Abstract: In a fuel injection system for an internal combustion engine, engine cylinders are divided into a plurality of cylinder groups. An air passage is provided for supplying mixing air to areas near injection holes of fuel injection valves so as to facilitate atomization of fuel injected from the respective fuel injection valves. The air passage is opened synchronously with a fuel injection of each fuel injection valve such that the mixing air is selectively distributed to the above-noted areas per cylinder group. The mixing air is distributed for such a cylinder group that includes the engine cylinder being injected with the fuel from the corresponding fuel injection valve. The air passage includes a branch portion for the distribution of the mixing air to the above-noted areas. Capacities of the air passage from the branch portion to the respective fuel injection valves may be set substantially equal to each other so as to further facilitate the atomization of the injected fuel.

Abstract: An oxygen concentration measuring device capable of significantly shortening the period of time during which oxygen concentration cannot be measured. When measuring the temperature of a sensor main body, a microcomputer determines the temperature of the sensor main body by estimating a saturation current starting from a current detected by a current detecting circuit in a period of time before current flowing through the sensor main body finishes rising, after the sensor main body has been negatively biased by a bias control circuit. The sensor main body is positively biased by the bias control circuit directly after the period of time has lapsed. The microcomputer determines an air fuel ratio by using current in a period of time before current flowing through the sensor main body due to the positive bias finishes decreasing.

Abstract: The present invention pertains to a method for producing a mixture including an injected engine fuel from an injector, a combustion engine intake-air and an evaporative gas from the engine fuel. The method includes the steps of measuring a characteristic of the evaporative gas and changing step for changing a mixing ratio of the evaporative gas to at least one of the injected engine fuel and the combustion engine intake-air, according to the measured characteristic of the evaporative gas, by changing a flow rate of the combustion engine intake-air.

Abstract: A fuel injection system for a multi-cylinder internal combustion engine is provided. This fuel injection system includes a plurality of fuel injection valves each arranged to inject fuel into an intake port of each cylinder of the engine, an air passage connected to a portion of an air intake passage leading to the intake ports, a plurality of branch air passages each communicating with a preselected portion around an injection nozzle of each fuel injection valve, an air control valve, connecting between the air passage and the plurality of branch air passages, for selectively introducing a portion of intake air in the air intake passage to the preselected portions around the injection nozzles of the fuel injection valves.

Abstract: A fuel vapor purging control system for an internal combustion engine is provided. This purging control system incorporates an air/fuel ratio compensating system which includes a purge control valve for controlling a purge flow rate of an air-fuel vapor mixture flowing into an induction system of the engine through a purge passage according to a preselected engine operating condition parameter, a sensor disposed in the purge passage for determining an amount of fuel in the air-fuel vapor mixture, an air/fuel ratio controller for modifying an amount of fuel in an air/fuel mixture injected through a fuel injection system of the engine based on the amount of fuel in the air-fuel vapor mixture determined by the sensor for assuring a desired air/fuel ratio of the air/fuel mixture entering a combustion chamber of the engine.

Abstract: An engine temperature is measured an opening of a door is detected so an electrical conduction is made to a heater for heating a sensor element by setting a target element temperature to a relatively high level if such engine temperature (cooling water temperature Thw) is relatively low or, on the other hand, by setting the target element temperature to a relatively low level if the cooling water temperature is relatively high. Then the element temperature is detected and the heater is turned off when the element temperature has reached the target temperature.

Abstract: A spark timing control system includes an engine state detecting device for detecting a state of an internal combustion engine. A vehicle vibration detecting device serves to detect a vibration of a vehicle in a longitudinal direction with respect to the vehicle. A target vehicle vibration value calculating device serves to calculate a target vehicle vibration value on the basis of one of results of detections by the engine state detecting device and the vehicle vibration detecting device. A control quantity setting device serves to set a control quantity of a spark timing so as to control the result of detection by the vehicle vibration detecting device at the target vehicle vibration value by use of an optimal feedback gain which is determined according to a dynamic model of the engine.

Abstract: The digital control unit of the present invention relates to improvements in what is called recent control, and more particularly relates to the idle rotating speed control unit of an internal combustion engine in which the idle rotating speed can be quickly converged to the target rotating speed in the case where a load given from the outside varies. Especially, when the value of the state variable is reversely calculated from the state in which open loop control is conducted, the initial value can be accurately determined.

Abstract: There is disclosed a self-diagnosis apparatus in which when detecting a supply abnormally (i.e., failure to lead fuel evaporation gas into an intake passage), the abnormality can be accurately detected, taking into consideration variations in the fuel gas density (variations in the ambient temperature, variations in the volatility of the fuel, and etc.) due to the residual air in a fuel tank. In the apparatus, the amount of flow of the gas from the fuel tank to a canister can be detected, and a control circuit controls a purge valve to close a fuel gas discharge passage, and in this condition the control circuit detects the amount of flow of the gas from the fuel tank to the canister. When this flow amount exceeds a set value, the control circuit controls the purge valve to close and open the discharge passage, and judges in accordance with a change in an air-fuel ratio detected at this time by an O.sub.2 sensor whether or not any abnormality exists.

Abstract: A fuel evaporative emission flow rate detecting system is capable of detecting a small flow rate of the fuel evaporative emission. The system includes an electromagnetic valve (22) in a communication passage (21). The pressure of the fuel evaporative emission in the fuel tank is detected by means of a magnetic flux detector or so forth. A control circuit is responsive to the pressure of the fuel evaporative emission reaching 15 mmHg, for example, while the communication passage (21) is held closed, to open the communication passage (21). On the other hand, the control circuit closes the communication passage when the pressure of the fuel evaporative emission becomes lower than or equal to 8 mmHg. Depending on a period, in which the communication passage (21) is held open, the flow rate of the fuel evaporative emission is calculated.

