Abstract: A cylinder head with which exhaust manifolds are integrated includes a secondary air supply passage configured to include: a main passage disposed above combustion chambers of an engine, and extending along a cylinder line direction; and plural branch passages establishing individual communications between the main passage and corresponding exhaust ports. The respective plural branch passages are so disposed as to be inclined downward from the main passage toward the exhaust ports. Accordingly, it is possible to prevent corrosion of the cylinder head due to stagnation of condensed water.

Abstract: An exhaust system in an engine includes an exhaust passage including an outlet, in fluidic communication with at least one combustion chamber in the engine, and integrated into a cylinder head in the engine and a flow rotation element including at least one vane, the flow rotation element positioned in the outlet of the exhaust passage swirling exhaust airflow exiting the exhaust passage.

Abstract: Various methods and systems are provided for cooling exhaust system components. In one example, a method comprises directing compressed air onto an exterior of an engine exhaust passage valve.

Abstract: A reed valve is adapted to be fixed to a fixing member. The reed valve includes a valve plate and a resiliently deformable reed. The valve plate is fixed to the fixing member and includes a frame part and a supporting column. The frame part has an opening inward of the frame part. The opening passes through the frame part in a thickness direction of the valve plate. The supporting column is disposed across an inside of the opening. The reed is configured to open or close the opening. The frame part includes a frame seating surface with which the reed is engaged. The supporting column includes a column seating surface with which the reed is engaged. The column seating surface is recessed relative to the frame seating surface in the thickness direction.

Abstract: An exhaust manifold includes: an inlet portion which collects exhaust gas discharged through a first to a fourth exhaust ports; an outlet portion discharging the exhaust gas; and a tube portion connecting the inlet and the outlet portions. The inlet portion comprises: a first inlet portion one end of which communicates with the first and the second exhaust ports; and a second inlet portion one end of which communicates with the third and the fourth exhaust ports. Since the inlet portion is provided as two considering the combustion sequence, the productability and the economic feasibility can be enhanced, and the surrounding space can be enlarged to enhance the workability, and a simple exterior appearance can be obtained, and interference between exhaust gases can be effectively prevented, and since the size of the exhaust manifold can be increased, an engine load can be reduced to improve the fuel mileage.

Abstract: A secondary air system comprising a variable speed air pump and a gated check valve connected between the variable speed air pump and an IC engine. The gated check valve has two ports, and generally, a first of the two ports is connected to a first bank of engine cylinders, and a second of the two ports is connected to a second bank of engine cylinders. The system further comprises a controller for controlling the speed of the variable speed air pump, and the positioning of the gated check valve. The gated check valve is operable to fully close air flow to both ports, fully open air flow to one of the two ports, or variably split air flow between the two ports.

Abstract: A secondary air injection or SAIR system is illustrated and described which includes a first air injection path defined by in part by a lower ditch formed in the head mounting surface of the cylinder block, and a second air injection path defined in part by a second ditch formed in the block mounting surface. The cylinder head gasket is used to separate and seal the first ditch from the second ditch. The first and second air injection paths are separate and isolated from one another such that secondary air may be selectively introduced through the first air injection path into the first exhaust leg and selective introduced through the second injection path into the second exhaust leg independent of the first air injection path.

Abstract: A method for operating a spark-ignition engine having a three-way catalyst and a particulate filter downstream thereof, comprising: oscillating an exhaust air-fuel ratio entering the particulate filter to generate air-fuel ratio oscillations downstream of the particulate filter, while increasing exhaust temperature; when the downstream oscillations are sufficiently dissipated, enleaning the exhaust air-fuel ratio entering the particulate filter; and reducing the enleanment when an exhaust operating parameter is beyond a threshold amount.

