Patent Publication Number: US-2022228544-A1

Title: Induction system including a hydrocarbon trap

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     The present application is a divisional of U.S. Non-Provisional patent application Ser. No. 16/216,820, entitled “INDUCTION SYSTEM INCLUDING A HYDROCARBON TRAP”, and filed on Dec. 11, 2018. The entire contents of the above-listed application are hereby incorporated by reference for all purposes. 
    
    
     FIELD 
     The present description relates generally to methods and systems for including a hydrocarbon trap in the air induction system. 
     BACKGROUND/SUMMARY 
     Evaporative emissions may be caused by fuel vapor escaping from various systems, components, etc., in an engine or other portions of a vehicle. For example, fuel sprayed into an intake manifold, by a fuel injector, may remain on the walls in intake manifold after the engine is shut down and not performing combustion. Consequently, fuel vapor may flow out of the intake system during engine shut down. As a result, evaporative emissions may be increased and in some cases exceed government mandated requirements. Evaporative emissions also have an environmental impact. For example, the emission may create an atmospheric haze when exposed to sunlight. Hydrocarbon (HC) vapor traps are used in the air induction path of internal combustion engines to capture hydrocarbon vapors emanating from within the engine, fuel system, pollution control system, and/or related components, and which would otherwise escape into the environment. 
     Various approaches are provided for incorporating a HC trap in the engine intake system. For example, US 2006/0054142 discloses an intake system with a hydrocarbon trap positioned at a low point in the intake system to capture fuel vapor. A hydrocarbon-adsorptive medium, such as activated carbon may be disposed in a gravitationally low point in the intake air flow passageway between the entrance to the system and the engine. The intake duct itself may be configured to provide the low region for disposition of the medium. Fuel vapors may be absorbed and released from the hydrocarbon trapping medium to reduce evaporative emissions. 
     However, the inventors herein have recognized potential disadvantages with the above approach. As one example, integrated HC adsorbing material such as activated charcoal into a housing of a conduit in the intake system may increase the manufacturing cost of the intake system, as well as reduce the adaptability of the hydrocarbon trap. The direct attachment of the activated carbon to the housing may inhibit the trap from being easily removed, repaired, and/or replaced, and may increase manufacturing costs. Furthermore, the activated carbon may not properly adhere to the housing. As a result, the activated carbon may be released into the intake system and flow downstream into the engine, degrading engine operation. Moreover, the hydrocarbon trap is positioned at a low point in the intake system, thereby constraining the position of the hydrocarbon trap. 
     The inventors herein have recognized that the issues described above may be addressed by a system comprising: a hydrocarbon (HC) pillow-case type trap housed within a rectangular cavity formed in a wall of a cylindrical passage. In this way, by coupling a HC trap to a cavity integrally formed on an air intake system tubular duct, HC trap assembly may be simplified and HC trap efficiency may be improved. 
     In one example, an intake air filter system may include an injection molded duct coupled to a clean air side of an air cleaner box. A cavity or opening may be integrally formed on a side of the wall of the duct, the cavity including a plurality of guiding structures such as finger ribs and alignment pins. A pillow case type HC trap may be positioned via a poke-yoke arrangement within the cavity and then covered with a retention cap. The HC trap may be aligned at an angle relative to the vertical axis of the duct. The cavity may be formed along the length or width of the duct. The duct may include a pair of cavities to house two HC traps. In an alternate embodiment, the pillow-case type HC trap may be housed within a pocket formed within the bore of the duct or on the outer wall of the duct. The HC trap may be slid into a slot formed in the pocket and a protective cap may be placed over the pocket. 
     In this way, by coupling the HC trap to a cavity integrally formed within a wall of the clean air duct via a poke-yoke arrangement, HC trap assembly into the intake air system may be simplified. Due to the poke-yok e arrangement, erroneous positioning of the HC trap may be averted during the assembly. By integrally injection molding locating pins and finger ribs, the HC trap may be installed with fewer components, thereby reducing cost of assembly. Further, the finger ribs and the cavity volume may reduce noise and vibration in the intake air filter system. The technical effect of positioning the HC trap at an angle is that any fluid in the intake system may drain off the HC trap &amp; not form a puddle on the HC Trap. Overall, by using a single linear axis of assembly in the duct of the air filter system to position a HC trap, assembly of the HC trap may be automated with lower possibility of error and improved cost efficiency. 
     It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a schematic depiction of a vehicle including an engine system. 
         FIG. 2  shows a schematic depiction of a vehicle including a fuel delivery system, an induction system having a passive-adsorption hydrocarbon trap, an exhaust system, and the engine of  FIG. 1 . 
         FIG. 3  shows a hydrocarbon (HC) trap assembly coupled to an air induction system. 
         FIGS. 4A-4B  show perspective views of a first embodiment of the HC trap assembly. 
         FIGS. 5A-5F  show the HC trap in the first embodiment of the HC trap assembly. 
         FIGS. 6A-6C  show a cavity for housing the HC trap in the first embodiment of the HC trap assembly. 
         FIG. 7A-7C  show a retention cap placed on a pillow-case type HC trap. 
         FIG. 8A-8B  show the pillow-case type HC trap. 
         FIG. 9A-9B  show a second embodiment of the HC trap assembly shown in  FIG. 2 . 
         FIG. 10A-10B  show a first orientation for a third embodiment of the HC trap assembly shown in  FIG. 2 . 
         FIG. 11A-11B  show a second orientation for the third embodiment of the HC trap assembly shown in  FIG. 2 . 
         FIG. 12A-12D  show a fourth embodiment of the HC trap assembly shown in  FIG. 2 . 
         FIG. 13A-13E  show a fifth embodiment of the HC trap assembly shown in  FIG. 2 . 
         FIG. 14A-14E  show a sixth embodiment of the HC trap assembly shown in  FIG. 2 . 
         FIG. 15A-15D  show a seventh embodiment of the HC trap assembly shown in  FIG. 2 . 
         FIG. 16A-16B  show a protective cap used in the seventh embodiment of the HC trap assembly. 
         FIG. 17A-17D  show an eighth embodiment of the HC trap assembly shown in  FIG. 2 . 
         FIG. 18  shows the air induction system of  FIG. 3  coupled within the engine system of  FIG. 1 . 
         FIGS. 3-18  are drawn to scale, although other relative dimensions may be used, if desired. 
     
    
    
     DETAILED DESCRIPTION 
     The following description relates to systems and methods for a hydrocarbon (HC) trap assembly in the engine intake system. A pillow case-type HC trap may be incorporated in the intake system of an engine system, such as the engine system in  FIG. 1 .  FIG. 2  shows a schematic depiction of a vehicle including the engine system shown in  FIG. 1  and an induction system including the HC trap. An example HC trap assembly may be coupled to the air induction system as shown in  FIG. 3 . Example embodiments of the HC trap assembly and components of the respective embodiments are seen in  FIGS. 4A-17D . 
       FIG. 1  depicts an example of a cylinder  14  of an internal combustion engine  10 , which may be included in a vehicle  5 . Engine  10  may be controlled at least partially by a control system, including a controller  12 , and by input from a vehicle operator  130  via an input device  132 . In this example, input device  132  includes an accelerator pedal and a pedal position sensor  134  for generating a proportional pedal position signal PP. Cylinder (herein, also “combustion chamber”)  14  of engine  10  may include combustion chamber walls  136  with a piston  138  positioned therein. Piston  138  may be coupled to a crankshaft  140  so that reciprocating motion of the piston is translated into rotational motion of the crankshaft. Crankshaft  140  may be coupled to at least one vehicle wheel  55  via a transmission  54 , as further described below. Further, a starter motor (not shown) may be coupled to crankshaft  140  via a flywheel to enable a starting operation of engine  10 . 
