JP2850583B2 - Device for detecting decrease in rotational speed of internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art An internal combustion engine for a vehicle generally has a mechanism for stopping the supply of fuel during a predetermined deceleration operation (see Japanese Patent Application Laid-Open No. 63-113137) .
Further, in the engine equipped with such a fuel supply stop mechanism, a so-called deceleration shock occurs due to a sudden increase in torque when fuel supply is restarted. Therefore, in order to mitigate this, the number of cylinders for restarting fuel supply is increased stepwise. (Partial cylinder fuel supply resumption control), there is one in which ignition timing is retarded. However, when the above-described control is executed when the clutch is disengaged or when the rotational speed suddenly decreases in a neutral state, there is a risk of stalling, so that the fuel supply to all cylinders is restarted at once, or the ignition timing is retarded. In some cases, control is switched such that control is stopped.

[0003]

However, when the control is changed in accordance with the deceleration as described above, the detected value of the rotational speed varies due to the fluctuation of the rotation of the camshaft. When driving
In the variation ΔN of the rotational speed obtained in the cycle of about 100 ms, the accuracy of the determination of the rapid rotation drop is poor, and even when the rotation is gently reduced, it is determined that the rapid rotation has dropped and the fuel supply for all the cylinders is simultaneously restarted. In some cases, the retard control was stopped or the deceleration shock could not be reduced.

The present invention has been made in view of such a conventional problem, and provides a rotational speed reduction detecting device capable of accurately detecting a rapid decrease in the rotational speed which leads to a stall of an internal combustion engine. The purpose is to:

[0005]

As shown in FIG. 1, the present invention provides a rotational speed detecting means for detecting the rotational speed of an internal combustion engine at predetermined intervals, and a method for detecting the rotational speed of the internal combustion engine at predetermined intervals. Reduction speed calculation means for calculating the detected reduction speed of the rotation speed at each of the predetermined periods; and reduction speed average value calculation means for calculating the average value of the previously calculated reduction speed and the latest calculated reduction speed. And a counting means for comparing the calculated average value of the decreasing speed with a set value and counting the number of times when the set value is exceeded, and the average value of the decreasing speed is calculated while performing a predetermined number of continuous calculations. And a sudden decrease determining means for judging that the rotational speed is sharply decreased when the number of times exceeding the set value reaches the set number of times.

[0006] The average value of the computed reduced speed, before
Serial while performing the calculation of the successive predetermined times, when it becomes the set value smaller than the second setting consecutive two or more times lower than values, and configured to include a reset means for resetting the measurement by said counting means Is also good.

[0007]

The rotation speed is calculated by calculating the reduction speed of the latest detected rotation speed with respect to the rotation speed detected a predetermined number of times before, and calculating the average value of the previously calculated reduction speed and the latest calculated reduction speed. Calculation is performed every time, and the sudden deceleration is determined at a frequency at which the average value exceeds the set value. Therefore, only when the rotational speed continuously decreases suddenly, it is determined that the rapid deceleration is performed. A rapid decrease in rotation is not determined to be a sudden deceleration that results in a stall. Therefore, the detection accuracy is increased, and control for speeding up the recovery of the engine output due to erroneous determination is performed, thereby preventing occurrence of a deceleration shock.

Further, when the average value of the computed reduced rotational speed, while performing the predetermined times of operation with the continuous, becomes twice or more in succession below the set value smaller than the second set value, The detection accuracy can be further improved by determining that the rapid decrease in rotation has been once stopped and resetting the measurement by the counting means and redoing the determination.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 2 shows a hardware configuration. The intake passage 2 of the internal combustion engine 1 is provided with an air cleaner 3, an air flow meter 4 for detecting an 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 degree is provided. Further, 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 energization of an ignition circuit 11 connected to the primary side of the ignition coil 10, This high voltage is applied to the ignition 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 rotation speed detecting means for detecting the engine rotation speed is provided at one end of the camshaft (not shown). Along with the throttle valve opening signal from the throttle sensor 8 and the like, it is input to a control circuit 14 containing a microcomputer. And
The control circuit 14 controls the fuel injection amount from the fuel injection valve 6 and performs the ignition control and the like according to the operating state detected based on the various signals. In addition, when the throttle valve 5 closes at a predetermined speed or more during a deceleration operation and when conditions such as the engine speed at the start of deceleration are equal to or higher than a predetermined value, 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 equal to or less than a predetermined value, control is performed to gradually increase the number of cylinders for restarting fuel supply and to retard the ignition timing in order to alleviate the deceleration shock. However, if the rotation speed drops rapidly, the control is stopped, fuel supply is restarted simultaneously for all cylinders, and the ignition timing retard control is stopped. Then, the control according to the present invention is used to determine the decrease in the rotation speed at the time of deceleration for switching the control.

[0011] The following is a judgment of the decrease in the rotational speed during the deceleration.
Of fuel injection control and ignition timing control during deceleration including
The chin will be described according to the flowchart shown in FIG.
You. This routine is executed at predetermined intervals, for example, every 10 milliseconds.
It is. Step (S in the figure, the same applies hereinafter) In step 1,
The rotational speed N detected a predetermined number of times (for example, 10 times before) _-Ten
Deceleration ΔN with respect to the latest rotation speed N detected this time
(= N_-Ten −N). This step 1 function
It constitutes a decrease speed calculating means.

