JPH01216050A - Fuel injection system under electric control for internal combustion engine - Google Patents

Abstract

PURPOSE:To reduce rippling of detection values of intake air quantity and improve operability by simply averaging a plurality of intake air quantity detection values for a predetermined number of revolutions of an engine, and putting the value of the weighted mean of its newest value and the previous weighted mean for an intake air flow. CONSTITUTION:A simple average is computed C for a plurality of intake air quantity detection values detected by an intake air quantity detecting means B for a predetermined number of revolutions of an engine, the newest average value and the previous weighted means are computed D to obtain a weighted mean, and this weighted mean value is outputted as an intake air flow signal. Weighting the newest simple average for this weighted means is changeably set G based on a value corresponding to the intake air flow for unit revolution of the engine for the normal operation condition and the momentary operation condition determined by a normal/momentary determining means F respectively. Fuel injection quantity is set E based on the intake air flow and an engine revolution speed by an engine revolution speed detecting means A, and a fuel injection means H is controlled.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an electronically controlled fuel injection device for an internal combustion engine, and more particularly to a technique for smoothing pulsations in a detected intake air flow rate.

<Prior art> Conventionally, in an internal combustion engine equipped with an electronically controlled fuel injection device, the fuel injection amount is set as follows (1983).
-Refer to Publication No. 183440, etc.).

That is, the basic fuel injection amount Tp (=K
XQ/N; is a constant), and this Tp is set as an air-fuel ratio mainly based on various correction coefficients C0EF depending on the cooling water temperature and an air-fuel ratio detected by an oxygen sensor installed in the exhaust system. Feedback correction coefficient LAMBDA
A correction calculation is performed using the correction numerator 3 based on the battery voltage and the final fuel injection amount Ti.

For example, in a single point injection (hereinafter referred to as SPI) system, an injection signal (valve opening drive signal) having a pulse width corresponding to the fuel injection amount Ti is sent to the electromagnetic fuel injection valve every % rotation of the engine. output and supply fuel to the engine by injecting it on and off.

<Problems to be Solved by the Invention> Incidentally, since intake pulsation occurs particularly when the engine is operated under high load, it is smoothed by an air flow meter and used for setting the injection amount.

One such smoothing process is to perform a simple average calculation. This is done by integrating the detected values of the intake air flow rate sampled at predetermined minute intervals between the fuel injection amount setting timings, and dividing this integrated value by the number of samples. A simple average value is obtained and this simple average value is used for calculating the injection amount.

However, since the state of intake pulsation differs for each cylinder, even if the simple averaging process is performed as described above, the processing result will be affected by the variation in intake pulsation between cylinders, as shown in Figure 5. As a result, fluctuations in the intake air flow rate cannot be effectively suppressed, and as a result, fluctuations in the basic fuel injection amount Tp occur, and this basic fuel injection amount Tp
The controllability of the ignition timing according to the current conditions deteriorates, leading to the occurrence of knocking and surges.

In addition, there is a system that takes a weighted average of the latest detected value of intake air flow rate and the past detected value at each timing of injection amount calculation synchronized with engine rotation, but in this case, the intake air flow rate between weighted average processing Since fluctuations in air flow rate are ignored, it is difficult to approximate the processing result to the true intake air flow rate.In addition, in order to effectively suppress intake pulsation under steady-state operating conditions, weighting is applied to the latest value. If it is made smaller, followability will deteriorate under accelerated driving conditions, and conversely, if the weighting of the latest value is increased in order to ensure followability under accelerated driving conditions, intake pulsation under steady driving conditions cannot be effectively suppressed. There was a problem.

The present invention has been developed in view of the above-mentioned problems, and is capable of effectively suppressing intake pulsation without being affected by cylinder-to-cylinder variation while ensuring follow-up performance in accelerated driving conditions. The purpose is to be able to obtain approximate values.

