JP2688211B2 - Fuel injection amount control method for internal combustion engine - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a fuel injection amount control method for controlling the fuel injection amount of an internal combustion engine.

2. Description of the Related Art In a so-called electronically controlled fuel injection device for an internal combustion engine, a typical prior art is that the state quantity TPD obtained from the intake pipe pressure Pm and the rotation speed Ne of the internal combustion engine per unit time is typical.
Was used as the actual fuel injection amount TAU. Therefore, due to the influence of the capacity of the intake passage from the downstream side of the throttle valve including the surge tank to the intake pipe of each combustion chamber, the intake pipe is Since the pressure Pm changes slowly, the fuel injection amount
While TAU is stable, it may cause a delay in response.

In order to solve this problem, in the method previously proposed by the applicant of the present application, the state quantity TPQ obtained from the intake air flow rate Q and the rotational speed Ne is used to correct the state quantity TPD to perform actual fuel injection. The amount TAU is sought, and the responsiveness is improved.

However, in this method, the state quantities TPD and TPQ that should match in a steady state other than the transient time are errors during matching, that is, the map values of these state quantities TPD and TPQ, for example, exhaust gas. The air-fuel ratio is not stable because the error does not always occur when the rewriting is performed according to the learning depending on the oxygen concentration in the inside and the change in the charging efficiency.

Further, in the case of an internal combustion engine having an exhaust gas recirculation function (hereinafter abbreviated as EGR), the intake air flow rate Q is the sum of the fresh air intake flow rate Q1 and the exhaust gas recirculation amount Q2.
Even when the intake air flow rate Q is constant, the fresh air intake flow rate Q1 is different between when the EGR is ON and when it is OFF. Therefore, in the prior art, the fuel injection amount TAU is several percent when the EGR is ON, when it is OFF. In order to reduce the number of states, it was dealt with by switching the map for reading the state quantity TPQ. Therefore, if such a map switching operation is performed at the same time as the EGR ON / OFF operation, the air-fuel ratio will shift during a transition until the recirculation amount Q2 stabilizes.

An object of the present invention is to change the opening of the throttle valve and the O of the EGR.
Fuel injection amount control method for an internal combustion engine that has good responsiveness during transients such as N / OFF and good stability during steady state, and that can always maintain the air-fuel ratio at an optimum value. Is to provide.

Means for Solving the Problems The present invention relates to a first aspect related to an intake air flow rate passing through a throttle valve by obtaining a basic injection amount using an intake pipe pressure.
A second quantity related to the flow rate of intake air supplied to the internal combustion engine so as to obtain a state quantity and follow the first state quantity with a time delay.
The state quantity is obtained, and when the first state quantity is obtained, the opening amount of the throttle valve and the second state quantity are used, and the correction quantity is obtained based on the difference between the first state quantity and the second state quantity, A fuel injection amount control method for an internal combustion engine, characterized in that a fuel injection amount is obtained from the basic injection amount and the correction amount.

Further, the present invention is characterized in that the second state quantity is an injection quantity obtained by using a delayed expected intake pipe pressure, and the first state quantity is an injection quantity obtained by an expected intake pipe pressure. A fuel injection amount control method for an internal combustion engine.

Further, in the present invention, the second state quantity is a delayed predicted intake pipe pressure, the first state quantity is a predicted intake pipe pressure, and the correction amount is the predicted intake pipe pressure and the delayed predicted intake pipe pressure. A fuel injection amount control method for an internal combustion engine, which is characterized in that it is obtained from a difference with a pressure.

The present invention also uses the intake pipe pressure to determine the basic injection amount, and relates to the first air flow rate related to the intake air flow rate passing through the throttle valve.
The state quantity is obtained as an injection quantity based on the predicted intake pipe pressure, and the second state quantity related to the intake air flow rate supplied to the internal combustion engine is set as the injection quantity based on the delayed predicted intake pipe pressure. Is calculated so as to follow up with a time delay, a correction amount is calculated based on the difference between the first state amount and the second state amount, and a fuel injection amount is calculated from the basic injection amount and the correction amount. A fuel injection amount control method for an internal combustion engine, comprising:

The present invention also uses the intake pipe pressure to determine the basic injection amount, and relates to the first air flow rate related to the intake air flow rate passing through the throttle valve.
The state quantity is obtained as the predicted intake pipe pressure, and the second state quantity related to the intake air flow rate supplied to the internal combustion engine is changed as the delayed predicted intake pipe pressure so as to follow the first state quantity with a time delay. The fuel amount of the internal combustion engine, wherein a correction amount is obtained based on a difference between the predicted intake pipe pressure and the delayed predicted intake pipe pressure, and a fuel injection amount is obtained from the basic injection amount and the correction amount. This is an injection amount control method.

Further, in the present invention, the intake air flow rate passing through the throttle valve is obtained by using the opening degree of the throttle valve and the second state amount, and the fresh air intake flow rate passing through the throttle valve and the exhaust gas recirculation flow rate are calculated. A fuel injection amount control method for an internal combustion engine, which is a sum of intake total flow rates.

Furthermore, the present invention obtains the basic injection amount using the intake pipe pressure and determines the first injection amount related to the intake intake flow rate passing through the throttle valve.
The state quantity is obtained, and the second state quantity that is associated with the intake air flow rate supplied to the internal combustion engine is obtained by following and changing the first state quantity with a time delay, and the first state quantity and the second state quantity. And a second correction amount related to the second state amount and the capacity of the intake path including the surge tank, the basic injection amount and the first and second correction amounts. And a fuel injection amount control method for an internal combustion engine, wherein the fuel injection amount is obtained from the fuel injection amount.

