JPS62265449A - Engine controller - Google Patents

Abstract

PURPOSE:To enable a more highly precise control by estimating an air quantity actually sucked by an engine through estimating a suction pipe internal pressure on the basis of a throttle opening and an engine revolution-number and according to a predetermined equivalent model, and figuring out a fuel injection quantity and an ignition timing. CONSTITUTION:At a thing wherein an injector 5 is driven and controlled by a control unit 20 according to the operating condition of an engine 1, the control unit 20 is made to memorize the dynamic characteristic of an air suction system which is transformed to an equivalent model. And a suction pipe pressure is always estimated from steady state to transient state by making use of this equivalent model and on the basis of a throttle opening and the revolution- number of the engine, and an air quantity which is to be filled into a chamber 3 at the lower stream of a throttle valve 4 and the capacity C of a suction pipe at a transient time is estimated through this estimated pressure. And form this filled-in air quantity estimate value and an instrumentation-intake-air quantity, the air quantity to be actually sucked in is estimated, and a fuel injection quantity and an ignition timing are decided on the basis of this air quantity and the engine revolution-number.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field 1) The present invention is directed to a fuel injection engine that has a chamber or surge tank downstream of a throttle valve in the intake system and is equipped with a thermal and linear air flow meter. The present invention relates to an engine control device that controls fuel injection amount and ignition timing based on fuel injection amount and engine rotation speed.

(Prior art 1) Recently, fuel injection devices using air flow meters have been widely used in automobile engines. The intake air flow rate Qa is accurately detected, and the fuel amount Ti, that is, the fuel ll! injection pulse width Tp, is set as the engine rotational speed Ne so that the amount of fuel corresponding to the air flow indication Qa, for example, the stoichiometric air-fuel ratio, is achieved. Tp=Qa
/Ne, etc., and by driving the injector by the injection pulse width Tp, fuel is supplied to the engine with extremely high accuracy. In addition, when controlling the ignition timing as well, the injection pulse width Tp is used to calculate the ignition timing.
is often used as data for load determination. Therefore, measurement of intake air IQa requires extremely high accuracy.

Furthermore, recently, there has been a trend toward the use of hot wire type air flow meters and the like, which have high responsiveness as sensors, as air flow meters. However, the air flow meter is only located upstream of the throat valve, and does not directly measure the amount of air being sucked into the engine.

For example, when the throttle valve is changed from closed to open, the amount of air flowing into the engine increases and at the same time the pressure in the chamber downstream of the throttle valve and the suction pipe also increases, so the amount of air required to increase this pressure also increases. It will be measured with an air flow meter. In other words, the air flow meter on the upstream side of the throttle valve measures an amount of air that is greater than the amount of air flowing into the engine when the throttle valve is opened to open, albeit for a moment. This appears as a spike-like overshoot in the air flow rate, which increases as the volume of the chamber downstream of the throttle valve and the intake manifold increases, and also increases with responsive sensors such as hot wire air flow meters. .

On the other hand, in MPI (multipoint injection), the injector (fuel injection valve) is located downstream of the intake manifold, so if the fuel is injected according to the measured air, the air flowing into the engine will contain more than necessary. of fuel is supplied, the air-fuel ratio A/F suddenly becomes richer, and CO and HC in the exhaust gas are added. Moreover, in severe cases, overrichness causes problems such as a reduction in engine output and a worsening of driving feeling.

Furthermore, in the case of an engine control device that controls the ignition timing as well, the ignition timing may be momentarily retarded, resulting in a decrease in engine output and worsening of emissions.

Note that the air-fuel ratio A similarly changes when the throttle valve opens → closes.
/F and ignition timing may deviate from their optimum values.

For this reason, for example, as shown in Japanese Patent No. 57-73831, the movement of the throttle valve is detected and the flow rate is measured based on the output of a hot wire type air flow meter. By correcting the ftjm fuel injection pulse width Tp, it is possible to eliminate the problem that the appropriate air-fuel ratio changes due to a sudden change in the opening and cause the engine to malfunction.It also improves responsiveness during acceleration and reduces the This was done to prevent misfires and rattling phenomena.

Moreover, what is shown in Machima 59-170428 publication is a basic fuel injection 9A suspension system that discharges intake air @ and engine speed based on the amount of change in signal voltage from a hot wire type air flow meter over time. In this way, the same effect as the conventional example described above is obtained.

[Problem to be Solved by the Invention 1] Conventionally, problems caused by changes in the appropriate air bearing ratio due to sudden changes in the opening of the throttle valve have been solved by using the thrower j.
Although corrections were made based on changes in the signal voltage from the wire-type air flow meter over time, errors in detecting the amount of intake air into the engine that occur during transients could be corrected indirectly. Since the system was configured to make corrections by estimating the air-fuel ratio, it was not possible to accurately follow changes in the state of the intake system, and although a certain correction effect was obtained, it was difficult to maintain the air-fuel ratio at an appropriate value. The problem is that it is not possible.

