JPH1182145A - Crank angle detecting device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To measure a crank angle with accuracy on the basis of position signals outputted every 10 deg. and a specified angle position being missing. SOLUTION: At the time of detecting a specified crank angle from a measuring reference position, in case a position part is not included in a measuring block (3), the angle is measured by counting position signals POS by the number corresponding to the measured angle. In case the missing part is positioned at the end of the measuring block (2), the position signal outputted immediately before the missing part is counted the and part and the angle part of a fraction are measured by measuring time on the basis of the position signal outputted immediately before the missing part. In case the missing part is positioned between the position signals POS in the measuring block, the angle is measured by counting the position signals POS in the number less by one than the count number corresponding to the measured angle.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a crank angle detecting device for an internal combustion engine, for example, for detecting a crank angle from a reference position for controlling the energization of an ignition coil and controlling the injection timing of a fuel injection valve. About technology.

[0002]

2. Description of the Related Art Conventionally, a crank angle from a measurement reference position to a start time of energization to an ignition coil, a stop time of energization (ignition timing), or a start time of fuel injection is output from a crank angle sensor for each unit crank angle. The detection is performed by counting the position signal to be performed.

The position signal is normally output at every 1 °, a reference signal is output at a reference crank angle position, and the energization control timing is counted by counting the position signal using the reference signal as a measurement reference. And the crank angle until the injection start timing is detected.

[0004]

However, if the sensor outputs the reference signal together with the position signal for each 1 ° as described above, it is necessary to form the detected portion of the sensor for every 1 °. In addition, two systems of sensors are required to output the position signal and the reference signal independently, and there is a problem that the cost of the crank angle sensor increases.

Accordingly, the present applicant has proposed a configuration in which the position signal is output at every 10 ° CA, for example, to reduce the number of detected parts, and the position signal at every 10 ° CA indicates that the position signal is missing at a predetermined angular position. The reference signal is generated in a pseudo manner based on the missing portion, and the cost of the crank angle sensor is reduced.

However, when the crank angle is measured by counting the number of position signals generated, for example, since the required ignition timing changes in a relatively wide range, the missing portion is included in the crank angle measurement section. In some cases, simply counting the position signal causes an error in the measurement of the crank angle.

Accordingly, an object of the present invention is to make it possible to accurately detect a crank angle by counting position signals having missing teeth.

[0008]

According to a first aspect of the present invention, there is provided a crank angle sensor configured such that a position signal output for each unit crank angle causes a missing tooth at a predetermined angular position. The relative position of the missing portion with respect to the crank angle measurement section is calculated in advance, and the crank angle measurement process using the count result of the position signal is changed based on the calculation result.

With this configuration, it is determined whether or not the position signal includes a missing portion in the measurement section, and if the missing portion is included, which position in the measurement section corresponds to the position signal. The processing method for detecting the crank angle by counting the position signal based on these pieces of information in advance and changing the processing method is changed to eliminate the influence of the missing tooth. According to the second aspect of the invention, the reference position for measuring the crank angle is fixed, and the relative position is detected in advance based on the result of dividing the measured angle by the unit crank angle.

With this configuration, if the measurement reference position is fixed, the angle from the measurement reference position to the missing portion is also fixed, and the angle can be specified as a multiple of the unit crank angle + α. Similarly, by comparing the measurement angle with the result obtained by dividing the measured angle by the unit crank angle,
It is possible to determine the relative position of the missing portion in the measurement section.

According to a third aspect of the present invention, a reference signal is artificially generated by counting the position signal with reference to the missing portion, and the crank angle is measured using the reference signal as a measurement reference. . According to this configuration, when the missing portion is detected based on, for example, the interval of generation of the position signal, the position where the position signal is counted by a predetermined number from the missing portion is detected as the reference signal generation position, and directly. A reference signal is artificially generated without detecting the reference angle position, and the position of the predetermined crank angle is measured from the reference signal using the reference signal as a measurement reference.

[0012] In the invention described in claim 4, when the missing portion is included in the measurement section, the count value of the position signal is corrected to detect a crank angle, and the missing portion includes the missing portion. When located at the end of the measurement section, the interval between the position signal output immediately before the missing portion and the missing portion is converted into time and measured.

