JPH01110216A - Crank angle detector for internal combustion engine - Google Patents

Abstract

PURPOSE:To enable an engine control such as ignition timing control in the same fashion as in the normal operation, by generating a pseudo signal for a signal generated per unit angle of rotation of a crank shaft from a crank angle detector when the signal is abnormal. CONSTITUTION:When abnormality is detected by a unit angle pulse signal abnormality detection means in a pulse signal outputted per unit angle of rotation of a crank shaft from a crank angle detector, a pseudo unit angle pulse signal is generated by a pseudo unit angle pulse signal generation means according to a cycle determined based on the cycle of a reference angle pulse signal. This enables execution of various engine controls using a signal per unit angle of rotation in almost the same fashion as in the normal operation.

Description

Detailed Description of the Invention <Industrial Application Field> The present invention relates to a crank angle detection device that detects the rotation angle of a crankshaft of an internal combustion engine. Regarding fail-safe technology in the event of signal abnormality.

<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 electronically controlled fuel injection type 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 (rotates twice per crankshaft rotation) and a detection section 6. The signal plate 5 includes:
360 equally spaced slits 7 for position signals Po5 (unit angular pulse signal for every 2° unit angle rotation of the crankshaft) and 4 reference signals Ref in the case of a 4-cylinder engine.
(a reference angle pulse signal every 180° reference angle rotation of the crankshaft) slit 8 is formed. Detection section 6
detects these slits 7.8 and outputs a position signal Pos and a reference signal Ref, which are pulse signals having a pulse width corresponding to a predetermined crank angle.

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 input position signals Pos or the cycle of the reference signal Ref per unit time. Engine speed N and air flow meter 1
The basic fuel injection amount 'rp (=KXQ/N; K is a constant) is calculated based on the intake air flow rate Q detected by 0. Then, the second basic fuel injection ITp is corrected based on the engine cooling water temperature, etc. to set the final fuel injection amount Ti, and an injection pulse signal with a pulse width corresponding to this fuel injection amount Ti is sent to the fuel injection valve. Output to 11.

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

In FIG. 2, 15 is a throttle valve, and 16 is a throttle sensor that detects the opening degree of the throttle valve 15.

<Problems to be Solved by the Invention> As mentioned above, the reference signal Ref and position signal Pos output from the crank angle sensor are important information that influences the operation of the engine. When this occurs, desired fuel injection control and ignition timing control cannot be performed.

For example, when controlling the ignition timing based on the output of the crank angle sensor 3 as described above, if an abnormality occurs in the position signal Pos and the desired ignition timing cannot be specified based on the count number of the position signal Pos, for example, Conventionally, the crank angle from the reference signal Ref to the ignition timing was converted into time based on the cycle of the reference signal Ref, and the ignition timing was determined by measuring the time from the reference signal Ref.

However, with this method of determining ignition timing by converting it into time, it is necessary to convert the crank angle up to the ignition timing into time each time the ignition timing of each cylinder is controlled, which increases the software burden on the control unit. There was a problem.

The present invention has been made in view of the above problems, and even when an abnormality occurs in the pulse signal for each unit angle rotation output from the crank angle detection device, it is possible to perform ignition timing control, etc. in the same way as in a normal state. The purpose is to enable engine control.

<Means for Solving the Problems> Therefore, the present invention provides a crank angle detection method for an internal combustion engine that generates a pulse signal having a pulse width corresponding to a predetermined crank angle for each reference angle and unit angle rotation of the crankshaft of the internal combustion engine. In the apparatus, a unit angle pulse signal abnormality detection means for detecting an abnormality in the pulse signal for each unit angle rotation;
a reference angle pulse signal period measuring means for measuring the period of the pulse signal for each reference angle rotation; and setting a generation period of the pulse signal for each unit angle rotation based on the period measured by the reference angle pulse signal period measuring means. unit angle pulse generation period setting means, and when an abnormality in the pulse signal for each unit angle rotation is detected by the unit angle pulse signal abnormality detection means, based on the period set by the unit angle pulse generation period setting means. Pseudo unit angle pulse signal generating means for generating a pseudo signal of the pulse signal for each unit angle rotation is provided.

<Operation> According to this configuration, when the unit angle pulse signal abnormality detecting means detects an abnormality in the pulse signal output from the crank angle detecting device for each unit angle rotation of the crankshaft, the pseudo unit angle pulse signal generating means A pseudo unit angle pulse signal is generated according to a cycle determined based on the cycle of the reference angle pulse signal.

In other words, the time it takes for the crankshaft to rotate by a unit angle (the period of the pulse signal per unit angle rotation) can be determined from the period of the pulse signal for each reference angle rotation, so when the unit angle pulse signal is abnormal, the A pseudo pulse signal is generated separately from a pulse signal based on actual detection.

