JPH01290940A - Fuel injection amount control system of internal combustion engine - Google Patents

Abstract

PURPOSE:To suppress variation in the air fuel ratio at transient by determining the condition amount associate with the flow rate of suction air, determining another condition amount varying in following-up so as to be approx. identical the first- mentioned condition amount with a certain delay, and calculating the correction injection amount from the difference between them. CONSTITUTION:The CPU 34 of a processing device 31 calculates the fundamental injection amount TPD from the number of engine revolutions due to signals from a crank angle sensor 28 and the suction pipe pressure due to a pressure sensor 19. This is followed by determination of the condition amount TP1 of the injection amount etc. determined with the suction pipe pressure anticipated from the number of revolutions under the atmospheric pressure, for ex., which is decided previously relating to the suction air flow rate Q, and then the condition amount TP2 of injection amount etc. determined from, for ex., the delay anticipant suction pipe pressure, which varies in following-up after this TP1 with a certain delay, is determined. Then the correction injection amount TM1 is determined on the basis of the difference between the condition amounts TP1, TP2, which is used to correction of the fundamental injection amount TPD, followed by deciding the actual fuel injection amount. Thus variation in the air fuel ratio can be suppressed even at transient.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for controlling the fuel injection amount of an internal combustion engine.

Conventional technology In so-called electronically controlled fuel injection devices for internal combustion engines,
In a typical conventional technique, the intake pipe pressure P, m, etc. is 71 times smaller than the rotational speed Ne per unit time of the internal combustion engine!
JitT PD was used as the actual fuel injection amount TAL1. Therefore, during a transient period when the throttle valve opening changes rapidly, the intake pipe pressure Pm slowly increases due to the influence of the capacity of the intake path from the downstream side of the throttle valve including the surge tank to the intake pipe of each combustion chamber. Therefore, while the fuel injection tTAU is stable,
There may be a delay in response.

In the method previously proposed by the applicant to solve this problem, the intake air flow! The actual fuel injection IETAU is obtained by correcting the state filTPD using the state quantity TPQ obtained from Q and the rotational speed Ne, improving responsiveness.

Problems to be Solved by the Invention However, in this method, the states ITPD and TPQ, which should match in a steady state other than the above-mentioned transient state, are converted into matching errors, that is, the map values of these state quantities, TPD, and TPQ, for example, in the exhaust gas. The air-fuel ratio is not stable because the air-fuel ratio does not necessarily match due to errors that occur when rewriting is performed by learning according to the oxygen concentration in the fuel, changes in charging efficiency, etc.

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 1Q1- and the exhaust gas recirculation 1:Q2. Even if the intake air flow ff1Q is constant, the fresh air intake flow rate QI is different between when R is ON and when R is OFF. Therefore, in the conventional technology, 1 TAU of fuel injection is
For example, when the power is turned on, the decrease of several percent compared to when the power is turned off is dealt with by switching the map without reading the state 9JiTPQ. Therefore, if such a map switching operation is performed at the same time as the EGR 0N10FF operation, the air-fuel ratio will deviate during the transient period until the recirculation amount Q2 stabilizes.

The purpose of the present invention is to
An internal combustion engine that has good response characteristics during transitions such as ON and OFF, and good stability during steady state, making it possible to always maintain the air-fuel ratio at the optimum value. An object of the present invention is to provide a fuel injection amount control method.

Means for Solving the Problems The present invention calculates the basic injection ITPD from the rotational speed Ne per unit time of the internal combustion 8i leap and the actual intake pipe pressure Pm, and calculates the state quantity TP1 related to the intake air flow rate Q of the internal combustion engine. Find a state quantity TP2 that follows and changes to match or almost match the state quantity TPI with a time delay, and find a corrected injection amount TMI based on the difference between the state quantity TPI and the state quantity TP2. This is a fuel injection amount control method for an internal combustion engine, characterized in that an actual fuel injection amount T A tJ is determined from the basic injection amount TPD and the corrected injection amount TM1.

The present invention also provides a fuel injection amount control method for an internal combustion engine, wherein the intake air flow ff1Q is determined from the opening degree θ of a throttle valve that supplies combustion air to the internal combustion engine and the condition R11TP2. be.

Furthermore, the present invention provides that the state TP2 is the state quantity T.
Let P2 be the injection amount determined from the delayed expected intake pipe pressure Pmjf, and the above condition! l)! 1TP1 is the expected intake pipe pressure Pm
When the injection amount is determined from j, the state! This is a fuel injection amount control method for an internal combustion engine, which is characterized in that the fuel injection amount is corrected so as to approach JITPI.

Further, in the present invention, the intake air flow ff1Q is equal to the throttle valve opening θ and the state ff! The fresh air intake flow J! is determined from tiTP2 and flows through the throat valve. This is a fuel injection amount control system for an internal combustion engine characterized in that the total intake flow rate is the sum of tQ1 and exhaust gas recirculation ff1Q2.