     In some examples, the vehicle  5  may comprise an autonomous vehicle and/or a hybrid vehicle with multiple sources of torque available to one or more vehicle wheels  55 . In other examples, vehicle  5  is a conventional vehicle with only an engine or an electric vehicle with only an electric machine(s). In the example shown, vehicle  5  includes engine  10  and an electric machine  52 . Electric machine  52  may be a motor or a motor/generator. Crankshaft  140  of engine  10  and electric machine  52  are connected via transmission  54  to vehicle wheels  55  when one or more clutches  56  are engaged. In the depicted example, a first clutch  56  is provided between crankshaft  140  and electric machine  52 , and a second clutch  56  is provided between electric machine  52  and transmission  54 . Controller  12  may send a signal to an actuator of each clutch  56  to engage or disengage the clutch, so as to connect or disconnect crankshaft  140  from electric machine  52  and the components connected thereto, and/or connect or disconnect electric machine  52  from transmission  54  and the components connected thereto. Transmission  54  may be a gearbox, a planetary gear system, or another type of transmission. 
     The powertrain may be configured in various manners, including as a parallel, a series, or a series-parallel hybrid vehicle. In electric vehicle embodiments, a system battery  58  may be a traction battery that delivers electrical power to electric machine  52  to provide torque to vehicle wheels  55 . In some embodiments, electric machine  52  may also be operated as a generator to provide electrical power to charge system battery  58 , for example, during a braking operation. It will be appreciated that in other embodiments, including non-electric vehicle embodiments, system battery  58  may be a typical starting, lighting, ignition (SLI) battery coupled to an alternator  46 . 
     Alternator  46  may be configured to charge system battery  58  using engine torque via crankshaft  140  during engine running. In addition, alternator  46  may power one or more electrical systems of the engine, such as one or more auxiliary systems including a heating, ventilation, and air conditioning (HVAC) system, electric heater coupled to an electrically heated catalyst (EHC), vehicle lights, an on-board entertainment system, and other auxiliary systems based on their corresponding electrical demands. In one example, a current drawn on the alternator may continually vary based on each of an operator cabin cooling demand, a battery charging requirement, other auxiliary vehicle system demands, and motor torque. A voltage regulator may be coupled to alternator  46  in order to regulate the power output of the alternator based upon system usage requirements, including auxiliary system demands. 
     Cylinder  14  of engine  10  can receive intake air via a series of intake passages  142  and  144  and an intake manifold  146 . Intake manifold  146  can communicate with other cylinders of engine  10  in addition to cylinder  14 . One or more of the intake passages may include one or more boosting devices, such as a turbocharger or a supercharger. For example,  FIG. 1  shows engine  10  configured with a turbocharger, including a compressor  174  arranged between intake passages  142  and  144  and an exhaust turbine  176  arranged along an exhaust passage  135 . Compressor  174  may be at least partially powered by exhaust turbine  176  via a shaft  180  when the boosting device is configured as a turbocharger. However, in other examples, such as when engine  10  is provided with a supercharger, compressor  174  may be powered by mechanical input from a motor or the engine and exhaust turbine  176  may be optionally omitted. In still other examples, engine  10  may be provided with an electric supercharger (e.g., an “eBooster”), and compressor  174  may be driven by an electric motor. 
     An intake air filter system  182  including an air cleaner box may be housed in the air intake passage  142  to remove impurities from intake air reaching the compressor  174 . A pillow case type hydrocarbon (HC) trap  184  may be coupled to a cylindrical passage at the outlet of an air filter system to capture hydrocarbon vapors emanating from within the engine, fuel system, pollution control system, and/or related components, and which would otherwise escape into the environment. A rectangular enclosure may be integrally formed around a rectangular cavity in the wall of the cylindrical passage, the enclosure including a plurality of finger ribs to engage the HC trap in a poke-yoke assembly, and reduce noise and vibration in the engine air induction system. The HC trap may include a flat side surface and two lobes separated by a ridge, the lobes housing a hydrocarbon adsorbent material. The HC trap may be inclined at an angle relative to a vertical axis of the cylindrical passage to reduce fluid accumulation on the surface of the HC trap. Embodiments of an example HC trap assembly  184  is elaborated in relation to  FIGS. 3-17D . In one example, a mass air flow sensor (MAFS)  122  or air Intake temperature sensor (IAT)  122  may be included in the air filter system  182 . By including the HC trap in the air filter system  182 , HC may be effectively adsorbed without a significant effect on airflow and engine power. 
     A throttle  162  including a throttle plate  164  may be provided in the engine intake passages for varying the flow rate and/or pressure of intake air provided to the engine cylinders. For example, throttle  162  may be positioned downstream of compressor  174 , as shown in  FIG. 1 , or may be alternatively provided upstream of compressor  174 . 
     An exhaust manifold  148  can receive exhaust gases from other cylinders of engine  10  in addition to cylinder  14 . An exhaust gas sensor  126  is shown coupled to exhaust manifold  148  upstream of an emission control device  178 . Exhaust gas sensor  126  may be selected from among various suitable sensors for providing an indication of an exhaust gas air/fuel ratio (AFR), such as a linear oxygen sensor or UEGO (universal or wide-range exhaust gas oxygen), a two-state oxygen sensor or EGO, a HEGO (heated EGO), a NOx, a HC, or a CO sensor, for example. In the example of  FIG. 1 , exhaust gas sensor  126  is a UEGO. Emission control device  178  may be a three-way catalyst, a NOx trap, various other emission control devices, or combinations thereof. In the example of  FIG. 1 , emission control device  178  is an electrically heated catalyst (EHC). An electric heater (herein also referred to as a heating element)  179  may be coupled to the EHC  178  to electrically heat the catalyst during cold-start conditions. By actively heating the EHC  178 , catalyst light-off may be expedited, thereby improving emissions quality during cold-start conditions. 
     An exhaust gas recirculation (EGR) delivery passage may be coupled to the exhaust passage upstream of turbine  176  to provide high pressure EGR (HP-EGR) to the engine intake manifold, downstream of compressor  174 . An EGR valve may be coupled to the EGR passage at the junction of the EGR passage and the intake passage. EGR valve may be opened to admit a controlled amount of exhaust to the compressor outlet for desirable combustion and emissions control performance. EGR valve may be configured as a continuously variable valve or as an on/off valve. In further embodiments, the engine system may include a low pressure EGR (LP-EGR) flow path wherein exhaust gas is drawn from downstream of turbine  176  and recirculated to the engine intake manifold, upstream of compressor  174 . 
     Each cylinder of engine  10  may include one or more intake valves and one or more exhaust valves. For example, cylinder  14  is shown including at least one intake valve  150  and at least one exhaust valve  156  located at an upper region of cylinder  14 . In some examples, each cylinder of engine  10 , including cylinder  14 , may include at least two intake valves and at least two exhaust valves located at an upper region of the cylinder. Intake valve  150  may be controlled by controller  12  via an actuator  152 . Similarly, exhaust valve  156  may be controlled by controller  12  via an actuator  154 . The positions of intake valve  150  and exhaust valve  156  may be determined by respective valve position sensors (not shown). 
     During some conditions, controller  12  may vary the signals provided to actuators  152  and  154  to control the opening and closing of the respective intake and exhaust valves. The valve actuators may be of an electric valve actuation type, a cam actuation type, or a combination thereof. The intake and exhaust valve timing may be controlled concurrently, or any of a possibility of variable intake cam timing, variable exhaust cam timing, dual independent variable cam timing, or fixed cam timing may be used. Each cam actuation system may include one or more cams and may utilize one or more of cam profile switching (CPS), variable cam timing (VCT), variable valve timing (VVT), and/or variable valve lift (VVL) systems that may be operated by controller  12  to vary valve operation. For example, cylinder  14  may alternatively include an intake valve controlled via electric valve actuation and an exhaust valve controlled via cam actuation, including CPS and/or VCT. In other examples, the intake and exhaust valves may be controlled by a common valve actuator (or actuation system) or a variable valve timing actuator (or actuation system). 
     In some examples, each cylinder of engine  10  may be configured with one or more fuel injectors for providing fuel thereto. As a non-limiting example, cylinder  14  is shown including a fuel injector  166 . Fuel injector  166  may be configured to deliver fuel received from a fuel system  8 . Fuel system  8  may include one or more fuel tanks, fuel pumps, and fuel rails. Fuel injector  166  is shown coupled directly to cylinder  14  for injecting fuel directly therein in proportion to a pulse width of a signal FPW received from controller  12  via an electronic driver  168 . In this manner, fuel injector  166  provides what is known as direct injection (hereafter also referred to as “DI”) of fuel into cylinder  14 . While  FIG. 1  shows fuel injector  166  positioned to one side of cylinder  14 , fuel injector  166  may alternatively be located overhead of the piston, such as near the position of spark plug  192 . Such a position may increase mixing and combustion when operating the engine with an alcohol-based fuel due to the lower volatility of some alcohol-based fuels. Alternatively, the injector may be located overhead and near the intake valve to increase mixing. Fuel may be delivered to fuel injector  166  from a fuel tank of fuel system  8  via a high pressure fuel pump and a fuel rail. Further, the fuel tank may have a pressure transducer providing a signal to controller  12 . 