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

The present embodiment is based on an electronically controlled fuel injection internal combustion engine (four cylinders) having the same hardware configuration as the conventional example, so a detailed explanation will be omitted with reference to FIG. 2.

In this embodiment, the control unit 9 controls the reference angle 1 of the crankshaft from the crank angle sensor 3 as in the conventional case.
A reference signal Ref every 80° rotation and a position signal Pos every 2° unit angle rotation of the crankshaft are input.

Here, the control unit 9 measures the period of the reference signal Ref from the crank angle sensor 3, calculates the engine rotation speed N obtained as the reciprocal of this period, and calculates the engine rotation speed N and the air flow meter 10.
The ignition timing is set in accordance with the engine operating conditions obtained based on the intake air flow rate Q detected by referring to the map. Then, when the number of inputs of the position signal Pos since the input of the reference signal Ref matches the ignition timing, the high voltage generation timing of the ignition coil 13 is controlled by controlling the power transistor 14 attached to the ignition coil 13. is controlled to generate a spark between the electrodes of the ignition plug 12 to ignite.

In addition, in parallel with such normal ignition control, it is determined whether or not there is an abnormality such as a drop in the output of the position signal Pos, and when it is determined that there is an abnormality in the position signal Pos, the period of the reference signal Ref is The cycle of the position signal Pos is determined, the position signal Pos is generated in a pseudo manner according to this cycle, and the number of inputs of the pseudo position signal Pos is counted from the input of the reference signal Ref to determine the ignition timing and ignition processing is performed.

That is, the software function of the control unit 9 detects a unit angle pulse signal abnormality.

A reference angle pulse signal period measuring means, a unit angle pulse generation period setting means, and a pseudo unit angle pulse signal generation means are configured.

The ignition control by the control unit 9 will be explained below according to the flowcharts shown in FIGS. 3 to 6.

The routine shown in the flowchart of FIG. 3 is executed every time the reference signal Ref from the angle sensor 3 is input, and in step (indicated as S in the figure, the same applies hereinafter) 1, The value T of the timer that is reset in step 2 and starts from zero is set as the period of the reference signal Ref. This routine is executed for each reference signal Ref, so when the timer is reset to zero in step 2, the timer measures the time until the next reference signal Ref is output, and as a result, the output interval of the reference signal Ref ( It is designed to measure the period).

In step 3, the value of the count value C8 counted up in the routine (step 11) shown in the flowchart of FIG. 4 is read. The routine shown in the flowchart of FIG. 4 is based on the position signal P from the crank angle sensor 3.
It is executed every time the os is input, and the count value CI is incremented by 1 each time the routine is executed. Note that this count value C8 is reset to zero in step 9, so it counts the number of input position signals Pos between the reference signals Ref.

In the next step 4, the position signal Po between the reference signals Ref counted as described above is
The number of inputs of s is compared with the normal value Cs. In this embodiment, the reference signal Ref is output every 1806 degrees of crank angle, and the position signal Pos is output every 2 degrees of crank angle, so the normal value Cs is 90.

If it is determined in step 4 that the position signal Pos is C+'' and Cs, and the position signal Pos is normally output between the reference signals Ref, the process proceeds to step 5 to determine whether the position signal Pos is normal.

On the other hand, if it is determined in step 4 that C, < C3, and it is determined that there is a drop in the position signal Pos between the reference signals Ref, the process advances to step 6 and an abnormality determination of the position signal Pos is performed in step 1. In the next step 7, the output cycle of the position signal Pos is determined from the cycle of the reference signal Ref set in step 1, and in accordance with this cycle, the clock signal of the microcomputer is used in the next step 8. Pseudo position signal Po
generate s.

That is, in a state where the position signal Pos is missing, the crank angle from the time when the reference signal Ref is input cannot be accurately detected by counting the number of inputs of the position signal Pos.
The position signal Po from the crank angle sensor 3 is calculated according to the period of the position signal Pos predicted from the period of ef.
In this system, a pulse signal corresponding to the position signal Pos is generated in a pseudo manner in addition to the position signal Pos, and the ignition timing is detected by counting this pseudo position signal Pos.

In step 9, a count value CI (step 11 in FIG. 4), which is incremented by 1 each time the position signal Pos from the crank angle sensor 3 is input, and a pseudo position signal Pos generated based on the processing in step 8.
The count value C2, which is incremented by 1 each time , is reset to zero. The count value C2 is incremented by 1 every time the pseudo position signal Pos is generated according to the routine (step 21) shown in the flowchart of FIG. 5, and is reset to zero every time the reference signal Ref is input, like the count value CI. This makes it possible to count the number of signals generated since the reference signal Ref is input.

