JPH0510227A - Cylinder discrimination device of internal combustion engine - Google Patents

Abstract

PURPOSE:To prevent erroneous judgement of a cylinder at the time of switching a valve timing in the case when a cylinder discrimination sensor is installed on a cam shaft, in the case of an engine provided a variable valve timing mechanism which relatively varies a phase in relation to a cam shaft and a crank shaft. CONSTITUTION:A variable valve timing mechanism 15 is provided between a cam shaft 12 and a crank shaft 14. A cylinder discrimination sensor 17 is provided at the rear end of a cam shaft 12, and a standard position detecting sensor 20 and an angle detection sensor 21 are arranged at the rear end of the crank shaft 14. Reading of an output signal of the cylinder discrimination sensor 17 is stopped at the time of switching a valve timing, and discrimination of the cylinder is performed based on the stored cylinder discrimination condition.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cylinder discriminating apparatus for discriminating which cylinder corresponds next to an ignition cylinder in a multi-cylinder internal combustion engine.

[0002]

2. Description of the Related Art For example, in ignition timing control of an internal combustion engine or sequential injection type fuel injection control for injecting fuel at each timing for each cylinder, it is necessary to determine which cylinder corresponds to the ignition cylinder next. There is. Therefore, in general, a photoelectric or electromagnetic cylinder discrimination sensor is provided as a part of the crank angle sensor. The cylinder discriminating sensor has different pulse widths and pulse numbers output for each cylinder, for example, and the control unit discriminates the cylinders based on the length and number of the pulses. Further, this cylinder discrimination sensor is often provided for a camshaft which makes one rotation at a crank angle of 720 °, as disclosed in JP-A-61-144509.

As is well known, the camshaft of an internal combustion engine is linked to the crankshaft via a timing belt or a timing chain. In recent years, however, the camshaft is variable to relatively change the phase of the camshaft with respect to the crankshaft. A valve timing mechanism has been proposed.
For example, as disclosed in Japanese Patent Laid-Open No. 59-120707, this is provided in the cam pulley portion around which the timing belt is wound, and hydraulically rotates the pulley outer peripheral portion and the cam shaft relative to each other by a fixed angle. The opening / closing timing of the intake / exhaust valve can be changed.

[0004]

However, if the above-mentioned variable valve timing mechanism is applied to the camshaft provided with the above-mentioned cylinder discrimination sensor, the camshaft is irrelevant to the crank angle when the phase is switched by the variable valve timing mechanism. Since the rotation of the cylinder discriminating sensor causes the pulse width of the pulse signal output from the cylinder discrimination sensor to change, the cylinder may be erroneously determined.

[0005]

A cylinder discriminating apparatus for an internal combustion engine according to the present invention, as shown in FIG. 1, includes a variable valve timing mechanism 1 for relatively changing the phase of a camshaft with respect to a crankshaft, and the cam. A cylinder discrimination sensor 2 provided on the shaft and outputting a pulse signal different for each cylinder, and a reference position detection sensor 3 provided on the crankshaft and outputting a pulse signal at a reference position of a specific cylinder, In an internal combustion engine that is provided for a crankshaft and that includes an angle detection sensor 4 that outputs a pulse signal for each unit crank angle, the first ignition cylinder that determines the next ignition cylinder based on the output signal of the cylinder determination sensor 2 Of the cylinder discrimination means 5, the means 6 for detecting the switching of the variable valve timing mechanism 1, and the cylinder discrimination state immediately before the switching. And means 7 for 憶 is characterized in that a second cylinder determining means 8 for determining the next ignition cylinder above after switching a predetermined period, and said storage contents and the crank angle from.

[0006]

Since the cylinder discrimination sensor 2 outputs different pulse signals for each cylinder, the cylinder discrimination sensor 2 is normally used.
The next ignition cylinder is discriminated by the first cylinder discriminating means 5 based on the output signal of

On the other hand, the variable valve timing mechanism 1
When the switching is performed, the second ignition cylinder is discriminated by the second cylinder discriminating means 8 based on the cylinder discrimination state immediately before the switching and the crank angle stored in the storage means 7.
That is, the pulse signal of the cylinder discrimination sensor 2 is temporarily ignored, and the ignition cylinder is discriminated according to a predetermined ignition order.
The crank angle can be obtained not only by the output signal of the angle detection sensor 4 but also by dividing the output signal of the reference position detection sensor 3.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings.

