JP5325148B2 - Fail-safe control device for internal combustion engine - Google Patents

Description

  The present invention relates to a fail-safe control device for an internal combustion engine having a function of calculating the rotational speed of the internal combustion engine based on an output signal of the cam angle sensor when the crank angle sensor of the internal combustion engine is abnormal.

  Generally, an engine (internal combustion engine) control system is provided with a crank angle sensor that outputs a crank angle signal in synchronization with the rotation of the crankshaft of the engine, and the output timing time of the crank angle signal output from the crank angle sensor. The engine speed is calculated based on the interval.

  Further, as described in Patent Document 1 (Japanese Patent No. 3775220), a start timing is generated based on a crank angle signal output from a crank angle sensor, and various control processes ( When a crank angle sensor abnormality is detected in a system that executes a fuel injection control process, an ignition timing control process, etc.), the pseudo-start timing is set by dividing the generation interval of the cam angle signal output from the cam angle sensor. Generate and execute various control processes based on this pseudo activation timing, and there is a new generation of a cam angle signal during these various control processes. There is one in which a pseudo start timing corresponding to this is immediately generated.

Japanese Patent No. 3775220

  The inventor creates a system for generating a pseudo start timing based on a cam angle signal output from a cam angle sensor when the crank angle sensor is abnormal, and calculating an engine rotation speed based on the time interval of the pseudo start timing. I am researching, but the following new issues were found in the research process.

  As shown in FIG. 2, for example, when the crank angle sensor is abnormal, the pseudo start timing is generated at the cam angle signal output timing, and the next cam angle signal is output after the current cam angle signal is output. During the period until immediately before, the pseudo start timing is generated at a time interval T30 obtained by equally dividing the time interval T180 of the output timing of the previous and current cam angle signals into six, and the crank counter is generated for each pseudo start timing thus generated. Count up.

  In this case, the time interval T30 of the pseudo activation timing is all equal from the pseudo activation timing at the time of output of the current cam angle signal to the pseudo activation timing immediately before the output of the next cam angle signal. The time interval between the pseudo start timing when the cam angle signal is output and the pseudo start timing immediately before it (hereinafter referred to as the “time interval of the pseudo start timing when the cam angle signal is output”) T30 (x) is the next cam angle signal. Therefore, there is a tendency to vary greatly compared to the time interval T30 of other pseudo activation timings. For example, during acceleration, the next cam angle signal output timing is advanced, so that the time interval T30 (x) of the pseudo activation timing when the cam angle signal is output is shortened. On the other hand, at the time of deceleration, the output timing of the next cam angle signal is delayed, so that the time interval T30 (x) of the pseudo activation timing at the time of cam angle signal output becomes longer.

  For this reason, when calculating the engine speed based on the time interval T30 of the pseudo start timing generated based on the output signal (cam angle signal) of the cam angle sensor, the time interval of the pseudo start timing when the cam angle signal is output. When T30 (x) is used, as shown by a two-dot chain line in FIG. 6, the calculated value of the engine speed is affected by the fluctuation of the time interval T30 (x) of the pseudo start timing when the cam angle signal is output. There is a problem that it fluctuates significantly.

  Therefore, the problem to be solved by the present invention is that when the rotational speed of the internal combustion engine is calculated based on the pseudo start timing generated based on the output signal of the cam angle sensor when the crank angle sensor is abnormal, An object of the present invention is to provide a fail-safe control device for an internal combustion engine that can suppress fluctuations in the calculated value of the rotational speed.

In order to solve the above-described problems, a first aspect of the invention relates to a crank angle sensor that outputs a crank angle signal in synchronization with rotation of a crankshaft of an internal combustion engine, and a cam in synchronization with rotation of a camshaft of the internal combustion engine. In a fail-safe control device for an internal combustion engine having a cam angle sensor that outputs an angle signal, when the crank angle sensor is normal, the rotational speed of the internal combustion engine is calculated based on the time interval of the output timing of the crank angle signal When the rotation speed calculation means and the crank angle sensor are abnormal, the pseudo start timing is generated at the cam angle signal output timing, and the period from when the cam angle signal is output until immediately before the next cam angle signal is output is A pseudo start timing generator that generates a pseudo start timing at time intervals obtained by equally dividing the time interval of the output timing of the cam angle signal that has already been output into a plurality of times. If, when the crank angle sensor abnormality, a abnormal rotation speed calculation means for calculating the rotational speed of the internal combustion engine based on the integrated value of the time interval of the pseudo start timing, this abnormal rotation speed calculation means, the pseudo start When calculating the rotation speed of the internal combustion engine based on the integrated value of the timing time interval, the time interval between the pseudo start timing at the cam angle signal output and the immediately preceding pseudo start timing of the pseudo start timing time interval (Hereinafter referred to as “the time interval of the pseudo start timing when the cam angle signal is output”) is excluded, and the rotational speed of the internal combustion engine is calculated .