Therefore, in the present invention, as shown in FIG. 1, an engine rotation speed detection means for detecting the engine rotation speed, an intake air flow rate detection means for detecting the intake air flow rate of the engine, a fuel injection amount setting means for setting a fuel injection amount based on an engine operating state including a detected engine rotational speed and an intake air flow rate; and a fuel injection amount setting means for injecting and supplying the amount of fuel set by the fuel injection amount setting means to the engine. In an electronically controlled fuel injection device for an internal combustion engine, the electronically controlled fuel injection device for an internal combustion engine includes a fuel injection means, an average value for calculating a simple average of a plurality of intake air flow rate detection values detected by the intake air flow rate detection means while the engine rotates for a predetermined period. and a calculating means, each time the engine rotates at the predetermined speed, calculates a weighted average of the latest value of the simple average value calculated by the average value calculating means and the previous weighted average value, and uses the weighted average value as an intake air flow rate signal. weighted average calculating means for outputting to the fuel injection amount setting means; and steady/average calculating means for discriminating between a steady operating state and a transient operating state of the engine.
Transient discrimination means, and weighting of the latest simple average value in the weighted average by the weighted average calculation means for each of the steady operating state and transient operating state discriminated by the steady/transient discrimination means, respectively, per engine unit rotation. A weighting setting means for variable setting according to a value corresponding to the air flow rate is provided.

In this configuration, the fuel injection amount setting means sets the fuel injection amount based on the engine operating state including the engine rotation speed and intake air flow rate detected by the engine rotation speed detection means and the intake air flow rate detection means. .

The fuel injection means injects and supplies the amount of fuel set by the fuel injection amount setting means to the engine.

On the other hand, the average value calculation means calculates a simple average of a plurality of intake air flow rate detection values detected by the intake air flow rate detection means while the engine rotates at a predetermined time, and the weighted average calculation means calculates a simple average of the plurality of intake air flow rate detection values detected by the intake air flow rate detection means while the engine rotates at a predetermined time. A weighted average calculation is performed on the latest value and the previous weighted average value, and this weighted average value is outputted to the fuel injection amount setting means as an intake air flow rate signal. Further, the weighting setting means individually sets the weighting of the latest simple average value in the weighted average by the weighted average calculation means for the steady operating state and the transient operating state determined by the steady/transient determining means, respectively. It is set variably according to the value corresponding to the intake air flow rate.

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

In FIG. 2 showing the configuration of one embodiment, an intake manifold 2 of an engine 1 includes a throttle valve 3 disposed upstream from a branch portion to control the intake air flow rate in conjunction with an accelerator pedal.
An air flow meter 4 as an intake air flow rate detection means for detecting the intake air flow rate Q and a fuel injection valve 5 as a fuel injection means are provided on the upstream side thereof.The fuel injection valve 5 is controlled by a control unit 6 containing a microcomputer. The valve is opened by the injection pulse signal shown in the figure.
Fuel that is pressure-fed from a fuel pump and adjusted to a predetermined pressure is injected and supplied into the intake manifold 2.

Further, a water temperature sensor 7 for detecting the temperature of the cooling water in the cooling jacket of the engine 1 is provided, and an oxygen sensor 9 for detecting the oxygen concentration in the exhaust gas in the exhaust passage B is also provided. In addition, the distributor (not shown) has a built-in crank angle sensor 10 that also serves as an engine rotation speed detection means, and counts the crank angle unit signal output from the crank angle sensor IO in synchronization with the engine rotation for a certain period of time. Alternatively, the engine rotation speed N is detected by measuring the period of the crank reference angle signal.

Further, the shaft of the throttle valve 3 has a throttle valve opening T.
A throttle sensor 11 is provided to detect VO, and it is turned on when the throttle valve 3 is in the fully closed position (idle position).
An idle switch 12 is provided, and a neutral switch 13 is further provided that is turned on when the transmission is in a neutral state. The throttle sensor 11 and the control unit 6 constitute steady/transient discrimination means.

Next, the details of the basic fuel injection amount setting control including the smoothing process of the intake air flow rate detection value will be explained according to the routine shown in the flowcharts of FIGS. 3 and 4. In this embodiment, the functions of the fuel injection amount setting means, the average value calculation means, and the weighting setting means of the weighted average calculation means 9 are configured by software as shown in the above flowchart.

The basic fuel injection amount setting routine shown in the flowchart of FIG. 3 is executed every A rotation of the engine 1 based on a signal from the crank angle sensor 10.

