Abstract: An internal combustion engine with a supercharger, of a reciprocating piston type, having a supercharger disposed in an intake passage, wherein the relation of a pressure ratio (.gamma.=P/Po) of pressure (P) on the discharge side of the supercharger to atmospheric pressure (Po) at the time of high load with a geometric compression ratio (.epsilon.) of the engine and a cylinder bore size (B), represented by millimeter, satisfies the following formula:.gamma..gtoreq.-0.29.epsilon.+6.0-0.022B.

Abstract: A spark ignition type reciprocating engine of a natural intake system with an ignition plug arranged to face a combustion chamber defined and delimited by a piston inserted into a cylinder so as to move in a reciprocating way, which has:a bore size of the cylinder ranging from approximately 45 mm to 67 mm;a volume of a single chamber of the cylinder ranging from approximately 110 cc to 340 cc;a ratio of a stroke of the piston to the bore size of the cylinder being larger than 1; anda compression ratio of the engine being 11 or larger.

Abstract: An engine-control system is structured in such a way that a timing for closing the intake valve is retarded and the air-fuel ratio is so set as to become a rich air-fuel ratio richer than, for example, the stoichiometric air-fuel ratio, in a region where the load is low. On the other hand, in a region where the load is high, the timing for closing the intake valve is set earlier and the air-fuel ratio is so set as to become a lean air-fuel ratio leaner than, for example, the stoichiometric air-fuel ratio.

Abstract: An internal combustion engine with a supercharger with a piston arranged to be inserted into a cylinder so as to move in a reciprocating way, which has a bore size of the cylinder ranging from approximately 43 mm to 67 mm; a volume of a single chamber of the cylinder ranging from approximately 110 cc to 400 cc; a ratio of a stroke of the piston to the bore size of the cylinder being larger than 1; and a compression ratio of the engine being 9 or larger.

Abstract: A supercharging apparatus for an internal combustion engine comprises an intake air passage communicating with a cylinder of an engine through an intake valve; a mechanical supercharger provided in the intake air passage; a variable valve timing mechanism for varying a closing timing of the intake valve with respect to a bottom dead center of an engine piston; a control unit for controlling the variable valve timing mechanism in accordance with an engine speed at least in a supercharging region wherein the mechanical supercharger is operative to supply supercharged air into the cylinder, in such a manner that the closing timing of the intake valve is switched between an advanced timing and a delayed timing; and an assist intake system for causing a dynamic supercharging effect in the intake air passage when the closing timing of the intake valve is switched to the delayed timing, thereby assisting the mechanical supercharger in a low engine operational region.

Abstract: An engine intake apparatus includes a mechanical supercharger: a plurality of engine cylinders, each of the engine cylinders communicating with an intake air passage through an intake valve and an exhaust gas passage through an exhaust valve; and a variable valve timing mechanism for varying a valve overlap period between the intake and exhaust valves. The variable valve timing mechanism widens the valve overlap period in a predetermined high engine speed region and narrows the valve overlap period in predetermined low engine speed region. When the valve overlap is large, an inertia supercharging effect is generated so that a negative-pressure wave caused during an engine intake stroke propagates in the independent intake air passage from the engine cylinder to an upstream part thereof, in turn, is reflected at a volumetrically enlarged portion and, then, becomes a positive-pressure wave and returns to the engine cylinder.

Abstract: A control system for an engine with a mechanical supercharger supercharges intake air. The control system has a valve timing variable mechanism for varying an opening and closing timing of an intake valve, a fuel injector delivering fuel in an intake stroke of each of the cylinders of the engine in a high load and low speed region of the engine, and a controller for controlling the valve timing variable mechanism. In a high load region of the engine, an overlapping period of an intake valve and an exhaust valve is longer in a high speed region than in a low speed region. A closing time of the intake valve is earlier than a predetermined optimum closing time and a closing time of the intake valve in a high speed region is later than in the low speed region.

Abstract: A controller for a supercharged engine includes a supercharger for supercharging intake air, an intercooler for cooling the intake air discharged from the supercharger, a valve timing varying device for varying valve timing so that an overlapping term, in which both intake and exhaust valves open, is longer when an engine speed is relatively high than when the engine speed is relatively low, and a controller for controlling the valve timing varying device so that when the overlapping term is short at relatively low speed of the engine, the intake valves close at a timing later than a timing at which the intake valves close when the overlapping term is long at relatively high speed of the engine.

Abstract: An internal combustion engine of a spark ignition type is so arranged as to set an air-fuel ratio of a mixed fuel to become substantially stoichiometric in the range of from A/F=13 to A/F=16 at the time of running in a high load region and to recirculate exhaust gases into the intake system. For the internal combustion engine of a natural intake type, the compression ratio is preferably set to 11 or larger; for the internal combustion engine of a supercharging type, the compression ratio is preferably set to 9 or larger. The rate at which the exhaust gases are recirculated is preferably set to be constant or to become larger as the load of the engine becomes larger.

Abstract: The supercharged internal combustion engine is so adapted as to set the air-fuel ratio to become a lean air-fuel ratio which is leaner than stoichiometric and lean enough to maximize improvements in a rate of consumption of fuel, for example, to the A/F ratio of 16, when the supercharger exists in such a supercharging region as demonstrating its sufficient degree of supercharging capability. When the air-fuel ratio is made lean in the supercharging region, exhaust gases are recirculated into the intake system of the engine, in addition to a mixed fuel. Preferably, the exhaust gases having lower temperatures are recirculated at the time of a high load of the engine in the supercharging region, while the exhaust gases having higher temperatures are recirculated at the time of a low load of the engine therein.

