JPH0283452A - Optical crank angle sensor response delay correction device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a response delay correction device for an optical crank angle sensor, and more specifically, the present invention relates to a response delay correction device for an optical crank angle sensor. The present invention relates to a technology for improving the accuracy of detecting the crank angle position of an internal combustion engine.

<Conventional technology> Conventionally, internal combustion engine rotational speed N detection and ignition timing ADV
An optical crank angle sensor is used for control purposes (see Japanese Patent Laid-Open No. 59-49369, etc.).

Such an optical crank angle sensor is provided with a signal disk plate that rotates in conjunction with engine rotation, and a slit is formed through the signal disk plate at a predetermined position on the circumference, and light passing through the slit is transferred to a phototransistor. By detecting this, a pulse signal that rises at a predetermined crank angle position (reference crank angle position it) is obtained.

For example, in the case of a four-cylinder internal combustion engine, a slit is formed so that a detection signal is output every 180 degrees of the crank angle, and the large pulse signal every 180 degrees of the crank angle is used as the reference crank angle signal Ref to control the ignition timing. ADV and engine rotational speed N are detected. That is, as shown in FIG. 6, for example, the rising edge of a pulse signal that rises at a predetermined crank angle position is detected, and the engine rotational speed N is calculated from the interval time TRef at which this rising edge is detected.
The crank angle from the rising timing to the desired ignition timing ADV is converted into time based on the detected value of the engine rotation speed N, and the time ADVT from when the rising edge of the pulse signal is detected to the ignition timing ADV is measured to ignite. I am trying to get them to do this.

The engine rotation speed N may also be calculated by detecting the rise and fall of a pulse signal output from the crank angle sensor and measuring the pulse width time TRefH corresponding to a predetermined crank angle.

<Problem to be solved by the invention> As described above, conventionally, the rise of the pulse signal output from the optical crank angle sensor is used as the measurement reference point for various controls, but in order to reduce costs, it is necessary to compare the rise responsiveness. When an inexpensive phototransistor is used, the true rise timing cannot be detected if the configuration is such that the rise of the pulse signal is determined when the pulse signal crosses a predetermined slice level, as shown in FIG. figure,
There is a problem in that it is not possible to accurately detect the desired crank angle '1 position, which is the light reception start position of the phototransistor defined by the opening position of the slit.

In this way, if a position deviated from the expected crank angle position is incorrectly determined to be the reference crank angle position, for example, if the ignition timing ADV @ is measured from the reference crank angle position, the ignition timing will be changed by the response delay time of the phototransistor. As shown in Figure 8, ADV will be delayed, especially in the high rotation range where the rotation angle per unit time is large.
Even if the detection error time of the ignition timing ADV due to the response delay time is small, the actual ignition angle will deviate greatly.

In addition, when detecting the engine rotation speed N by measuring the pulse width of the pulse signal output from the optical crank angle sensor (a value equivalent to a predetermined crank angle defined by the slit width), the above-mentioned method is used. Since the detection time is set to be shorter than the actual time due to the rise response delay time of the phototransistor, a problem arises in that the engine rotational speed N is erroneously detected as being higher than the actual value.

The present invention was made in view of the above problems, and even if the phototransistor has a response delay time of rising,
It is an object of the present invention to provide a response delay correction device that can perform accurate control based on the rise timing of a pulse signal from an optical crank angle sensor.

Means for Solving the Problems> Therefore, in the present invention, as shown in FIG. In an optical crank angle sensor that detects light from a light source passing through a slit with a phototransistor and outputs a pulse signal with a period synchronized with engine rotation, the rising edge of the pulse signal is detected by comparing it with a predetermined slice level. A response device comprising: a rise detection means; and a reference time setting means for correcting the rise time detected by the rise detection means based on a predetermined response delay time of the phototransistor and setting the corrected rise time as a reference rise time. A delay correction device was configured.

Effect> If the phototransistor constituting the crank angle sensor has a delay time in its rise response as shown in FIG. 7, this delay time will be a substantially constant time regardless of the engine rotation speed. Therefore, by measuring this response delay time in advance and comparing it with the slice level, the rise time of the pulse signal obtained is the time when this delay time has elapsed from the crank angle position desired to be detected (the true rise time). It is constructed so that it is assumed that there is.

That is, when a rising edge of a pulse signal is detected by comparison with the slice level, this rising timing is corrected by a predetermined response delay time of the phototransistor, the true rising timing is calculated backwards, and this corrected rising timing is used as the reference rising timing. For example, this is the starting point of time measurement in ignition timing control.

<Example> The present invention will be explained in detail below.

In FIG. 2, the intake passage 2- of the engine 1 is provided with an air flow meter 3 that detects the intake air flow rate Q, and an idle switch 5 that is turned ON when the throttle valve 4 is in the fully closed position (idle position). These detection signals are input to a control unit 6 containing a microcomputer. Further, the engine 1 is provided with an electromagnetic fuel injection valve 7 for each cylinder. These fuel injection valves 7 are driven to open and open in an on/off manner by a drive pulse signal outputted from the control unit 6 in accordance with the calculated fuel injection amount Ti, and inject and supply fuel to the engine 1.

