Abstract: A first catalyst 21 which stores or releases oxygen according to an air-fuel ratio, and a second catalyst 22 which traps or releases NOx according to the air-fuel ratio, are provided in an exhaust passage 9 of an engine 1. A controller 6 temporarily shifts the air-fuel ratio of the engine 1 to rich when it is determined that the NOx trap catalyst second catalyst 22 is released. At this time, the controller 6 increases a reducing agent supply amount due to the rich shift to be larger, the larger the oxygen amount stored by the two catalysts 21, 22. In this way, the air-fuel ratio in the second catalyst 22 is maintained at a target stoichiometric or rich air-fuel ratio.

Abstract: A stream of pulses related to rotation rate drives an interrupt to store first timer values of a first timer and to set a second timer to run from zero. At predetermined fixed time intervals, second timer values of the second timer are stored. The stored first timer values are sampled to determine a first rate related to the input stream. The stored second timer values are sampled to determine a second rate. The first and second rates are selectively used as a final rotation rate related to the input stream.

Abstract: A cylinder intake air mass quantity for an engine is calculated in accordance with the cylinder intake air volume quantity, the manifold air mass quantity and a manifold volume. The cylinder intake air volume quantity is calculated in accordance with a cylinder volume at an intake valve closing timing. The manifold air mass quantity is calculated from a balance between an intake manifold inflow air mass quantity and an intake manifold outflow air mass quantity. The manifold inflow air mass quantity Qa·&Dgr;t is reset to a minimum setting value when an engine stop state with no intake air induction is detected.

Abstract: A camshaft rotational phase detecting apparatus for an engine provided with a variable valve timing control mechanism which controls a camshaft rotational phase of an engine valve to a target camshaft rotational phase by varying a rotational phase of a camshaft relative to a crankshaft. The camshaft rotational phase detecting apparatus is configured to detect a camshaft rotational phase as a detected camshaft rotational phase based on a signal from a sensor. In the apparatus, the detected camshaft rotational phase is substituted with a maintained rotational phase for a predetermined period and is substituted with a target camshaft rotational phase after a lapse of the predetermined period, when the camshaft rotational phase is not detected. In the apparatus, the maintained rotational phase is set corresponding to the detected camshaft rotational phase detected before a timing that the camshaft rotational phase is not detected.

Abstract: A stream of pulses related to rotation rate drives an interrupt to store first timer values of a first timer and to set a second timer to run from zero. At predetermined fixed time intervals, second timer values of the second timer are stored. The stored first timer values are sampled to determine a first rate related to the input stream. The stored second timer values are sampled to determine a second rate. The first and second rates are selectively used as a final rotation rate related to the input stream.

Abstract: In fuel injection control apparatus and method for an engine having a variably operated engine valve in which at least a closure timing of an intake valve is variably controlled, a controller determines whether an actual closure timing of the intake valve is in a steady state, calculates a volume of a cylinder calculated from a target control value of the closure timing of the intake valve when determining that the actual closure timing is in the steady state and a fresh-air rate within the cylinder, calculates a mass air quantity sucked into the cylinder on the basis of a mass air quantity within an intake manifold calculated by income and outgo calculations of inflow and outflow quantities of a mass air within the intake manifold and a volume of the manifold, and calculates a fuel injection quantity on the basis of the mass air quantity sucked into the cylinder.

Abstract: A camshaft rotational phase detecting apparatus for an engine provided with a variable valve timing control mechanism which controls a camshaft rotational phase of an engine valve to a target camshaft rotational phase by varying a rotational phase of a camshaft relative to a crankshaft. The camshaft rotational phase detecting apparatus is configured to detect a camshaft rotational phase as a detected camshaft rotational phase based on a signal from a sensor. In the apparatus, the detected camshaft rotational phase is substituted with a maintained rotational phase for a predetermined period and is substituted with a target camshaft rotational phase after a lapse of the predetermined period, when the camshaft rotational phase is not detected. In the apparatus, the maintained rotational phase is set corresponding to the detected camshaft rotational phase detected before a timing that the camshaft rotational phase is not detected.

