JPH0533703A - Rotating speed reduction detection device for internal combustion engine - Google Patents

Abstract

PURPOSE:To detect with high precision the rapid delay of rotating speed which would lead to a stall of the internal combustion engine. CONSTITUTION:Detection is made of the rotating speed N of the internal combustion engine with respect to each specified period (10mmsec.), and calculation is made, per said specified period, of the reduction speed N between a now value and a specified-time (100mmsec) preceding value. Further, calculation is made of an average value DN of the newest calculated reduction speed N and the previously calculated reduction speed value N-1. When this average value DN appears at a set frequency (e.g. 7 times) during a specified number (e.g. 10 times) of calculations, it is decided that the rotating speed is being rapidly decreased. This enables preventing the occurrence of a speed-reduction shock resulting from expediting the recovery of the engine output due to an erroneous decision of a temporary rapid delay in rotation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for detecting a sudden decrease in the rotation speed of an internal combustion engine.

[0002]

2. Description of the Related Art An internal combustion engine for a vehicle is generally provided with a mechanism for stopping fuel supply during a predetermined deceleration operation (see Japanese Patent Laid-Open No. 58-20374). Further, in the case where such a fuel supply stop mechanism is provided, a so-called deceleration shock occurs due to a rapid increase in torque when the fuel supply is restarted, so the number of cylinders for restarting fuel supply may be increased stepwise to mitigate this. (Partial cylinder fuel supply resumption control) and ignition timing retard control are available. However, when the clutch is disengaged or in a neutral state where the rotation speed sharply decreases, executing the control may cause a stall, so that fuel supply to all cylinders may be restarted at once, or ignition timing may be retarded. Some control is switched so as to stop the control.

[0003]

However, in the case of changing the control according to the deceleration as described above, the detected value of the rotation speed varies due to the fluctuation of the rotation of the camshaft. When driving
With the amount of change in rotational speed ΔN obtained in the cycle of about 100 ms, the accuracy of the sudden rotation drop is poor, and even if the rotation speed falls slowly, it is determined that there is a sudden rotation drop and fuel supply is restarted for all cylinders at the same time. Sometimes the retard control was stopped and the deceleration shock could not be reduced.

The present invention has been made in view of the above-mentioned conventional problems, and provides a rotation speed decrease detecting device capable of accurately detecting a sharp decrease in the rotation speed leading to a stall of an internal combustion engine. The purpose is to

[0005]

Therefore, according to the present invention, as shown in FIG. 1, the rotation speed detecting means for detecting the rotation speed of the internal combustion engine at every predetermined cycle and the latest rotation speed for the rotation speed detected a predetermined number of times before. Decrease speed calculation means for calculating the decrease speed of the rotation speed detected at every predetermined cycle, and decrease speed average value calculation means for calculating an average value of the previously calculated decrease speed and the latest calculated decrease speed. And a counting means for comparing the calculated average value of the decreasing speed with a set value and measuring the number of times when the set value is exceeded, and the average value of the decreasing speed during the continuous predetermined number of operations. And a rapid decrease determination means for determining a rapid decrease in the rotation speed when the number of times of exceeding the set value reaches the set number of times.

Further, when the average value of the calculated deceleration speeds is less than the second set value smaller than the set value twice or more during the period in which the state below the set value is held, the counting means is provided. It may be configured to include a resetting unit that resets the measurement by.

[0007]

Operation: The decrease speed of the latest detected rotation speed with respect to the rotation speed detected a predetermined number of times is calculated, and the average value of the previously calculated decrease speed and the latest calculated decrease speed is calculated. It is calculated for each time, and the rapid deceleration is determined with the frequency that the average value exceeds the set value. Therefore, only when the rotation speed continuously sharply decreases, the determination of the rapid deceleration is made, and the temporary deceleration due to the rotation fluctuation is made. A sudden decrease in rotation is not judged as a sudden deceleration that leads to a stall. Therefore, it is possible to prevent the occurrence of deceleration shock due to the increased detection accuracy and the control that accelerates the recovery of the engine output due to an erroneous determination.