According to this configuration, when a missing portion is included in the measurement section, the count-up of the position signal is not originally performed in the missing portion. Since an error corresponding to the position signal generation interval is generated, the target value in the count processing is reduced or changed, or the count result is raised to prevent the count from being increased at the missing portion. In addition, if the missing portion is located at the end of the measurement section, the angle measurement by counting the position signal can be performed only up to the position signal immediately before the missing portion. The angle is detected by measuring the corresponding time.

According to the present invention, the unit crank angle is larger than the minimum unit angle in setting the measurement angle, and the crank angle is measured by counting the position signal and the fractional angle smaller than the unit crank angle. When the missing portion is located at the end of the measurement section, the total sum of the unit crank angle and the fractional angle is converted to time, and immediately before the missing portion. The end point of the measurement section is detected by measuring the time based on the position signal output to the control unit.

According to this configuration, when the end point of the measurement section is located between the position signals, the angle measurement by counting the position signals cannot be performed up to the position signal output immediately before the end point. The angle from the immediately preceding position signal to the end point is converted into time, and the fractional angle is detected by measuring the time.
If the missing portion is located at the end of the measurement section, as described above, the time measurement reference needs to be the position signal output immediately before the missing portion, so that the angle to be converted into time and measured Is the sum of the angle from the position signal immediately before the missing portion to the missing portion and the fractional angle from the missing portion to the end point.

[0016]

According to the first aspect of the present invention, when the crank angle is measured based on the count of the position signal, the relative position between the position where the position signal is missing and the measurement section is obtained in advance. In addition, even if the measurement section fluctuates, it is possible to prevent an angle measurement error from occurring due to a missing position signal.

According to the second aspect of the present invention, if the reference position for angle measurement is fixed, the relative position between the measurement section and the missing portion is determined based on the result obtained by dividing the measurement angle by the position signal generation interval angle. Can be easily detected. According to the third aspect of the present invention, the reference signal can be artificially generated based on the portion where the position signal is missing, and the measurement of the crank angle based on the fixed measurement reference position (reference position) is performed by the reference. This has the effect of realizing it without using a sensor for generating a signal.

According to the fourth aspect of the present invention, it is possible to measure the desired crank angle in response to the fact that the position signal is not counted up at the portion where the tooth is missing. In the case where the missing portion is located, the angle of the missing portion where the position signal is not counted up can be measured based on the time measurement based on the position signal output immediately before the missing portion. is there.

According to the fifth aspect of the invention, even if the position signal generation interval angle is made larger than the minimum unit angle of the measurement angle to simplify the sensor configuration, the counting of the position signals is sufficient. There is an effect that the crank angle can be detected with high accuracy.

[0020]

Embodiments of the present invention will be described below. FIG. 1 is a diagram showing an internal combustion engine according to an embodiment. The engine 1 shown in this figure is a direct injection type spark ignition gasoline engine, as described later. However, the engine is not limited to the direct injection type gasoline engine, but may be an engine that performs port injection.

In the engine 1, the air that has passed through the air cleaner 2 is measured by a throttle valve 3 and is sucked into a cylinder via an intake valve 4. The electromagnetic fuel injection valve 5 is configured to inject fuel (gasoline) directly into the combustion chamber, and a fuel-air mixture is formed in the cylinder by the fuel injected from the fuel injection valve 5.

The air-fuel mixture is ignited and burned by spark ignition by a spark plug 6, and the combustion exhaust gas is discharged from the cylinder via an exhaust valve 7, purified by a catalyst 8, and released to the atmosphere. A control unit 10 incorporating a microcomputer controls fuel injection by the fuel injection valve 5 and ignition by a spark plug 6 (energization of an ignition coil (not shown)).
10 receives signals from various sensors.

As the various sensors, an air flow meter 11 for detecting an intake air flow rate Q of the engine 1 and a crank angle of 10 °
Crank angle sensor that outputs position signal POS every time
12, an oxygen sensor 15 for detecting the air-fuel ratio of the combustion mixture in response to the oxygen concentration in the exhaust gas, and an opening TV of the throttle valve 3
A throttle sensor 16 for detecting O, a water temperature sensor 17 for detecting a cooling water temperature Tw, and the like are provided.