In step 1 (indicated as "S" in the figure, the same applies hereinafter), the integrated value Q3□ of the intake air flow rate QA detected by the air flow meter 4 while the engine l rotates by % is divided by the number of samples ■ By doing this, the simple average value Qs+ of the intake air flow rate QA while the engine l rotates by %
Calculate Hpt (←Qsux/l).

The integrated value Q, L1. and the number of samples I are set in the integrated value setting routine shown in the flowchart of FIG.

Note that this routine is executed every 1 ms.

Here, in step 31, the output voltage Us of the air flow meter 4 is AD converted, and in the next step 32, data on the intake air flow rate QA, which is stored in a map in advance in correspondence with the output voltage Us, is selected. The data on the intake air flow rate QA corresponding to the output voltage Us obtained by AD conversion is searched and obtained.

Then, in step 33, the intake air flow rate QA obtained by searching in step 32 is added to the previous integrated value Qsun, and in the next step 34, each time the detected value QA of the air flow meter 4 is integrated in step 33, The value of the counter I is incremented by 1 to count the number of samples of the integrated value Q3-.

The integrated value Qsax obtained in this way and the number of samples ■
is used in step 1 to calculate the simple average value Qs+xrt of the intake air flow rate QA (detected value of the air flow meter 4) during each rotation of the engine 1.

In the next step 2, the integrated value Qso+4 and the number of samples I are reset to zero in order to newly set the integrated value Q3- and the number of samples ■ in the routine shown in the flowchart of FIG.

In step 3, in order to set the weighting in the weighted average processing described later, the intake air flow rate QA currently detected by the air flow meter 4 is divided by the engine rotation speed N (QA/N) to obtain a value representing the engine load. demand. Here, the simple average value Qs+wpt of the intake air flow rate QA during each rotation of the engine 1 calculated in step 1 may be divided by the engine rotation speed N, and the basic fuel injection amount T
The current engine rotational speed N and intake air flow rate QA or simple average value Q are added to the calculation formula for p (TP=KXQ/N: is a constant).
By substituting s+MpL, this basic fuel injection amount Tp may be used for setting the weighting.

In step 4, it is determined whether the current engine operating state is an idling operating state. Specifically, the idle switch 12 is ON and the neutral switch 13 is ON.
When this happens, it is determined that the engine is in an idling operating state.

If it is determined in step 4 that the engine is not in an idling state, the process proceeds to step 5 and the throttle sensor 11
Rate of change ΔTVO of throttle valve opening TVO detected at
Determine whether or not engine 1 is in deceleration operation based on 0. Whether or not engine 1 is in deceleration operation is determined when the rate of change ΔTVO is, for example, -166°/30IIIs or less. This is done so that it is determined that

Here, if it is determined that the engine 1 is in a deceleration operating state, the process proceeds to step 6 and the current operating state is shown in the Q graph).
Determine whether or not the engine is in the 61 region (operating region where the intake air flow rate QA does not change even if the throttle valve opening TVO changes) based on, for example, the current throttle valve opening TVO and the engine rotation speed N. However, if it is not included in the Q flat region, the process proceeds to step 11. On the other hand, if it is determined that it is included in the Q flat area, the process proceeds to step 7 in the same way as when it was determined in step 5 that the engine 1 is not in the deceleration operating state. .

In step 7, similarly to step 5, it is determined whether the engine 1 is in an accelerating operating state based on the throttle valve opening change rate ΔTVO. Here, for example, the rate of change Δ
It is determined that the accelerating driving state is occurring when the TVO is 1.6°/b.

If it is determined in step 7 that the engine 1 is in an accelerating operating state, the process proceeds to step 8, where the intake air flow rate QA is
The weighting constant X*iv (when this weighting constant Search and obtain based on the QA/N calculated in .

That is, as shown in the graph in the flowchart of FIG. 3, the current QA/N (value calculated in step 3) is calculated from among the weighting constant XILEV data stored in the map in advance according to the QA/N. Weighting constant X *tv corresponding to
is searched for, and the institution with the highest QA/N is 1.
During high-load operation, X1ltv is set to be large, so that the past weighted average value QAv□9 is given greater weight.