Abstract: Disclosed is a self-diagnosis apparatus in a fuel evaporation gas scattering preventing system in an internal combustion engine.

Abstract: An internal combustion engine in which a purge control valve is provided in a fuel vapor supply passage connecting a canister and an intake pipe of the internal combustion engine, the opening degree of the purge control valve is regulated by a purge flow rate control unit depending on operating condition of the internal combustion engine, and the opening degree of a rotational speed control valve is regulated to adjust an amount of intake air into the internal combustion engine, thereby changing a rotational speed of the internal combustion engine.

Abstract: An engine control apparatus comprises: an actual control condition detector for detecting an actual control condition of an engine; an adjusting device for adjusting the actual control condition of the engine; and a controller for controlling the adjusting device such that the actual control condition of the engine is controlled to a target control condition using a state variable amount and a feedback constant determined on the basis of a dynamic model of the engine, wherein the controller has: a predicated control condition operation circuit for operating a predicted control condition on the basis of the dynamic model of the engine; a deviation operation circuit for operating a deviation of the predicated control condition from the target control condition; a changing circuit for changing control of the controller such that fluctuations of the control condition become small in accordance with a judgement made such that an error of the dynamic model exceeds a tolerance when the deviation exceeds a predetermi

Abstract: In an engine control system which determines the amount of fuel to be injected on the basis of an intake pipe pressure detected downstream of a throttle valve and engine speed (D-EFI), fail-safe action is provided when a failure of an intake pipe on the downstream side of the throttle valve is detected. The fail-safe apparatus of the present invention is designed to signal the occurrence of an abnormality with the intake system when the throttle valve is not being opened, that is, the throttle valve is stationary or is closing, a vehicle speed variation exceeds its specific value and the engine speed exceeds its specific value. When these conditions are detected, engine power is controlled lower, thereby assuring vehicle driving safety.

Abstract: In fuel injection system of an internal combustion engine of a vehicle, a fuel injection valve is activated to inject pre-start fuel in response to turn-on of a main switch by a vehicle driver. A starter motor is not activated until a predetermined delay period (T.sub.D) elapses after the turn-on of the main switch. During the delay period (T.sub.D) the injected fuel is vaporized. After the delay period (T.sub.D) the vaporized fuel is taken into engine cylinders when the engine is cranked by the starter motor so that fuel is ignited in the engine easily.

Abstract: In a fuel injection control system for an internal combustion engine, a basic fuel amount is determined in accordance with detected values of intake air pressure and rotational speed of the engine. The detected value of the intake air pressure is averaged by a predetermined averaging function to infer temperature of air flowing into a cylinder of the engine. The basic fuel amount is corrected by the inferred temperature, more specifically, by the difference between the detected value of the intake air pressure and the averaged value of the same so that undesired change in air-fuel ratio resulting from comparatively slow change in temperature of air flowing into engine cylinder upon acceleration and deceleration of the engine is compensated for.

Abstract: In apparatus for injecting fuel into an internal combustion engine, a flip-flop used for frequency dividing an engine rotational angle signal is arranged to be reset when a basic injection pulse is not coincident with a cylinder-determining pulse signal. The basic injection pulse is produced by a Q/N charge-discharge circuit arranged to start charging a capacitor in response to a leading edge of an output pulse from the flip-flop and to start discharging the same in response to a trailing edge of the same where time constant on charging is constant and time constant on discharging is variable depending on the quantity Q of intake air of the engine. The basic injection pulse is used to produce final injection pulse with which fuel injection valves are operated where the width of the basic injection pulse determines the basic amount of fuel to be injected. After the flip-flop is reset, its output pulse is shifted by 180.degree.

Abstract: An electronically controlled fuel injection system for an internal combustion engine, the system being of the type which controls fuel injection using the charging and discharging of a capacitor and comprising engine operating parameter sensors, a capacitor, and a control unit for controlling the charging and discharging of the capacitor. The charging of the capacitor is initiated at a timing determined as a function of engine speed and throttle opening angle and the discharging thereof is initiated subsequently to the completion of the charging. The charging time period is determined by engine speed and the discharging current is determined by intake air quantity. A basic fuel injection signal is produced so as to have a pulse duration equal to the discharging time period.

Abstract: In a fuel injection control system for an internal combustion engine, operating conditions of the engine are constantly monitored. A transient condition of the engine is detected from the monitored operating conditions. A fuel injection quantity is derived from the monitored operating conditions to effect injection at first intervals during the absence of the transient condition and at second intervals during the presence of the transient condition. Fuel injectors are activated in response to the derived fuel injection quantity.

Abstract: In an electronic fuel injection control system for an internal combustion engine, a first integration circuit is responsive to an angular signal with a time period in inverse proportion to the rotational speed of the engine for integrating the first half of the time period of the angular signal and for producing a first integration signal indicative of a resultant value of the integration, a hold circuit is arranged to hold the value of the first integration signal upon lapse of the first half of the time period and to produce a hold signal of the held value and maintain it for the second half of the time period and the first half of the time period of the following angular signal, a second integration circuit is responsive to the angular signal for integrating the value of an air quantity signal indicative of the quantity of air drawn into the engine at each start of the first and second halves of the time period and for producing a second integration signal indicative of a resultant value of the integration