     In an alternate example, fuel injector  166  may be arranged in an intake passage rather than coupled directly to cylinder  14  in a configuration that provides what is known as port injection of fuel (hereafter also referred to as “PFI”) into an intake port upstream of cylinder  14 . In yet other examples, cylinder  14  may include multiple injectors, which may be configured as direct fuel injectors, port fuel injectors, or a combination thereof. As such, it should be appreciated that the fuel systems described herein should not be limited by the particular fuel injector configurations described herein by way of example. 
     Each cylinder of engine  10  may include a spark plug  192  for initiating combustion. An ignition system  190  can provide an ignition spark to combustion chamber  14  via spark plug  192  in response to a spark advance signal SA from controller  12 , under select operating modes. A timing of signal SA may be adjusted based on engine operating conditions and driver torque demand. For example, spark may be provided at maximum brake torque (MBT) timing to maximize engine power and efficiency. Controller  12  may input engine operating conditions, including engine speed, engine load, and exhaust gas AFR, into a look-up table and output the corresponding MBT timing for the input engine operating conditions. In other examples, spark may be retarded from MBT, such as to expedite catalyst warm-up during engine start or to reduce an occurrence of engine knock. 
     Controller  12  is shown in  FIG. 1  as a microcomputer, including a microprocessor unit  106 , input/output ports  108 , an electronic storage medium for executable programs (e.g., executable instructions) and calibration values shown as non-transitory read-only memory chip  110  in this particular example, random access memory  112 , keep alive memory  114 , and a data bus. Controller  12  may receive various signals from sensors coupled to engine  10 , including signals previously discussed and additionally including a measurement of inducted mass air flow (MAF) from a mass air flow sensor  122 ; an engine coolant temperature (ECT) from a temperature sensor  116  coupled to a cooling sleeve  118 ; an exhaust gas temperature from a temperature sensor  158  coupled to exhaust passage  135 ; a profile ignition pickup signal (PIP) from a Hall effect sensor  120  (or other type) coupled to crankshaft  140 ; throttle position (TP) from a throttle position sensor; signal UEGO from exhaust gas sensor  126 , which may be used by controller  12  to determine the AFR of the exhaust gas; and an absolute manifold pressure signal (MAP) from a MAP sensor  124 . An engine speed signal, RPM, may be generated by controller  12  from signal PIP. The manifold pressure signal MAP from MAP sensor  124  may be used to provide an indication of vacuum or pressure in the intake manifold. Controller  12  may infer an engine temperature based on the engine coolant temperature and infer a temperature of emission control device  178  based on the signal received from temperature sensor  158 . 
     Controller  12  receives signals from the various sensors of  FIG. 1  and employs the various actuators of  FIG. 1  to adjust engine operation based on the received signals and instructions stored on a memory of the controller. For example, the controller may operate a single pump coupled to two engine valves based on valve timing and a position of the valve to open or close the respective valve. 
     As described above,  FIG. 1  shows only one cylinder of a multi-cylinder engine. As such, each cylinder may similarly include its own set of intake/exhaust valves, fuel injector(s), spark plug, etc. It will be appreciated that engine  10  may include any suitable number of cylinders, including 2, 3, 4, 5, 6, 8, 10, 12, or more cylinders. Further, each of these cylinders can include some or all of the various components described and depicted by  FIG. 1  with reference to cylinder  14 . 
       FIG. 2  shows a vehicle  200  including the engine  10 . The vehicle  200  further includes an induction system  202  configured to supply air to combustion chambers in the engine  10 . Thus, the induction system  202  may draw air from the surrounding environment and provide the air to the engine  10 . Arrow  203  denotes the flow of intake air from the induction system  202  to the engine  10 . The induction system  202  may include various components, such as the throttle  162 , intake manifold  146 , and intake passage  142 ,  144  shown in  FIG. 1 . 
     The vehicle  200  further includes an exhaust system  204  configured to receive exhaust gas from the engine  10 . The exhaust system  204  may include the exhaust manifold  148  and the emission control device  178  shown in  FIG. 1 . It will be appreciated that the exhaust system  204  may receive exhaust gas from the engine  10  and expel the exhaust gas into the surrounding environment. Arrow  205  denotes the flow of exhaust gas from the engine  10  into the exhaust system  204 . 
     The vehicle  200  further includes a fuel delivery system  206  including a fuel tank  208  housing a fuel  210  such as gasoline, diesel, bio-diesel, alcohol (e.g., ethanol, methanol), or a combination thereof. Fuel vapor  212  may also be enclosed in the fuel tank  208 . 
     The fuel delivery system  206  further includes a fuel pump  214  having a pick-up tube  216  extending into the fuel tank  208 . In the depicted example the fuel pump  214  is positioned external to the fuel tank  208 . However, in other examples the fuel pump  214  may be positioned in the fuel tank  208 . 
     A fuel conduit  218 , included in the fuel delivery system  206 , enables fluidic communication between the fuel pump  214  and the engine  10 . Arrow  220  indicates the flow of fuel into the engine  10 . The fuel delivery system  206  may also include valves for regulating the amount of fuel provided to the engine  10 . It will be appreciated that the fuel delivery system  206  may include additional components that are not depicted such as injectors (e.g., direct injectors, port injectors), a higher pressure fuel pump, a fuel rail, etc. 
     The induction system  202  includes at least one induction conduit  222 . The induction conduit  222  may include a hydrocarbon trap  84 . The hydrocarbon trap  84  may be positioned in an air filter system  182  upstream of the throttle  162  shown in  FIG. 1 , in some examples. However, other positions for the passive-adsorption hydrocarbon trap have been contemplated. For example, the hydrocarbon trap  84  may be positioned within the intake manifold  144 , shown in  FIG. 1 . Continuing with  FIG. 2 , the hydrocarbon trap  84  is configured to absorb fuel vapor. In this way, the hydrocarbon trap  84  may reduce the amount of emissions escaping from the induction system  202  when the engine  10  is not performing combustion. 
     The induction conduit  222  is in fluidic communication with the combustion chamber  14  shown in  FIG. 1 . The induction conduit  222  may be positioned upstream of the throttle  162 , in some examples. It will be appreciated that the fuel pump  214  may be controlled via controller  12 . However, in other examples, the fuel pump  214  may be controlled via an internal controller. 
       FIG. 3  shows a first embodiment  300  of a hydrocarbon (HC) trap assembly coupled to an air induction system. The air induction system may include a cuboid shaped air cleaner box  302 . Ambient air may enter the air cleaner box  302  via an intake passage  304  fluidically coupling the engine to the atmosphere. The outlet of the air cleaner box  302  may include a duct (also referred herein as air conduit or cylindrical passage)  306  followed by a passage  310  leading to the engine intake manifold  146 . A throttle or turbocharger inlet may be positioned in the engine intake manifold  146  to regulate the amount of air entering the clean air tube (CAT)  312  of one or more engine cylinders. Air from the air cleaner box  302  may be supplied to intake port  312  via each of the duct  306 , the passage  310 , and the engine clean air tube  312 . 
     The duct  306  may be cylindrical with a uniform cross section. A HC trap system  308  may be coupled to a wall of the duct  306 . The HC trap system  308  may be the HC trap system  84  in  FIGS. 1 and 2 . The HC trap system  84  may be coupled along the circumference of the duct  306 . In this example, the HC trap system  308  may protrude outward from the duct  306  towards the right side of the air cleaner box  302 . However, in alternate arrangements, the HC trap may be coupled in any direction along the wall of the duct  306 . The HC trap may be coupled to the duct  306  in a plurality of arrangements (separate embodiments). A detailed description of a first embodiment of a HC trap system  308  is discussed with relation to  FIGS. 4A-4B . 