Further, each cylinder of the engine 1 is provided with an ignition plug 8.

A high voltage generated by an ignition coil 9 is sequentially applied to these ignition plugs 8 via a distributor 1O, thereby igniting a spark to ignite and burn the air-fuel mixture. here,
The ignition coil 9 has a power transistor 1 attached thereto.
1, the timing of high voltage generation is controlled. The ignition timing ADV is controlled by controlling the ON/OFF timing of the power transistor 11 using an ignition signal from the control unit 6.

An optical crank angle sensor 12 is built into the distributor IO. The crank angle sensor 12 includes a signal disk plate 14 that rotates together with the distributor shaft 13 and a component 15. The signal disc plate 14 has 4
In the case of a cylinder, the four slits for the reference signal Ref are 90
° The milk is formed through the intervals.

The detection unit 15 is composed of a light emitting diode, a phototransistor, etc. (not shown), and detects the light from the light emitting diode as a light source that passes through the slit 17 with the phototransistor, and detects the predetermined reference crank angle position where the slit 17 is formed. It outputs a pulse signal having a width equivalent to a predetermined crank angle that rises at every 180° crank angle, and this pulse signal synchronized with engine rotation is input to the control unit 6.

In the figure, 20 is an air cleaner, and 21 is a water temperature sensor that detects the cooling water temperature Tw of the engine 1.

Here, ignition timing control by the control unit 6 will be explained according to the routine shown in the flowcharts of FIGS. 3 and 4. In this embodiment, the functions of the rise detection means and the reference timing setting means are provided in software as shown in the flowcharts of FIGS. 3 and 4.

The routine shown in the flowchart of FIG. 3 corresponds to the rising detection means, and first, in step 1 (indicated as Sl in the figure; the same applies hereinafter), the crank angle detection pulse signal from the crank angle sensor 12 is detected. Load.

In the next step 2, it is determined whether the read pulse signal is in a high level state by comparing the level of the read pulse signal with a predetermined slice level. If the level of the pulse signal read this time is higher than the slice level and is a high level, proceed to the next step 3, but if the level of the pulse signal is lower than the slice level and is a low level, continue with this routine. finish.

When it is determined that the level of the pulse signal is equal to or higher than the slice level and the process proceeds to step 3, it is determined whether this high level determination is the first time. If it is determined that this is the first time and a rising edge of the pulse signal is detected, the process proceeds to the next step 4 and a determination is made as to whether the reference signal Ref is detected. On the other hand, if it is determined in step 3 that this is not the first time, that is, if it is determined that the level of the continuous pulse signal exceeds the slice level (is at a high level), this routine is immediately terminated.

In this way, the predetermined slice level and crank angle sensor 1
When the rising timing of the pulse signal that appears every 180 degrees of crank angle (predetermined reference crank angle position Ref) is detected by comparing the level of the detected pulse signal from No. The routine is executed.

Here, first, in step 11, the measurement time of the timer ■, which was reset to zero and restarted when the predetermined reference crank angle position Ref was detected last time, is set as the pulse signal rise interval time TRef (see Fig. 5). . In the next step 12, the timer (2) is reset to zero and restarted. That is, the timer (2) starts measurement from zero every time the predetermined reference crank angular position Ref is detected, and measures the interval time TRef between the predetermined reference crank angular positions Ref.

In the next step 13, the interval time TRef of the predetermined reference crank angular position Ref obtained in step 11, that is,
Predetermined reference crank angle position 1'Ref is crank angle 180''
If the rotation speed is 180'', the engine rotation speed N is calculated based on the time required for the crankshaft to rotate 180''.

Then, in the next step 14, the basic fuel injection amount T
The ignition timing ADV (a value expressing the number of crank angle positions before the upper row point in degrees), which is stored in correspondence with p and engine rotational speed N, is stored in correspondence with the current basic fuel injection amount Tp and engine rotational speed. This is determined by searching the map based on the speed N.

Note that the basic fuel injection amount Tp is based on the intake air flow rate Q and the engine rotation speed N, and is calculated as Tp - KXQ/N (K is a constant).
It is calculated according to the following formula, and the value calculated in the fuel injection amount setting control routine may be read.

When the ignition timing ADV is retrieved, the position of this ignition timing ADV in terms of crank angle from a predetermined reference crank angle position tRef is calculated, and furthermore, this crank angle is converted into time based on the engine rotation speed N. Then, the time ADVT from the predetermined reference crank angle position Ref to the ignition timing ADV is determined.

For example, the predetermined reference crank angle position Ref defined by the opening position of the slit 17 is 70'' before top dead center,
When the ignition timing ADV is at a position 40 degrees before top dead center, the desired ignition timing ADV is at a point rotated by 30 degrees from the predetermined reference crank angle position Ref. This is calculated based on the obtained engine rotational speed N.

When the time ADVT from Ref to the ignition timing ADV is obtained as described above, in the next step 16, the time ADV
Predetermined response delay time (rise delay time) CAD of the phototransistor that constitutes the crank angle sensor 12 from T
LY is subtracted and corrected, and a new time ADVT is set. In this way, the time ADVT is converted into the predetermined response delay time CAD.
The reason for correcting based on LY is as follows.