This invention was made in order to solve the above-mentioned problems of the conventional example, and is caused by the total error in the intake air range caused by the contours of the chamber downstream of the throttle valve and the intake manifold that occur when the throttle valve is suddenly opened and closed. An object of the present invention is to provide an engine control device that can more accurately measure the intake air amount and maintain the optimum fuel injection amount and ignition timing.

[Means for Solving the Problems 1] In order to achieve the above object, the present invention provides an air flow meter upstream of the thrower I valve, an injector downstream of the intake pipe, and a thrower I valve opening sensor. In an engine, the vJ characteristics of the engine intake system are determined by the throttle valve downstream pressure Pc and the throttle valve downstream pressure Pc and the throttle valve downstream R1 as a function determined by the throttle opening, and the engine resistance R2 as a function of the engine rotation speed. The volumes ff1c of the downstream chamber and the intake pipe are stored in memory in advance as constants and modeled equivalently, and this equivalent model is used to calculate the throttle opening detected by the throttle opening sensor and the engine rotation. The intake pipe internal pressure is always estimated from the steady state to the transient state by the number, and from this estimated intake pipe pressure, the amount of air filled in the chamber downstream of the throttle valve and the capacity C of the intake pipe during the transient state is estimated. Then, calculate the estimated amount of charged air and the amount of intake air measured by the air flow meter, and calculate the amount of fuel based on this estimated value of the actual engine intake air port and the engine speed. ) The suspension and ignition timing are determined.

[Function] The engine control device according to the present invention grasps the dynamic characteristics of the air in the intake pipe, and controls the IP by replacing it with an electric circuit.
The pressure inside the intake pipe is stored in the memory within the device, and the pressure inside the intake pipe is constantly estimated based on the throttle opening and engine speed, and the air is filled into the chamber downstream of the throttle valve and into the intake pipe during transients such as when the throttle is closed. The amount is determined from the fluctuation rate of the estimated intake pipe internal pressure and the 8 values in the chamber downstream of the throttle valve and in the intake pipe.

Then, the estimated amount of charged air is added to or subtracted from the amount of intake air measured by the air flow meter to estimate the amount of air actually taken into the engine. Based on this, the basic fuel injection amount is calculated, and the optimal ignition timing is determined through a map search, etc.

[Actual box Example 1 Figures 1 to 7 are diagrams showing an embodiment of the present invention. Figure 1 is a system diagram of the engine control WJia, and Figure 2 is a model of the engine intake system and replaced with an electric circuit. 3 is a block diagram showing the configuration of the processing means of the engine control device, FIG. 4 is a diagram showing the setting of the throttle resistance R1 with respect to the throttle opening, and FIG. 5 is a model diagram showing the configuration of the processing means of the engine control device. FIG. 6 is a flowchart showing the operation, and FIG. 7 is a transient response diagram showing changes in each data during transition.

In Fig. 1, 1 is the engine, 2 is the intake pipe including the manifold, 3 is the chamber downstream of the throttle valve, 4 is the throttle valve, 5 is the injector (fuel injection valve), 6 is the ignition coil, and 10 is the hot wire type. 11 is a throttle opening sensor, 12 is a water temperature sensor, 13 is a crank angle sensor, 14 is an oxygen sensor,
20 is an engine control i1 consisting of a microcomputer.
1 device.

In such a system, the engine control device 20 in J3 controls the intake air f measured by the air flow meter 1o.
The basic fuel n is determined based on f1Qa and the engine rotation HN e determined by the signal from the crank angle sensor 13.
The injection height T1, that is, the injection pulse width Tp, is set to Tp=-
The injection pulse width is outputted in the form of Qa /Ne, and corrections are made based on the wetness of the cooling water detected by the water temperature sensor 12, and feedback correction is performed based on the output from the oxygen sensor 14 to inject the injector 5 with the corrected injection pulse width Tp. For example, the stoichiometric air-fuel ratio A/corresponding to the intake air, 9Qa.
Inject the amount of fuel that will result in F. Further, the optimal ignition timing corresponding to the measured intake air ff1Qa and engine speed tqe is determined by map search or the like, and ignition is performed via the ignition coil 6.

