JPH0768927B2 - Electronically controlled fuel injection device for internal combustion engine - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronically controlled fuel injection device for an internal combustion engine, and more particularly to a technique for smoothing a pulsation of 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 (actual development 61-
See 183440, etc.).

That is, from the intake air flow rate Q detected by the air flow meter and the engine rotation speed N, the basic fuel injection amount Tp (= K × Q /
N; K is a constant), and this Tp is set based on various correction factors COEF mainly according to the cooling water temperature and the air-fuel ratio detected by the oxygen sensor installed in the exhaust system. The final fuel injection amount Ti is determined by performing a correction calculation using the coefficient LAMBDA and the correction amount Ts based on the battery voltage.

Then, 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 given to the electromagnetic fuel injection valve every 1/2 revolution of the engine. Is output, and fuel is injected and supplied to the engine on / off.

<Problems to be solved by the invention> By the way, since intake pulsation occurs particularly during engine high load operation, the intake air flow rate detected by the air flow meter is not used as it is for setting the basic fuel injection amount Tp, but The detected value is smoothed and used for setting the injection amount.

As one of such smoothing processing, there is one that performs a simple average calculation. This is a simple average of the detection values between the fuel injection timings by integrating the detection values of the intake air flow rate sampled at every predetermined minute time between the fuel injection amount setting timings and dividing the integrated value by the number of samples. The value is obtained and this simple average value is used for the injection amount calculation.

However, since the state of the intake pulsation differs for each cylinder, even if the simple averaging process is performed as described above, the processing result is affected by the variation in the intake pulsation among the cylinders as shown in FIG. Therefore, the fluctuation of the intake air flow rate cannot be effectively suppressed, resulting in the fluctuation of the basic fuel injection amount Tp, and the controllability of the ignition timing according to the basic fuel injection amount Tp. However, there is a fear of causing knocking and surge.

In addition, there is a method in which the latest detected value and the past detected value of the intake air flow rate are weighted averaged at each injection amount calculation timing synchronized with the engine rotation. Since the fluctuation of the air flow rate is ignored, it is difficult to approximate the processing result to the true intake air flow rate, and the latest value is weighted in order to effectively suppress the intake pulsation in the steady operation state. If the value is made small, the followability deteriorates in the acceleration operation state, and conversely, if the weighting for the latest value is increased in order to ensure the followability in the acceleration operation state, this time it becomes impossible to effectively suppress the intake pulsation in the steady operation state. There was a problem.

The present invention has been made in view of the above problems, it is possible to effectively suppress the intake pulsation without being affected by the variation between the cylinders while ensuring the followability in the acceleration operation state, and to the true intake air flow rate. The purpose is to be able to obtain an approximate value.

<Means for Solving the Problem> Therefore, in the present invention, as shown in FIG. 1, an engine rotational speed detecting means for detecting an engine rotational speed, an intake air flow rate detecting means for detecting an intake air flow rate of the engine, Fuel injection amount setting means for setting the fuel injection amount based on the engine operating state including the detected engine speed and intake air flow rate, and the amount of fuel set by the fuel injection amount setting means is injected and supplied to the engine. In an electronically controlled fuel injection device for an internal combustion engine including 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 during a predetermined rotation of the engine. Each time the engine rotates a predetermined number of times, the calculating means calculates the 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 calculates the weighted average value by the intake air flow rate signal. Signal output to the fuel injection amount setting means as a signal, and a steady-state operation for distinguishing between a steady operation state and a transient operation state of the engine.
Intake of the latest simple average value in the weighted average by the weighted average calculation means for each of the transient determination means and the steady operating state and the transient operating state determined by the steady / transient determination Weighting setting means for variably setting according to the value corresponding to the air flow rate is provided.

<Operation> In such a configuration, the fuel injection amount setting means sets the fuel injection amount based on the engine operating state including the engine rotation speed and the intake air flow rate detected by the engine rotation speed detection means and the intake air flow rate detection means. . And the fuel injection means is
The amount of fuel set by the fuel injection amount setting means is injected and supplied to the engine.

On the other hand, the average value calculating means calculates a simple average of a plurality of intake air flow rate detection values detected by the intake air flow rate detecting means during a predetermined rotation of the engine, and the weighted average calculating means calculates the simple average value of the simple average values. The latest value and the previous weighted average value are weighted averaged, and this weighted average value is output to the previous fuel injection amount setting means as an intake air flow rate signal. Further, the weighting setting means individually weights the latest simple average value in the weighted average by the weighted average calculation means in the steady operation state and the transient operation state determined by the steady / transient determination means per engine unit revolution. It is variably set according to the value corresponding to the intake air flow rate.