In this configuration, when the rotation speed of the internal combustion engine is calculated based on the integrated value of the time interval of the pseudo start timing when the crank angle sensor is abnormal, the pseudo start timing at the time of cam angle signal output and the pseudo start timing immediately before that are output. Time interval (hereinafter referred to as “the time interval of the pseudo start timing when the cam angle signal is output”), so that the time interval of the pseudo start timing when the cam angle signal is output is not affected by the fluctuation. The rotational speed of the internal combustion engine can be calculated, and fluctuations in the calculated value of the rotational speed of the internal combustion engine can be suppressed.

In this case, as in claim 1, if to calculate the rotational speed of the internal combustion engine based on the integrated value of the time interval of the pseudo start timing, it is possible to improve the calculation accuracy of the rotational speed of the internal combustion engine.

When calculating the integrated value of the time interval of the pseudo activation timing, the time interval of the pseudo activation timing is actually measured, and the measurement value of the time interval of the pseudo activation timing is accumulated to accumulate the time interval of the pseudo activation timing. Although the value may be obtained, the pseudo start timing is obtained by integrating the time intervals (= the time intervals of the pseudo start timing) obtained by equally dividing the time interval of the cam angle signal output timing into a plurality of times as in claim 2. The integrated value of the time interval may be obtained. In this way, it is not necessary to actually measure the time intervals of the pseudo activation timing, and the arithmetic processing for obtaining the integrated value of the time intervals of the pseudo activation timing can be simplified.

According to a third aspect of the present invention, the normal rotation speed calculation means is configured such that when the crank angle sensor is normal, the internal combustion engine calculates a predetermined crank angle for calculating the normal rotation speed based on the time interval of the output timing of the crank angle signal. The time required for rotation is calculated, and the rotation speed of the internal combustion engine is calculated based on the time required for rotating the predetermined crank angle for normal rotation speed calculation. Based on the timing interval, the time required for the internal combustion engine to rotate the predetermined crank angle for calculating the abnormal rotation speed is calculated, and the time required for rotating the predetermined crank angle for calculating the abnormal rotation speed is calculated. Based on this, the rotational speed of the internal combustion engine is calculated, and the predetermined crank angle for calculating the abnormal speed is larger than the predetermined crank angle for calculating the normal speed.

  When the crank angle sensor is abnormal, it is not necessary to detect and precisely control fluctuations in the rotational speed of the internal combustion engine during fail safe, which calculates the rotational speed of the internal combustion engine based on the time interval of the pseudo start timing. The rotational speed of the internal combustion engine is based on the time required for the internal combustion engine to rotate at a predetermined crank angle for abnormal rotation speed calculation (for example, 360 CA) that is larger than a predetermined crank angle for normal rotation speed calculation (for example, 90 CA). By calculating this, it is possible to effectively suppress fluctuations in the calculated value of the rotational speed of the internal combustion engine.

FIG. 1 is a diagram showing a schematic configuration of an engine control system in Embodiment 1 of the present invention. FIG. 2 is a time chart for explaining a method for generating the pseudo activation timing. FIG. 3 is a flowchart for explaining the flow of processing of the main engine speed calculation routine. FIG. 4 is a flowchart for explaining the processing flow of the normal engine speed calculation routine. FIG. 5 is a flowchart for explaining the flow of processing of the engine speed calculation routine at the time of abnormality of the first embodiment. FIG. 6 is a time chart for explaining the effect of the first embodiment. FIG. 7 is a flowchart for explaining the processing flow of the abnormal-time engine rotation speed calculation routine according to the second embodiment. FIG. 8 is a time chart for explaining the effect of the second embodiment. FIG. 9 is a diagram illustrating a method for calculating the engine speed when the crank angle sensor is abnormal in the third embodiment.

  Hereinafter, some embodiments embodying the mode for carrying out the present invention will be described.