Operation According to the present invention, the basic injection amount is obtained using the intake pipe pressure. Next, a first state quantity related to the intake air flow rate passing through the throttle valve is determined, and related to the intake air flow rate supplied to the internal combustion engine so as to follow the first state quantity with a time delay. The second state quantity is calculated,
When determining the first state quantity, the throttle valve opening and the second
State quantities are used. Subsequently, a correction amount is obtained based on the difference between the first state amount and the second state amount, and an actual fuel injection amount is obtained from the basic injection amount and the correction amount. Thus, the first state quantity used to obtain the correction amount is virtually obtained using the opening degree of the throttle valve and the second state quantity. Therefore, in the steady state, the first state quantity and the second state quantity are Since the state quantities are substantially the same, the correction quantity can be accurately obtained. Further, the opening degree of the slottling valve is used in obtaining the first state quantity, and the opening degree of this slottling valve has a good responsiveness. Therefore, the correction amount can be obtained with a good responsiveness.

Further, according to the present invention, the injection amount is used as the state amount. That is, the second state quantity is the injection quantity obtained using the delayed expected intake pipe pressure, and the first state quantity is the injection quantity obtained from the expected intake pipe pressure. By using these injection quantities, The correction amount can be accurately obtained.

Further, according to the present invention, the state quantity related to the intake pipe pressure is used as the state quantity. That is, the second state quantity is the delayed predictor pressure and the first state quantity is the predicted intake pipe pressure, and the correction amount can be accurately obtained from the difference between the predicted intake pipe pressure and the delayed predicted intake pipe pressure.

Further, according to the present invention, the basic injection amount is obtained using the intake pipe pressure. Next, a first state quantity related to the intake air flow rate passing through the throttle valve is obtained as an expected intake pipe pressure or an injection amount based on the predicted intake pipe pressure, and a first state quantity related to the intake air flow rate supplied to the internal combustion engine is obtained. The two-state quantity is calculated so as to follow the first state quantity with a time delay as an injection amount based on the predicted delayed intake pipe pressure or as an injection amount based on this. Subsequently, a correction amount is obtained based on the difference between the first state amount and the second state amount, and an actual fuel injection amount is obtained from the basic injection amount and the correction amount. In this way, the first state quantity and the second state quantity used to obtain the correction amount are the predicted intake pipe pressure, or the injection amount based on this, and the delayed predicted intake pipe pressure or the injection based on this, respectively. Since it is virtually determined by the amount, in the steady state, the first state amount and the second state amount substantially match, and the correction amount can be accurately obtained. Further, when obtaining the correction amount, the predicted intake pipe pressure or the injection amount based on it is used as the first state amount, and the delayed predicted intake pipe pressure or the injection amount based on this is used as the second state amount. The intake pipe pressure or the injection amount based on the intake pipe pressure has a good responsiveness, and therefore, the fuel injection amount can be obtained with a high responsiveness.

Further, according to the invention, the intake air flow rate passing through the throttle valve is obtained by using the opening degree of the throttle valve and the second state amount, and is the sum of the fresh air intake flow rate passing through the throttle valve and the exhaust gas recirculation flow rate. Since it is the total intake air flow rate, fluctuations in the air-fuel ratio can be suppressed even during the transient (ON) / end (OFF) transition of exhaust gas recirculation.

Further according to the present invention, the basic injection amount is obtained using the intake pipe pressure. Next, a first state quantity related to the intake air flow rate passing through the throttle valve is obtained, and the first state quantity follows and changes with a time delay to obtain a first state quantity related to the intake air flow rate supplied to the internal combustion engine. Two state quantities are required.
Then, the first state quantity is calculated based on the difference between the first state quantity and the second state quantity.
The correction amount is obtained, the second correction amount related to the second state amount and the capacity of the intake path is obtained, and the actual fuel injection amount is obtained from the basic injection amount and the first and second correction amounts. . As described above, in addition to the first correction amount, the second delay considering the intake delay due to the intake path, the atmospheric pressure correction at high altitude, etc.
Since the correction is performed by the correction amount, the actual fuel injection amount can be controlled with higher accuracy.

Embodiment FIG. 1 is a block diagram of one embodiment of the present invention. A plurality of combustion chambers E1 to Em are formed in the internal combustion engine 13, and combustion air is supplied from the intake pipe 15 to these combustion chambers E1 to Em. A throttle valve 16 is interposed in the intake pipe 15. The combustion air passing through the throttle valve 16 is guided from the surge tank 14 to the intake pipes A1 to Am provided individually for each of the combustion chambers E1 to Em. Each of the intake pipes A1 to Am has a fuel injection valve B1
To Bm are provided, and in each explosion stroke in each of the combustion chambers E1 to Em, injection is performed with a fuel injection amount TAU determined by a processing device 31 described later. The combustion chambers E1 to Em are provided with intake valves C1 to Cm and exhaust valves D1 to Dm, respectively. The internal combustion engine 13 is, for example, a 4-cycle spark ignition internal combustion engine having spark plugs G1 to Gm.

The surge tank 14 is provided with a pressure detector 19 for detecting the intake pipe pressure. The intake pipe 15 is provided with a temperature detector 27 that detects the intake air temperature. The internal combustion engine 13 is provided with a crank angle detector 28 for detecting a crank angle and a valve opening detector 30 for detecting an opening θ of the throttle valve 16. The temperature of the cooling water of the internal combustion engine 13 is detected by the temperature detector 38.