In this control system, during a transient period due to the opening and closing of the throat valve 11, a spike-like overshoot occurs in the measured intake air amount Qa due to the mustard C in the chamber 3 downstream of the throat valve 1 to the intake pipe 2. !・Or undershoe 1~ occurs, so the air flow meter 10 measures a field different from the air amount Qe actually taken into the engine 1. In order to perform this correction, the engine control device 20 has a second A model of the dynamic characteristics of the intake system as shown in the figure is stored.The model of the intake system shown in Figure 2 (■) uses the air flow meter 10 to The measured intake air ff1Qa is set to the current value ■, the flow path resistance of the throttle 1 to 2 parts according to the opening degree of the throttle valve 4 is set to the variable resistor R1, and the engine part resistance corresponding to the engine speed is set to the variable resistor R2. , the volume of the chamber 3 downstream of the throttle valve and the intake pipe 2 is the capacitor volume C, the amount of air Qc filling the volume of the chamber 3 and the intake pipe 2 downstream of the throttle valve 1 to the throttle valve during a transient period is the current value Jc, and the engine By replacing the intake air ff1Qe flowing into the intake pipe 1 with a current value 1e, and replacing the internal pressure P of the intake pipe 2 with a voltage V, an equivalent model as shown in FIG. 2(c) is approximated.

In this equivalent model, the transient response of the voltage V after the variable resistor R1 with respect to the stepwise input of the input voltage Vo is expressed as V=Vo (Rt/(R1+R2)). Here, the throttle part resistance R1 is an approximate value expressed as (Ps-P)/Qa according to the throttle opening θ.
The values are as shown in FIG. 4, and are stored in the memory in a table with the throttle opening degree θ as a grid. Further, the engine resistance R2 is the engine rotation speed N+31. :P depending
/Qe, which is a value as shown in FIG. 5, and is stored in the memory in a table with the engine rotational speed Ne as a lattice.

In this way, the voltage V, that is, the intake pipe pressure P, is determined by the time constant τ
Since it can be approximated as a first-order lag system of -C-Rt -R/ (Rt +R2), the engine resistance R2 can be expressed as the throttle resistance R1 as a function determined by the throttle opening θ.
is stored in memory as a function of the engine rotational speed Ne, and the suction side pressure Pa and the volume ff1c in the chamber 3 and intake pipe 2 downstream of the throttle valve are stored as constants. If the next delay processing means is provided, the intake pipe internal pressure P can be estimated.

By calculating the time differential of this pressure P, the amount of filling air Qc in the chamber 3 and the intake pipe 2 downstream of the throttle valve during a transient period can be calculated by C-dp/dt, and the actual intake air amount of the engine 1 can be calculated by C-dp/dt. Air mQe is determined by Qa-Qc, and it becomes possible to accurately determine the fuel injection amount and ignition timing without being affected by overshoot or undershoe 1- of the measured intake air amount Qa that occurs during a transient period.

The above arithmetic processing is performed by various means built into the engine control device 20, as shown in FIG. In the figure, reference numeral 21 is an engine rotation speed calculation means, which calculates the engine rotation speed Ne based on the signal from the crank angle sensor 13.
seek. Reference numeral 22 denotes a measured intake air amount calculation means, which converts the voltage signal from the hot wire type air flow meter 10 into intake air ff1Qa. 23 is the throttle part resistance R
1 is a throttle resistance table storing the throttle opening degree θ as a lattice, 24 is an engine resistance table storing the engine resistance R2 and the engine rotation speed Ne as a lattice, and 25 is a chamber 3 downstream of the throttle valve. Capacity ΦC of intake pipe 2 and intake side pressure? a (approximately atmospheric pressure); 26 is a throttle section resistance calculation means; 27 is an engine section resistance calculation means; 28 is an intake system time constant Toda means; 29 is an intake pipe internal pressure ps to be maintained in a steady state. 30 is a first-order lag processing means for performing first-order lag processing on the intake pipe internal pressure Pa to obtain a transitional intake pipe internal pressure P (shi); 31 is a filling sudden air ω calculation means; 32 is an actual engine intake air suspension means; 3
Reference numeral 3 represents a fuel injection detection means, and 34 represents an ignition timing calculation means.

Next, the operation of the engine fhlla device 20 constructed as described above will be explained with reference to the flow chart shown in FIG. 6 and the transient response diagram shown in FIG. 7.

In step 310, the engine 1i11 control device 20 converts the voltage signal from the air flow meter 10 into a total intake air flow rate Qa' in the measured intake air amount calculation means 22.
1) The throttle valve 4 is stepped, for example, as shown in FIG. 7(a).
), a signal Qa with a spike-like overshoot as shown in FIG. 7 is output. Then, input the throttle angle θ from the throttle opening sensor 11 and the engine rotation speed N+3 from the engine rotation speed calculation means 21 (Step 5102 ), and the throttle resistance output means 26 use the throttle opening θ as an address signal. The throttle section resistance R1 preset from the throttle section resistance table 23 is read out, and the engine section resistance calculation means 27 reads out the engine section resistance preset from the engine section resistance table 24 using the engine rotation speed signal Ne as an address signal. Read R2 (step 5103).