<Examples> Examples of the present invention will be described below with reference to the drawings.

Referring to FIG. 2 showing the structure of one embodiment, an intake manifold 2 of an engine 1 has a throttle valve 3 upstream of a branch portion for controlling an intake air flow rate in cooperation with an accelerator pedal.
And an air flow meter 4 as an intake air flow rate detecting 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 of the control unit 6 including a microcomputer. The valve is driven to open by the injection pulse signal of, and fuel supplied under pressure from a fuel pump (not shown) 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 passage 8 is provided. Further, a distributor (not shown) has a built-in crank angle sensor 10 that also serves as engine speed detection means, and counts a crank angle unit signal output from the crank angle sensor 10 in synchronization with the engine rotation for a certain period of time. Alternatively, the engine rotation speed N is detected by measuring the cycle of the crank reference angle signal.

Further, the axis of the throttle valve 3 has a throttle valve opening TV
A throttle sensor 11 for detecting O is provided, and
An idle switch 12 that is turned on at the fully closed position (idle position) of the throttle valve 3 is provided, and a neutral switch 13 that is turned on when the transmission is in a neutral state is provided. The throttle sensor 11 constitutes a steady / transient determination means together with the control unit 6.

Next, the contents of the basic fuel injection amount setting control including the smoothing process of the intake air flow rate detection value will be described according to the routines shown in the flowcharts of FIGS. 3 and 4. In this embodiment, the functions of the fuel injection amount setting means, the average value calculating means, the weighted average calculating means, and the weight setting means are configured by software as shown in the above flow chart.

The basic fuel injection amount setting routine shown in the flowchart of FIG. 3 is executed every 1/2 rotation of the engine 1 based on the signal from the crank angle sensor 10.

In step (denoted as "S" in the figure, the same applies hereinafter) 1, the integrated value Q _SUM of the intake air flow rate QA detected by the air flow meter 4 while the engine 1 is rotating 1/2 is used as the sample number I. By dividing by
Simple average value of intake air flow rate QA during rotation Q _SIMPL
Calculate (← Q _SUM / I).

The integrated value Q _SUM and the sample number I are set by 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, the output voltage Us is previously converted.
Intake air flow rate QA stored in the map corresponding to Us
Output voltage obtained by AD conversion in step 31 from the data of
Search for and obtain the intake air flow rate QA data corresponding to Us.

Then, in step 33, the intake air flow rate QA obtained by searching in step 32 is added to the accumulated value Q _SUM so far, and in the next step 34, the detected value of the air flow meter 4 in step 33.
Every time QA is integrated, the value of the counter I is incremented by 1 and the number I of samples of the integrated value Q _SUM is counted.

The integrated value Q _SUM and the number of samples I thus obtained are used in the step 1 and the intake air flow rate QA (detection value of the air flow meter 4) during the 1/2 revolution of the engine 1
The simple average value of Q _SIMPL is calculated.

In the next step 2, the integrated value Q _SUM and the sample number I are reset to zero in order to newly set the integrated value Q _SUM and the sample number I in the routine shown in the flowchart of FIG.

In step 3, in order to set the weighting in the weighted averaging process described later, the intake air flow rate QA currently detected by the air flow meter 4 is divided by the engine speed N (QA / N) to obtain a value representing the engine load. Ask. In addition, here
The simple average value Q _SIMPL of the intake air flow rate QA during the half rotation of the engine 1 calculated in step 1 may be divided by the engine rotation speed N, and the calculation formula (Tp of the basic fuel injection amount Tp
= K × Q / N; K is a constant), the current engine speed N and the intake air flow rate QA or the simple average value Q _SIMPL are substituted, and the basic fuel injection amount Tp is used for setting the weighting. good.

In step 4, it is determined whether the current engine operating state is the idle operating state. Specifically, when the idle switch 12 is ON and the neutral switch 13 is ON, it is determined that the engine is in the idle operation state.

If it is determined in step 4 that the engine is not in the idle operation state, the process proceeds to step 5 to determine whether the engine 1 is in the deceleration operation state based on the change rate ΔTVO of the throttle valve opening TVO detected by the throttle sensor 11. To judge. Whether or not the engine 1 is in the decelerating operation state is determined to be in the decelerating operation state when the rate of change ΔTVO is, for example, −1.6 ° / 30 ms or less.