The routine shown in the flowchart of FIG. 6 is executed at predetermined minute intervals (for example, every 10 m5), and in step 31, the intake air flow rate Q of the engine 1 detected by the air flow meter 10 is read.

In step 32, the engine rotation speed N is calculated from the period of the reference signal Ref obtained in step 1 described above.

In step 33, the optimum ignition timing is stored in advance in accordance with the engine operating conditions obtained based on the intake air flow rate Q and the engine rotational speed N. Search and find the appropriate ignition timing data.

In step 34, it is determined whether or not the position signal Pos is abnormal based on the determination result in the routine shown in the flowchart of FIG.

Here, if it is determined that the position signal Pos output from the crank angle sensor 3 is normal, the process proceeds to step 35 and checks whether the count value C8 has reached the value corresponding to the ignition timing found by searching in step 33. When it is determined that the ignition timing has been reached (count value CI≧ignition timing), the process proceeds to step 37 and outputs an ignition signal to cause the ignition plug 12 to ignite and ignite the ignition timing. When the timing has not been reached (count value CI<ignition timing), the determination in step 35 is repeated.

That is, the position signal Pos from the crank angle sensor 3
is normal, when the number of inputs of the position signal Po5 (position signal Po5 output from the crank angle sensor 3) from the input of the reference signal Ref reaches a value equivalent to the ignition timing (for example, when the ignition timing is at the top dead end). Tea ceremony 3
When the crank angle position is 0°, ignition is performed when the count number of the position signal Pos output every 2° reaches 75).

On the other hand, if it is determined in step 34 that the position signal Pos output from the crank angle sensor 3 is abnormal,
Proceeding to step 36, similarly to step 35, it is determined whether the count value C2 has reached a value equivalent to the ignition timing searched in step 33, and if it is determined that the ignition timing has been reached, the process proceeds to step 37. By proceeding and outputting an ignition signal, the ignition plug 12 is caused to ignite.

That is, the position signal Pos from the crank angle sensor 3
When the position signal Pos is abnormal, the ignition timing is adjusted in the same way as in normal conditions using the count value C2 of the pseudo position signal Pos generated by the microcomputer, without using the value C8 obtained by counting the position signal Pos from the crank angle sensor 3. is detected and ignited.

In this way, even when the position signal Pos output from the crank angle sensor 3 is abnormal, the ignition timing is detected based on the count number of the position signal Po5 (pseudo position signal Po5) and ignition is performed as in normal times. Therefore, there is no need to increase the software burden, as is the case when, for example, the time from the input of the reference signal Ref to the ignition timing is converted into time and the ignition timing is detected by time measurement.

Incidentally, in this embodiment, ignition timing control has been described, but for example, the position signal Pos is changed from the reference signal Ref.
Even in the case where the timing of fuel injection by the fuel injection valve 11 is variably controlled by counting the number of inputs, the same injection control as in normal conditions can be performed by generating the pseudo position signal Pos as in this embodiment. Needless to say, it is.

<Effects of the Invention> As explained above, according to the present invention, when the signal emitted from the crank angle detection device for each unit angle rotation of the crankshaft is abnormal, a pseudo signal of the signal for each unit angle is generated. As a result, various engine controls performed using signals for each unit angle rotation can be executed in substantially the same manner as in the normal state, and, for example, fail-safe processing based on time conversion is unnecessary, reducing the software burden on the control unit. This has the effect of avoiding the increase.

[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 common to an embodiment of the present invention and a conventional example, and Figs. 3 to 6 show ignition timing control in the above embodiment. It is a flowchart. 1...Institution 2...Distributor 3.
... Crank angle sensor 9 ... Control unit 12 ... Spark plug 13 ... Ignition coil 14
...Power transistor patent applicant Fujio Sasashima, agent of Japan Electronics Co., Ltd., patent attorney Figure 2 Figure 1

Claims (1)

[Claims] In a crank angle detection device for an internal combustion engine that emits a pulse signal having a pulse width of a predetermined crank angle for each reference angle and unit angular rotation of a crankshaft of the internal combustion engine, an abnormality in the pulse signal for each unit angular rotation is detected. a unit angle pulse signal abnormality detection means for measuring the period of the pulse signal for each rotation of the reference angle, a reference angle pulse signal period measuring means for measuring the period of the pulse signal for each rotation of the reference angle, and a unit angle unit angle pulse generation cycle setting means for setting a generation cycle of a pulse signal for each rotation; and unit angle pulse generation when an abnormality in the pulse signal for each unit angle rotation is detected by the unit angle pulse signal abnormality detection means. A crank angle detection device for an internal combustion engine, comprising pseudo unit angle pulse signal generating means for generating a pseudo signal of the pulse signal for each unit angle rotation based on the period set by the period setting means.