         FIG. 4  is a perspective view of the venturi insert; 
         FIG. 5  is a perspective view of a second embodiment of an intake manifold; 
         FIG. 6  is a sectional view of the second embodiment of the exhaust gas recirculation mixer taken along lines  6 - 6  of  FIG. 5  showing an orifice insert; and 
         FIG. 7  is a perspective view of the orifice insert with portions broken away showing a high pressure section, a low pressure section, and an orifice. 
     
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS 
     Referring to  FIG. 1 , there is shown a schematic illustration of a power system  100  for providing power to a variety of machines, including on-highway trucks, construction vehicles, marine vessels, stationary generators, automobiles, agricultural vehicles, and recreation vehicles. 
     The engine  106  may be any kind of engine  106  that produces an exhaust gas, the exhaust gas being indicated by directional arrow  192 . For example, engine  106  may be an internal combustion engine, such as a gasoline engine, a diesel engine, a gaseous fuel burning engine (e.g., natural gas) or any other exhaust gas producing engine. The engine  106  may be of any size, with any number cylinders (not shown), and in any configuration (e.g., “V,” inline, and radial). Although not shown, the engine  106  may include various sensors, such as temperature sensors, pressure sensors, and mass flow sensors. 
     The power system  100  may include an intake system  107  for introducing a fresh intake gas, indicated by directional arrow  189 , into the engine  106 . For example, the intake system  107  may include an intake manifold  128  in communication with the cylinders, a compressor  112 , a charge air cooler  116 , and an air throttle actuator  126 . 
     The compressor  112  may be a fixed geometry compressor, a variable geometry compressor, or any other type of compressor for receiving the fresh intake gas, from upstream of the compressor  112 . The compressor  112  compress the fresh intake gas to an elevated pressure level. As shown, the charge air cooler  116  is positioned downstream of the compressor  112 , and is configured to cool the fresh intake gas. 
     The air throttle actuator  126  may be positioned downstream of the charge air cooler  116 , and it may be, for example, a flap type valve controlled by an electronic control unit (ECU)  115  to regulate the air-fuel ratio. The air throttle actuator  126  is open during normal operation and when the engine  106  is off. However, in order to raise the exhaust temperature prior to and during active exhaust filter regeneration, the ECU  115  progressively closes the air throttle actuator  126  (or, in some embodiments, an exhaust throttle valve). This creates a restriction and the exhaust temperature goes up. The ECU  115  receives position feedback from an internal sensor within the air throttle actuator  126 . 
     Further, the power system  100  may include an exhaust system  140  having components for directing exhaust gas from the engine  106  to the atmosphere. Specifically, the exhaust system  140  may include an exhaust manifold (not shown) in fluid communication with the cylinders. During an exhaust stroke, at least one exhaust valve (not shown) opens, allowing the exhaust gas to flow through the exhaust manifold and a turbine  111 . The pressure and volume of the exhaust gas drives the turbine  111 , allowing it to drive the compressor  112  via a shaft (not shown). The combination of the compressor  112 , the shaft, and the turbine  111  is known as a turbocharger  108 . 
     In some embodiments, the power system  100  may also include a second turbocharger  109  that cooperates with the turbocharger  108  (e.g., parallel turbocharging or, as shown, series turbocharging). The second turbocharger  109  includes a second compressor  114 , a second shaft (not shown), and a second turbine  113 . The second compressor  114  may be a fixed geometry compressor, a variable geometry compressor, or any other type of compressor for receiving the fresh intake gas, from upstream of the second compressor  114 , and compress the fresh intake gas to an elevated pressure level before it enters the engine  106 . 
     The power system  100  may also include an EGR system  132  for receiving a recirculated portion of the exhaust gas, as indicated by directional arrow  194 . The intake gas is indicated by directional arrow  190 , and it is a combination of the fresh intake gas and the recirculated portion of the exhaust gas. The EGR system  132  has an EGR cooler  118  and an EGR valve  122 . The EGR valve  122  may be a vacuum controlled valve or an electrically actuated valve, so as to allow a specific amount of the recirculated portion of the exhaust gas back into the intake manifold  128 . The EGR cooler  118  cools the recirculated portion of the exhaust gas flowing therethrough. Although the EGR valve  122  is illustrated as being downstream of the EGR cooler  118 , it could also be positioned upstream of the EGR cooler  118 . 
