Abstract: A gas engine is provided to control an air-fuel ratio in response to changes in composition of fuel gas. A gas engine 1 includes: an A/F valve 22; a solenoid valve 21; and a control unit 10 configured to perform perturbation using the solenoid valve 21 and set a relationship between an air-fuel ratio and respective opening degrees of the solenoid valve 21 and the A/F valve 22 under a specific engine operation condition using standard fuel gas. During an actual operation in a period in which the engine operation condition is deemed to be stable, when an opening-degree average value b of the solenoid valve 21 deviates from an opening-degree target value a of the solenoid valve 21 set in the control unit 10 under the above operation condition, the control unit 10 adjusts the opening degree of the A/F valve 22 so that the opening-degree average value b equals the opening-degree target value a.

Abstract: This disclosure includes engines that are capable of controlling an air-fuel ratio responsive to rapid changes in the calorific value of a fuel gas. Some engines include an A/F valve, a solenoid valve, and a control unit configured to close the A/F valve when an average opening degree of the solenoid valve is lower than a preset target opening degree, and open the A/F valve when the average opening degree is equal to or higher than the target opening degree. In some engines, when the opening degree of the solenoid valve has been an upper limit opening degree or a lower limit opening degree of the solenoid valve over a predetermined number of times, the control unit is configured to compare with the upper or lower limit opening degree, in lieu of the average opening degree, against the target opening degree to open or close the A/F valve.

Abstract: A control unit performs perturbation using the solenoid valve under a specific engine operation condition by a standard fuel gas, by moving the solenoid valve from a predetermined opening degree to a lean side or a rich side while the A/F valve is opened at a predetermined opening degree. During an actual operation in a period in which the operation condition of the gas engine is deemed to be stable, when an output average value b obtained from an upstream oxygen sensor disposed on an exhaust passage of the gas engine deviates from an output target value a of the upstream oxygen sensor set in the control unit under the above operation condition, the control unit adjusts the opening degree of the A/F valve so that the output average value b equals the output target value a.

Abstract: This disclosure includes engines that are capable of controlling an air-fuel ratio responsive to rapid changes in the calorific value of a fuel gas. Some engines include an A/F valve (22), a solenoid valve (21), and a control unit (10) configured to close the A/F valve when an average opening degree of the solenoid valve is lower than a preset target opening degree, and open the A/F valve when the average opening degree is equal to or higher than the target opening degree. In some engines, when the opening degree of the solenoid valve has been an upper limit opening degree or a lower limit opening degree of the solenoid valve over a predetermined number of times, the control unit is configured to compare with the upper or lower limit opening degree, in lieu of the average opening degree, against the target opening degree to open or close the A/F valve.

Abstract: A gas engine is provided to control an air-fuel ratio in response to changes in composition of fuel gas. A gas engine 1 includes: an A/F valve 22; a solenoid valve 21; and a control unit 10 configured to perform perturbation using the solenoid valve 21 and set a relationship between an air-fuel ratio and respective opening degrees of the solenoid valve 21 and the A/F valve 22 under a specific engine operation condition using standard fuel gas. During an actual operation in a period in which the engine operation condition is deemed to be stable, when an opening-degree average value b of the solenoid valve 21 deviates from an opening-degree target value a of the solenoid valve 21 set in the control unit 10 under the above operation condition, the control unit 10 adjusts the opening degree of the A/F valve 22 so that the opening-degree average value b equals the opening-degree target value a.

Abstract: A control unit performs perturbation using the solenoid valve under a specific engine operation condition by a standard fuel gas, by moving the solenoid valve from a predetermined opening degree to a lean side or a rich side while the A/F valve is opened at a predetermined opening degree. During an actual operation in a period in which the operation condition of the gas engine is deemed to be stable, when an output average value b obtained from an upstream oxygen sensor disposed on an exhaust passage of the gas engine deviates from an output target value a of the upstream oxygen sensor set in the control unit under the above operation condition, the control unit adjusts the opening degree of the A/F valve so that the output average value b equals the output target value a.