Abstract: Methods and systems are provided for an engine for adjusting cylinder parameter settings to optimize engine output during a transient mode. In one example, a method may include adjusting cylinder parameter settings, including a cam timing setting, a spark timing setting, and a fuel injection timing setting based on a chamber temperature in response to a rate of fuel injection acceleration being greater than a positive threshold, thus indicating the engine is in the transient mode.

Abstract: The split cycle engine of the present disclosure comprises a compression cylinder (10) accommodating a compression piston (12), a combustion cylinder (20) accommodating a combustion piston (22), a recuperator (35) arranged to exchange heat between exhaust fluid (95) from the combustion cylinder and working fluid being supplied from the compression cylinder to the combustion cylinder via a crossover passage (30). A controller is configured to control operation of the engine based on an indication of a temperature of at least one of a material of the recuperator and the working fluid in the crossover passage.

Abstract: A split cycle internal combustion engine includes a combustion cylinder accommodating a combustion piston and a compression cylinder accommodating a compression piston. The engine also includes a controller arranged to receive an indication of a parameter associated with the combustion cylinder and/or a fluid associated therewith and to control an exhaust valve of the combustion cylinder in dependence on the indicated parameter to cause the exhaust valve to close during the return stroke of the combustion piston, before the combustion piston has reached its top dead centre position (TDC), when the indicated parameter is less than a target value for the parameter; and close on completion of the return stroke of the combustion piston, as the combustion piston reaches its top dead centre position (TDC), when the indicated parameter is equal to or greater than the target value for the parameter.

Abstract: Methods and systems are provided for a cooling system. In one example, a cooling system comprises a device for regulating a coolant flow, where the device is in force-fit connection to a plurality of crankshafts, each crankshaft corresponding to a single cylinder of a plurality of cylinders. The cooling system further comprises a plurality of injectors for injecting coolant onto outer surfaces of the plurality of injectors.

Abstract: A split cycle internal combustion engine includes a combustion cylinder accommodating a combustion piston and a compression cylinder accommodating a compression piston. The engine also includes a controller arranged to receive an indication of a parameter associated with the combustion cylinder and/or a fluid associated therewith and to control an exhaust valve of the combustion cylinder in dependence on the indicated parameter to cause the exhaust valve to close during the return stroke of the combustion piston, before the combustion piston has reached its top dead centre position (TDC), when the indicated parameter is less than a target value for the parameter; and close on completion of the return stroke of the combustion piston, as the combustion piston reaches its top dead centre position (TDC), when the indicated parameter is equal to or greater than the target value for the parameter.

Abstract: There is provided an internal combustion engine control apparatus that is capable of determining accurately from an ignition discharging time period whether the intake valve and the exhaust valve are in the operative condition or in the inoperative condition. A cylinder deactivation controller causes a first ignition controller to perform a first ignition control on the basis of the ignition timing when issuing no cylinder deactivation request, and causes a second ignition controller to perform a second ignition control on the basis of an energizing time period when issuing the cylinder deactivation controller. The discharging time period is calculated by a discharging time period calculation section on the basis of an ion current signal output from the ignition coil.

Abstract: An engine system having an exhaust gas recirculation (EGR) apparatus includes: an engine including a plurality of combustion chambers; an intake line through which an intake gas supplied to the combustion chambers flows; an exhaust line in which an exhaust gas discharged from the combustion chambers flows; and a turbocharger including: a turbine disposed at the exhaust line and rotating by the exhaust gas; and a compressor disposed in the intake line and rotating and compressing external air. The EGR apparatus includes a recirculation line branched from the exhaust line; an EGR valve disposed at the recirculation line and adjusting a recirculation gas amount; a pressure sensor disposed at a front end of the EGR valve to measure a pressure of a recirculation gas; and a flow rate adjustment apparatus disposed at a rear end of the EGR valve and adjusting the recirculation gas amount.