Abstract: An exhaust collector system for discharging a flow of exhaust gases from an internal combustion engine. The exhaust collector system includes a plurality of primary headers having their discharge portions merged together at a merge angle into a substantially oval or obround-shaped manifold outlet, and a substantially-round secondary pipe having a pipe inlet with a diameter greater than the diameter of the primary headers. The exhaust collector system also includes an oval-to-round collector flowtube which has a substantially oval-or obround-shaped collector inlet that is coupled with the manifold outlet and a substantially-round collector outlet that is coupled with the pipe inlet. The collector flowtube has a constant circumference along its entire length and a transverse cross-sectional area that continuously increases from the collector inlet to the collector outlet to cause a continuous expansion of the flow of exhaust gases.

Abstract: An AI pipe (1) is formed with a first housing (11) and a second housing (21). The first housing (11) is made from a thin metal sheet and has a clamp portion (C1) that was left remaining. The second housing (21) is also made of a thin metal sheet and also has a clamp portion (C2) that was left remaining. When fitted together, the first housing (11) and the second housing (21) form a pipe portion (31). With this AI pipe (1), a through-hole (H) which is punched out by press working is formed in at least one of the clamping portion (C1) and the clamping portion (C2).

Abstract: A multi-cylinder internal combustion engine capable of decreasing the pressure or temperature of exhaust gas. The internal combustion engine includes at least two cylinders and an exhaust path. The exhaust path includes a convergent-divergent nozzle and an exhaust merging section provided upstream with respect to an upstream end of the divergent section arranged to connect only exhaust ports of combustion chambers for which the opening periods do not overlap. A shock wave propagating in a merging upstream section is branched at a connection section, and the branched shock wave is reflected by an exhaust valve of cylinder and collides against the exhaust gas. In accompaniment with the passage of the exhaust gas having the pressure increased by the shock wave through the convergent-divergent nozzle, a new shock wave propagating in a downstream direction in the exhaust path is generated and also an expansion wave propagating in an upstream direction in the exhaust path is generated.

Abstract: An engine includes a cylinder, an exhaust port, an exhaust valve, a secondary air supply pipe, and an electromagnetic valve. The electromagnetic valve is opened in a predetermined time period after a point in time when a lift amount of the exhaust valve reaches about half a maximum value during a time period in which an opening of the exhaust port is opened. This causes air to be supplied from a secondary air supply pipe to the exhaust port.

Abstract: An X-tube (1) is provided, for an at least partly double-flow exhaust system (2) of an internal combustion engine, especially of a motor vehicle, with a housing (3), which comprises two half shells (4, 5) and which has two inlet openings (7, 8) on an inlet side (6) and two outlet openings (10, 11) on an outlet side (9). The housing provides an interior space (12), which is enclosed by the housing (3) and to which the openings (7, 8, 10, 11) are connected in a communicating manner, with a bottom—partition (13), which is designed as a separate component in relation to the two half shells (4, 5) and which divides the interior space (12) into two ducts (14, 15), which are each connected to an inlet opening (7, 8) and to an outlet opening (10, 11) in a communicating manner. The bottom (13) is made permeable for airborne sound and connects the two ducts (14, 15) to one another in an airborne sound-transmitting manner.

Abstract: This invention is to provide a tappet clearance adjusting cover coupled with a secondary air valve. The tappet clearance adjusting cover is disposed on a cylinder head of an engine. The secondary air valve includes a recessed element and a cap which jointly form a receiving space receiving therein a one-way valve. The recessed element is provided with an inlet pipe interposed between the cap and the tappet clearance adjusting cover. By disposing the secondary air valve on the tappet clearance adjusting cover and arranging the inlet pipe between the cap and the tappet clearance adjusting cover, with the one-way valve received in the receiving space of the secondary air valve, heat dissipation can be improved while the one-way valve is protected against premature deterioration and carbon deposition caused by a high-temperature exhaust gas from the cylinder head. Thus, reliability as well as a service life of the one-way valve is effectively increased.

