Engine assembly for a vehicle having a hydrocarbon trap

An engine assembly for a vehicle, comprising:

• an internal combustion engine comprising:
• a crankcase;
• a crankshaft disposed at least in part in the crankcase;
• and
• a cylinder block connected to the crankcase,
• the cylinder block defining at least one cylinder, each of the at least one cylinder defining an exhaust port for discharging exhaust gas therefrom;
• and
• an exhaust system for discharging exhaust gas from the engine, the exhaust system defining a first exhaust path and a second exhaust path separate from one another, the exhaust system comprising:
• a catalytic converter in fluid communication with the exhaust port of the at least one cylinder to receive exhaust gas therefrom;
• a main muffler downstream from and in selective fluid communication with the catalytic converter, the main muffler defining at least in part the first exhaust path;
• a hydrocarbon trap downstream from and in selective fluid communication with the catalytic converter, the hydrocarbon trap defining at least in part the second exhaust path, the hydrocarbon trap comprising a hydrocarbon trapping material to adsorb hydrocarbon from exhaust gas flowing therethrough;
• a pre-muffler disposed upstream from the main muffler and the hydrocarbon trap, the pre-muffler defining a pre-muffler chamber, the catalytic converter being in fluid communication with the pre-muffler chamber such that exhaust gas flows from the catalytic converter to the pre-muffler chamber before flowing through one of the first exhaust path and the second exhaust path;
• and
• at least one exhaust path valve operable to selectively obstruct the first exhaust path and the second exhaust path to prevent exhaust gas from the catalytic converter flowing through the first exhaust path and the second exhaust path respectively, the pre-muffler enclosing the at least one exhaust path valve, each of the at least one exhaust path valve being movable between a first exhaust path position and a second exhaust path position,
• the at least one exhaust path valve obstructing the second exhaust path in the first exhaust path position such that exhaust gas flows from the exhaust port of the at least
• one cylinder to the catalytic converter to the main muffler and to the atmosphere, the at least one exhaust path valve obstructing the first exhaust path in the second exhaust path position such that exhaust gas flows from the exhaust port of the at least one cylinder to the catalytic converter to the hydrocarbon trap and to the atmosphere,
• the hydrocarbon trap having an exhaust inlet and an exhaust outlet for receiving and discharging exhaust gas respectively, the hydrocarbon trap comprising:
• a trap housing defining the exhaust inlet and the exhaust outlet of the hydrocarbon trap;
• and
• a sleeve enclosed at least in part by the trap housing, the sleeve housing the hydrocarbon trapping material, the sleeve defining a passage for flow of exhaust gas therethrough as exhaust gas flows from the exhaust inlet to the exhaust outlet of the hydrocarbon trap.

An engine assembly for a vehicle, comprising:

• an internal combustion engine comprising:
• a crankcase;
• a crankshaft disposed at least in part in the crankcase;
• and
• a cylinder block connected to the crankcase,
• the cylinder block defining at least one cylinder, each of the at least one cylinder defining an exhaust port for discharging exhaust gas therefrom;
• and
• an exhaust system for discharging exhaust gas from the engine, the exhaust system defining a first exhaust path and a second exhaust path separate from one another, the exhaust system comprising:
• a catalytic converter in fluid communication with the exhaust port of the at least one cylinder to receive exhaust gas therefrom;
• a main muffler downstream from and in selective fluid communication with the catalytic converter, the main muffler defining at least in part the first exhaust path;
• a hydrocarbon trap downstream from and in selective fluid communication with the catalytic converter, the hydrocarbon trap defining at least in part the second exhaust path, the hydrocarbon trap comprising a hydrocarbon trapping material to adsorb hydrocarbon from exhaust gas flowing therethrough;
• a pre-muffler disposed upstream from the main muffler and the hydrocarbon trap, the pre-muffler defining a pre-muffler chamber, the catalytic converter being in fluid communication with the pre-muffler chamber such that exhaust gas flows from the catalytic converter to the pre-muffler chamber before flowing through one of the first exhaust path and the second exhaust path;
• at least one exhaust path valve operable to selectively obstruct the first exhaust path and the second exhaust path to prevent exhaust gas from the catalytic converter flowing through the first exhaust path and the second exhaust path respectively, the pre-muffler enclosing the at least one exhaust path valve, each of the at least one exhaust path valve being movable between a first exhaust path position and a second exhaust path position,
• the at least one exhaust path valve obstructing the second exhaust path in the first exhaust path position such that exhaust gas flows from the exhaust port of the at least one cylinder to the catalytic converter to the main muffler and to the atmosphere,
• the at least one exhaust path valve obstructing the first exhaust path in the second exhaust path position such that exhaust gas flows from the exhaust port of the at least one cylinder to the catalytic converter to the hydrocarbon trap and to the atmosphere;
• an air intake system fluidly connected to the engine to feed air to the engine;
• and
• a purging conduit fluidly connected to the second exhaust path upstream from the hydrocarbon trap, the purging conduit being fluidly connected to the air intake system to permit air flow from the hydrocarbon trap into the air intake system via the purging conduit.

A method for operating an exhaust system of an engine assembly for a vehicle, the exhaust system defining a first exhaust path and a second exhaust path, the exhaust system comprising:

• a catalytic converter;
• a main muffler downstream from and in selective fluid communication with the catalytic converter, the main muffler defining at least in part the first exhaust path;
• a hydrocarbon trap downstream from and in selective fluid communication with the catalytic converter, the hydrocarbon trap defining at least in part the second exhaust path, the hydrocarbon trap comprising a hydrocarbon trapping material to adsorb hydrocarbon from exhaust gas flowing therethrough;
• an air intake system fluidly connected to the engine to feed air to the engine;
• and
• a purging conduit fluidly connected to the second exhaust path upstream from the hydrocarbon trap, the purging conduit being fluidly connected to the air intake system,
• the method comprising:
• determining at least one operational parameter of the engine assembly;
• selectively obstructing the first exhaust path and the second exhaust path based on the at least one operational parameter of the engine assembly, the first exhaust path being open when the second exhaust path is obstructed, the second exhaust path being open when the first exhaust path is obstructed,
• exhaust gas flowing from the catalytic converter to the main muffler and to the atmosphere in response to the second exhaust path being obstructed,
• exhaust gas flowing from the catalytic converter to the hydrocarbon trap and to the atmosphere in response to the first exhaust path being obstructed;
• obstructing flow through the purging conduit in response to the first exhaust path being obstructed;
• and
• permitting flow through the purging conduit in response to the second exhaust path being obstructed in order to draw ambient air into the second exhaust path via the hydrocarbon trap to provide the air intake system with hydrocarbon purged from the hydrocarbon trap.