Abstract: A method for improving the efficiency of an internal combustion engine having a cycle, for each cylinder of the engine, including intake, compression, power, and exhaust strokes, comprises inserting two strokes into the cycle in addition to the intake, compression, power, and exhaust strokes. No material other than air is introduced into each cylinder during either of the additional two strokes. A high efficiency internal combustion engine system having a cycle, for each cylinder of the engine, including intake, compression, power, and exhaust strokes, comprises a cylinder, a piston, an air intake device, a fuel injector, an exhaust valve device, a camshaft, and an electronic control unit (ECU) configured to control cylinder operation such that two strokes, in addition to the intake, compression, power, and exhaust strokes, are inserted into the cycle. No material other than air is introduced into each cylinder during either of the additional two strokes.

Abstract: Methods and systems are provided for reducing late burn induced cylinder pre-ignition events. Forced entry of residuals from a late burning cylinder into a neighboring cylinder may be detected based on engine block vibrations sensed in a window during an open exhaust valve of the late burning cylinder. In response to the entry of residuals, a pre-ignition mitigating action, such as fuel enrichment or deactivation, is performed in the neighboring cylinder.

Abstract: A supercharged internal combustion engine having at least two exhaust-gas turbochargers is provided. The engine includes a first exhaust manifold and a second exhaust manifold which are permanently connected to one another upstream of the two turbines of the turbochargers via at least one connecting duct which cannot be closed off. In this way, overflow of exhaust from the one exhaust manifold may be transferred to the other exhaust manifold.

Abstract: An example for operating a spark ignition engine comprises discharging exhaust gases via an exhaust system comprising exhaust pipes from the at least two cylinders coming together to form an exhaust manifold; and initiating autoignition with exhaust gas from a first, exhaust-gas-supplying cylinder, which is discharged from the first cylinder into the exhaust system, the exhaust gas is introduced into an adjacent, exhaust-gas-receiving cylinder via the exhaust system. Exhaust gas from the first cylinder mixes with the air-fuel mixture of an adjacent cylinder raising the temperature therein. Under high loads the higher temperature and density of the aircharge is suitable to undergo autoignition.

Abstract: A fouling free clean EGR system for a diesel-gasoline dual fuel powered engine allows re-circulation of an exhaust gas of a certain cylinder among a plurality of cylinders. The fouling free clean exhaust gas recirculation (EGR) system for a diesel-gasoline dual fuel powered engine in which gasoline and air are pre-mixed and supplied to cylinders and then a diesel fuel is injected and combusted together comprises a directly-exhaust cylinder of which an exhaust valve of the cylinder is connected to an exhaust manifold directly connected to a after treatment device; and an EGR cylinder of which an exhaust valve of the cylinder is connected to an EGR line and which supplies the EGR gas to the diesel-gasoline dual fuel powered engine.

Abstract: A fuel introduction system introduces fuel to an internal combustion engine operating on a six-stroke combustion cycle including a first compression stroke, a first power stroke, a second compression stroke, and a second power stroke. The fuel introduction system includes a first orifice set for introducing a first fuel charge to a combustion chamber of the engine during the first compression stroke and/or power stroke and a second orifice set for introducing a second fuel charge to the combustion chamber during the second compression stroke and/or power stroke. Combustion of the second fuel charge can assist in burning particulate matter left in the combustion chamber from combusting the first fuel charge. The first and second orifice sets can be configured to differentiate the first and second fuel charges by, for example, fuel quantity or spray pattern.

Abstract: A system is disclosed for a four-stroke internal combustion engine comprising: at least two cylinders; a fuel direct injection device; a variable valve timing system; an engine controller to control valve timing according to load; wherein, below a lower load threshold, a first cylinder is deactivated, an injection of fuel takes place into a combustion chamber of the first cylinder and an inlet valve of the first cylinder is open during a compression stroke. The opening of the inlet valve during a compression stroke of the first cylinder when deactivated allows the substantially homogenous air-fuel mixture therein to escape into the intake manifold and be made available to the second and active cylinder.