Further, when the average value of the calculated reduced rotational speeds is less than the second set value smaller than the set value twice or more during the period in which the state of being equal to or less than the set value is maintained, it is suddenly increased. The detection accuracy can be further improved by determining that the decrease in rotation has once been settled, resetting the measurement by the counting means, and making the determination again.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 shows the hardware configuration. The intake passage 2 of the internal combustion engine 1 is provided with an air cleaner 3, an air flow meter for detecting the intake air flow rate, a throttle valve 5, a fuel injection valve 6, and an intake valve 7 in this order from the upstream side, and is connected to the throttle valve 5. A throttle sensor 8 for detecting the valve opening is provided. An ignition plug 9 is provided in the combustion chamber of each cylinder, and a high voltage is generated on the secondary side of the ignition coil 10 by cutting off the power supply to the ignition circuit 11 connected to the primary side of the ignition coil 10. This high voltage is applied to the spark plug 9 of the cylinder at the ignition timing via the distributor 12 to discharge between the electrodes and ignite.

Further, a rotation speed sensor 13 as a rotation speed detecting means for detecting the engine rotation speed is provided at one end of a cam shaft (not shown), and its rotation speed detection signal is an intake air flow rate signal from the air flow meter 4 or The throttle valve opening signal from the throttle sensor 8 and the like are input to a control circuit 14 having a built-in microcomputer. And
The control circuit 14 controls the fuel injection amount from the fuel injection valve 6 and the ignition control according to the operating state detected based on the various signals. Further, during deceleration operation in which the throttle valve 5 is closed at a speed equal to or higher than a predetermined speed, and when conditions such as the engine rotation speed at the start of deceleration being a predetermined value or higher are satisfied, the supply of fuel to the engine is stopped. In addition to performing fuel supply stop control, if the decrease in rotation speed during deceleration is below a predetermined level, gradually increase the number of cylinders that restart fuel supply to mitigate the deceleration shock, and also perform control to retard the ignition timing. However, when the rotation speed drops sharply, the control is stopped, fuel supply is restarted simultaneously for all cylinders, and ignition retard control is stopped. Then, the determination according to the present invention as to whether or not the rotational speed is reduced during deceleration for switching the control is performed.

The following is a determination of the decrease in the rotation speed during deceleration.
Of fuel injection control and ignition timing control during deceleration including disconnection
Chin will be explained according to the flowchart shown in FIG.
It This routine is executed every predetermined cycle, for example, every 10 mm seconds.
Be done. Step (denoted as S in the figure. The same applies hereinafter) In 1,
Rotational speed N detected a predetermined number of times before (for example, 10 times before) _-Ten
Deceleration ΔN for the latest rotation speed N detected this time
(= N_-Ten -N) is calculated. The function of this step 1
A deceleration speed calculation means is configured.

In step 2, it is determined whether the calculated deceleration is a positive value. When the positive value is the deceleration time, and when it is not the deceleration time, the counter DNCNT that proceeds to step 3 and thereafter and counts the number of reduction speed calculations
R, a counter KYUCNT that counts the number of times when the rotation speed is large, a flag FSD that cancels the partial cylinder fuel supply resumption control, and a flag FSD2 that cancels the ignition timing retard control are sequentially cleared to 0 to determine the rapid rotation speed decrease. Reset.

When it is determined in step 2 that the vehicle is decelerating, the routine proceeds to step 6, where the deceleration ΔN calculated in step 1
And an average value DN of the previously calculated deceleration ΔN ₋₁ is calculated. The function of step 6 constitutes the deceleration average value calculation means. In step 7, the deceleration average value DN calculated in step 6 is compared with the set value DNKYUP.
If DN> DNKYUP, step 8
Then, the process proceeds to and the counter KYUCNT is incremented. The function of this step 8 constitutes the counting means.

In step 9, DN> DNKYUP once
Then, when DN ≦ DNKYUP, the flag FBLT which is set to 1 is cleared to 0. In step 10, the counter DNCNTR is incremented. In step 11, the number of times that the rotation decrease measured by the counter KYUCNT exceeds the set value is compared with the set number of times CNTKYU. When it is determined that KYUCNT ≧ CNTKYU, it is determined that the rotation speed is drastically decreased to the extent of stalling, and the routine proceeds to step 12, where both the flag FSD and the flag FSD2 are set to 1,
The partial-cylinder fuel supply resuming control and the ignition timing retarding control while the fuel supply is stopped, which are executed in another routine, are canceled. The functions of step 11 and step 12 constitute a sudden drop determination means.

