Internal-combustion engines – Spark ignition timing control – Electronic control
Reexamination Certificate
2000-08-08
2002-03-19
Solis, Erick (Department: 3747)
Internal-combustion engines
Spark ignition timing control
Electronic control
C123S406620
Reexamination Certificate
active
06357418
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
This invention pertains to an internal combustion engine control system adapted to control an ignition system or a fuel injection system for a four cycle internal combustion engine by means of an electronic control unit using a microcomputer and also pertains to an apparatus for practicing the system.
BACKGROUND OF THE INVENTION
A four cycle internal combustion engine comprises a plurality of cylinders, a crank shaft rotationally driven by pistons moving in the cylinders, respectively, a cam shaft driving an air supply valve and an exhaust valve rotated in synchronization with the crank shaft at half a revolution rate of the crank shaft and an ignition system to ignite each of the cylinders in accordance with ignition signals therefor whereby a combustion cycle of four strokes including an explosion stroke, an exhaust stroke, an intake or suction stroke and a compression stroke is repeated to rotate the crank shaft thereby.
In order to sufficiently draw an output power out of the four cycle internal combustion engine, improve on fuel consumption and enhance purification of the exhaust gas, an ignition position of the internal combustion engine (a rotary angle position of the crank shaft at which an ignition operation is made) and a supply amount of fuel are required to be controlled in a highly precise manner in accordance with various control conditions such as a revolution rate (r.p.m) of the engine.
To this end, the latest four cycle internal combustion engine comprises a fuel injection system including an injector (an electro-magnetic fuel injection valve) provided for the respective cylinders, a fuel pump to supply a fuel to the injector and an injector drive circuit to supply a drive current to the injector and also a contactless ignition system whereby an electronic control unit (ECU) including a microcomputer controls the fuel injector system and the ignition system.
The injector for the fuel injection system comprises an injector body having a fuel injection port at a leading end thereof, a solenoid (an electromagnet) disposed within the injector body and a valve adapted to open the fuel injection port while the predetermined drive current is supplied to the solenoid whereby the fuel is supplied from the fuel pump to the injector body under predetermined pressure. The injector is mounted on an intake pipe of the engine, for example and serves to inject the fuel through the fuel injection port by opening the valve while the drive current is supplied to the solenoid from the injector drive circuit. The fuel injected within the intake pipe is combined with air entering the intake pipe through a throttle valve and supplied within the cylinders when intake valves thereof are opened.
Although an injection amount of the fuel from the injector is based on the product of the time during which the valve is opened and the fuel pressure provided by the fuel pump, it is generally determined on the injection time (a signal width of an injection instruction signal) because the fuel pressure is kept constant by a pressure regulator. Accordingly, in the internal combustion engine in which the fuel is supplied by the fuel injection system, the amount of the fuel supplied to the engine has been controlled by adjusting the signal width of the injection instruction signal.
In case that the fuel is injected into the intake pipe of the four cycle internal combustion engine, it is generally known that the fuel is desirably injected over the exhaust stroke and the intake stroke of the engine for precisely controlling the fuel consumption and the component of the exhaust gas. Accordingly, a position where the injection instruction signal is supplied to the injector drive circuit (a position where the fuel injection starts) should be set at a proper position within a scope of the rotary angle of the crank shaft corresponding to the exhaust stroke.
The contactless ignition system for igniting the internal combustion engine comprises an ignition plug mounted on each of the cylinders of the engine, an ignition coil having a secondary coil connected to the ignition plug for each of the respective cylinders and an ignition drive circuit to give an abrupt change in a primary current of the ignition coil in accordance with the ignition signals for the respective cylinders for inducing an igniting high voltage across the secondary coil of the ignition coil at the ignition position of the internal combustion engine (the rotary angle position of the crank shaft).
In general, the ignition coil is provided for every cylinder of the internal combustion engine, but one ignition coil is provided for a set of two cylinders having their ignition positions provided in a manner far away to each other at an crank angle of 360° in some internal combustion engines having an even number of cylinders such as two or four cylinders. For instance, in the four cycle four cylinder internal combustion engine, the ignition is made in order of the first, third, fourth and second cylinders. In this case, the first and fourth cylinders having the ignition positions far away from each other at the crank angle of 360° are as a first set of cylinders while the second and third cylinders are as another set of cylinders. Thus, there are provided two ignition coils including a first ignition coil for the first and fourth cylinders and a second ignition coil for the second and third cylinders. The secondary coils of the ignition coils have both ends connected to the non-grounding terminals of the ignition plugs for the two corresponding cylinders.
In case that the common one ignition coil is provided for the two cylinders having the ignition position far away from each other at the crank angle of 360°, the coil is referred as to “simultaneous ignition coil”, a secondary coil of which induces the igniting high voltage to be applied across the two ignition plugs of the two cylinders. In this case, the ignition operation (the operation of spark discharging the high voltage through the ignition plugs) is simultaneously made in the two cylinders, but in the four cycle internal combustion engine, one of the two cylinders having the ignition positions far away from each other at the crank angle of 360° is at a normal ignition position when another cylinder is at an end of the exhaust stroke where the spark of another cylinder can never contribute to the ignition of the fuel. Thus, it will be noted that the operation of the engine has no trouble even though the two cylinders having the ignition position far away from each other at the crank angle of 360° are simultaneously ignited.
A capacitor discharge type circuit and a current interruption type circuit are known as the ignition drive circuit provided at the primary side of the ignition coil. The capacitor discharge type ignition drive circuit comprises an igniting capacitor provided at the primary side of the ignition coil to be charged at one polarity at a position advanced relative to the ignition position and a primary current controlling switch turned on when the ignition signal is given to discharge the charge of the capacitor through the primary coil of the ignition coil whereby the abrupt change in the primary current of the ignition coil is generated by discharging the igniting capacitor to induce the igniting high voltage.
The current interruption type ignition drive circuit comprises a power source to supply the primary current to the ignition coil and a primary current controlling switch turned on by the ignition signal at the position advanced relative to the ignition position. The ignition drive circuit makes the primary current flow through the ignition coil when it receives the ignition signal and interrupts the primary current controlling switch when the ignition signal is extinguished at the ignition position whereby the igniting high voltage is induced in the secondary coil of the ignition coil. As the current interruption type ignition drive circuit are used a battery type one having a battery used for the power source and a generating c
Aoki Narutoshi
Uemura Kiyoshi
LandOfFree
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