The crank angle sensor 12 outputs a position signal POS at every 10 ° crank angle with respect to TDC. As shown in FIG. 2, the position signal POS becomes missing at a BTDC of 60 °. Is configured. This is because if the position signal POS is output every 10 ° over the entire range of the crank angle,
Since a separate sensor for detecting the piston position (reference angle) is required, a missing portion is intentionally provided, and the piston position (reference angle) can be detected based on the missing portion. Things.

When the control unit 10 detects a missing portion on the basis of the generation cycle of the position signal POS, the control unit 10 counts the position signal POS thereafter, and when the count value matches a value stored in advance, A reference signal REF is artificially generated. The pseudo reference signal REF is used as a reference for measuring the ignition timing and the fuel injection timing as described later, and is generated at a position of BTDC110 ° in the present embodiment.

As described above, in this embodiment, since a reference signal (reference angle signal) REF is generated in a pseudo manner, no sensor for outputting a reference signal is provided. In the engine 1, a homogeneous combustion system in which fuel is injected during an intake stroke to form a homogeneous air-fuel mixture in a cylinder to perform homogeneous combustion, and ignition is performed by performing fuel injection during a compression stroke. A stratified combustion system in which a rich air-fuel mixture is formed around the plug 6 to perform stratified combustion can be switched. The control unit 10 determines a target equivalent ratio and a combustion system according to operating conditions. The fuel injection amount and the injection timing of the fuel injection valve 5 are set accordingly, and the ignition timing (ignition advance) of the ignition plug 6 is referred to by referring to the ignition timing map individually set for each combustion method. Angle value).

Here, the control of the ignition timing by the control unit 10, more specifically, the manner of controlling the energization of the ignition coil (primary side) will be described with reference to the time chart of FIG. 2 and the flowchart of FIG. The flowchart of FIG. 3 is executed by interrupting at the previous ignition timing and setting and measuring an angle (non-energization angle) from the previous ignition timing to the start of energization to the ignition coil.

First, in step 1 (indicated as S1 in the figure, the same applies hereinafter), the required energization time TDWLL is set based on the battery voltage and the like. In the next step 2, the energization time TDWLL is converted into an energization angle DWLL based on the engine speed Ne at that time. In step 3, it is determined whether the cylinder to be ignited next time is homogeneous combustion or stratified combustion.

If it is determined in step 3 that stratified combustion is to be performed in the next ignition cylinder, the process proceeds to step 4,
From an ignition timing map previously matched for stratified combustion, an ignition timing AD suitable for the engine load and rotation at that time
VS (ignition advance value) is retrieved and set as ignition timing ADV. On the other hand, if it is determined in step 3 that homogeneous combustion is to be performed in the next ignition cylinder, the process proceeds to step 5 and matches the engine load and rotation at that time from the ignition timing map previously matched for homogeneous combustion. The ignition timing ADVH (ignition advance value) is searched, and the ignition timing A
Set to DV.

In step 6, the non-energizing angle NDWLL at which the energizing angle DWLL is obtained when the energizing of the ignition coil is cut off based on the next ignition timing ADV is calculated according to the following equation. NDWLL = 720 ° / NCYL−DWLL + (ADV ₋₁
−ADV) The NCYL is the number of cylinders, and the stroke phase difference between the cylinders is calculated by 720 ° / NCYL.
Non-energization angle NDWLL in the case where ignition timing is not changed by DWLL and ignition is performed at intervals matching the stroke phase difference
(The basic value of the non-energization angle) is calculated.

However, in practice, the ignition timing may change stepwise due to the switching of the combustion method. Therefore, the deviation between the previous ignition timing ADV- ₁ and the next ignition timing ADV is calculated by the basic value of the non-energization. In the case where the ignition timing (energization cutoff timing) greatly changes due to the switching of the combustion method, the basic value of the non-energization angle is corrected to be reduced by the advancement change of the ignition timing so that the energization start is advanced. To Conversely, when the ignition timing changes in retard, the basic value of the non-energization angle is corrected to increase by the amount of the retard change in ignition timing to delay the start of energization.