Abstract: Various systems and method for controlling exhaust gas recirculation in an internal combustion engine are provided. In one embodiment, a method for controlling an engine includes determining an actual intake oxygen concentration, adjusting a donor cylinder fuel injection amount to drive the actual intake oxygen concentration to a designated intake oxygen concentration, and adjusting a non-donor cylinder fuel injection amount dependent upon the donor cylinder fuel injection adjustment and to maintain a second operating parameter.

Abstract: An internal combustion engine includes a first cylinder having an intake valve in fluid communication with an intake manifold, and a second cylinder having an exhaust valve in fluid communication with an exhaust manifold. A transfer passage fluidly connects the first cylinder with the second cylinder. A first fuel injector is configured to provide a first fuel to the first cylinder, and a second fuel injector is configured to provide a second fuel to the second cylinder. The first cylinder operates, at times, to push a first air/fuel mixture through the transfer passage into the second cylinder. The second fuel injector is configured to provide at least one fuel injection plume into the first air/fuel mixture.

Abstract: An internal combustion engine utilizing an additional vapor expansion piston/cylinder to capture traditionally rejected energy. Hot combustion gases from the combustion process are used to power an additional vapor expansion cycle in a separate cylinder from the combustion cycle. Comprised of at least two pistons/cylinders (one fuel combustion and one vapor expansion) diametrically opposed; where the reciprocal motion of the pistons is transferred to the output shaft via a multiple-lobed rotor assembly.

Abstract: A method using exhaust gas recirculation (EGR) in an internal combustion engine. The engine has at least one “dedicated EGR cylinder”, whose entire exhaust is recirculated back to all the engine cylinders. The dedicated EGR cylinder is operated at a rich air-fuel ratio, and the other cylinders are operated stoichiometrically so that a conventional three way catalyst may be used to treat the exhaust. A fuel injector is used to inject fuel into the combustion chamber of the dedicated EGR cylinder after initiation of the main combustion event. This post injection method overcomes flammability limits of a dedicated EGR cylinder, and increases the hydrogen (H2) and carbon monoxide (CO) in its exhaust.

Abstract: An internal combustion engine comprises a cylinder configured to operate on a four-stroke combustion cycle, a dedicated EGR cylinder configured to operate on a two-stroke combustion cycle and an EGR supply conduit extending between an exhaust port of the dedicated EGR cylinder and the cylinder configured to operate on a four-stroke combustion cycle for delivery of exhaust gas exiting the dedicated EGR cylinder to the cylinder configured to operate on a four-stroke combustion cycle for combustion therein.

Abstract: An internal combustion engine has four cylinders, each having a respective piston positioned therein and connected with a crankshaft for movement in the respective cylinder. Each cylinder has a plurality of ports with a plurality of valves openable and closable to control fluid flow into and out of the cylinder through the ports. Combustion occurs in a first two of the four cylinders (power cylinders) that are each interconnected between a second two of the four cylinders (inductor cylinders) via passages connecting ports of the respective cylinders. Opening and closing of the valves is timed to accomplish internal exhaust gas recirculation, i.e., such that fluid directed from the power cylinders to the inductor cylinders via the passages after combustion is redirected via the passages from the inductor cylinders to the power cylinders. A method of internal exhaust gas recirculation for an engine as described above is also provided.

Abstract: Disclosed is an engine system with a reformer, the engine system comprising a reformer and driving an engine using, as a fuel, a reformed fuel produced by reforming pre-reformed fuel with the reformer, in which the reformer is connected with both a pre-reformed fuel supply adjustment unit which adjusts the amount of the pre-reformed fuel supplied to the reformer and a reformed fuel supply adjustment unit which adjusts the amount of reformed fuel supplied to the engine, and the reformer is installed adjacent to the engine combustion chamber via the reformed fuel supply adjustment unit.

