JP2006220079A - Controller of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To increase the accuracy of an engine control timing detected based on the cam signals of a cam sensor when a crank angle sensor fails. <P>SOLUTION: When the crank angle sensor is normal, a variable valve timing mechanism varying the rotating phase of a cam shaft is controlled to a most retard angle side, and the displacement of the output positions of the cam signals is learned. Then, when the crank angle sensor fails, the detection of the control timing in reference to the cam signals is corrected based on the learned displacement. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a control device for an internal combustion engine that detects engine control timing based on a cam signal output from a cam sensor when a crank angle sensor fails.

In Patent Document 1, when an abnormality occurs in a crank angle sensor, a pseudo reference timing is generated based on a pulse signal output from a cam sensor, and fuel supply control and ignition timing control are continuously executed using the pseudo reference timing. A control device for an internal combustion engine is disclosed.
JP 2001-342888 A

By the way, since the rotation of the crankshaft is transmitted to the camshaft via a timing chain or the like, the detection error of the piston position by the cam sensor that generates a cam signal at every predetermined rotation position of the camshaft is caused by the accumulation of error factors. The detection error becomes larger than that of the angle sensor, and the detection error increases due to the extension of the timing chain or the like.
For this reason, when the crank angle sensor is abnormal, the accuracy of the control reference timing detected based on the pulse signal from the cam sensor is poor, fuel is supplied and ignited at a time significantly different from the required, and the operability of the internal combustion engine is greatly increased. There was a risk of a decline.

  The present invention has been made in view of the above problems, and an object thereof is to improve the accuracy of the engine control timing detected based on the detection signal of the cam sensor when the crank angle sensor is abnormal.

Therefore, the invention according to claim 1 includes a crank angle sensor that outputs a crank angle signal at every predetermined rotational position of the crankshaft, and a cam sensor that generates a cam signal at every predetermined rotational position of the camshaft, An internal combustion engine that detects engine control timing based on the crank angle signal when the crank angle sensor is normal and detects engine control timing based on the cam signal when the crank angle sensor fails In the control device of
When the crank angle sensor is normal, the variation in the output position of the cam signal is learned with reference to the crank angle signal,
When the crank angle sensor fails, the detection of the engine control timing based on the cam signal is corrected according to the variation in the output position of the learned cam signal.

According to this configuration, when the crank angle sensor breaks down, the engine control timing is detected using the cam sensor. However, when the crank angle sensor is normal, the variation in the output position of the cam signal is learned in advance, and the engine is detected based on the cam signal. When the control timing is detected, correction processing based on the learned variation is performed.
Therefore, even if the output position of the cam signal varies, it can be avoided that the detection accuracy of the engine control timing greatly decreases when the crank angle sensor fails.

The invention according to claim 2 includes a variable valve timing mechanism that varies the valve timing of the engine valve by changing the rotational phase of the camshaft relative to the crankshaft, and learning variation in the output position of the cam signal. The variable valve timing mechanism is configured to be controlled in the most retarded angle side.
According to this configuration, when the variation learning of the output position of the cam signal is performed, the variable valve timing mechanism is once controlled to the most retarded angle side which is the default position.

Accordingly, variation learning can be performed without being influenced by the advance angle control state by the variable valve timing mechanism.
Further, when the variable valve timing mechanism is returned to the default position (the most retarded angle side) based on the fact that the rotational phase feedback control cannot be performed when the crank angle sensor fails, the output position variation of the cam signal in this default state is preliminarily determined. It can be detected with high accuracy, and the control timing can be corrected with high accuracy when the crank angle sensor fails.

According to a third aspect of the present invention, the variation learning of the output position of the cam signal is performed while the engine is completely warmed.
According to such a configuration, the learning is performed in a state where the phase shift between the crankshaft and the camshaft is stable by setting the complete warm as a learning condition, and the accuracy of variation learning can be ensured.

