JPH0686836B2 - Electronic internal combustion engine controller - Google Patents

Description

Description: TECHNICAL FIELD The present invention detects an average flow rate of air flowing into an automobile engine or the like by processing an output pulse of a Karman vortex type air flow rate sensor to detect fuel injection control and ignition timing control. The present invention relates to an electronic internal-combustion-engine control device to be performed.

Conventional technology and problems Generally, in an internal combustion engine, the intake air amount is measured,
Based on the measurement result, the fuel injection amount is controlled so that the air ratio becomes constant and a predetermined acceleration is obtained, and the ignition timing is also controlled. Various types of measuring devices for measuring the amount of intake air have been proposed in the past, and among them, a Karman vortex type air flow rate sensor (hereinafter referred to as Karman sensor) having excellent responsiveness is drawing attention. This Karman sensor utilizes the fact that when a vortex generator is placed on the intake side of an internal combustion engine, air vortices (Karman vortices) are generated in the vicinity of the vortex generator at a frequency proportional to the air flow rate. The pulse signal is generated at a timing related to the generation of the Karman vortex, and the period of the generated pulse signal is inversely proportional to the inflowing air amount at that time.

By the way, the air flow rate of the internal combustion engine fluctuates with a cycle of intake, exhaust, etc., and as shown in FIG. 1, the fluctuation range increases as the throttle valve opening increases. Since the Kalman sensor has a responsivity sufficient to follow such fluctuations, for example, as shown in FIG. 2, when the throttle valve opening is large and the flow rate is large, the cycle that occurs during the high flow rate period is shown. Of a very short pulse train and a pulse train of a relatively short cycle which occurs during the period of a small flow rate. Therefore, it becomes necessary to obtain the average of the pulse periods by some method.

As a general technique for this purpose, it is conceivable to divide the pulse signal every time corresponding to a predetermined angle of the engine crank angle and obtain the average thereof. This is to obtain an average for each period corresponding to one fluctuation cycle p of the instantaneous air flow rate, and the timing of the start point and end point of the period is given by the output of a predetermined angle of the crank angle sensor. With this method,
If the cycle p is set such that its start point and end point are in the middle of a large cycle as indicated by the symbol p ₁ in FIG. 2, these large cycles tl cannot be measured and the averaging error becomes too large. . Therefore, as shown by the symbol p ₂ in FIG. 2, the period p is set so as to include a large period tl, but even then the period of the pulse at the beginning and the end of the period p cannot be measured and an error remains, Normally, there is some delay time from the detection of the start point of the period p to the state where the pulse can be counted, so setting the start point at an extremely short position of the pulse period causes a counting error of the pulse number. There is an inconvenience due to the introduction of the error. Also,
Even if the amount of inflowing air is small, it can be averaged only for each predetermined engine speed, so that it has a drawback of poor responsiveness. Therefore, when the fuel injection control and the ignition timing control are performed based on the average air flow rate thus obtained, the responsiveness deteriorates when the engine speed is low, and the control is performed when the throttle valve opening is large and the flow rate is large. However, there was a problem in that high fuel injection and ignition timing control could not be performed.

OBJECT OF THE INVENTION The present invention is an improvement over these conventional drawbacks,
The purpose is to improve the accuracy of fuel injection control at the time of a large flow rate in which the instantaneous air flow rate fluctuates greatly, and to improve the response at the time of a small flow rate.

Principle, Structure, and Action of the Invention Generally, in a Kalman sensor, when the fluctuation range at a large flow rate is large, as shown in FIG. 2, a plurality of pulses appear and the state in which the pulse interval (cycle) is large is instantaneous air. The fluctuation of the flow rate appeared every cycle. Therefore, the predetermined value (Tma
x) If the average period is obtained each time a larger period appears, the average can be calculated for each period of fluctuation when the flow rate is large and the flow rate is large. Also, for convenience, the intervals (cycles) of the output pulses of the Kalman sensor at a small flow rate are sparse and generally large. Therefore, if the above is performed, the average is calculated for each pulse of the Kalman sensor at the time of the small flow rate, and the average period of the output pulse of the Kalman sensor can be obtained with good responsiveness at both the low flow rate and the high flow rate. Is possible. However, when the flow rate is medium, most of the pulse periods are smaller than an appropriate predetermined value (Tmax). For this reason, averaging at a medium flow rate becomes difficult only by obtaining the average period each time a period larger than the predetermined value (Tmax) appears.

