Disclosed is a control apparatus for controlling power supply from a power source to a glow plug, including a plurality of semiconductor switching elements arranged to turn on and of power supply to the glow plug, a temperature fuse actuated by a temperature rise thereof to interrupt power supply to the semiconductor switching elements, a failure detection portion that detects the occurrence or non-occurrence of an ON failure in each of the semiconductor switching elements, and a control portion that performs drive control of the semiconductor switching elements. When the failure detection portion detects the ON failure in at least one of the semiconductor switching elements, the control portion increases the amount of heat generation of either the at least one of the semiconductor switching elements in which the ON failure is detected or any of the semiconductor switching elements in which the ON failure is not detected.

There are described methods and systems for operating a glow plug. The method comprises monitoring a glow plug current; applying a nominal voltage V.sub.N to the glow plug when the glow plug current is between an upper threshold I.sub.1 and a lower threshold I.sub.2<I.sub.1; applying a voltage V.sub.H>V.sub.N to the glow plug when the glow plug current exceeds the upper threshold I.sub.1; and applying substantially no voltage to the glow plug when the glow plug current falls below the lower threshold I.sub.2.

A residual gas ignitor for use in igniting a fuel-air mixture within a main combustion chamber of an engine. The residual gas ignitor includes at least one inlet/outlet port, a residual gas ignitor chamber for receiving a combustion gas from the main combustion chamber, an ignitor valve for opening and closing the at least one inlet/outlet port, an actuator for actuating the ignitor valve to open and close the at least one inlet/outlet port, a valve guide for keeping the ignitor valve in a correct orientation within the residual gas ignitor, a preload spring for being in compression when the actuator disposes the ignitor valve into the closed position, and a heating element for maintaining or increasing a temperature of the combustion gas while the combustion gas is in the residual gas ignitor chamber. The residual gas ignitor may be used in engines for initiating combustion of fuel-air mixtures.

A method for operating a glow plug includes controlling a temperature of the glow plug by switching between applying a voltage V.sub.H and applying a voltage V.sub.N<V.sub.H to the glow plug. Applying the voltage V.sub.H and applying the voltage V.sub.N causes a glow plug current to oscillate about a glow plug current threshold. The glow plug current threshold is associated with one of the voltage V.sub.H and the voltage V.sub.N. The method includes monitoring the glow plug current at the one of the voltage V.sub.H and the voltage V.sub.N.

A method for operating a glow plug includes controlling a temperature of the glow plug by switching between applying a voltage V.sub.H and applying a voltage V.sub.N<V.sub.H to the glow plug. Applying the voltage V.sub.H and applying the voltage V.sub.N causes a glow plug current to oscillate about a glow plug current threshold. The glow plug current threshold is associated with one of the voltage V.sub.H and the voltage V.sub.N. The method includes monitoring the glow plug current at the one of the voltage V.sub.H and the voltage V.sub.N.

There is provided a construction machine that draws attention from the surroundings of the machine body when the prime mover is started and that can have the operator reliably confirm the surroundings of the machine body before the prime mover is started. An engine start control section 23 of a main controller 22 inhibits an engine 18 from starting when a key switch 12 is operated while a horn switch 21 is not operated, inhibits the engine 18 from starting when the key switch 12 is operated for the duration until a first set time T1 elapses after the operation of the horn switch 21 has been finished, permits the engine 18 to start in a case the key switch 12 is operated for the duration until a second set time T2 elapses after the first set time T1 has elapsed, and inhibits the engine 18 again from starting when the key switch 12 is operated if the engine 18 is not started for the duration until the second set time T2 elapses.

There is provided a construction machine that draws attention from the surroundings of the machine body when the prime mover is started and that can have the operator reliably confirm the surroundings of the machine body before the prime mover is started. An engine start control section 23 of a main controller 22 inhibits an engine 18 from starting when a key switch 12 is operated while a horn switch 21 is not operated, inhibits the engine 18 from starting when the key switch 12 is operated for the duration until a first set time T1 elapses after the operation of the horn switch 21 has been finished, permits the engine 18 to start in a case the key switch 12 is operated for the duration until a second set time T2 elapses after the first set time T1 has elapsed, and inhibits the engine 18 again from starting when the key switch 12 is operated if the engine 18 is not started for the duration until the second set time T2 elapses.

There is provided a construction machine that draws attention from the surroundings of the machine body when the prime mover is started and that can have the operator reliably confirm the surroundings of the machine body before the prime mover is started. An engine start control section 23 of a main controller 22 inhibits an engine 18 from starting when a key switch 12 is operated while a horn switch 21 is not operated, inhibits the engine 18 from starting when the key switch 12 is operated for the duration until a first set time T1 elapses after the operation of the horn switch 21 has been finished, permits the engine 18 to start in a case the key switch 12 is operated for the duration until a second set time T2 elapses after the first set time T1 has elapsed, and inhibits the engine 18 again from starting when the key switch 12 is operated if the engine 18 is not started for the duration until the second set time T2 elapses.

There is provided a construction machine that draws attention from the surroundings of the machine body when the prime mover is started and that can have the operator reliably confirm the surroundings of the machine body before the prime mover is started. An engine start control section 23 of a main controller 22 inhibits an engine 18 from starting when a key switch 12 is operated while a horn switch 21 is not operated, inhibits the engine 18 from starting when the key switch 12 is operated for the duration until a first set time T1 elapses after the operation of the horn switch 21 has been finished, permits the engine 18 to start in a case the key switch 12 is operated for the duration until a second set time T2 elapses after the first set time T1 has elapsed, and inhibits the engine 18 again from starting when the key switch 12 is operated if the engine 18 is not started for the duration until the second set time T2 elapses.

An internal combustion engine includes a combustion chamber with a cylinder head, a cylinder, and a piston. The internal combustion engine also includes at least one intake valve and at least one exhaust valve that are connected to the combustion chamber, a fuel injector that injects fuel into the combustion chamber, at least two ignition devices arranged in the combustion chamber, and control means that control the valves, the injector, and the ignition means. The control means operate the engine according to different combustion modes including a controlled ignition combustion mode, a compression ignition combustion mode, and an assisted compression ignition combustion mode. The control means activate the ignition means in the assisted compression ignition combustion mode.