An oxygen concentration detector 21 is provided in the middle of the exhaust pipe 20,
The exhaust gas is purified by the three-way catalyst 22 and discharged to the outside.
Between the exhaust pipe 20 and the surge tank 14, a side passage 23 for recirculating a part of exhaust gas is provided in order to reduce NOx, and this side passage 23 has a recirculation amount. A flow control valve 24 for controlling the valve is interposed. The EGR is realized by the bypass 23 and the flow control valve 24.

A processing device 31 realized by a micro computer or the like includes an input interface 32, an analog / digital converter 33 for converting an input analog signal into a digital signal, a processing circuit 34, an output interface 35, And a memory 36. The memory 36 includes a read-only memory and a random access memory. In an embodiment of the present invention,
In response to the outputs from the detectors 19, 28, 30, 38, etc., the fuel injection amount TAU for each explosion stroke, which is injected from the fuel injection valves B1 to Bm, is controlled.

On the other hand, in the automobile manufacturer, the intake pipe pressure Pm detected by the pressure detector 19 and the basic engine speed Ne per unit time of the internal combustion engine 13 detected by the crank angle detector 28 are basically corresponded. The injection amount TPD is measured, and the measurement result is as shown in FIG. 2, which increases as the rotation speed Ne increases and the intake pipe pressure Pm increases.

Further, the intake air flow rate Q from the throttle valve opening degree θ detected by the valve opening degree detector 30 and the expected delay intake pipe pressure Pmjf obtained as described later, in other words, the air flow rate passing through the slotter valve 16. As shown in FIG. 3A, the measurement result becomes larger as the throttle valve opening θ becomes larger and as the predicted delay intake pipe pressure Pmjf becomes smaller.

Fuel per revolution of the internal combustion engine 13 obtained by dividing the intake air flow rate Q obtained as described above by the number of revolutions Ne of the internal combustion engine 13 per unit time detected by the crank angle detector 28. The predicted intake pipe pressure Pmj is measured from the injection amount Q / Ne and the rotational speed Ne. This expected intake pipe pressure Pmj is
As shown in FIG. 4, the higher the rotation speed Ne,
Further, the larger the injection amount Q / Ne, the larger it becomes.

From the expected intake pipe pressure Pmf obtained in this way,
The delayed expected intake pipe pressure Pmfj ₁ is obtained as shown in the following equation.

The subscript ₁ represents the value at the time of this sampling, _i-1 represents the value at the time of the previous sampling, and the same applies to the following equations. Further, as shown in FIG. 5, the constant n is a value that changes corresponding to the rotation speed Ne, and is selected to be smaller as the rotation speed Ne increases. By properly selecting this constant n, the delayed predicted intake pipe pressure
Pmjf can be blunted to obtain a change characteristic that is substantially close to the actual intake pipe pressure Pm detected by the pressure detector 19.

The experimental results shown in FIG. 2 to FIG.
Stored as a map in. In this way, when the experimental result is stored in the memory 36, when the internal combustion engine 13 is actually used, the throttle valve opening θ changes rapidly due to acceleration, for example, as shown in FIG. 6 (1). , The intake air flow rate Q and the injection amount Q / N change as shown in FIG. 6 (2). As a result, the expected intake pipe pressure Pmj
Changes according to the intake air flow rate Q or the injection amount Q / N as shown by the solid line in FIG. 6 (3), while the delay expected intake pipe pressure Pmjf is ), It changes with a time delay as shown by the broken line.
Further, in FIG. 6 (3), the actual intake pipe pressure Pm detected by the pressure detector 19 changes as shown by the chain double-dashed line.

Therefore, in this embodiment, first, the actual intake pipe pressure Pm detected by the pressure detector 19 and the crank angle detector 28
Revolutions per unit time of internal combustion engine 13 detected by
The basic injection amount TPD is obtained from Ne and the graph shown in FIG. Next, the injection amount TP1 is calculated from the graph shown in FIG. 2 from the predicted intake pipe pressure Pmf and the rotational speed Ne which have good responsiveness, and the injection amount TP2 is calculated from the delayed predicted intake pipe pressure Pmjf and the rotational speed Ne. Obtained, injection amount TP1 and injection amount TP
Find the difference from 2. Then, to the difference thus obtained, an intake delay correction coefficient η corresponding to the capacity of the intake path from the throttle valve 16 of the intake pipe 15 including the surge tank 14 to the intake pipe lines A1 to Am of the combustion chambers E1 to Em, etc. Is calculated to obtain the correction amount TM1, and the actual fuel injection amount TAU is obtained by adding the correction amount TM1 to the basic injection amount TPD and performing correction. That is, TAU = TPD + η (TP1-TP2) = TPD + TM1 (2) As a result, good transient response and steady stability can be obtained, and the air-fuel ratio can always be kept at an optimum value.

FIG. 7 shows the operation for detecting the rotational speed Ne of the internal combustion engine 13. In step s1, the rotational speed Ne detected by the crank angle detector 28 is the analog / digital converter.
It is digitally converted in 33 and read into the processing circuit 34. This operation is performed every time the conversion operation in the analog / digital converter 33 is performed.

FIG. 8 shows the operation for obtaining the basic injection amount TPD,
It is performed every time the actual intake pipe pressure Pm detected by the pressure detector 19 is digitally converted by the analog / digital converter 33. At step s11, the actual intake pipe pressure Pm detected by the pressure detector 19 is read in an analog / digital conversion. At step s12, the basic injection amount TPD corresponding to the rotational speed Ne obtained at step s1 and the intake pipe pressure Pm obtained at step s11 is the second injection amount mentioned above.
It is read from the memory 36 based on the map shown.