Abstract: A diesel engine system includes a cylinder, an exhaust manifold, an exhaust gas recirculation (EGR) manifold, and a valve. The exhaust manifold is fluidly coupled with the cylinder and directs exhaust generated in the cylinder to an exhaust outlet that delivers the exhaust to an external atmosphere. The EGR manifold is fluidly coupled with the cylinder and recirculates the exhaust generated in the cylinder back to the cylinder as at least part of intake air that is received by the cylinder. The valve is disposed between the cylinder and the exhaust manifold and between the cylinder and the EGR manifold. The valve has a donating mode and a non-donating mode. The valve fluidly couples the cylinder with the EGR manifold when the valve is in the donating mode and fluidly couples the cylinder with the exhaust manifold when the valve is in the non-donating mode.

Abstract: The horizontally opposed center fired engine improves on the traditional design of the horizontally opposed engines and center fired engines with a better engine geometry. The present invention utilizes four pairs of opposing pistons to compress a larger volume of air-fuel mixture within four different cylinders. The four different cylinders are radially positioned around a center axle in order to achieve a perfectly symmetric engine geometry. The center axle consists of two different shafts spinning in two different directions, which could drastically reduce engine vibrations in the present invention. Engine vibrations are caused by a change in engine speed and result in a loss of energy. Due to the design, the present invention will only experience energy loss in the form of entropy and friction. Thus, the present invention can convert a higher percentage of chemical energy into mechanical energy than any other internal combustion engine.

Abstract: The present invention provides a Mackay tri-expansion cycle engine which operates with an eight-stroke master cylinder and an eight-stroke slave cylinder; the Mackay tri-expansion cycle engine intakes air and fuel into the eight-stroke master cylinder, and the air-fuel-mixture combusts in three expansion processes; the first expansion process generates power at high temperature with a hot-combustion-medium of high CO concentration; the second expansion process generates power with a cold-expansion-medium mixing from said hot-combustion-medium and a compressed air, spontaneously converting all CO content into CO2 at a controlled expansion temperature; the third expansion process generates power with a steam-rich expansion-medium at a controlled expansion temperature, in which a calculated amount of water-mixture is injected to absorb heat energy and produce steam, at same time reacting with any remained NOX, HC, and PM to reduce air-pollution from combustion process.

Abstract: An EGR system for an IC engine, wherein the IC engine includes a block defining a plurality of combustion cylinders, a plurality of multi-valve heads, each multi-valve head associated with a respective combustion cylinder and including an inlet valve and an exhaust valve, an exhaust manifold fluid coupled with each exhaust valve, and an intake manifold fluidly coupled between the exhaust manifold and each inlet valve. The EGR system includes: a plurality of EGR inlet valves and a plurality of EGR exhaust valves, wherein each multi-valve head includes at least one EGR inlet valve and at least one EGR exhaust valve; an EGR exhaust manifold fluidly coupled with each EGR exhaust valve; and an EGR intake manifold fluidly coupled between the EGR exhaust manifold and each EGR inlet valve.

Abstract: Improved exhaust gas recirculation system and methods that use one or more of the engine's cylinders as dedicated EGR cylinders. All of the exhaust from the dedicated EGR cylinders is recirculated back to the engine intake. Thus, the EGR rate is constant, but the EGR mass flow may be controlled by adjusting the air-fuel ratio of the dedicated EGR cylinders or by using various variable valve timing techniques.

Abstract: A method is disclosed for operating an engine with a first cylinder providing a net flow of gases from the intake to the exhaust while combusting; and a second cylinder providing a net flow of gases from the exhaust to the intake. Both the first and second cylinders may carry out combustion during such operation.

Abstract: A method is disclosed for operating an engine with a first cylinder providing a net flow of gases from the intake to the exhaust while combusting; and a second cylinder providing a net flow of gases from the exhaust to the intake. Both the first and second cylinders may carry out combustion during such operation.