A first embodiment of the present invention will be described with reference to FIGS.
First, the overall configuration of the engine control system will be schematically described with reference to FIG.
A throttle valve 14 is provided in the middle of the intake pipe 13 connected to the intake port 12 of the engine 11, and the opening (throttle opening) of the throttle valve 14 is detected by a throttle opening sensor 15. Further, an intake pipe pressure sensor 15 for detecting an intake pipe pressure is provided on the downstream side of the throttle valve 14, and fuel injection for injecting fuel toward the intake port 12 in the vicinity of the intake port 12 of each cylinder. A valve 16 is attached. In addition, a spark plug 17 is attached to each cylinder of the cylinder 11 of the engine 11, and the air-fuel mixture in the cylinder is ignited by spark discharge of the spark plug 17 of each cylinder.

  On the other hand, an exhaust gas purifying catalyst 20 is installed in the middle of the exhaust pipe 19 connected to the exhaust port 18 of the engine 11. The cylinder block of the engine 11 is provided with a cooling water temperature sensor 21 that detects the cooling water temperature.

  Further, a crank angle sensor 24 is installed opposite to the outer periphery of the signal rotor 23 attached to the crankshaft 22 of the engine 11, and a predetermined value is synchronized with the rotation of the signal rotor 23 (crankshaft 22) from the crank angle sensor 24. A crank angle signal (pulse signal) is output for each crank angle (for example, every 30 CA). When the crank angle sensor 24 is normal, the crank counter is counted up every output timing of the crank angle signal (for example, every rising timing or falling timing of the crank angle signal).

  Further, a cam angle sensor 27 is installed facing the outer periphery of the signal rotor 26 attached to the cam shaft 25 of the engine 11, and a predetermined value is synchronized with the rotation of the signal rotor 26 (cam shaft 25) from the cam angle sensor 27. The cam angle signal (pulse signal) is output at the cam angle. Based on this cam angle signal, ON / OFF of the G2 signal for cylinder discrimination is switched, for example, the timing of the G2 edge (the timing of the effective cam edge of the G2 signal) every 180 CA. When the crank angle sensor 24 is abnormal, a pseudo start timing is generated based on the output timing of the cam angle signal corresponding to the timing of the G2 edge, and the crank counter is counted up at each pseudo start timing.

  Outputs of the various sensors described above are input to an engine control circuit (hereinafter referred to as “ECU”) 28. The ECU 28 is mainly composed of a microcomputer, and executes various engine control programs stored in a built-in ROM (storage medium) to thereby determine the fuel injection amount of the fuel injection valve 16 according to the engine operating state. The ignition timing of the spark plug 17 is controlled.

At this time, the ECU 28 calculates the engine rotational speed Ne as follows by executing routines for calculating the engine rotational speed shown in FIGS. 3 to 5 described later.
When the crank angle sensor 24 is normal, the ECU 28 calculates the engine rotation speed Ne based on the integrated value of the time interval of the output timing of the crank angle signal output from the crank angle sensor 24 for example every 30 CA.

  Specifically, the time interval between the previous and current 30CA interrupt timings (that is, the time interval between the previous and current crank angle signal output timings) is set to the current 30CA by performing a 30CA interrupt process at each crank angle signal output timing. It is calculated as time T30 (time required for the crankshaft 22 to rotate 30 CA).

Thereafter, the 30CA time T30 (n-2) of the previous two times, the 30CA time T30 (n-1) of the previous time and the current 30CA time T30 (n) are integrated, and the crankshaft 22 rotates in the normal state. A 90CA time T90, which is a time required to rotate a predetermined crank angle for speed calculation (for example, 90CA), is obtained.
T90 = T30 (n-2) + T30 (n-1) + T30 (n)

Thereafter, the engine rotational speed Ne [rpm] is calculated by the following equation using 90CA time T90.
Ne = 60 / (T90 × 4)

  Further, as shown in FIG. 2, when the crank angle sensor 24 is abnormal, the ECU 28 generates a pseudo start timing at the output timing (G2 edge timing) of the cam angle signal output from the cam angle sensor 27, for example, every 180CA. In addition, during the period from when the current cam angle signal is output until immediately before the next cam angle signal is output, the time interval T180 of the output timing of the cam angle signals that have already been output (previous and current cam angle signals). Functions as a pseudo start timing generating means for generating a pseudo start timing at a time interval T30 equally divided into six, and the crank counter is counted up for each pseudo start timing generated in this way.

  In this case, the time interval T30 of the pseudo activation timing is all equal from the pseudo activation timing at the time of output of the current cam angle signal to the pseudo activation timing immediately before the output of the next cam angle signal. The time interval between the pseudo start timing when the cam angle signal is output and the pseudo start timing immediately before it (hereinafter referred to as the “time interval of the pseudo start timing when the cam angle signal is output”) T30 (x) is the next cam angle signal. Therefore, there is a tendency to vary greatly compared to the time interval T30 of other pseudo activation timings. For example, during acceleration, the next cam angle signal output timing is advanced, so that the time interval T30 (x) of the pseudo activation timing when the cam angle signal is output is shortened. On the other hand, at the time of deceleration, the output timing of the next cam angle signal is delayed, so that the time interval T30 (x) of the pseudo activation timing at the time of cam angle signal output becomes longer.

  For this reason, when calculating the engine speed Ne based on the time interval T30 of the pseudo start timing generated based on the output signal (cam angle signal) of the cam angle sensor 27, the pseudo start timing at the time of cam angle signal output is calculated. When the time interval T30 (x) is used, there is a problem that the calculated value of the engine rotational speed Ne fluctuates significantly as shown by a two-dot chain line in FIG.

  As a countermeasure, when the crank angle sensor 24 is abnormal, the ECU 28 calculates the engine rotational speed Ne based on the integrated value of the time interval T30 of the pseudo activation timing. Excluding time interval T30 (x) of pseudo start timing when cam angle signal is output, engine time interval T30 of pseudo start timing other than time interval T30 (x) of pseudo start timing when cam angle signal is output is used. The rotational speed Ne is calculated.

  Specifically, the time interval between the previous and current 30 CA interrupt timings (that is, the time interval between the previous and current pseudo activation timings) is generated by the 30 CA interrupt process for each pseudo activation timing generated based on the cam angle signal output timing. ) Is calculated as the current 30CA time T30. In the case of 30CA interrupt processing at the time of cam angle signal output (30CA interrupt processing using the pseudo start timing at cam angle signal output as the interrupt timing), By setting the same value as the 30CA time T30 as the current 30CA time T30, the time interval T30 (x) of the pseudo activation timing when the cam angle signal is output is excluded.

Thereafter, the 30CA time T30 (n-2) of the previous two times, the 30CA time T30 (n-1) of the previous time, and the current 30CA time T30 (n) are integrated, and the crankshaft 22 rotates in an abnormal state. A 90CA time T90, which is a time required to rotate a predetermined crank angle for speed calculation (for example, 90CA), is obtained.
T90 = T30 (n-2) + T30 (n-1) + T30 (n)

Thereafter, the engine rotational speed Ne [rpm] is calculated by the following equation using 90CA time T90.
Ne = 60 / (T90 × 4)
The processing contents of the routines for calculating the engine speed shown in FIGS. 3 to 5 executed by the ECU 28 will be described below.

[Engine speed calculation main routine]
The engine speed calculation main routine shown in FIG. 3 is repeatedly executed at a predetermined cycle while the ECU 28 is powered on. When this routine is started, first, at step 101, whether or not the crank angle sensor 24 is abnormal is determined based on, for example, an abnormality diagnosis result of the crank angle sensor 24 by a crank angle sensor abnormality diagnosis routine (not shown). To do.

  If it is determined in step 101 that the crank angle sensor 24 is not abnormal (normal), the process proceeds to step 102, and a normal engine speed calculation routine shown in FIG. Thus, the engine speed Ne is calculated based on the integrated value of the time interval T30 of the output timing of the crank angle signal output from the crank angle sensor 24.

  On the other hand, if it is determined in step 101 that the crank angle sensor 24 is normal, the process proceeds to step 103, and an abnormal-time engine rotation speed calculation routine of FIG. Then, the engine speed Ne is calculated based on the integrated value of the time interval T30 of the pseudo activation timing generated based on the output signal (cam angle signal) of the cam angle sensor 27.

[Normal engine speed calculation routine]
The normal engine speed calculation routine (step 102 in FIG. 3) shown in FIG. 4 is repeatedly executed by a 30CA interrupt process at every output timing of the crank angle signal, and serves as normal speed calculation means in the claims. To play a role.

  When this routine is started, first, in step 201, the time interval between the previous and current 30CA interrupt timings (that is, the time interval between the previous and current crank angle signal output timings) is measured (calculated), and the measurement is performed. The value is the current 30 CA time T30.

Thereafter, the process proceeds to step 202, and the data of 30CA times T30 (n-2) to T30 (n) stored in the memory of the ECU 28 are respectively updated.
T30 (n-2) = T30 (n-1)
T30 (n-1) = T30 (n)
T30 (n) = T30

After this, the routine proceeds to step 203, where the previous 30CA time T30 (n-2), the previous 30CA time T30 (n-1) and the current 30CA time T30 (n) are added together to obtain the crankshaft. A 90 CA time T90, which is a time required for rotating a predetermined crank angle (for example, 90 CA) for calculating a normal rotation speed, is obtained.
T90 = T30 (n-2) + T30 (n-1) + T30 (n)

Thereafter, the routine proceeds to step 204, where the engine speed Ne is calculated by the following equation using the 90CA time T90.
Ne = 60 / (T90 × 4)

[Engine speed calculation routine during abnormal conditions]
The abnormal-time engine rotation speed calculation routine (step 103 in FIG. 3) shown in FIG. 5 is repeatedly executed by a 30 CA interrupt process for each pseudo activation timing generated based on the output timing of the cam angle signal. It functions as a means for calculating the abnormal rotation speed.

  When this routine is started, first, at step 301, it is determined whether or not the 30CA interrupt process at the time of cam angle signal output (30CA interrupt process using the pseudo start timing at the time of cam angle signal output as the interrupt timing). Determine.

  If it is determined in this step 301 that it is not a 30CA interrupt process at the time of cam angle signal output, the routine proceeds to step 302, where the time interval between the previous and current 30CA interrupt timing (that is, the previous and current pseudo start timings). Is measured (calculated), and the measured value is set as the current 30CA time T30.

  On the other hand, if it is determined in step 301 that the process is 30 CA interrupt processing at the time of cam angle signal output, the process proceeds to step 303 and the same value as the previous 30 CA time T30 is set as the current 30 CA time T30. Thus, the time interval T30 (x) of the pseudo activation timing when the cam angle signal is output is excluded.

Thereafter, the process proceeds to step 304, and the data of 30CA times T30 (n-2) to T30 (n) stored in the memory of the ECU 28 are respectively updated.
T30 (n-2) = T30 (n-1)
T30 (n-1) = T30 (n)
T30 (n) = T30

Thereafter, the process proceeds to step 305, where the previous 30CA time T30 (n-2), the previous 30CA time T30 (n-1), and the current 30CA time T30 (n) are added up to obtain the crankshaft. A 90 CA time T90, which is a time required for rotating a predetermined crank angle (for example, 90 CA) for calculating an abnormal rotation speed, is obtained.
T90 = T30 (n-2) + T30 (n-1) + T30 (n)

Thereafter, the process proceeds to step 306, and the engine speed Ne is calculated by the following equation using the 90CA time T90.
Ne = 60 / (T90 × 4)

  In the first embodiment described above, when the crank angle sensor 24 is abnormal, the pseudo start timing is generated at the output timing of the cam angle signal output from the cam angle sensor 27 and the current cam angle signal is output. During the period immediately before the next cam angle signal is output, a pseudo start is performed at a time interval T30 obtained by equally dividing the time interval T180 of the output timing of the already output cam angle signals (previous and current cam angle signals) into six. Generate timing.

  When the crank angle sensor 24 is abnormal, the engine speed Ne is calculated based on the integrated value of the time interval T30 of the pseudo start timing. At this time, the cam angle signal is output in the time interval T30 of the pseudo start timing. The engine speed Ne is calculated using the time interval T30 of the pseudo start timing other than the time interval T30 (x) of the pseudo start timing when the cam angle signal is output, excluding the time interval T30 (x) of the pseudo start timing Therefore, as indicated by the solid line in FIG. 6, the engine speed Ne can be calculated without being affected by the fluctuation of the time interval T30 (x) of the pseudo start timing when the cam angle signal is output. The fluctuation of the calculated value of the engine speed Ne can be suppressed.