Therefore, in the present invention, the average is calculated every time a predetermined number (Nmax) of pulses appear, and if a period larger than the predetermined value (Tmax) is detected, the average is calculated before the number becomes N. ing. By doing so, it is possible to obtain the average period of the output pulse of the Kalman sensor with good responsiveness both at low flow rate and high flow rate, and at average flow rate, at least every N pulses can be obtained even if the period of Tmax or more does not appear. Will be done.

Further, although it can be said that the average air flow rate at the time of a large flow rate is obtained with relatively high accuracy as described above, in practice, for example,
As shown, a large period t ₁ is followed by a relatively long period t ₂
Appears from time to time, and when this becomes a predetermined value (Tmax) or more, averaging is performed as indicated by symbol Q in the figure, and there is a case in which averaging is not performed accurately for each variation cycle of the instantaneous air flow rate. Therefore, in the present invention, the average air amount obtained as described above is further passed through a filter having a large time constant at the time of a large flow rate, so that appropriate control can be performed.

FIG. 4 is a diagram for explaining the configuration of the present invention, and the Kalman sensor CS
Pulse signal generated at a timing related to the generation of Karman vortices from the average period or average air flow rate calculating means AT.
Entered in. This calculation means AT is a pulse number counting means CN
The average period or the average air flow rate is calculated every time when a predetermined number (Nmax) of pulses are counted or when the pulse period detecting means PD detects a period of a predetermined time (Tmax) or more.
The filter means FT further smoothes the average period or the average air flow rate calculated by the calculating means AT, and the fuel injection amount calculating means IJ
The fuel injection amount calculation means IJ calculates a period during which fuel should be injected from the smoothed average period or average air flow rate and engine speed. The time constant changing means JV determines whether the flow rate is a small flow rate or a large flow rate based on the average period or the average air flow rate output from the calculating means AT, and if the flow rate is a large flow rate, increases the time constant of the filter means FT. , When the flow rate is small, reduce it.

When the ignition timing control is performed at the same time, the output of the filter means FT is divided into two systems, one for the fuel injection amount calculation means IJ and one for the ignition timing calculation means (not shown), and is input to the ignition timing calculation means. Output time constant is fuel injection amount calculation means
It should be larger than the time constant of the filter output input to IJ. This is because the ignition timing control requires higher accuracy and prevents the ignition timing calculated based on the average air amount having a large error from entering the knocking range.

FIG. 5 is a block diagram showing this processing. The output pulse of the Kalman sensor 30 is averaged by the averaging means 3 consisting of the calculating means AT, the pulse number counting means CN and the pulse period detecting means PD of FIG.
The average pulse period or the average air flow rate is calculated by inputting to 1 and the output of the averaging means 31 is input to the first and second filters 32 and 34 and the time constant changing means 33 and 35. The time constant changing means 33 and 35 determine the inflowing air amount from the average pulse period or the average air flow rate, and when the flow rate is small, the time constants m of the first and second filters,
The value of n is reduced and increased as the flow rate increases. Also, n
Change it to be> m. The output of the first filter 32 is input to the fuel injection amount calculation means 36, where the fuel injection time is calculated from the output of the engine speed detection means 37, and the injector is controlled via the control circuit 39. The output of the second filter 34 is input to the ignition timing calculation means 38, where the ignition timing is calculated from the engine speed and the igniter is controlled via the control circuit 40.

In FIG. 6, the output of the first filter 32 is input to the filter 50 having a fixed time constant, and the output of the filter 50 is input to the ignition timing calculation means 38. The time constant of the filter 50 may be changed similarly to the first filter 32.

FIG. 7 is a diagram for explaining the operation of the present invention, in which (a) shows an example of a temporal change in the instantaneous air flow rate, and (b) shows an example of the output pulse of the Kalman sensor at that time and averaged by the calculating means AT. The air flow rates Q1 to Q14 are shown. Also, Q in (c)
1'-Q14 'are the outputs of the filter means FT input to the fuel injection amount calculation means IJ, and (d) Q1 "-Q14" are the filter means input to the ignition timing calculation means for performing the ignition timing control. The output of FT is shown respectively. According to the configuration shown in FIG. 4, by setting the predetermined time (Tmax) to be slightly smaller than the maximum cycle that appears at the time of large flow rate, the average is calculated for each cycle of fluctuation at the time of high flow rate (see Q9 to Q11). ), The cycle of the output pulse of the Kalman sensor CS becomes a predetermined time (Tmax) or more when the flow rate is low, and the averaging is performed for each output pulse of the Kalman sensor CS (Q1 to Q6, Q12 to Q14).
reference). When the flow rate is medium, the average is calculated every time the pulse number counting means CN counts a predetermined number of pulses (Nmax) (Q7, Q
See 8). Further, for Q1 to Q6, Q13, Q14, for example, a filter having a time constant of 1 is applied, for Q7, Q8, Q12, a filter having a time constant of 2 is applied, and for Q9 to Q11, a filter having a time constant of 3, for example, is applied. It is output to the fuel injection amount calculation means IJ. An output filtered by a larger time constant is input to the ignition timing calculation means. In the example of FIG. 7, for Q1 to Q6, Q13, and Q14, for example, a filter having a time constant of 2 is input to Q7, Q8, and Q12. Is output to the fuel injection amount calculating means IJ after being filtered by a filter having a time constant of 3, and Q9 to Q11 are filtered at a filter having a time constant of 4, for example.

In addition, in FIG. 7, when shifting from a small flow rate to a medium flow rate,
The air flow rate for each pulse detection is suddenly switched to a large N average. This is because the predetermined number (Nmax) is fixed, and it cannot be denied that the responsiveness is somewhat impaired in this part. To improve this, the predetermined number (Nmax) may be sequentially increased within a predetermined range in relation to the count value of the pulse number counting means CN when the average is calculated. FIG. 8 is a diagram for explaining the operation of the present invention when such a measure is taken. The difference from FIG.
The average (Q7) of 3 pulses from t8 to pulse t10 is calculated, then the average (Q8) of 5 pulses from pulse t11 to pulse t15 is calculated, and then the 7 pulses from pulse t16 to pulse t22. The average (Q9) of the pulse is required. In this example, the predetermined number (Nmax) is sequentially increased by 2, but the rate of increase may be arbitrary. In FIG. 8, Q1 'to Q15' indicate the average air flow rate for fuel injection control, and Q1 "to Q15" indicate the average air flow rate for ignition timing control.

Further, the fluctuation period of the air flow rate is determined by the engine speed, and accordingly, the state of a large pulse interval (cycle) that appears at a large flow rate with a large fluctuation range of the instantaneous air flow rate also necessarily differs. Therefore, it is desirable to set the predetermined period (Tmax) in the pulse period detecting means PD to an optimum value according to the engine speed at that time. That is, the higher the engine speed, the smaller the predetermined cycle (Tmax).

Embodiment of the Invention FIG. 9 is a block diagram of an essential part of an embodiment of the present invention, in which 1 is an internal combustion engine, 2 is an air cleaner, 3 is a Kalman sensor, and its output signal a is " 1 ". 4 is a throttle chamber, 5 is an intake manifold, 6 is an electromagnetic fuel injector, 7 is a throttle valve that controls the flow of intake air,
8 is a crank angle sensor, 9 is a microprocessor, 10 is a memory, 11 is an output of the crank angle sensor 8 and other engine parameters such as cooling water temperature, intake air temperature, throttle valve opening, and on / off information of various switches such as idle switches. A data input unit for inputting to the microprocessor 9, a data output unit 12 and an igniter 13.

The intake air is supplied from the air cleaner 2 through the Kalman sensor 3 and the throttle chamber 4 to each cylinder from each branch of the intake manifold 5, fuel is injected into the internal combustion engine 1 by the fuel injector 6, and ignition of the fuel is performed by the igniter 13 Done in. The intake air volume is
It changes according to the state of the internal combustion engine as shown in FIGS. 7 and 8, and the output signal a also changes according to the change. The output signal a of the Kalman sensor 3 is input to the interrupt terminal INT of the microprocessor 9 and interrupted when the output signal a rises, for example.

FIG. 10 is a flow chart showing an example of this interrupt processing, and S1 to S15 show respective steps.

When interrupted, the microprocessor 9 first stores the time at that time as the latest pulse time T1 (S1), and increments the pulse count number N by +1 (S2). next,
It is determined whether or not the pulse count number N is a predetermined number (Nmax) or more. If the pulse count number N is a predetermined number (Nmax) or more, the process proceeds to step S6, and if it is less than the predetermined number, one pulse before the latest pulse time T1 The interrupt time T3 is subtracted to find the current pulse period T2, and it is determined whether T2 is equal to or longer than a predetermined period (Tmax) (S5). If T2 is equal to or greater than the predetermined period (Tmax), the process proceeds to step 6, and if it is less than the predetermined period (Tmax), the value of the latest pulse time T1 is set as the interrupt time T3 one pulse before (S15), and the main routine is restored. To do.

In step S6, the time T5 at the end of the previous averaging is subtracted from the latest pulse time T1 to obtain an inter-pulse time T4 to be averaged, and the average pulse period T6 is calculated by dividing this T4 by the number of pulses N (S7 ). This T6 corresponds to the output of the calculating means AT in FIG.

Next, the average pulse period Tinj for fuel injection control is calculated by the following equation (S8).

Tinj = {(n-1) Tinj + T6} / n (1) where n is a time constant.

Further, the average pulse period Tigt for ignition timing control is calculated by the following formula (S9).

Tigt = {(m-1) Tigt + T6} / m (2) Here, m is a time constant. The above equations (1) and (2) constitute the filter means.

When such processing ends, the latest pulse time T1 is stored as time T5 at the end of averaging (S10), and the predetermined number (N
The value of (max) is changed to the value obtained by adding the constant number α to the current pulse number N (S11). α is set to about 2 to 4, for example.
Further, in order to limit the maximum value of Nmax, Nmax is compared with a predetermined value β, and if larger than β, a process of clamping to the value of β is performed (S12, S13). When the averaging process is performed, the pulse count number N is cleared to zero to prepare for the next process (S14).

In addition, as shown in the flowchart of FIG. 11, the microprocessor 9 uses n = f ₁ (1 / T6 ×
The time constant n of the fuel injection control filter is changed by a relational expression (engine speed) (a relational expression in which the n value increases as the air flow rate increases) (S20), and m = f ₂ (1 / T6 × Relational expression in engine speed (m increases as air flow rate increases)
The value is increased, and the time constant n of the ignition timing control filter is changed by a relational expression such that m is larger than n) (S21). Then, the energization time of the fuel injector 6 is calculated by a known formula of injection time = f ₃ (Tinj) (S22), and the advance amount is obtained by the known formula of advance amount = f ₄ (Tigt) ( S23). Fuel injection and ignition control of the igniter 13 are performed according to these.

The flowchart of FIG. 10 corresponds to the embodiment of FIG. 5, and in order to realize the embodiment of FIG. 6, the step engine 9 of FIG. 10 may be replaced by the following steps.

Tigt ← {(l-1) Tigt + Tinj} / l (3) where l is a time constant, which may be a fixed value or variable.

As described above, the present invention detects the average air flow rate flowing into the internal combustion engine based on the cycle of the pulse signal generated at the timing related to the generation of Karman vortex from the Karman vortex type air flow rate sensor, In a device for calculating a fuel injection amount based on this, a pulse number counting means for counting the number of the pulse signals to be generated, a pulse cycle detecting means for counting the cycle of the pulse signals to be generated, and the pulse cycle detecting means. And a means for detecting a cycle of a predetermined time (Tmax) or more of the output of the above, the pulse number counting means counts a predetermined number (Nmax) of pulses, or the pulse cycle detecting means determines a predetermined time (Tmax). ) The averaging means that calculates the average period or the average air flow rate each time the above period is detected is adopted. When the width is large, as shown in Fig. 2,
A state in which the pulse interval (cycle) is large appears in each cycle of fluctuations in the instantaneous air flow rate, while the output pulse interval (cycle) of the Kalman sensor at a small flow rate is generally large. Basically, the average is calculated every time a predetermined number (Nmax) appears, and if a period larger than the predetermined value (Tmax) is detected, the average is calculated before the number of N is reached. When the flow rate is low, the average is calculated for each cycle, and when the flow rate is low, the average is calculated for each pulse of the Kalman sensor. It becomes possible to ask. Further, the filter means for averaging the average period or the average air flow rate calculated by the averaging means, the time constant changing means for increasing the time constant for averaging the filter means as the air flow rate increases, and the filter means The accuracy of fuel injection control at large flow rate when the instantaneous air flow rate fluctuates sharply because the fuel injection amount calculation means for calculating the fuel injection amount based on the output is provided and the detection error of the averaging means at the time of large flow rate is compensated. It is also possible to improve the responsiveness and improve the responsiveness at a small flow rate.

Furthermore, considering the total balance of fuel injection control and ignition timing control, the average air flow rate for ignition timing control is set to have a higher smoothness than the average air flow rate for fuel injection control, so the accuracy of ignition timing control is improved. However, it becomes possible to control the ignition timing near the knocking limit.

[Brief description of drawings]

FIG. 1 is a diagram showing the relationship between the throttle valve opening and the fluctuation of the instantaneous air flow rate flowing into the internal combustion engine, and FIG. 2 shows the instantaneous air flow rate at a large flow rate and the output pulse state of the Kalman sensor at that time. The diagram, FIG. 3 is a diagram showing the state of the output pulse of the Kalman sensor at the time of a large flow rate, FIG. 4 is a structural explanatory diagram of the present invention, and FIGS. 5 and 6 are both fuel injection and ignition timing control. FIG. 7 and FIG. 8 are diagrams for explaining the operation of the present invention, FIG. 9 is a block diagram of the essential parts of the embodiment of the present invention, and FIG.
11 is a flowchart showing an example of the interrupt processing of FIG. 11, and FIG. 11 is a flowchart showing the main part of the main routine of the microprocessor 9. 1 is an internal combustion engine, 2 is an air cleaner, 3 is a Kalman sensor, 4 is a throttle chamber, 5 is an intake manifold, 6 is an electromagnetic fuel injector, 7 is a throttle valve for controlling the flow of intake air, and 8 is a crank. An angle sensor, 9 is a microprocessor, 10 is a memory, 11 is a data input section, 12 is a data output section, and 13 is an igniter.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Teruo Fukuda Inventor Teruo Fukuda 1-228 Goshodori, Hyogo-ku Kobe Hyogo Prefecture Fujitsu Ten Limited (72) Inventor Akira Mori 1-chome Goshodori, Hyogo-ku, Hyogo Prefecture No. 28 No. 28 in Fujitsu Ten Limited (56) Reference JP-A-55-116101 (JP, A) JP-A-58-167834 (JP, A)

Claims (2)

[Claims] 1. An average air flow rate flowing into an internal combustion engine is detected based on a cycle of a pulse signal generated from a Karman vortex type air flow rate sensor at a timing related to generation of a Karman vortex, and fuel injection is performed based on the detected value. In an electronic internal combustion engine controller for determining the amount, a pulse number counting means for counting the number of the pulse signals generated, a pulse cycle detecting means for counting the cycle of the pulse signals generated, and a pulse cycle detecting means Means for detecting a cycle of a predetermined time (Tmax) or more of the output, the predetermined number (Nmax) of pulses is counted by the pulse number counting means, or a predetermined time (Tmax) is detected by the pulse cycle detecting means. Averaging means for calculating the average cycle or average air flow rate each time the above cycle is detected, and further averaging the average cycle or average air flow rate calculated by the averaging means Filter means, a time constant changing means for increasing the time constant for averaging the filter means as the air flow rate increases, and a fuel injection amount calculation means for calculating the fuel injection amount based on the output of the filter means. An electronic internal combustion engine control device characterized by the above. 2. An average air flow rate flowing into an internal combustion engine is detected based on a cycle of a pulse signal generated from a Karman vortex type air flow rate sensor at a timing related to generation of a Karman vortex, and fuel injection is performed based on the detected value. An electronic internal combustion engine controller for determining an amount and an ignition timing, comprising pulse number counting means for counting the number of pulse signals generated, and pulse cycle detection means for counting the cycle of the pulse signals generated, The average number or the average air flow rate is calculated every time the pulse number counting means counts a predetermined number (Nmax) of pulses or the pulse period detecting means detects a period of a predetermined time (Tmax) or more. And an average period or average air flow for averaging the average period or average air flow rate calculated by the averaging unit for fuel injection amount calculation and ignition timing calculation. The filter means for outputting the amount and the time constant for averaging the filter means are set to be larger for the ignition timing calculation than for the fuel injection amount calculation, and the time constant is increased as the air flow rate increases. A time constant changing means, a fuel injection quantity calculating means for calculating a fuel injection quantity based on an average cycle for calculating the fuel injection quantity of the filter means or an average air flow rate, and an average cycle for calculating the ignition timing of the filter means or the average air An electronic internal combustion engine control device comprising: an ignition timing calculation means for calculating an ignition timing based on a flow rate.