Next, the intake system time constant calculation means 28 calculates the first-order lag time constant τ of the intake system using the read throttle resistance R1, engine resistance R2, and variable ff1c stored in the memory 25 (step 5104). Further, the intake pipe pressure calculating means 29 calculates the intake pipe pressure P8 in the steady state by using the resistances R1 and R2 and the intake pressure PO stored in the memory 25 (Step 5105), and calculates the intake pipe pressure ps. In the first-order delay processing means 30, first-order delay processing using a time constant τ is performed every calculation period Δ, and the intake pipe internal pressure P(t) at the time of transition is obtained (
Step 8106), the intake pipe internal pressure P is estimated as shown in FIG. Next, the filling air amount calculating means 31 calculates the filling air ff1QC to be filled in the chamber 3 downstream of the throttle valve and the intake pipe 2 during a transient period, based on the time differential value of the estimated intake pipe internal pressure P and the capacity C (step 310
7), estimated as shown in Fig. m7 (e).

Based on this estimated air ♀Qc and the measured intake air ff1Qa obtained by the measured intake air maximum calculation means 22, the actual engine intake air mass calculation means 32 calculates the air fAQo actually taken into the engine 1 (step 8108). ,
The actual engine intake air UQO is estimated as shown in Figure 7 (0).The actual engine intake air UQO obtained in this way is
There is no longer a spike-like overshoot like the measured intake air ff1Qa, and based on this and the engine speed NO, the fuel injection amount calculation means 33 calculates Tp = K''QO/N.
Punishment in the form of c; injection suspension Ti, i.e. injection pulse @Tp
is calculated (step $109), and 0 in Figure 7 is calculated even during the transient period.
The air-fuel ratio A/F as shown in FIG.
Large fluctuations in the air-fuel ratio A/F as shown in Figure G) do not occur.

In addition, the ignition timing calculation means 34 also calculates the actual engine intake air ff1Qo corresponding to the actual load and the engine rotation speed NO.
Since the optimum ignition timing is determined by map search or the like based on the above (step 8110), unnecessary retardation does not occur during transition.

Although the above embodiment describes the transient state in which the throttle valve is suddenly closed, the same operation is performed also in the transient state in which the throttle valve is suddenly closed. It is possible to prevent inconveniences caused by deviations from the optimum values.

[Effect of the Invention 1] As is clear from the above description, the engine control device of the present invention estimates the intake pipe internal pressure by taking into account the zero capacity of the chamber downstream of the throttle valve and the intake pipe, and further estimates the intake pipe internal pressure by considering the chamber downstream of the throttle valve and the intake pipe. Since we estimated the amount of air inhaled by
Even during transient times such as when opening and closing the throttle valve, it eliminates the effects of overshoot and undershoot of the measured intake air port caused by the capacity of these valves, minimizes the deviation from the set value of the air-fuel ratio, and reduces exhaust gas. It is possible to prevent the generation of CO and HC inside.

Furthermore, it is possible to stabilize the output and improve the driving feeling. In general, it is possible to minimize the deviation of the ignition timing from the appropriate value, which has the effect of improving driving feeling and emissions.

[Brief explanation of drawings]