In step 7, the number of position signals POS from the previous ignition timing until the position signal POS becomes missing is calculated. The missing part is BTD in advance
It is known that the position is C60 °, and the position of the position signal POS output immediately after the previous ignition timing is known based on the previous ignition timing. The number of position signals POS to be counted up to the position (the number from the previous ignition timing to the position signal output immediately before tooth loss) can be calculated.

In step 8, the number of position POS A from the previous ignition timing to the missing tooth obtained in step 7 and
The non-energizing angle ND is determined based on the number of position POS B that is counted when there is no missing tooth from the previous ignition timing to the end point of the non-energizing angle NDWLL.
It is determined whether or not the missing portion is located last in the WLL, that is, the end point of the non-energization angle NDWLL is BTDC.
It is determined whether or not it exceeds 60 ° and is before BTDC 50 °.

The number B of the position POS is an angle CAH from the previous ignition timing to the position signal POS immediately after.
In this case, the quotient obtained when the calculation of (NDWLL-CAH) / 10 ° is performed (the remainder at this time is α) is obtained. And the position POS number A
When +1 is equal to the number B of the position POS, it is determined that the end point of the non-energization angle NDWLL is over BTDC60 ° and before BTDC50 °.

At this time, if the position signal POS is counted on the premise that the position signal POS is generated even at the BTDC 60 °, the position signal POS actually output at the BTDC 50 ° past the end point position is obtained.
Is specified as a signal immediately before the end point.
Therefore, when it is determined that the end point of the non-energization angle NDWLL exceeds BTDC60 ° and is before BTDC50 °, the process proceeds to step 9 and the position signal output last within the non-energization angle NDWLL (in the measurement section). As the POS, the target of the count value is determined as (B-1) so that the position signal POS output at BTDC 70 ° is detected, and the end point of the non-energization angle NDWLL is determined from the position signal POS output at BTDC 70 °. Convert the angle to the position (= 10 ° + α: α <10 °) into time, BT
It is set so that the time point when the time has elapsed from DC 70 ° is detected as the end point position.

On the other hand, if it is determined that the missing portion is not located at the end of the non-energization angle NDWLL, the process proceeds to step 10, where
It is determined whether or not the missing portion is positioned between the positioning signals POS based on whether or not A + 1 <B. If the missing portion is located between the position signals POS within the non-energization angle NDWLL, the fractional angle α of less than 10 ° is time-measured with reference to the position signal POS output immediately before the end point. Should do,
The position signal P
An error occurs in the angle measured based on the count value of the OS, and as a result, the position signal POS for performing the time measurement for the fractional angle α becomes the position signal POS which is one position after the request. .

Therefore, in this case, the process proceeds to step 11, in which the count result of the position signal POS is increased by one or the target count value is decreased by one, and the position signal POS is corrected at BTDC 60 °. Even if it is not output, the desired angle can be correctly measured from the count value of the position signal POS. If the missing portion is not included in the measurement section within the non-energization angle NDWLL (A ≧ B), the process proceeds to step 12, and the position signal POS output immediately before the end point position is changed to the count value. Detection is performed based on the count result of the position signal POS without correction, and a time corresponding to a fractional angle is measured from the immediately preceding position signal POS to detect the end point position.

When the non-energization angle NDWLL is measured as described above, the energization of the ignition coil is started. The timing (ignition timing) at which the energization of the ignition coil is cut off to perform ignition is determined by the ignition advance. The ignition timing given as the angle value is converted into an angle FADV from the pseudo reference signal REF to the ignition timing. And the non-energization angle ND
Similarly to WLL, the relative position of the tooth missing portion with respect to the measurement section of the angle FADV is determined, and the count processing of the position signal POS and the time measurement processing of the fractional angle are changed based on the determination result, and the pseudo reference signal REF is changed. Then, the time when the motor is rotated by the angle FADV is measured, and the power supply to the ignition coil is cut off.

As shown in FIG. 4, when the injection start timing is measured based on the pseudo reference signal REF, the angle ANGTMS from the pseudo reference signal REF to the injection start timing is set in the same manner as the non-conduction angle NDWLL. Can be measured. However, the angle (FADV, ANGT) based on the pseudo reference signal REF
In the measurement of (MS), the relative position between the pseudo reference signal REF, which is the measurement reference, and the missing portion is fixed.
The quotient (POS count value) obtained by dividing the measured angle by 10 ° which is the interval (unit crank angle) of the position signal POS, and the number of positions from the previously stored pseudo reference signal REF to the missing position ( In the case of FIG. 4, the relative position between the measurement section and the missing portion can be known from 4), and the setting for switching the angle measurement method can be made.

