Abstract: A direct fuel injection internal combustion engine having an injector for directly injecting fuel into a combustion chamber thereof is provided. The engine is configured so that a tumble flow is generated in the combustion chamber. A fuel injection by the injector can be performed in a first injection mode and a second injection mode, the first injection mode being a mode in which the fuel injection is completed after the tumble flow is generated, and the second injection mode being a mode in which the fuel injection is completed before the tumble flow is generated. The fuel injection of the first injection mode is performed before completion of the warming-up of the engine, and the fuel injection of the second injection mode is performed after completion of the warming-up of the engine.

Abstract: A control system for an internal combustion engine, which is capable of controlling fuel injection valves while causing valve-closing delay time periods, which occur with the valves actually mounted on the engine, to be reflected thereon, thereby making it possible to improve exhaust emission characteristics and fuel economy performance. The ECU of the control system performs initial value-specific control in fuel injection control and ignition timing control, such that initial value acquisition conditions are satisfied, so as to calculate the initial values of the valve-closing delay time periods when the initial value acquisition conditions are satisfied. When normal-time control is performed, the valve-opening time periods of the valves are calculated using the initial values of the valve-opening time periods, and the valves are controlled to be open over the valve-opening time periods.

Abstract: An internal combustion engine control device to control a fuel injection valve includes: valve-close delay time acquisition circuitry configured to acquire a valve-close delay time of the fuel injection valve; first learning value calculation circuitry configured to calculate a first learning value based on the valve-close delay time when a running state of an internal combustion engine satisfies a predetermined learning condition; valve-open time calculation circuitry configured to calculate a valve-open time of the fuel injection valve based on the first learning value; second learning value calculation circuitry configured to calculate a second learning value based on the valve-close delay time irrespective of the running state of the internal combustion engine; and learning state determination circuitry configured to determine a learning state of the first learning value based on a relationship between the first learning value and second learning value.

Abstract: An internal combustion engine control device to control a fuel injection valve includes: valve-close delay time acquisition circuitry configured to acquire a valve-close delay time of the fuel injection valve; first learning value calculation circuitry configured to calculate a first learning value based on the valve-close delay time when a running state of an internal combustion engine satisfies a predetermined learning condition; valve-open time calculation circuitry configured to calculate a valve-open time of the fuel injection valve based on the first learning value; second learning value calculation circuitry configured to calculate a second learning value based on the valve-close delay time irrespective of the running state of the internal combustion engine; and learning state determination circuitry configured to determine a learning state of the first learning value based on a relationship between the first learning value and second learning value.

Abstract: A control system for an internal combustion engine, which is capable of controlling fuel injection valves while causing valve-closing delay time periods, which occur with the valves actually mounted on the engine, to be reflected thereon, thereby making it possible to improve exhaust emission characteristics and fuel economy performance. The ECU of the control system performs initial value-specific control in fuel injection control and ignition timing control, such that initial value acquisition conditions are satisfied, so as to calculate the initial values of the valve-closing delay time periods when the initial value acquisition conditions are satisfied. When normal-time control is performed, the valve-opening time periods of the valves are calculated using the initial values of the valve-opening time periods, and the valves are controlled to be open over the valve-opening time periods.

Abstract: A fuel injection device for an internal combustion engine including a cylinder, includes a fuel injection valve and a processor. The fuel injection valve injects fuel directly into the cylinder. The fuel injection valve has an injection hole which has a diameter and a length in an axial direction of the injection hole. A ratio of the length to the diameter being 1.0 or smaller. The processor is configured to determine, in a cold operation of the internal combustion engine, a fuel injection time during which the fuel injection valve continues to inject fuel such that an amount of soot in exhaust gas is less than an amount of soot in exhaust gas if the fuel injection valve has the ratio larger than 1.0.

Abstract: A direct fuel injection internal combustion engine having an injector for directly injecting fuel into a combustion chamber thereof is provided. The engine is configured so that a tumble flow is generated in the combustion chamber. A fuel injection by the injector can be performed in a first injection mode and a second injection mode, the first injection mode being a mode in which the fuel injection is completed after the tumble flow is generated, and the second injection mode being a mode in which the fuel injection is completed before the tumble flow is generated. The fuel injection of the first injection mode is performed before completion of the warming-up of the engine, and the fuel injection of the second injection mode is performed after completion of the warming-up of the engine.