Figures 1 to 7 are diagrams showing one embodiment of the present invention, Figure 1 is a system diagram of the engine ill III device, and Figure 2 is a model (a) of the engine intake system replaced with an electric circuit. Model diagram showing equivalent model (6), 3rd
The figure is a block diagram showing the combination of the processing means of the engine control gA device, Figure 4 is a diagram showing the setting of the suit 1~le part resistance R+ with respect to the throttle opening degree, and Figure 5 is the engine part vs. engine speed. It is a response diagram of resistance R2. DESCRIPTION OF SYMBOLS 1... Engine, 2... Intake pipe, 3... Chamber downstream of throttle valve, 4... Throttle valve, 5...
Injector, 10...Air flow meter, 11...
- Throttle opening sensor, 13... Crank angle sensor, 20... Engine control device, 23... Throttle section resistance table, 24... Engine section resistance table,
25... Memory, 26... Throttle section resistance calculation means, 27... Engine section resistance calculation means, 28... Intake system time constant calculation means, 29... Intake pipe internal pressure calculation means, 30... - Primary delay processing means, 31... Filling air amount calculation means, 32... Actual engine intake air ff1R output means, 33... Fuel T31 injection means, 34... Fiery timing calculation means . Patent applicant: Fuji Heavy Industries Co., Ltd. Agent: Nobu Kobashi, Jundo Patent attorney: Shinyan Murai 4 Figure 5 F, Aya Nro 4% IN L! fI', j Figure 7 (Volunteer to write amended procedures) June 4, 1985 Director General of the Patent Office EEI Akira Yudono 1986
Patent Application No. 104413 2, Name of the invention Engine control device 3, Relationship with the case of the person making the amendment Patent Applicant: 1-7-2-4, Nishi-Shinjuku, Shinjuku-ku, Tokyo, Agent 5, Subject of the amendment (1) Full text of the specification (2) Contents of amendments to Figure 5 and 6 of the drawings (1) The entire text of document M will be amended as shown in the attached sheet. (2) Figure 5 of the drawings shall be corrected as shown in the attached sheet. (Amendment) Description 1, Title of the invention Engine control device 2, Claims In an engine equipped with an air flow meter upstream of the chamber of the intake pipe and a throttle opening sensor, the dynamic characteristics of the engine intake system are The engine part resistance R1 is a function determined by the throttle opening degree, and the engine part resistance R2 is
is a function of the engine speed, and the upstream pressure PO of the throttle valve and the capacity C of the chamber downstream of the throttle valve and the intake pipe are stored in memory as constants and modeled equivalently. Using an equivalent model, the intake pipe pressure is constantly estimated from the steady state to the transient state based on the throttle opening detected by the throttle opening sensor and the engine speed, and from this estimated intake pipe pressure, the intake pipe pressure is estimated during the transient state. Capacity C of the chamber downstream of the throttle valve and the intake pipe
The amount of air filled in the engine is estimated, and the amount of intake air measured by this estimated amount of charged air and the air flow meter is determined. Based on this estimated amount of actual engine intake air and the engine speed, the amount of fuel is calculated. An engine control device characterized by determining injection amount and ignition timing. 3. Detailed Description of the Invention (Field of Industrial Application) This invention provides a fuel injection engine that has a chamber or surge tank downstream of a throttle valve in the intake system and is equipped with an air flow meter. The present invention relates to an engine control device that controls fuel injection amount and ignition timing based on the number of fuel injections and ignition timing.

[Conventional technology]

Recently, fuel injection devices using air flow meters have been widely used in automobile engines.In this case, an air flow meter such as a hot wire type is installed upstream of the throttle valve to control the flow rate of air taken into the engine. Qa is accurately detected and the fuel amount 'r1. That is, Tp=Qa/N where the fuel injection pulse width TD is the engine rotation speed Ne
By calculating in the form of e, etc. and driving the injector by the injection pulse width 'l''p, fuel is supplied to the engine with extremely high accuracy.In addition, when controlling the ignition timing including the ignition timing, the ignition timing In many cases, this injection pulse width Tp is used as data for determining the negative cylinder in the calculation of the intake air amount Qa.Therefore, high accuracy is required when measuring the intake air amount Qa.Recently, air flow meters are also equipped with sensors. There is a tendency for wire-type air flow meters and the like to be used because of their high responsiveness. However, the air flow meter is only located upstream of the throttle valve, and does not directly measure the amount of air taken into the engine. For example, when the throttle valve changes from closing to opening, the amount of air flowing into the engine increases and at the same time the pressure in the chamber downstream of the throttle valve and the intake pipe also increases, so the air flow required for this pressure increase also increases. It will be measured by a meter. In other words, the air flow meter on the upstream side of the throttle valve measures an amount of air that is greater than the amount of air flowing into the engine when the throttle valve is closed and opened, albeit momentarily. It appears as a chute, and its amount increases as the volume of the chamber downstream of the throttle valve and the intake manifold increases, and the volume of the chute increases with the use of highly responsive sensors such as hot wire air flow meters. On the other hand, in MPI (multi-point injection), the injector (fuel injection valve) is located downstream of the intake manifold, so if the fuel is injected according to the measured amount of air, the air flowing into the engine will If more fuel is supplied, the air-fuel ratio A/F will become richer rapidly, resulting in an increase in CO and HC in the exhaust gas.In severe cases, over-richness will reduce engine output and drive the engine. There were problems such as a worsening of the feeling. Furthermore, in the case of an engine flash suppression device that controls the ignition timing as well, the ignition timing may be momentarily retarded, resulting in a reduction in engine output and deterioration in emissions. Note that when the throttle valve is open or idle, the air-fuel ratio A
/F and ignition timing! ! Problems such as deviation from t 56 ffi occur. For this reason, as shown in Japanese Patent Application Laid-Open No. 57-73831, for example, by detecting the movement of the throttle valve and correcting the fuel injection pulse width TD calculated based on the output of a hot wire type air flow meter, This solves the problem of engine malfunction due to changes in the appropriate air-fuel ratio due to sudden changes in opening, improves responsiveness during acceleration, and prevents misfires and rattles during deceleration. Ta. Furthermore, the method disclosed in Japanese Patent Application Laid-Open No. 59-170428 calculates the basic fuel injection amount calculated from the intake air amount and the engine rotational speed based on the change l of the signal voltage from the real wire type air flow meter with respect to time. The increase/decrease processing is performed to obtain the same effect as the above conventional example.