     As further shown, the exhaust system  140  may include an aftertreatment system  120 , and at least a portion of the exhaust gas passes therethrough. The aftertreatment system  120  removes various chemical compounds and particulate emissions present in the exhaust gas received from the engine  106 . After being treated by the aftertreatment system  120 , the exhaust gas is expelled into the atmosphere via a tailpipe  124 . 
     The aftertreatment system  120  may include a NO x  sensor  119  for producing and transmitting a NO x  signal to the ECU  115  that is indicative of a NO x  content of exhaust gas flowing thereby. The NO x  sensor  119  may, for example, rely upon an electrochemical or catalytic reaction that generates a current, the magnitude of which is indicative of the NO x  concentration of the exhaust gas. 
     The ECU  115  may have four primary functions: (1) converting analog sensor inputs to digital outputs, (2) performing mathematical computations for all fuel and other systems, (3) performing self diagnostics, and (4) storing information. The ECU  115  may, in response to the NO x  signal, control a combustion temperature of the engine  106  and/or the amount of a reductant injected into the exhaust gas, so as to minimize the level of NO x  entering the atmosphere. 
     In the illustrated embodiment, the aftertreatment system  120  includes a diesel oxidation catalyst (DOC)  163 , a diesel particulate filter (DPF)  164 , and a selective catalytic reduction (SCR) system  152 . The SCR system  152  includes a reductant delivery system  135 , an SCR catalyst  170 , and an ammonia oxidation catalyst (AOC)  174 . The exhaust gas may flow through the DOC  163 , the DPF  164 , the SCR catalyst  170 , and the AOC  174 , and is then, as just mentioned, expelled into the atmosphere via the tailpipe  124 . 
     In other words, in the embodiment shown, the DPF  164  is positioned downstream of the DOC  163 , the SCR catalyst  170  downstream of the DPF  164 , and the AOC  174  downstream of the SCR catalyst  170 . The DOC  163 , the DPF  164 , the SCR catalyst  170 , and the AOC  174  may be coupled together. Exhaust gas treated, in the aftertreatment system  120 , and released into the atmosphere contains significantly fewer pollutants—such as diesel particulate matter, NO 2 , and hydrocarbons—than an untreated exhaust gas. 
     The DOC  163  may contain catalyst materials useful in collecting, absorbing, adsorbing, and/or converting hydrocarbons, carbon monoxide, and/or oxides of nitrogen contained in the exhaust gas. Such catalyst materials may include, for example, aluminum, platinum, palladium, rhodium, barium, cerium, and/or alkali metals, alkaline-earth metals, rare-earth metals, or combinations thereof. The DOC  163  may include, for example, a ceramic substrate, a metallic mesh, foam, or any other porous material known in the art, and the catalyst materials may be located on, for example, a substrate of the DOC  163 . The DOC(s) may also oxidize NO contained in the exhaust gas, thereby converting it to NO 2 . Or, stated slightly differently, the DOC  163  may assist in achieving a desired ratio of NO to NO 2  upstream of the SCR catalyst  170 . 
     The DPF  164  may be any of various particulate filters known in the art for reducing particulate matter concentrations, e.g., soot and ash, in the exhaust gas to meet requisite emission standards. Any structure capable of removing particulate matter from the exhaust gas of the engine  106  may be used. For example, the DPF  164  may include a wall-flow ceramic substrate having a honeycomb cross-section constructed of cordierite, silicon carbide, or other suitable material to remove the particulate matter. The DPF  164  may be electrically coupled to a controller, such as the ECU  115 , that controls various characteristics of the DPF  164 . 
     If the DPF  164  were used alone, it would initially help in meeting the emission requirements, but would quickly fill up with soot and need to be replaced. Therefore, the DPF  164  is combined with the DOC  163 , which helps extend the life of the DPF  164  through the process of regeneration. The ECU  115  may measure the PM build up, also known as filter loading, in the DPF  164 , using a combination of algorithms and sensors. When filter loading occurs, the ECU  115  manages the initiation and duration of the regeneration process. 
     Moreover, the reductant delivery system  135  may include a reductant tank  148  for storing the reductant. One example of a reductant is a solution having 32.5% high purity urea and 67.5% deionized water (e.g., DEF), which decomposes as it travels through a decomposition tube  160  to produce ammonia. Such a reductant may begin to freeze at approximately 12 deg F. (−11 deg C.). If the reductant freezes when a machine is shut down, then the reductant may need to be thawed before the SCR system  152  can function. 
