Crank angle detection apparatus

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

Reexamination Certificate

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Details

C123S631000, C123S406600

Reexamination Certificate

active

06732713

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a crank angle detection apparatus for detecting the crank angle of the crankshaft of an internal combustion engine, and more particularly, it relates to such a crank angle detection apparatus capable of identifying the rotational direction of the crankshaft.
2. Description of the Related Art
Conventionally, an apparatus for identifying the rotational direction of the crankshaft of an internal combustion engine has been proposed which includes: a first signal generating part and a second signal generating part that generate pulse signals in accordance with the rotational speeds or numbers of revolutions per minute of rotating elements, respectively, which are formed on their outer peripheries with a plurality of teeth arranged at equal intervals in their circumferential direction in such a manner that the signals generated by these signal generating parts become different from each other; a deviation part for obtaining a deviation between the signals generated by the first and second signal generating parts; and a first processing part for processing the deviation between the signals into a signal by means of a filter; wherein the signal thus processed is compared with a determination value to provide a processed pulse signal, from the period of generation of which it is determined whether the internal combustion engine is rotating in the forward direction or in the reverse direction (for instance, see document 1: Japanese patent application laid-open No. Hei 11-117780 (FIG.
1
and FIG.
2
)).
Also, another rotational direction identification apparatus has been proposed which includes a first sensor for generating a crank angle signal at each prescribed angle of rotation of the crankshaft of an internal combustion engine, and a second sensor for generating one reference signal during the time the crankshaft makes two revolutions, the first and second sensors being arranged in such a manner that a phase difference between a pulse of the crank angle signal, which is generated immediately before the generation of a pulse of the reference signal, and that pulse of the reference signal, and a phase reference between a pulse of the crank angle signal, which is generated immediately after the generation of that pulse of the reference signal, and that pulse of the reference signal are made different from each other, so as to determine or identify the rotational direction of the crankshaft based on the magnitude correlation of these phase differences (for instance, see document 2: Japanese patent application laid-open No. Hei 11-62687 (from paragraph No. 0016 to paragraph No. 0017 and FIG.
2
)).
In addition, a further rotational direction identification apparatus has been proposed which includes a reference signal generating part for generating a reference signal at a reference position of an engine crankshaft in synchronization with the rotation of an internal combustion engine, an angle signal generating part for generating a plurality of angle signals or signal pulses more than a predetermined number during one cycle or period of the reference signal in synchronization with the rotation of the internal combustion engine, and an angle signal counting part which is repeatedly reset in synchronization with the reference signal for counting signal pulses of the angle signal, wherein if the count value of the angle signal counting part during a generation period of the reference signal is not equal to a predetermined value, it is determined that the internal combustion engine is rotating in the reverse direction, thus interrupting or cutting at least one of the ignition and the fuel injection (for instance, see document 3: Japanese patent application laid-open No. Sho 62-182463 (second page and FIG.
2
)).
The conventional rotational direction or reverse rotation detection apparatuses as described above is able to determine whether the engine is rotating in the reverse direction, but involves the following problems. That is, it is impossible to generate the reference crank angle signal for accurately controlling the fuel injection, the ignition timing, etc., in accordance with the operating conditions of an internal combustion engine, and hence it is necessary to separately provide a crank angle detection sensor for generating a reference crank angle signal.
Moreover, it is necessary to provide a reference position detection device which is mounted on a camshaft for obtaining a reference signal, in addition to one mounted on the crankshaft.
Further, it is also possible to mount two sensors on the crankshaft separately from each other for obtaining two crank angle signals at the same time, but in this case, it is necessary to install two measurement members on the crankshaft.
Furthermore, when the angle signal begins to be counted from the point or location at which the crank angle position is a half of the reference signal generation period, the count value of the angle signal counting part during the forward rotation becomes equal to that during the reverse rotation, and hence it is impossible to detect the rotational direction or reverse rotation of the engine.
SUMMARY OF THE INVENTION
Accordingly, one object of the present invention is to provide a crank angle detection apparatus which is capable of supplying a crank angle signal as well as identifying the rotational direction of the crankshaft of an internal combustion engine.
Another object of the present invention is to provide a crank angle detection apparatus which is capable of identifying the reverse rotation of an internal combustion engine in a reliable manner even if the engine is started from any crank angle position.
Bearing the above object in mind, according to the present invention, there is provided a crank angle detection apparatus which is constructed as follows. A measurement member is mounted on a crankshaft of an internal combustion engine or a portion that rotates in synchronization with the crankshaft, the measurement member having a plurality of angular position detection portions arranged at equal intervals in a circumferential direction of the crankshaft and a plurality of reference position detection portions at which a part of the angular position detection portions is missing. A crank angle sensor is arranged at a location adjacent to the measurement member for generating a crank angle signal in the form of a train of pulses corresponding to the angular position detection portions and the reference position detection portions. A period detection part detects signal periods of successive pulses of the crank angle signal. A reference position determination part determines a plurality of reference positions based on the signal periods detected by the period detection part. A counting part counts the pulses of the crank angle signal to provide a count value thereof. A rotational direction determination part determines the rotational direction of the crankshaft based on the number of pulses of the crank angle signal counted between the plurality of reference positions.


REFERENCES:
patent: 5979413 (1999-11-01), Ohnuma et al.
patent: 6172500 (2001-01-01), Bicking
patent: 6341253 (2002-01-01), Honda
patent: 62-178734 (1987-08-01), None
patent: 62-182463 (1987-08-01), None
patent: 11-062687 (1999-03-01), None
patent: 11-117780 (1999-04-01), None

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