  In the first embodiment, the predetermined crank angle for calculating the normal rotation speed and the predetermined crank angle for calculating the abnormal rotation speed are set to 90 CA, and the engine rotation speed Ne is calculated using the 90 CA time T90. However, the present invention is not limited to this, and the predetermined crank angle for calculating the normal rotation speed and the predetermined crank angle for calculating the abnormal rotation speed may be appropriately changed. For example, the predetermined crank angle for calculating the normal rotation speed The predetermined crank angle for calculating the angle and the abnormal rotation speed is set to any one of 180CA, 360CA, 720CA, and the like, and the engine rotation speed Ne using any of 180CA time T180, 360CA time T360, 720CA time T720, etc. May be calculated.

  Next, Embodiment 2 of the present invention will be described with reference to FIGS. However, description of substantially the same parts as those in the first embodiment will be omitted or simplified, and different parts from the first embodiment will be mainly described.

  In the second embodiment, when the crank angle sensor 24 is normal, as in the first embodiment, the time interval T30 of the output timing of the crank angle signal is integrated, and the crankshaft 22 is a predetermined value for calculating the normal rotation speed. A 90CA time T90 that is a time required for rotating the crank angle (for example, 90CA) is obtained, and the engine speed Ne is calculated using the 90CA time T90.

  On the other hand, when the crank angle sensor 24 is abnormal, the ECU 28 executes an abnormal-time engine rotation speed calculation routine shown in FIG. A 360 CA time T360, which is a time required to rotate a predetermined crank angle for calculation (eg, 360 CA), is obtained, and the engine speed Ne is calculated using the 360 CA time T360. That is, the predetermined crank angle (for example, 360 CA) for calculating the abnormal rotation speed is set to be larger than the predetermined crank angle (for example, 90 CA) for calculating the normal rotation speed.

  The abnormality engine speed calculation routine of FIG. 7 is obtained by changing the processing of steps 304 to 306 of the routine of FIG. 5 described in the first embodiment to the processing of steps 304a to 306a, and other steps. This processing is the same as in FIG.

  In the abnormal engine speed calculation routine of FIG. 7, if it is determined that it is not the 30 CA interrupt process when the cam angle signal is output, the previous and current 30 CA interrupt timing time intervals (that is, the previous and current pseudo start timings) are determined. (Time interval) is measured (calculated), and the measured value is set as the current 30CA time T30. If it is determined that the 30CA interrupt processing is performed when the cam angle signal is output, the same value as the previous 30CA time T30 is obtained. Is set to the current 30CA time T30, the time interval T30 (x) of the pseudo activation timing when the cam angle signal is output is excluded (steps 301 to 303).

Thereafter, the process proceeds to step 304a, and the data of 30CA times T30 (n-11) to T30 (n) stored in the memory of the ECU 28 are respectively updated.
T30 (n-11) = T30 (n-10)
T30 (n-10) = T30 (n-9)
T30 (n-9) = T30 (n-8)
T30 (n-8) = T30 (n-7)
T30 (n-7) = T30 (n-6)
T30 (n-6) = T30 (n-5)
T30 (n-5) = T30 (n-4)
T30 (n-4) = T30 (n-3)
T30 (n-3) = T30 (n-2)
T30 (n-2) = T30 (n-1)
T30 (n-1) = T30 (n)
T30 (n) = T30

  Thereafter, the process proceeds to step 305a, where the accumulated time from the 30 CA time T30 (n-11) 11 times before to the current 30CA time T30 (n) is added, and from a predetermined crank angle (for example, 90 CA) for calculating the normal rotation speed. 360 CA time T360, which is a time required for the crankshaft 22 to rotate at a predetermined crank angle (for example, 360 CA) for calculating the abnormal rotation speed, is also obtained.

T360 = T30 (n-11) + T30 (n-10) + ... + T30 (n-1) + T30 (n)
Thereafter, the process proceeds to step 306a, and the engine rotational speed Ne is calculated by the following equation using 360 CA time T360.
Ne = 60 / T360

  In the second embodiment described above, when the crank angle sensor 24 is abnormal, the time interval T30 of the pseudo activation timing is integrated, and the abnormal rotation speed larger than a predetermined crank angle (for example, 90 CA) for calculating the normal rotation speed. A 360 CA time T360 that is a time required for the crankshaft 22 to rotate at a predetermined crank angle for calculation (for example, 360 CA) is obtained, and the engine speed Ne is calculated using the 360 CA time T360.

