Abstract: An intake air oxygen concentration sensor calibration device is provided with an oxygen concentration sensor that detects a concentration of oxygen contained in intake air, intake passageway pressure detection means, stable condition determination means that determines whether the intake passageway pressure is in a stable condition based on the amplitude of fluctuations in intake passageway pressure and a predetermined stable condition criterion value, calibration coefficient calculation means that calculates a calibration coefficient based on the intake passageway pressure and a reference output value of the oxygen concentration sensor, and calibration means that calibrates the output of the oxygen concentration sensor based on the calibration coefficient, wherein and the stable condition criterion value is set so that the smaller the intake passageway pressure detected, the smaller the value, and the greater the intake passageway pressure detected, the greater the value, and the calibration coefficient calc

Abstract: When the determination result of failure determination at a start of AI (auxiliary air injection=supply) is that there is a possibility of a closing anomaly due to freezing, a reevaluation process 1 being a reevaluation after a warm-up is performed. When the determination result of determination at an end of AI is that there is a possibility of an opening anomaly due to freezing, a reevaluation process 2 being a reevaluation after a warm-up is performed.

Abstract: A secondary air supply apparatus controls emissions from an engine through secondary combustion of combustible matters in exhaust gas accomplished by supplying air to an exhaust pipe upstream of an emission control device. A pressure behavior pattern is determined from a pressure value detected by a pressure sensor disposed between an air pump and an open-close valve, and a pressure variation value. The secondary air supply apparatus determines operational states of the air pump and the open-close valve based on variations of the pressure behavior pattern at the time of a secondary air supply control and at the time of a secondary air stop control.

Abstract: A fuel vapor handling apparatus supplies a purging air to a canister by using a purge pump and purges fuel desorbed from the canister into an intake pipe. A controller intermittently operates the purge so that the canister internal temperature recovers from a reduced level caused by the latent heat of vaporization of fuel during an operating period of the purge pump. Therefore, desorption of fuel from the canister during an operating period is facilitated. Since the actual operating time of the purge pump is reduced, the life of a motor that is a power unit of the purge pump becomes longer.

Abstract: A diagnostic apparatus for a fuel vapor purge system is provided which includes a pressure sensor that measures a pressure in a fuel tank, and which conducts leak diagnosis of a purge path based on a change in the pressure in the fuel tank and an amount of fuel vapor generated in the fuel tank. The change in the pressure is measured after sealing the purge path while providing a difference between inside pressure and outside pressure of the purge path, and the amount of fuel vapor is measured after applying an atmospheric pressure to the purge path and sealing the purge path. The diagnostic apparatus further detects a predetermined state after starting application of the atmospheric pressure to the purge path, and determines that the purge path has reached an atmospheric pressure state upon. detection of the predetermined state. The amount of fuel vapor generated in the fuel tank is measured when it is determined that the purge path has reached the atmospheric pressure state.

Abstract: Correction of a fuel injection amount in an internal combustion engine during purge of evaporative fuel is performed on the basis of an output from an intake-oxygen concentration sensor disposed in an intake passage of the internal combustion engine. If the amplitude of fluctuations in engine speed becomes equal to or greater than a predetermined value, it is determined that there is an anomaly in engine output. In addition, if an anomaly in engine output is detected during purge and if no anomaly in engine output is detected during stoppage of purge, an ECU determines that an anomaly has occurred in the intake-oxygen concentration sensor, cancels correction of the fuel injection amount based on an output from the intake-oxygen concentration sensor during purge, and corrects the fuel injection amount on the basis of outputs from exhaust-gas air-fuel ratio sensors.

