Abstract: A guiding portion of an intake valve head includes a specific tangent line, which, when the intake valve is in a fully open state, intersects with at least one selected from an ignition plug and a closed exhaust valve. A line segment that agrees with a tangent line contacting the guiding portion and extends from a contact point of the tangent line with the guiding portion to an intersection point of the tangent line with a central axis of the head is defined as a first line segment, a line segment that agrees with the central axis and extends from the intersection point toward the intake passage is defined as a second line segment, and an angle formed by the first second line segments is defined as a specific angle. The tangent line that minimizes the specific angle is the specific tangent line.

Abstract: Animal drinkers of an activation unit provided with two arms engaging respective valve pin in an axially oriented manner when pivoting an activator. This reduces wear and leads to a longer service life of the drinker valve. The respective arm can moreover have a channel through which the water exits the drinker valve and can be fed in a targeted manner to the activator to ensure that all of the water exiting the drinker valve makes its way into the water collection tray.

Abstract: An engine with a vertically oriented parallel valve and stem arrangement accommodating tumble flow to support spark-ignited fuel usage. The engine may be provided in a configuration generally suited for swirl flow, compression combustion fuel usage. However, the introduction of a unique, replaceable valve head assembly may be utilized to induce tumble flow within a combustion chamber of the engine. Thus, spark-ignited fuel may be utilized without requiring vast overhaul of the engine to accommodate such fuels. Notably, with the addition of such an assembly, diesel fuel may be replaced with natural gas on large scale equipment without the requirement of impractically burdensome or expensive measures.

Abstract: Throttle-at-valve apparatus, internal combustion engines employing throttle-at-valve apparatus, and methods of throttling an internal combustion engine using a throttle-at-valve apparatus, where the throttle-at-valve apparatus includes a throttle slide body disposed within a throttle slide cavity that is defined between and in fluid communication with both an unobstructed air intake passage and an intake valve of an internal combustion engine, where the air flow from the air intake passage to the intake valve is regulated by the reciprocal movement of the throttle slide body within the throttle slide cavity.

Abstract: A port injection engine, in which injected fuel readily vaporizes inside suction ports, includes: a suction port; a suction valve; and a port injector that injects fuel to an inner peripheral surface of the suction port. When the fuel is burned in a predetermined combustion cycle, an injection start of a fuel injection period is set within an end part of a valve opening period before the suction valve is fully closed, during a combustion cycle previous to the predetermined combustion cycle. The end part of the valve opening period is preferably set from 50° to 20° before the suction valve is fully closed at a crank angle.

Abstract: A cylinder head includes an exhaust port through which exhaust gas discharged out of a combustion chamber of an internal combustion engine passes. The cylinder head includes a first fin and a second fin projecting from an inner wall of the exhaust port and extending in a flow direction of the exhaust gas. The cylinder head includes a first projection projecting from the inner wall of the exhaust port and extending in a direction intersecting the first fin. The cylinder head also includes a second projection projecting from the inner wall of the exhaust port and extending in a direction intersecting the second fin.

Abstract: This control apparatus of an engine includes an engine, a state quantity setting device, an injector, a spark plug, and a controller. The controller outputs a control signal to the spark plug at a predetermined ignition timing such that, after air-fuel mixture is ignited and combustion is started, unburned air-fuel mixture is combusted by autoignition, and the controller advances an ignition timing when the temperature before start of compression in a combustion chamber is to be reduced.

Abstract: A control system for a pre-mixture compression-ignition engine is provided, configured such that in a first combustion mode, the control unit controls the fuel injection valve to have a fuel amount within a mixture gas in an outer circumferential portion of the combustion chamber larger than in the center portion, the swirl generating part to generate a swirl flow in the outer circumferential portion, and the spark plug to ignite the mixture gas in the center portion. In a second combustion mode, the control unit controls the fuel injection valve to start a fuel injection on intake stroke so that the mixture gas is formed in the entire combustion chamber, the swirl generating part so that a swirl flow becomes weaker than in the first combustion mode, and the spark plug to ignite the mixture gas before CTDC.

