Abstract: In an engine exhaust system, an NOx catalyst for occluding NOx in a state of the lean air-fuel ratio and reducing the occluded NOx in the state of the rich air-fuel ration A CPU sets a target air-fuel ratio of a mixture supplied to an engine to the lean side with respect to the stoichiometric air-fuel ratio for the lean mixture combustion. The CPU sets a rich time for a rich mixture combustion in accordance with the engine operating state and the NOx purification rate in the NOx catalyst. In this moment, the shortest rich time is set within a range in which a desired NOx purification rate by the NOx catalyst is obtained. A three-way catalyst may be arranged upstream of the NOx catalyst. The three-way catalyst carries only a noble metal such as platinum having no oxygen storing capability.

Abstract: A residual fuel quantity measuring device for automobiles has a fuel flow rate sensor provided in a filler neck of a fuel tank for measuring the flow rate of liquid fuel supplied to a fuel tank. A computer computes the quantity of liquid fuel remaining in the fuel tank from a previously stored residual quantity of liquid fuel, the measured fuel flow rate, the injection rate of fuel from fuel injection valves, and the purge quantity of fuel evaporated in the fuel tank. A fuel meter visually displays the thus computed residual quantity of liquid fuel in the fuel tank.

Abstract: A fuel transfer model of a fuel supply system is used to set and control the fuel pump of a return less fuel injection system. The model simulates characteristics of the fuel pump, fuel pressure transfer delay of fuel supply conduits and fuel pressure variation characteristics such as caused by expansion and compression of the fuel supply conduit volume due to an elastic coefficient and the like. The fuel pump model simulates a torque applied to the fuel pump motor, inertia, and the relationships between pump rotational speed, fuel pressure and fuel pump discharge amounts. A compensation control arithmetic calculation model may be derived from inverse calculation based on this fuel transfer model.

Abstract: A leakage diagnosing apparatus for an evaporated gas purge system, which executes purge system leakage diagnosis based on a detected pressure change amount and an introduced pressure which is introduced into a part of the purge system including at least a fuel tank and a canister. The detected pressure change amount is obtained by detecting pressure in the part of the purge system after such part of the purge system is hermetically sealed. Accordingly, the reliability of the leakage diagnosis is improved because an erroneous diagnosis caused by the introduced pressure is prevented. The detected pressure change amount may be compensated based on the introduced pressure into the sealed gas purge system. Accordingly, an erroneous leakage determination is prevented, and the reliability of leakage determination is improved.

Abstract: In an engine exhaust system, an NOx catalyst for occluding NOx in a state of the lean air-fuel ratio and reducing the occluded NOx in the state of the rich air-fuel ratio. A CPU sets a target air-fuel ratio of a mixture supplied to an engine to the lean side with respect to the stoichiometric air-fuel ratio for the lean mixture combustion. The CPU sets a rich time for a rich mixture combustion in accordance with the engine operating state and the NOx purification rate in the NOx catalyst. In this moment, the shortest rich time is set within a range in which a desired NOx purification rate by the NOx catalyst is obtained. A three-way catalyst may be arranged upstream of the NOx catalyst. The three-way catalyst carries only a noble metal such as platinum having no oxygen storing capability.

Abstract: An antidissipation apparatus for evaporated fuel vapor for an internal combustion engine. A purge passage connects the intake manifold and the fuel tank. A canister is installed in the purge passage and adsorbs evaporated fuel vapor generated in the fuel tank. A purge pump is installed in the purge passage and delivers the adsorbed evaporated fuel vapor to the intake manifold. Since the purge pump is driven by at least a part of a fuel flow in the fuel passage, the purge pump can change its discharge amount of the adsorbed evaporated fuel vapor to the intake manifold according to an amount of the fuel flow in the fuel passage. Therefore, the evaporated fuel vapor which is adsorbed at the canister can be supplied (purged) to the intake manifold by the purge pump forcibly even if the engine is a lean-burn type which can not employ large negative pressure of the intake manifold.

