Abstract: A passive secondary air muffler for a small internal combustion engine. The secondary air muffler may include a venturi device and a catalytic converter. The venturi device may be in the form of a stamped sheet metal insert which, along with the outer muffler housing or shell, forms a secondary or auxiliary air intake device. The venturi device may also be formed from baffles separating an inlet chamber from an outlet chamber of the muffler. The secondary air intake device provides auxiliary or secondary air to the exhaust gas stream exiting the engine upstream of the catalytic converter to improve the efficiency of the catalytic converter. In an exemplary embodiment, the venturi device has a hemispherical cross-sectional shape or a circular cross-sectional shape taken along a plane substantially perpendicular to the direction of flow of the exhaust gas stream.

Abstract: A passive secondary air muffler for a small internal combustion engine. The secondary air muffler may include a venturi device and a catalytic converter. The venturi device may be in the form of a stamped sheet metal insert which, along with the outer muffler housing or shell, forms a secondary or auxiliary air intake device. The venturi device may also be formed from baffles separating an inlet chamber from an outlet chamber of the muffler. The secondary air intake device provides auxiliary or secondary air to the exhaust gas stream exiting the engine upstream of the catalytic converter to improve the efficiency of the catalytic converter. In an exemplary embodiment, the venturi device has a hemispherical cross-sectional shape or a circular cross-sectional shape taken along a plane substantially perpendicular to the direction of flow of the exhaust gas stream.

Abstract: The present invention provides an evaporative emissions control system for small internal combustion engines. The fuel tank of the engine includes a filler neck closed by a fuel tank cap which seals the fuel tank in a manner in which air and/or fuel vapors are not permitted to pass between the filler neck and the fuel tank cap. The fuel tank cap includes a first, one-way vacuum relief valve therein which operates to allow atmospheric make-up air to enter the fuel tank to replace a decreasing amount of fuel in the fuel tank during running of the engine, or otherwise as needed. The fuel tank cap additionally includes a second, one-way pressure relief valve having a first cracking threshold which operates to relieve high pressures within the fuel tank. Additionally, the fuel supply line between the fuel tank and the carburetor includes a fuel flow inhibiting or blocking member having a second cracking threshold greater than the first cracking threshold of the pressure relief valve of the fuel tank cap.

Abstract: An evaporative emissions control system for small internal combustion engines, including a charcoal canister which is in fluid communication with the air space above the liquid fuel within the carburetor of the engine and the air space above the liquid fuel within the fuel tank of the engine. The charcoal canister contains charcoal media, and when the engine is not running, fuel vapors from the carburetor and the fuel tank migrate to, and are trapped within, the charcoal media of the charcoal canister. The charcoal canister may comprise a separate component, or may be integrally formed with an engine component such as the air cleaner, the carburetor, or the body of the fuel tank, for example. During running of the engine, vacuum within the carburetor induces a flow of atmospheric air through the charcoal canister to purge the collected fuel vapors from the charcoal media, and the fuel vapors pass into the engine for consumption.

Abstract: An evaporative emissions control system for small internal combustion engines. The system generally includes a charcoal canister and a carburetor with a fuel circuit shutoff valve. The charcoal canister is in fluid communication with the air space above the liquid fuel within the engine fuel tank, and optionally, with the air space above the liquid fuel within the fuel bowl of a fuel bowl-type carburetor. The charcoal canister contains charcoal media which absorbs fuel vapors when the engine is not running. During running of the engine, vacuum within the carburetor induces a flow of atmospheric air through the charcoal canister to purge the collected fuel vapors from the charcoal media, and the fuel vapors pass into the engine for consumption. The carburetor of the engine, which may be either a fuel bowl-type carburetor or a diaphragm carburetor, includes a fuel circuit shutoff valve controlled either by a vacuum signal produced within the engine or by a user-actuated mechanical linkage.

Abstract: An exhaust treatment device is provided for an internal combustion engine of a marine propulsion system. An outer chamber contains a first inner chamber within it and slidably supports the inner chamber. An exhaust inlet conduit directs a stream of exhaust gases from a cylinder of the internal combustion engine directly into the inner chamber. The inner and outer chambers are supported relative to each other to allow relative movement of these two components in response to changes in the differential temperature between the two components. A rail system slidably supports the inner chamber relative to the outer chamber. The exhaust treatment device comprises a liquid cooled housing surrounding the inner and outer chambers. Exhaust gas is directed through the inner chamber and then into the outer chamber at a closed end of the exhaust treatment device. Exhaust gases then flow through the outer chamber to an exhaust conduit of the marine propulsion system.