Abstract: When control to maintain a constant engine rotation number is executed, the electronic control unit constantly monitors an error of detected throttle position data with respect to a desired throttle control value, executes a first stage of a failure judgment method to judge that a failure of a throttle control system has occurred in a case where an absolute value of the error exceeds a predetermined threshold value continuously for a predetermined time or longer, and executes a second stage of the failure judgment method to judge that a serious failure has occurred in the system in a case where a detected engine rotation number exceeds a predetermined rotation number continuously for a predetermined time or longer, to perform predetermined operations in accordance with the judgment results.

Abstract: An air-fuel ratio control device comprising a fuel supply unit, engine operation state detector, air-fuel ratio information detector, and an electronic control unit is disclosed. The electronic control unit determines a fuel injection amount which realizes a target air-fuel ratio while using engine load information by the engine operation state detector on the basis of air-fuel ratio information by the air-fuel ratio information detector, and then outputs a driving signal to the fuel supply unit, to execute feedback control mainly at an excessively rich side air-fuel ratio, characterized in that the air-fuel ratio information detector is an exhaust gas temperature sensor.

Abstract: When control to maintain a constant engine rotation number is executed, the electronic control unit constantly monitors an error of detected throttle position data with respect to a desired throttle control value, executes a first stage of a failure judgment method to judge that a failure of a throttle control system has occurred in a case where an absolute value of the error exceeds a predetermined threshold value continuously for a predetermined time or longer, and executes a second stage of the failure judgment method to judge that a serious failure has occurred in the system in a case where a detected engine rotation number exceeds a predetermined rotation number continuously for a predetermined time or longer, to perform predetermined operations in accordance with the judgment results.

Abstract: There is provided an air-fuel ratio control device comprising: fuel supply means; engine operation state detection means; air-fuel ratio information detection means; and an electronic control unit, the electronic control unit being configured to determine a fuel injection amount which realizes a target air-fuel ratio while using engine load information by the engine operation state detection means on the basis of air-fuel ratio information by the air-fuel ratio information detection means, and then output a driving signal to the fuel supply means, to execute feedback control mainly at an excessively rich side air-fuel ratio, characterized in that the air-fuel ratio information detection means is an exhaust gas temperature sensor, and while estimating an air-fuel ratio at this time on the basis of detected exhaust gas temperature information by a predetermined obtaining method, the air-fuel ratio is used for the control.

Abstract: In a fuel injection control method of an engine which an intake air flow rate is estimated by a predetermined calculating method, using data on detected intake pipe pressure and engine rotating speed, a fuel injection time is determined by a predetermined calculating method, using the intake air flow rate, and a deviation from a target engine rotating speed, and an injector driving signal is outputted by a fuel injection control device, the fuel injection time is obtained by adding a battery voltage fluctuation correction time, and a transient correction injection time which corrects a deviation from the target engine rotating speed, which is obtained by a predetermined calculating method, to a basic injection time obtained by a predetermined calculating method.

Abstract: An engine revolution number is controlled by operating opening and closing of a throttle valve by an engine revolution number control means on the basis of a deviation between a detected engine revolution number and a target engine revolution number, and air-fuel ratio control means applies the engine revolution number and the intake air flow rate to a predetermined numerical formula which is derived from a plurality of sets of data groups including the intake air flow rate and air-fuel ratio, which are obtained from a predetermined experiment model, and expresses the relationship between each data, to thereby calculate a fuel injection time for realizing a target air fuel ratio. A target air fuel ratio is thus realized while minimizing any delay of a response even during a transient operation, and thus, good engine operability is always acquired.

Abstract: In a fuel injection control method of an engine which an intake air flow rate is estimated by a predetermined calculating method, using data on detected intake pipe pressure and engine rotating speed, a fuel injection time is determined by a predetermined calculating method, using the intake air flow rate, and a deviation from a target engine rotating speed, and an injector driving signal is outputted by a fuel injection control device, the fuel injection time is obtained by adding a battery voltage fluctuation correction time, and a transient correction injection time which corrects a deviation from the target engine rotating speed, which is obtained by a predetermined calculating method, to a basic injection time obtained by a predetermined calculating method.

Abstract: An engine revolution number is controlled by operating opening and closing of a throttle valve by an engine revolution number control means on the basis of a deviation between a detected engine revolution number and a target engine revolution number, and air-fuel ratio control means applies the engine revolution number and the intake air flow rate to a predetermined numerical formula which is derived from a plurality of sets of data groups including the intake air flow rate and air-fuel ratio, which are obtained from a predetermined experiment model, and expresses the relationship between each data, to thereby calculate a fuel injection time for realizing a target air fuel ratio. A target air fuel ratio is thus realized while minimizing any delay of a response even during a transient operation, and thus, good engine operability is always acquired.