A valve assembly for a vehicle exhaust system includes at least one pipe enclosing an exhaust gas flow path, the pipe defining a central axis, and at least one flexible flap positioned within the exhaust gas flowpath. The at least one flexible flap has one fixed edge held fixed to the pipe and extends to a distal edge that is free to bend in response to an increase in exhaust gas flow pressure to provide a variable restriction to flow through the pipe that varies in response to a pressure difference upstream and downstream of the at least one flexible flap.

A valve assembly for a vehicle exhaust system includes a rigid mount structure that is configured to be mounted within an exhaust component that defines an exhaust gas passage. The valve assembly further includes a plurality of flexible members that each extend from a first end to a second end. One of the first ends and second ends of the flexible members is fixed to the rigid mount structure and the other of the first ends and second ends is free to move such that the plurality of flexible members creates a variable restriction to flow through the exhaust component that varies in response to a pressure difference upstream and downstream of the plurality of flexible members.

A vehicle comprising: an internal combustion engine having a cylinder and an exhaust manifold for collecting exhaust gases expelled from the cylinder; an exhaust system configured to channel exhaust gases along a flow path from the exhaust manifold to an exhaust outlet, the exhaust system comprising an exhaust component configured to cause an alteration to engine-generated sound pulses passing through the exhaust component; and a sound bypass device comprising a sound inlet port at a first location on the exhaust system before a first exhaust component along the flow path and a sound outlet port at a second location on the exhaust system after the first exhaust component along the flow path, the sound bypass device being configured to transmit engine-generated sound pulses from the sound inlet port to the sound outlet port whilst preventing flow of exhaust gases from the sound inlet port to the sound outlet port.

A vehicle comprising: an internal combustion engine having a cylinder and an exhaust manifold for collecting exhaust gases expelled from the cylinder; an exhaust system configured to channel exhaust gases along a flow path from the exhaust manifold to an exhaust outlet, the exhaust system comprising an exhaust component configured to cause an alteration to engine-generated sound pulses passing through the exhaust component; and a sound bypass device comprising a sound inlet port at a first location on the exhaust system before a first exhaust component along the flow path and a sound outlet port at a second location on the exhaust system after the first exhaust component along the flow path, the sound bypass device being configured to transmit engine-generated sound pulses from the sound inlet port to the sound outlet port whilst preventing flow of exhaust gases from the sound inlet port to the sound outlet port.

Road vehicle having: a passenger compartment; an internal combustion engine provided with at least one exhaust duct, which originates from an exhaust manifold and has at least one exhaust gas treatment device; and an exhaust noise transmission device provided with a transmission duct, which originates from the exhaust duct, and with a symposer device, which is arranged inside the transmission duct, is pneumatically insulating and is acoustically permeable; an inlet of the transmission duct being arranged between the exhaust manifold and the exhaust gas treatment device, hence upstream of the exhaust gas treatment device.

Intake sound reduction device for internal combustion engine includes an elastic member formed into substantially cylindrical shape and having an open base end, a top end sealed by an end surface wall and a bellows circumferential wall; a base plate retaining base end of elastic member; and a communication pipe whose one end is connected to base plate so that a volume chamber formed inside elastic member communicates with an intake passage of the engine. Intake sound reduction device has first resonance system formed by expansion and contraction in axial direction of elastic member and second resonance system formed by film-vibration of end surface wall. When either one of resonance frequencies of the first and second resonance systems is primary resonance frequency and the other is secondary resonance frequency, the primary resonance frequency is set to 30200 Hz and the secondary resonance frequency is set to 50300 Hz.

Intake sound reduction device for internal combustion engine includes an elastic member formed into substantially cylindrical shape and having an open base end, a top end sealed by an end surface wall and a bellows circumferential wall; a base plate retaining base end of elastic member; and a communication pipe whose one end is connected to base plate so that a volume chamber formed inside elastic member communicates with an intake passage of the engine. Intake sound reduction device has first resonance system formed by expansion and contraction in axial direction of elastic member and second resonance system formed by film-vibration of end surface wall. When either one of resonance frequencies of the first and second resonance systems is primary resonance frequency and the other is secondary resonance frequency, the primary resonance frequency is set to 30200 Hz and the secondary resonance frequency is set to 50300 Hz.