       FIG. 4A  shows a side perspective view  400  of a first embodiment of the HC trap system  308  housed in the air induction system and  FIG. 4B  shows a front view  450  of the first HC trap system  308  housed in the air induction system. Components previously introduced in  FIG. 3  are numbered similarly and not reintroduced. 
     A duct  306  comprising a bore may be coupled to the outlet of an air cleaner box  302  of the air induction system  202 . The duct  306  may be injection molded with a hollow rectangular cavity (also referred herein as recess, window, or opening) integrally formed in the wall of the duct. In this way, the cavity may be formed as an integral structure in the duct wall. The cavity may be rectangular, circular, or polygonal with 3 or more sides. A rectangular HC trap  308  may be coupled to the cavity via a poke-yoke arrangement and then covered with a retention cap. The HC trap system  308  may protrude outward from the exterior wall of the duct  306 . 
     The rectangular cavity may be formed at an angle (such as □, as shown in  FIG. 4B ) with respect to a vertical axis A-A′ of the duct. Due to the angled cavity, the HC trap system  308  may form an angle (□) to the vertical axis. In one example, □□ may be 30°. Due to the angled positioning of the HC trap system, water (such as water vapor condensate from ambient air or other fluids) may not accumulate on the HC trap system and may slide off the cap of the HC trap system  308 . Water/fluid accumulation on the HC trap system  308  may have led to increased weight on the HC trap causing structural damage. In this way, by averting water accumulation on the HC trap system  308 , structural and chemical robustness of the HC trap system  308  may be maintained.  FIG. 5A  shows a right side perspective view  500  of the first embodiment of the HC trap system  308  and  FIG. 5B  shows a left side perspective view  520  of the first embodiment of the HC trap system  308 . The HC trap assembly may include a duct  306  positioned at an outlet of an air cleaner box of the air induction system. The HC trap may be pillow case type, flat sheet media type, or other HC Trap media/styles. The outer wall of the duct  306  may include a plurality of concentric ribs  532  along the circumference. Also, a plurality of projections  518 ,  514 , and  516  may protrude out of the outer wall of the duct  306 . The projections  514  and  518  may include holes for fasteners coupling the duct  306  to the air cleaner. The projection  516  and the ribs  532  may facilitate in coupling the duct  306  to the air cleaner box within the air induction system. 
     A cavity (circular, oval, polygonal etc.) may be formed on the right side of the wall of the duct  306  (also referred herein as air conduit or cylindrical passage). An injection molded rectangular enclosure  542  may be positioned around the cavity to hold the HC trap system  308 . The duct  306  along with the enclosure  542  may be integrally part of a single structure without any couplings, the enclosure  542  molded around the cavity. The height of the enclosure  542  may vary across the length of the enclosure with the height being highest at the two ends and the height being lowest at the center of the enclosure. An arcuate first end of the enclosure may be adjoining the wall of the duct  306  (around the cavity) while a second, flat end may be in contact with the HC trap system  308 . The HC trap system  308  may be fixed within the cavity (on the enclosure  542 ) via a poke-yoke arrangement. A plurality of finger ribs  532  and support lands  544  may be formed within the cavity to align and hold the HC trap system  308  within the cavity. 
     The HC trap system  308  may include a pillow-case type trap  510  enclosing HC adsorbent material and a retention cap  502  covering the pillow-case type trap  510 . The structure of the cavity and the enclosure is discussed in details in relation to  FIGS. 6A-6C  and the HC trap system  308  is discussed in details in relation to  FIGS. 7A-7C . 
       FIG. 5C  shows a right view  540  of the first embodiment of the HC trap system  308 . The retention cap  502  includes a rectangular rim  505  along the edge of the cap  502 . Four triangular depressions  503  may be formed on the surface of the cap  502  at the four corners. The rim  505  may be elevated compared to each of the central portion of the cap  502  and the depressions  503  on the cap. 
       FIG. 5D  shows an expanded view  560  of the first embodiment of the HC trap system  308 . In this view, the pillow-case type HC trap  510  and the adjoining retention cap  502  are separated from the cavity  504  formed on the side wall of the duct  306 . A rectangular enclosure  542  may be injection molded on the cavity providing support or clearance for HC trap positioning. In alternate examples, the enclosure may be circular or polygonal with three or more sides. The enclosure  542  may include a rectangular rim  543  around the edge of the enclosure  542 , thereby defining a rectangular opening for HC trap attachment. A plurality of finger ribs  532  may be formed on the side walls of the enclosure  542  to enable engagement of the pillow-case type HC trap  510  within the cavity  504 . The finger ribs may have a range of sizes and shapes. The cavity  504  may include four pins (not shown) located at four corners to enable attachment of the pillow-case type HC trap  510  and the cap  502  inside the cavity  504 . 
     The pillow-case type HC trap  510  may include a shell with two separate lobes filled with a HC adsorbing material such as activated carbon. A wall of the pillow-case type HC trap  510  shell facing the cavity  504  may be formed of a breathable material to allow fluidic communication between the air flowing through the bore  402  of the duct  306  and the HC adsorbing material. The lobes may fit into the central portion of the cap  502  while the cap rim  505  may align with the enclosure rim  543 . Due to the irregular shape of the HC trap  510  and the cap  502 , the components may be coupled in a single unique orientation, thereby eliminating the possibility of erroneous assembly. 
       FIG. 5E  shows a right view  580  of the first embodiment of the HC trap system  308  with the retention cap being removed from the HC trap. The two lobes  513  containing the HC adsorbate material within the pillow-case type HC trap  510  may protrude outward from the cavity holding the HC trap. In one example, the lobes  513  may be asymmetric with each lobe being a 6-sided structure. In another example, the lobes  513  may be symmetric. There may be a ridge formed between the two lobes  513 . In alternate embodiments, there may be one lobe or more than two lobes. There may be four holes  515  along the perimeter or within the flat or curved base of the HC trap to engage with the corresponding pins located at the four corners of the cavity. In one example, the holes may be positioned at the four corners of the HC trap. Since no external fasteners are engaged while attaching the HC trap to the cavity, the assembly process may be simplified and automated. 
       FIG. 5F  shows a cross sectional view  590  of the first embodiment of the HC trap system  308 . The cross section may be taken across the duct and the HC trap  510 . A cross section of the enclosure  542  shows an arcuate first side adjacent to the bore  402  of the duct  306  and a flat second side adjacent to the HC trap  510 . The enclosure may include a rim  543  protruding outward, enclosing the HC trap  510 . The rim may comprise straight walls at right angle to the second side of the enclosure  542 . The cap  502  may be positioned on top of the pillow-case type HC trap with the cap rim  505  positioned directly over the enclosure rim  543 . In this way, the HC trap may be enclosed within the area formed between the enclosure and the cap  502 . The duct  306  and the enclosure  542  may be molded from a single piece, thereby reducing the number on components used in the HC trap assembly. The pillow-case type HC trap  510  may be placed within the u-shaped frame formed by the enclosure  542  and then the trap may be covered by a cap  502  which aligns with the enclosure  542 . 
       FIGS. 6A-6C  show three separate views  600 ,  640 , and  680  of the cavity  504  for housing the HC trap in the first embodiment of the HC trap assembly. In these views the HC traps are not coupled to the duct  306 . An injection molded rectangular enclosure  542  with a rectangular rim  543  may be integrally formed around the cavity (as a single structure) to hold the HC trap system  308 . The rim  543  may have rounded corners. 
     The two opposite long side walls of the enclosure  542  may include a plurality of finger ribs  532  on the inner side of the respective wall. In one example, each wall may include six finger ribs  532  with three on one side and another three on another side with a gap in between. Two lands  544  may be positioned on two opposite short side walls of the enclosure  542 . Each of the two lands may have a rectangular wall facing the ribs  532  and an arcuate wall adjacent to the respective side short wall. The finger ribs may be of unequal height with the ribs closer to the edge being larger than the ribs closer to the center. The ribs may provide stiffness and hold the HC trap within the cavity. In one example, the presence of the finger ribs and cavity volume may reduce noise and vibrations in the intake system. Further, the thickness, volume, and volume partition of the enclosure  542  may be adjusted for acoustic tuning and improvement of noise and vibrations in the intake system. 