Abstract: A method is disclosed for operating an engine with a first cylinder providing a net flow of gases from the intake to the exhaust while combusting; and a second cylinder providing a net flow of gases from the exhaust to the intake. Both the first and second cylinders may carry out combustion during such operation.

Abstract: An engine is operated with a first cylinder to provide a net flow of gases from the engine intake to the engine exhaust while a second cylinder returns combusted gases back to the intake to control a timing of auto-ignition combustion in the first cylinder.

Abstract: In one aspect of the disclosure an internal combustion engine may be provided that may include a combustion chamber and a piston reciprocally moveable in the combustion chamber. The combustion chamber may have an intake port and a dual function port. The dual function port may be connected to an exhaust system and to an intake system. A method may be provided including opening a fluid connection between the intake system and the combustion chamber via the intake port as well as the dual function port during at least a part of an intake stroke of the piston. Instead of, or in addition, the method may include opening a fluid connection between the exhaust system and the combustion chamber via the dual function port during at least a part of the intake stroke of the piston.

Abstract: An engine is operated with a first cylinder to provide a net flow of gases from the engine intake to the engine exhaust while a second cylinder returns combusted gases back to the intake to control a timing of auto-ignition combustion in the first cylinder.

Abstract: A method for controlling exhaust gas recirculation is presented. In one embodiment, exhaust gases are routed from the exhaust manifold through a cylinder and into an intake manifold. In some embodiments, the method may be used when a large amount of EGR is desired.

Abstract: A motor has an engine block with cylinders arranged to fire in a firing order. A recirculation system delivers combusted mixture from a cylinder which has just fired to at least partly mix with fuel for the next cylinder in the firing order. Injector bodies (401-405) are associated with each cylinder. Each injector body (401-405) has an internal chamber (424) in communication with a fuel inlet port (426) for delivering fuel into the internal chamber, a fuel outlet port (428) for delivering fuel under pressure from the chamber into the associated cylinder and a combusted mixture out-let port (442). The combusted mixture outlet port (442) of each injector body (401-405) is fluidly connected to the combusted mixture inlet port (438) of the next cylinder in the firing order. Alternatively, the recirculation system is arranged substantially internally within the cylinder head.

Abstract: The present invention provides an engine capable of increasing an introducing amount of an EGR gas without reducing an introducing amount of a fresh air. In an engine structured to introduce fresh air and an EGR gas into a cylinder, the EGR gas is introduced into the cylinder at least at a part of a compression stroke using a pressure in a combustion chamber at least at a part of a power stroke.

Abstract: An invention is provided for an internal combustion engine having a trunnion twin firing cylinder put in tandem for application of 4-6-8 cylinders as needed, including three moving parts, cylinder, piston rod, and crank that fires two pistons during up stroke while having a wet sump, cylinders are perpendicular to the crank and are enclosed at the bottom allowing four strokes every revolution with double firing pistons. The pistons do not require a wrist pin, and the pistons and rod assembly are one piece, pushing straight on the crank throw, eliminating piston side thrust, and reducing conical wear to rings with blow by. A conventional four cylinder engine at 1000 rpm fires 4,000 times in one minute. The trunnion twin firing cylinder engine with four pistons fires 8,000 times in one minute.

Abstract: A system and method for providing exhaust gas to an EGR-equipped lean burn diesel engine (the primary engine). The exhaust gas is provided by a secondary internal combustion device, whose configuration, thermal cycle, and operating conditions may be different from that of the primary engine. The secondary internal combustion device may receive recirculated exhaust gas, fresh air, or some combination of both.

Abstract: The present invention provides a swirl-injection type eight-stroke engine capable of constantly varying the injection-direction of the high-density-air from the slave cylinder, thereby effectively circulating the high-density-air around the master cylinder wall and master cylinder head during the injection process to speed up the mixing of the high-density-air and the hot combustion medium in the master cylinder, furthermore the hot spots in the master cylinder head and the master cylinder wall are eliminated with the two-direction swirling effect during the cold-expansion process.