That is, when a relatively inexpensive phototransistor is used as a crank angle sensor, there is a predetermined response delay time CADLY from when the phototransistor is hit by the light from the light emitting diode until its output exceeds the slice level. , this delay time CADLY is a constant value regardless of the engine rotation speed N. Therefore, even if the opening position of the slit 17 with respect to the signal disk plate 14 is set to a desired crank angle position and the pulse signal is set to rise at the desired crank angle position, the response delay time CADLY as described above is If it exists, it will actually be determined that the predetermined reference crank angular position Ref is reached after this response delay time CADLY has elapsed from the desired crank angular position. Therefore, the point at which the pulse signal output from the crank angle sensor 12 exceeds the slice level is considered to be the predetermined reference crank angle position Ref defined by the opening position of the slit 17, and the ignition timing is adjusted from this point onwards. If you set the time ADVT to ADV, this time A
The DVT is delayed by the response delay time CADLY from the desired ignition timing ADV, and is ignited later than the desired ignition timing ADV.

In order to avoid such inconvenience, the response delay time C from when the phototransistor is hit by light from the light emitting diode until its output level exceeds a predetermined slice level is determined in advance.
ADLY is determined in advance, and the reference crank angle position Ref, which is determined by comparison with the slice level with respect to the intended reference crank angle position defined by the opening position of the slit 17, is detected after the response delay time CADLY has elapsed. Assuming that there is, the response delay time CADLY is subtracted from the time ADVT until the ignition timing ADV, and the time ADVT is corrected. Then, the response delay time CAD is determined based on the reference crank angle position 11Ref detected by comparison with the slice level.
This allows the desired ignition timing ADV to be detected in consideration of LY (see Fig. 5).

When the time ADVT from the detected predetermined reference crank angle position Ref to the ignition timing ADV is corrected and newly set based on the response delay time CADLY of the phototransistor in step 16, in the next step 17, the time ADVT from Ref to the ignition timing ADV is set. The timer ■ for measuring the time ADVT is started from zero.

Then, in the next step 1 day, it is determined whether or not the time measured by the timer 2 exceeds the time ADVT, and the determination in step 1 is repeated until the time measured by the timer 2 exceeds the time ADVT, When the time measured by the timer (2) exceeds the time ADVT, the process proceeds to step 19 and an ignition signal is output.

In this way, when controlling the ignition timing ADV from the predetermined reference crank angle position Ref, the time AD from the predetermined reference crank angle position Ref to the ignition timing ADV is adjusted by correcting the response delay time CADLY of the phototransistor.
If a VT is installed, even if there is a response delay time CADLY in the phototransistor that constitutes the optical crank angle sensor 12, by calculating the response delay time CADLY in advance, it can be determined by comparing it with the slice level. Desired ignition timing A based on the rising timing of the pulse signal
DV can be detected with high accuracy.

In this embodiment, the engine rotation speed N is detected based on the interval time TRef of the predetermined reference crank angle position Ref, but the engine rotation speed N is detected based on the pulse width of the pulse signal output from the crank angle sensor 12. It may be configured to calculate N. In this case, the time from the rise to the fall determined by comparison with the slice level,
By configuring the phototransistor to add the response delay time CADLY, it is possible to accurately calculate the engine rotational speed N based on the pulse width.

<Effects of the Invention> As explained above, according to the present invention, in an optical crank angle sensor that detects the crank angle position of an internal combustion engine, even if there is a response delay time in the phototransistor,
This has the effect that, for example, time control of ignition timing, etc. can be performed with high accuracy using a predetermined reference crank angle position defined by the slit position as a measurement reference.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of the present invention, FIG. 2 is a system schematic diagram showing an embodiment of the present invention, FIGS. 3 and 4 are flowcharts showing control details in the above embodiment, respectively, and FIG. 5 6 and 7 are time charts showing the characteristics of ignition timing control using conventional time control, respectively, and FIG. 8 is based on the time error of ignition timing. 5 is a graph showing changes in ignition angle error in response to engine rotational speed. ■...WA section 6...Control unit 8.
...Ignition plug 9...Ignition coil 10...Distributor 11...Power transistor
12... Crank angle sensor 14... Signal disk plate 15... Detection section 17... Slit patent applicant Japan Electronics Co., Ltd. Representative Patent attorney Fujio Sasashima Figure 3 Figure 4 2 @ Figure 5 Figure 16 Figure 7

Claims (1)

[Claims] A plurality of slits are formed through the same circumference of a signal disk plate that rotates in synchronization with the rotation of the internal combustion engine, and the light from the light source that passes through the slits is detected by a phototransistor, and the periodicity synchronized with the rotation of the engine is detected. In an optical crank angle sensor that outputs a pulse signal, a rise detection means detects the rise of the pulse signal by comparing it with a predetermined slice level, and a rise timing detected by the rise detection means is detected by a predetermined response of the phototransistor. A response delay correction device for an optical crank angle sensor, comprising: reference timing setting means for correcting based on the delay time and setting the corrected rise time as a reference rise time.