Disclosed is a water ingress preventive structure for a tailpipe which discharges exhaust gas outside of a vehicle at a terminal of an exhaust passage system. A curved shape is imparted to the tailpipe. A partition is mounted on an inner periphery of a curved portion outward of a curved direction so as to be gradually spaced apart from the inner periphery toward downstream in a direction of flow of the exhaust gas. Thus, a dead end portion is defined by the partition and the inner periphery of the curved portion outward of the curved direction.

A two-sectioned back-pressured catalytic converter has a main body, a tail tube, and a honeycomb carrier. The honeycomb carrier is mounted securely in the main body and has a first section relatively proximal to the intake opening and a second section relatively proximal to the exhaust opening. The density of the holes of the first section is higher than that of the second section. Therefore, waste gas has sufficient space for expansion when passing through the first section, and thus the pressure and the temperature are both lowered, solving problems of the back pressure and the backward pushing. The tail tube is securely mounted into the main body to form a baffle. The waste gas will hit the baffle after passing the honeycomb carrier and generate turbulence which can slow down the gas and make the gas fully react with the precious metal coating.

An exhaust system for an engine has a volume element such as a muffler or a silencer. First and second exhaust pipes are connected as dual exhaust pipes upstream of or downstream of the volume element. The first exhaust pipe has a first length (L1). A valve is positioned in the second exhaust pipe at a distance (D) from the volume element. The distance D is a fraction of L1 such that the second pipe is a resonator for the first pipe with the valve in a closed position. A method of controlling exhaust noise includes positioning a valve in the first exhaust pipe at a distance (D) from a volume element with D being a specified fraction of a length of the second exhaust pipe, and closing the valve such that the first pipe provides a resonator for the second pipe to counteract standing wave in the second pipe.

In inline four cylinder internal combustion engine (1), exhaust ports for a #2 cylinder and a #3 cylinder merge inside cylinder head (3) and form an opening serving as a single collective exhaust port. Exhaust manifold (5) has individual exhaust pipes (6, 7) for #1 and #4 cylinders and collective exhaust pipe (8), and the leading ends of these three exhaust pipes (6, 7, 8) are connected to catalytic converter (11). Exhaust gas introduction angle (2) of each of individual exhaust pipes (6, 7) is larger by 30-60 degrees than exhaust gas introduction angle (1) of collective exhaust pipe (8). Consequently, flow velocity distribution and temperature distribution in a catalyst carrier become uniform.

A muffler for an exhaust system includes an exhaust gas duct pipe (20) and a wall (26). The wall (26) is connected to the exhaust gas duct pipe (20) in a first connection area (24) thereof by a thread meshing.

An exhaust system for the engine includes two exhaust pipes for discharging therethrough exhaust gases from the engine, a muffler for silencing the exhaust gases, an introducing pipe for introducing the exhaust gases into the muffler and a collecting duct for merging the exhaust gases from the two exhaust pipes together and then to introduce them into the introducing pipe. The collecting duct has a single outlet opening within an interior of the introducing pipe, which single outlet opening has a first passage area that is chosen to be smaller than the sum of respective second passage areas of discharge openings of the exhaust pipes and also to be smaller than a third passage area of the introducing pipe.

An exhaust muffler includes a first muffler section having a tubular member made up of an inner pipe to which an exhaust pipe is connected and an outer pipe covering the inner pipe, and a connector connecting the tubular member and a second muffler section to each other, and the second muffler section having an outer shell, a first partition wall, a second partition wall, and a third partition wall. Exhaust gases delivered from the exhaust pipe are discharged from the first muffler section and the second muffler section out of the exhaust muffler. The second muffler section has a cross-sectional area larger than a cross-sectional area of the tubular member. The exhaust muffler includes a first expansion chamber, a second expansion chamber, and a third expansion chamber. The second muffler section includes a fluid communication pipe extending through the first partition wall and the second partition wall for leading exhaust gases from the first expansion chamber into the second expansion chamber, and an exhaust passage pipe held in fluid communication with the third expansion chamber and extending through the second partition and the third partition wall. The second partition wall has a fluid communication hole defined therein that provides fluid communication between the second expansion chamber and the third expansion chamber. There is thus provided an engine exhaust device capable of increasing a silencing capability by increasing the length of a route through which the exhaust gases flow while maintaining the length of the exhaust device.

An exhaust purification device of a multi-cylinder engine which improves exhaust gas purification performance by substantially uniforming a flow rate of exhaust gas throughout a treatment carrier such as a catalyst and improving dispersibility of the exhaust gas from the multi-cylinder engine to the catalyst and other components in the exhaust purification device wherein two collecting pipes are arranged at substantially symmetric positions across a partition plate part, which has a linear cross sectional shape, and is arranged centrally between the pipes which are each formed into D-shaped cross sectional shapes and comprise a first straight line part, a pair of second straight line parts connected with respective ends of a first straight line part and arranged to be substantially parallel with each other, and a circular arc part that connects ends of a pair of second straight line parts on opposite sides of the first straight line part.

A timbre-scaled exhaust assembly includes: an acoustic portion including an inlet collector including an entrance duct at a first end of the collector in fluid for receiving an exhaust flow from an internal combustion engine and exit ducts at a second end of the collector in fluid communication with a plurality of non-perforated tuning tubes; an outlet collector including entrance ducts in fluid communication with the plurality of non-perforated tuning tubes and an exit duct in fluid communication with an outlet of the exhaust assembly. The inlet collector splits the exhaust flow from the internal combustion engine into the plurality of tuning tubes such that a plurality of distinct exhaust flows pass through the plurality of tuning tubes and the outlet collector combines the exhaust flow. A combined exhaust flow exits the exhaust system through the exhaust tip.

An exhaust muffler is made up of a plurality of layers including an exhaust passage pipe and expansion chambers, and includes a front assembly and a rear assembly sub-assembled separately from the front assembly. The front assembly includes a front exhaust passage pipe, a front muffler body disposed in covering relation to the outside of the front exhaust passage pipe and cooperating with the front exhaust passage pipe in making up double-walled pipes, and an exhaust valve disposed in the front exhaust passage pipe. The rear assembly includes a rear exhaust passage pipe and a rear muffler body disposed in covering relation to the outside of the rear exhaust passage pipe and cooperating with the rear exhaust passage pipe in making up double-walled pipes. There is thus provided an exhaust device for an internal combustion engine in which the accuracy of a position where the exhaust valve is installed is high.