Abstract: An exhaust manifold includes a plurality of branch pipes that guide exhaust gas discharged from cylinders, and a junction pipe that converges downstream-side end portions of the plurality of branch pipes in a flow direction of exhaust gas, and that has a drawn portion that is formed by drawing so as to be constricted in a radial direction of the drawn portion. The junction pipe is provided with a sensor that detects the oxygen concentration in exhaust gas. The sensor is provided at a downstream side of a deepest draw inside diameter in the flow direction of exhaust gas. The deepest draw inside diameter is the smallest inside diameter of the drawn portion.

Abstract: A secondary-air supply system for an internal combustion engine, including a catalyst provided in an exhaust passage and configured to purify exhaust gas from the engine, and a secondary-air supply source and a secondary-air valve provided in a secondary-air passage connected upstream from the catalyst. A secondary-air supply device is configured to drive the secondary-air supply source and to open the secondary-air valve to supply secondary air to the exhaust passage upstream from the catalyst under a warm-up condition of the engine. Secondary-air supply control means is configured to control the secondary-air supply device to drive the secondary-air supply source and to open the secondary-air valve under a high-load operating condition where a flow rate of the exhaust gas is high, the high-load operating condition being different from the warm-up condition.

Abstract: An internal combustion engine includes an exhaust-gas system with n>1 exhaust-gas flow configurations, wherein n is an integer. The exhaust-gas flow configurations are at least partly separated from one another and each of the exhaust-gas flow configurations includes at least one catalytic converter. The internal combustion engine includes a secondary air supply system with at least one secondary air pump and at least one secondary air valve. The at least one secondary air pump is connected, via the at least one secondary air valve, to at most n?1 of the exhaust-gas flow configurations upstream of the at least one catalytic converter of the at most n?1 of the exhaust-gas flow configurations. The remaining ones of the exhaust-gas flow configurations are separated from the secondary air supply system.

Abstract: A secondary air supply system includes a CPU, a first air supply pipe, a second air supply pipe, a first shut-off valve, and a second shut-off valve. First ends of the first air supply pipe and the second air supply pipe are connected to an air cleaner box and the other ends thereof are connected to an exhaust port. The CPU controls opening/closing of the first shut-off valve and the second shut-off valve based on a state of an engine. The first shut-off valve and the second shut-off valve are selectively opened by the CPU, so that air in the air cleaner box is supplied to the exhaust port through the first air supply pipe and/or the second air supply pipe.

Abstract: A secondary air supply system includes a CPU, a ROM, an air supply pipe, and an air amount adjusting valve. One end of the air supply pipe is connected to an air cleaner box and the other end is connected to an exhaust port. Secondary air in the air cleaner box is supplied to the exhaust port through the air supply pipe. An amount of the secondary air to be supplied from the air supply pipe to the exhaust port is adjusted by the air amount adjusting valve. A target air-fuel ratio depending on a state of the engine is stored in the ROM. The CPU controls the air amount adjusting valve based on the state of the engine so that an air-fuel ratio in the exhaust port is the target air-fuel ratio.

Abstract: An exhaust manifold may include a manifold body and a flange. The manifold body may include a first tube that forms an exhaust gas inlet. The flange may be coupled to the manifold body and may fix the manifold body to an engine. The flange may include a first aperture having first and second portions located along an axial extent of the first aperture. The first portion may extend to a first end surface of the flange and the second portion may extend to a second end surface of the flange. The first portion may have a first radial width that is less than a second radial width of the second portion. The second portion may receive an end of the first tube therein. The first tube may be fixed to the flange at a location within the first aperture between the first portion and the second end surface.

Abstract: A system and method for treating exhaust gasses from an engine is described. In one example, the exhaust gasses are routed from the engine to atmosphere through a helical exhaust passage. The helical exhaust passage includes a plurality of spatially separated exhaust passages that separates the exhaust flow into separated smaller flows, wherein the smaller flows are re-introduced into a common passage and re-combined to form a single exhaust flow, and wherein the plurality of spatially separated exhaust passages induces a helical flow pattern within the re-combined exhaust flow.