FIG. 2 is a structural explanatory view showing an embodiment in which the cylinder discriminating apparatus according to the present invention is applied to, for example, an in-line 4-cylinder internal combustion engine 11, in which a camshaft 12 constituting an OHC type valve operating mechanism is The variable valve timing mechanism 1 is interlocked with the crankshaft 14 via the timing belt 13 and is attached to the pulley portion at the front end of the camshaft 12.
5 are provided. This variable valve timing mechanism 1
5 is a camshaft 1 and a camshaft 1 by hydraulic pressure.
2 is configured to rotate relative to each other by a constant angle (for example, about 10 ° CA), whereby the phase of the camshaft 12 with respect to the crankshaft 14 changes. The variable valve timing mechanism 15
Is controlled to be ON or OFF via a solenoid valve (not shown) based on a control signal from the control unit 16.

A photoelectric cylinder discrimination sensor 17 is attached to the rear end of the camshaft 12. In this cylinder discrimination sensor 17, a light emitting element and a light receiving element are arranged so as to face each other with a disc-shaped plate 18 as shown in FIG. 3, and a pulse signal, that is, a cylinder discrimination signal is generated by light passing through a slit 19 of the plate 18. The slit 19 is output every 90 ° corresponding to each cylinder.
Individually formed, the width is slightly different. That is, a pulse signal having a different pulse width is output for each cylinder.

A reference position detecting sensor 20 and an angle detecting sensor 21 using an electromagnetic pickup are arranged at the rear end of the crankshaft 14 connected to a transmission (not shown) so as to face the signal rotor 22. There is. As shown in FIG. 4, the signal rotor 22 has 180 teeth 23 formed at equal intervals around the signal rotor 22 and has one protrusion 24. In the angle detection sensor 21,
A pulse signal is generated by the teeth 23 every 2 ° CA. By shaping the waveform of this output signal, an angle signal whose rise and fall are in units of 1 ° CA can be obtained. Further, the reference position detection sensor 20 generates a pulse signal at every 360 ° CA by the projection 24, and the reference position signal indicates the reference position of a specific cylinder (for example, # 1 cylinder).

The output signals of these sensors 17 and 20 are input to the control unit 16, and the ignition cylinder is discriminated and the crank angle is detected based on these signals. Then, the control unit 16 performs ignition timing control, fuel injection control and the like based on the cylinder discrimination and the crank angle.

The flow chart of FIG. 5 shows a flow of processing such as cylinder discrimination executed in the control unit 16, which will be described below. First, in step 1, it is determined whether or not the reference position signal output by the reference position detection sensor 20 is normal. Further, in step 2, it is determined whether or not the angle signal output by the angle detection sensor 21 is normal, and in step 3, it is determined whether or not the cylinder discrimination signal output by the cylinder discrimination sensor 17 is normal. These determinations can be made based on, for example, whether or not a signal of a predetermined level or higher is output within a certain period.

If there is no abnormality in each of the sensors 17, 20 and 21, the process proceeds to step 4 and the normal mode is selected. In this normal mode, the cylinder discrimination (step 19), the ignition control, and the fuel injection control (step 20) are executed by using the output signals of the sensors 17, 20, 21 respectively according to the intended purpose. .. That is, the next ignition cylinder is determined by the pulse width of the cylinder determination signal, and the crank angle position is obtained by counting the angle signal from the time when the reference position signal or the cylinder determination signal is input.

Further, when it is determined that any one of the sensors is abnormal in steps 1 to 3, similarly, it is sequentially determined whether or not there is an abnormality in the other sensor (steps 5, 6).
8, 11, 13). If only the cylinder discrimination signal is abnormal, the process proceeds from step 3 to step 13 to select the backup mode 1. In the backup mode 1, ignition control and fuel injection control are executed based on the reference position signal and the angle signal (steps 14 and 15). However, in this case, complete cylinder discrimination is not performed, and # 1, # 4
Group control is performed in which fuel injection and ignition are performed in group units of the cylinder group and the # 2 and # 3 cylinder groups. If only the angle signal is abnormal, step 2,
From 11 to step 12, the backup mode 2 is selected. In this backup mode 2, cylinder discrimination (step 1) is performed based on the reference position signal and the cylinder discrimination signal.
9) and ignition control and fuel injection control (step 20) are executed. In this case, the crank angle is obtained, for example, by counting the internal signal obtained by dividing the cylinder discrimination signal. If only the reference position signal is abnormal, the process proceeds from step 1, 5, 6 to step 7 to select the backup mode 3. In the backup mode 3, the cylinder discrimination (step 1) is performed based on the angle signal and the cylinder discrimination signal.
9) and ignition control and fuel injection control (step 20) are executed. In this case, the reference position is obtained from the cylinder discrimination signal. If both the reference position signal and the angle signal are abnormal, the process proceeds from step 1, 5, 8 to step 9 to select the backup mode 4. In the backup mode 4, cylinder discrimination (step 19), ignition control, and fuel injection control (step 20) are executed based on only the normal cylinder discrimination signal. In this case, the crank angle is obtained by counting the internal signal obtained by dividing the cylinder discrimination signal. In this mode, there is a possibility that the cylinder will be erroneously determined when the variable valve timing mechanism 15 performs the switching operation.
The switching operation (abbreviated as VTC in the flowchart) is prohibited (step 10).