FIG. 9 shows the operation for obtaining the predicted intake pipe pressure Pmj, and every time the throttle valve opening θ detected by the valve opening detector 30 is digitally converted by the analog / digital converter 33. To be done. At step s21, the throttle valve opening .theta. Detected by the valve opening detector 30 is read by analog / digital conversion. At step s22, the throttle valve opening θ obtained at step s21 and
Delayed expected intake pipe pressure Pmj obtained in step s31 described later
From f and f, the intake air flow rate Q is read from the map in the memory 36 based on the graph shown in FIG. In step s23, the injection amount Q / Ne is calculated from the intake air flow rate Q obtained in step s22 and the rotational speed Ne. In step s24, the injection amount obtained in step s23
From Q / Ne and rotation speed Ne, based on the graph shown in FIG. 4, the expected intake pipe pressure is calculated from the map in memory 36.
Pmj is read.

FIG. 10 shows the operation for obtaining the delayed predicted intake pipe pressure Pmjf, which is performed, for example, every 4 msec. In step s31, the constant n is read from the map in the memory 36 from the rotational speed Ne based on the graph shown in FIG. 5, and in step S32, the predicted delayed intake pipe pressure is calculated based on the first equation. Pmjf ₁ is required.

FIG. 11 shows an operation for obtaining the actual fuel injection amount TAU, which is performed, for example, for each stroke of the internal combustion engine 13. At step s41, the expected intake pipe pressure obtained at step s24
The injection amount TP1 (corresponding to the first state amount) is read from the map in the memory 36 based on the graph shown in FIG. 2 from Pmj and the rotation speed Ne obtained at step s1. In step s42, the injection amount TP2 (corresponding to the second state amount) is stored in the map in the memory 36 based on the above-mentioned FIG. 2 based on the delay expected intake pipe pressure Pmjf obtained in step s32 and the rotational speed Ne. Read from. At step s43, the actual fuel injection amount TAU is calculated from the injection amount TP1 obtained at step s41 and the injection amount TP2 obtained at step s42 based on the second equation.

As described above, in the present embodiment, the basic injection amount TPD is corrected by the correction amount TM1 obtained based on the injection amounts TP1 and TP2. Therefore, as shown in FIG. , The estimated intake pipe pressure Pmjf and the expected intake pipe pressure
It is consistent with Pmj, and therefore the injection amount calculated using these predicted intake pipe pressure Pmj and delayed predicted intake pipe pressure Pmjf
TP1 and TP2 are consistent in the steady state. Therefore, good stability can be obtained in a steady state without strict measurement of the intake air flow rate Q, and similarly good stability can be obtained even when the atmospheric pressure changes greatly. You can Therefore, the accuracy of the valve opening detector 30 does not need to be so high, and the air-fuel ratio can always be kept constant by absorbing the mounting error of the valve opening detector 30 and the like.

In the above-described embodiment, the correction amount TM1 is obtained by using the injection amounts TP1 and TP2 per explosion stroke, but as another embodiment of the present invention, the expected intake pipe pressure Pm is set as the first state amount.
j may be used as the second state quantity, and the delayed predicted intake pipe pressure PPmjf may be used to obtain, that is, TAU = TPD + η * K * (Pmj-Pmjf) (3) where K is the predicted intake pipe pressure Pmj. And a conversion coefficient for obtaining the injection amount from the estimated delay intake pipe pressure Pmjf, which may be a constant value or a value that changes depending on the rotational speed Ne.

Further, the correction amount TM1 may be obtained based on the intake air flow rate Q. In this case, if the injection amount Q / Ne is QN,
Delayed injection amount QNf It is possible to obtain from this delay injection amount QNf and injection amount QN
The actual fuel injection amount TAU may be obtained from and as shown in the following equation.

TAU = TPD + ηK (QN-QNf) = TPD + TM1 (5) The delayed injection amount QNf becomes larger as the intake air flow rate Q becomes larger and the throttle valve opening θ becomes larger as shown in FIG. 3 (2). It gets bigger.

FIG. 12 is a sectional view of the vicinity of the surge tank 14 for explaining the concept of another embodiment of the present invention. Throttle valve 16
At the time of acceleration, the intake air passing through the inside of the surge tank 14 fills the surge tank 14 with high-density air and then flows out to the intake pipe lines A1 to Am as shown in FIG. 12 (1). On the other hand, at the time of deceleration, as shown in FIG. 12 (2), even if the intake air flow rate through the throttle valve 16 decreases, the high-density air in the surge tank 14 flows out to the intake pipe lines A1 to Am. To do. Therefore, in this embodiment, the surge tank 14 and the intake pipe
The actual fuel injection amount TAU is determined as follows in consideration of the influence of the intake passage extending from the downstream side of the throttle valve 16 of 15 to the intake pipe lines A1 to Am.

That is, by dividing the intake air flow rate Q shown in FIG. 3 (3) from the state quantity TP2 (second state quantity) and the throttle valve opening θ obtained as described below by the rotation speed Ne. The injection quantity Q / Ne obtained as a result is set as the state quantity PT1 (first state quantity), and the state quantity TP2 is set as And the constant w is selected to be an appropriate value of, for example, about 30 to 40, the state quantity TP2 is shown in FIG. 6 (3) as shown by the broken line in FIG. 6 (3). It is possible to have a change close to the actual intake pipe pressure Pm indicated by the two-dot chain line. This state quantity TP2 is, for example, 4 to 5
Updated every msec sampling operation.