Abstract: An exhaust filter system includes a particulate filter (PF) that is disposed downstream from an engine. The PF filters particulates within an exhaust from the engine. A heating element heats particulate matter in the PF. A fastener limits expansion movement of the heating element relative to the PF.

Abstract: The present invention provides an engine including a secondary air supply apparatus for supplying a secondary air to an exhaust gas passage in a cylinder head. The engine comprises a secondary air passage of the secondary air supply apparatus which extends from an outer peripheral surface of the cylinder head through an under-portion of the exhaust gas passage into the exhaust gas passage. The secondary air passage has a groove geometry of passage portion on a matching surface between the cylinder head and a cylinder body.

Abstract: When a fuel as a reducing agent is supplied to a NOx catalyst on which a NOx or a SOx is reduced, a flow rate of exhaust gas that flows through an exhaust passage is changed, and the fuel is supplied to the exhaust gas flowing through the exhaust passage at a plurality of timings (?T1, ?T2) when the exhaust gas flows at different flow rates.

Abstract: An exhaust system includes a particulate filter (PF) that is disposed downstream from an engine. The PF filters particulates within an exhaust from the engine. A heating element heats particulate matter in the PF. A catalyst substrate or a flow converter is disposed upstream from said heating element. The catalyst substrate oxidizes the exhaust prior to reception by the heating element. The flow converter converts turbulent exhaust flow to laminar exhaust flow prior to reception by the heating element.

Abstract: In an exhaust purification system that purifies exhaust from a plurality of cylinder groups of an internal combustion engine, an exhaust passageway (1,51) from each cylinder group is divided into a plurality of passageways (2a, 2b, 52a, 52b/3,53). With regard to one or more of the divided exhaust passageways (3,53), the amount of exhaust passing therethrough is reduced so as to reduce the heat release to the outside from the exhaust as a whole. In this manner, the temperature of exhaust introduced into an exhaust purification device (4,54) is kept at high temperature.

Abstract: In a V-type engine, throttle devices are disposed between front and rear cylinders disposed in a V-shape, and an air cleaner is disposed above the throttle device. A secondary air pipe is connected to a secondary air entrance portion formed in an outer peripheral wall surface of each of the cylinders. A secondary air on-off valve is disposed below the throttle device, and the secondary air on-off valve is provided so as to be substantially accommodated in a V-bank space between the cylinders. A secondary air inlet of the secondary air on-off valve is connected to the air cleaner by the secondary air source pipe extended upward, a secondary air pipe for each cylinder is connected to the secondary air outlet for each cylinder, and the secondary air outlet for each cylinder is formed in the secondary air on-off valve.

Abstract: An ECU executes a program including a step (S102) of limiting the maximum opening amount of a throttle valve to TH (1) when failure has occurred in a pressure sensor (“YES” in step S100); a step (S202) of limiting the maximum opening amount to TH (2) when open failure has occurred in at least one of two vacuum pressure ASVs provided for banks of a V-type engine, and an electromagnetic ASV (“YES” in step S200); a step (S302) of limiting the maximum opening amount to TH (3) when open failure has occurred in both of the vacuum pressure ASVs (“YES” in step S300); a step (S402) of limiting the maximum opening amount to TH (4) when open failure has occurred in one of the vacuum pressure ASVs (“YES” in step S400); and a step (S502) of reducing the throttle valve opening amount TH to the limited maximum opening amount.

Abstract: Disclosed is an exhaust system for discharging combusted gases from the cylinder of a vehicle engine, which comprises an exhaust manifold with a plurality of exhaust gas runners, wherein the exhaust gas runners are spaced so as to avoid an exhaust gas interference.

Abstract: An exhaust system for an internal combustion engine includes a catalytic device within an exhaust path of the engine, wherein the catalytic device includes a housing with a catalyst carrier. A length of the catalyst carrier along a longitudinal axis, measured along a downstream flow direction of exhaust gas within the exhaust path, is substantially the same or a shorter than the upstream distance traveled by a reverse flow of exhaust gas during an exhaust gas pulsation within the housing. With this type of configuration, due to reciprocating movements of the exhaust gas caused by the pulsations, the same exhaust gas passes through the catalyst carrier multiple times. Thus, an increased number of heat exchanges take place within the catalyst carrier, which rapidly increases the catalyst temperature after a cold engine start.

Abstract: The present invention relates to a mixing element and an exhaust system of an internal combustion engine. The mixing element has two inlet openings and two outlet openings, wherein each inlet opening communicates with both outlet openings.

Abstract: In an exhaust manifold of a four-cylinder engine four cylinders of which line up in order of cylinder #1, cylinder #2, cylinder #3 and cylinder #4, temperature rise performance of a manifold catalyst improves by shortening a total length of the exhaust manifold while preventing exhaust gas interference between the cylinders. Therefore, an exhaust manifold branch of cylinder #1 and an exhaust manifold branch of cylinder #4 in outward sides of the engine that are not fired in succession are made convergent with its convergence angle ?1 being equal to or below 20 degrees to form a first convergent exhaust manifold branch and an exhaust manifold branch of cylinder #2 and an exhaust manifold branch of cylinder # 3 between the cylinder #1 and cylinder #4 that are not fired in succession are made convergent at a minimum distance having a laterally projected shape to form a second convergent exhaust manifold branch.

Abstract: In an exhaust system, a first oxygen sensor is attached to an exhaust pipe connected to a standard cylinder in which the amount of injected fuel is the closest to the average of the amounts of fuel injected in a plurality of cylinders. A controller calculates the air-fuel ratio of the standard cylinder based on the value detected by the first oxygen sensor. Then, based on the difference between the calculated air-fuel ratio of the standard cylinder and a predetermined target air-fuel ratio, the amount of correction to the amount of fuel injected in the standard cylinder is determined such that the air-fuel ratio of the standard cylinder is equal to the target air-fuel ratio. Furthermore, based on the amount of correction to the amount of fuel injected in the standard cylinder, the amounts of correction of the other cylinders are determined.

Abstract: In a V-type engine, throttle devices are disposed between front and rear cylinders disposed in a V-shape, and an air cleaner is disposed above the throttle device. A secondary air pipe is connected to a secondary air entrance portion formed in an outer peripheral wall surface of each of the cylinders. A secondary air on-off valve is disposed below the throttle device, and the secondary air on-off valve is provided so as to be substantially accommodated in a V-bank space between the cylinders. A secondary air inlet of the secondary air on-off valve is connected to the air cleaner by the secondary air source pipe extended upward, a secondary air pipe for each cylinder is connected to the secondary air outlet for each cylinder, and the secondary air outlet for each cylinder is formed in the secondary air on-off valve.

Abstract: An exhaust manifold includes an open/close valve that switches between either closing or opening the exhaust path of a collection section, and switches the exhaust path of the exhaust gas between passing through or not passing through a bypass path containing an upstream catalyst. There is a partition wall structure in a pipe-mounting member so that when the valve is closed such that the exhaust gas during cold start is led to the upstream catalyst, the exhaust paths for each of the branch pipes on the upstream side of the valve inside a collection section are independent from one another. When the valve is closed, the downstream side of each of the branch pipes is not continuous inside the collection section, so the flow of air is prevented in this section, and exhaust interference and loss of exhaust heat are reduced.

Abstract: A supercharging system for an internal combustion engine includes an exhaust introduction passage for introducing exhaust gas from an internal combustion engine; an exhaust discharge passage for introducing the exhaust gas from the exhaust introduction passage and exhausting the exhaust gas to an exterior; a mixture part arranged between the exhaust introduction passage and the exhaust discharge passage, for changing internal pressure into negative pressure upon accelerating flowing velocity of the exhaust gas with a narrowed flowing passage set to have a smaller diameter than the exhaust introduction pipe; an absorption passage for mixing outside air and the exhaust gas inside the mixture part upon introducing the outside air with use of negative pressure into an inside of the mixture part; and an intake passage for taking out and returning a part of mixed gas mixed inside the mixture part to a side of the internal combustion engine.

Abstract: A 4-cycle engine for a motorcycle has a secondary-air supplier for supplying secondary air to exhaust ducts. The engine includes a recess, which is depressed toward the engine, on a cylinder-head cover for holding a control valve of the secondary-air supplier. The recess and the control valve are positioned between two innermost cylinders of the array of the cylinders. Check valves, which are connected to downstream regions of the control valve, are each disposed between two outermost cylinders of the array of the cylinders.

Abstract: In a secondary air supplying structure of an internal combustion engine, extending portions protruding upward are arranged in the number corresponding to the number of cylinders. Extending portions are each provided with a secondary air distribution path. To a surface of extending portion to which secondary air supplying pipe abuts, a seating face that conforms to the outer shape of secondary air supplying pipe is formed. Secondary air distributing path is arranged to be inclined downwardly from secondary air supplying pipe side toward the cylinder exhaust system of cylinder head. Thus, it is possible to provide the secondary air supplying structure of an internal combustion engine that can attain an improvement in the strength of the secondary air supplying path, reduction of the space, rust prevention, reduced costs, reduced weight, simplified structure, and prevention of thermal damage to other components.

Abstract: In a secondary air supply system, each of two branch portions of a secondary air supply pipe that is divided from a joint portion is provided with an air control valve, and the joint portion is provided with a pressure sensor and an auxiliary air control valve. The air control valves are opened at different timings such that pressure fluctuations in the joint portion upon opening of the firstly and the secondly opened air control valves are measured. An abnormality diagnosis is performed with respect to those two air control valves based on combinations of the aforementioned two pressure fluctuations.

Abstract: An exhaust system for a dual crankshaft engine system having a first engine and a second engine having a common exhaust member open at an end thereof for venting engine exhaust. A first exhaust member is adapted to be coupled to the first engine and coupled to the common exhaust member. The first exhaust member has a first catalytic converter formed thereon. A second exhaust member is adapted to be coupled to the first engine and coupled to the common exhaust member and has a second catalytic converter formed thereon. A third exhaust member is adapted to be coupled to the second engine and coupled to the common exhaust member. A fourth exhaust member is adapted to be coupled to the second exhaust engine and coupled to the common exhaust member. A third catalytic converter is provided in the exhaust member.

Abstract: A waste heat recovering device for an internal combustion engine includes: an internal combustion engine; and an evaporator into which an exhaust gas of the internal combustion engine is introduced as a high temperature fluid. An exhaust gas inlet of the evaporator is placed adjacent to an exhaust valve of the internal combustion engine. Thus, there can be provided a waste heat recovering device having a high waste heat recovery rate.

Abstract: A induction exhaust system, for an internal combustion engine, capable of the multi step processes of 1) scavenging the chamber of exhaust gases and free radicals, 2) breaking the scavenge vacuum wave behind each energetic exhaust pulse, releasing said free radicals and the overscavenged air fuel vacuumed from the intake manifold during valve overlap, and 3) induction of such free radicals, unburned fuel, and fresh matter including atmospheric air.

Abstract: In an exhaust manifold of a four-cylinder engine four cylinders of which line up in order of cylinder #1, cylinder #2, cylinder #3 and cylinder #4, temperature rise performance of a manifold catalyst improves by shortening a total length of the exhaust manifold while preventing exhaust gas interference between the cylinders. Therefore, an exhaust manifold branch of cylinder #1 and an exhaust manifold branch of cylinder #4 in outward sides of the engine that are not fired in succession are made convergent with its convergence angle ?1 being equal to or below 20 degrees to form a first convergent exhaust manifold branch and an exhaust manifold branch of cylinder #2 and an exhaust manifold branch of cylinder #3 between the cylinder #1 and cylinder #4 that are not fired in succession are made convergent at a minimum distance having a laterally projected shape to form a second convergent exhaust manifold branch.

