A variable intake system may include an air duct that guides intake air into an engine and a variable valve having a variable opening degree, to adjust an amount of the intake air, wherein the air duct includes a first inlet and a second inlet that may be opened to an outside, wherein the air duct has a first flow path having one end connected with the first inlet and a second flow path having one end connected with the second inlet, wherein the second flow path shares a part of the first flow path, wherein another end of the first flow path and another end of the second flow path share a same outlet, and wherein a length of the second flow path may be longer than a length of the first flow path.

A bypass mechanism is disclosed for use with a turbocharger. The bypass mechanism may have an exhaust passage formed by at least a first wall, and a bypass manifold formed by at least a second wall surrounding the exhaust passage and including a space between the first wall and the second wall. The bypass mechanism may further have at least one opening in the first wall fluidly connecting the exhaust passage with the space. At least one valve is configured to open and close the opening to selectively allow exhaust gas to pass from the exhaust passage to the space through the at least one opening. The space may be fluidly connected to at least one entry passage of an exhaust stack. In addition, the at least one opening and the at least one entry passage may be positioned on opposite sides of the exhaust passage.

The present air intake control valve includes a valve body and a seal portion being elastically deformable to seal between an inner wall surface of an air intake port and the valve body. The seal portion is formed in a bending configuration including a first hinge portion and a second hinge portion each serving as a supporting point upon elastic deformation of the seal portion. One of the first hinge portion and the second hinge portion is arranged at an upstream side of the air intake port and the other of the first hinge portion and the second hinge portion is arranged at a downstream side in a state where the valve body is at a closed position.

The intake system has a valve seat, a plate valve, and an elastic sealing member. A path is provided to pass through the valve seat and to communicate with an intake passage of an internal combustion engine. The plate valve fits to or separates from the valve seat to close or open the path. The plate valve is provided with through holes passing through the plate valve in the thickness direction at a valve periphery part. The through holes are arranged linearly one after another in a peripheral direction of the plate valve to be offset to each other in the direction perpendicular to the peripheral direction. The elastic sealing member includes an elastic covering part that covers a first surface and a second surface of the plate valve and elastic coupling parts that are disposed in the through holes and are coupled with the elastic covering part at the first surface and the second surface.

An air intake device includes: an air intake port; and a valve that includes an elastically deformable seal portion disposed in a side end portion, and switches between flow paths of the air intake port by being turned around a turning shaft, wherein the side end portion of the valve is provided with a curved side end portion that extends from one end portion side to the other end portion side along an extension direction of the turning shaft while being curved.

An intake device includes: a plurality of intake ports which are adjacent to each other with a partition wall interposed therebetween; a valve body provided for each of the plurality of intake ports; a rotating shaft which rotates along with the valve body; and a bearing member which is disposed between the intake ports adjacent to each other and rotatably supports the rotating shaft of the valve body, wherein the bearing member includes a bearing main body having a bearing hole which rotatably supports the rotating shaft, and an arm portion which extends in a length larger than an inner diameter of the bearing hole from the bearing main body along the partition wall between the intake ports adjacent to each other and configures a bearing-side welding portion.

A silencer for noise reduction at an internal combustion engine is disclosed. The silencer comprises an input opening, an output opening, at least one chamber, and at least one partition configured to be inserted into and removed from the at least one chamber to convert the silencer to a collector.

An apparatus for adjusting power and noise characteristics of an internal combustion engine comprises a wall configured to define an engine cylinder that includes a bore and a compression relief passage. A compression relief valve is configured to selectively adjust fluid flow capacity of the compression relief passage. A manifold is configured to be in fluid communication with the exhaust passage and includes an exhaust bypass valve to permit exhaust to at least partially bypass a noise suppressor. Operational characteristics of the engine can be adjusted along a range that extends from a first set of operational characteristics present when both the compression relief valve and the exhaust bypass valve are in a fully open position to a second set of operational characteristics present when both the compression relief valve and the exhaust bypass valve are in a fully closed position.