Abstract: An exhaust device for an internal combustion engine includes an exhaust manifold including branch pipe portions respectively connected to cylinders of the internal combustion engine in which exhaust strokes are executed at different timings, and a collecting pipe portion to which the branch pipe portions are collected and connected at a downstream side of the branch pipe portions, a catalyst provided at a downstream side of the collecting pipe portion in the exhaust manifold, an exhaust pipe provided at a downstream side of the catalyst, a sensor detecting a state of exhaust gas and provided in the exhaust pipe, and a connecting wall portion connecting the catalyst and the exhaust pipe and extending in a different direction with respect to a first central axis of the catalyst along a flow direction of the exhaust gas.

Abstract: An exhaust manifold muffler having an exhaust manifold portion 10 and a muffler portion 20 integral with the exhaust manifold portion 10. The exhaust manifold portion 10 includes a plurality of manifold pipes 11 having parallel downstream ends which are spaced from each other and are arranged in a row. Each manifold pipe is connected to a respective cylinder of an internal combustion engine such that exhaust presssure pulsations from the manifold pipes operate as reflected waves opposite in phase, so as to damp the pressure pulsations. The muffler portion 20 has a first muffler chamber 22 and a swirl pipe 29 installed in the first muffler chamber 22. The manifold pipes 11 extend tangentially into the first manifold chamber to produce a swirl in the first muffler chamber 22. Part of the swirl enters an upper inlet end of the swirl pipe. The swirl pipe 29 has a lower outlet end which is located between the downstream ends of the manifold pipes 11.