Abstract: An oxygen sensor is disposed downstream from a catalyst for purifying exhaust gas from an internal combustion engine and which can suppress an influence of unburnt hydrocarbon on an output voltage. After forming a platinum thin film on the outer periphery of a zirconia ceramic body, only a detection electrode of the ceramic body is dipped in a silver nitrate aqueous solution of 0.1 mol/l, and the silver nitrate is pyrolyzed through a heat treatment. Subsequently, a platinum reference electrode is formed on the inner periphery of the ceramic body. To protect the silver-doped detection electrode, a protective layer is formed on the surface of the detection electrode. By the exposure to combustion gas and through aging, a detection element is formed, and set into a metal case together with a cylindrical heater, to complete an oxygen sensor to be disposed downstream from a CNG engine catalyst.

Abstract: An oxygen sensor is disposed downstream from a catalyst for purifying exhaust gas from an internal combustion engine and which can suppress an influence of unburnt hydrocarbon on an output voltage. After forming a platinum thin film on the outer periphery of a zirconia ceramic body, only a detection electrode of the ceramic body is dipped in a silver nitrate aqueous solution of 0.1 mol/l, and the silver nitrate is pyrolyzed through a heat treatment. Subsequently, a platinum reference electrode is formed on the inner periphery of the ceramic body. To protect the silver-doped detection electrode, a protective layer is formed on the surface of the detection electrode. By the exposure to combustion gas and through aging, a detection element is formed, and set into a metal case together with a cylindrical heater, to complete an oxygen sensor to be disposed downstream from a CNG engine catalyst.

Abstract: There is disclosed an oxygen sensor disposed before an exhaust gas purifying catalyst of an engine which uses a hydrocarbon containing fuel with a H/C ratio of three or more. An oxygen sensor 1 is provided with a solid electrolytic body 2 which can generate a difference in oxygen concentration with reference gas and measured gas, a reference electrode 3 and a detection electrode 4 formed on inner and outer surfaces of the solid electrolytic body 2, and a porous protective layer 5 for covering the detection electrode 4. The detection electrode 4 is formed only of a metal like Pt which promotes oxidizing reaction of methane to have a thickness of 1 to 2 &mgr;m. In the protective layer 5, only a second protective layer 5b carries Pt catalyst 6 which promotes oxidizing reaction of hydrogen, and the amount of carried catalyst is in the range of 0.5 to 7 mol % relative to the whole of the second protective layer 5b.

Abstract: An oxygen sensor is disposed behind an exhaust gas purifying catalyst for an internal combustion engine and which suppresses the influence of unburnt hydrocarbon on the output voltage. A sensor element 1 is provided with a detection electrode 4 on the outer face of a zirconia ceramic body 2, a reference electrode 3 on the inner face of the ceramic body 2 and a spinel protective layer 5 on the outer surface of the detection electrode 4. The tip end of the sensor element 1 is covered with a protective cover 10 which is provided with an outer partition wall 11 having through holes 11a and an inner partition wall 12 having through holes 12a. In a case where the pressure difference between the inside and outside of the protective cover 10 is &Dgr;P(atm) when the atmospheric air with a volume flow rate Q(L/min) is passed into the protective cover 10 from the outside, the ratio &Dgr;P/Q2 is 3.2×10−5 (atm·min2·L−2).

Abstract: An oxygen concentration sensor abnormality-detecting system is provided for an internal combustion engine having first and second oxygen concentration sensors arranged in the exhaust system upstream and downstream of a catalytic converter therein. An ECU determines that the first oxygen concentration sensor is functioning abnormally if an output from the first oxygen concentration sensor does not change when an output from the second oxygen concentration sensor changes.

Abstract: A system for detecting failure of a fuel pressure sensor in an internal combustion engine, including an injector (32) provided at an intake system of the engine downstream of a throttle valve (38), a fuel supply passage (16) connected to a fuel supply source (fuel tank 12) for supplying fuel to the injector (32), pressure regulator (28) provided in the fuel supply passage (16) and operating to maintain a difference between the fuel pressure (PF2A) and the manifold absolute pressure at a constant value, a fuel pressure sensor (PF2 sensor 54) for detecting the fuel pressure (PF2A) in the fuel supply passage (16) downstream of the pressure regulator, and a manifold absolute pressure sensor (62) for detecting the manifold absolute pressure (PBA) downstream of the throttle valve (38). In the system, an index indicative of a ratio (.DELTA.PF2A) of the fuel pressure (PF2A) fluctuation relative to the manifold absolute pressure (PBA) fluctuation is compared to reference values (#PF2L, #PF2H) which define a range.

Abstract: An air-fuel ratio control system for an internal combustion engine includes an ECU which cuts off fuel supply to the engine at deceleration thereof, measures a fuel cut-off period over which the fuel cut-off means cuts off fuel supply to the engine, and enriches the air-fuel ratio of a mixture supplied to the engine to a degree dependent upon the measured fuel cut-off period, at the restart of fuel supply to the engine immediately after termination of cutting-off of fuel supply to the engine.