The correction for the intake path including the surge tank 14 is performed as follows. When the throttle valve opening θ changes due to acceleration as shown in FIG. 13 (1), the intake pipe pressure Pm changes as shown in FIG. 13 (2), and the state quantity is changed accordingly. TP1 and TP2 respectively change as shown by the solid line and the broken line in FIG. 13 (3). This FIG. 13 shows the change in the relatively lowland where the atmospheric pressure is around 760 mmHg.

On the other hand, in the highland, as shown in FIG. 14 (1), the intake pipe pressure Pm changes as shown in FIG. 14 (2) for the same change in the throttle valve opening θ, Further, the state quantities TP1 and TP2 change as shown by the solid and broken lines in FIG. 14 (3).

As is clear from FIGS. 13 and 14, the time change rate ΔPm of the intake pipe pressure Pm is smaller in the highlands, whereas the state quantities TP1 and TP2 are almost equal to those in the lowlands even in the highlands. Change. Therefore, if the correction amount TM1 is used for correction, excessive correction will be performed in high altitudes where the air density is low.

Therefore, the capacity of the intake path is set to V, and the correction amount TM2 is obtained by using the change amount ΔTP2 of the capacity V per unit time,
The actual fuel injection amount TAU is obtained by correcting the basic injection amount TPD together with the correction amount TM1 obtained from the state amounts TP1 and TP2.

TAU = TPD + η * K (TP1-TP2) -V * ΔTP2 = TPD + TM1-TM2 (7) FIG. 15 shows the operation for obtaining the correction amount TM1, and the throttle detected by the valve opening detector 30. It is performed every time the valve opening θ is analog / digital converted. At step u21, the throttle valve opening θ detected by the valve opening detector 30 is read in an analog / digital conversion. At step u22, the throttle valve opening θ obtained at step u21 and the state quantity obtained as described later
Intake air flow rate Q shown in Fig. 3 (3) from TP2
Are read from the memory 36. In step u23, the intake air flow rate Q obtained in step u22 is divided by the rotation speed Ne obtained in step s1 to obtain the state quantity TP1. At step u24, the difference between the state quantity TP1 obtained at step u23 and the state quantity TP2 obtained as described later, the suction efficiency η, and the injection quantity conversion coefficient K are corrected as shown by the following equation. The quantity TM1 is required.

TM1 = η * K * (TP1-TP2) (8) FIG. 16 shows an operation for obtaining the state quantity TP2, which is performed, for example, every 4 msec. At step u31, the state quantity TP2 is obtained based on the above equation 6 using the state quantity TP1 obtained at the step u23.

FIG. 17 shows the operation for obtaining the correction amount TM2, which is performed, for example, every 20 mesc. In step u41, the difference between the state quantity TP2 during the current sampling, the state quantity TP2 ₀ at 20msec previous previous sampling, i.e. a unit time 20ms
The change amount ΔTP2 of the state amount TP2 per ec is calculated, and the step
At u42, the change amount ΔTP2 obtained at step 41 and the capacity V of the intake path are calculated to obtain the correction amount TM2.

FIG. 18 shows an operation for obtaining the actual fuel injection amount TAU, which is performed, for example, for each stroke of the internal combustion engine 13. At step u51, the basic injection amount obtained at step s12
The TPD is corrected by the correction amount TM1 obtained in step u24 and the correction amount TM2 obtained in step u42 to obtain the actual fuel injection amount TAU. In this way, the fuel injection amount TAU can be obtained in consideration of the response delay due to the intake path including the surge tank 14 and the change in intake air due to the change in atmospheric pressure.

In each of the above-described embodiments, the combustion air flowing into each of the intake pipes A1 to Am was considered to be supplied only through the throttle valve 16, but in reality, it corresponds to the load applied to the internal combustion engine 13. The processing device 31 is a flow control valve provided in the side passage 23.
The EGR is performed by connecting / disconnecting 24. Therefore, even if the same throttle valve opening θ is stored in the memory 36,
As shown in the figure, a map of the intake air flow rate Q corresponding to the state quantity TP2 is stored. In FIG. 19, the solid line 1 is the intake air flow rate when the EGR is OFF when the flow control valve 24 is closed, that is, The change in the fresh air intake flow rate Q1 through the throttle valve 16 is shown, and the broken line l2 indicates that the flow control valve 24 has opened.
When the EGR is ON, the sum of the intake air flow rate, that is, the fresh air intake flow rate Q1 and the exhaust gas recirculation amount Q2 through the side passage 23 is shown.
In this way, by changing the map value of the intake air flow rate Q read from the memory 36 in response to the EGR ON / OFF operation, the actual fuel injection amount TAU can be accurately adjusted to correspond to the fresh air intake flow rate Q1. Can be maintained at any value.

However, the read operation of the map value as described above is
At the EGR ON / OFF times t1 and t2 shown in FIG. 20 (1), the switching is immediately performed, and accordingly, the basic injection amount TP is set.
D changes as shown in Fig. 20 (2), and EGR is OFF
Immediately after the time t1 when the ON state is changed to the ON state, the air-fuel ratio becomes the lean state because the exhaust gas recirculation amount Q2 through the side passage 23 is small, while at the time t2 when the EGR changes from the ON state to the OFF state. The exhaust gas recirculation amount Q2 does not immediately become zero, so that the air-fuel ratio becomes the latch state. The intake pipe pressure Pm during the ON / OFF operation of the EGR changes as shown in FIG. 20 (3). Therefore, EGR O like this
At the time of switching the N / OFF state, it is desirable to perform the transient correction as shown by the broken line in FIG. 20 (2), and in this embodiment, the transient correction is performed as follows.