Abstract: A mechanical supercharger is provided in an intake manifold, and two inlet ports in communication with a cylinder are provided. A swirl control valve disposed in one of the two inlet ports is opened in a low speed/medium load region, and closed in a low speed/high load region and a low speed/low load region. Accordingly, scavenging performance can be enhanced in the low speed/medium load region where the pressure of a supercharged mixture flow is not sufficiently higher than the pressure of exhaust gas. In the low speed/high load region where the pressure of the supercharged mixture flow is sufficiently higher than the pressure of exhaust gas, undesired blowing of the mixture through a combustion chamber without being used for combustion can be suppressed while ensuring satisfactory scavenging, and an occurrence of knocking can be prevented.

Abstract: An engine control system for controlling an internal combustion engine equipped with a mechanical supercharger includes a valve timing control mechanism which causes first and second intake valves for each cylinder to retard opening and closing of a first intake port with respect to opening and closing of a second intake port. Opening and closing of the first intake port is retarded when a specific range of engine operating conditions, in which the supercharger is operating, is detected.

Abstract: Disclosed is an exhaust gas recirculation system for an engine having a high compression ratio or with a supercharger. An outside EGR duct connecting the exhaust system to the intake system is provided with a first control valve, which has a second outside EGR duct bypassing the first control valve. The second EGR duct has a second EGR control valve and a cooler. When the engine exists in an extremely low load state, the first and second control valves are closed to inhibit the outside EGR. In the light load state, the first control valve is opened while the second control valve is closed, thereby allowing recirculation of the EGR gases having high temperature and reducing the pumping loss.

Abstract: The engine is provided with an auxiliary chamber having an auxiliary chamber port with an opening communicated with the combustion chamber. The auxiliary chamber port is arranged to be opened or closed with an auxiliary chamber valve. The timing of closing the auxiliary chamber valve is in between a final stage of compression stroke in which the temperature within the cylinder becomes higher and an initial stage of explosion stroke. On the other hand, the timing of opening the auxiliary chamber valve is in a middle stage of the compression stroke, thereby allowing the mixed fuel cooled in the auxiliary chamber to be replaced with a portion of the mixed fuel in the combustion chamber, thereby lowering the temperature within the cylinder.

Abstract: An engine induction system includes intake passages connected to inlet ports of an engine, an injector provided in the intake passage for injecting fuel in an intake plenum between the injector and the inlet port, the injector being disposed in such a position that the volume of the intake plenum is greater than the predetermined stroke volume. This ensures improved vaporization and atomization of fuel and mixing of fuel and air, and improves the combustibility and increases the charging efficiency of use of latent heat of vaporization.

Abstract: An intake system for a vehicle for delivering intake air through separate or discrete intake passages of the intake system into engine cylinders through discrete intake passages. A collector chamber and a resonator chamber connect with an upstream main intake passage and the discrete intake passages. The collector chamber communicates at one end with upstream ends of the discrete intake passages and at its another end, opposite to the one end, with the resonator chamber. The discrete intake passages are clustered or grouped together at their upstream ends and connected as a cluster to the collector chamber.

Abstract: An intake manifold for a multi cylinder internal combustion engine has a common upstream passage and individual downstream passages, leading individually to cylinders of the engine, respectively. These individual downstream passages are connected between a downstream end of the common upstream passage and the cylinders. Upstream end portions of the individual downstream passages are symmetrically located around a fuel injector, disposed downstream relative to the common upstream passage, and are joined together. At a center of the symmetrically joined upstream end portions of the individual downstream passages, fuel passages are provided to open independently into the upstream end portions so as to introduce fuel from the fuel injector into the individual downstream passages.

Abstract: Discrete intake passages communicating with respective cylinders of a multiple-cylinder in-line engine are merged into an integrated chamber at their upstream ends. The integrated chamber is disposed above the engine and extends substantially horizontally. Each discrete intake passage extends from the engine body, bends upward toward the integrated chamber and is connected to the downstream side end face of the integrated chamber. The discrete intake passages for the cylinders which are positioned relatively near to the integrated chamber are connected to the downstream side end face of the integrated chamber at an upper portion of the end face and the discrete intake passages for the cylinders which are positioned relatively far from the integrated chamber are connected to the downstream side end face of the integrated chamber at a lower portion of the end face.

Abstract: A control system for an engine with a turbo supercharger includes a first switching device for switching an introduction of intake gas to the engine in accordance with engine speed between a first intake condition, in which a charging efficiency of the intake gas is improved in a lower engine speed condition, and a second intake condition, in which the charging efficiency of the intake gas is improved in a higher engine speed condition. The control system also includes a second switching device for switching a maximum supercharging pressure of the turbo supercharger from a lower pressure to a higher pressure in response to a switching operation between the first intake condition and the second intake condition. An improved charging efficiency of the intake gas can be obtained in a broader range of the engine speeds reducing the maximum supercharging pressure of the intake gas, thereby preventing knocking of the engine.

Abstract: An intake-exhaust control system includes a mechanism for changing timings at which the open periods of intake and/or exhaust valves overlap. A control unit cooperates with the valve timing changing mechanism to cause it to change the timing stepwise so as to vary the valve overlap in time, or in degrees, in a plurality of steps according to engine operating conditions, such as engine speed and engine load. The valve overlap, when the engine operates under medium or moderate engine speeds, is varied so as to be larger or longer under medium engine loads than under higher or heavier and lower or lighter engine loads.