On the other hand, if it is determined in step 7 that the engine 1 is not in an accelerating operation state, the process proceeds to step 9, and similarly to step 8, the weighting constant X1tv is searched and determined based on QA/N.

However, the weighting constant In addition to effectively deterring
This is to ensure responsiveness in accelerated driving conditions. In this way, in this embodiment, the weighting constant XIEV is searched from each individual map based on the QA/N at that time depending on whether the engine is in an accelerating operation state or not.

Then, in step 8 or step 9, the weighting constant
When □9 is set, in the next step 10, the simple average value Qs+ of the intake empty current amount QA calculated in step 1 is calculated.
lpt and the weighted average value Qa calculated in the previous step 10
A weighted average calculation is performed using vmtv according to the following formula.

On the other hand, when it is determined in step 4 that the engine 1 is in the idle operating state, and in step 6 it is determined that the engine 1 is not in the SN range (in the deceleration operating state and not in the Q flat region), the process proceeds to step 11. Weighting constant
In addition to setting IIEV to zero, set the simple average value Qsr, L calculated in step 1 this time to the current weighted average value Q.
AVII! V, and the weighted average calculation in step 10 is not performed.

As described above, in this embodiment, a value close to the true intake air flow rate is obtained by simply averaging the detected values QA of the intake air flow rate sampled at minute intervals while the engine 1 rotates twice. In addition, by taking a weighted average of this simple average value Q31MPL, it is possible to absorb variations in intake pulsation between cylinders, thereby reducing fluctuations in the basic fuel injection amount Tp and adjusting the ignition timing based on the Tp. Improved controllability. In addition, weighted averaging is performed using weighted QA□l that differs depending on whether or not it is in an accelerated driving state, so it is possible to effectively control intake pulsation in a steady driving state while ensuring followability in an accelerated driving state. It can be suppressed.

When the calculation and setting of the weighted average value Qav■v is completed as described above, in the next step 12, whether or not the engine 1 is in a rapid acceleration operation state is determined by the throttle valve opening change rate Δ.
Judgment is made based on TVO. Here, for example, when the throttle valve opening change rate ΔTVO is 1.66/30<3> or more, it is determined that the engine I is in a rapid acceleration operation state, and when the sudden acceleration determination is made, the process proceeds to step 13.

In step 13, it is determined whether or not the sudden acceleration determination in step 12 is the first time, and when it is determined that it is the first time, the process proceeds to step 14 and the flag is set to 1, but if it is not the first time, step 14 is executed. Jump to step 15
Proceed to.

In step 15, a correction amount Δ is used to correct the detection delay of the air flow meter 4 in the rapid acceleration operation state of the engine l.
Q is calculated according to the following formula.

ΔQ= (Qav sect wv - previous Qav syllabus iv) KN
ANI, that is, the weighted average value Q calculated or set this time
A correction amount ΔQ is obtained by subtracting the previous weighted average value Qav+*tv from Av□ and multiplying the coefficient by □□.

The coefficients KNA and 4I are determined depending on the collector volume of the intake manifold 2 and the responsiveness of the air flow meter 4, and are set to a value of about 2.6, for example.

In the next step 16, it is determined whether the correction amount ΔQ calculated in step 15 is a value exceeding zero, and the correction amount ΔQ is determined.
When Q>0, the process proceeds to step 17 to determine the flag, and only when the correction amount ΔQ>O and the flag is 1, the process proceeds to step 18 to perform an increase correction on the intake air flow rate Q. Sten.

If it is determined in step 16 that the correction amount ΔQ≦O, the flag is set to zero in step 19, and then the process proceeds to step 20.

In step 18, the final intake air flow rate Q (final Q) is set by adding the correction amount ΔQ to the weighted average value Qav*tv calculated in step 10 this time to increase the amount. The weighted average value Qavltv calculated in step 10 is set as the final Q, and no increase correction is performed.

