JPS63111412A - Self-diagnostic device for crank angle detector - Google Patents

Abstract

PURPOSE:To decide the abnormality of a crank angle detector by comparing the duty ratio of a unit angle pulse signal outputted according to the rotation of the crank shaft of an internal combustion engine with a normal duty ratio and detecting its error. CONSTITUTION:A crank angle sensor 3 outputs the pulse signal with pulse width corresponding to a specific crank angle at intervals of the reference angle and unit angle rotation of the crank shaft. A control unit 9 detects the duty ratio of the detected pulse signal and compares the duty ratio with the previously stored normal duty ratio to measure its error. When this error exceeds a specific value, a crank angle detector 3 decides abnormality. When the crank angle detector 3 decides that the error is within a normal range, the control unit 9 performs fuel control over the engine 1 according to the detected crank angle.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a self-diagnosis device for a crank angle detection device that detects the rotation angle of a crankshaft of an internal combustion engine.

<Prior Art> For example, in an internal combustion engine equipped with an electronically controlled fuel injection device, it is necessary to constantly detect the rotation angle of the crankshaft in order to control the fuel injection amount, ignition timing, and the like.

Therefore, this type of internal combustion engine is equipped with a crank angle detection device (see Japanese Patent Laid-Open Publication No. 155540/1983).

An example of such an internal combustion engine is shown in FIG.

The distributor 2 attached to the internal combustion engine 1 includes a photoelectric crank angle sensor 3 as a crank angle detection device.
is built-in. The crank angle sensor 3 includes a signal plate 5 that rotates together with the distributor shaft 4 and a detection section 6. The signal plate 5 has 360 position signals Po arranged at equal intervals.
5 (unit angle pulse signal per rotation of unit angle 1°) slit 7, and in the case of 4 cylinders, 4 reference signals Ref
(Reference angle 180" reference angle pulse signal for each rotation)
A slit 8 for use is formed. The detection unit 6 detects these slits 7.8 and generates a position signal Pos, which is a pulse signal having a pulse length corresponding to a predetermined crank angle.
and a reference signal Ref.

The output of the crank angle sensor 3 is input to the control unit 9, and the control unit 9 calculates the engine rotational speed N by measuring the number of inputs of the position signal Pos or the cycle of the reference signal Ref per unit time. The basic fuel injection ff1Tp is calculated from the engine rotational speed N and the intake airflow IQ detected by the airflow meter 10. Then, this basic fuel injection fiTp is corrected based on the engine cooling water temperature, the change in the opening of the throttle valve 15 detected by the throttle valve opening sensor 16 (the acceleration/deceleration state of the engine 1), etc., to obtain the final fuel injection value. An injection amount Ti is set, and an injection pulse signal in a pulse corresponding to this fuel injection amount Ti is output to the fuel injection valve 11.

Further, the control unit 9 controls the ignition standard set based on the reference signal Ref in order to cause the spark plug 12 to ignite the spark at a predetermined ignition timing set based on the basic fuel injection amount 'rp and the engine speed N. The position signal Pos is counted from the signal, and when the count reaches a number corresponding to a predetermined time, the ignition coil 13
By controlling the power transistor 14 attached to the ignition coil 13, the high voltage generation timing of the ignition coil 13 is controlled.

<Problems to be Solved by the Invention> As mentioned above, the position signal Pos and the reference signal Ref output from the crank angle sensor are important information that influences the operation of the engine. When an abnormality occurs, desired fuel injection control and ignition timing control cannot be performed. For this reason, conventionally, for example, the number of pulses of the position signal Pos included in one cycle of the reference signal Ref is constant, and the measured cycle of the reference signal Ref is a predetermined multiple of the cycle of the position signal Pos. The engine was equipped with a self-diagnosis device that determines whether the crank angle sensor is abnormal when the crank angle sensor is not in use.

However, according to the above-mentioned conventional self-diagnosis device, when both the reference signal Ref and the position signal Pos are interrupted due to a break in the signal line, etc., the period of each is assumed to be infinite, so there is a problem that abnormality cannot be determined. there were. Another problem is that self-diagnosis cannot be performed when the measured period of the reference signal Ref is a predetermined multiple of the period of the position signal Pos, even though an abnormality occurs in the reference signal Ref and the position signal Pos at the same time. There was also.

The present invention has been made in view of the above problems, and provides a self-diagnosis device for a crank angle detection device that can self-diagnose even when an abnormality occurs in the reference signal Ref and the position signal Pos at the same time. The purpose is to improve the accuracy of diagnosis.

Therefore, in the present invention, as shown in FIG. 1, a pulse signal having a pulse length of a predetermined crank angle for each reference angle and unit angle rotation of the crankshaft of an internal combustion engine In the crank angle detection device that emits the unit angle pulse (
A unit angle pulse duty ratio detection means for detecting the duty ratio of No. 3, a normal duty ratio based on the pulse of the unit angle pulse signal corresponding to a predetermined crank angle, and a unit angle detected by the unit angle pulse duty ratio detection means. The self-diagnosis device is configured to include an abnormality determining means for comparing the duty ratio of the pulse signal and determining an abnormality in the crank angle detecting device when there is an error of a predetermined value or more.

<Operation> The reference angle pulse signal emitted for each reference angle of the crankshaft and the unit angle pulse signal emitted for each unit angle each have a pulse duration of a predetermined crank angle, so even if the pulse is normal, For example, each pulse signal should have a predetermined duty ratio when the engine rotational speed is constant.

In addition, in the case of a reference angle pulse signal with a relatively long cycle, when the engine rotation speed changes, the normal pulse signal is greatly affected and the duty ratio changes every cycle, but the unit angle with a relatively short cycle is With the pulse signal, the duty ratio will maintain a substantially constant value even if the engine rotational speed changes.