Abstract: A control system for a compression-ignition engine is provided, which includes an engine configured to combust a mixture gas inside a combustion chamber by compression ignition, a fuel injector attached to the engine, a state function adjusting part attached to the engine and configured to adjust at least introduction of fresh air into the combustion chamber, a three-way catalyst provided in an exhaust passage of the engine, a wall temperature acquiring part configured to acquire a parameter related to a temperature of a wall of the combustion chamber, and a controller. A swirl flow is generated inside the combustion chamber to circle along the wall. When the wall temperature of the combustion chamber is below a given wall temperature, the controller sets an air-fuel ratio of the mixture gas substantially to a stoichiometric air-fuel ratio so as to remain within a purification window of the three-way catalyst.

Abstract: According to one or more embodiments, an internal combustion engine may be operated by a method including one or more of the steps of passing a first fuel and a second fuel into a combustion chamber of an engine cylinder to form a fuel mixture, and combusting the fuel mixture with a spark plug to translate the piston housed in the engine cylinder and rotate a crank shaft coupled to the piston. The engine cylinder may include a cylinder head and cylinder sidewalls, and the combustion chamber may be defined at least partially by the cylinder head, the cylinder sidewalls, and the piston. The first fuel may include a greater octane rating than the second fuel. The combustion chamber may include an end gas region and a central region, the central region more near to the spark plug than the end gas region.

Abstract: Methods and systems for providing vacuum to a vehicle are described. In one example, a method adjusts an engine air-fuel ratio in response to provide additional vacuum to the vehicle.

Abstract: A variable charge motion system may include a sliding plate positioned internal to a pipeline of an intake port connected to a combustion chamber, and slide and moved to induce a tumble flow with respect to an intake flow of the air which flows the pipeline and enters into the combustion chamber, wherein the sliding plate is positioned along a guide wall formed in the pipeline.

Abstract: An engine has a cylinder head defining an intake port with a roof defining first and second valve guide bores upstream of first and second siamesed intake valve seats for a cylinder. The head has first and second asymmetric fairings extending outwardly from the roof and positioned directly upstream of respective bores. Each fairing has an inner wall intersecting an outer wall along an upstream edge and an inclined planar roof wall extending between the inner and outer walls. A method of forming the cylinder head and engine is also provided by milling the fairings from a roof preform formed with the intake port of the head.

Abstract: An intake port of an internal combustion engine is connected to a combustion chamber and includes a connecting portion having a passage cross-sectional area that increases as the connecting portion approaches the combustion chamber, and an upstream portion connected to an upstream end of the connecting portion. The connecting portion is provided at its downstream end with a valve seat with which an umbrella part of an intake valve is brought into contact. At least one recess extending in an extending direction of the intake port and included in the connecting portion and the upstream portion is provided at least at one of two portions, the two portions located on both sides in an extending direction of an output shaft, of a peripheral surface of the intake port.

Abstract: An air intake structure for a vehicle engine includes: a variable flap rotatably provided in an intake air passage so as to control a cross-sectional area of intake air flow; a port plate provided to a downstream of the variable flap, and generating displacement in cooperation with the variable flap; a driving unit supplying a driving force for generating displacement of both the variable flap and the port plate; and a controller determining a rotation angle of the variable flap in accordance with an operating range of an engine, and controlling the rotation angle of the variable flap by driving the driving unit.

Abstract: An intake air control apparatus for a vehicle may include a valve flap provided in an air intake passage, the valve flap having a rotation shaft facing opposite sides of the air intake passage, to control a cross-sectional area of air intake flow according to a rotation angle thereof about the rotation shaft; a driving device supplying a driving force to the valve flap; and a port plate being provided in the air intake passage, with a longitudinal direction thereof being in parallel to a longitudinal direction of the air intake passage, the port plate dividing the air intake passage into an upper passage and a lower passage, wherein based on a width direction, at least a portion of the port plate has a height changing portion that changes a height of the port plate from a lower internal wall of the air intake passage.