Finally, in step 13, the current decreasing speed ΔN
Since the calculated value of is the previous value for the next calculation, ΔN _-1
Set to. In step 11, KYUCNT <
If it is determined to be CNTKYU, proceed to step 14,
The value of the counter DNCNTR is predetermined times (for example, 10 times)
It is determined whether or not the above. If it is less than the predetermined number of times, the routine proceeds to step 13 to continue the determination of the rapid rotation decrease, but if it is more than the predetermined number of times, the routine proceeds to step 3 and thereafter to reset the determination of the rapid rotation reduction.

When it is judged in the step 7 that DN ≦ DNKYUP, the routine proceeds to step 15, where it is judged whether or not the counter DNCNTR of the deceleration calculation number is cleared to 0, and if it is cleared, the step 3 is carried out. The procedure goes to the subsequent steps to reset the judgment of the sudden decrease in rotation. When it is determined in step 15 that the counter DNCNTR has not been cleared to 0, the process proceeds to step 16 and the deceleration average value DN is compared with the second set value DNKYUM set to a value smaller than the set value DNKYUP. . And DN ≧ DNK
If YUM, proceed to step 10, but DN <DNKYU
If it is M, the process proceeds to step 17 to judge the value of the above-mentioned flag FBLT, and if it is cleared to 0, the process proceeds to step 18 to set the flag FBLT to 1 and then to step 10, but it is set to 1. If so, the process proceeds to step 3 and subsequent steps to reset the determination of the rapid rotation drop. That is, the decrease speed average value DN is less than the second set value DNKYUM during the period in which the state in which the decrease speed average value DN is equal to or less than the first set value DNKYUP is maintained.
If the number of rotations is equal to or more than that, it is determined that the sudden decrease in the rotation speed has once been stopped, and the determination of the sudden decrease is performed again.

According to the determination method of such a sudden decrease in rotation, as shown in FIG. 4, the decreasing speed in a relatively long cycle is calculated, and the calculation cycle itself is shortened to calculate the latest calculated value and the previous calculated value. By comparing the average value with the set value and determining a sudden decrease in rotation with a frequency that exceeds the set value, only when the rotation speed continuously sharply decreases, it is determined that there is rapid deceleration, and the rotation speed decreases. It is possible to prevent the temporary deceleration of the rotation due to the fluctuation from being determined as the sudden deceleration that leads to the stall. Therefore, it is possible to prevent the deceleration shock from occurring by erroneously determining the slow deceleration as the sudden deceleration, stopping the partial cylinder fuel supply resumption control, the ignition timing retard control, etc., and performing the control to accelerate the recovery of the engine output. .

Further, when the average value of the reduced rotational speeds continues to be small, the determination is performed again by resetting, so that the detection accuracy is further enhanced.

[0019]

As described above, according to the present invention, the decreasing rotational speed at a relatively long interval is calculated for each short period, and the averaged value is compared with the set value. Since it was determined that the engine rotation speed drastically decreased when the frequency of exceeding the set value was more than a predetermined value, it is possible to erroneously determine a momentary sharp drop in rotation due to rotation fluctuation as a continuous sharp drop. Therefore, deceleration shock due to erroneous control that speeds up recovery of engine output can be prevented.

Further, if the judgment is reset when the state in which the decrease in the rotation speed is small continues, the detection accuracy can be further improved.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration and function of the present invention.

FIG. 2 is a diagram showing a system configuration of an embodiment of the present invention.

FIG. 3 is a flowchart showing a routine for determining a sudden decrease in rotation speed according to the embodiment.

FIG. 4 is a time chart showing a change in each state quantity at the time of a rapid decrease in the rotation speed of the above-described embodiment 1. Internal combustion engine 13 Rotation speed sensor 14 Control circuit

Claims (2)

[Claims] 1. A rotation speed detecting means for detecting a rotation speed of an internal combustion engine at every predetermined cycle, and a reduction speed of the latest detected rotation speed with respect to a rotation speed detected a predetermined number of times is calculated at each predetermined cycle. Decrease speed calculation means for calculating the average value of the previously calculated decrease speed and the latest calculated decrease speed, and the calculated decrease speed average value is compared with the set value. Counting means for counting the number of times when the set value is exceeded, and rotation speed when the number of times the average value of the decreasing speed exceeds the set value reaches the set number while performing a predetermined number of consecutive calculations. And a rapid decrease determination means for determining a rapid decrease in the internal combustion engine. 2. The counting means when the average value of the calculated deceleration values is less than a second set value smaller than the set value twice or more during a period in which the state is kept below the set value. 2. The rotational speed reduction detecting device for an internal combustion engine according to claim 1, wherein the detecting device is configured to include reset means for resetting the measurement by.