[Problems to be solved by the invention]

Conventionally, problems caused by changes in the appropriate air-fuel ratio due to sudden changes in throttle valve opening have been corrected based on the movement of the throttle valve or the amount of change in signal voltage from a hot wire air flow meter over time. However, since the system was configured to indirectly estimate and correct errors in detecting the intake air amount to the engine that occur during transient periods, it was not possible to accurately follow changes in the state of the intake system. Although a certain correction effect can be obtained, there is a problem in that the air-fuel ratio cannot be sufficiently maintained at an appropriate value. This invention was made in order to solve the above-mentioned problems of the conventional example, and eliminates the measurement error in the amount of intake air caused by the capacity of the chamber downstream of the throttle valve and the intake manifold that occurs when the throttle valve is suddenly opened and closed. Reduce and measure the amount of intake air more accurately! & An object of the present invention is to provide an engine control device that can maintain appropriate fuel injection amount and ignition timing.

[How to solve problems]

In order to achieve the above object, the present invention provides an air flow meter upstream of the chamber of the intake pipe, and in an engine equipped with a throttle opening sensor, the dynamic characteristics of the engine intake system are determined by the throttle resistance R1 depending on the throttle opening. As a function to be determined, the engine resistance R2 is a function of the engine speed, and the upstream pressure po of the throttle valve and the capacity C of the chamber and intake pipe downstream of the throttle valve are stored as constants in advance and are equivalent to each other. Using this equivalent model, the intake pipe pressure is constantly estimated from the steady state to the transient state based on the throttle opening detected by the throttle opening sensor and the engine speed, and this estimated intake pipe pressure is Estimate the amount of air filled in the chamber downstream of the throttle valve and the capacity C of the intake pipe during a transient period from the pressure, calculate this estimated amount of filled air and the amount of intake air measured by the air flow meter, and The fuel injection amount and ignition timing are determined based on the estimated actual engine intake air amount and the engine speed.

[For production]

The engine control device according to the present invention grasps the dynamic characteristics of the air in the intake pipe, replaces it with an electric circuit and stores it in the memory in the control device, and adjusts the pressure in the intake pipe to the throttle opening and engine speed. The amount of air filled into the chamber downstream of the throttle valve and the intake pipe during transient periods such as opening and closing of the throttle is determined by the fluctuation rate of the estimated pressure inside the intake pipe and the capacity inside the chamber downstream of the throttle valve and the intake pipe. The amount of air actually taken into the engine is estimated by adding or subtracting the estimated amount of charged air to the amount of intake air measured by the air flow meter, and the amount of air actually taken into the engine is estimated. The basic fuel injection amount is calculated based on the , and the optimal ignition timing is found through a map search, etc.