Abstract: An engine cylinder head is provided. The engine cylinder head includes a portion of a first combustion chamber, an upper coolant jacket portion, and a lower coolant jacket portion directing heat from the first combustion chamber and including a first coolant passage and a second coolant passage, the first coolant passage and the second coolant passage laying along a lateral axis, at least a portion of the first coolant passage separated from the second coolant passage via first and second walls.

Abstract: An intake manifold is provided that controls swirl on entry to a combustion chamber. Each intake manifold includes a fin or rib portion positioned to reduce or eliminate swirl induced by the configuration of the intake manifold, particularly when used in a large engine having a left bank and a right bank of combustion chambers. By controlling swirl induced by the intake manifold, charge motion consistency is improved between engine cylinders and between the left bank and the right bank, thereby improving the consistency of combustion and power output, improving efficiency and reducing emissions (e.g., decreased particulate emissions (also described as smoke), hydrocarbon emissions, and NOx emissions), and further including an improved knock margin, improved fuel economy, wider rich and lean limits, etc.

Abstract: Dual-fuel engine system includes cylinders in which the cylinders have an intake valve and an exhaust valve that control a flow of fluid into and out of a combustion chamber of the corresponding cylinder. The intake valve is configured to have an intake valve closure (IVC) timing. The dual-fuel engine system is configured to operate in a single-fuel mode and a dual-fuel mode. The combustion chamber and a piston are designed to provide a compression ratio. The dual-fuel engine system also includes one or more processors that are operably coupled to and configured to control operation of the first fuel injector. The compression ratio and the IVC timing are selected to achieve a target pre-combustion temperature. The target pre-combustion temperature permits the dual-fuel engine system to operate at a high substitution rate in the dual-fuel mode and at a sufficient fuel efficiency in the single-fuel mode.

Abstract: A method and a device for supplying fuel into a combustion chamber of a cylinder of an internal combustion engine, in which an air-fuel mixture is supplied to the cylinder via at least two intake sections, which are connected to the cylinder via an intake valve, and each of the intake sections is assigned an injector, fuel being injected into the intake sections in at least intermittently asynchronous manner.

Abstract: An internal combustion engine includes a plurality of cylinders, each of which two intake valves and two exhaust valves, respectively arranged in a valve mount of a cylinder head of the internal combustion engine as well as a coolant distributing chamber and a coolant accumulating chamber being associated to. For each cylinder two coolant ducts are formed in the cylinder head and each is fluidly connected to the corresponding coolant distributing chamber and the corresponding coolant accumulating chamber. A first one of the coolant ducts on a first side extends about a first one of the intake valves and on a second side opposite the first side about a first one of the exhaust valves, and a second one of the coolant ducts extends on the first side about a second one of the intake valves and on the second side about a second one of the exhaust valves.

Abstract: An intake device of an engine having cylinders is provided. The intake device includes a cylinder head formed with two intake ports per cylinder, and a forced induction system. One of the two intake ports is designed to have a smaller passage cross-sectional area at a throat portion thereof than that of the other intake port, and to cause a strength of a tumble flow strength of intake air formed within a combustion chamber to be stronger when a flow of the intake air into the combustion chamber is assumed to be caused only from the one of the two intake ports, than only from the other intake port. A tumble ratio of the intake air flow within the combustion chamber is a predetermined value or greater when the intake air is forcibly induced and flows into the combustion chamber from the two intake ports.

Abstract: A control device of a diesel engine is provided. The diesel engine includes an injector for injecting fuel into a cylinder, and a turbocharger for compressing intake air by using exhaust energy. The control device includes a calculating module for setting a basic injection timing determined according to an operating state of the engine, as a timing of injecting the fuel from the injector, and an injection control module for injecting the fuel from the injector at the set basic injection timing at least while the engine is in a steady operation.