  During the fail safe in which the engine speed Ne is calculated based on the time interval T30 of the pseudo start timing when the crank angle sensor 24 is abnormal, it is not necessary to detect the fluctuation of the engine speed Ne sensitively and precisely control it. 360 CA time T360, which is a time required for the crankshaft 22 to rotate at a predetermined crank angle for abnormal rotation speed calculation (for example, 360 CA) larger than a predetermined crank angle for calculation of normal rotation speed (for example, 90 CA), is obtained. By calculating the engine rotational speed Ne using this 360 CA time T360, fluctuations in the calculated value of the engine rotational speed Ne can be effectively suppressed as shown by the solid line in FIG.

  In the second embodiment, the predetermined crank angle for calculating the abnormal rotation speed is set to 360 CA. However, the present invention is not limited to this, and the predetermined crank angle for calculating the abnormal rotation speed may be appropriately changed. For example, the predetermined crank angle for calculating the abnormal rotation speed may be set to any one of 180CA, 720CA, etc. In short, the predetermined crank angle for calculating the abnormal rotation speed is used for calculating the normal rotation speed. What is necessary is just to make it larger than a predetermined crank angle.

  Next, Embodiment 3 of the present invention will be described with reference to FIG. However, description of substantially the same parts as those of the second embodiment will be omitted or simplified, and different parts from the second embodiment will be mainly described.

  In the second embodiment, when the crank angle sensor 24 is abnormal, the time interval T30 of the pseudo activation timing is actually measured, and the measured value of the time interval T30 of the pseudo activation timing is integrated to obtain 360 CA time T360 (pseudo activation timing). In the third embodiment, when the crank angle sensor 24 is abnormal, the time interval T30 (equally divided into six time intervals T180 of the cam angle signal output timing) is obtained. = Time interval T30 of pseudo activation timing) is integrated to obtain 360 CA time T360 (integrated value of time interval T30 of pseudo activation timing).

  Specifically, as shown in FIG. 9, when the crank angle counter ccrnk = 14, the time interval T180a of the output timing of the cam angle signal two times before (the timing of the effective cam edge of the G2 signal) is set. A value obtained by integrating six time intervals T30a divided into six (T30a × 6 = T180a × 6/6) and a time interval T30b obtained by dividing the time interval T180b of the output timing of the previous cam angle signal into six equal to six The 360 CA time T360 is obtained by integrating the two integrated values (T30b × 6 = T180b × 6/6).

T360 = (T180a × 6/6) + (T180b × 6/6)
Using this 360 CA time T360, the engine speed Ne is calculated by the following equation.
Ne = 60 / T360

  (2) When the crank angle counter ccrnk = 15, a value obtained by integrating five time intervals T30a obtained by dividing the time interval T180a of the output timing of the cam angle signal two times before by six (T30a × 5 = T180a × 5) / 6), a value obtained by integrating six time intervals T30b obtained by dividing the time interval T180b of the output timing of the previous cam angle signal by six (T30b × 6 = T180b × 6/6), and the cam angle of this time The 360 CA time T360 is obtained by integrating the value of the time interval T30c (T30c = T180c × 1/6) obtained by dividing the signal output timing time interval T180c into six equal parts.

T360 = (T180a × 5/6) + (T180b × 6/6) + (T180c × 1/6)
Using this 360 CA time T360, the engine speed Ne is calculated by the following equation.
Ne = 60 / T360

  (3) When the crank angle counter ccrnk = 16, a value obtained by integrating four time intervals T30a obtained by dividing the time interval T180a of the output timing of the cam angle signal two times before by six (T30a × 4 = T180a × 4) / 6), a value obtained by integrating six time intervals T30b obtained by dividing the time interval T180b of the output timing of the previous cam angle signal by six (T30b × 6 = T180b × 6/6), and the cam angle of this time A value obtained by integrating two time intervals T30c obtained by dividing the signal output timing time interval T180c into six equal parts (T30c × 2 = T180c × 2/6) is integrated to obtain 360 CA time T360.

T360 = (T180a × 4/6) + (T180b × 6/6) + (T180c × 2/6)
Using this 360 CA time T360, the engine speed Ne is calculated by the following equation.
Ne = 60 / T360

  In the third embodiment described above, when the crank angle sensor 24 is abnormal, the time interval T30 (= the time interval T30 of the pseudo start timing) obtained by equally dividing the time interval T180 of the cam angle signal output timing into six is integrated. 360 CA time T360 (the integrated value of the time interval T30 of the pseudo activation timing) is obtained, so that it is not necessary to actually measure the time interval T30 of the pseudo activation timing, and 360 CA time T360 (the time interval of the pseudo activation timing). It is possible to simplify the arithmetic processing when obtaining the integrated value of T30.

