Internal-combustion engines – High tension ignition system – Having engine component position sensor
Reexamination Certificate
2003-01-29
2003-09-02
Mohanty, Bibhu (Department: 3747)
Internal-combustion engines
High tension ignition system
Having engine component position sensor
C123S613000, C123S179100
Reexamination Certificate
active
06612296
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to a control apparatus for an internal combustion engine (hereinafter also referred to simply as the engine) which apparatus is designed for performing identification of cylinders of the engine and control thereof on the basis of crank angle pulse signals related to a crank shaft of the engine mounted on a motor vehicle and cylinder identifying pulse signals related to a cam shaft of the engine. More particularly, the present invention relates to a control apparatus for an internal combustion engine in which the crank angle pulse signal contains unequi-interpulse intervals in correspondence to reference crank angle positions (hereinafter also referred to simply as the reference positions) in a pulse train composed of a large number of equi-interval pulses.
In particular, the present invention is concerned with a control apparatus for the internal combustion engine which apparatus is so designed as to prevent erroneous ignition and fuel injection controls ascribable to erroneous identification of the reference positions and the cylinders which may be brought about by repetitive on/off manipulation of a cranking switch (hereinafter also referred to as the starter switch) in the course of an engine starting operation.
2. Description of Related Art
In general, in the internal combustion engine such as the engine for an automobile or a motor vehicle, it is required to detect on a cylinder-by-cylinder basis the crank angle positions corresponding to rotational positions of the engine in order to control optimally the fuel injection timing as well as the ignition timing for a plurality of engine cylinders in dependence on the engine operation state or condition.
Such being the circumstances, in the conventional control apparatuses for the internal combustion engine known heretofore, electromagnetic sensors are provided in association with a crank shaft and a cam shaft, respectively, of the engine to thereby make available the crank angle pulse signals (also referred to as the crank angle pulses) indicating reference positions for the individual cylinders, respectively, and cam signals (also referred to as the cylinder identifying pulse signals or simply as the cylinder identifying pulses) for identifying discriminatively a specific cylinder and individual cylinders, respectively.
Further, a control unit (referred to as an electronic control unit or ECU in abbreviation) is provided which is so arranged as to discriminatively determine or identify the individual cylinders on the basis of the crank angle pulse signals and the cylinder identifying pulse signals while determining discriminatively the reference positions on a cylinder-by-cylinder basis to thereby arithmetically determine various control quantities for realizing the fuel injection control and the ignition timing control with high accuracy and reliability.
To this end, a crank angle position detecting means is provided which is composed of a disk which is rotatable in synchronism with the crank shaft and a crank angle sensor which is disposed in opposition to the disk. For generating the crank angle pulses which correspond to a plurality of crank angle positions, respectively, the disk is provided with a plurality of detecting members in the form of ring gear teeth with equidistance therebetween along the outer periphery of the disk.
The crank angle sensor is designed to generate as the output signal thereof the crank angle pulses at every predetermined angle (e. g. 10° in terms of the crank angle, represented hereinafter as 10° CA) upon every passing-by of the ring gear teeth (projections) formed in and along the outer peripheral edge of the disk rotating synchronously with the crank shaft.
Thus, the control unit can determine the reference positions (e.g. B75° CA (i.e., 75° CA before the top dead center or TDC) and B5° CA (i.e., 5° CA before the TDC) ) by detecting unequi-interpulse intervals in the crank angle pulse train by measuring the periodical intervals at which the crank angle pulses are generated.
To this end, the detecting member of the crank angle position detecting means is provided with a tooth dropout section (i.e., a peripheral portion in which no tooth is formed) which extends over an angular range of e.g. 30° CA at the reference position of each cylinder (e.g. position 75° or 5° CA before TDC in the compression stroke) so that the unequi-interpulse interval makes appearance in the train of the crank angle pulses generated at an equi-interpulse interval.
Further, the cam shaft which rotates at a ratio of 1/2 relative to the rotation of the crank shaft is provided with a crank angle position detecting means which is constituted by a disk rotatable in synchronism with the cam shaft and a cylinder identification sensor disposed in opposition to the disk. The cylinder identification sensor is so designed as to generate as the output signal thereof the cylinder identification information corresponding to the specific cylinder or individual cylinders.
In this manner, the control unit can detect the reference position corresponding to the partial pulse dropout portion or section (i.e., unequi-interpulse interval) in the crank angle pulse train to thereby realize the cylinder identification with high accuracy and reliability on the basis of combination of the crank angle pulses and the cylinder identifying pulses.
To say in another way, the control unit is capable of discriminatively identifying the individual cylinders on a real-time basis in response to the pulse dropout portions corresponding to the reference crank angle positions and the cylinder identifying pulse signals by detecting on a real-time basis the reference positions on the basis of the crank angle pulse signals.
In this conjunction, it is noted that the unequi-interpulse intervals (i.e., pulse dropout portions) in the crank angle pulse train can be detected correctly and relatively easily so long as the internal combustion engine rotates in the forward direction in a substantially steady state. However, in the course of the cranking operation carried out for starting the operation of the engine, there may arise such situation that the cranking operation is interrupted or stopped before the engine is actually put into operation (i.e., before the engine operation is started) because the starter is manipulated manually.
If the cranking operation should stop before the engine operation is started, then the driving torque is no more transmitted to the internal combustion engine from the starter. Consequently, the piston in the cylinder which is in the compression stroke would not completely be pushed up to the top dead center (TDC).
In that case, the piston may move downwardly from the crank angle position immediately before the TDC position, thus incurring possibly reverse rotation of the engine.
In this conjunction, it is noted that at the time point when the rotation of the internal combustion engine changes from the forward direction to the reverse direction (i.e., at the topmost position of the piston), the engine is caused to stop momentarily or transiently. As a result of this, the input period of the crank angle pulse will become longer. As a consequence, there may unwantedly arise such situation that the period detected at this time point is erroneously recognized as an unequi-interpulse interval or dropout portion (representing the reference position) in the crank angle pulse train.
Furthermore, in the case where the piston can barely clear the top dead center (TDC) in the compression stroke under inertia after the cranking operation has been stopped before the engine operation starts, the engine will then behave as if it stopped momentarily at the top dead center (TDC), which results in that the crank angle pulse period becomes longer at or around the top dead center (TDC) to such extent that the unequi-interpulse interval or dropout portion will erroneously be determined, giving rise to another problem.
Besides, in the case where the cranking opera
Kanazawa Eiji
Makino Tomokazu
Watanuki Takou
Yonezawa Shiro
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