     The reductant delivery system  135  may include a reductant header  136  mounted to the reductant tank  148 , the reductant header  136  further including, in some embodiments, a level sensor  150  for measuring a quantity of the reductant in the reductant tank  148 . The level sensor  150  may include a float for floating at a liquid/air surface interface of reductant included within the reductant tank  148 . Other implementations of the level sensor  150  are possible, and may include, for example, one or more of the following: (a) using one or more ultrasonic sensors; (b) using one or more optical liquid-surface measurement sensors; (c) using one or more pressure sensors disposed within the reductant tank  148 ; and (d) using one or more capacitance sensors. 
     In the illustrated embodiment, the reductant header  136  include a tank heating element  130  for receiving coolant from the engine  106 , and the power system  100  may include a cooling system  133  that includes a coolant supply passage  180  and a coolant return passage  181 . A first segment  196  of the coolant supply passage  180  is positioned fluidly between the engine  106  and the tank heating element  130 , and supplies coolant to the tank heating element  130 . The coolant circulates, through the tank heating element  130 , so as to warm the reductant in the reductant tank  148 , therefore reducing the risk that the reductant freezes therein. In an alternative embodiment, the tank heating element  130  may, instead, be an electrically resistive heating element. 
     A second segment  197  of the coolant supply passage  180  is positioned fluidly between the tank heating element  130  and a reductant delivery mechanism  158 , and supplies coolant thereto. The coolant heats the reductant delivery mechanism  158 , reducing the risk that reductant freezes therein. 
     A first segment  198  of the coolant return passage  181  is positioned between the reductant delivery mechanism  158  and the tank heating element  130 , and a second segment  199  of the coolant return passage  181  is positioned between the engine  106  and the tank heating element  130 . The first segment  198  and the second segment  199  return the coolant to the engine  106 . 
     The decomposition tube  160  may be positioned downstream of the reductant delivery mechanism  158 , but upstream of the SCR catalyst  170 . The reductant delivery mechanism  158  may be, for example, an injector that is selectively controllable to inject reductant directly into the exhaust gas. As shown, the SCR system  152  may include a reductant mixer  166  that is positioned upstream of the SCR catalyst  170  and downstream of the reductant delivery mechanism  158 . 
     The reductant delivery system  135  may additionally include a reductant pressure source (not shown) and a reductant extraction passage  184 . The reductant extraction passage  184  may be coupled fluidly to the reductant tank  148  and the reductant pressure source therebetween. Although the reductant extraction passage  184  is shown extending into the reductant tank  148 , in other embodiments, the reductant extraction passage  184  may be coupled to an extraction tube via the reductant header  136 . The reductant delivery system  135  may further include a reductant supply module  168 , and it may include the reductant pressure source. The reductant supply module  168  may be, or be similar to, a Bosch reductant supply module, such as the one found in the “Bosch Denoxtronic 2.2—Urea Dosing System for SCR Systems.” 
     The reductant delivery system  135  may also include a reductant dosing passage  186  and a reductant return passage  188 . The reductant return passage  188  is shown extending into the reductant tank  148 , though in some embodiments of the power system  100 , the reductant return passage  188  may be coupled to a return tube via the reductant header  136 . And the reductant delivery system  135  may include—among other things—valves, orifices, sensors, and pumps positioned in the reductant extraction passage  184 , reductant dosing passage  186 , and reductant return passage  188 . 
     As mentioned above, one example of a reductant is a solution having 32.5% high purity urea and 67.5% deionized water (e.g., DEF), which decomposes as it travels through the decomposition tube  160  to produce ammonia. The ammonia reacts with NO x  in the presence of the SCR catalyst  170 , and it reduces the NO x  to less harmful emissions, such as N 2  and H 2 O. The SCR catalyst  170  may be any of various catalysts known in the art. For example, in some embodiments, the SCR catalyst  170  may be a vanadium-based catalyst. But in other embodiments, the SCR catalyst  170  may be a zeolite-based catalyst, such as a Cu-zeolite or a Fe-zeolite. 
     The AOC  174  may be any of various flowthrough catalysts reacts with ammonia to produce mainly nitrogen. Generally, the AOC  174  is utilized to remove ammonia that has slipped through or exited the SCR catalyst  170 . As shown, the AOC  174  and the SCR catalyst  170  may be positioned within the same housing. But in other embodiments, they may be separate from one another. 
     Referring to  FIGS. 2-4 , the intake manifold  128  includes a fresh intake gas opening  173 , an EGR flow measurement system  137 , and a mixing duct  139 . The fresh intake gas opening  173  allows the fresh intake gas to flow therethrough. An intake gas duct  131  may be mounted to the intake manifold  128 , or it may be formed integrally thereto. The EGR flow measurement system  137  defines a portion of an EGR duct  141  and measures a differential pressure of the recirculated exhaust gas flowing therethrough, which may be used for calculating, for example, the flow rate thereof. An additional EGR duct  155  may be positioned fluidly between the EGR valve  122  and the intake manifold  128 . 
     The mixing duct  139  is positioned downstream of the fresh intake gas opening  173  relative to a direction of the fresh intake gas flow, and is also positioned downstream of the EGR duct  141  relative to a direction of the recirculated exhaust gas flow. The mixing duct  139 , which is integrally formed into the EGR flow measurement system  137 , mixes the fresh intake gas and the recirculated exhaust gas into a mixed intake gas. The recirculated exhaust gas travels in pulses correlating to the exhaust strokes of the cylinders (not shown) of the engine  106 . So, if the engine  106  has, for example, four cylinders, then the recirculated exhaust gas travels in one pulse per every 180° of crank rotation. The fresh intake gas also travels in pulses, but these pulses correlate to, for example, the operation of the turbocharger  108  and the second turbocharger  109  and intake valves (not shown), resulting in the pulses of the fresh intake gas flow at unique times and frequencies relative to the pulses of the recirculated exhaust gas. As a result of all of this, the recirculated exhaust gas and fresh intake gas turbulently mix in the mixing duct  139 . 
     To do this, the mixing duct  139  may include a mixing cylinder insert  129  having a plurality of mixing passages  138 , the mixing passages  138  being positioned so as to create cross streams of the recirculated exhaust gas for mixing with the fresh intake gas. The combination of the mixing duct  139  and the mixing cylinder insert  129  may be referred to as an EGR mixer. The mixed intake gas is, ultimately, combusted in the engine  106 . The integration of the mixing duct  139  and the EGR flow measurement system  137  results in a compact, reliable, sealed design. 
     As illustrated in  FIG. 3 , the EGR flow measurement system  137  may have a converging section  144  and a diverging section  146  positioned downstream thereof, the converging section  144  and the diverging section  146  defining a connection  154 . The EGR flow measurement system  137  further includes a high pressure passage  156  and a low pressure passage  157 , both being, for example, drilled passages. A first end  161  of the high pressure passage  156  is connected to one of the converging section  144  and the connection  154 , and a first end  162  of the low pressure passage  157  is connected to one of the connection  154  and the diverging section  146 . 
     As shown in  FIGS. 304 , a venturi insert  142  may define the converging section  144  and the diverging section  146 . The diverging section  146  defines an exit angle between, for example, 30° and 90° relative to a longitudinal axis  151  of the EGR flow measurement system  137 . Further, as shown in the illustrated embodiment, it may define a portion of the high pressure passage  156  and a portion of the low pressure passage  157 . 
     The venturi insert  142  may be formed of stainless steel or aluminum, for example, and may need to be carefully shaped and machined so as to ensure accurate differential pressure readings of the recirculated exhaust gas flow. The venturi insert  142  may be positioned via a lost foam casting process. 
     Further, the venturi insert  142  may define a coolant passage  165 , the coolant passage  165  being positioned between the high pressure passage  156  and the low pressure passage  157 . The coolant passage  165  stabilizes the temperature of the EGR flow measurement system  137 , so as to prevent the formation of condensation. A cover  167  is welded to the intake manifold  128  so as to seal it. 
     In the power system  100 , when the EGR valve  122  is open, exhaust gas flows through the EGR cooler  118 , through the EGR valve  122 , through the EGR flow measurement system  137 , and through the intake manifold  128 . And more particularly, as the recirculated exhaust gas flows through the EGR flow measurement system  137 , it flows through the venturi insert  142 . The EGR flow measurement system  137  measures the recirculated exhaust gas differential pressure on an accurate and dynamic basis, and it then forwards the measurement to the ECU  115 . 