Abstract: An exhaust muffler system for use on a motorcycle or four-wheeled vehicle provides for operation in either of two modes, a regular configuration that provides a high degree of noise reduction, or a racing specification that provides for a freer-flowing exhaust. Without changing the main body of the muffler, an operator can choose between a quieter, public road setting or a louder, high performance setting. The muffler is provided with two interchangeable spark arresters, and a main body having multiple expansion chambers therein, defined by bulkheads. When a regular spark arrester is installed, exhaust gas passes through one bulkhead three times, greatly reducing the noise produced. With the spark arrester removed, the exhaust gas passes straight through to the open air, enhancing performance. A seal is provided between the bulkheads and the spark arrester, which provides for extension or retraction in the lengthwise direction of the tail pipe.

Abstract: A first heat-resistant filter medium is disposed in an exhaust pathway of an internal combustion engine. The first heat-resistant filter medium traps hydrocarbon compounds and carbon-containing particulates included in a flow of exhaust gas in a dispersive manner to bring the respective particulates and hydrocarbon compounds in contact with oxygen included in the exhaust gas. The trapped hydrocarbon compounds and the trapped carbon-containing particulates are subjected to combustion with the exhaust gas having a filter inflow temperature lower than a combustible temperature of the carbon-containing particulates. A second heat-resistant filter medium is further disposed downstream of the first heat-resistant filter medium to trap the remaining carbon-containing particulates, which have not been trapped by the first heat-resistant filter medium but have passed through the first heat-resistant filter medium. This arrangement desirably enhances the reduction rate of the particulates.

Abstract: A method and an apparatus for determining the performance of a secondary air charging system for an internal combustion engine in order to determine the amount of secondary air supplied in the secondary air charging system. This is achieved by measuring the heat generated by the compression of the secondary air with temperature sensors. Insofar as the secondary air charging system is powered by a turbine arranged in parallel with the throttle valve in the intake tract, the measured temperature value for the compressor can be compared with a reduction in temperature of the intake air behind the turbine. Reliable information concerning the amount of secondary air supplied can be determined by simple sensors, thereby obviating the need for an air-mass sensor which is expensive to produce and sensitive to contamination.

Abstract: The intake and exhaust control systems are operable in varying modes, according to the engine speed, by a single actuator. The intake control system includes an intake valve that allows a variable amount of air into an air cleaner depending on vehicle speed. The exhaust control system includes an exhaust control valve, and a primary and a secondary exhaust purifying system located downstream of the exhaust control valve. The flow into the exhaust purifying systems may also be controlled according to engine speed.

Abstract: A 4-cycle engine for a motorcycle has a secondary-air supplier for supplying secondary air to exhaust ducts. The engine includes a recess, which is depressed toward the engine, on a cylinder-head cover for holding a control valve of the secondary-air supplier. The recess and the control valve are positioned between two innermost cylinders of the array of the cylinders. Check valves, which are connected to downstream regions of the control valve, are each disposed between two outermost cylinders of the array of the cylinders.

Abstract: An exhaust manifold for vehicle is disclosed. First and fourth runners among a plurality of runners connected to cylinders of an engine are respectively connected to sides of a gas confluence part. Second and third runners disposed between the first and fourth runners are joined together integrally before being connected to the gas confluence part.

Abstract: An internal combustion engine includes an air pump that supplies secondary air to an upstream side of an exhaust gas control catalyst in an exhaust pipe via a secondary air supply passage; an adjusting device that adjusts an intake air amount delivered into a combustion chamber from an intake pipe; and a controller that performs control for increase correction of the intake air amount adjusted by the adjusting device when the air pump performs an operation of supplying the secondary air. Thus, it is possible to prevent a problem caused by a reduction in an engine speed due to the secondary air supply.