Abstract: An exhaust nozzle tip for an exhaust runner conveying a first flow of an exhaust gas includes an inlet, outlet, and nozzle passageway. The inlet receives a second flow of the exhaust gas from an internal combustion engine. The outlet introduces the second flow into the first flow in the exhaust runner. The nozzle passageway conveys the second flow from the inlet to the outlet and is defined by an upstream curved surface, and a downstream surface. The downstream surface includes a first downstream curve, a straight portion, and a second downstream curve. The first downstream curve transitions from perpendicular to the first flow to between 60 degrees and 15 degrees relative to the first flow. The straight portion extends from the first downstream curve. The second downstream curve transitions from the straight portion to a downstream portion of the exhaust runner.

Abstract: An injection nozzle for the direct injection of a liquid fuel into a cylinder chamber of a piston engine includes multiple spray holes for generating injection jets. The multiple spray holes are distributed on a nozzle body of the injection nozzle in the peripheral direction. At least one pair of spray holes adjoining in the peripheral direction is provided, the longitudinal center axes of which enclose a pair angle in the peripheral direction that is smaller than an adjacent angle which is enclosed between the longitudinal center axis of the respective spray hole of the spray hole pair in the peripheral direction and a longitudinal center axis of a spray hole adjoining the spray hole pair in the peripheral direction.

Abstract: The present invention relates to a catalysis apparatus for testing catalysts with variable process pressure adjustment over a pressure range from 0.01 millibar to 300 bar. The apparatus preferably has a plurality of reaction chambers (101, 102, . . . ) arranged in parallel, the reaction chamber outlet-side lines (211, 212, . . . ) of which are divided into two groups of sub-lines. One group of main lines (411, 412, . . . ) is operatively connected to a regulating valve (61), which is common to all of the main lines, and to an exhaust-air line (62), and the second group of secondary lines (311, 312, 313, . . . ) and switching valves (321, 322, . . . ) is operatively connected to an analysis unit (34). It is preferable for reaction chamber outlet-side lines (201, 202, . . . ) to be equipped in each case with a separate line for regulating fluid supply (211, 212, . . . ). In a preferred embodiment, the connecting points of the reaction chamber outlet-side lines (201, 202, . . .

Abstract: A vehicular air intake is configured to produce a turbulent intake air flow in a cylinder of an engine. The air flow may be provided as a vortex. A throttle valve, for controlling an amount of intake air provided to the engine, has a pivot shaft with an axis which is offset from a center axis of an air intake passage in which the throttle valve is installed, and a throttle plate affixed to the pivot shaft. The pivot axis is offset and spaced away from the central axis of the throttle body such that a first portion of a throttle plate disposed on a first side of the pivot shaft, is larger than a second portion of the throttle plate disposed on a second side of the pivot shaft. This arrangement provides the non-uniform turbulent air flow into the engine.

Abstract: The invention relates to a gas supply module (20) for an engine, comprising a heat exchanger (22) capable of cooling gases for the intake thereof in an intake space of a cylinder head of the engine, and a gas supply valve (24) capable of directing said gases toward the intake space of said cylinder head and/or through said heat exchanger (22), said module (20) further comprising an interface element (26) closing said intake space of said cylinder head. According to the invention, said interface element (26) and said valve (24) are shaped such that said valve (24) can be attached to said cylinder head via at least a first attachment means extending through at least the interface element (26). The invention also relates to an assembly of an engine cylinder head and such a module, and to a motor vehicle engine comprising such an assembly. The invention can particularly be used in the field of motor vehicles.

Abstract: A pressure release valve configured to vent excess pressure from an intake manifold. The pressure release valve includes a sealing surface on the intake manifold, a top plate coupled to and spaced from the sealing surface, and a seal plate slidably disposed between the top plate and the sealing surface. The seal plate is configured to move between a closed position and an open position when subject to a pressure exceeding a threshold pressure. The pressure release valve also includes at least one resilient member disposed between the sealing surface and the top plate. The at least one resilient member is adapted to bias the seal plate into the closed position.