Abstract: A cylinder intake air mass quantity for an engine is calculated in accordance with the cylinder intake air volume quantity, the manifold air mass quantity and a manifold volume. The cylinder intake air volume quantity is calculated in accordance with a cylinder volume at an intake valve closing timing. The manifold air mass quantity is calculated from a balance between an intake manifold inflow air mass quantity and an intake manifold outflow air mass quantity. The manifold inflow air mass quantity Qa·&Dgr;t is reset to a minimum setting value when an engine stop state with no intake air induction is detected.

Abstract: In fuel injection control apparatus and method for an engine having a variably operated engine valve in which at least a closure timing of an intake valve is variably controlled, a controller determines whether an actual closure timing of the intake valve is in a steady state, calculates a volume of a cylinder calculated from a target control value of the closure timing of the intake valve when determining that the actual closure timing is in the steady state and a fresh-air rate within the cylinder, calculates a mass air quantity sucked into the cylinder on the basis of a mass air quantity within an intake manifold calculated by income and outgo calculations of inflow and outflow quantities of a mass air within the intake manifold and a volume of the manifold, and calculates a fuel injection quantity on the basis of the mass air quantity sucked into the cylinder.

Abstract: A first catalyst 21 which stores or releases oxygen according to an air-fuel ratio, and a second catalyst 22 which traps or releases NOx according to the air-fuel ratio, are provided in an exhaust passage 9 of an engine 1. A controller 6 temporarily shifts the air-fuel ratio of the engine 1 to rich when it is determined that the NOx trap catalyst second catalyst 22 is released. At this time, the controller 6 increases a reducing agent supply amount due to the rich shift to be larger, the larger the oxygen amount stored by the two catalysts 21, 22. In this way, the air-fuel ratio in the second catalyst 22 is maintained at a target stoichiometric or rich air-fuel ratio.

Abstract: An intake air quantity calculating apparatus for an internal combustion engine equipped with a variable valve timing control mechanism is provided. By the apparatus, an intake pipe pressure is detected or estimated. An intake air pulsation rate is determined on the basis of the detected or estimated intake pipe pressure and engine speed. An air flow error correction term basic value is determined on the basis of a throttle valve opening degree and engine speed. The air flow error correction term basic value is corrected on the basis of the intake air pulsation rate, whereby to determine an air flow error correction term for correcting an error in detection of an intake air quantity by an air flow meter. By the air flow error correction term, an intake air quantity detected by an air flow meter is corrected, whereby it becomes possible to improve the accuracy in calculation of the intake air quantity.

Abstract: In apparatus and method for calculating an internal cylinder intake-air quantity for a variable valve timing controlled engine, an air quantity flowing into the intake manifold from an output of an airflow meter is calculated, the airflow meter being installed in an upstream portion of an intake manifold with respect to an intake valve whose at lease closure timing is variably controlled, a cylinder volume of a corresponding cylinder of the engine is calculated, an income and outgo of an air quantity flowing into the intake manifold and a cylinder intake-air quantity flowing from the intake manifold into the corresponding cylinder is calculated to derive an air quantity in the intake manifold, the internal cylinder intake-air quantity is calculated on the basis of the air quantity of the intake manifold and the cylinder volume, and the calculated cylinder volume is corrected on the basis of at least valve closure timing of the intake valve.

Abstract: In a water-cooled engine comprising a catalyst for purifying exhaust in an exhaust pipe, a catalyst is rendered active at an early stage by arranging an air-fuel ratio of a fuel mixture supplied to the engine to be lean on startup. A catalyst activation water temperature corresponding to full activation of this catalyst is set, and the air-fuel ratio is arranged to be leaner than a theoretical air-fuel ratio during a period from engine startup to when a cooling water temperature reaches the catalyst activation water temperature. After the cooling water temperature reaches the catalyst activation water temperature, the air-fuel ratio is shifted to the stoichiometric air-fuel ratio. In this way, lean control is optimized to activate the catalyst.

