An engine system is provided, which includes a main combustion chamber, a subchamber, an injector that injects fuel into the main combustion chamber, a main spark plug that ignites a mixture gas inside the main combustion chamber, and a subspark plug that ignites the mixture gas inside the subchamber, an throttle valve, and a control device. In a first range, compression self-ignition combustion of the mixture gas inside the main combustion chamber is performed. In a second range, flame propagation combustion is performed while setting an air-fuel ratio of the mixture gas lower than that in the first range. Immediately after the transition from the first range to the second range, only the subignition is performed, or the subignition and the main ignition are performed while setting a timing of the main ignition to a timing same as or retarded from the subignition.

One embodiment is a system comprising an internal combustion engine having one or more non-dedicated cylinders and one or more dedicated EGR cylinders configured to provide EGR to the engine via an EGR loop, a first spark plug coupled to each of the one or more non-dedicated cylinders, and a second spark plug coupled to each of the one or more dedicated EGR cylinders, wherein the second spark plug has a physical or dimensional characteristic that is different from the first spark plug. In certain forms each of the non-dedicated cylinders has only one of a first type of spark plug and each of the dedicated EGR cylinders has only one of a second type of spark plug. One or more of the characteristics that may vary between the first and second types of spark plugs include spark gap, electrode diameter, heat range, and ion sensing capability.

One embodiment is a system comprising an internal combustion engine having one or more non-dedicated cylinders and one or more dedicated EGR cylinders configured to provide EGR to the engine via an EGR loop, a first spark plug coupled to each of the one or more non-dedicated cylinders, and a second spark plug coupled to each of the one or more dedicated EGR cylinders, wherein the second spark plug has a physical or dimensional characteristic that is different from the first spark plug. In certain forms each of the non-dedicated cylinders has only one of a first type of spark plug and each of the dedicated EGR cylinders has only one of a second type of spark plug. One or more of the characteristics that may vary between the first and second types of spark plugs include spark gap, electrode diameter, heat range, and ion sensing capability.

A combustion control system and method for a turbulent jet ignition engine is presented. A controller is configured to receive a torque request, determine a target spark stagger based on a first spark from a first ignition device and a second spark from a second ignition device, determine an adjusted maximum brake torque (MBT) based on the spark stagger, determine a delta spark based on a difference between the adjusted MBT and an actual leading spark from the first and second ignition devices, determine a torque efficiency based on the delta spark, estimate an actual torque, and command a first and a second spark timing from the first and second ignition devices to satisfy the torque request.

A combustion control system and method for a turbulent jet ignition engine is presented. A controller is configured to receive a torque request, determine a target spark stagger based on a first spark from a first ignition device and a second spark from a second ignition device, determine an adjusted maximum brake torque (MBT) based on the spark stagger, determine a delta spark based on a difference between the adjusted MBT and an actual leading spark from the first and second ignition devices, determine a torque efficiency based on the delta spark, estimate an actual torque, and command a first and a second spark timing from the first and second ignition devices to satisfy the torque request.

An engine system is provided, including a controller which controls devices of an engine at a given engine speed so that, when a demanded engine load is a first load, a mass ratio (G/F) of intake air inside a cylinder (containing fresh air and burnt gas) to fuel is a first G/F and mixture gas inside the cylinder combusts by flame-propagation, when the demanded load is a second load (<the first load), the G/F is a second G/F (>the first G/F) and an injection center-of-gravity is at a timing such that the entire mixture gas combusts by CI combustion, and when the demanded load is between the first and second loads, the G/F is at a third G/F (between the first and second G/Fs) and the injection center-of-gravity is at a later timing such that at least part of the mixture gas combusts by the CI combustion.

An engine system is provided, including a controller which controls devices of an engine at a given engine speed so that, when a demanded engine load is a first load, a mass ratio (G/F) of intake air inside a cylinder (containing fresh air and burnt gas) to fuel is a first G/F and mixture gas inside the cylinder combusts by flame-propagation, when the demanded load is a second load (<the first load), the G/F is a second G/F (>the first G/F) and an injection center-of-gravity is at a timing such that the entire mixture gas combusts by CI combustion, and when the demanded load is between the first and second loads, the G/F is at a third G/F (between the first and second G/Fs) and the injection center-of-gravity is at a later timing such that at least part of the mixture gas combusts by the CI combustion.

A method of providing spark ignition for an engine or other equipment having a combustion chamber. A radio frequency wave or a microwave (RF/microwave) generator delivers radio frequency waves or microwaves to a transmit antenna inside the combustion chamber. At least one RF/microwave receive antenna is attached to an internal surface of the combustion chamber and comprises two or more RF/microwave focusing features with a spark gap between them. The transmit antenna wirelessly energizes the receive antenna, which generates a spark between the two focusing features.

An engine system is provided, which includes a cylinder block, a cylinder head, a piston, a main combustion chamber, a subchamber, an injector that injects fuel into the main combustion chamber, a main spark plug that ignites a mixture gas inside the main combustion chamber, a subspark plug that ignites the mixture gas inside the subchamber, and a controller electrically connected to the injector and the main spark plug and the subspark plug. In a low-load range where an engine load is below a given reference load, the controller controls the main spark plug and the subspark plug so that the subignition is performed after performing the main ignition, and the controller retards the timing of the subignition in a high-speed range where an engine speed is above a given reference engine speed, compared with a low-speed range below the reference engine speed.

An engine system is provided, which includes a cylinder block, a cylinder head, a piston, a main combustion chamber, a subchamber, an injector that injects fuel into the main combustion chamber, a main spark plug that ignites a mixture gas inside the main combustion chamber, a subspark plug that ignites the mixture gas inside the subchamber, and a controller electrically connected to the injector and the main spark plug and the subspark plug. In a low-load range where an engine load is below a given reference load, the controller controls the main spark plug and the subspark plug so that the subignition is performed after performing the main ignition, and the controller retards the timing of the subignition in a high-speed range where an engine speed is above a given reference engine speed, compared with a low-speed range below the reference engine speed.