That is, in this embodiment, since the air flow meter 4 and the fuel injection valve 5 are provided upstream of the branch part of the intake manifold 2, the volume of the intake passage downstream of the fuel injection valve 5 is filled during sudden acceleration. However, since there is a delay in detecting the intake air flow rate Q which cannot be used for setting the fuel injection amount of the air flow meter 4, the correction amount ΔQ calculated in step 15 is used. However, even when the intake air flow rate Q has stabilized after rapid acceleration, if the increase correction is performed using the correction amount ΔQ, it will result in promoting intake pulsation, so this is not done in this embodiment. In order to solve this problem, once the weighted average value Qavwiv shows a decreasing tendency, the increase correction is not performed until there is a new sudden acceleration.

When the engine 1 is suddenly accelerated and the first determination is made in step 13, the flag is set to 1, and the flag is set to 1 until the weighted average value Qavwttv shows a decreasing tendency (until it is determined that the correction amount ΔQ≦0 in step 16). , an increase correction is performed in step 18, but when the weighted average value Qa and the engine pressure v start to show a decreasing tendency, the flag is set to zero in step 19, so the engine adjustment is performed based on the throttle valve opening change rate ΔTVO. Even if the sudden acceleration state of l is determined,
Since the final Q is set in step 20, the increase correction is not performed, and this prohibition state of increase correction continues until the initial determination of the sudden acceleration driving state is made again and the flag is set to 1.

Note that when the final Q is set in step 18 or step 20, the final Q is used in the next step 21 to calculate the basic fuel injection amount Tp (← × final Q/N; is a constant)
is calculated. Although omitted in this embodiment, in a separate routine, a correction numerator s based on the battery voltage, an air-fuel ratio detected by the oxygen sensor 9 (an air-fuel ratio feedback correction coefficient LAMBDA, and a cooling water detected by the water temperature sensor 7 Various correction coefficients C0 based on temperature etc.
The basic fuel injection amount Tp is corrected by EF or the like to set the final fuel injection amount Ti, and an injection pulse signal corresponding to this fuel injection amount Ti is output to the fuel injection valve 5 in synchronization with the engine rotation. Then, fuel is injected and supplied to the engine 1 on and off.

<Effects of the Invention> As explained above, according to the present invention, the pulsations in the detected value can be smoothed to a value close to the true intake air flow rate without being affected by variations in intake pulsation between cylinders. It is possible to reduce fluctuations in the basic fuel injection amount due to intake pulsation, and by changing the weighting between steady and transient operating conditions, it ensures followability during acceleration operating conditions and effectively reduces intake pulsation during steady operating conditions. There is an effect that it can be done.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing the configuration of the present invention, Fig. 2 is a system diagram showing an embodiment of the invention, Figs. 3 and 4 are flowcharts showing the control contents of the above embodiment, and Fig. 5 is a It is a time chart for explaining the conventional problems. 1... Engine 2... Intake manifold 3...
Throttle valve 4... Air flow meter 5...
・Fuel injection valve 6...Control unit 1
0... Crank angle sensor 11... Throttle sensor Patent applicant Japan Electronics Co., Ltd. Representative Patent attorney Fujio Sasashima Figure 2

Claims (1)

[Scope of Claims] An engine rotation speed detection means for detecting the engine rotation speed, an intake air flow rate detection means for detecting the intake air flow rate of the engine, and an engine operating state including the detected engine rotation speed and intake air flow rate. An electronically controlled fuel injection device for an internal combustion engine, comprising: a fuel injection amount setting means for setting a fuel injection amount based on the fuel injection amount setting means; and a fuel injection means for injecting and supplying the amount of fuel set by the fuel injection amount setting means to the engine. an average value calculation means for calculating a simple average of a plurality of intake air flow rate detection values detected by the intake air flow rate detection means while the engine rotates at a predetermined time; weighted average calculation means for calculating a weighted average of the latest value of the simple average calculated by the means and the previous weighted average value, and outputting the weighted average value to the fuel injection amount setting means as an intake air flow rate signal; Steady/
Transient discrimination means, and weighting of the latest simple average value in the weighted average by the weighted average calculation means for each of the steady operating state and transient operating state discriminated by the steady/transient discrimination means, respectively, per engine unit rotation. An electronically controlled fuel injection device for an internal combustion engine, comprising: weighting setting means for variably setting weights according to a value corresponding to an air flow rate.