That is, first, the state quantity TP1 obtained by dividing the intake air flow rate Q obtained as described above and the rotation speed Ne is obtained, and then the state quantity TP2 is obtained as shown in the sixth equation. Ask for. State quantity T thus obtained
When the throttle valve opening θ changes as shown in FIG. 21 (1), P1 and TP2 change as shown by a solid line and a broken line in FIG. 21 (2), respectively.

As is clear from FIG. 21 (2), the state quantity TP1 follows the change in the throttle valve opening θ, and the state quantity TP2 shows a stable change which is the state quantity TP1. Therefore, the actual fuel injection amount TAU is obtained from these two state quantities TP1 and TP2 as shown in the above-mentioned second equation.

However, in this case, the basic injection amount read from the memory 36
The map value of TPD is the EGR value shown by the solid line in FIG.
When the engine is off and when the EGR, which is indicated by the broken line in FIG. 22, is different from each other, that is, when the internal combustion engine 13 has the same rotational speed, for example, Ne1, when the EGR is off, the EGR
The basic injection amount TPD is made larger than that at the time of ON.

Therefore, when the EGR is changed from the OFF state to the ON state at the time t1 as shown in FIG. 23 (1), the basic injection amount TPD changes as shown in FIG. As shown in Fig. 24, the value of a relatively large injection amount when EGR is OFF
From P1, through a value P2 that is a relatively small injection amount when EGR is ON at the same intake pipe pressure Pm1 and the same rotation speed Ne1, the intake pipe pressure Pm shown in Fig. 23 (2) rises. Accordingly, the steady-state value P3 is reached. The change in the intake air flow rate Q at this time is shown by the reference numeral P1a in FIG.
When the state quantity TP2 does not change from the hour value, the reference mark P2a
To reach the steady-state value indicated by reference sign P3a. At this time, the changes in the state quantities TP1 and TP2 are
In FIG. 4 (4), it is shown by a solid line and a broken line, respectively.

Further, as shown in FIG. 26 (1), EG at time t2
When R changes from the ON state to the OFF state, the basic injection amount TPD changes as shown in (3) of the same figure, and its locus is relatively low when EGR is OFF, which is indicated by reference numeral P4 in FIG. 27. From the values, EG at the same intake pipe pressure Pm1 and rotation speed Ne1
Through the value P5 when R is OFF, the steady-state value indicated by reference numeral P6 in FIG. 27 is reached as the intake pipe pressure Pm shown in FIG. 26 (2) decreases. At this time, the intake air flow rate Q changes from the relatively high value when the EGR is ON, which is indicated by the reference sign P4a in FIG. 28, and when the state quantity TP2 does not change, the EGR
After reaching the value P5a at the time of OFF, the value P6a at the steady state is reached. Changes in the state quantities TP1 and TP2 at this time are shown by a solid line and a broken line in FIG. 26 (4), respectively.

Thus, as is clear from FIGS. 23 and 26,
At the time t1 when the EGR changes from the OFF state to the ON state, the basic injection amount TPD decreases and the state amount TP1 increases. Further, at the time t2 when the EGR is changed from the ON state to the OFF state, the basic injection amount TPD increases, whereas the state amount TP1 decreases.

FIG. 29 shows the operation for obtaining the basic injection amount TPD,
It is performed every time the intake pipe pressure Pm detected by the pressure detector 19 is digitally converted by the analog / digital converter 33. At step r11, the actual intake pipe pressure Pm detected by the pressure detector 19 is read by being converted from analog to digital. At step r12, it is determined whether EGR is ON, that is, whether the flow control valve 24 is open. If so, at step r13 the above step s
The basic injection amount TPD is read from the memory 36 based on the rotation speed Ne obtained in 1 and the intake pipe pressure Pm obtained in step r11 based on the map shown by the broken line in FIG. When EGR is OFF at step r12, the basic injection amount TPD is read from the memory 36 at step r14 based on the map shown by the solid line in FIG.

FIG. 30 shows an operation for obtaining the correction amount TM1, which is performed every time the throttle valve opening θ detected by the valve opening detector 30 is analog / digital converted. At step r21, the throttle valve opening θ detected by the valve opening detector 30 is read in an analog / digital conversion. In step r22, it is judged whether or not EGR is ON, and if so, the process moves to step r23, where step r23
The throttle valve opening θ obtained in step 21 and the step u3
A map value of the intake air flow rate Q when the EGR is ON, which is indicated by a broken line in FIG. 19, is read from the memory 36 from the state quantity TP2 obtained in 1 above, and the routine proceeds to step r24. Step r
When the EGR is OFF at 22, the routine proceeds to step r25, where the map value of the intake air flow rate Q when the EGR is OFF shown by the solid line in FIG. 19 is read from the memory 36 and then proceeds to step r24. At step r24, the state quantity TP1 is calculated from the intake air flow rate Q read at steps r23 and r25 and the rotation speed Ne obtained at step s1.
Then, the correction amount TM1 is obtained from the state amount TP1 obtained in step r24, the state TP2 obtained in step u31, the suction efficiency η, and the injection amount conversion coefficient K based on the above equation (8).

FIG. 31 shows an operation for obtaining the actual fuel injection amount TAU, which is performed, for example, for each stroke of the internal combustion engine 13. At step r51, the actual fuel injection amount TAU is obtained based on the second equation from the basic injection amount TPD read at step r13 or r14 and the correction amount TM1 obtained at step r26.

In this way, even during the transition of EGR ON / OFF,
By correcting the basic injection amount TPD with the correction amount TM1 obtained based on the state amounts TP1 and TP2, that is, by obtaining the actual fuel injection amount TAU based on the second equation,
The optimum fuel injection amount TAU can be obtained according to the change in the fresh air intake flow rate Q1, and the air-fuel ratio can always be kept stable.