Abstract: A gas intake device for letting gases into an inlet volume of a cylinder head of a motor vehicle combustion engine includes a valve (10) for supplying the cylinder head with gas, this valve communicating with the inlet volume of the cylinder head directly and indirectly via a heat exchanger (14). The valve (10) and the heat exchanger (14) are mounted on a plate (21) intended to be mounted directly on the cylinder head. The device is compact and relatively insensitive to vibration.

Abstract: In a premixed compression ignition diesel engine 1 with fuel being injected midway of a intake passage 15, an intake port 6 is formed with an orifice 10 which is throttled in passage cross-sectional area at least in an opening operation of an intake valve 7. This prevents adhesion of the fuel to an inner wall of the intake passage and promotes atomization of the fuel. A combustion chamber is fed with the sufficiently atomized fuel, which prevents combustion failure in the combustion chamber to attain reduction of particulate matters.

Abstract: An internal combustion engine includes a pair of adjacent cylinders, each one of the pair of adjacent cylinders includes a piston, a first intake valve, a second intake valve, a primary port associated with the first intake valve, and a secondary port associated with the second intake valve. Each of the ports is configured to provide a predominant direction of airflow therethrough during engine operation when viewed from above the cylinders and effectively oriented to provide respective in-cylinder air-swirl of opposite direction in each one of the pair of adjacent cylinders during an intake stroke of a respective piston.

Abstract: A spark ignition direct injection fuel cylinder for an engine includes a rotatable valve at a curved wall of an intake duct. The rotatable valve provides a variable step in to adjust the degree of tumble airflow while reducing flow restriction to improve engine performance across operating conditions.

Abstract: An intake system for an internal combustion engine includes a control unit that adjusts the opening amount of a TCV having a valve body and a valve shaft within a valve opening amount range between first and second opening amounts, and first and second rotation restriction portions that prevent the valve body from moving beyond first and second opening amount positions, respectively, by contacting the valve shaft. The valve body is divided into a short valve portion and a long valve portion located upstream of the short valve portion by the valve shaft. The length from the valve shaft to the tip is greater in the long valve portion than in the short valve portion. When the valve body is in the first or second opening position, the valve shaft is pushed against the first or second rotation restriction portion by intake air flowing through an intake pipe.

Abstract: An engine assembly may include a cylinder head, an intake manifold assembly, first and second vanes, and an actuation mechanism. The first and second vanes may be rotatably coupled to the intake manifold assembly. The first vane may be located within an outlet of a first intake passage and the second vane may be located within an outlet of a second intake passage. The first and second vanes may be displaceable from an open position to a closed position. The first vane may extend along a wall defining the first intake passage when in the open position and the second vane may extend along a wall defining the second intake passage when in the open position. The actuation mechanism may be coupled to the first and second vanes to rotate the first and second vanes between the open and closed positions.

Abstract: An engine includes exhaust manifold integrally formed with a cylinder head. The engine may include an exhaust manifold having at least one single exhaust outlet for exhausting exhaust gas that is exhausted from at least two cylinders that are not adjacent with each other, wherein periods during which exhaust valves are open are not overlapped with each other between the at least two cylinders. The exhaust manifold is integrally formed with the cylinder head such that costs can be reduced. Also, the water jacket is formed between the exhaust passages of the exhaust manifold such that the durability of the turbocharger that is affected by a heat load can be improved. Also, the twin scroll turbocharger is directly connected to the exhaust outlet of the manifold such that the compression ratio of the intake air can be effectively improved.

Abstract: A lower intake manifold assembly includes a lower housing and a runner insert fitted into the lower housing. The lower housing may be made of metal and the runner insert may advantageously be made of a synthetic resin material. The runner insert provides a sealing surface between the lower housing and the cylinder head of an internal combustion engine. The runner insert also supports a charge motion control valve flap assembly that advantageously may include a shaft and synthetic resin flaps over-molded onto the shaft.

