In one aspect, a system is provided and includes an engine including an exhaust valve, an exhaust manifold downstream of the exhaust valve and a muffler downstream of the exhaust manifold. The system also includes a catalyst positioned downstream of the exhaust valve.

A vehicle exhaust system includes an inner pipe in which exhaust gas from an internal combustion engine flows, and an outer pipe surrounding a part of the inner pipe. One end of the outer pipe is formed to have a diameter smaller than that of other portions of the outer pipe, and fixed to an outer surface of the inner pipe. A region of the outer pipe from the other end before the one end is a free region unattached to the outer surface of the inner pipe.

A tubular member for an exhaust gas treatment device according to at least one embodiment of the present invention includes: a tubular main body made of a metal; and an insulating layer formed at least on an inner peripheral surface of the tubular main body. The insulating layer contains glass containing a crystalline substance, and the insulating layer has a porosity of from 1% to 12%.

A tubular member for an exhaust gas treatment device according to at least one embodiment of the present invention includes: a tubular main body made of a metal; and an insulating layer formed at least on an inner peripheral surface of the tubular main body. The insulating layer contains glass, and the glass has a content of an alkali metal element of 1,000 ppm or less.

A mixer apparatus for an exhaust gas aftertreatment system of a motor vehicle. The apparatus includes a housing having enveloping, first end, and second end walls. An injection opening for an exhaust gas aftertreatment agent is in the enveloping wall. An inlet opening is in the first end wall. The injection opening is configured for mounting a metering module. A rectilinear metering axis, which extends through the metering module and corresponds to an injection direction of exhaust gas aftertreatment agent injected into the housing, tangentially contacts, at a contact point, a theoretical cylinder, disposed in the housing, having a variable radius and a cylinder axis that is congruent with a central axis of the housing. A region of the metering axis extending from the injection opening to the contact point is located, with respect to inflowing exhaust gas, in the shelter of an opening-free region of the first end wall.

Apparatuses and methods for tuning a muffler. An apparatus comprises a housing for a muffler, a first inlet pipe, and a second inlet pipe. The housing includes a coupling chamber. The first inlet pipe has a first set of physical features and carries exhaust to the coupling chamber. The second inlet pipe has a second set of physical features and carries the exhaust to the coupling chamber. The first set of physical features varies from the second set of physical features with respect to at least one physical feature such that a first sound waveform passing through the first inlet pipe and a second sound waveform passing through the second inlet pipe are uniquely tuned to thereby tune an overall sound waveform emitted by the muffler.

A tubular member for an exhaust gas treatment device according to at least one embodiment of the present invention includes: a tubular main body made of a metal; and an insulating layer formed at least on an inner peripheral surface of the tubular main body. The insulating layer contains glass containing a crystalline substance, and the insulating layer has a porosity of from 1% to 12%.

A tubular member for an exhaust gas treatment device according to at least one embodiment of the present invention includes: a tubular main body made of a metal; and an insulating layer formed at least on an inner peripheral surface of the tubular main body. The insulating layer contains glass, and the glass has a content of an alkali metal element of 1,000 ppm or less.

A tubular member for an exhaust gas treatment device according to at least one embodiment of the present invention includes: a tubular main body made of a metal; and an insulating layer formed at least on an inner peripheral surface of the tubular main body. The insulating layer contains glass, the glass contains barium, and the glass has a content of barium of 5 mol % or more.

The vehicle of the present application includes a vehicle frame; a muffler supported by the vehicle frame; and a supporting unit comprising a rubber damper, located between the muffler and the vehicle frame and, connected to the vehicle frame such that the muffler is suspended from the vehicle frame and supported by the vehicle frame. The supporting unit comprises a first bracket and a second bracket on the first bracket.