       FIG. 7A  shows an outer view  700  (viewed from outside the duct housing the HC trap) of a retention cap  502  placed on a pillow-case type HC trap.  FIG. 7B  shows an inner view  740  (viewed from inside the duct housing the HC trap) of the retention cap  502 .  FIG. 7C  shows a perspective inner view  780  of the retention cap  502 . 
     The outer surface  706  of the cap  502  may include a central portion and four triangular depressions  503  formed on the surface of the cap  502  at the four corners. A rectangular rim  505  with rounded edges may outline the edge of the cap  502 . The rim  505  may be elevated relative to each of the central portion of the cap  502  and the depressions  503  on the outer surface  706  of the cap. 
     When viewed from inside the duct, the inner surface  708  may include four dents  506  at the four corners for engaging the positioning pins (formed on the cavity in which the HC trap is housed) during the poke-yoke assembly of the HC trap within the cavity. Upon coupling of the cap  502  to the HC trap assembly, the pillow-case type HC trap may be positioned in contact with the central portion inner surface  708 . 
     Upon coupling of the HC trap along with the cap to the cavity, ends of each of the four pins may rest (or have a slight clearance to) the four dents  506 . The depressions  503  may allow the cap to be welded on to the HC trap assembly without applying pressure on the pillow-case type HC trap (resting along the center of the inner surface). As an example, the cap may be coupled on top of the pillow-case type HC trap via adhesive thermobonding, heat staking, snap fit, twist lock, rivets, gasket with screw, gasket with snap clips, and/or welding (e.g., ultrasonic welding, hot plate welding, and infrared (IR) welding). In one example, plastic welding may be carried out using a hot plate and infrared weld joint. In the plastic welding method, a weld bead width and a flash trap width may be adjusted based on wall thickness and filler content. The cap may be injection molded, as a separate structure from the HC trap, using a polymeric material, resin such as polypropylene. 
       FIG. 8A  shows a perspective view  800  of a pillow-case type HC trap  510  and  FIG. 8B  shows a top view  850  of the pillow-case type HC trap  510 . The pillow-case type HC trap  510  may include a breathable base surface and two lobes  513  protruding out (from the base) forming a pillow-case type structure. In one example, the breathable base may be flat. In another example, the breathable base may be curved. The breathable base  526  may face the bore of the duct to which the HC trap is coupled while a second surface  527  may be covered by a cap (not shown). Two lobes  513  containing the HC adsorbent material formed on the flat surface  527  may protrude outward away from the cavity holding the HC trap. In one example, there may be one or more lobes and the lobes may protrude outward or inward from the flat or curved surface. There may be a ridge formed between the two lobes  513 . There may be four holes  515  at the four corners of the HC trap to engage with the corresponding pins located at four corners of the cavity or the cap. The breathable surface  526  may face the air flow thorough the duct and the HC adsorbing material inside the two lobes may adsorb any HC from the airstream. The breathable surface  526  may comprise a foam (e.g., open cell foam), a breathable fabric (e.g., non-woven polyester), and/or a carbonized flat sheet media, etc. in some examples. The lobes  513  may be made of a polymeric material, resin such as polypropylene, in some examples. Furthermore, the hydrocarbon adsorption layer may comprise activated carbon, in some examples. 
     The lobes  513  may be coupled to the breathable surface  526  via adhesive thermobonding, heat staking, snap fit, twist lock, rivets, gasket with screw, gasket with snap clips, and/or plastic welding (e.g., ultrasonic welding, hot plate welding, and infrared (IR) welding). Additionally, the hydrocarbon adsorption layer may be coupled to the lobes  513  via an adhesive (e.g., spray adhesive), sew stitching, thermobonding, heat staking, and/or welding (e.g., ultrasonic welding, hot plate welding, IR welding). Coupling the hydrocarbon adsorption layer to the second surface  527  and or breathable surface  526  may reduce the relative motion of the hydrocarbon adsorption layer, thereby decreasing attrition of a loose hydrocarbon adsorption layer. 
     In this way, the HC trap may include a flat, surface with two lobes protruding outward, the singular or plurality of lobes enclosing a hydrocarbon adsorbent material, wherein the flat surface is made of a breathable material allowing fluidic accumulation between the hydrocarbon adsorbent material and fluid passing through the duct. 
       FIG. 9A  shows a perspective view  900  of a second embodiment of the HC trap assembly shown in  FIG. 2  and  FIG. 9B  shows a front view  950  of the second embodiment of the HC trap assembly. In this embodiment, two HC trap systems  308  may be coupled to a single duct  306 . The duct  306  may be at the outlet of an air cleaner box of an engine air induction system. 
     The duct  306  may include two separate cavities integrally molded along the wall each accommodating a HC trap system  308 . Each cavity may include features of cavity  504  as discussed in relation to  FIGS. 6A-6C . Injection molded rectangular enclosures  542  may be structurally formed around each cavity to support the respective HC trap system  308 . Each of the two HC trap systems may include a pillow-case type HC trap (such as HC trap  510  as discussed in detail in relation to  FIGS. 8A-8B ), flat sheet media, or other HC trap media/styles covered by a retaining cap (such as cap  502  as discussed in details in relation to  FIGS. 7A-7C ). 
     In one example, the two HC trap systems  510  may be positioned next to each other. In another example, the two HC trap systems  510  may be positioned on opposite sides of the central bore  402 . In yet another example, more than two HC trap systems may also be attached in series along the wall of the cylindrical duct  306 . 
       FIGS. 10A-10B  show a first orientation  1000  for a third embodiment of the HC trap assembly shown in  FIG. 2 . In this orientation, the long side of the rectangular HC trap system  308  may align along the length of the duct  306  while the short side of the rectangular HC trap system  308  may align with the diameter of the duct  306 . Said another way, the long side of the rectangular HC trap system  308  may be parallel to the central axis X-X′ of the duct  306  while the short side of the rectangular HC trap system  308  may be parallel to the vertical axis A-A′. 
       FIGS. 11A-11B  shows a second orientation  1100  for a third embodiment of the HC trap assembly shown in  FIG. 2 . In this orientation, the short side of the rectangular HC trap system  308  may align along the length of the duct  306  while the long side of the rectangular HC trap system  308  may align with the diameter of the duct  306 . Said another way, the short side of the rectangular HC trap system  308  may be parallel to the central axis X-X′ of the duct  306  while the long side of the rectangular HC trap system  308  may be parallel to the vertical axis A-A′.  FIG. 12A  shows an outer view  1200  (viewed from outside the duct housing the HC trap) of a retention cap placed on a pillow-case type HC trap  510  in a fourth embodiment of the HC trap assembly shown in  FIG. 2 . All features of the retention cap  1212  are the same as that of the retention cap  502  as discussed in  FIGS. 7A-7C  (the common features are numbered similarly and not reiterated) except that the retention cap  1212  may include four pins  1205  at the four corners of the rectangular cap for engaging with corresponding holes in the pillow-case type HC trap during assembly of the HC trap system. 
     The pins  1205  on the cap  1212  may replace the pins present in a cavity of a duct (wherein the HC trap system is coupled) and the cavity may include four corresponding depressions (or holes) into which the pins may be inserted upon assembly of the pillow-case type HC trap and the retention cap  1212  within the cavity of the duct at the outlet of an air cleaner box. The HC trap  510  may be pre-assembled with the retention cap  1212  by using staking, etc. prior to attachment of the HC trap  510  to the duct. 
       FIG. 12B  shows a HC trap system  1220  including a pillow-case type HC trap  510  and a retention cap  1212  in the fourth embodiment of the HC trap assembly. All features of the HC trap  510  are same as that of the HC trap  510  as discussed in  FIGS. 8A-8C  and are not reiterated. The four pins  1205  at the four corners of the retention cap  1212  may be inserted into corresponding holes  515  at the four corners of the rectangular pillow-case type HC trap. Upon assembly, the pins may engage with features such as finger ribs within a cavity of a duct on which the HC trap system may be assembled in a poke-yoke arrangement. 