【Example】

1 to 7 are diagrams showing one embodiment of the present invention, in which FIG. 1 is a system diagram of an engine control device, and FIG. 2 is a model of the engine intake system and an equivalent model replaced with an electric circuit. 3 is a block diagram showing the configuration of the processing means of the engine control device, FIG. 4 is a diagram showing the setting of the throttle resistance R1 with respect to the throttle opening, and FIG.
The figure shows the setting of engine part resistance R2 with respect to the engine rotation speed, Figure 6 is a flowchart diagram showing the operation, and Figure 7
The figure is a transient response diagram showing changes in each data during a transient period. In Fig. 1, 1 is the engine, 2 is the intake pipe including the manifold, 3 is the chamber downstream of the throttle valve, 4 is the throttle valve, 5 is the injector (fuel injection valve), 6 is the ignition coil, and 10 is the hot wire type. 11 is a throttle opening sensor, 12 is a water temperature sensor, 13 is a crank angle sensor, 14 is a B elementary sensor,
20 is an engine control device consisting of a microcomputer. In such a system, the engine control device 20
Intake air amount Q measured by air flow meter 10
a and the engine rotational speed Ne determined by the signal from the crank angle sensor 13.
1, that is, the injection pulse width TD, Tp = K - Qa
/Ne, with correction based on the cooling water temperature detected by the water temperature sensor 12, and further by the B cable sensor 1.
performs feedback correction based on the output from 4, drives the injector 5 with the corrected injection pulse width Tp,
The amount of fuel corresponding to the intake air amount Qa, for example, is injected to provide a stoichiometric air-fuel ratio A/F. Further, the optimal ignition timing corresponding to the measured intake air amount Qa and engine speed Ne is determined by map search or the like, and ignition is performed via the ignition coil 6. In this control system, a spike-like overshoot or undershoot occurs in the measured intake air amount Qa due to the capacity C of the chamber 3 downstream of the throttle valve and the intake pipe 2 during transient periods due to the opening and closing of the throttle valve 4. , the air flow meter 10 measures a value different from the air amount Qe actually taken into the engine 1. In order to perform this correction, the engine control device 20 stores a model of the dynamic characteristics of the intake system as shown in FIG. The model of the intake system shown in FIG. 2(a) is based on the intake air amount Qa@−current value measured by the air flow meter 10, with the suction side pressure Po ('; atmospheric pressure) set to the power supply voltage ■0. To, slot 71
``The flow path resistance of the throttle section according to the opening degree of the throttle valve 4 is set as variable resistance R1, the engine section resistance according to the engine speed is set as variable resistance R2, and the volumes of the chamber 3 and intake pipe 2 downstream of the throttle valve are set as variable resistance R1. The capacitor capacity C is the air iQc that fills the volume of the chamber 3 and the intake pipe 2 downstream of the throttle valve during transient periods, and the current value Ic is the intake air amount Qe flowing into the engine 1. The internal pressure P is replaced by the voltage ■ and approximated as an equivalent model as shown in Fig. 2 (b). , the transient response of the voltage ■ after . The value is tentative as shown in Fig. 4, and is stored in the memory in a table with the throttle opening degree θ as a lattice.The engine resistance R2 is expressed as P/Qe according to the engine speed Ne. The value is as shown in Fig. 5, and is stored in the memory in a table with the engine speed Ne as a grid.In this way, the voltage ■, that is, the intake pipe pressure P, is determined by the time constant τ.
Since it can be approximated as a first-order lag system of =C-R,・R2/ (R+ +R2), the throttle resistance R1 can be expressed as a function determined by the throttle opening θ, the engine resistance R2 can be expressed as a function of the engine speed Ne, and , suction side pressure PO
If the capacity C in the chamber 3 downstream of the throttle valve and the intake pipe 2 are stored as constants in the memory, and a first-order delay processing means is provided in the engine control device 20, the intake pipe pressure P can be estimated. can do. Then, by calculating the time differential of this pressure P, the amount of filling air QC in the chamber 3 downstream of the throttle valve and the intake pipe 2 during a transient period can be calculated as C, dp/dt, and the actual intake air of the engine 1 can be calculated as follows. It is determined by the quantity Qe eQa - QC, and it becomes possible to accurately determine the fuel f1 injection quantity and ignition timing without being affected by overshoot or undershoot of the measured intake air quantity Qa that occurs during transition. The above arithmetic processing is performed by various means built into the engine control device 20 as shown in FIG. Engine speed Ne
seek. Reference numeral 22 denotes a measured intake air amount calculation means, which converts the voltage signal from the hollow one-wire type air flow meter 10 into intake air iQa. 23 is throttle part resistance R1
24 is an engine resistance table that stores engine resistance R2 and engine rotational speed Ne as a lattice. 25 is a chamber 3 downstream of the throttle valve and the intake air. A memory in which the capacity C of the pipe 2 and the suction side pressure Po (approximately atmospheric pressure) are stored in advance, 26 is a throttle section resistance calculation means, 27 is an engine section resistance calculation means, 28 is an intake system time constant calculation means, 2 One is the intake pipe pressure P in steady state.
The intake pipe internal pressure calculation means 30 calculates the intake pipe internal pressure P during a transient period by performing first-order delay processing on the intake pipe internal pressure PB.
(t), 31 is a charging air amount calculation means, 32 is an actual engine intake air amount calculation means, 33
34 is a fuel injection amount calculation means and an ignition timing calculation means. Next, the operation of the engine control device 20 configured as described above will be explained with reference to the flowchart of FIG. 6 and the transient response diagram of FIG. 7. Engine system T! The R equipment W20 converts the voltage signal from the air flow meter 10 into a measured intake air amount Qa in the measured intake air amount calculation means 22.Step 5ioi When opened, a signal Qa with a spike-like overshoot as shown in FIG. 7(b) is output. Then, the throttle opening signal θ is output from the throttle opening sensor 11, and the engine rotational speed N is output from the engine rotational speed calculating arm 21.
Step 5102), the throttle resistance calculation means 26 reads out the preset throttle resistance R1 from the throttle resistance table 23 using the throttle opening θ as an address signal, and the engine resistance calculation means 27 reads the throttle resistance R1 set in advance from the throttle resistance table 23. , the preset engine resistance R2 is read out from the engine resistance table 24 using the engine rotational speed signal Ne as an address signal (step 5103). Next, the intake system time constant calculation means 28 calculates the first-order lag time constant τ of the intake system based on the read throttle resistance R1, engine resistance R2, and capacitance C stored in the memory 25 (step 5104). In addition, the intake pipe pressure calculation means 29 calculates, based on the resistance R1+R2 and the intake side pressure Po stored in the memory 25,
Calculate the intake pipe pressure P13 in a steady state (step 5105), and apply first-order lag processing using a time constant τ to this intake pipe pressure PI3 every calculation period Δ in the first-order lag processing means 30 to calculate the intake pipe pressure during a transient state. P(t) (step 5106), and the zero-order filling air amount calculation means 31 estimates the intake pipe internal pressure P as shown in FIG. 7(d). C, the amount of filling air Qc filled in the chamber 3 downstream of the throttle valve and the intake pipe 2 during a transient period is determined (step 31
07), estimated as shown in FIG. 7(e). Step 9108 ), and the actual engine intake air jtQe is estimated as shown in Figure 7). The actual engine intake air amount Qe obtained in this way does not have a spike-like overshoot like the measured intake air ff1Qa, and due to this and the engine speed Ne,
The fuel injection amount calculation means 33 calculates Tp = K - Qe /N
Fuel injection in the form of e -117i, i.e. injection pulse f
eTp is calculated (step 5109), and the air-fuel ratio A/F as shown in FIG. 7 ((1)) is obtained even during the transient period, and a large air-fuel ratio A as shown in FIG. 7 (C) showing the conventional example is obtained. /F does not fluctuate. Also, the ignition timing calculating means 34 also calculates the maximum M ignition timing by map search etc. based on the actual engine intake air amount Qe corresponding to the actual load and the engine speed Ne. (Step 5110), so no unnecessary retardation occurs during a transition. 6 Although the above embodiment describes a transition during which the throttle valve is suddenly closed, a similar operation is performed during a transition when the throttle valve is suddenly closed. It is possible to suppress fluctuations in the air-fuel ratio A/F toward the lean side, and to prevent inconveniences caused by deviations from the optimum value of ignition timing.