Abstract: A learning value of a multiplication term for correcting a basic injection amount and a learning value of an addition term for correcting the basic injection amount are stored in a memory. The learning value of the addition term is converted to a proportion relative to the basic injection amount, and these learning values are modified such that the sum of the proportion and the multiplication term lies within a predetermined range. The proportion of the total learning values relative to the basic injection amount is thereby suppressed to a constant level so that the effect of incorrect learning on air-fuel ratio control is also suppressed.

Abstract: In a vehicle engine, when an accelerator pedal is released and a vehicle speed has decreased after fuel injection by a fuel injector has stopped, a controller restarts fuel injection. An engine rotation speed decrease rate immediately prior to restarting fuel injection is calculated, and a restart fuel injection amount is set which is larger the larger the decrease rate. In this way, the torque generated by the engine quickly recovers even during rapid deceleration, while during gradual deceleration, the generated torque increases gradually so that a torque shock does not occur.

Abstract: A target torque is calculated as a proportion PI relative to a torque generated by an engine at a basic ignition timing. An ignition timing correction amount is calculated based on this proportion PI, and by correcting the ignition timing by this correction amount, an ignition timing correction which precisely matches a torque-down request is performed rapidly and accurately.

Abstract: A fuel injection amount in an engine is determined based on a cylinder air volume equivalent fuel injection amount and a wall flow correction amount. The fuel injection amount is also decreased in an initial injection when fuel injection is restarted after it is has been stopped. In this way, sudden torque increases are suppressed without causing a loss of engine rotation speed when fuel injection is restarted after it has been stopped.

Abstract: An apparatus for use with an internal combustion engine having a fuel vapor trap from which fuel vapor is purged into the engine through a purge passage having a purge control valve provided therein. The purge control valve is controlled to permit fuel vapor purge through the purge passage based on the existing engine operating conditions. An air/fuel ratio feedback control correction factor is calculated to correct the air/fuel ratio within a predetermined range based on the air/fuel ratio of the mixture supplied to the engine. A gain value is calculated based on a deviation between the air/fuel ratio feedback correction factor calculated with the fuel vapor purge and the air/fuel ratio feedback correction factor calculated without the fuel vapor purge and a purge rate of the fuel vapor flow rate to the intake air flow rate. The calculated gain values are stored in a memory in respective memory locations addressable by different fuel vapor amounts.

Abstract: In a multicylinder internal combustion engine having fuel injection valves for respective cylinders, an improved fuel injection control system includes a first device for detecting the amount of air fed to each cylinder and a second device for calculating a basic fuel injection amount at given intervals on the basis of the detected quantity of state, for weighting the basic fuel injection amount at the given intervals to obtain a substantial fuel injection amount which corresponds to the amount of air fed to the cylinder, and for correcting the substantial fuel injection amount on the basis of a given rate of a variation between the basic fuel injection amount and the substantial fuel injection amount thereby to obtain a final fuel injection amount. The control system also includes a third device for driving each of the injection valves on the basis of the final fuel injection amount.

Abstract: A pitch-based carbon or graphite fiber having a leafy lamella arrangement in at least 30% of the fiber cross-sectional area and having a tensile strength of at least 300 kg/mm.sup.2. The fiber is prepared by melt-spinning an optically anisotropic pitch having an optically anisotropic phase content of at least 50% through a spinneret in which at least one central line distance in a spinning hole simultaneously satisfies the following requirements I and II,Ln<10 I1.5.ltoreq.Ln/Wn.ltoreq.20 IIwherein Ln stands for central line distances in mm in the spinning hole and Wn stands for wetted perimeter widths in mm in the spinning hole, and infusibilizing and carbonizing the formed pitch fiber.