Abstract: The fuel efficiency of an internal combustion reciprocating piston engine may be increased through selective secondary expansion of exhaust gas in the engine cylinders in order to recover exhaust gas energy which is otherwise wasted by cylinder blow-down at the end of the power stroke. Exhaust valve cam switching, intake valve deactivation, multiple exhaust valves, a specialized exhaust manifold arrangement and an exhaust gas diverter valve can be configured to enable a reciprocating engine to selectively operate in efficient eight stroke cycle compound mode when moderate engine power is demanded, then revert to conventional four stroke cycle non-compound mode operation when high engine power is demanded, without stopping the engine.

Abstract: The invention relates to an internal combustion engine comprising at least two cylinders, at each of which at least one inlet for at least one combustion ingredient is provided. The engine comprises communication means, adapted to provide communication between at least a first of the cylinders, at which a first piston is provided, and a second of the cylinders, at which a second piston is provided, during at least a part of an engine operation period starting during a movement of the first piston towards a bottom dead center (BDC) position at a work stroke of the first cylinder and ending during a movement of the first piston away from the bottom dead center (BDC) position, during which engine operation period the second piston moves towards a bottom dead center (BDC) position and/or away from the bottom dead center (BDC) position.

Abstract: An engine has a crankshaft, rotating about a crankshaft axis of the engine. An expansion piston is slidably received within an expansion cylinder and operatively connected to the crankshaft such that the expansion piston reciprocates through an expansion stroke and an exhaust stroke of a four stroke cycle during a single rotation of the crankshaft. A compression piston is slidably received within a compression cylinder and operatively connected to the crankshaft such that the compression piston reciprocates through an intake stroke and a compression stroke of the same four stroke cycle during the same rotation of the crankshaft. A ratio of cylinder volumes from BDC to TDC for either one of the expansion cylinder and compression cylinder is fixed at substantially 26 to 1 or greater.

Abstract: The invention is directed to a novel self-supercharging internal combustion engine with two pairs of three pistons and cylinders. A self-supercharging internal combustion engine comprising: (a) a first piston and cylinder with intake and exhaust valves, the piston being connected to a crankshaft; (b) a second piston and cylinder with intake and exhaust valves, the piston being connected to the crankshaft; (c) a third piston and cylinder of a size which is at least double the size of the first and second pistons, the third piston having a valve which enables air and fuel to be drawn into the cylinder, the third cylinder being connected to the intake valves of the first and second pistons and cylinders, the third piston being connected to the same crankshaft as the first and second pistons, and a corresponding second set of three pistons and cylinders, the three pistons being connected to a second crankshaft, each crankshaft being interconnected by meshing gears.

Abstract: An internal combustion engine, having a cylinder with a translating piston therein, employs a holding tank connecting, via a valve, to the combustion chamber of the cylinder for receipt of a portion of the engine gasses expelled during a compression stroke for providing that the expansion ratio of an expansion stroke is greater than the compression ratio of the compression stroke. The holding tank is located within a head of the cylinder, and has a single port serving for both ingress and egress of gasses to the combustion chamber. The holding tank is provided with one or more additional passages for connection to one or more additional cylinders in the event that the holding tank is shared among two or more cylinders.

Abstract: A four-cycle internal combustion engine is constructed such that a structure around a cylinder head is not complicated even though the engine has a plurality of cylinders, fuel consumption is improved, and nitrogen oxides are reduced. The engine has cylinder-sided passages, through which burnt gasses pass. Also, the engine includes an inter-cylinder passage in communication with the cylinder-sided passages.