Here, when it is determined that the engine 1 is in the decelerating operation state, the routine proceeds to step 6, where the current operating state is the Q flat region (even if the throttle valve opening TVO changes, the intake air flow rate Q
Whether A is included in the unchanged operating region) is determined based on, for example, the current throttle valve opening TVO and the engine speed N, and when it is not included in the Q flat region, the process proceeds to step 11, , Q, it is determined that the engine 1 is not in the decelerating operation state in step 5, and the process proceeds to step 7.

In step 7, as in step 5, it is determined based on the throttle valve opening change rate ΔTVO whether the engine 1 is in the accelerating operation state. Here, for example, the change rate ΔTV
When O is 1.6 ° / 100ms or more, it should be judged that it is in the acceleration operation state.

Then, when it is determined in step 7 that the engine 1 is in the acceleration operation state, the process proceeds to step 8 and the weighting constant in the weighted average calculation formula when _{performing the} weighted average calculation of the simple average value Q _SIMPL of the intake air flow rate QA. X _REV (the past value is weighted more when this weighting constant X _REV is large) is searched for based on the QA / N calculated in step 3.

That is, as shown in the graph in the flowchart of FIG. 3, the current QA / N (calculated value in step 3) is selected from the data of the weighting constant X _REV stored in the map in advance according to the QA / N. ) Is obtained by searching for the weighting constant X _REV , and X _REV is set larger as the engine 1 with a higher QA / N _operates under higher load, and the weighting with respect to the past weighted average value Q _AVREV is It's getting bigger.

On the other hand, if it is determined in step 7 that the engine 1 is not in the acceleration operation state, the process proceeds to step 9 to search for the weighting constant X _REV based on QA / N as in step 8. However, the weighting constant X _REV searched in step 9 when the engine 1 is not in the accelerating operation state is larger than that in the accelerating operation state.
The QA / N is set to a larger value, which effectively suppresses intake pulsation and ensures responsiveness in the acceleration operation state. As described above, in the present embodiment, the weighting constant X _REV is retrieved from each individual map based on the QA / N at that time depending on whether the engine is in the accelerated operation state.

Then, in step 8 or step 9, the weighting constant X
_{When REV} is set, in the next step 10, using the simple average value Q _SIMPL of the intake air flow rate QA calculated in step 1 this time and the weighted average value Q _AVREV calculated in step 10 last time, the weight is calculated according to the following equation. Performs averaging.

On the other hand, when it is determined in step 4 that the engine 1 is in the idle operation state and when it is determined in step 6 that the engine 1 is not in the Q flat region (in the decelerating operation condition and not in the Q flat region), the process proceeds to step 11 and the weighting is performed. The constant X _REV is set to zero, the simple average value Q _SIMPL calculated in step 1 this time is set as the weighted average value Q _AVREV this time, and the weighted average calculation in step 10 is not performed.

As described above, in the present 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 every minute time while the engine 1 makes 1/2 rotation. This simple average with
The intake pulsation variation between the cylinders can be absorbed by performing the weighted average of Q _SIMPL , so that the basic fuel injection amount Tp
Of the ignition timing is improved and the controllability of the ignition timing based on the Tp is improved. In addition, since weighted averaging is _performed by using the weighted Q _AVREV that varies depending on whether the vehicle is in the accelerating operation state, the intake pulsation in the steady operating state is effectively suppressed while ensuring the followability in the accelerating operating state. It is possible.

When the calculation and setting of Q _AVREV are completed as described above, in the next step 12, whether or not the engine 1 is in the rapid acceleration operation state is determined based on the throttle valve opening change rate ΔTVO. Here, for example, the throttle valve opening change rate ΔTVO
Is 1.6 ° / 30 ms or more, it is determined that the engine 1 is in the rapid acceleration operation state, and when the rapid acceleration determination is made, the process proceeds to step 13.

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

In step 15, the correction amount ΔQ for correcting the detection delay of the air flow meter 4 in the rapid acceleration operation state of the engine 1
Is calculated according to the following formula.

ΔQ ← (Q _AVREV -Previous Q _AVREV ) K _MANI That is, the correction amount ΔQ is obtained by multiplying the coefficient K _MANI by the value _obtained by subtracting the previous weighted average value Q _AVREV from the weighted average value Q _AVREV calculated or set this time. To be The coefficient K _MANI
Is determined according to the collector volume of the intake manifold 2 and the responsiveness of the air flow meter 4, for example, 2.
The value should be around 6.