【Effect of the invention】

As is clear from the above description, the engine control device of the present invention estimates the intake pipe internal pressure by considering the capacity of the chamber downstream of the throttle valve and the intake pipe, and further estimates the amount of air actually taken into the engine. Since the estimation is made, even during transient times such as opening and closing of the throttle valve, the influence of overshoot and undershoot on the measured intake air amount due to the capacity is eliminated, and the deviation from the air-fuel ratio setting value is minimized. The generation of CO and HC in the exhaust gas can be prevented. In addition, it is possible to stabilize the output and improve the driving feeling. Furthermore, the deviation of the ignition timing from the appropriate value can be minimized, resulting in improved driving feel and emissions. 4. Brief description of the drawings Figures 1 to 7 are diagrams showing one embodiment of the present invention. Figure 1 is a system diagram of an engine control device, and Figure 2 is a model (a) of an engine intake system. Fig. 3 is a block diagram showing the configuration of the processing means of the engine control device, and Fig. 4 shows the setting of the throttle resistance R1 with respect to the throttle opening. Figure 5 is a diagram showing the setting of engine resistance R2 with respect to engine speed, Figure 6 is a flowchart diagram showing the operation, and Figures 7 (a) to (1) are diagrams showing changes in each data during transition. FIG. DESCRIPTION OF SYMBOLS 1... Engine, 2... Intake pipe, 3... Chamber downstream of throttle valve, 4... Throttle valve, 5...
Injector, 10...Air flow meter, 11...
・Throttle opening sensor, 13... Crank angle sensor, 20... Engine control! 11 device, 23... Throttle resistance table, 24... Engine resistance table, 25... Memory, 26... Throttle resistance calculation means, 27... Engine resistance calculation means, 28.
...Intake system time constant calculation means, two...Intake pipe pressure calculation means, 30.First-order delay processing means, 31.Charging air amount calculation means, 32.Actual engine intake air amount calculation Means, 33...burn f! Injection amount calculation means, 34...Ignition timing calculation means. Patent Applicant Fuji Heavy Industries Co., Ltd. Agent Patent Attorney Nobu Kobashi 14 Patent Attorney Shinji Murai, Go Rotation% Ne

Claims (1)

[Claims] In an engine equipped with an air flow meter upstream of a throttle valve, an injector downstream of an intake pipe, and a throttle opening sensor, the dynamic characteristics of the engine intake system are determined by the throttle resistance R_1 determined by the throttle opening. As a function, engine resistance R
_2 is a function of the engine speed, and the upstream pressure P_0 of the throttle valve and the capacity C of the chamber and intake pipe downstream of the throttle valve are stored as constants in advance and modeled equivalently, and this equivalent model is Using this, the intake pipe pressure is always estimated from the steady state to the transient state based on the throttle opening detected by the throttle opening sensor and the engine speed, and from this estimated intake pipe pressure, the throttle valve is adjusted during the transient state. Estimate the amount of air filled in the downstream chamber and the capacity C of the intake pipe, calculate this estimated amount of filled air and the amount of intake air measured by the air flow meter, and calculate the estimated amount of intake air in the actual engine. An engine control device characterized in that a fuel injection amount and an ignition timing are determined based on the engine speed and the engine speed.