Abstract: In an engine combustion chamber, a first intake port (19) formed from a straight port has a throat portion (43) formed in a linear shape and opening in a tangential direction of the inner periphery of a cylinder (11a), thus generating a first swirl (S1), and a second intake port (20) formed from a helical port has a throat portion (44) formed in a helical shape, thus generating a second swirl (S2) inside the first swirl (S1) in the same direction as that of the first swirl (S1). In this way, even with the first and second intake ports (19, 20) hardly curved overall, it is possible to efficiently generate first and second swirls (S1, S2) that do not interfere with each other, and it becomes possible to reduce the cost of machining the cylinder head, make the cylinder head compact, and simplify the structure of the cylinder head.

Abstract: An intake air amount controlling apparatus of an engine is provided. The apparatus comprises an intake manifold that is branched from an intake manifold collecting portion of the engine. The intake manifold communicates with an intake port of a cylinder head of a corresponding cylinder. The apparatus further comprises a throttle valve in the intake manifold of the cylinder and a throttle bore provided in the intake manifold. The throttle bore has a curved surface. The throttle valve rotates such that one half of the throttle valve contacts with the curved surface of the throttle bore until the throttle valve reaches a predetermined opening degree. Thus, an air flow via the one half of the throttle valve is prevented from entering the intake port. An air flow via the other half of the throttle valve is allowed to enter the intake port.

Abstract: In an internal combustion engine includes an intake valve port that opens into a combustion chamber on one side of a plane containing the axis of a cylinder bore. An exhaust valve port opens into the combustion chamber on the other side of the plane. A spark plug has a tip end that fronts a substantially central portion of the combustion chamber. The spark plug is disposed between the intake valve and the exhaust valve. In order to restrain the blow-by of an unburned fuel-air mixture, and to suppress the bulging of the cylinder head to the intake system side, the operation axis of an intake valve is set to be substantially parallel to the axis of the cylinder bore. In addition, one side surface of a cylinder head is formed to be substantially parallel to the axis of the cylinder bore.

Abstract: An internal combustion engine wherein the top wall surface of the intake air inflow passage part of the intake port is formed by a first top wall surface and a second top wall surface lower than the first top wall surface and wherein a lower layer flow passage and an upper layer flow passage are formed at the height position of the second top wall surface as a boundary. When the intake valve opens, a lower layer flow flowing through the inside of the lower layer flow passage passes through the intake valve opening region, flows to the circumferential direction of the combustion chamber, and generates a swirl, while an upper layer flow flowing through the inside of the upper layer flow passage passes through the helical part and flows into the combustion chamber.

Abstract: An apparatus for minimizing spark-knock within a combustion chamber of a spark-ignition internal combustion engine, whereby a control vane mounted inside the intake runner is arranged to direct a fuel-air charge to a region inside the combustion chamber where spark-knock has been empirically determined to occur.

Abstract: In an internal combustion engine in which air-intake valves reciprocate in parallel to the direction of reciprocal motion of pistons, an air-intake structure of an internal combustion engine includes an outward projection of the air-intake port that is reduced to achieve a downsizing of a cylinder head. An air-intake structure includes air-intake valves that are supported by a cylinder head having integrally formed air-intake ports so as to reciprocate in parallel with the direction of reciprocal motion of the pistons. Fuel injection devices are formed integrally with a throttle body on intake manifolds to be connected to the air-intake ports. The air-intake ports extend toward the cylinder head cover along a recess formed on the outer surface of the cylinder head that is connected to the intake manifolds at positions just before reaching the identical plane to a mating surface between the cylinder head and the cylinder head cover.

Abstract: A structured combustion chamber for an engine has a cylinder head with an intake hole portion communicating between an intake port and a combustion chamber and an exhaust hole portion which makes a communication between an exhaust port and the combustion chamber, an intake valve for opening and closing the intake hole portion, and a continuous variable valve lift mechanism for lifting the intake valve in a stepless fashion, a flow promoting device is provided to promote a motion of an air current in the combustion chamber when a quantity of lift of the intake valve driven by the continuous variable valve lift mechanism is small and further to suppress a decrease in flow rate of an intake air coming through the intake hole portion into the combustion chamber when the quantity of lift of the intake valve driven by the continuous variable valve lift mechanism reaches a maximum.

