Abstract: The invention concerns an exhaust silencer arrangement with a transverse exhaust silencer in a four-chamber type of construction, in particular for very small passenger-transporting motor vehicles, with a 3-cylinder rear-mounted engine and an exhaust gas turbocharger. The silencer comprises a housing which is composed of two half shells and accommodates a catalyst module in an integrated manner. The catalyst module, which does not have its own housing, forms a silencer system partition which divides the silencer into a 3-pot main chamber and an additional chamber which is in particular a resonator chamber and communicates with the main chamber via connection ducts formed in the half-shell housing.

Abstract: A flexible tube for an automobile exhaust system which has a bellow assembly to absorb the first exhaust pipe and the second exhaust pipe for the an exhaust system having a cylindrical outer cover (5) made of plate to cover the outer periphery of the bellows (3)1 the first collar (7') and the second collar (7") with the risers (7a', 7a") bent toward the inner surface (5a) of the outer cover (5); the first elongation displacement stopper member (6') and the second elongation member displacement stopper member (6") respectively formed by bending the inner side of the outer cover (5); and the first elastic stopper member (8') and the second elastic stopper member (8") provided at the risers (7a', 7a") of both collars (7', 7"). As a further modification, the second outer cover (9) may be provided inside of the outer cover (5) to form displacement stoppers (9a, 9b) by bending the both end portions of the second outer cover.

Abstract: In an engine exhaust system, an NOx catalyst for occluding NOx in a state of the lean air-fuel ratio and reducing the occluded NOx in the state of the rich air-fuel ratio. A CPU sets a target air-fuel ratio of a mixture supplied to an engine to the lean side with respect to the stoichiometric air-fuel ratio for the lean mixture combustion. The CPU sets a rich time for a rich mixture combustion in accordance with the engine operating state and the NOx purification rate in the NOx catalyst. In this moment, the shortest rich time is set within a range in which a desired NOx purification rate by the NOx catalyst is obtained. A three-way catalyst may be arranged upstream of the NOx catalyst. The three-way catalyst carries only a noble metal such as platinum having no oxygen storing capability.

Abstract: A deterioration diagnosing system for a NOx-occluded catalyst comprises an inlet NOx concentration estimating unit which estimates NOx concentration at an inlet part of the catalyst; an outlet NOx concentration detecting unit which detects NOx concentration at an outlet part of the catalyst; and a deterioration degree judging unit which judges a deterioration degree of the catalyst in accordance with a rate of the minimum value of NOx concentration detected by the detecting unit for a predetermined period to a value of NOx concentration estimated by the estimating unit at the time when the minimum value of NOx concentration is detected. The predetermined period is a period between a time when the engine exhaust gas shows the stoichiometric and/or richer air/fuel ratio and a subsequent time when the engine exhaust gas shows the stoichiometric and/or richer air/fuel ratio.

Abstract: An exhaust manifold has inner and outer tubes made of stainless steel and welded to flanges provided at inlet ports of the exhaust manifold, from which exhaust gas discharged from an engine enters the exhaust manifold. The inner tube has flat portions, and shield plates disposed within the inner tube protect the flat portions from being directly vibrated by pressure waves of the exhaust gas. Accordingly, the vibration of the flat portions is lowered, so that high frequency noise from the exhaust manifold is reduced.