Embodiments of the present invention will be described below.
FIG. 1 is a configuration diagram of a four-cylinder gasoline engine in the embodiment.
In FIG. 1, an electronic control throttle 104 that opens and closes a throttle valve 103 b by a throttle motor 103 a is interposed in an intake pipe 102 of an internal combustion engine 101.
Then, air is sucked into the combustion chamber 106 through the electronic control throttle 104 and the intake valve 105.

The intake port 130 of each cylinder is provided with an electromagnetic fuel injection valve 131. When the fuel injection valve 131 is driven to open by an injection pulse signal from an engine control unit (ECU) 114, a predetermined pressure is obtained. The adjusted fuel is injected toward the intake valve 105.
The air-fuel mixture formed in the combustion chamber 106 is ignited and burned by spark ignition by a spark plug (not shown).

The combustion exhaust in the combustion chamber 106 is discharged to the exhaust pipe through the exhaust valve 107, purified by the front catalyst 108 and the rear catalyst 109, and then released into the atmosphere.
The intake valve 105 and the exhaust valve 107 are opened and closed by cams provided on the exhaust side camshaft 110 and the intake side camshaft 134, respectively. The intake side camshaft 134 is provided with a variable valve timing mechanism VTC113. ing.

The variable valve timing mechanism VTC 113 is a mechanism that changes the valve timing of the intake valve 105 by changing the rotational phase of the intake camshaft 134 with respect to the crankshaft 120.
FIG. 2 shows the structure of the variable valve timing mechanism VTC113.
The variable valve timing mechanism VTC 113 is fixed to a sprocket 25 that rotates in synchronization with the crankshaft 120, and a first rotating body 21 that rotates integrally with the sprocket 25 and one end of the intake camshaft 134 by a bolt 22a. And a cylindrical shape that meshes with the inner circumferential surface of the first rotating body 21 and the outer circumferential surface of the second rotating body 22 by the helical spline 26. Intermediate gear 23.

A drum 27 is connected to the intermediate gear 23 via a triple screw 28, and a torsion spring 29 is interposed between the drum 27 and the intermediate gear 23.
The intermediate gear 23 is biased in the retarding direction (left direction in FIG. 2) by a torsion spring 29. When a voltage is applied to the electromagnetic retarder 24 to generate a magnetic force, the intermediate gear 23 passes through the drum 27 and the triple thread screw 28. Is moved in the advance direction (right direction in FIG. 2).

Depending on the position of the intermediate gear 23 in the axial direction, the relative phase of the rotators 21 and 22 changes, and the phase of the intake camshaft 134 with respect to the crankshaft 120 changes.
The electric actuator 17 and the electromagnetic retarder 24 are driven and controlled according to the operating state of the engine by a control signal from the ECU 114.
The variable valve timing mechanism VTC 113 is not limited to the structure shown in FIG. 2, and all known variable valve timing mechanisms can be applied.

The ECU 114 has a built-in microcomputer and controls the electronic control throttle 104, the variable valve timing mechanism VTC 113, the fuel injection valve 131, and the like by arithmetic processing based on detection signals from various sensors.
Examples of the various sensors include an accelerator opening sensor 116 that detects the accelerator opening, an air flow meter 115 that detects the intake air amount Q of the engine 101, a crank angle sensor 117 that detects the rotational position of the crankshaft 120, and a throttle valve 103b. A throttle sensor 118 that detects the opening degree TVO, a water temperature sensor 119 that detects the coolant temperature of the engine 101, and a cam sensor 132 that detects the rotational position of the intake camshaft 134 are provided.

The crank angle sensor 117 detects a detected portion of a signal plate pivotally supported on the crankshaft 120, and as shown in FIG. 3, a pulse signal that rises at every crank angle of 10 deg from the top dead center of each cylinder. The unit crank angle signal POS is output.
Here, the unit crank angle signal POS is set so as to be missing at the rotational positions 60 deg and 70 deg before the top dead center of each cylinder.