       FIG. 12C  shows an expanded view  1260  of the fourth embodiment of the HC trap system  308 . In this view, the pillow-case type HC trap  510  and the adjoining retention cap  1212  are separated from the cavity  504  formed on the side wall of the duct  306 . A rectangular enclosure  542  may be injection molded on the cavity providing support for HC trap engagement. The enclosure  542  may include a rectangular rim  543  around the edge of the enclosure  542 , thereby defining a rectangular opening for HC trap attachment. A plurality of finger ribs may be formed on the side walls of the enclosure  542  to enable engagement of the pillow-case type HC trap  510  within the cavity  504 . The dimensions of the finger ribs may vary over a range of sizes and shapes with some ribs being larger and/or wider than others. The retention cap  1212  may include four pins (not shown) located at four corners to enable attachment of the pillow-case type HC trap  510  and the cap  1212  inside the cavity  504 . 
       FIG. 12D  shows a front view  1280  of the cavity  1240  for housing the HC trap in the fourth embodiment of the HC trap assembly. In this view the HC trap system is not coupled to the duct  306 . All features of the cavity  1240  are same as that of the cavity  504  as discussed in  FIGS. 6A-6C  (the common features are numbered similarly and not reiterated) except that the cavity  1240   1212  may not include four pins at the four corners. The pins for engaging the HC trap with the retention cap and the cavity may be present in the four corners of the retention cap instead of the cavity. In this way, a set of pins may be included in either the cavity or the retention cap to engage with corresponding holes housed in the HC trap during assembly of the HC trap system. 
       FIG. 13A  shows a front view  1300  of a fifth embodiment of the HC trap assembly  308  shown in  FIG. 2 .  FIGS. 13B-13C  show perspective views  1320  and  1340  of the fifth embodiment of the HC trap assembly  308  with a first frame arrangement. In this embodiment, the HC trap system  308  is coupled into a pocket formed within a duct  306  at the outlet of an air cleaner box of the engine air induction system. A bore  402  of a duct  306  may be divided into two hollow sections  402   a  (first section) and  402   b  (second section) by an injection molded frame  1303  (also referred herein as a bracket). The frame  1303  may be integrally part of a single structure with the duct  306 . In the first enclosure arrangement, the frame  1303  may include a rectangular upper part  1304  and a rectangular lower part  1305  each coupled to the inner side of the duct  306  wall. The frame  1303  may be parallel to a vertical axis of the duct and may form a chord of the circular bore  402  of the duct  306 . In one example, the first section  402   a  may include 70% of the total area within the bore  402  while the second section  402   b  may include a remaining 30% of the total area within the bore  402 . 
     A HC trap system  308  may be positioned within the upper part  1304  and the lower part  1305  of the frame  1303 . Each of the upper part  1304  and the lower part  1305  may include a u-shaped slot with one end open and another end sealed. A HC trap system  308  may include a pillow-case type HC trap  510  (such as HC trap  510  as discussed in relation to  FIGS. 8A-8B ) and a retention cap  502  (such as retention cap  502  as discussed in relation to  FIGS. 7A-7C ). 
     The HC trap system  308  may be inserted (slid) into the slot formed by each of the upper part  1304  and the lower part  1305  of the frame  1303 . The dimension of the long side of the rectangular HC trap system  308  may be equal to the distance between the upper part  1304  and the lower part  1305  of the frame  1303 . Therefore, upon positioning the HC trap system  308  within the slot, the HC trap system  308  may be snugly held within the bore  402  of the duct  306 . The breathable surface of the pillow-case type HC trap may face the air flow through the first section  402   a  of the duct. While the retention cap  502  (coupled to the HC trap  510 ) may be facing the second section  402   b  of the duct. Alternatively a Flat Sheet or Paper Media may be attached to a frame which may be slid into the slot. 
       FIG. 13D-13E  show perspective views  1360  and  1380  of the fifth embodiment of the HC trap assembly  308  with a second frame arrangement. In the first enclosure arrangement, the frame  1303  may include two separated components, the upper part  1304  and the rectangular lower part  1305  while in the second frame arrangement, the frame  1315  may be a single structure. The frame  1315  may be a C-shaped structure including a lower part coupled or integrally molded to an inner side of the duct  306  wall, an upper part coupled to an inner side of the duct  306  wall, and a connecting arm coupling the lower part and the upper part. Each of the lower part, the connecting arm, and the upper part of the single piece frame  1315  may include an open end and a closed end, thereby forming a u-shaped slot running throughout the frame. Alternatively, the HC trap may be attached or integrally molded to the frame and separately slid in and attached or trapped to the internal bore. 
     The HC trap system  308  may be slid into the slot formed by each of the lower part, the connecting arm, and the upper part of the frame  1315 . The dimension of the long side of the rectangular HC trap system  308  may be equal to the distance between the upper part and the lower part of the frame  1303 . Therefore, upon positioning the HC trap system  308  within the slots, the HC trap system  308  may be inserted into the upper part, the connecting arm, and the lower part of the frame  1315  and the trap may be snugly retained within the bore  402  of the duct  306 . The breathable surface of the pillow-case type HC trap may face the air flow through the first section  402   a  of the duct while the retention cap  502  (coupled to the HC trap  510 ) may be facing the second section  402   b  of the duct. In an alternate embodiment, the breathable surface may be reversed to face the first section  402   a.    
     In this way, a hydrocarbon (HC) pillow-case type trap may be inserted in a slot formed in a frame positioned within a cylindrical bore of a duct of an engine air induction system, the frame and the duct injection molded as a single structure. In a first configuration, the frame may be a two piece structure including an upper part coupled to an inner surface of a wall of the duct and a lower part coupled to an inner surface of a wall of the duct, the slot formed within each of the upper part and the lower part while in a second configuration the frame may be a one piece structure including the upper part coupled to the inner surface of the wall, the lower part coupled to the inner surface of the wall, and a connecting arm joining or integrally molded into the upper part and the lower part, the slot formed within each of the upper part, the lower part, and the connecting arm. 
       FIG. 14A  shows a front view  1400  and  FIG. 14B  shows a rear view  1420  of a sixth embodiment of the HC trap assembly  308  shown in  FIG. 2 .  FIGS. 14C-14E  show perspective views  1440 ,  1460 , and  1480  of the sixth embodiment of the HC trap assembly  308  shown in  FIG. 2 . In this embodiment, the HC trap system  308  is coupled to the inner wall of a duct  306  at the outlet of an air cleaner box of the engine air induction system. At the location of the HC trap system  308 , a bore  402  of a duct  306  may be divided into two sections  403   a  and  403   b  by an integrally formed (injection molded) frame  1406 . The frame  1406  may be part of the duct as a single structure. 
     A first section  403   a  may be hollow allowing flow of air through the duct while the second section  403   b  may be blocked via a shield  1404 . The shield  1404  may cover a D-shaped area formed between the frame  1406  and the wall of the duct  306 . The frame  1406  may be integrally or separately formed as a part of a single structure with the duct  306 . The frame  1406  may be a C-shaped structure including a lower part coupled to an inner side of the duct  306  wall, an upper part coupled to an inner side of the duct  306  wall, and a connecting arm coupling each of the lower part and the upper part. Each of the lower part, the connecting arm, and the upper part of the single piece frame  1406  may include an open end and a closed end, thereby forming a u-shaped slot running throughout the frame. The shield  1404  may extend from the connecting arm of the frame  1406  to the wall of the duct  306 , thereby covering the rear side of the HC trap assembly  308 . The front of the HC trap assembly  308  may remain open allowing air to come in contact with the adsorbent material in the HC trap. 
     The HC trap system  308  may be slid into the slot formed by each of the lower part, the connecting arm, and the upper part of the frame  1406 . The dimension of the long side of the rectangular HC trap system  308  may be equal to the distance between the upper part and the lower part of the frame  1406 . Therefore, upon positioning the HC trap system  308  within the slots, the HC trap system  308  may be inserted into the upper part, the connecting arm, and the lower part of the frame  1406 , and the trap may be snugly held within the bore  402  of the duct  306 . The breathable surface of the pillow-case type HC trap may face the air flow thorough the first section  403   a  of the duct while the retention cap  502  (coupled to the HC trap  510 ) may face the second section  403   b  of the duct. 
     The difference between the fourth embodiment and the fifth embodiment of the HC trap assembly is that in the fourth embodiment, the shield  1404  is absent, thereby making the second section  402   b  hollow whereas in the fifth embodiment, upon coupling of the HC trap system  308  into the frame, an enclosed area (blocked on three sides) may be formed between the HC trap system  308 , the wall of the duct  306 , and the shield  1404 . 