Abstract: The present invention is a second kind of High Efficiency Integrated Heat Engine, or HEIHE-2 for short. HEIHE-2 is a reciprocal combustion engine integrated with both compound cycle and combined cycle. HEIHE-2 comprises triple compound cylinder structure, with the first cylinder and the second cylinder being the primary combustion and/or expansion cylinders; and the third cylinder being the secondary combustion and/or expansion cylinder. Power strokes driven by expansions of different working fluids such as air-fuel combustion products, steam and compressed air, are integrated into one engine block. Triple cylinder structure provides compound expansions of three (3) different fluids as to recover the energies that would be lost with the exhaust fluids or during braking. All of these make HEIHE-2 work around four (4) periods with six (6) different operation strokes. All four (4) working periods contain four (4) different power strokes but only two (2) of them consume the fuel.

Abstract: A split-cycle water injection engine includes a crankshaft rotatable about a crankshaft axis. A power piston is slidably received within a power/expansion cylinder and operatively connected to the crankshaft. A compression piston is slidably received within a compression cylinder and operatively connected to the crankshaft. A crossover passage is operatively connected between the compression cylinder and the power/expansion cylinder and selectively operable to receive compressed air from the compression cylinder and to deliver compressed air to the power/expansion cylinder for use in transmitting power to the crankshaft during engine operation. Valves selectively control gas flow into and out of the compression and power cylinders. A water injector is associated with and adapted to inject water into at least one of the compression cylinders the crossover passage and the power cylinder during engine operation.

Abstract: The invention relates to an internal combustion engine comprising at least two cylinders, at each of which at least one inlet for at least one combustion ingredient is provided. The engine comprises communication means, adapted to provide communication between at least a first of the cylinders, at which a first piston is provided, and a second of the cylinders, at which a second piston is provided, during at least a part of an engine operation period starting during a movement of the first piston towards a bottom dead center (BDC) position at a work stroke of the first cylinder and ending during a movement of the first piston away from the bottom dead center (BDC) position, during which engine operation period the second piston moves towards a bottom dead center (BDC) position and/or away from the bottom dead center (BDC) position.

Abstract: For the purpose of improving the fuel efficiency by lean combustion and enhancing the fuel efficiency improvement effects by performing compression ignition efficiently in some cylinders, a multi-cylinder spark ignition engine is constructed such that exhaust gas, that is exhausted from preceding cylinders 2A, 2D on the exhaust stroke side among pairs of cylinders whose exhaust stroke and intake stroke overlap in a low load, low rotational speed region, is directly introduced through an inter-cylinder gas passage 22 into following cylinders 2B, 2C on the intake stroke side and only gas exhausted from the following cylinders 2B, 2C is fed to an exhaust passage 20, which is provided with a three-way catalyst 24.

Abstract: The invention is intended to provide improved emission-cleaning performance by use of a three-way catalyst alone, without the need for a lean NOx catalyst, while ensuring a fuel economy improvement effect of lean burn operation. A multicylinder spark-ignition engine is constructed such that, in a pair of preceding and following cylinders whose exhaust and intake strokes overlap each other, burned gas discharged from the preceding cylinder (2A, 2D) which is currently in the exhaust stroke is introduced directly into the following cylinder (2B, 2C) which is currently in the intake stroke through an intercylinder gas channel (22) and gas discharged from only the following cylinder (2B, 2C) is led to an exhaust passage (20) provided with a three-way catalyst (24) in a low-load, low-speed operating range.

Abstract: In a pair of preceding and following cylinders whose exhaust and intake strokes overlap each other, intake air supplied to the preceding cylinder (2A, 2D) is supercharged by a turbocharger (23) to produce combustion at a “lean” air-fuel ratio in the preceding cylinder (2A, 2D), and burned gas discharged from the preceding cylinder (2A, 2D) is introduced into the following cylinder (2B, 2C) through an intercylinder gas channel (22). Combustion in the following cylinder (2B, 2C) is made at an air-fuel ratio equal to or smaller than the stoichiometric air-fuel ratio by supplying fuel to the burned gas of a “lean” air-fuel ratio introduced from the preceding cylinder (2A, 2D), and gas discharged from the following cylinder (2B, 2C) is led to an exhaust passage (20) provided with a three-way catalyst (30).