In step 2, it is determined whether the calculated deceleration is a positive value. When the value is a positive value, the speed is decelerating. When the speed is not decelerating, the process proceeds to step 3 and the subsequent steps, and the counter DNCNT counts the number of times the speed is reduced.
R, a counter KYUCNT for counting the number of times when the rotation drop is large, a flag FSD for canceling the partial-cylinder fuel supply restart control, and a flag FSD2 for canceling the ignition timing retard control are sequentially cleared to 0 to determine the sudden drop in the rotation. Reset.

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

In step 9, once DN> DNKYUP
Then, the flag FBLT, which is set to 1 when DN ≦ DNKYUP, 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 has exceeded a set value is compared with a set number of times CNTKYU. Then, when it is determined that KYUCNT ≧ CNTKYU, it is determined that the rotational speed is rapidly reduced to such a degree as to cause a stall, and the process proceeds to step 12, where the flag FSD and the flag FSD2 are both set to 1, and
The partial cylinder fuel supply restart control and the ignition timing retard control during fuel supply stoppage executed in another routine are canceled. The functions of these steps 11 and 12 constitute a sudden drop determination means.

Finally, at step 13, the current decreasing speed ΔN
ΔN _-1 to make the calculated value of
Set to. In step 11, KYUCNT <
If it is determined to be CNTKYU, proceed to step 14,
The value of the counter DNCNTR is a predetermined number of times (for example, 10 times)
It is determined whether or not the above has been achieved. If it is less than the predetermined number of times, the process proceeds to step 13 to continue the determination of the sudden decrease in the rotation.

If it is determined in step 7 that DN≤DNKYUP, the routine proceeds to step 15, where it is determined whether or not the counter DNCNTR of the number of times of reduction speed calculation has been cleared to 0. Proceed to the subsequent steps to reset the determination of the rapid decrease in rotation. If it is determined in step 15 that the counter DNCNTR has not been cleared to 0, the process proceeds to step 16, in which the average decrease speed DN is compared with a second set value DNKYUM set to a value smaller than the set value DNKYUP. . Then, DN ≧ DNK
If YUM, proceed to step 10, but DN <DNKYU
If M, the process proceeds to step 17 to determine the value of the aforementioned flag FBLT. If the value is cleared to 0, the process proceeds to step 18 to set the flag FBLT to 1 and then to step 10, but the flag FBLT is set to 1. If so, the process proceeds to step 3 and the subsequent steps, and the determination of the rapid decrease in rotation is reset. That is, the continuous
If the number of times continuously becomes less than the second set value DNKYUM two or more times while performing the predetermined number of calculations (for example, ten times), it is determined that the rapid decrease in the rotation speed has once been settled, and the value suddenly decreases. To make the judgment again.

According to the method for judging a sudden decrease in rotation, as shown in FIG. 4, a decrease speed in a relatively long cycle is calculated, and the calculation cycle itself is shortened to compare the latest calculation value with the previous calculation value. By judging a sudden decrease in rotation at a frequency exceeding the set value while comparing the average value with the set value, only when the rotational speed continuously decreases suddenly, it is determined that the speed is suddenly reduced, and the rotational speed is determined. It is possible to prevent a temporary sudden decrease in rotation due to the fluctuation from being determined as a sudden deceleration that leads to a stall. Therefore, it is possible to prevent the occurrence of a deceleration shock by erroneously determining the slow deceleration as the rapid deceleration, stopping the partial cylinder fuel supply restart control, the ignition timing retard control, and the like, and performing the control to accelerate the recovery of the engine output. .

Further, when the average value of the reduced rotation speed continues to be small, the determination is redone by resetting, so that the detection accuracy is further improved.

[0019]

As described above, according to the present invention, the reduced rotation speed at relatively long intervals is calculated for each short cycle, and the averaged value is compared with the set value. When the frequency exceeding the set value is equal to or more than a predetermined value, it is determined that the engine rotational speed is sharply reduced. Thus, it is possible to prevent a deceleration shock due to erroneous control that accelerates recovery of the engine output.

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

[Brief description of the drawings]

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

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

FIG. 3 is a flowchart showing a routine for determining a rapid 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 rotational speed of the embodiment; 1 internal combustion engine 13 rotational speed sensor 14 control circuit

Claims (2)

(57) [Claims] A rotational speed detecting means for detecting a rotational speed of the internal combustion engine at predetermined intervals; and calculating a latest decrease speed of the rotational speed with respect to the rotational speed detected at a predetermined time interval at each of the predetermined intervals. A decreasing speed calculating means for calculating the average value of the previously calculated decreasing speed and the latest calculated decreasing speed; and comparing the calculated average value of the decreasing speed with the set value. A counting means for counting the number of times when the set value is exceeded, and a rotation speed when the number of times that the average value of the decreasing speed exceeds the set value reaches the set number of times while performing a predetermined number of continuous calculations. And a sudden decrease judging means for judging a sudden decrease in the rotational speed of the internal combustion engine. 2. The method according to claim 1, wherein the calculated average value of the decreasing speed is equal to the continuous value.
While performing the predetermined times of operation, characterized in that when it is more than 2 times in succession below the set value smaller than the second set value, which is configured to include a reset means for resetting the measurement by said counting means The apparatus for detecting a decrease in the rotational speed of an internal combustion engine according to claim 1, wherein: