Cylinder judging device for internal combustion engine

Internal-combustion engines – Charge forming device – Fuel injection system

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Details

12340658, 73116, F02P 504

Patent

active

059794135

DESCRIPTION:

BRIEF SUMMARY
TECHNICAL FIELD

The present invention relates to a cylinder discriminating apparatus for an internal combustion engine, for reliably identifying, with a simple implementation, the stroke phase of each cylinder in a multiple cylinder type internal combustion engine with the internal combustion engine not being stopped.


BACKGROUND ART

In a multiple cylinder type internal combustion engine, which has a plurality of cylinders, the use of a so-called multi-point injection (MPI) system, in which an injector for fuel injection is arranged for each cylinder, is generally know. An MPI system provides a high degree of freedom of air intake system, and easily achieves a high output. For this reason, the MPI system attracts attention as a main system for electronic controlled fuel injection.
An MPI system uses a group injection method in which a plurality of cylinders are grouped in advance and the injectors for each cylinder group are operated simultaneously to inject fuel, or a sequential injection method in which a plurality of injectors are operated independently to sequentially inject fuel into each cylinder. Whichever fuel injection method may be used, it is desirable to set the fuel injection timing so as to avoid a stroke having the possibility of deteriorated combustion and deteriorated exhaust gas, and, more particularly, the intake stroke.
In order to set the fuel injection timing for each cylinder or each cylinder group so as to avoid the above mentioned problem of the intake stroke, it is important to determine in which stroke of the combustion cycle each cylinder of internal combustion engine is in. Specifically, a combustion cycle consisting of four strokes of intake, compression, combustion (expansion), and exhaust is repeated in each cylinder of internal combustion engine. For each cylinder, moreover, the timing is set in advance to enter the combustion stroke sequentially at equal intervals. Therefore, if it can be determined in which stroke the particular cylinder is, or inversely which cylinder is in the particular stroke, it can be known in which stroke each of the remaining cylinders is.
The fuel injection described above before is controlled on the basis of such a cylinder discrimination result. At the start of the internal combustion engine, there scarcely arises a problem even if fuel is simultaneously injected into plural cylinders, so that, generally, it is necessary only that the cylinder discrimination is made after cranking is completed.
However, the requirement for cylinder discrimination necessary to control the ignition system is very severe as compared with the cylinder discrimination necessary to control the fuel injection. Incidentally, a high voltage distribution system, which ignites cylinders in sequence by distributor, presents no problem because the cylinder operated by ignition is automatically selected by the distributor. For a low voltage distribution system, which does not use a distributor, it is necessary to make cylinder discrimination as quickly as possible at the engine start so as to determine which ignition coil (cylinder) should be energized.
Conventionally, in order to control the ignition and fuel injection timing for each cylinder, and further to detect the rotational speed, a sensor is mounted on the rotating output shaft (crankshaft) of the internal combustion engine to detect the crank angle. Since the crankshaft rotates two turns in one combustion cycle, however, cylinder cannot be identified directly from the output of the crank angle sensor. A cylinder group consisting of two cylinders with a 360.degree. mutually different stroke phase can be identified from the output of the crank angle sensor, though. Conventionally, therefore, a sensor is also mounted on a camshaft rotating in connection with the crankshaft to determine a 360.degree. difference in stroke phase. Thus, the cylinder can be discriminated by using the signal from the cam sensor and that from the crank angle sensor. The camshaft, which opens and closes the intake and exhaust valves for eac

REFERENCES:
patent: 4515131 (1985-05-01), Suzuki et al.
patent: 5067462 (1991-11-01), Iwata et al.
patent: 5452604 (1995-09-01), Namiki et al.
patent: 5522256 (1996-06-01), Hashimoto et al.

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