Further, the cam sensor 132 detects the detected portion of the signal plate that is pivotally supported on the intake side camshaft 134, so that as shown in FIG. 3, every crank angle 180 deg corresponding to the stroke phase difference between the cylinders, A cam signal CAM indicating the compression top dead center cylinder by the number of pulses is output.
FIG. 3 shows a state where the phase of the camshaft 134 is controlled to the most retarded angle by the variable valve timing mechanism VTC113.

The ignition in the present embodiment is performed in the order of # 1 cylinder → # 3 cylinder → # 4 cylinder → # 2 cylinder. For example, when three pulse signals are continuously output as the cam signal CAM, the compression is next performed. The cylinder that is the dead center is determined to be the # 4 cylinder.
The ECU 114 measures the generation cycle of the unit crank angle signal POS to detect the unit crank angle signal POS output at the position of BTDC 50 deg immediately after the tooth missing, and three unit crank angle signals POS are input. The value of the counter CRACNT1 counted up every time is cleared at the position of BTDC 50deg.

Further, the value of the counter CRACNT2, which is counted up every time three unit crank angle signals POS are input, is cleared every time the value of the counter CRACNT1 becomes 4.
The number of occurrences of the cam signal CAM is counted during the period in which the counter CRACCNT2 is cleared, that is, from BTDC 110deg to the next BTDC 110deg, and the top dead center position included in the next one cycle It is discriminated whether the compression top dead center is present, and the cylinder discrimination value CTYLCNT is updated and set.

  In the control of the fuel injection timing and ignition timing of each cylinder, the cylinder for performing fuel injection / ignition is specified based on the cylinder discrimination value CTYLCNT, and the required fuel injection timing / ignition timing is set to the unit crank angle signal POS. Is detected by counting the unit crank angle signal POS from the unit crank angle signal POS as a control reference detected based on the tooth missing position and time conversion of an angle of 10 deg or less, and injects fuel into the fuel injection valve 131 of the cylinder to be injected. An injection pulse signal is output, and an ignition control signal is output to a power transistor that controls energization of an ignition coil of a cylinder to be ignited.

  Further, the rotational phase of the camshaft 134 with respect to the crankshaft 120 is detected as an angle from the control reference detected based on the tooth missing position of the unit crank angle signal POS to the leading cam signal CAM. The variable valve timing mechanism VTC 113 is feedback-controlled so that the detected rotation phase becomes a target value corresponding to the engine operating state.

  Further, when the crank angle sensor 117 fails, the variable valve timing mechanism VTC 113 is returned to the default position where the phase of the camshaft 134 is the most retarded angle, while the generation period of the cam signal CAM is measured, whereby BTDC 50 deg. Is determined from the number of cam signals CAM following the head signal, and further, the fuel injection timing and ignition timing are detected by measuring the time based on the head signal. (See FIG. 4).

By the way, the position where the cam signal CAM is generated from the cam sensor 132 varies depending on the extension of the timing chain, etc., so that the fuel injection timing / ignition timing (engine) detected based on the cam signal CAM when the crank angle sensor 117 fails. There is a possibility that an error occurs in the control timing and the operability of the engine is greatly deteriorated.
Therefore, in this embodiment, when the crank angle sensor 117 is normal, the variation in the output position of the cam signal CAM is learned in advance, and when the crank angle sensor 117 fails, the fuel is calculated based on the learned variation. The detection of the injection timing / ignition timing (engine control timing) is corrected.

FIG. 5 is a flowchart showing the variation learning.
In the flowchart of FIG. 5, in step S1, failure diagnosis of the crank angle sensor 117 is performed.
In the failure diagnosis, for example, when it is determined that the engine is rotating due to the generation of the cam signal CAM, the failure of the crank angle sensor 117 is determined when the unit crank angle signal POS is not output.

In the next step S2, it is determined whether or not the crank angle sensor 117 is diagnosed as normal in the failure diagnosis in step S1.
When the crank angle sensor 117 (and the cam sensor 132) is normal, the process proceeds to step S3.
In step S3, in order to learn variation in the output position of the cam signal CAM, the variable valve timing mechanism VTC113 is temporarily controlled to the most retarded position (stopper abutting position).