       FIG. 15A  shows a front view  1500  and  FIGS. 15B-15D  show perspective views  1520 ,  1540 , and  1560  of a seventh embodiment of the HC trap assembly shown in  FIG. 2 . In the sixth embodiment, the HC trap system  308  may be coupled to the outer wall of a duct  306  at the outlet of an air cleaner box of the engine air induction system via a frame. A hollow window (also referred herein as side pocket or opening) may be formed on the wall of the duct  306  and the frame  1502  supporting a HC trap system  308  may be coupled to the window  1505  such that the air flowing through the duct is in fluidic communication with the HC trap system  308 . The frame  1502  may be integrally part of a single structure with the duct  306  and the window  1505 . The window may be parallel to a vertical axis of the duct  306 . 
     The frame  1502  may be a three sided structure with the third side housing the HC trap system  308  facing the window  1505  in the duct wall. The first side  1512  and the second side  1514  of the frame  1502  may project outward from the window  1505  and the third side  1516  may vertically connect the first side  1512  and the second side  1514 . There may be a first  1511  step at the junction of the first side  1512  and the third side  1516  and a second step  1513  at the junction of the second arm  1514  and the third side  1516 . A first tab  1521  may be formed within the first step  1511  (on the inner wall) and a second tab  1522  may be formed within the second step  1513  (on the inner wall) to provide a slot for holding the HC trap system  308 . 
     In this way, the frame  1502  may be protruding outward from an outer surface of the wall, the frame including a first side  1512 , a second side  1514 , and a third side  1516 , the first side parallel to the second side and the third side parallel to a vertical axis of the duct, and each of the first side and the second side coupling the third side to the wall. 
     The HC trap system may be positioned in a slot (groove) formed by the first tab  1521 , the second tab  1522 , the first step  1511 , and the second step  1513 . A shield  1532  may cover an area formed between the frame  1502  and the wall of the duct  306  on a first side of the frame while the opposite, second side may be open for access to the HC trap system  308 . The HC trap system  308  may be installed or removed from the second side of the frame. Upon assembly of the HC trap system  308  inside the frame, the second side may be covered via a permanent or detachable protective cap  1504  (also referred herein as protective cap). The protective cap  1504  may be coupled to the frame  1502  via a poke-yoke arrangement. In this way, a detachable or permanently affixed protective cap  1504  may be coupled on a first area between the third side  1516  and the wall on one side of the frame  1502  and an integrally formed shield  1532  covering an area between the third side and the wall on an opposite side of the frame  1502 . Details of the protective cap is discussed with relation to  FIGS. 16A-16B . 
     As discussed before, the HC trap system  308  may include a HC trap  510  (such as HC trap  510  as discussed in relation to  FIGS. 8A-8B ) and a retention cap  1502  (such as retention cap  510  as discussed in relation to  FIGS. 7A-7C ). The HC trap  510  may be a pillow case type trap, flat sheet media, or other HC trap media/style. In this way, the HC trap system  308  may be coupled to the exterior of an air induction system duct via a frame allowing easier assembly. 
     In this way, a system for a HC trap may include a duct coupled to an outlet of an air cleaner box in an engine air induction system, an opening integrally formed on a wall of the duct, a frame injection molded around the opening, and a pillow-case shaped hydrocarbon (HC) trap inserted into a groove formed within the frame. 
       FIG. 16A  shows a front view  1600  and  FIG. 16B  shows a back view  1650  of the protective cap  1504  of the seventh embodiment of the HC trap assembly as shown in  FIG. 15A-15D . The protective cap  1504  may be attached and retained by snapping on, thermobonding, heat staking, twist locking, rivets, gasket with screw, gasket with snap clips, and/or welding (e.g., ultrasonic welding, hot plate welding, and infrared (IR) welding) over a frame coupled to a hollow window (opening) integrally formed in a duct of the air induction system, the frame supporting a HC trap system. The front view shows the outer surface  1621  while the back view shows the inner surface  1622  of the protective cap  1504 . 
     The protective cap  1504  may be rectangular including a first arcuate edge  1614 , a second straight edge  1612 , a third straight edge  1618 , and a fourth straight edge  1616 . The first and the second edge may be longer than each of the third straight edge  1618 , and the fourth straight edge  1616 . The arcuate edge  1614  may be in contact with the curvature of the duct. A first protrusion  1620  and a second protrusion  1622  may project outward from the two ends (along the length of the straight edge  1612 ) of the protective cap  1504 . The height of the protective cap  1504  may be uniform along the arcuate edge  1614  while the height of the protective cap  1504  may taper at both ends along the straight edge. Said another way, each of the first protrusion  1620  and the second protrusion  1622  may have tapering ends. 
     A first finger  1626  may be formed on the inner surface of the first protrusion  1620  and a second finger  1628  may be formed on the inner surface of the second protrusion  1622 . Upon coupling of the protective cap  1504  onto the frame, the inner surface  1622  may face the HC trap system housed within the height. 
       FIG. 17A  shows a front view  1700 ,  FIG. 17B  shows a rear view  1720 , and  FIGS. 17C-17D  shows perspective views  1760  and  1780  of an eighth embodiment of the HC trap assembly shown in  FIG. 2 . In the eighth embodiment, the HC trap system  308  may be coupled to the outer wall of a duct  306  at the outlet of an air cleaner box of the engine air induction system via a frame  1702 . A portion of the wall of the duct  306  may be removed (cutout), and a frame  1702  supporting a HC trap system  308  may be injected molded around the cutout in the duct wall such that the air flowing through the duct is in fluidic communication with the HC trap system  308 . 
     The frame  1702  may be a three sided structure with the third side housing the HC trap system  308  facing the cutout in the duct wall. The first side  1704  and the second side  1706  of the frame  1702  may project outward from the edges of the cutout while the third side  1708  may vertically connect the first side  1704  and the second side  1706 . 
     The frame  1702  may include a short lower vertical wall  1714  (parallel to the third side  1708 ) and a short upper vertical wall  1712  (parallel to the third side  1708 ). In one example, each of the lower vertical wall  1714  and the upper vertical wall  1712  may be a percentage of the length of the third side  1708 . Slots may be formed between the lower vertical wall  1714  and the third side  1708 , and the upper vertical wall  1712  and the third side  1708 . The HC trap system  308  may be slid into the slots formed by each of the lower vertical wall  1714 , the upper vertical wall  1712 , and the third side  1708 . The breathable surface of the pillow-case type HC trap may face the cutout in the duct. 
     A shield  1732  may cover an area formed between the frame  1406  and the wall of the duct  306  on a first side of the frame while the opposite, a second side may be open for access to the HC trap system  308 . The HC trap system  308  may be installed from the second side of the frame. Unlike the sixth embodiment of the HC trap assembly as shown in  15 S.  15 A-D, a protective cap may not be placed over the second side for easy access to the HC trap system  308 . Elimination of the protective cap also simplifies the assembly process by eliminating the manufacturing and attachment of a protective cap to the air conduit. Similar to previous discussed embodiments, the HC trap system  308  may include a HC trap  510  (such as a pillow case type trap, flat sheet media, or other HC trap media/style, the pillow case type trap  510  being discussed in relation to  FIGS. 8A-8B ), and a retention cap  502  (such as retention cap  502  as discussed in relation to  FIGS. 7A-7C ). 
       FIG. 18  shows an example embodiment  1800  of the air induction system of  FIG. 3  coupled within the engine system of  FIG. 1 . The air induction system may include an air cleaner box  302  for purifying air entering the engine system. Ambient air may enter the air cleaner box  302  via an intake passage  304  fluidically coupling the engine system to the atmosphere. The outlet of the air cleaner box  302  may include an air conduit  306  housing a hydrocarbon (HC) trap assembly  308 . In one example, the HC trap assembly  308  may be coupled to a duct of the air induction system, the duct being one of a fresh air inlet tube, filter enclosure, clean air duct etc. 
     The HC trap may be configured to optimize evaporative emissions, air flow, and reduce noise and vibration in the engine air induction system. The HC trap may be pillow case type (with one or more lobed on a flat or curved breathable surface), or sheet media type (flat or curved sheet media with or without frame), or other HC Trap media/styles or combination of types/styles. 
     The air conduit  306  may lead to a turbocharger  1804  including a turbine coupled to an engine exhaust and a compressor coupled to a first engine intake air passage  1806 . A charge air cooler  1805  may be coupled downstream of the turbocharger compressor. An intake duct  1806  may couple the turbocharger compressor to the charge air cooler  1805 . An outlet duct  1807  originating from the charge air cooler  1805  may lead to the throttle body, the engine intake manifold, and the cylinders. Ambient air flowing through the air induction system may be compressed at the turbocharger compressor and then cooled at the charge air cooler  1805  before being delivered to the cylinders for combustion. 
     In this way, a HC trap may be coupled to the inner wall or the outer wall of an air induction system duct via a poke-yoke arrangement to simplify the assembly process (less number of parts) and reduce errors. By inserting the HC trap within a slot formed in a frame supported on the wall of the duct, retention of the HC trap may be simplified. The technical effect of coupling HC traps to windows integrally formed in the wall of the clean air duct is that multiple HC traps may be coupled in a plurality of orientations without adversely affecting airflow through the duct. 
       FIGS. 3-18  show example configurations with relative positioning of the various components. If shown directly contacting each other, or directly coupled, then such elements may be referred to as directly contacting or directly coupled, respectively, at least in one example. Similarly, elements shown contiguous or adjacent to one another may be contiguous or adjacent to each other, respectively, at least in one example. As an example, components laying in face-sharing contact with each other may be referred to as in face-sharing contact. As another example, elements positioned apart from each other with only a space there-between and no other components may be referred to as such, in at least one example. As yet another example, elements shown above/below one another, at opposite sides to one another, or to the left/right of one another may be referred to as such, relative to one another. Further, as shown in the figures, a topmost element or point of element may be referred to as a “top” of the component and a bottommost element or point of the element may be referred to as a “bottom” of the component, in at least one example. As used herein, top/bottom, upper/lower, above/below, may be relative to a vertical axis of the figures and used to describe positioning of elements of the figures relative to one another. As such, elements shown above other elements are positioned vertically above the other elements, in one example. As yet another example, shapes of the elements depicted within the figures may be referred to as having those shapes (e.g., such as being circular, straight, planar, curved, rounded, chamfered, angled, or the like). Further, elements shown intersecting one another may be referred to as intersecting elements or intersecting one another, in at least one example. Further still, an element shown within another element or shown outside of another element may be referred as such, in one example. 
     An example system comprises: a hydrocarbon (HC) trap housed within a cavity formed in a wall of an air conduit of an engine air induction system. In any preceding example, additionally or optionally, the air conduit is an outlet of an air cleaner box in the engine air induction system. In any or all of the preceding examples, additionally or optionally, the HC trap protrudes outward from an outer surface of the wall of the air conduit, the HC trap being one of a pillow-case type or a flat sheet media type. In any or all of the preceding examples, additionally or optionally, the system further comprising, an enclosure integrally formed around the cavity, the enclosure including a plurality of finger ribs and lands to support the HC trap in a symmetrical or poke-yoke assembly. In any or all of the preceding examples, additionally or optionally, the plurality of ribs and lands are formed on an inner wall of the enclosure, the plurality of retention ribs and lands having a distribution of length and thickness. In any or all of the preceding examples, additionally or optionally, the HC trap is covered by a retention cap including one or more rims, depressions, and corners, the HC trap parallel or perpendicular to a central axis of the air conduit. In any or all of the preceding examples, additionally or optionally, the HC trap includes a flat or curved base and one or more lobes positioned on the flat or curved base, the lobes containing a hydrocarbon adsorbent material. In any or all of the preceding examples, additionally or optionally, the system further comprising, one or more of pins located on the cavity or the retention cap. In any or all of the preceding examples, additionally or optionally, the HC trap includes one or more holes on a perimeter of the base to engage with one or more pins during assembly. In any or all of the preceding examples, additionally or optionally, the HC trap is inclined at an angle relative to a vertical or a horizontal axis of the air conduit. In any or all of the preceding examples, additionally or optionally, the system further comprising, two or more HC traps coupled to separate cavities integrally formed on the wall of the air conduit. 
     Another example engine system, comprises: a hydrocarbon (HC) trap inserted in a slot formed in a frame positioned within a bore of an air conduit of an engine air induction system. In any preceding example, additionally or optionally, the frame is a multiple piece structure including an upper part coupled to an inner surface of a wall of the air conduit and a lower part coupled to an inner surface of a wall of the air conduit, the slot formed within each of the upper part and the lower part. In any or all of the preceding examples, additionally or optionally, the frame is a one piece structure including the upper part coupled to the inner surface of the wall, the lower part coupled to the inner surface of the wall with or without a connecting arm joining the upper part and the lower part, the slot formed within each of the upper part, the lower part, and the connecting arm. In any or all of the preceding examples, additionally or optionally, the frame and the air conduit are injection molded as a single structure. In any or all of the preceding examples, additionally or optionally, the HC trap is a pillow-case type trap including a flat or curved surface with one or more lobes protruding outward or inward, the lobes enclosing a hydrocarbon adsorbent material, wherein the flat or curved surface is made of a breathable material allowing fluidic communication between the hydrocarbon adsorbent material and fluid passing through the air conduit. 
     Yet another example engine system, comprises: an air conduit coupled within an engine air induction system, an opening integrally formed in a wall of the air conduit, a frame injection molded around the opening, and a hydrocarbon (HC) trap inserted into a groove formed within the frame. In any preceding example, additionally or optionally, the frame is protruding outward or inward from an outer or inner surface of the wall, the frame including a first side, a second side, and a third side, the first side parallel to the second side and the third side parallel to a vertical or a horizontal axis of the air conduit, and each of the first side and the second side coupling the third side to the wall of the air conduit. In any or all of the preceding examples, additionally or optionally, the groove is formed between a pair of tabs and the third side of the frame, and wherein the HC trap is parallel to the vertical or the horizontal axis of the air conduit with a breathable surface of the HC trap facing the opening, the HC trap covered by a retention cap. In any or all of the preceding examples, additionally or optionally, the system further comprising: a first area between the third side and the wall of the air conduit being covered by a shield on one side of the frame, and a second area between the third side and the wall of the air conduit being open or being covered by a protective cap on an opposite side of the frame. 
     Note that the example control and estimation routines included herein can be used with various engine and/or vehicle system configurations. The control methods and routines disclosed herein may be stored as executable instructions in non-transitory memory and may be carried out by the control system including the controller in combination with the various sensors, actuators, and other engine hardware. The specific routines described herein may represent one or more of any number of processing strategies such as event-driven, interrupt-driven, multi-tasking, multi-threading, and the like. As such, various actions, operations, and/or functions illustrated may be performed in the sequence illustrated, in parallel, or in some cases omitted. Likewise, the order of processing is not necessarily required to achieve the features and advantages of the example embodiments described herein, but is provided for ease of illustration and description. One or more of the illustrated actions, operations and/or functions may be repeatedly performed depending on the particular strategy being used. Further, the described actions, operations and/or functions may graphically represent code to be programmed into non-transitory memory of the computer readable storage medium in the engine control system, where the described actions are carried out by executing the instructions in a system including the various engine hardware components in combination with the electronic controller. 
     It will be appreciated that the configurations and routines disclosed herein are exemplary in nature, and that these specific embodiments are not to be considered in a limiting sense, because numerous variations are possible. For example, the above technology can be applied to V-6, I-4, I-6, V-12, opposed 4, and other engine types. The subject matter of the present disclosure includes all novel and non-obvious combinations and sub-combinations of the various systems and configurations, and other features, functions, and/or properties disclosed herein. 
     As used herein, the term “approximately” is construed to mean plus or minus five percent of the range unless otherwise specified. 
     The following claims particularly point out certain combinations and sub-combinations regarded as novel and non-obvious. These claims may refer to “an” element or “a first” element or the equivalent thereof. Such claims should be understood to include incorporation of one or more such elements, neither requiring nor excluding two or more such elements. Other combinations and sub-combinations of the disclosed features, functions, elements, and/or properties may be claimed through amendment of the present claims or through presentation of new claims in this or a related application. Such claims, whether broader, narrower, equal, or different in scope to the original claims, also are regarded as included within the subject matter of the present disclosure.