According to the fuel injection amount control method of the first aspect of the present invention, the basic injection amount is obtained using the intake pipe pressure. Further, the first state quantity related to the intake air flow rate passing through the throttle valve is obtained, and the first state quantity related to the intake air flow rate supplied to the internal combustion engine is changed so as to follow the first state quantity with a time delay. The two-state amount is obtained, the correction amount is obtained based on the difference between the first state amount and the second state amount, and the actual fuel injection amount is obtained from the basic injection amount and the correction amount. Since the first state quantity used to obtain the correction amount is virtually obtained using the opening degree of the throttle valve and the second state quantity, in the steady state, the first state quantity and the second state quantity are used. Since the amounts are substantially the same, the correction amount can be accurately obtained. Further, when obtaining the first state quantity, the first state quantity relating to the intake air flow rate passing through the throttle valve and the second state quantity which changes following the first state quantity with a time delay are utilized. The opening degree of the throttle valve has good responsiveness, and therefore, the correction amount can be obtained with good responsiveness.

Further, according to the fuel injection amount control method of the second aspect of the present invention, the second state amount is the injection amount obtained by using the delayed expected intake pipe pressure, and the first state amount is obtained from the expected intake pipe pressure. It is the injection amount, and the correction amount can be accurately obtained by using these injection amounts.

According to the fuel injection amount control method of the third aspect of the present invention, the second state quantity is the delayed expected intake pipe pressure, and the first state quantity is
The state quantity is the predicted intake pipe pressure, and the correction amount can be accurately obtained from the difference between the predicted intake pipe pressure and the delayed predicted intake pipe pressure.

Further, according to the fuel injection amount control method of claim 4 (or 5) of the present invention, the basic injection amount is obtained by using the intake pipe pressure, and the first state amount related to the intake air flow rate passing through the throttle valve. Is obtained as an injection amount (or an expected intake pipe pressure) based on the expected intake pipe pressure, and a second state quantity related to the intake air flow rate supplied to the internal combustion engine is an injection amount based on the delayed expected intake pipe pressure. (Or a delay expected intake pipe pressure) is obtained so as to follow the first state quantity with a time delay, and a correction amount is obtained based on the difference between the first state quantity and the second state quantity. The actual fuel injection amount is obtained from the injection amount and the correction amount. Then, the first state quantity and the second state quantity used for obtaining the correction amount are the injection quantity based on the predicted intake pipe pressure (or the predicted intake pipe pressure) and the injection based on the delayed predicted intake pipe pressure, respectively. Since it is virtually determined by the amount (or the estimated intake pipe pressure delay), in the steady state, the first state amount and the second state amount substantially match, and the correction amount can be accurately obtained. it can. Further, when obtaining the correction amount, the injection amount based on the predicted intake pipe pressure (or the predicted intake pipe pressure) is used as the first state amount, and the injection amount based on the delayed predicted intake pipe pressure (or the delayed predicted intake pressure) is used as the second state amount. The injection amount based on the predicted intake pipe pressure (or the predicted intake pipe pressure) has a good responsiveness, and therefore the fuel injection amount can be obtained with a high responsiveness.

Further, according to the fuel injection amount control method of the sixth aspect of the present invention, the intake air flow rate passing through the throttle valve is obtained by using the opening degree of the throttle valve and the second state amount, and the new amount of air passing through the throttle valve is obtained. Since the total intake air flow rate is the sum of the air intake flow rate and the exhaust gas recirculation flow rate, the start of exhaust gas recirculation (ON) /
It is possible to suppress fluctuations in the air-fuel ratio even during the transition of termination (OFF).

Further, according to the fuel injection amount control method of claim 7 of the present invention, the basic injection amount is obtained by using the intake pipe pressure, and the first state amount related to the intake air flow rate passing through the throttle valve is obtained. A second state variable that follows the first state quantity with a time delay and is related to the flow rate of intake air supplied to the internal combustion engine.
State quantity is required. Then, the first correction amount is obtained based on the difference between the first state amount and the second state amount, and the second correction amount related to the second state amount and the capacity of the intake path is obtained. The actual fuel injection amount is obtained from the amount and the first and second correction amounts. In this way, in addition to the first correction amount, the correction is performed by the second correction amount that takes into consideration the intake delay due to the intake path, the atmospheric pressure correction at high altitude, etc.
The actual fuel injection amount can be controlled with higher accuracy.