In this way, in the steady state, each sensor 1
Appropriate ignition control and fuel injection control are executed using the output signals of 7, 20, and 21. In particular, by providing the backup mode as described above, even if some of the sensors fail, the operation can be continued to the maximum extent. If the above-mentioned backup mode cannot cope with the problem, control is stopped (step 21).

Next, the switching operation of the variable valve timing mechanism 15 will be described. In steps 16 to 18 of FIG. 5, it is repeatedly detected whether or not the variable valve timing mechanism 15 is in a stage immediately before switching. That is, the current ON / OFF state of the variable valve timing mechanism 15 is read (step 16), and then the engine operating conditions (for example, engine speed and basic fuel injection amount) are determined based on the control map of the variable valve timing mechanism 15. Is it in the ON area?
It is determined whether it is in the F area (steps 17 and 18). If this ON / OFF area matches the current state, it is not necessary to perform the switching operation, but if they do not match, it is understood that the switching operation should be performed.

Therefore, when this switching operation is necessary,
The process proceeds from step 22 onward in the flowchart shown in FIG. 6 to stop reading the cylinder discrimination signal at that time (steps 22 and 23). Then, after that, the variable valve timing mechanism 15 is turned ON → OFF or OFF → ON
Is switched (step 24).

After the variable valve timing mechanism 15 is switched in this way, cylinder discrimination (step 25) is performed based on the stored contents, and ignition control and fuel injection control (step 26) are executed. Specifically, since the crank angle from the time of switching is known from the angle signal or the like, the cylinder to be ignited or fuel-injected next is determined from the cylinder discrimination state immediately before switching and the crank angle. This counts the elapsed time T from the switching point of the variable valve timing mechanism 15 (step 27) and continues until the predetermined time T ₀ is reached (step 28). This predetermined time T ₀ is
It is set corresponding to the period until the relative rotation of the camshaft 12 by the hydraulic pressure is completely completed and a stable cylinder discrimination signal is obtained.

Therefore, even when the variable valve timing mechanism 15 is switched, it is possible to continue accurate discrimination of the cylinders, and it is possible to reliably prevent misfire due to misfire.

In the above structure, the cylinder discrimination sensor 17 provided on the camshaft 12 that makes one rotation at 720 ° CA.
Since all cylinders can be completely identified by the above, the cylinder discrimination can be surely started at the maximum rotation of 180 ° CA at the time of starting. Therefore, sequential injection and appropriate ignition can be started early, and startability is improved.

[0022]

As is apparent from the above description, according to the cylinder discriminating apparatus for an internal combustion engine of the present invention, proper ignition control can be performed without causing an erroneous cylinder discrimination during the switching operation of the variable valve timing mechanism. And fuel injection control can be continued.
In other words, the variable valve timing mechanism can be provided even for the camshaft that is the detection target of the cylinder discrimination sensor, and restrictions such as the mounting position of the cylinder discrimination sensor can be reduced.

[Brief description of drawings]

FIG. 1 is a claim correspondence diagram showing a configuration of the present invention.

FIG. 2 is a structural explanatory view showing an embodiment of a cylinder discriminating apparatus according to the present invention.

FIG. 3 is a plan view showing a plate of a cylinder discrimination sensor.

FIG. 4 is a plan view of a signal rotor attached to a crankshaft.

FIG. 5 is a flowchart showing the flow of processing such as cylinder discrimination in this embodiment.

FIG. 6 is a flowchart of the same.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Variable valve timing mechanism 2 ... Cylinder discrimination sensor 3 ... Reference position detection sensor 4 ... Angle detection sensor 5 ... First cylinder discrimination means 6 ... Switching detection means 7 ... Storage means 8 ... Second cylinder discrimination means

Claims (1)

Claim: What is claimed is: 1. A variable valve timing mechanism for relatively changing a phase of a camshaft relative to a crankshaft, and a cylinder discrimination, which is provided for the camshaft and outputs a different pulse signal for each cylinder. A sensor, a reference position detection sensor that is provided for the crankshaft and outputs a pulse signal at a reference position of a specific cylinder, and an angle detection that is also provided for the crankshaft and outputs a pulse signal for each unit crank angle. An internal combustion engine including a sensor; a first cylinder discrimination means for discriminating a next ignition cylinder based on an output signal of the cylinder discrimination sensor; a means for detecting switching of the variable valve timing mechanism;
A means for storing the cylinder discrimination state immediately before the switching, and a second cylinder discrimination means for discriminating the next ignition cylinder from the stored contents and the crank angle for a predetermined period after the switching are provided. Cylinder discriminating device for internal combustion period.