In step S4, it is determined whether or not a learning permission condition is satisfied.
As the learning permission condition, a predetermined time has passed since the variable valve timing mechanism VTC113 was controlled to the most retarded position, a normal determination was made by a failure diagnosis of the variable valve timing mechanism VTC113, an engine The cooling water temperature (engine temperature) is at least a predetermined temperature or higher.

The condition for the passage of time from the control to the most retarded angle position is to cope with the response delay of the variable valve timing mechanism VTC113, and the normal condition avoids learning in a state where the valve is advanced by a failure. Therefore, the temperature condition is a condition for performing learning in a state where the phase shift between the crankshaft and the camshaft is stable.
If it is determined in step S4 that the learning permission condition is satisfied, the process proceeds to step S5.

In step S5, the phase angle CAMANGn (n is a cylinder number) of the cam signal CAM is detected.
As shown in FIG. 3, the phase angle CAMANGn of the cam signal CAM is from the position of BTDC 110 deg (the generation position of the unit crank angle signal POS immediately after tooth missing) from the position of the counter CRACCNT2 to the head cam signal CAM. Is an angle.

The phase angle CAMANGn is measured for each cylinder as the value of the counter CRACNT2 and the time TCAM (see FIG. 6) from the update timing of the counter CRACNT2 to the start cam signal CAM immediately before the output timing of the start cam signal CAM. The
The time TCAM is converted into an angle based on the update cycle TCRA30 of the counter CRACNT2.

That is, the phase angle CAMANGn is
CAMANGn = (CRACNT2 + TCAM / TCRA30) × 30
As required.
When the phase angle CAMANGn of the cam signal CAM is detected in step S5, in the next step S6, the variation learning value KOFSTn (n is the cylinder number) of the cam signal CAM set for each cylinder is updated according to the following equation.

KOFSTn = ((60−CAMANGn) × (1−K)) + KOFSTn−1 × K
In the above equation, 60 is a reference value of the phase angle CAMANG, KOFSTn−1 is the previous value of the learning value KOFSTn, and K is a weighting coefficient where 0 <K <1.
According to the above formula, if the previous value of the learning value KOFSTn and the phase variation of the latest detected cam signal CAM are weighted and averaged to update KOFSTn, for example, even if noise is superimposed on the cam signal CAM, It is possible to avoid the learning value KOFSTn from fluctuating greatly due to the influence, and the reliability of the learning value KOFSTn can be improved.

On the other hand, if it is determined in step S2 that the failure of the crank angle sensor 117 has been diagnosed, the process proceeds to step S7.
In step S7, the engine control timing is detected based on the cam signal CAM and the engine is operated. Here, the detection of the engine control timing is corrected based on the learning value KOFSTn.

For example, when the ignition timing is detected based on the cam signal CAM and the ignition advance value is 20 deg, the angle FIG. N (deg) up to the ignition timing is calculated based on the leading cam signal CAM as shown in FIG. .
FIG (deg) = 50 deg−20 deg (ignition advance value) + KOFSTn
In the above equation, 50 deg is an angle from the top dead center TDC to the immediately preceding leading cam signal CAM, and the angle FIGN (deg) is an angle from the leading cam signal CAM to the ignition timing.

Here, the position where the leading cam signal CAM is actually output from BTDC 50 deg is corrected by correcting the angle FIGN (deg) up to the ignition timing based on the learned value KOFSTn learned when the crank angle sensor 117 is normal. Even if it deviates, a desired ignition timing can be detected with high accuracy.
The angle FIGN (deg) is converted into time TIGN based on the cycle TNE of the leading cam signal CAM, and the time point when the time TIGN has elapsed from the leading cam signal CAM is detected as the ignition timing.

TIGN = FIGN × TIDG (TIDG = TNE / 180)
In this embodiment, the variation in the output position of the cam signal CAM is learned for each cylinder (for each head cam signal CAM). However, the variation may be learned as a value common to all the cylinders. If it is a type | mold engine, it can be made to learn for every bank and can also be set as the structure made to learn for every cylinder group which performs synchronous control, such as simultaneous injection.

Further, the control accuracy of the rotational phase can be improved by correcting the detection result of the rotational phase of the camshaft 134 by the learned value KOFSTn.
Here, technical ideas other than the claims that can be grasped from the above embodiment will be described together with effects.
(A) In the control device for an internal combustion engine according to any one of claims 1 to 3,
The cam signal is output at least for each stroke phase difference between the cylinders, and the cam signal for each stroke phase difference is associated with each cylinder.
The control apparatus for an internal combustion engine, wherein the variation learning of the output position is performed for each cylinder, for each bank of a multi-bank engine, or for each cylinder group performing synchronous control.

According to such a configuration, whether to learn variation for each cam signal corresponding to each cylinder, or to learn variation for each bank (for each camshaft) in the case of a multi-bank engine such as a V-type engine, The variation is learned for each cylinder group that performs synchronous control such as fuel supply at the same time.
Therefore, in the learning for each cylinder, the detection variation in the control timing can be corrected for each cylinder. In the learning for each bank, the detection variation in the control timing can be corrected for each cam sensor provided in the camshaft of each bank. In learning for each cylinder group that performs synchronous control, the control timing detection variation is corrected for each cylinder by correcting the control timing detection variation for each cylinder group.
(B) In the control device for an internal combustion engine according to any one of claims 1 to 3,
The control apparatus for an internal combustion engine, wherein the learning value is updated by weighting the latest detection result of the variation in the output position and the learning value until the previous time in the learning of the variation in the output position.

According to such a configuration, the latest detection result of the variation in the output position of the cam signal is not reflected in the correction of the engine control timing as it is, but the learning value is weighted to the previous learning value and the latest variation detection result. Update the engine control timing based on the cam signal based on the updated learning value.
Therefore, even if the variation detection result becomes temporarily abnormal due to noise superimposition, etc., this abnormal detection result is not used as it is for correcting the engine control timing, improving the reliability and stability of the correction process. Can be made.

The block diagram of the internal combustion engine in embodiment. Sectional drawing of the variable valve timing mechanism in embodiment. 6 is a time chart showing the characteristics of the counters of the unit crank angle signal POS, cam signal CAM, and unit crank angle signal POS in the embodiment. The time chart for demonstrating the detection of the ignition timing at the time of the crank angle sensor failure in embodiment. 5 is a flowchart showing variation learning of the output position of the cam signal CAM in the embodiment. The time chart which shows the detection of the output position of the cam signal CAM in embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 101 ... Internal combustion engine, 105 ... Intake valve, 113 ... Variable valve timing mechanism VTC, 114 ... Engine control unit, 117 ... Crank angle sensor, 120 ... Crankshaft, 132 ... Cam sensor, 134 ... Camshaft

Claims (3)

A crank angle sensor that outputs a crank angle signal for each predetermined rotation position of the crankshaft, and a cam sensor that generates a cam signal for each predetermined rotation position of the camshaft,
Perform a failure diagnosis of the crank angle sensor,
When the crank angle sensor is normal, the engine control timing is detected based on the crank angle signal, and when the crank angle sensor is faulty, the engine control timing is detected based on the cam signal.
When the crank angle sensor is normal, the variation in the output position of the cam signal is learned with reference to the crank angle signal,
A control apparatus for an internal combustion engine that corrects detection of engine control timing based on the cam signal in accordance with a variation in the output position of the learned cam signal when the crank angle sensor fails. A variable valve timing mechanism that varies the valve timing of the engine valve by changing the rotational phase of the camshaft relative to the crankshaft;
2. The control apparatus for an internal combustion engine according to claim 1, wherein the variation learning of the output position of the cam signal is performed in a state where the variable valve timing mechanism is controlled to the most retarded angle side.   3. The control apparatus for an internal combustion engine according to claim 1, wherein the variation learning of the output position of the cam signal is performed in a state where the engine is completely warmed.

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