[Brief description of the drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, and FIG. 2 is a graph showing the relationship between the intake pipe pressures Pm, Pmj, Pmjf and the injection amounts TPD, TP1, TP2 at each rotational speed Ne of the internal combustion engine 13, Fig. 3 shows the estimated intake delay pipe pressure Pmjf at each throttle valve opening θ.
A graph showing the relationship between the delayed injection amount QNf or the state amount TP2 and the intake air flow rate Q. FIG. 4 shows the injection amount Q / at each rotation speed Ne.
FIG. 5 is a graph showing the relationship between Ne and the expected intake pipe pressure Pmj. FIG. 5 is a graph showing the change in the constant n with respect to the change in the rotational speed Ne.
FIG. 6 is a waveform chart for explaining the operation of one embodiment of the present invention, FIGS. 7 to 11 are flow charts for explaining the operation of one embodiment of the present invention, and FIG. 12 is the present invention. A cross-sectional view of a surge tank 14 showing the flow of intake air for explaining the operation of another embodiment, FIGS. 13 and 14 are waveform charts for explaining the operation of another embodiment of the present invention, 15 to 18 are flow charts for explaining the operation of another embodiment of the present invention shown in FIGS. 12 to 14, and FIG. 19 is a principle of still another embodiment of the present invention. 20 and 21 are graphs showing changes in the intake air flow rate Q when the EGR is turned ON / OFF to explain
The figure is a timing chart for explaining the operation of the embodiment shown in FIG. 19, and FIG. 22 shows the relationship between the intake pipe pressure Pm and the basic injection amount TPD when the EGR is ON and when it is OFF. Graph, FIG. 23 is a waveform diagram for explaining the operation shown in FIGS. 20 and 21, and FIG. 24 is a graph showing the locus of the basic injection amount TPD during the operation shown in FIG. No. 2
Fig. 5 shows the intake air flow rate Q during the operation shown in Fig. 23.
FIG. 26 is a waveform diagram for explaining the other operation shown in FIGS. 20 and 21, and FIG. 27 is a graph showing the locus of FIG.
FIG. 28 is a graph showing the locus of the basic injection amount TPD during the operation shown in the figure, FIG. 28 is a graph showing the locus of the intake air flow rate Q during the operation shown in FIG. 26, and FIGS. First
19 is a flow chart for explaining the operation of still another embodiment of the present invention shown in FIGS. 19 to 28. 13 ... internal combustion engine, 14 ... surge tank, 15 ... intake pipe,
16 …… Slottle valve, 19 …… Pressure detector, 27,38 …… Temperature detector, 20 …… Exhaust pipe, 23 …… By-pass, 24 …… Flow control valve, 28 …… Crank angle detector, 30 ...... Valve opening detector, 31
...... Processor, 36 …… Memory, A1 to Am …… Intake line, B1
~ Bm ...... Fuel injection valve, E1 ~ Em ...... Combustion chamber, G1 ~ Gm ...... Spark plug

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location F02M 25/07 550 F02M 25/07 550R (56) Reference JP-A 63-215848 (JP, A) ) JP-A 1-216054 (JP, A) JP-A 1-216041 (JP, A) JP-A 1-2711642 (JP, A) JP-A 1-216054 (JP, A) JP-A 1- 106959 (JP, A) JP 62-206244 (JP, A) JP 63-8028 (JP, A) JP 62-258137 (JP, A) Actual Kaihei 1-160148 (JP, U)

Claims (7)

(57) [Claims] 1. A basic injection amount is obtained by using an intake pipe pressure to obtain a first state quantity related to an intake air flow rate passing through a throttle valve, and the first state quantity is tracked and changed with a time delay. The second related to the intake air flow rate supplied to the internal combustion engine
The state quantity is obtained, and when the first state quantity is obtained, the opening amount of the throttle valve and the second state quantity are used, and the correction quantity is obtained based on the difference between the first state quantity and the second state quantity, A method for controlling a fuel injection amount of an internal combustion engine, characterized in that a fuel injection amount is obtained from the basic injection amount and the correction amount. 2. The second state quantity is an injection quantity obtained by using a delayed expected intake pipe pressure, and the first state quantity is an injection quantity obtained from the expected intake pipe pressure. A fuel injection amount control method for an internal combustion engine according to claim 1. 3. The second state quantity is a delayed predicted intake pipe pressure, the first state quantity is a predicted intake pipe pressure, and the correction amount is the predicted intake pipe pressure and the delayed predicted intake pipe pressure. The fuel injection amount control method for an internal combustion engine according to claim 1, wherein the method is obtained from a difference with the pressure. 4. A basic injection amount is obtained using the intake pipe pressure, and a first state amount related to the intake air flow rate passing through the throttle valve is obtained as an injection amount based on the predicted intake pipe pressure, and is supplied to an internal combustion engine. The second state quantity related to the intake air flow rate is determined as the injection quantity based on the delay predicted intake pipe pressure so as to follow the first state quantity with a time delay, and the first state quantity and the A fuel injection amount control method for an internal combustion engine, comprising: obtaining a correction amount based on a difference from a second state amount; and obtaining a fuel injection amount from the basic injection amount and the correction amount. 5. A basic injection amount is obtained by using the intake pipe pressure, and a first state quantity related to the intake air flow rate passing through the throttle valve is obtained as a predicted intake pipe pressure, and the intake air flow rate supplied to the internal combustion engine. A second state quantity related to the above is obtained as a delayed predicted intake pipe pressure so as to follow the first state amount with a time delay, and based on a difference between the predicted intake pipe pressure and the delayed predicted intake pipe pressure. A fuel injection amount control method for an internal combustion engine, comprising: obtaining a correction amount by calculating the fuel injection amount from the basic injection amount and the correction amount. 6. The intake air flow rate passing through the throttle valve is obtained by using the opening degree of the throttle valve and the second state quantity, and the fresh air intake flow rate passing through the throttle valve and the exhaust gas recirculation flow rate are calculated. The fuel injection amount control method for an internal combustion engine according to any one of claims 1 to 5, wherein the sum total intake air flow rate is used. 7. A basic injection amount is obtained by using the intake pipe pressure, a first state amount related to an intake air flow rate passing through a throttle valve is obtained, and the first state amount is followed and changed with a time delay, A second state quantity related to the flow rate of intake air supplied to the internal combustion engine is obtained, and a first state quantity is calculated based on a difference between the first state quantity and the second state quantity.
A correction amount is obtained, a second correction amount related to the second state amount and the capacity of the intake path including the surge tank is obtained, and a fuel injection amount is obtained from the basic injection amount and the first and second correction amounts. A method for controlling a fuel injection amount of an internal combustion engine, comprising: