An exhaust pipe structure having a variable confluence portion may include a first pipe to discharge exhaust gas generated by engine cylinders disposed in a first line, a second pipe to discharge exhaust gas generated by engine cylinders disposed in a second line, a confluence pipe provided with a first end connected to the first pipe for communication with the first pipe and a second end connected to the second pipe for communication with the second pipe, and a valve plate disposed in the confluence pipe and selectively opened and closed, in which the confluence pipe may include a main connection tube disposed at the first end of the confluence pipe and an entry confluence tube and a sub-entry confluence tube branched off from a middle of the confluence pipe and disposed at the second end of the confluence pipe.

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.

Provided is a muffler valve 1 that opens and closes an exhaust passage according to a pressure of an exhaust gas of an engine. A valve body 3 is swingably supported by a support shaft 4 with respect to a valve seat 2 having an opening 22, the valve body 3 is urged in a closing direction by a coil spring 5 externally inserted on the support shaft 4, a valve seat hook portion 23 is provided so as to embrace both ends of the support shaft 4 in a circumferential direction and is fixed to the support shaft 4, and a valve body winding portion 34 is provided so as to embrace the coil spring 5 in the circumferential direction from a direction opposite to the valve seat hook portion 23 and embrace the coil spring 5 over an entire length of the coil spring 5 in the circumferential direction. It is possible to prevent or suppress axial misalignment of the coil spring coaxially externally inserted on the support shaft for opening and closing the valve body as much as possible, and appropriately control the opening and closing of the valve body with high stability.

Methods and systems are provided for adjusting a position of an exhaust valve that regulates engine exhaust noise. In one example, the position of the exhaust valve is adjusted according to a distance between a first vehicle and a second vehicle. The exhaust valve may be adjusted to reduce an exhaust noise level when the distance between the first vehicle and the second vehicle is less than a threshold distance.

A road vehicle comprising: a passenger compartment; an internal combustion engine; an exhaust system, which releases into the atmosphere the gases generated by the combustion, is connected to the internal combustion engine, and ends with at least one silencer having at least one outlet pipe; and an exhaust noise transmission device, which is provided with a transmission conduit, which originates close to the outlet pipe of the silencer, ends in the area of a wall of the passenger compartment, and is provided, on the inside, with at least one insulating element, which is arranged inside the transmission conduit so as to tightly seal the transmission conduit.

The adjustable exhaust backpressure device allows for post-installation adjustment of additional backpressure. This allows a user to adjust how much backpressure is generated by testing, adjusting, and then re-testing. The adjustment can generally be performed without removing the device from the exhaust, and without replacing any parts. The adjustable exhaust backpressure device can be placed in any location following the engine. The adjustable exhaust backpressure device includes a body with an exhaust inlet and an exhaust outlet.

A slip-type active noise control muffler reducing exhaust noise of a vehicle may include at least two guides connected to an inner wall of a housing accommodating exhaust gas in the muffler and formed in a pipe shape in a longitudinal direction of the muffler, and a baffle positioned in a plane shape partitioning the interior of the housing and including an electromagnet on the plane shape to control an interval of the baffles through a movement signal by current applied to the electromagnet according to frequency calculated from the exhaust gas, in which the interval of the baffles may be controlled and the exhaust noise may be reduced by controlling the number of wavelengths depending on the frequency.

Methods and systems are provided for adjusting a position of an exhaust valve that regulates engine exhaust noise. In one example, the position of the exhaust valve is adjusted according to a road grade estimate. The road grade estimate may be based on a vehicle's present position on a road or a position that is a distance away from the vehicle's present position.

An exhaust-gas aftertreatment device (10) for an internal combustion engine, particularly for a marine diesel internal combustion engine operated using heavy fuel oil, includes a housing (11); an exhaust-gas chamber (12) defined by the housing (11), for permitting exhaust gas to flow continuously through the housing (11), an inlet (13) for permitting exhaust gas to flow into the housing and an outlet (14) for permitting exhaust gas to flow out of the housing (11); a sound damping chamber (15), defined by the housing (11) and coupled with the exhaust-gas chamber (12). The sound dampening chamber (15) is constructed to receive a fluid or a pourable solid at a fill level depending on the frequency of an exhaust sound to be damped.

An aerial vehicle that can comprise a housing comprising an outer wall at least partially defining an interior space, a mechanical power source at least partially located in the interior space of the housing, an exhaust header in communication with the mechanical power source for communicating exhaust fluid from the mechanical power source, and an exhaust system comprising at least an exhaust chamber extending at least partially in the interior space of the housing. The exhaust chamber can be in communication with the exhaust header, and the exhaust system can comprise an exhaust outlet for communicating the exhaust fluid from the exhaust system outside the aerial vehicle.