     As shown in  FIG. 3 , the EGR flow measurement system  137  may include a differential pressure sensor  172  that is positioned fluidly between a second end  175  of the high pressure passage  156 , and a second end  177  of the low pressure passage  157 . As shown, the differential pressure sensor  172  may be mounted to the venturi insert  142 , but in other embodiments, it may be mounted to the intake manifold  128 . A sensor cover  178  and the differential pressure sensor  172  may be mounted via a pair of fasteners  153 . 
     The differential pressure sensor  172  measures a differential pressure between a portion of the recirculated exhaust gas that is positioned at the connection  154  or upstream thereof, and a portion of the recirculated exhaust gas that is positioned at the connection  154  or downstream thereof. The differential pressure sensor  172  may be, for example, a P321 Kavlico Differential Pressure Sensor. The P321 Kavlico Differential Pressure Sensor may use a 5 Vdc input to measure the differential pressure, between the high pressure passage  156  and the low pressure passage  157 , providing a 0.5 to 4.5 Vdc output proportional to pressure. Incorporating an oil-filled capacitive sense element, such a sensor may be able to withstand vacuum (negative) pressures as well as high common mode pressures. In addition to the differential pressure sensor  172 , an EGR temperature sensor  159  may be positioned, in the intake manifold  128 , for measuring the temperature of the recirculated exhaust gas. More particularly, the EGR temperature sensor  159  may be positioned in an EGR temperature sensor port  169  of the venturi insert  142 . 
     Referring to  FIGS. 4-7 , there is shown a second embodiment of an intake manifold  228  for mixing the fresh intake gas and the recirculated exhaust gas. The intake manifold  228  has several components similar in structure and function as the intake manifold  128 , as indicated by the use of identical reference numerals where applicable. The intake manifold  228  includes a second embodiment of an EGR flow measurement system  237  and a second embodiment of a mixing duct  239 . The intake manifold  228  may include a plurality of mixing passages  238 , the mixing passages  238  being positioned so as to create cross streams of the recirculated exhaust gas that mix with the fresh intake gas. 
     The EGR flow measurement system  237  may include an orifice insert  243 , a high pressure passage  156 , and a low pressure passage  157 . The orifice insert  243  includes a high pressure section  245 , a low pressure section  247 , and an orifice  249 —the high pressure section  245  being positioned upstream of the low pressure section  247 , and the orifice  249  being positioned therebetween. A first end  161  of the high pressure passage  156  is connected to the high pressure section  245 , while a first end  162  of the low pressure passage  157  is connected to the low pressure section  247 . 
     As shown in  FIGS. 5-6 , a cover  167  may be welded to the intake manifold  228 . Further, the EGR flow measurement system  137  includes a differential pressure sensor  172  positioned fluidly between a second end  175  of the high pressure passage  156 , and a second end  177  of the low pressure passage  157 . The differential pressure sensor  172  is mounted to the orifice insert  243 . 
     Finally, as shown in  FIG. 7 , the orifice insert  243  may define a portion of the high pressure passage  156  and a portion of the low pressure passage  157 . In the embodiment shown, the orifice  249  is a diverging orifice that increases in diameter in a downstream direction. The orifice insert  243 , which may be positioned via a lost foam casting process, may be formed out of stainless steel or aluminum and may need to be carefully shaped and machined so as to ensure accurate pressure readings of the recirculated exhaust gas. The orifice insert  243  may define a portion of a coolant passage  265 , the coolant passage  265  being positioned between the high pressure passage  156  and the low pressure passage  157 . The coolant passage  265  stabilizes the temperature of the EGR flow measurement system  237 , thereby preventing the formation of condensation. 
     While the disclosure has been illustrated and described in detail in the drawings and foregoing description, such illustration and description is to be considered as exemplary and not restrictive in character, it being understood that illustrative embodiments have been shown and described and that all changes and modifications that come within the spirit of the disclosure are desired to be protected. It will be noted that alternative embodiments of the present disclosure may not include all of the features described yet still benefit from at least some of the advantages of such features. Those of ordinary skill in the art may readily devise their own implementations that incorporate one or more of the features of the present disclosure and fall within the spirit and scope of the present invention as defined by the appended claims.