In the next step 16, the correction amount ΔQ calculated in step 15
Is determined to be a value exceeding zero, and the correction amount ΔQ>
When it is 0, the routine proceeds to step 17, where the flag is judged, and only when the correction amount ΔQ> 0 and the flag is 1, the routine proceeds to step 18 where the intake air flow rate Q is increased and corrected. On the other hand, when it is determined in step 16 that the correction amount ΔQ ≦ 0, 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 increasing the correction amount ΔQ by adding the correction amount ΔQ to the weighted average value Q _AVREV calculated in step 10 this time. Weighted average value Q calculated in 10
_AVREV 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 in the upstream portion of the branch portion of the intake manifold 2, the volume of the intake passage on the downstream side of the fuel injection valve 5 is filled at the time of sudden acceleration. However, the correction amount ΔQ calculated in step 15 is used because there is a detection delay of the intake air flow rate Q that cannot be used for setting the fuel injection amount of the air flow meter 4. It is necessary to correct the amount by increasing the intake air flow rate Q after the sudden acceleration.
Since the intake pulsation is promoted if the increase correction by the correction amount ΔQ is performed even when is stable, in the present embodiment, in order to solve this, once the weighted average value Q _AVREV shows a decreasing tendency, a new The increase correction is not performed until the vehicle is suddenly accelerated.

When the engine 1 is rapidly accelerated and the first determination is made in step 13, the flag is set to 1 and the weighted average value Q _AVREV shows a decreasing tendency (until it is determined in step 16 that the correction amount ΔQ ≦ 0). Is corrected in step 18, but when the weighted average value Q _AVREV shows a decreasing tendency, the flag is set to zero in step 19, so that the engine 1 Even if the rapid acceleration state is determined, the final Q is set in step 20 so that the increase correction is not performed, and until the rapid acceleration operation state is again determined for the first time and the flag is set to 1. This prohibition state of the increase correction continues.

When the final Q is set in step 18 or step 20, the basic fuel injection amount Tp (← K × final Q / N; K is a constant) is calculated using the final Q in the next step 21. Although omitted in the present embodiment, the correction amount Ts based on the battery voltage, the air-fuel ratio feedback correction coefficient LAMBDA based on the air-fuel ratio detected by the oxygen sensor 9 and the cooling water temperature detected by the water temperature sensor 7 in another routine, etc. The basic fuel injection amount Tp is corrected and calculated by various correction factors such as COEF based on the above, and the final fuel injection amount Ti is set, and the injection pulse signal corresponding to this fuel injection amount Ti is injected in synchronization with the engine rotation. The fuel is output to the valve 5 and the fuel is injected and supplied to the engine 1 on / off.

<Effect of the Invention> As described above, according to the present invention, the pulsation of the detected value can be smoothed at a value close to the true intake air flow rate without being affected by the intake pulsation variation between the cylinders. The fluctuation of the basic fuel injection amount due to intake pulsation can be reduced, and the weighting can be changed between steady and transient operating conditions to ensure followability in accelerated operating conditions and effectively reduce intake pulsation in steady operating conditions. The effect is that you can do it.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of the present invention, FIG. 2 is a system diagram showing an embodiment of the present invention, FIGS. 3 and 4 are flow charts showing control contents of the same embodiment, and FIG. It is a time chart for explaining the conventional problem. 1 ... Engine, 2 ... Intake manifold, 3 ... Throttle valve, 4 ... Air flow meter, 5 ... Fuel injection valve, 6 ...
Control unit, 10 Crank angle sensor, 11
...... Throttle sensor

Claims (1)

[Claims] 1. An engine speed detecting means for detecting an engine speed, an intake air flow rate detecting means for detecting an intake air flow rate of the engine, and an engine operating state including the detected engine speed and intake air flow rate. In an electronically controlled fuel injection device for an internal combustion engine, comprising: a fuel injection amount setting means for setting a fuel injection amount by a fuel injection means; and a fuel injection means for injecting an amount of fuel set by the fuel injection amount setting means to the engine. An average value calculating means for calculating a simple average of a plurality of intake air flow rate detection values detected by the intake air flow rate detecting means during a predetermined rotation of the engine; and an average value calculating means each time the engine performs the predetermined rotation. Weighted average calculation means for performing the weighted average calculation of the latest value of the simple average value and the previous weighted average value, and outputting the weighted average value as the intake air flow rate signal to the fuel injection amount setting means. , Steady-state to determine the transient operation state and the steady operating state of the engine,
Intake of the latest simple average value in the weighted average by the weighted average calculation means for each of the transient determination means and the steady operating state and the transient operating state determined by the steady / transient determination An electronically controlled fuel injection device for an internal combustion engine, comprising: a weight setting unit that variably sets a value corresponding to an air flow rate.