  In each of the first to third embodiments, the pseudo start timing is generated at a time interval obtained by equally dividing the time interval of the output timing of the previous cam angle signal and the current cam angle signal into a plurality of times. For example, the pseudo start timing is generated at a time interval obtained by equally dividing the time interval of the output timing of the cam angle signal two times before (two times before) and the previous time (one time before), or Alternatively, the pseudo activation timing may be generated at a time interval obtained by equally dividing the time interval between the output timing of the previous cam angle signal (two times before) and the current cam angle signal into a plurality of times.

  Further, the present invention is not limited to the intake port injection type engine as shown in FIG. 1, and includes an in-cylinder injection type engine, and a fuel injection valve for intake port injection and a fuel injection valve for in-cylinder injection. It can also be applied to dual-injection engines.

  Furthermore, the present invention is not limited to a vehicle using only an engine as a power source, and may be applied to a hybrid vehicle using both an engine and a motor as power sources.

  DESCRIPTION OF SYMBOLS 11 ... Engine (internal combustion engine), 13 ... Intake pipe, 14 ... Throttle valve, 16 ... Fuel injection valve, 17 ... Spark plug, 19 ... Exhaust pipe, 22 ... Crankshaft, 24 ... Crank angle sensor, 25 ... Camshaft, 27 ... cam angle sensor, 28 ... ECU (normal rotation speed calculation means, pseudo start timing generation means, abnormal rotation speed calculation means)

Claims (3)

FAILURE OF INTERNAL COMBUSTION ENGINE PROVIDED WITH CRANK ANGLE SENSOR FOR OUTPUT CRANK ANGLE SIGNAL SYNCHRONIZING WITH CRANK SHAFT OF INTERNAL COMBUSTION ENGINE AND CAM ANGLE SENSOR FOR SYNCHRONIZING CAM SHAFT SIGNAL WITH SYNCHRONIZATION In safe control equipment,
A normal rotation speed calculation means for calculating the rotation speed of the internal combustion engine based on the time interval of the output timing of the crank angle signal when the crank angle sensor is normal;
When the crank angle sensor is abnormal, a pseudo start timing is generated at the output timing of the cam angle signal, and a period from when the cam angle signal is output to immediately before the next cam angle signal is output is already output. Pseudo startup timing generation means for generating pseudo startup timing at a time interval equally divided into a plurality of time intervals of the output timing of the cam angle signal;
An abnormal-time rotational speed calculating means for calculating the rotational speed of the internal combustion engine based on an integrated value of the time interval of the pseudo start timing when the crank angle sensor is abnormal,
The abnormal-time rotation speed calculation means calculates the rotation speed of the internal combustion engine based on the integrated value of the time interval of the pseudo start timing, and outputs the cam angle signal in the time interval of the pseudo start timing. A fail-safe control apparatus for an internal combustion engine, wherein the rotational speed of the internal combustion engine is calculated by excluding a time interval between the pseudo start timing and the immediately preceding pseudo start timing. The abnormal time rotation speed calculating means integrates time intervals obtained by equally dividing the time interval of the output timing of the cam angle signal into a plurality of times to obtain an integrated value of the time interval of the pseudo start timing. The fail-safe control device for an internal combustion engine according to claim 1 . The normal rotation speed calculation means is a time required for the internal combustion engine to rotate a predetermined crank angle for calculating a normal rotation speed based on a time interval of output timing of the crank angle signal when the crank angle sensor is normal. And calculating the rotation speed of the internal combustion engine based on the time required to rotate the predetermined crank angle for calculating the normal rotation speed ,
The abnormal rotation speed calculation means calculates a time required for the internal combustion engine to rotate a predetermined crank angle for calculating the abnormal rotation speed based on the time interval of the pseudo start timing, and calculates the abnormal rotation speed. The rotational speed of the internal combustion engine is calculated based on the time required to rotate the predetermined crank angle, and the predetermined crank angle for calculating the abnormal speed is larger than the predetermined crank angle for calculating the normal speed. The fail-safe control device for an internal combustion engine according to claim 1 or 2 , characterized in that:

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