Abstract: An apparatus for an exhaust gas system includes a main exhaust passage, a main catalytic converter disposed in the main exhaust passage, a bypass exhaust passage, a bypass catalytic converter disposed in the bypass exhaust passage, and a valve configured to open or close a section of the main exhaust passage. The bypass exhaust passage bypasses the main exhaust passage between a branch point of the bypass exhaust passage out of the main exhaust passage and a junction with the main exhaust passage at a upstream side of the main catalytic converter. A first sensor indicates a first air-fuel ratio of exhaust gas in the bypass exhaust passage. A second sensor indicates a second air-fuel ratio of exhaust gas flowing into the main catalytic converter. A controller determines whether the valve in the closed configuration leaks exhaust gas based on the first and second air-fuel ratios of exhaust gas.

Abstract: An exhaust gas cleaning apparatus is provided that has a main exhaust passage, a main catalytic converter disposed in the main exhaust passage, a bypass exhaust passage, a bypass catalytic converter disposed in the bypass exhaust passage, a selector valve and a controller. The controller controls the internal combustion engine to a rich combustion state with a rich air fuel ratio while the controller controls the selector valve to block the flow of the exhaust gas through the main exhaust passage, and then, afterwards, controls the selector valve to direct the flow of the exhaust gas through the main exhaust passage such that residual air remaining in the main exhaust passage mixes with rich exhaust gas from the bypass exhaust passage.

Abstract: An exhaust system of the internal combustion engine comprises upstream main paths for cylinders that are attached to a side of a cylinder head and extend towards a side of the engine, and are connected to the respective cylinders; a downstream main path in which the upstream main paths join so as to become one flow path; a main catalytic converter provided on the downstream main path; bypasses that are split from the upstream main paths or the downstream main path; a bypass catalytic converter that is provided on the bypass; and flow path switching valves that open and close the upstream main paths so that exhaust discharged from the cylinders flows into the bypass. The bypass catalytic converter is provided below the upstream main paths.

Abstract: An exhaust gas cleaning apparatus is provided that has a main exhaust passage, a main catalytic converter disposed in the main exhaust passage, a bypass exhaust passage, a bypass catalytic converter disposed in the bypass exhaust passage, a selector valve and a controller. The controller controls the internal combustion engine to a rich combustion state with a rich air fuel ratio while the controller controls the selector valve to block the flow of the exhaust gas through the main exhaust passage, and then, afterwards, controls the selector valve to direct the flow of the exhaust gas through the main exhaust passage such that residual air remaining in the main exhaust passage mixes with rich exhaust gas from the bypass exhaust passage.

Abstract: An apparatus for an exhaust gas system includes a main exhaust passage, a main catalytic converter disposed in the main exhaust passage, a bypass exhaust passage, a bypass catalytic converter disposed in the bypass exhaust passage, and a valve configured to open or close a section of the main exhaust passage. The bypass exhaust passage bypasses the main exhaust passage between a branch point of the bypass exhaust passage out of the main exhaust passage and a junction with the main exhaust passage at a upstream side of the main catalytic converter. A first sensor indicates a first air-fuel ratio of exhaust gas in the bypass exhaust passage. A second sensor indicates a second air-fuel ratio of exhaust gas flowing into the main catalytic converter. A controller determines whether the valve in the closed configuration leaks exhaust gas based on the first and second air-fuel ratios of exhaust gas.

Abstract: An exhaust system of the internal combustion engine comprises upstream main paths for cylinders that are attached to a side of a cylinder head and extend towards a side of the engine, and are connected to the respective cylinders; a downstream main path in which the upstream main paths join so as to become one flow path; a main catalytic converter provided on the downstream main path; bypasses that are split from the upstream main paths or the downstream main path; a bypass catalytic converter that is provided on the bypass; and flow path switching valves that open and close the upstream main paths so that exhaust discharged from the cylinders flows into the bypass. The bypass catalytic converter is provided below the upstream main paths.