Furthermore, the present invention calculates the basic injection amount TPD from the rotational speed Ne per unit time of the internal combustion engine and the actual intake pipe pressures P and m.
Find the state JUTP related to the intake airflow of the internal combustion engine, fiQ.
], find the state quantity Tp2 that follows and changes so that it matches 1 or almost matches the state 1TP1 with a time delay, and based on the difference between the state quantity TPI and the state R, II T P 2 Calculate the corrected injection amount TMI and use the above condition nJ! A corrected injection amount TM2 is determined in relation to LTP2 and the capacity of the intake path including the surge tank, and the corrected injection amount TM1. This is a fuel injection amount control method for an internal combustion engine characterized by determining the actual fuel injection ITAtJ from TM2.

According to the present invention, first, the basic injection amount TPD is determined from the rotational speed Ne per unit time of the internal combustion engine and the actual intake pipe pressure Pm. Next, conditions nji related to the intake air flow rate Q, such as the injection amount determined from the intake pipe pressure Pmj predicted from the rotational speed Ne under a predetermined atmospheric pressure.
TP1 is obtained, and the state quantity Ijl is changed to follow TP1 with a time delay, for example, delayed expected intake pipe pressure Pmjf
The state quantity TP2 such as the injection amount determined from the above is determined. Subsequently, a corrected injection amount "rM1" is determined based on the difference between the state JITPI and the state R amount TP2, and the basic injection amount TPD is corrected by this corrected injection ITMI to determine the actual fuel injection amount TAU.

That is, based on the stable basic injection amount TPD, it is determined from the difference between the state quantity TP corresponding to changes in the intake air flow MQ and the state quantity TP2 that follows the state quantity TPI with a time delay. By correcting with the corrected injection amount TMI with good response, it is possible to obtain the fuel injection amount TAU with good steady stability and transient response.

Further, by correcting the state quantity TP2 so as to approach the state fiJITP1 during steady state, stability during steady state can be further improved.

Furthermore, the intake air flow rate Qt, the throttle valve opening degree θ
and the state quantity TP2, and the intake air flow MkQ thus determined is the fresh air intake flow rate Q through the throttle valve.
1 and the exhaust gas recirculation amount Q2. Therefore, by using the state quantity TP2 in this way, it is possible to suppress fluctuations in the air-fuel ratio even during the transient period when the EGR is 0N10FF. I can do it.

Further, according to the present invention, the basic injection IET is first determined from the rotational speed Ne per unit time of the internal combustion engine and the actual intake pipe pressure Pm.
Determine PD, then determine the state JiTP1 related to the intake air flow rate Q, for example, the intake pipe pressure Pmj expected from the rotation speed Ne under a predetermined atmospheric pressure,
This situation i! A state quantity 1T, such as delayed expected intake pipe pressure Pmjf, that changes to follow JiTP1 with a time delay.
Find P2. Next, a corrected injection amount TMI is determined based on the difference between the state quantity TPI and the state quantity TP2, and a corrected injection amount TM2 is determined in relation to the state quantity TP2 and the capacity of the intake path including the surge tank. Basic injection jtTP
The actual fuel injection amount TAU is determined by correcting D using these corrected injection amounts TM1 and TM2.

In other words, based on the stable basic injection amount TPD, the actual fuel injection JLTAU is determined in response to changes in the intake air flow rate Q, with good responsiveness and taking into account the intake delay due to the intake path. You can ask for it.

Embodiment FIG. 1 is a block diagram of an 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 to these combustion chambers E1 to Em from an intake pipe 15. A throttle valve 16 is interposed in the intake pipe 15. Combustion air via the throttle valve 16 is guided from the surge tank 14 to intake pipes A1 to Am provided individually for each combustion chamber E1-Em. Each intake pipe A1 to Am is provided with a fuel injection valve 81 to Bm, respectively, and in each explosion stroke in each combustion chamber E1 to Em, a fuel injection amount TAU determined by a processing device 31 to be described later is applied. In each combustion chamber E1 to Em where injection is performed,
Intake valves C, 1 to Cm and exhaust valves D1 to Dm are provided, respectively. The internal combustion engine 13 includes, for example, spark plugs G1 to
A pressure detector 19 for detecting the intake pipe pressure is provided in the four thermosurge tank 14 having the Gm. The intake pipe 15 is provided with a temperature detector 27 that detects intake air temperature. The internal combustion engine 13 is provided with a crank angle detector 28 for detecting the crank angle, and the throttle valve 1
A G valve gap detector 30 is provided to detect the opening degree θ of 6. The temperature of the cooling water of the internal combustion engine 13 is measured by the temperature detector 3.
8.

An oxygen concentration detector 21 is provided in the middle of the exhaust pipe 20, and the exhaust gas is purified by a three-way catalyst 22 and discharged to the outside.
In order to reduce the
A flow control valve 24 is interposed to control the amount of recirculation. The EGR is realized by these side passages 23 and flow control valve 24.

A processing device 31 realized by a microcomputer or the like includes an input interface 32, an analog/digital converter 33 that converts an input analog signal into a digital signal, a processing circuit 3.1, and an output interface 3.
5 and memory 36, memory 36 includes read-only memory and random access memory. In the embodiment of the present invention, the mP1 injection pattern TAU for each explosion stroke injected from the fuel injection valves 81 to Bm is controlled in response to outputs from the detectors 19, 28, 30, 38, etc.

On the other hand, the automobile manufacturer uses the intake pipe pressure Pm detected by the pressure detector 19 and the rotation speed N per unit time of the internal combustion engine 1.3 detected by the crank angle detector 28.
The basic injection amount TPD is measured corresponding to e, and the measurement result is shown in FIG. 2, and increases as the rotational speed Ne increases and as the intake pipe pressure Pm increases.

In addition, the intake air flow rate Q is measured from the throttle valve opening θ detected by the valve opening detector 30 and the delayed expected intake pipe pressure Pmjf obtained as described later, and the measurement results are shown in Fig. 3 (1). ), the larger the throttle valve opening θ, the larger the delayed expected intake pipe pressure Pm.
The lower jf becomes, the larger it becomes.

The internal combustion engine 13 is determined by dividing the intake air flow rate Q determined as described above by the rotational speed Ne per unit time of the internal combustion engine 13 detected by the crank angle detector 28.
The expected intake pipe pressure Pmj is measured from the fuel injection amount Q/N e per rotation and the rotation speed Ne. As shown in FIG. 4, this expected intake pipe pressure Pmj increases as the rotation 11N e increases
/ The larger the Ne, the larger it becomes.

The expected intake pipe pressure P IITj obtained in this way
From, the delayed expected intake pipe pressure P is calculated as shown by the following formula.
mjft is calculated7 Pmj f l=Pm j f I-1±-(Pm
j l-Pm,) f,-,)-(1) The subscript represents the value at the current sampling time,
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 in accordance with the rotational speed Ne, and is selected to be smaller as the rotational speed Ne increases. By appropriately selecting this constant n, the retarder and old intake pipe pressure Pmjf3 can be smoothed to have a change characteristic almost close to the actual intake pipe pressure Pm detected by the pressure detector 19.

The experimental results shown in FIGS. 2 to 5 are based on the memory 36.
is stored as a map. With the experimental results stored in the memory 36 in this way, when the internal combustion engine 13 is actually used, if the throttle valve opening θ changes suddenly due to acceleration, as shown in FIG. 6(1), for example, Note that 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 following the intake air flow rate Q or the injection jiQ/N, as shown by the solid line in FIG. 6(3), whereas the delayed expected intake pipe pressure Pmjf changes. , changes with a time delay as shown by the broken line in FIG. 6(3). Also, in this No. 611''4(3), the actual intake pipe pressure Pm detected by the pressure detector 19
changes as shown by the two-dot chain line.

Therefore, in this embodiment, first, from the actual intake pipe pressure Pm detected by the pressure detector 19 and the rotation speed Ne per unit time of the internal combustion engine 13 detected by the crank angle detector 28, The basic injection amount TPD is determined based on the graph shown in the figure. Next, the injection ITP1 is determined from the graph shown in FIG. 2 from the expected intake pipe pressure Pmj with good responsiveness and the rotational speed Ne, and the injection 1TP2 is determined from the delayed expected intake pipe pressure Pmjf and the rotational speed Ne. injection! The difference between 1TPi and the injection amount TP2 is determined.

Subsequently, the difference obtained in this way is applied to each combustion chamber E1 to E from the throttle valve 16 of the intake pipe 15 including the surge tank 14.
The corrected injection amount T is multiplied by the intake delay correction coefficient q corresponding to the capacity of the intake path from intake pipe A1 to km of rn.
MI is determined, and this corrected injection amount TM1 is set as the basic injection amount T.
Actual fuel injection 1 by adding to PD and correcting
Find TAU. That is, TAU=TPD+η(TPI-TP2)=TPD+TM
1...(2) This provides good transient response and steady-state stability, and the air-fuel ratio is always maintained! & Can be kept at an appropriate value.

FIG. 7 shows the operation for detecting the rotation speed Ne of the internal combustion engine 13. In step s1, the crank angle detector 2
The rotation speed Ne detected by 8 is digitally converted by an analog/digital converter 33 and read into a processing circuit 34. This operation is performed by the analog/digital converter 33
This is done every time there is a conversion operation in .

No. 8 I2I represents an operation for determining the basic injection amount TPD, and is performed every time the actual intake pipe pressure P m detected by the pressure detector 19 is digitally converted by the analog/digital converter 33. In step all,
Actual intake pipe pressure P detected by one pressure detector
m is converted from analog to digital and read. In step s12, the rotation speed Ne obtained in step s1 described above is
The basic injection amount TPD corresponding to the intake pipe pressure Pm determined in step sll is read out from the memory 36 based on the map shown in FIG. 2 described above.

The ninth (2I) represents an operation for determining the expected intake pipe pressure Pmj, and is performed every time the throttle valve opening θ detected by the valve opening detector 30 is digitally converted by the analog/digital converter 33. In step s21, the throttle valve opening θ detected by the valve opening detector 30 is converted from analog to digital and read.In step s22, the throttle valve opening θ obtained in step s21 and the below-mentioned From the delayed expected intake pipe pressure Pmjf obtained in step s31, the above-mentioned figure 3 (1)
The intake air flow JiQ is read out 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 determined in step s22 and the rotational speed Ne. In step s24, the injection I determined in step s23 is
Based on Q/Ne and the rotational speed Ne, the expected intake pipe pressure Pmj is read from the map in the memory 36 based on the graph shown in FIG. 4 mentioned above.

FIG. 10 shows the operation for determining the delayed expected intake pipe pressure Pmjf, which is performed, for example, every 4 m5ec. In step s31, a constant rl is read from the map in the memory 36 based on the rotational speed Ne, based on the graph shown in FIG. P m j f + is determined.

FIG. 11 shows the operation for determining the actual fuel injection amount TAU, which is performed for each stroke of the internal combustion engine 13, for example.

In step s41, based on the predicted intake pipe pressure Pmj obtained in step S24 and the rotational speed Ne obtained in step s1, the injection jl14 amount TP1 is calculated from a map in the memory 36 based on the graph shown in FIG. is read out. In step s42, the injection amount TP2 is read from the map in the memory 36 based on the delayed expected intake pipe pressure Pmj f obtained in step s32, the rotational speed Ne, etc., based on FIG. In step s43.

Injection amount TP1 obtained in step s41 and step s
The actual fuel injection amount TAU is calculated from the injection amount TP2 obtained in step 42 based on the second equation.

In this way, in this embodiment, the basic injection amount T
Since PD is corrected, as shown in FIG. 6 (3), in steady state, the delayed expected intake pipe pressure Pmj
f and the expected intake pipe pressure P rn j coincide with each other, but...
The injection amounts TP1, TP2 determined using the equations TP1 and TP2 match during steady state. Therefore, even if the intake air flow rate Q is not strictly measured, it is possible to obtain good stability in steady state, and it is also possible to obtain good stability even when the atmospheric pressure changes significantly. can. Therefore, the accuracy of the valve opening degree detector 30 does not need to be very high, and the installation of the valve opening degree detector 30 can absorb errors and the like and keep the air-fuel ratio constant at all times.

In the embodiment described above, the corrected injection amount TM1 is the injection amount TP1. Although determined using TP2, in another embodiment of the present invention, the expected intake pipe pressure PmJ,
It may be determined using Pmj f, i.e. TAU=TPD+y7*(Pmj-Pmjf)
---(3) However, K is the intake pipe pressure Pmj, P
There is an arithmetic formula ta for determining the injection amount from mjf, and it may be a constant value or a value that changes depending on the rotational speed Ne.

[Correction injection] lTM1 may be obtained based on the intake air flow rate Q, and in this case, the injection amount Q/N
When e is QN, the delayed injection amount QNf is QNf,=Q
Nfl-1+ −(QNI-QNfl-1> ・
... can be obtained from (4), and this delayed injection amount QN
The actual fuel injection jiTAU may be determined from f and the injection amount QN as shown by the following formula.

TAU=TPD+η(QN-QNf)=TPD+TM1
...(5) As shown in FIG. 3 (2), the delayed injection -IQNf becomes larger as the intake air flow -1iQ becomes larger and as the throttle valve opening θ becomes larger. .

FIG. 12 is a sectional view of a 14-ft surge tank for explaining the concept of another embodiment of the present invention.

The intake air via the throttle valve 16 is
As shown in Figure 2 (1), the inside of the surge tank 14 is filled with high-density air and then flows out into each of the intake pipes A1 to Arn. On the other hand, during 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 each intake pipe A1 to Am. do. Therefore, in this example,
Considering the influence of the surge tank 14 and the intake path from the downstream side of the throttle valve 16 of the intake pipe 15 to each intake pipe A1 to Arn, the actual fuel f4rfn injection amount T
AU is determined as follows.

That is, injection 11Q/Ne is obtained by dividing the intake air flow rate Q shown in FIG. 3 (3) by the rotational speed Ne from the state quantity TP2 and the throttle valve opening θ obtained as described below. Let the state quantity TPI be the state quantity TP2, and the state quantity TP2 be TP2. =TP2. ．． + -(TPI-TP21.□I
)...(6), and set the constant W to, for example, 30~
By choosing an appropriate value of around 40, this condition IT
As shown by the broken line in FIG. 6(3), P2 can be made to have a change close to the actual intake pipe pressure Pm shown by the two-dot chain line in FIG. 6(3). This situation! 9ffiTP2 is updated, for example, every 4 to 5 m5ec sampling operation.

Further, correction of the angle of the intake path including the surge tank 14 is performed as follows. When the throttle valve opening degree θ changes due to acceleration as shown in FIG. 13(1), the intake pipe pressure Pm changes as shown in FIG. 13(2), thereby causing states JiTP1, TP2 change as shown by solid lines and broken lines in FIG. 13(3), respectively. This figure 13 shows that the atmospheric pressure is 76
Represents changes at relatively low altitudes around 0 mm Hg.

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

These figures 13 and 141? As is clear from J, the time rate of change ΔPm of the intake pipe pressure Pm is smaller at high altitudes, whereas the state quantity TP1. ．． TP2 changes almost the same even in highlands as in lowlands.6 Therefore, if correction is made using the corrected injection amount TMI, excessive correction will be made in highlands where air density is low.

For this reason, the capacity of the intake path is set to V, and the correction injection amount TM2 is calculated using the amount of change ΔTP2 per unit time in this capacity (■).
Seeking the above letter! Correct the basic injection MTPD along with the corrected injection amount TMI obtained from JITP1 and TP2,
Find the actual fuel injection amount TAU.

TAU=TPD η*K (TPI-TP2)-V*Δ
TP2=TpD+TM1-7M2 ・
(7) FIG. 15 shows the operation for determining the corrected injection amount TMI, which is performed every time the throttle valve opening θ detected by the valve opening detector 30 is converted from analog to digital. In step u21, the valve opening degree detector 30
The throttle valve opening degree θ detected by is converted from analog to digital and read. In step u22, the intake air flow rate Q indicated by the third eJ(3) is read from the memory 36 from the throttle valve opening θ obtained in step u21 and the state 1jlTP2 obtained as described later. In step u23, the intake air flow rate Q obtained in step u22 is divided by the rotation vLN e obtained in step S1 to obtain the state quantity TPI. In step u24, the difference between the state fiJJITP1 obtained in step u23 and the state quantity T P2 obtained as described below, the suction efficiency η, and the injection amount conversion coefficient are calculated as shown in the following formula. A corrected injection jtTM1 is determined.

TMI-η*to* (TPI-TP2)
(8) FIG. 16 shows the operation for determining the shape R amount TP2, which is performed, for example, every 4 m5ec. In step u31, the state g obtained in step u23 is
, based on the sixth equation using the quantity TPI! ! ! iT
P2 is required.

FIG. 17 shows the operation for determining the corrected injection amount TM2, which is performed, for example, every 20 m5ec.

In step u41, the current sampling state fiJ
The difference between iTP2 and the state quantity kTP2° at the previous sampling time before 20m5ec, that is, the unit time 20m5
The amount of change ΔTP2 in the state quantity TP2 per ec is determined, and in step u42, the amount of change ΔTP2 determined in step II41 and the volume iV of the intake path are calculated to determine the corrected injection amount TM2.

FIG. 18 shows the operation for determining the actual fuel injection amount TAU, which is performed, for example, every stroke of the internal combustion TA engine 13. In step u51, the basic injection amount TPD obtained in step s12 is corrected by the corrected injection amount TMI obtained in step u24 and the corrected injection 117M2 obtained in step u42, and actual fuel injection is performed. The quantity TAU is determined. In this way, the response delay due to the intake path including the surge tank 14 is taken into account, and the fuel injection amount TAU can be determined in which changes in intake air due to changes in atmospheric pressure are taken into account.

In each of the above-mentioned embodiments, it was assumed that the combustion air flowing into each of the intake pipes A1 to Am was supplied only through the throttle valve 16, but in reality, the combustion air is Then, the processing device 31 conducts/cuts off the flow rate control valve 24 provided in the side passage 23, and the EGR is performed. Therefore, even if the throttle valve opening degree θ is the same, the state quantity T shown in FIG. 19 is stored in the memory 36.
A map of the intake air flow rate Q corresponding to P2 is stored, and in this FIG. 19, the solid line 11 indicates the flow rate control valve 24.
The broken line 12 represents the change in the intake air flow rate Q1 when the EGR is closed and the EGR is OFF, that is, the fresh air intake flow rate Q1 via the throttle valve 16.
The intake air flow rate in the case of N, that is, the fresh air intake flow rate Q・
The actual The fuel injection amount IT AU can be maintained at an accurate value corresponding to the fresh air intake flow rate Q1.

However, the map value reading operation as described above is immediately switched at the EGR (7) ON10FF times tl and t2 shown in FIG. 20 (1), and therefore the basic injection amount TPD is ), and immediately after time t1 when EGR changes from OFF to ON, the exhaust gas recirculation J! Since lQ2 is small, the air-fuel ratio is in a lean state, and on the other hand, at time L2 when EGR changes from ON to OFF, the exhaust gas recirculation amount Q2 does not immediately become zero, so the air-fuel ratio is in a rich state. Become.

Intake pipe pressure P during 0N10FF operation of EGR like this
m changes as shown in Fig. 20 (3). Therefore, when switching the ON10 FF state of EGR, it is desirable to perform transient correction as shown by the broken line in Fig. 20 (2). In this embodiment, transient correction is performed as follows.

That is, first, the state quantity TPI obtained by dividing the intake airflow fiQ obtained as described above and the rotational speed Ne is obtained, and then the state JITP2 is obtained as shown by the above-mentioned formula 6. . The state quantity TP1 obtained in this way. In TP2, the throttle valve opening θ is the 21st
When it changes as shown in Figure (1), it changes as shown by the solid line and broken line in Figure (2), respectively.

As is clear from this FIG. 21 (2), the state quantity TPI
follows the change in the throttle valve opening θ, and the state quantity TP2 shows a stable change that approximates the state quantity TPI, and these two states @! JTP 1. The actual fuel injection amount TAU is determined from TP2 as shown by the second equation described above.

However, in this case, the basic injection I read out from the memory 36
The map values of LTPD are different when EGR is OFF, shown by the solid line in FIG. 2.2, and when EGR is ON, shown by the broken line in FIG. , for example, when E and GR are OFF, the basic injection amount TPD is made larger than when EGR is ON.

Therefore, when EGR is turned from OFF to ON at time t1 as shown in FIG. 23(1), the basic injection amount TPD changes as shown in FIG. 23(3), and its trajectory is as shown in FIG. As shown, from the relatively large injection amount value P1 when EGR is OFF, the same intake pipe pressure P
EGR ON at the same rotation speed Nel as m, 1
After passing through a value P2, which is a relatively small injection amount at a normal time, the steady state value P3 is reached as the intake pipe pressure Pm increases as shown in FIG. 23(2). The change in the intake air flow rate Q at this time is the EGR O
From the value at FF, state Fl! With JiTP2 unchanged, it rises to the value indicated by reference mark P2a, and reaches reference mark P3a.
The steady state value shown by is reached. State quantity TP at this time
Changes in 1 and TP2 are shown by solid lines and broken lines, respectively, in FIG. 23 (4).

Furthermore, when EGR changes from ON to OFF at time t2 as shown in FIG. 26(1), the basic injection ITPD changes as shown in FIG. 26(3), and its trajectory is shown in FIG. From the relatively low value at the time of EGR OFF indicated by reference mark P4, the same intake pipe pressure Pml
and the value P5 when EGR is OFF at the rotation speed Ne1
As the intake pipe pressure Pm decreases as shown in FIG. 26(2), it reaches the steady state value indicated by reference numeral P6 in FIG. 27. Also, at this time, the change in the intake air flow rate Q is determined by turning on the EGR indicated by reference mark P4a in FIG.
From the relatively high value at
Reach 6a.

The changes in the state quantities TP1 and TP2 at this time are shown in Figure 26 (4
) are shown by solid lines and broken lines, respectively.

As is clear from FIGS. 23 and 26, at time t1 when EGR changes from OFF to ON, the basic injection amount TPD decreases, whereas the state amount T
PI increases. 7', At time t2 when EGR changes from ON to OFF, the basic injection amount TPD increases, and in contrast, the state filLTP1 decreases.

FIG. 29 shows the operation for determining the basic injection amount TPD, which is performed every time the intake pipe pressure Pm detected by the pressure detector 19 is digitally converted by the analog/digital converter 33. In step r1.1, the actual intake pipe pressure Pm detected by the pressure detector 19 is converted from analog to digital and read. step r
12, whether EGR is ON or not, that is, flow control valve 2
4 is open, and if so, in step r13, the rotational speed Ne obtained in step s1 and the intake pipe pressure Pm obtained in step rll are determined.
From this, the basic injection amount TPD is read out from the memory 36 based on the map shown by the broken line in FIG.

When EGR is OFF in step r12, the basic injection amount TPD is read out from the memory 36 in step r14 based on the map shown by the solid line in FIG.

FIG. 30 shows the operation for determining the corrected injection amount TMI, which is performed every time the throttle valve opening θ detected by the valve opening detector 30 is converted from analog to digital. In step r21, the throttle valve opening θ detected by the valve opening detector 30 is converted from analog to digital and read. In step r22, it is determined whether EGR is ON, and if so, the process moves to step r23, where the throttle valve opening degree θ obtained in step r21 and the shape R amount T obtained in step u31 are determined.
P2 to EG indicated by the broken line in FIG.
The map value of the intake air flow rate Q when R is ON is read out from the memory 36, and the process moves to step r24. When EGR is OFF in step r22, steps r2 and 5
Then, in step 190, the map value of the intake air flow rate Q when EGR is OFF is read out from the memory 36, and the process moves to step r24. In step r24, step r23. The state quantity TPI is calculated from the intake air flow rate Q read in r25 and the rotational speed Ne obtained in step s1, and in step r26, the state quantity TP1 obtained in step r24 and the rotation speed Ne obtained in step s1 are calculated.
Condition required at 31! Ql! 1TP2, the intake efficiency η, and the injection amount conversion coefficient, the corrected injection amount TM1 is determined based on the eighth equation.

FIG. 31 shows the operation for determining the actual fuel injection amount TAU, which is performed for each stroke of the internal combustion engine 13, for example.

In step r51, the step r13 or r14
The actual fuel injection amount TAU is determined based on the second equation from the basic injection amount TPD read out and the corrected injection amount TM1 determined in step r26.

In this way, even during the transition period when EGR is ON10FF, the basic injection amount TPD is set to the state amount TPI.

By correcting the corrected injection amount TM1 determined based on TP2, that is, by determining the actual fuel injection amount TAU based on the second equation, the fuel injection amount TAU optimal for the change in the fresh air intake flow rate Q1 is determined. can be calculated, and the air-fuel ratio can always be kept stable.

Effects of the Invention As described above, according to the present invention, the basic injection amount TPD is first determined from the rotational speed Ne per unit time of the internal combustion engine and the actual intake pipe pressure Pm, and then the state related to the intake air flow rate Q is calculated. R
Find the state quantity TPI, find the state quantity TP2 that changes to follow this state quantity TPI with a time delay, and then calculate the state quantity TPI.
The corrected injection amount TMI is determined based on the difference between A good fuel injection amount TAU can be obtained.

Furthermore, since the state quantity TP2 is corrected so as to approach the state quantity TPI during steady state, stability during steady state can be further improved.

Furthermore, since the intake air flow rate Q is determined from the throttle valve opening θ and the state quantity TP2, the intake air flow rate Q thus determined is the fresh air intake flow rate Q1 via the throttle valve and the exhaust gas recirculation amount. Q2 corresponds to the total intake flow rate, and therefore, by using the state quantity TP2 in this way, the EGR ON10
Fluctuations in the air-fuel ratio can be suppressed even during transient FF operation.

According to the present invention, first, basic injection is performed based on the rotational speed Ne per unit time of the internal combustion engine and the actual intake pipe pressure Pm! T.P.
Find D, and then calculate the state fiJiT related to the intake air flow rate Q.
P1 is determined, a state quantity TP2 that changes to follow this state quantity TPI with a time delay is determined, and then a corrected injection amount TMI is determined based on the difference between state JiTP1 and state quantity TP2, and the above-mentioned state fiJiTP2 and surge Calculate the corrected injection amount TM2 in relation to the capacity of the intake path including the tank, etc.
The basic injection, 1TPD, is changed to the corrected injection amount TM1. T
Since the actual fuel injection amount TAU is determined by correcting with M2, the actual fuel injection amount TAU is determined that has good steady-state stability and transient response, and also takes into account intake delay due to the intake path. be able to.

In this way, when the throttle valve opening changes or when the EGR reaches 0.
It has good responsiveness during transients such as N10FF operation,
In addition, the air-fuel ratio can always be kept at the optimum value with good stability during steady state.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of the present invention, and FIG. 2 is an intake pipe pressure Pm, Pm at each rotation speed Ne of the internal combustion engine 13.
Fig. 3 is a graph showing the relationship between the injection amounts TPD, TPi, and TP2 and the delayed expected intake pipe pressure Pmjf, the delayed injection amount QNf, or the state quantity TP2 and the intake air flow rate Q at each throttle valve opening θ. A graph showing the relationship between
FIG. 4 is a graph showing the relationship between the injection amount Q/N e and the expected intake pipe pressure Pmj at each rotation speed Ne, and FIG. 5 is a graph showing the change in the constant n with respect to the change in the rotation speed Ne.
FIG. 6 is a waveform diagram for explaining the operation of an embodiment of the present invention, FIGS. 7 to 11 are flowcharts for explaining the operation of an embodiment of the present invention, and FIG. A sectional view of the surge tank 14 showing the flow of intake air for explaining the operation of another embodiment, FIGS. 13 and 14 are waveform diagrams for explaining the operation of another embodiment of the present invention, 1st
5 to 18 are flowcharts for explaining the operation of other embodiments of the present invention shown in FIGS. 12 to 14,
FIG. 19 is a graph showing changes in the intake air flow rate Q when EGR is 0N10FF to explain the principle of yet another embodiment of the present invention, and FIGS. 20 and 21 are graphs showing the embodiment shown in FIG. 19. A timing chart for explaining the operation of the example, FIG. 22 is a graph showing the relationship between intake pipe pressure Pm and basic injection fTPD when EGR is ON and OFF, and FIG. 23 is a graph showing the relationship between FIG. A waveform diagram for explaining the operation shown in Fig. 21, Fig. 24 is a graph showing the locus of the basic injection amount TPD during the operation shown in Fig. 23, and Fig. 25 is a graph showing the trajectory of the basic injection amount TPD during the operation shown in Fig. 23. A graph showing the locus of the intake air flow rate Q during operation, Fig. 26 is a graph showing the trajectory of the intake air flow Q during operation.
Waveform diagrams for explaining other operations shown in FIG. 0 and FIG. 21, and FIG. 2'7 show the basic injection J! during the operation shown in FIG. 26. Graph showing the trajectory of 1TPD, No. 28
The figure shows the intake air flow rate Q during the operation shown in Figure 26.
Graphs showing the trajectory of, Figures 29 to 31 are Figures 19 to 31.
29 is a flowchart for explaining the operation of the further embodiment of the present invention shown in FIG. 28. 13... Internal combustion engine, 14... Surge tank, 15.
...Intake pipe, 16...Throttle valve, 19...Pressure detector, 27.38...Temperature detector, 20...Exhaust pipe, 23...Side passage, 24...Flow rate control Valve, 28...
・Crank angle detector, 30...Valve opening detector, 31・
...Processing device, 36...Memory, A1-Am...Intake pipe line, B1-B m...Fuel injection valve, E1-Em...
... Combustion chamber, 01~0m...Spark plug agent Patent attorney Kei Saikyo Figure 7 Figure 8 Figure 9 @ Figure 10 Figure 11 A to Lff Expected intake pipe pressure 71 Pmj f Figure 2 Intake pipe pressure Pm, Pmj, Pmjf Figure 3 Figure 15 Figure 16 Figure 17 Figure 18 A to B-Hori Figure 19 1 State quantity TP2 Figure 20 Figure 22 Figure Intake pipe pressure Pm Figure 4 Go to other processing Figure 31 A to 2σ fu 23 engineering

Claims (5)

[Claims] (1) Determine the basic injection amount TPD from the rotation speed Ne per unit time of the internal combustion engine and the actual intake pipe pressure Pm, determine the state quantity TP1 related to the intake air flow rate Q of the internal combustion engine, and apply the state quantity TP1 to the state quantity TP1. Find the state quantity TP2 that follows and changes so that they match or almost match with a time delay, find the corrected injection quantity TM1 based on the difference between the state quantity TP1 and the state quantity TP2, and correct it with the basic injection quantity TPD. A fuel injection amount control method for an internal combustion engine, characterized in that an actual fuel injection amount TAU is determined from an injection amount TM1. (2) The intake air flow rate Q is determined from the opening degree θ of a throttle valve that supplies combustion air to the internal combustion engine and the state quantity TP2. Fuel injection amount control method. (3) The state quantity TP2 is equal to the state quantity TP1 when the state quantity TP2 is the injection amount determined from the delayed expected intake pipe pressure Pmjf and the state quantity TP1 is the injection amount determined from the expected intake pipe pressure Pmj. 2. A fuel injection amount control method for an internal combustion engine according to claim 1, wherein the fuel injection amount control method for an internal combustion engine is corrected so that the amount approaches the amount. (4) The intake air flow rate Q is determined from the throttle valve opening θ and the state quantity TP2, and is the total intake flow rate of the sum of the fresh air intake flow rate Q1 via the throttle valve and the exhaust gas recirculation amount Q2. A fuel injection amount control method for an internal combustion engine according to claim 1, characterized in that: (5) Determine the basic injection amount TPD from the rotation speed Ne per unit time of the internal combustion engine and the actual intake pipe pressure Pm, determine the state quantity TP1 related to the intake air flow rate Q of the internal combustion engine, and apply the state quantity TP1 to the state quantity TP1. Find the state quantity TP2 that follows and changes so that they match or almost match with a time delay, find the corrected injection quantity TM1 based on the difference between the state quantity TP1 and the state quantity TP2, and compare the state quantity TP2 and the surge tank. A fuel for an internal combustion engine, characterized in that a corrected injection amount TM2 is determined in relation to the capacity of an intake path including the amount, and an actual fuel injection amount TAU is determined from the basic injection amount TPD and the corrected injection amounts TM1 and TM2. Injection amount control method.