JPS61104215A - Self-diagnosing apparatus of crank-angle sensor - Google Patents

Abstract

PURPOSE:To self-diagnose positively and precisely acting condition of a crank- angle sensor, by calculating a ratio of change of frequency of a detecting signal from the crank-angle sensor and judging an abnormality by its magnitude. CONSTITUTION:A crank-angle sensor A generates a detecting signal P by a pulse every time when an engine crankshaft passes the reference rotational position. A detecting signal frequency counting means C counts period T1 of the signal P per every signal P. Next, a ratio of change calculating means c divides the currently counted period T1 by the previously detected period T0. By this arrangement, the ratio of change of period of the signal P is calculated per each signal P. Later a judging means self-diagnoses acting condition of the sensor A basing on the calculated ratio of change.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a self-diagnosis device for a crank angle sensor, particularly to one used in a control unit that controls the operation of an automobile engine.

<Prior art> In a control unit that controls the operation of an automobile engine,
Engine control equipment such as a fuel injection device is controlled based on a pulsed crank angle detection signal that is generated every time the engine's crankshaft rotates by a predetermined angle.

Incidentally, in order for this type of control unit to operate normally, it is a prerequisite that the operating state of the crank angle sensor that generates the crank angle detection signal is always normal. Therefore, it is desirable that this type of control unit be equipped with a device that self-diagnoses the operating state of the crank angle sensor.

As shown in Figures 5 and 6, the conventional crank angle sensor self-diagnosis device detects the problem only for a certain period of time (approximately 1 second) after the start switch for starting the engine is turned from OFF to ON. It was configured to detect the presence or absence of a crank angle detection signal, and if a crank angle detection signal was detected during that time, it was determined to be normal, and if there was no crank angle detection signal during that time, it was determined to be abnormal.

(Problems to be Solved by the Invention) However, the crank angle sensor self-diagnosis device described above only operates when the engine is started, and therefore it is not possible to self-diagnose malfunctions after engine startup. The drawback was that it couldn't be done. Furthermore, since the self-diagnosis operation is carried out by borrowing another function, that is, the function of the start switch, there is also a drawback that if the start switch itself has an abnormality, it will not be able to operate normally. Furthermore, at the time of starting, the load on the vehicle battery becomes heavy, so the electromotive force of the battery decreases significantly.
This also has the disadvantage that there is a high possibility that malfunctions will occur.

The present invention solves the above problems, and includes:
The operational status of the crank angle sensor can be self-diagnosed using only the detection signal from the crank angle sensor without using any other functions, and the self-diagnosis can be performed during rotation after starting the engine. It is an object of the present invention to provide a self-diagnosis device for a crank angle sensor that can perform self-diagnosis of the operating state of a crank angle sensor reliably and accurately.

(Means for Solving the Problems) As a means for achieving the above object, the present invention provides a detection signal period measurement method that measures the period of a detection signal from a crank angle sensor A, as shown in FIG. means B, change rate calculation means C for calculating the rate of change of the detected period, and determination means for determining whether or not the operation of the crank angle sensor A is abnormal based on the magnitude of the calculated rate of change. It is characterized by having the following.

Effect> With the above means, the operating state of the crank angle sensor can be self-diagnosed based only on the detection signal from the crank angle sensor, and the self-diagnosis can be continuously performed after the engine is started. Thereby, the operating state of the crank angle sensor can be reliably and accurately self-diagnosed.

<Example>
Hereinafter, preferred embodiments of the present invention will be described based on the drawings.

FIG. 2 shows an embodiment of the crank angle sensor self-diagnosis device according to the present invention.

The self-diagnosis device shown in the figure is configured using the functions of an on-vehicle control unit 1 that controls the operation of an automobile engine.

The control unit 1 includes CPU11. RAM12. ROM1
3. Human output interface ([/F)14. and a crystal oscillator 15 for generating a reference clock pulse signal. This control unit 1 includes a crank angle sensor 21. Air flow meter 22. Detection signals from other input devices 23 and the like are input. Further, this control unit 1 outputs signals for controlling engine control equipment 312 such as a fuel injection device and an ignition device, a display device 32, and the like.

The crank angle sensor 21 is a kind of rotational pulse encoder, and outputs two types of pulse detection signals P1 and P2 every time the engine crankshaft rotates by a predetermined angle. The detection signal PI indicates that the engine crankshaft is at a predetermined reference rotational position (for example, 180° for a 4-cycle 4-cylinder engine).
It is emitted every time the motor passes the standard rotation position).

The detection signal P2 is generated every time the engine crankshaft rotates by a predetermined pinch angle (for example, 1 degree). here,
In this embodiment, the former detection signal P1 is used for self-diagnosis of the crank angle sensor 21.

FIG. 3 shows an example of the waveform of the crank angle detection signal PL.

The control unit 1 has a software-based function for self-diagnosing the crank angle sensor 21 based on the cycles To and T+ of the crank angle detection signal P1 shown in FIG.

FIG. 4 shows the configuration of the self-diagnosis device portion of the crank angle sensor configured in the control unit 1 according to its operation flow.

In FIG. 4, the control unit 1 first measures the cycle T+ of the detection signal P1 from the crank angle sensor for each detection signal.

Next, the laps measured this time! An arithmetic operation is performed to divide 'Jl 'r l by the previously measured period T0. Thereby, the rate of change in the period of the detection signal P1 is T + /T.

is calculated for each detection signal.

Thereafter, the operating state of the crank angle sensor is self-diagnosed based on the magnitude of the calculated rate of change T + /T o. Here, when the rate of change T I/To goes out of a certain range, for example, T + /T.

>2.0 or TI/T0<o,5, it is determined to be abnormal. Then, if necessary, display/warning is performed. Also, when the rate of change is within a certain range, for example 0.5
< T + / T o < 2.0 (7) It is judged as normal.

Here, the rate of change T + /T o changes greatly depending on acceleration and deceleration of the engine, but there is a limit to the magnitude of the change in the engine in a normal state. Therefore,
If the range of the rate of change 'r+/T0, which is the standard for the above judgment, is increased to a certain level (for example, 0.5 to 2.0), engine acceleration will not be affected by deceleration, and the crank angle It is possible to reliably determine whether there is an abnormality in the sensor. In addition, the rate of change in the case of normal acceleration is 0 at maximum.
．． 6. The maximum rate of change in the case of deceleration is about 1.4.

Self-diagnosis of the operating status of the crank angle sensor is performed as described above, but what should be noted here is that the diagnosis is performed only based on the detection signal from the crank angle sensor. be. Thereby, the operating state of the crank angle sensor can be self-diagnosed without relying on other functions, and the self-diagnosis can be continuously performed while the engine is rotating after starting. Thereby, self-diagnosis of the operating state of the crank angle sensor can be performed reliably and accurately.

<Effects of the Invention> As is clear from the description of the embodiments above, the crank angle sensor self-diagnosis device according to the present invention can self-diagnose the operating state of the crank angle sensor based only on the detection signal from the crank angle sensor. In addition, the self-diagnosis can be performed continuously after the engine is started, thereby providing the effect that the operating state of the crank angle sensor can be reliably and accurately self-diagnosed.

[Brief Description of the Drawings] Fig. 1 is a diagram showing the configuration of the present invention, Fig. 2 is a block diagram showing an embodiment of a self-diagnosis device for a crank angle sensor according to the present invention, and Fig. 3 is a diagram showing a crank angle sensor self-diagnosis device according to the present invention. A waveform chart showing the angle detection signal and its period, FIG. 4 is a flowchart showing the operation of the device of the present invention shown in FIG. 2, and FIG. 5 is a waveform chart showing the operation of the conventional crank angle sensor self-diagnosis device. FIG. 6 is a flowchart showing the operation of a conventional crank angle sensor self-diagnosis device. 1... Control unit 21... Crank angle sensor patent applicant Japan Electronics Co., Ltd. Agent Patent attorney Fujio Sasashima Figure 1 Figure 2

Claims (1)

[Claims] A device for self-diagnosing the operating state of a crank angle sensor that generates a detection signal every time the crankshaft rotates by a predetermined angle, includes a detection signal period measuring means for measuring the period of the detection signal, and a detection signal period measuring means for measuring the period of the detection signal, and a detection signal period measuring means for measuring the period of the detection signal. A self-diagnosis for a crank angle sensor, comprising: a change rate calculation means for calculating the change rate; and a determination means for determining whether or not the operation of the crank angle sensor is abnormal based on the magnitude of the calculated change rate. Device.