Abstract: Intake pressure is estimated for an engine load using an averaged accelerator depression position derived by smoothing sensed changes in accelerator depression position. Throttle valve opening angle is controlled based on the thus estimated intake pressure. A corresponding fuel injection value is calculated and supplied to the engine thus matching the estimated air and fuel amounts. Thus, deviation of the air-fuel mixture from a stoichiometric ratio can be reduced even with rapid and complicated accelerator operations.

Abstract: An inflow quantity of an exhaust gas component flowing into a catalyst is calculated based upon air fuel ratio detected by an upstream air fuel ratio sensor which is provided on the upstream side of the catalyst. In addition, an outflow quantity of an exhaust gas component flowing out of the catalyst is calculated based upon air fuel ratio detected by a downstream air fuel ratio sensor which is provided on the downstream side of the catalyst. The quantity of an exhaust gas component absorbed by the catalyst can be detected in real time based upon a difference between the inflow quantity and outflow quantity. Thus, a state of the catalyst can be precisely detected in real time.

Abstract: In an engine exhaust catalyst warm-up control, ignition timing is delayed from normal first to raise the catalyst temperature, and then a fuel injection amount is dithered to increase and decrease alternately from a normal amount until the catalyst temperature reaches the catalyst activation completion temperature. In place of the ignition delay control, afterburning control may be employed in which fuel cut for a cylinder and fuel increase for the other cylinders are executed. Further, the catalyst warm-up control may be performed by controlling a supercharging operation and an exhaust gas recirculation operation cooperatively.

Abstract: In a fuel supply system employing a returnless fuel pipe arrangement, a relief valve is provided at a discharge side of a fuel pump. The relief valve is opened when fuel pressure in the fuel pipe arrangement becomes no less than a system protective pressure, so as to relieve the fuel pressure to protect the system. The relief valve is also arranged to be open when the fuel pressure in the fuel pipe arrangement becomes higher than a target fuel pressure by a predetermined value or when the fuel cut is performed. Thus, the fuel pressure in the fuel pipe arrangement is lowered. Thereafter, when the fuel pressure in the fuel pipe arrangement is lowered to a pressure near the target fuel pressure, the relief valve is arranged to be closed so that the fuel pressure in the fuel pipe arrangement is held substantially at the target fuel pressure.

Abstract: An air-fuel ratio control apparatus for an internal combustion engine is provided which includes an air-fuel ratio determining circuit which determines an air-fuel ratio of exhaust gases flowing upstream of a catalytic converter for controlling the air-fuel ratio of the exhaust gases so as to agree with a target air-fuel ratio under feedback control, a sorbed substance amount determining circuit for determining the amount of substances sorbed in the catalytic converter, and a target air-fuel ratio determining circuit for determining said target air-fuel ratio so that the amount of substances determined by said sorbed substance amount determining means falls within a given range.

Abstract: An abnormality detecting apparatus for use in a fuel-transpiration preventing mechanism can eliminate effects of changes in operating conditions and variations in equipment to increase the accuracy of abnormality detection. Fuel gas generated in a fuel tank and then absorbed by an absorbing material accommodated in a canister is discharged to an intake pipe by opening and closing a purge control valve. A change in pressure at a negative-pressure holding time after introduction of a negative pressure to the fuel-transpiration preventing mechanism and a change in pressure at an atmosphere-air introduction time after the negative-pressure holding time are calculated and the changes in pressure are used as a basis for determining the existence of an abnormality. As a result, effects of changes in operating conditions and effects of variations in purge control valves and canister closing valves can be eliminated, thus allowing the detection accuracy to be improved.

Abstract: In a heater control of an oxygen sensor, a heater control circuit is rendered fully conductive at 100% duty initially to supply full power to a heater until the resistance value of the heater reaches a predetermined initial value corresponding to a predetermined temperature. Then, the duty of the heater control circuit is feedback controlled so that the heater temperature becomes a target value until the internal resistance of the oxygen sensor reaches a target temperature, and further, after the internal resistance of the oxygen sensor S reaches the target temperature, the duty of the heater control circuit is feedback controlled so that the element temperature of the sensor becomes a target value.

Abstract: In an apparatus for detecting a saturation gas amount absorbed by a catalytic converter disposed in an exhaust system of an engine, an air-to-fuel ratio detecting device is disposed in a region of the engine exhaust system downstream of the catalytic converter for monitoring exhaust gas, which has passed through the catalytic converter, to detect an air-to-fuel ratio of an air-fuel mixture causing the exhaust gas. An air-to-fuel ratio changing device serves to change an air-to-fuel ratio of an air-fuel mixture fed to the engine by a correction quantity in a given direction, and serves to maintain changing the air-to-fuel ratio during a correction time.

Abstract: To shorten the time during which oxygen concentration cannot be detected, the temperature of an oxygen concentration sensor is detected by negatively biasing the sensor using a bias control circuit. A microcomputer estimates a saturated current thereof at one time before the current flowing through the sensor section ends rising based on a current detected by a current detecting circuit at that time. Further, the sensor is positively biased right after the elapse of a negative bias voltage application period by the bias control circuit. The microcomputer determines the air-fuel ratio based on the current flowing through the sensor at that time. The period in which the negative bias is applied is variably set appropriately by the microcomputer in response to changes of engine temperature and intake air amount. Furthermore, to activate the sensor quickly, the temperature of the sensor section is detected and a heater is controlled based thereon.

Abstract: A vibration damping control system for an automotive vehicle is provided. This system includes a torque generator operating with given operation timing to produce a torque vibration of a preselected frequency and an operation timing controller. The operation timing controller initially determines a phase difference between engine revolution and frequency of vehicle vibration formed of a resultant vector defined by a first vibration component caused by movement of a crankshaft of the engine and a second vibration component caused by movement of a piston of the engine. The controller then modifies the operation timing of the torque generator to provide the torque vibration in an opposite phase relative to the vehicle vibration based on the phase difference determined to compensate the vehicle vibration.

Abstract: In an air-fuel ratio control system for an internal combustion engine, a target air-fuel ratio is set on a side opposite to a direction of deviation of a monitored upstream side air-fuel ratio in such a manner as to counterbalance or offset the deviation of the upstream side air-fuel ratio. The deviation of the upstream side air-fuel ratio may be derived in the form of an mount of a particular component adsorbed in a catalytic converter. A learned value may be used to correct the monitored upstream side air-fuel ratio. Further, a monitored downstream side air-fuel ratio may be used to monitor the setting of the target air-fuel ratio.

Abstract: An air-fuel ratio control system for an internal combustion engine includes two air-fuel ratio sensors, one upstream of a catalytic converter and the other downstream of the catalytic converter. When an output of the downstream air-fuel ratio sensor has been inverted between rich and lean, a target air-fuel ratio is corrected by a skip amount in a direction opposite to that of the inversion. On the other hand, at no inversion, the target air-fuel ratio is corrected by an integral amount in a direction opposite to deviation of the output of the downstream air-fuel ratio sensor. A fuel injection amount is derived based on a differential between the target air-fuel ratio and an output of the upstream air-fuel ratio sensor. An engine operating condition, the output of the downstream air-fuel ratio sensor or a deterioration degree of the catalytic converter may be used to change the skip amount and the integral amount.

Abstract: An assist air control system for an internal combustion engine introduces, via an assist air passage bypassing a throttle valve, a portion of intake air flowing in an intake pipe upstream of the throttle valve to an area where fuel is injected from a fuel injection valve, so as to facilitate atomization of the injected fuel. The assist air passage includes a flow control unit for opening and closing the assist air passage. The degree of opening of the assist air passage is limited to a value that is reduced as an engine temperature increases, while increased as an engine load increases. The opening degree of the flow control unit may be controlled electrically, mechanically, or both. In this case, the electrically controlled opening degree value is set smaller than the mechanically controlled opening degree value.

Abstract: A starting system and a method for starting an automotive internal combustion engine, the method and apparatus being capable of improving the starting ability of the engine. The starting system includes a starter motor, a means for measuring a crankshaft angle of the engine, and a control means which controls the entire system. The system is initiated by a start command being input thereto. The system, i.e., the control means, then preliminarily drives the starter motor in a reverse direction in a predetermined relation to the start command so that a load torque on the starter motor is reduced. Then, the control means of the system determines whether the reverse rotation of the starter motor has attained a predetermined value. Then, the starter motor is driven in a forward direction when the reverse rotation has attained the predetermined value.