Abstract: A fuel tank is divided into a fuel chamber and an air chamber by a bladder diaphragm. Under a condition that both the amount of intake air Ga and the engine revolution speed NE of an internal combustion engine are kept at constant values, a vapor concentration correction factor FGPG during a fuel injection duration TAU is calculated based on a change in the air-fuel ratio detected when gas is purged from the air chamber toward an intake passage of the engine. Based on the vapor concentration correction factor FGPG, it is determined whether there is fuel leakage from the fuel chamber to the air chamber. With this determination technique, a fluctuation in the air-fuel ratio is not caused by a situation where the engine is in a transitional state, during fuel leakage detection, so that the vapor concentration correction factor FGPG assumes a proper value corresponding to the vapor concentration in the air chamber.

Abstract: An evaporative emission control system is provided wherein a differential pressure valve includes a diaphragm that separates a back pressure chamber and a tank chamber from each other, and has a communication hole formed therethrough. The differential pressure valve is placed in an open state in which the diaphragm is spaced apart from a valve seat, or a closed state in which the diaphragm rests on the valve seat. The differential pressure valve further includes a closure member for closing the communication hole when the differential pressure valve is placed in the closed state, and the communication hole communicates with the back pressure chamber and the tank chamber when the differential pressure valve is in the open state.

Abstract: A fuel vapor purge system connects a fuel tank with a canister and collects fuel vapor generated in the fuel tank by the canister. The purge system purges the collected fuel vapor to an intake passage of an internal combustion engine through a purge passage. A change of pressure due to fuel vapor generation in the fuel tank is measured while the purge passage is sealed. The pressure in the purge passage is differentiated from the pressure outside the purge passage and the purge passage is sealed. In this state, a change of the pressure in the purge passage is measured. After measuring the amount of generated fuel vapor, a test for leakage in the purge passage is performed based on the change of pressure due to the fuel vapor generation when measuring changes of pressure in the purge passage during a predetermined period.

Abstract: An evaporative fuel leakage preventing device is designed such that an adsorbent is disposed in an intake passage so as to adsorb evaporative fuel generated in the intake passage during stoppage of the engine and prevent evaporative fuel from being discharged to the atmosphere. The device prevents evaporative fuel that has been previously adsorbed by the adsorbent, and that is desorbed from the adsorbent due to the ambient temperature while the engine is not in operation, from being emitted to the atmosphere even when the engine is not in operation.

Abstract: Fuel vapor is introduced into an intake passage of a direct fuel injection type engine by a fuel vapor purge apparatus. The intake passage is provided with an intake oxygen concentration sensor for detecting the amount of fuel vapor in intake air. An ECU corrects the amount of fuel injection from each direct fuel injection valve in accordance with the amount of fuel vapor detected, and changes the fuel injection starting timing and the fuel injection ending timing in accordance with the amount of fuel vapor.

Abstract: A fuel vapor purge system has a canister for adsorbing fuel vapor from a fuel tank, a bypass passage bypassing the canister, and a bypass valve for controlling the state of connection of the bypass passage to a purge passage. The bypass passage is provided with a venturi so that the flow passage resistance of the bypass passage is normally greater than the flow passage resistance of the canister. The amount of flow of gas from an air chamber to an intake passage changes in accordance with the flow passage resistance of the passage. In this case, the tank internal pressure in the air chamber converges to a value corresponding to the flow passage resistance of the passage between the air chamber and the intake passage. Therefore, based on the tank internal pressure occurring before and after the supply of a drive signal to the bypass valve, it is determined whether the bypass passage has a clogged abnormality and whether the bypass valve has a fixation abnormality.

Abstract: An evaporation fuel processing mechanism supplies fuel vapor in a fuel tank to a canister via a vapor passage and purges fuel in the canister to an air-intake passage of an internal combustion engine via a purge passage when the internal combustion engine is operated. This mechanism supplies fuel vapor in the fuel tank when refueling to the canister via a breather passage. The breather passage has a pressure sensitive valve that opens in response to a variation in pressure in the fuel tank during refueling. An air-fuel ratio variation limiting apparatus determines whether the pressure sensitive valve is open and limits a variation in the air-fuel ratio when the pressure sensitive valve is open.

Abstract: Fuel vapor is introduced into an intake passage of a direct fuel injection type engine by a fuel vapor purge apparatus. The intake passage is provided with an intake oxygen concentration sensor for detecting the amount of fuel vapor in intake air. An ECU corrects the amount of fuel injection from each direct fuel injection valve in accordance with the amount of fuel vapor detected, and changes the fuel injection starting timing and the fuel injection ending timing in accordance with the amount of fuel vapor.

Abstract: An intake air oxygen concentration sensor calibration device is provided with an oxygen concentration sensor that detects a concentration of oxygen contained in intake air, intake passageway pressure detection means, stable condition determination means that determines whether the intake passageway pressure is in a stable condition based on the amplitude of fluctuations in intake passageway pressure and a predetermined stable condition criterion value, calibration coefficient calculation means that calculates a calibration coefficient based on the intake passageway pressure and a reference output value of the oxygen concentration sensor, and calibration means that calibrates the output of the oxygen concentration sensor based on the calibration coefficient, wherein and the stable condition criterion value is set so that the smaller the intake passageway pressure detected, the smaller the value, and the greater the intake passageway pressure detected, the greater the value, and the calibration coefficient calc

Abstract: A diagnostic apparatus for a fuel vapor purge system is provided which includes a pressure sensor that measures a pressure in a fuel tank, and which conducts leak diagnosis of a purge path based on a change in the pressure in the fuel tank and an amount of fuel vapor generated in the fuel tank. The change in the pressure is measured after sealing the purge path while providing a difference between inside pressure and outside pressure of the purge path, and the amount of fuel vapor is measured after applying an atmospheric pressure to the purge path and sealing the purge path. The diagnostic apparatus further detects a predetermined state after starting application of the atmospheric pressure to the purge path, and determines that the purge path has reached an atmospheric pressure state upon detection of the predetermined state. The amount of fuel vapor generated in the fuel tank is measured when it is determined that the purge path has reached the atmospheric pressure state.

Abstract: An engine valve timing control device is disclosed, in which the valve overlap amount is controlled according to the fuel property, thereby keeping the drivability unchanged even when the fuel is changed. A shortage of engine output and cold hesitation are prevented at the same time when the engine temperature is low. The device is for controlling the valve operation characteristic of an internal combustion engine, and comprises a variable valve mechanism capable of changing the valve overlap amount and a control unit for controlling the operating amount of the variable valve mechanism in accordance with the engine operating conditions. The property of the fuel burnt in the engine is determined as light, intermediate or heavy.

Abstract: An ignition timing control device including a mass flow meter arranged in the intake passage. At the time engine warmup, at high load operation where the mass flow rate of the intake air is higher than the reference value, the ignition timing is made a basic ignition timing for engine warmup. As opposed to this, in medium load operation, where the mass flow rate of the intake air is lower than the reference value, the ignition timing is retarded from the basic ignition timing of engine warmup. When the atmospheric pressure falls, the reference value is lowered.

Abstract: An air assist device comprising a slit shaped air intake formed in the inner wall of an intake duct around a throttle valve. The assist air is taken in from the air intake ports. A downstream side edge portion of the opening of the slip shaped air intake port is formed into an arc shape which extends along a downstream side edge portion of the outer peripheral end face of the throttle valve when the throttle valve is positioned at an idling position.

Abstract: A method or an apparatus controls a continuously variable valve timing mechanism of an internal combustion engine to continuously and variably control the timing of an intake valve according to atmospheric pressure. The method or apparatus reads an engine revolution speed NE, an engine load GN, and an atmospheric pressure PA, refers to a map according to the atmospheric pressure PA, to find an atmospheric pressure correction coefficient Kpa, which is 1.0 at low altitudes with PA=760 mmHg and decreases as the altitude increases, i.e., as the atmospheric pressure PA decreases, calculates a corrected engine load GNpa as GNpa.rarw.GN/Kpa, and refers to a map according to the corrected engine load GNpa and engine revolution speed NE, to find a target displacement to be imposed on the open/close timing of the intake valve.