Internal-combustion engines – Spark ignition timing control – Electronic control
Reexamination Certificate
1999-03-02
2001-10-16
Lo, Weilun (Department: 3747)
Internal-combustion engines
Spark ignition timing control
Electronic control
C123S090310, C123S090160, C123S090170, C123S406180, C073S116070, C073S117020
Reexamination Certificate
active
06302085
ABSTRACT:
BACKGROUND OF THE INVENTION
(1) Field of the Invention
The present invention relates to an apparatus and method for detecting the crank angle of an engine, and more specifically, to a technique for detecting the crank angle of an engine by use of a camshaft sensor and a crankshaft sensor.
(2) Related Art of the Invention
It was common in the prior art to provide to the engine a camshaft sensor for outputting a pulse signal (reference angle signal) at every crank angle corresponding to a control reference position of each cylinder, and a crankshaft sensor for outputting a pulse signal (unit angle signal) at every unit crank angle. In such case, the unit angle signal immediately after the output of the reference angle signal from the camshaft sensor (or the unit angle signal after, by predetermined numbers, the unit angle signal immediately after said output) is set as a control reference position, utilized to control the ignition timing or the fuel injection timing of the engine.
However, according to the prior art method, the permissible divergence in the timing for generating the signal between the camshaft sensor and the crankshaft sensor was only a unit crank angle at maximum. Therefore, in order to detect the reference position with high accuracy while maintaining the angle resolution of the crankshaft sensor, it was either necessary to minimize to the utmost the dispersion caused when manufacturing or mounting the sensor, or it was necessary to perform an individual adjustment operation.
Moreover, if the reference position was to be detected by the signal from the camshaft sensor in an engine equipped with a variable valve device for variably controlling the valve timing of the intake valve by varying the phase of the intake side camshaft with respect to the crankshaft, it was requested that a camshaft sensor be equipped to the discharge side camshaft whose phase will not be changed with respect to the crankshaft. However, in order to detect the phase of the intake side camshaft, it was necessary to provide a camshaft sensor to the intake side camshaft as well, which led to increase in the number of sensors to be mounted, and as a result, raised the manufacturing cost thereof.
SUMMARY OF THE INVENTION
The present invention was aimed at solving the above-mentioned prior art problems, and the object of the invention is to provide a constitution for detecting a control reference position by the combination of a camshaft sensor for outputting a reference signal and a crankshaft sensor for outputting a unit angle sensor, wherein the permissible range of phase deviation between each detection signals may be widened, without deteriorating the resolution of the unit angle detection.
Further object of the present invention is to provide a constitution utilizing a camshaft sensor for outputting a plurality of signals including a reference angle signal, wherein the reference angle signal may be detected at an early stage and with small operation load.
Another object of the present invention is to provide an engine equipped with a variable valve device for varying the phase of the camshaft with respect to the crankshaft, wherein a camshaft sensor is only equipped to the camshaft being varied of its phase, so as to enable detection of the crank angle and the phase of the camshaft.
In order to achieve the above-mentioned objects, the present invention is so constituted that a crankshaft sensor for outputting a detection signal synchronously with the rotation of a crankshaft outputs a detection signal at every unit crank angle, and at the same time, an omission in the output of the detection signal is set to be generated at every constant crank angle, while a camshaft sensor for outputting a detection signal synchronously with the rotation of a camshaft outputs a detection signal at least at every position where the detection signal to be output by the crankshaft sensor is omitted.
According to such a constitution, the detection signal of the camshaft sensor is output to the portion where the generation interval of the detection signal from the crankshaft sensor is widened due to omission of signal output. Therefore, the permissible range of phase deviation between the detection signal of the camshaft sensor and the detection signal of the crankshaft sensor are widened at positions where the detection signals to be output by the crankshaft sensor are omitted.
In the above case, it is preferable that the positions where detection signals to be output by the crankshaft sensor are omitted should be set to positions of every crank angle corresponding to the stroke phase difference between the cylinders.
According to such a constitution, the detection signals to be output by the crankshaft sensor are omitted at every stroke phase difference between cylinders, and at the same time, detection signals are output by the camshaft sensor at portions where the signals are omitted.
Even further, it is preferable that the camshaft sensor outputs detection signals at every position where the detection signals to be output by the crankshaft sensor are omitted, and subsequent to the output of detection signal to each omitted position, outputs a detection signal for the distinction of the cylinders.
According to such a constitution, the reference position may be detected, and also it may be specified which cylinder the reference position corresponds to based on the detection signal output by the camshaft sensor.
Moreover, it may be preferable to detect the reference position of engine control based on the correlation between the detection signal from the crankshaft sensor and the detection signal from the camshaft sensor.
According to such a constitution, the portion of signal omission of the crankshaft sensor may be specified based on the detection signal from the camshaft sensor, and the reference position of the engine control may be specified with the portion of signal omission as the reference.
In the above case, it is also preferable to count up the value on a counter for counting every output of the detection signal by the crankshaft sensor, and on the other hand, to clear the value on the counter at every output of the detection signal by the camshaft sensor, and based on the result of comparison between the value of the counter and a threshold value stored in advance, to distinguish the detection signals output by the camshaft sensor in correspondence to the positions where the detection signals to be output by the crankshaft sensor are omitted.
According to such a constitution, the detection signals are output by the camshaft sensor to each of the positions where the signals from the crankshaft sensor are omitted, and subsequent to the output of the detection signal, the signal for distinguishing the cylinders are output by the camshaft sensor. Thus, based on the generation cycle of the detection signal from the camshaft sensor, detection may be performed on whether a position corresponds to the signal omitted position. Therefore, the generation cycle is measured by the counted value of the detection signal output by the crankshaft sensor.
Moreover, it is preferable to set the detection signal output by the camshaft sensor corresponding to the signal omission position as reference, and to detect the detection signal of the crankshaft sensor to be set as the reference position for controlling the engine.
According to such a constitution, the detection signal from the crankshaft sensor to be set as the reference position of the engine control may be specified with the signal omission position of the crankshaft sensor as reference.
Actually, the detection signal output by the crankshaft sensor for the first time after the detection signal output by the camshaft sensor corresponding to the signal omission position may be detected as the reference position for the engine control.
Further, in the case a variable valve device for varying the phase of the camshaft with respect to the crankshaft is equipped to the engine, the detection signal may be set to be output by the camshaft sensor at the positi
Sekine Manabu
Watanabe Satoru
Foley & Lardner
Lo Weilun
Unisia Sec's Corporation
Vo Hieu T.
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