Abstract: An integrated valve device includes a casing having intake passages respectively accommodating valves and separately connected with cylinders of an engine. The valves are skewered with a shaft extending through a through hole of each valve along a rotation axis. An actuator generates driving force to rotate the valves via the shaft. The shaft has a fitting portions respectively supporting the valves at mount angles. The mount angle of each valve with respect to each fitting portion is determined correspondingly to load torque applied to each valve toward a valve-open direction when being in a full close position.

Abstract: A reciprocating engine includes a turbocharging unit that: supplies the intake manifold with air via a coolant; is supplied with gas by the exhaust manifold; and has the turbine supply pressure substantially equal to the compressor discharge pressure. At constant air temperature, the turbocharging unit delivers a substantially constant volume of cooled air when the pressure varies, and the volume is substantially proportional to the turbine outlet section. The turbine pressure is maintained substantially equal to compressor pressure by a EGR bypass between the intake and exhaust manifold. In addition, the volume of air is less than the volume drawn in at the speed so that a flow of hot gases is drawn in again via the bypass above the speed, where the volume drawn in is equal to the volume, and a flow of air is deflected towards the turbine below the speed.

Abstract: An air-cooled engine is hung and fixed under a rear part of a backbone of a body frame. The engine is disposed so that the center axis of a cylinder in its cylinder block extends approximately horizontally and so that its cylinder head is directed toward the front. A fuel injection device is located between an intake valve and an intake port in the cylinder head. An injection nozzle of the fuel injection device and an intake valve opening are placed at a short distance. While the vehicle is idling or running at low speed, the vicinity of the tip of an injector of the fuel injection device is cooled by assist air supplied from a throttle body through a secondary passage, and when the vehicle runs normally or at high speed, the fuel injection device is cooled by the wind that hits the cylinder head.

Abstract: Enhanced combustibility by increasing the difference in intake gas velocity between a low flow velocity region and first and second high flow velocity regions in an intake port. An intake port of an internal combustion engine has an intake flow control port portion provided with first and second projecting portions. In the passage cross section of the intake flow control port portion, there are provided a low flow velocity region, and first and second high flow velocity regions formed on either side of and across the low flow velocity region and the first and second projecting portions wherein the maximum flow velocity of intake gas is comparatively larger than that in the low flow velocity region. The intake gas reaches intake ports with a flow velocity distribution having the relationship of the magnitudes of flow velocities in the low flow velocity region and first and second high flow velocity regions.

Abstract: In an internal combustion engine includes an intake valve port that opens into a combustion chamber on one side of a plane containing the axis of a cylinder bore. An exhaust valve port opens into the combustion chamber on the other side of the plane. A spark plug has a tip end that fronts a substantially central portion of the combustion chamber. The spark plug is disposed between the intake valve and the exhaust valve. In order to restrain the blow-by of an unburned fuel-air mixture, and to suppress the bulging of the cylinder head to the intake system side, the operation axis of an intake valve is set to be substantially parallel to the axis of the cylinder bore. In addition, one side surface of a cylinder head is formed to be substantially parallel to the axis of the cylinder bore.

Abstract: An intake port for a 4-cycle engine includes an intake port base integrally formed with a cylinder head, and an intake port forming member that forms an intake port together with the intake port base. The area of the cross section of the intake port orthogonal to a centerline of the intake port is substantially uniform from an open intake side thereof toward a combustion chamber. The angle made by the centerline of the intake port and an intake valve shaft is larger than 90° from a viewpoint of the intake valve. Thereby, the 4-cycle engine can output high power with the intake port shape, as formed with above mentioned configuration, that reduces intake resistance and that uses simple design molds. More specifically, the engine can reliably prevent condensed fuel from remaining in the intake port to avoid incomplete combustion of gas.