Therefore, the duty ratio of the detected unit angle pulse signal is based on the predetermined crank angle of the predetermined pulse width (regular duty ratio (for example, in the photoelectric crank angle sensor shown in the conventional example, the duty ratio is When there is a large error with respect to the duty ratio (determined by the slit width and slit interval for the signal Pos),
It can be assumed that a shift in the duty ratio has occurred due to the introduction of noise or momentary interruption of pulses, and this is used to perform self-diagnosis of the crank angle detection device.

<Example> An embodiment of the present invention will be described below based on the drawings.

In this embodiment, a self-diagnosis device for a crank angle detection device applied to an internal combustion engine equipped with an electronically controlled fuel injection device as described in the conventional example is assumed, and the system diagram shown in FIG. 2 is used. explain.

Here, the reference signal Ref (reference angle pulse signal) and position signal Po5 (unit angle pulse signal) from the crank angle sensor 3 as a crank angle detection device are input to the control unit 9 as in the conventional case. However, in this embodiment, the control unit 9 controls the duty ratio τ (O in one cycle) of the position signal Pos, as shown in the flowchart of FIG.
N time ratio, as shown in Figure 4 =to/(t
The self-diagnosis of the crank angle sensor 3 is performed by detecting the difference between 100% and 100%) and comparing it with the normal duty ratio predetermined by the width and interval of the slit 7 formed in the signal plate 5. .

Therefore, in this embodiment, the control unit 9 serves both as unit angle pulse signal duty ratio detection means and abnormality determination means.

Next, self-diagnosis by the control unit 9 will be explained according to the flowchart shown in FIG.

In step 1 (indicated as "S" in the figure, the same applies hereinafter), the OFF time tL of the position signal Pos output from the crank angle sensor 3 is measured, and in the next step 2, the ON time 1N of the position signal Pos is measured. Measure.

In step 3, the duty ratio τ is calculated from the FF time tL and ON time 1H of the position signal Pos measured in steps 1 and 2 (τ=t, I/(tn
+tt) x 100%).

In step 4, the tolerance range (within ±20% of the normal duty ratio τ1 determined by the width and spacing of the slit 7)
It is determined whether the duty ratio τ calculated in step 3 is included in the allowable error range). As mentioned above, the reason why ±20% of the normal duty ratio τ1 is set as the allowable range is that due to changes in the engine speed N, the calculated duty ratio τ may not completely match the normal duty ratio τ even under normal conditions. Therefore, the range close to 1 in terms of normal duty ratio is set as the permissible range.

Here, if the measured duty ratio τ is not included in the tolerance range of ±20% of the normal duty ratio τ, noise may be mixed into the position signal Pos or momentary pulse interruption may occur, as shown in FIG. 4, for example. Assuming that the duty ratio τ is the normal duty ratio and is large (deviating from the normal duty ratio), the process proceeds to step 5 and an NG determination is made.

As described above, the duty ratio τ of the position signal Pos
is detected and compared with the regular duty ratio τ, and if it is approximately equal to the regular duty ratio τ1, the crank angle sensor 3
is determined to be normal, and when it deviates significantly from the normal duty ratio τ, it is assumed that a problem such as noise mixing or instantaneous interruption has occurred, and an abnormality of the crank angle sensor 3 is determined.

Therefore, there is no need to perform self-diagnosis based on the correlation between the reference signal Ref and the position signal Pos as in the past.
Self-diagnosis is possible even if an abnormality occurs in s and s at the same time.

Therefore, it is possible to accurately self-diagnose an abnormality in the crank angle sensor 3, and if an abnormality occurs, the output of the rank angle sensor 3 (
It is possible to satisfactorily avoid performing fuel control and ignition timing control of the engine 1 based on the reference signal Ref and position signal Po5).

Note that in this embodiment, the normal duty ratio τ.

Although the permissible range is within ±20% of , the permissible range may be varied based on the direction of rotational speed change, the measurement order of the OFF time tL and the ON time t□, etc.

<Effects of the Invention> As explained above, according to the present invention, since self-diagnosis is performed based on the duty ratio of the unit angle pulse signal, self-diagnosis is performed even when an abnormality occurs in the reference angle pulse signal and the unit angle pulse signal at the same time. This has the effect of improving the accuracy of self-diagnosis of the crank angle detection device.

[Brief explanation of the drawing]

Fig. 1 is a configuration diagram of the present invention, Fig. 2 is a system schematic diagram of an electronically controlled fuel injection internal combustion engine common to an embodiment of the present invention and a conventional example, and Fig. 3 is a self-inspection control in the same embodiment. The flowchart shown in FIG. 4 shows the position signal Po5 (
2 is a time chart showing changes in the duty ratio of the unit angle pulse signal during normal and abnormal times; 1... Engine 3... Crank angle sensor 9...
・Control unit 15... Throttle valve 1
6...Throttle valve opening sensor patent applicant Japan Electronics Co., Ltd. Agent Patent attorney Fujio Sasashima No. 1 Uchimuhohata, Seki Crank south detection mounting diagram standard

Claims (1)

[Claims] In a crank angle detection device that emits a pulse signal having a pulse width corresponding to a predetermined crank angle for each reference angle and unit angle rotation of a crankshaft of an internal combustion engine, a unit angle pulse duty detecting a duty ratio of the unit angle pulse signal. The ratio detection means compares the normal duty ratio based on the pulse width of the unit angle pulse signal corresponding to a predetermined crank angle with the duty ratio of the detected unit angle pulse signal, and detects the crank angle when there is an error of more than a predetermined value. A self-diagnosis device for a crank angle detection device, comprising: an abnormality determining means for determining an abnormality in the device.