An engine system includes: an ammonia engine; a reforming device that has a reforming catalyst for cracking ammonia gas into hydrogen and configured to reform ammonia gas to generate reformed gas containing hydrogen; and a control unit. The control unit includes: a purge controller configured to control a reforming injector so as to be closed and control a reforming throttle valve so as to be opened, after an ignition switch gives an instruction of a stop of the ammonia engine; and an engine stop controller configured to control main injectors so as to be closed, after the ignition switch gives the instruction of the stop of the ammonia engine.

An engine system includes: an ammonia engine; a reforming device that has a reforming catalyst for cracking ammonia gas into hydrogen and configured to reform ammonia gas to generate reformed gas containing hydrogen; and a control unit. The control unit includes: a purge controller configured to control a reforming injector so as to be closed and control a reforming throttle valve so as to be opened, after an ignition switch gives an instruction of a stop of the ammonia engine; and an engine stop controller configured to control main injectors so as to be closed, after the ignition switch gives the instruction of the stop of the ammonia engine.

A two-stroke combustion engine comprising a user-operated throttle control, an adjustable valve arranged to control one or more air intakes of the combustion engine, and a control unit arranged to control a state of the adjustable valve, wherein the combustion engine is arranged to operate in a first idle mode at an idle engine speed below a clutch engagement engine speed when the user-operated throttle control is not engaged, wherein the combustion engine is arranged to operate in a second idle mode at a target engine speed above the clutch engagement engine speed when the user-operated throttle control is engaged and when the engine is not subject to an external load, the control unit being arranged to control the state of the adjustable valve to maintain engine speed at the target engine speed when the engine operates in the second idle mode.

The present disclosure relates to a carburetor assembly (7) comprising a control unit (17), an air channel (8), a throttle valve (9), a choke valve (10), a pulsed fuel valve (11), and a fuel supply line (12). The control unit (17) is adapted to control the fuel valve (11) to supply fuel in accordance with a certain start setting, where the choke valve (10) can be open or closed. The carburetor assembly (7) comprises a rotation angle detector assembly (20) with a choke detector part (29) that is mounted to a choke shaft (30) that is connected to the choke valve (10) such that the choke detector part (29) is arranged to rotate together with the choke valve (10). The rotation angle detector assembly (20) further comprises a choke sensor device (23, 33) that is connected to the control unit (17) and can be affected by the choke detector part (29) such that the choke sensor device (23, 33) provides different output signals to the control unit (17) in dependence of whether the choke valve (10) is open or closed.

Systems and methods for operating an engine that includes two throttles that are arranged in parallel to deliver air into a single intake manifold are described. In one example, a first throttle and a second throttle are opened according to a value of a variable that changes as a function of a requested engine air flow.

Systems and methods for operating an engine that includes two throttles that are arranged in parallel to deliver air into a single intake manifold are described. In one example, a first throttle is opened before a second throttle during a first condition and the second throttle is opened before the first throttle during a second condition. The throttles may be operated in this way to ensure even operation of the throttles.

Systems and methods for operating an engine that includes two throttles that are arranged in parallel to deliver air into a single intake manifold are described. In one example, a first throttle and a second throttle are opened according to a value of a variable that changes as a function of a requested engine air flow.

An engine includes: an engine main body including a plurality of cylinders; a plurality of throttle valves positioned on intake sides of the plurality of cylinders; and a controller configured to control opening and closing operation of the plurality of throttle valves. Output of a part of the plurality of cylinders is larger than output of rest of the plurality of cylinders. And the controller opens a part of the throttle valves upstream of the part of the plurality of cylinders at a lower speed than rest of the throttle valves upstream of the rest of the plurality of cylinders.

Systems and methods for operating an engine that includes two throttles that are arranged in parallel to deliver air into a single intake manifold are described. In one example, a first throttle is opened before a second throttle during a first condition and the second throttle is opened before the first throttle during a second condition. The throttles may be operated in this way to ensure even operation of the throttles.

Systems and methods for operating an engine that includes dual throttles are disclosed. In one example, positions of the dual throttles may be adjusted to limit flow of hydrocarbons from a hydrocarbon trap during cold engine starting so that an amount of hydrocarbons that reach atmosphere may be reduced. Each of the dual throttles may be positioned in a separate engine air intake passage.