In the example shown in FIG. 4, the pseudo reference signal REF is generated at the position of BTDC 110 °, and the missing of the position signal POS occurs at the position of BTDC 60 °. When it is less than 4, the missing section is not included in the measurement section, and when the quotient (count value) is 5, the missing section is located at the end of the measurement section, and the quotient ( When the (count value) is 6 or more, the missing portion is located between the position signals POS in the measurement section.

For example, when the angle ANGTMS is 75 ° (case (1) of FIG. 4), ANGTMS = 75 ° = POS × 7 count + 5, which is sandwiched by the position signal POS in the measurement section. As a result, the position signal is counted six times from the pseudo reference signal REF.
The point in time at which a time corresponding to 5 ° has elapsed from the second position signal POS may be detected as the injection timing.

When the angle ANGTMS is 56 ° (case (2) in FIG. 4), ANGTMS = 56 ° = POS × 5 count + 6, and a missing portion at the end of the measurement section. Therefore, the position signal is counted four times from the pseudo reference signal REF, and the fourth position signal POS is counted.
Then, the time point at which a time corresponding to 10 ° + 6 ° = 16 ° elapses may be detected as the injection timing.

Further, when the angle ANGTMS is 35 ° (case (3) of FIG. 4), ANGTMS = 35 ° = POS × 3 count + 5, and the missing section is included in the measurement section. Therefore, the position signal is counted three times as it is from the pseudo reference signal REF, and the third position signal P
The time point at which a time corresponding to 5 ° has elapsed from the OS may be detected as the injection timing.

Incidentally, instead of decreasing the target count value of the position signal POS, the count result of the position signal POS may be increased in advance.

[Brief description of the drawings]

FIG. 1 is a diagram showing a system configuration of an internal combustion engine according to an embodiment.

FIG. 2 is a time chart showing a state of energization control of an ignition coil in the embodiment.

FIG. 3 is a flowchart showing a state of non-energization angle control in the embodiment.

FIG. 4 is a time chart showing an aspect of injection timing control in the embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Internal combustion engine 3 Throttle valve 4 Intake valve 5 Fuel injection valve 6 Spark plug 7 Exhaust valve 10 Control unit 11 Air flow meter 12 Crank angle sensor

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Taku Oba Nissan Motor Co., Ltd., 2 Takaracho, Kanagawa-ku, Yokohama-shi, Kanagawa

Claims (5)

[Claims] A crank angle sensor configured to cause a position signal output for each unit crank angle to cause tooth loss at a predetermined angular position, wherein a relative position of the tooth loss portion with respect to a crank angle measurement section. A crank angle detection device for an internal combustion engine, wherein a position is calculated in advance, and a crank angle measurement process using a count result of the position signal is changed based on the calculation result. 2. A crank angle measurement reference position is fixed.
The crank angle detecting device for an internal combustion engine according to claim 1, wherein the relative position is detected in advance based on a result obtained by dividing a measured angle by the unit crank angle. 3. The method according to claim 2, wherein a reference signal is artificially generated by counting the position signal based on the missing portion, and the crank angle is measured using the reference signal as a measurement reference. Crank angle detection device for an internal combustion engine. 4. When the missing portion is included in the measurement section, the count value of the position signal is corrected to detect a crank angle, and the missing portion is located at the end of the measurement section. The internal combustion engine according to any one of claims 1 to 3, wherein when performing the measurement, the time between the position signal output immediately before the missing portion and the missing portion is converted into time and measured. Engine crank angle detector. 5. The method according to claim 1, wherein the unit crank angle is larger than a minimum unit angle in setting the measurement angle.
The position signal is counted, and the time is measured by measuring a fractional angle less than the unit crank angle.When the tooth missing portion is located at the end of the measurement section, the unit crank angle and the angle of the fraction are set. 5. The internal combustion engine according to claim 4, wherein the sum of the values is converted into a time, and the end point of the measurement section is detected by measuring the time based on a position signal output immediately before the tooth missing portion. Crank angle detection device.