JPH0158335B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control device for an internal combustion engine, and more particularly to a control device for controlling an internal combustion engine based on a dynamic model representing a dynamic state of the engine.

Well-known conventional control devices include, for example, methods for controlling fuel such as (1) a feedback control method, and (2) a program control method.

However, the feedback control method has the problem of slow control speed and cannot cope with transient operation of the internal combustion engine, and the program control method has the problem of not being able to compensate for variations in control equipment and aging deterioration of the internal combustion engine.

For example, a method of feedback controlling the air-fuel ratio using an oxygen sensor is well known, such as in US Pat. No. 3,738,341. In this method, when the output of the oxygen sensor deviates from a set value, the air amount or fuel amount is controlled to keep the air-fuel ratio constant. Now, if the amount of air flowing into the internal combustion engine suddenly changes, if the amount of fuel is controlled after detecting the output of the oxygen sensor, the control speed will be slow and the initial amount of fuel will become small, causing the internal combustion engine to misfire. Therefore,
The problem is that feedback control does not work effectively during transient operation.

Further, a program control method in which a fuel amount is stored in a memory and controlled by searching for the fuel amount using predetermined parameters is known from US Pat. No. 3,689,755 and the like. This method has a problem in that an accurate fuel amount cannot be obtained because the fuel amount is determined based on the detected parameter value regardless of variations in the control equipment or deterioration of the internal combustion engine.

An object of the present invention is to provide a control device for an internal combustion engine that has a fast control speed and high control accuracy.

The features of the present invention are (a) operating state detection means 2, 19, 22, 26, 27 that detects the operating state of the internal combustion engine 9 and generates a plurality of input signals that can be calculated; (b) the operating state of the internal combustion engine 9; Actuator means 13, 17 for controlling operation (c) Digital calculation means having the following functions; (c-1) Expressed by the following internal descriptive equation defining a dynamic model representing the dynamic state of the internal combustion engine 9: Memory function 11, 1 for storing programs
2; () x〓 _i = A・x _i +B・u _i : State equation () y _i =C・x _i : Observation equation x _i : (x ₁ , x ₂ , ... x _o : state variable) u _i : (u ₁ , u ₂ , ... u _o : control input amount) y _i : (y ₁ , y ₂ , ... y _o : control output amount) A, B, C: Coefficient (c-2) Above A required output amount determined based on an arbitrary input signal of the operating state detection means is determined as a control output amount (y i ), and the control output amount (y _i ) is determined as a control output amount (y _i ).
_The state variable (x _i ) determined by _the observation equation is determined using The operation of the internal combustion engine 9 is controlled based on the input quantity (u _i ), and the state variable (x _i ) determined by the state equation using the control input quantity (u _i ), and this determined The dynamic model of the internal combustion engine is determined by determining the control output amount (y _i ) determined by the observation equation using the state variable (x _i ), and the control output amount (y _{i )} of the dynamic model is determined. ) and the actual output quantity (y _a ) measured based on at least one input signal of the operating state detection means, the coefficients of the internal description equation are repeatedly modified so that the relationship becomes a predetermined relationship. A function 10 for identifying the actual state of the internal combustion engine and a dynamic model of the internal combustion engine; (c-3) controlling the required output amount determined based on an arbitrary input signal of the operating state detection means; (y _i ), and the control output amount (y _i )
The state variable (x _i ) determined by the latest observation equation for which the _coefficient has been corrected is obtained using function 1 of determining the control input amount (u _i ) determined by the state equation of and outputting it to the actuator means;
0; in a control device for an internal combustion engine.

Examples using the present invention will be described below.

First, the concept of a dynamic model of an internal combustion engine expressed by internal descriptive equations will be explained.

Now, when accelerating the internal combustion engine by changing the throttle valve opening from θ ₁ to θ ₂ as shown in Figure 1,
It is desirable to vary the fuel along a line from point F to point E. However, as the throttle valve opening degree changes from θ ₁ to θ ₂ , the fuel supplied to the internal combustion engine does not reach the combustion chamber immediately, so the torque T changes from point F to point F′ to point E. In this way, the torque T
In order to prevent a momentary drop in torque T, the drop in torque T can be reduced by increasing the amount of fuel.

Now, the amount of fuel supplied to the internal combustion engine is u (control input), the amount of fuel necessary for the internal combustion engine is x (state variable), and the output of the internal combustion engine is y (control output).
Then, () x〓=A・x+B・u: Equation of state
...(1) () y=C・x: Observation equation A, B, C: Internal descriptive equations such as coefficients can model the dynamic state of the internal combustion engine as a dynamic model.

When controlling the internal combustion engine using this internal description equation, the procedure is first to obtain the output y (control output) of the internal combustion engine, which is determined based on an arbitrary input signal representing the operating state of the internal combustion engine.

The output y (control output) of this internal combustion engine is, for example,
This is an output that corresponds in advance to the amount of depression of the accelerator pedal, and is stored in memory in advance. Therefore, the output y (control output) of the internal combustion engine is retrieved from the memory in accordance with the amount of depression of the accelerator pedal.

Next, using the output y (control output) of the internal combustion engine, the required fuel amount x (state variable) determined by x=y/C is determined from the observation equation.

Next, using this required fuel amount x (state variable), the supplied fuel amount u (control input) determined by the equation of state is determined by u=(x〓−A・x)/B, and fuel is supplied to the internal combustion engine. .

In this way, by modeling the dynamic state of the internal combustion engine as a dynamic model using internal description equations, it becomes possible to supply appropriate fuel to the internal combustion engine.

Incidentally, by modeling the dynamic state of the internal combustion engine using such an internal description equation, it is possible to supply appropriate fuel to the internal combustion engine, but the problem here is the coefficients of the internal description equation.

In other words, this coefficient changes depending on the state of the internal combustion engine, such as fuel adhesion in the intake pipe or transportation delay, so the actual state of the internal combustion engine and the state of the dynamic model of the internal combustion engine cannot be identified. Therefore, it is necessary to modify this coefficient.

The present invention was proposed from this viewpoint, and the idea will be explained below.

As a specific example, a system that controls the amount of fuel and air to keep the air-fuel ratio constant will be described.

Now, if the amount of fuel required for the internal combustion engine is x ₁ (state variable) and the amount of air required for the internal combustion engine is x ₂ (state variable), then ()x〓 ₁ = A・x ₁ +B・u ₁ () x〓 ₂ =C・x ₂ +D・u ₂ () y _n =E・x ₁ +F・x ₂ 〓 | 〓 : State equation : Observation equation ……(2) u ₁ : Supply fuel amount (control input) u ₂ : Supply air amount (control input) y _n : Internal combustion engine output (control output) A, B: coefficients C, D: coefficients E, F: define a dynamic model that represents the dynamic state of the internal combustion engine as shown in the coefficients An internal description equation is given. here,
The above coefficients change depending on the state of the internal combustion engine.

Then, as described above, the supplied fuel amount u ₁ is determined based on the internal descriptive equation that defines the dynamic state of the internal combustion engine.
(control input), supply air amount u ₂ (control input) can be determined and supplied to the internal combustion engine.

However, as described above, there is a problem in that the actual state of the internal combustion engine and the state of the modeled dynamic model of the internal combustion engine cannot be identified.

Therefore, in the present invention, this problem was solved by adopting the following method.

The configuration is shown in FIG. 7, and will be explained below based on this.

First, in block B1, a required output amount determined based on an arbitrary input signal of the operating state detection means is determined as the control output amount y _n . Then, using this control output amount y _n , the amount of fuel x ₁ required for the internal combustion engine and the amount of air x ₂ required for the internal combustion engine, which are state variables determined by the observation equation, are determined. Next, using the determined state variables x ₁ and x ₂ , the supplied fuel amount u ₁ and the supplied air amount u ₂ are determined by the state equation.
Based on this control input amount, fuel and air are supplied to actually operate the internal combustion engine.

On the other hand, in block B2, the amount of fuel required for the internal combustion engine x ₁ and the amount of air required for the internal combustion engine, which are state variables determined by the state equation from the amount of supplied fuel u ₁ which is the control input amount, and the amount of air required for the internal combustion engine from the amount of supplied air u ₂ . x ₂ is determined, and the control output amount y _n determined by the observation equation is determined using the determined state variables x ₁ and x ₂ to determine the dynamic model of the internal combustion engine.

Then, compare the control output amount y _n of the dynamic model with the actual output amount y _a measured based on at least one input signal of the operating state detection means (how to determine the actual output amount will be described later). Can be done.

Therefore, in block B2, the engine's controlled output amount y _n and the engine's actual output amount y _a are compared, and if the difference does not have a predetermined relationship (for example, they do not match), A of the internal description equation described above is applied. ,B,C...
..., etc., so that the control output amount y _n and the actual engine output amount y _a have a predetermined relationship (for example, they match). Modification of the coefficients of this internal description equation is performed repeatedly to identify the actual state of the internal combustion engine and the dynamic model of the internal combustion engine.

Next, in block B1, the required output amount determined based on the arbitrary input signal of the operating state detection means is determined as the control output amount y _n , as in the previous step, and the coefficients are corrected using the control output amount y _n . The amount of fuel required for the internal combustion engine x ₁ and the amount of air required for the internal combustion engine x ₂ are the state variables determined by the latest observation equation.
seek. Next, using the obtained state variables x ₁ and x ₂ , the supplied fuel amount u ₁ and the supplied air amount u ₂ , which are the control input amounts determined by the latest state equation whose coefficients have been corrected, are determined and calculated as described above. Output to actuator means.

Therefore, since the actual state of the internal combustion engine and the latest dynamic model of the internal combustion engine are identified, appropriate amounts of supplied fuel u ₁ and supplied air amount u ₂ can be determined based on the internal description equations. Become.

In addition, the control input and control output are fuel,
Although it has been explained as air and engine output, it is not limited to this and can be used in a wide sense of control.

Here, in this embodiment, the generated torque is calculated to obtain the actual output amount y _a of the internal combustion engine, and the generated torque can be calculated by the following method.

In an internal combustion engine, the angular velocity ω of the crankshaft varies from cycle to cycle due to combustion fluctuations, as shown in FIG. For example, in the case of a four-cylinder engine, explosion takes place in each cycle, so the angular velocity ω increases in the middle of the explosion stroke and reaches the maximum angular velocity ω ₁ , and before and after that, the angular velocity decreases to the minimum angular velocity ω ₂ . is repeated.

As shown in FIG. 3, the method for detecting this angular velocity ω is to provide a large number of protrusions 101 on the crankshaft 1, input a signal from a pickup 2 as an operating state detection means to a pulse counter 6, and select an arbitrary rotation angle. It is sufficient to store the rotation pulses at the time in the registers 7 and 8 and obtain them.

The difference Δω (Δω = ω ₁ − ω ₂ ) between the maximum angular velocity ω ₁ and the minimum angular velocity ω ₂ of the angular velocity ω obtained in this way is equal for each cycle when the combustion state does not change, but when the combustion state changes It can be understood that Δω differs for each cycle according to the above.

Now, the relationship between the generated torque T of the internal combustion engine and the angular velocity ω, omitting the coefficient, is Idω/dt=(T-T _B )...(3) I: Inertia of the internal combustion engine T: Generated torque T _B of the internal combustion engine: Load torque of internal combustion engine t: Elapsed time. As shown in Figure 4, ω ₁ −ω ₂ ∝1/I(T−T _B ……(4) ω ₁ −ω _{2 2A} ∝1/IT _B ……(5), and (ω ₁ −ω _2A )∝(ω ₂ −ω ₁ )＋T _B +(T− _B )/I……
(6) becomes. Therefore, now for any t ₀ time (ω ₁
−ω ₂ ) from equation (6), we get Σ(ω ₁ −ω ₂ )=t ₀ (T−T _B )+T _B /2I ……(7), and the integrated value is a function only of the generated torque T. As a result, it is no longer affected by the rotation speed.

That is, the generated torque T can be determined from Δω, which becomes the actual output amount y _a of the internal combustion engine, and is compared with the control output amount y _n of the dynamic model as described above.

In addition, as shown in Fig. 5, P ₁ of torque T = 2
If the internal description equation shown in equation (2) is used to control the amount of fuel and air to increase from point P ₁ to point P ₂ with torque T = 4 from point P ₂ , the amount of fuel will be Hunting of the output of the internal combustion engine can be prevented by controlling the amount of air in association with the amount of air.

That is, in the conventional system, even if the amount of air is increased, the amount of fuel does not immediately increase, and if the amount of air is further increased to ensure torque, the amount of fuel increases and the torque exceeds the set value. For this reason, even if the air amount is reduced, the fuel amount does not decrease immediately, and the air amount is reduced too much, which also causes hunting in the output of the internal combustion engine. Hunting can be prevented by controlling the air amount and fuel amount in consideration of the delay in the fuel amount and air amount using the internal description equation as described above.

Next, an example of a control system based on the above concept will be described.

The control system will be explained with reference to FIG. 9 is an internal combustion engine, 10 is a microcomputer, and an instruction program, internal description equations (1) and (2), fixed values, etc. are stored in advance in a storage device 11.

Also, state variables x ₁ , x ₂ , ... and coefficients A, B, C
. . . etc. are stored in the register group 12. This allows the microcomputer 10 to calculate internal description equations such as equations (1) and (2). 1
Reference numeral 3 denotes a fuel control device that controls the input amount of an injection valve or the like (actuator means). The amount of fuel can be controlled by duty-controlling the current of the electromagnetic solenoid of the injection valve 13 and changing the duty ratio from the microcomputer 10. Fuel is sucked from the tank 16 by the pump 15, the pressure is controlled by the regulator 14, and the fuel is supplied to the internal combustion engine 9 from the injection valve 13. 17 is a bypass valve (actuator means), and 18 is an air amount control device that controls the amount of air, which is the input amount, by a throttle valve. The amount of air can be controlled by controlling the current of the electromagnetic solenoid of the bypass valve 17 using the microcomputer 10. Reference numeral 19 denotes a hot wire flowmeter as an operating state detection means, which measures the amount of air flowing in through the air cleaner 20 as an input amount. Reference numeral 27 denotes an intake pressure sensor as an operating state detection means.

By inputting the above-mentioned air amount signal, fuel amount signal (duty ratio), accelerator depression amount, etc. to the microcomputer 10 and giving these as inputs to the internal description equation, the state equation and observation equation are Variables, control output amounts, control input amounts, and coefficients can also be calculated from time to time and output to corresponding registers in the register group 12. A shift position sensor 22 as operating state detection means is attached near the transmission 21 and this signal is input to the microcomputer 10. Now, input the signal from the pick-up 2 to the microcomputer 10 and calculate Δω.
Find the actual measured value. This is possible by storing ω ₁ in a corresponding register of the register group 12 and storing ω ₂ in another register, and calculating Δω from ω ₁ - ω ₂ .

Therefore, as mentioned above, the microcomputer uses the required output amount determined based on the arbitrary input signal of the operating state detection means as the control output amount.
Find it as y _n . Then, using this control output amount y _n , the amount of fuel required for the internal combustion engine x ₁ and the amount of air required for the internal combustion engine are state variables determined by the observation equation.
Find x ₂ . Next, the obtained state variables x ₁ , x ₂
Using this, the supplied fuel amount u ₁ and supplied air amount u ₂ , which are control input amounts determined by the state equation, are determined, and based on these control input amounts, fuel and air are supplied to actually operate the internal combustion engine.

Next, the supplied fuel amount u ₁ which is a control input amount,
The fuel amount x ₁ required for the internal combustion engine and the air amount x ₂ required for the internal combustion engine, which are state variables determined by the state equation, are determined from the supplied air amount u ₂ , and the determined state variables x ₁ and x ₂ are The dynamic model of the internal combustion engine is determined by determining the control output quantity y _n determined by the observation equation using

Then, compare the control output amount y _n of the dynamic model with the actual output amount y _a measured based on at least one input signal of the operating state detection means (how to determine the actual output amount will be described later). Can be done.

Therefore, when comparing the engine's controlled output amount y _n and the engine's actual output amount y _a , if the difference does not have a predetermined relationship (for example, they do not match), then A, B of the internal description equations above, The coefficients such as C... are corrected so that the control output amount y _n and the actual engine output amount y _a have a predetermined relationship (for example, they match). Modification of the coefficients of this internal description equation is performed repeatedly to identify the actual state of the internal combustion engine and the latest dynamic model of the internal combustion engine.

Next, as before, the required output amount determined based on the arbitrary input signal of the operating state detection means was determined as the control output amount y _n , and the coefficient was corrected using the control output amount y _n . The amount of fuel required for an internal combustion engine is a state variable determined by the latest observational equation.
x ₁ and the amount of air required for the internal combustion engine x ₂ . Then, using the obtained state variables x ₁ and x ₂ , the supplied fuel amount u ₁ and the supplied air amount u ₂ , which are control input amounts determined by the latest state equation whose coefficients have been corrected, are determined and the actuator is Output to means.

Therefore, the actual state of the internal combustion engine and the modeled state-of-the-art dynamic model of the internal combustion engine are identified, and the appropriate amount of fuel to be supplied is calculated based on the internal description equation.
u ₁ and the supplied air amount u ₂ are determined and supplied to the internal combustion engine, making it possible to optimally control the internal combustion engine over a wide operating range. This method can optimally correct for fuel delays caused by the effects of internal combustion engine temperature, etc. As shown in FIG. 6, the starter 23 is rotated by applying the voltage of the battery 25 to the starter 23 by operating the switch 24. As shown in FIG. This switch 24 is the microcomputer 1
It can operate with a command of 0. Butterfly 25
Water temperature sensor 2 as voltage and operating state detection means
Input the signal of 6 to the microcomputer 10,
The microcomputer 10 determines whether starting is possible or not based on voltage and water temperature signals. If the internal combustion engine can be started, it is determined whether the compression temperature reaches a limit value at which the internal combustion engine must be warmed up by cranking, and the fuel supply timing is determined. Due to the inertia of the starter and internal combustion engine, it takes a certain amount of time for the rotation during cranking to reach a steady state. By paying attention to this timing and supplying fuel, the internal combustion engine starts to explode and the rotation speed increases.

As can be understood from the above explanation, the present invention captures the internal combustion engine as a dynamic model, calculates the state variable determined by the observation equation using the control output amount determined based on the input signal, and uses the determined state variable. At the same time, the coefficients of the internal description equation are repeatedly corrected so that the relationship between the control output amount determined by the dynamic model of the internal combustion engine and the actual output amount is a predetermined relationship. By doing so, it is possible to increase the control speed and improve the control accuracy at the same time.

[Brief explanation of drawings]

Fig. 1, Fig. 2, Fig. 4, and Fig. 5 are characteristic diagrams for explaining the present invention, Fig. 3 is a block diagram for detecting the rotation speed, and Fig. 6 is an embodiment of the present invention. The control block diagram, FIG. 7, is a schematic diagram of the present invention. 2... pick up, 9... internal combustion engine, 10...
...Microcomputer, 12...Register, 1
3...Injection valve, 17...Bypass valve, 19...Hot wire flow meter, 22...Shift position sensor, 26...Water temperature sensor, 27...Intake pressure sensor.

Claims (1)

[Claims] 1 (a) Operating state detection means 2, 19, 22, 26, 27 that detects the operating state of the internal combustion engine 9 and generates a plurality of computable input signals; (b) The internal combustion engine Actuator means 13, 17 for controlling the operation of the internal combustion engine 9 (c) Digital calculation means having the following functions; (c-1) The following internal descriptive equations defining a dynamic model representing the dynamic state of the internal combustion engine 9 Memory function 11, 1 for storing the represented program
2; () x〓 _i = A・x _i +B・u _i : State equation () y _i =C・x _i : Observation equation x _i : (x ₁ , x ₂ , ... x _o : state variable) u _i : (u ₁ , u ₂ , ... u _o : control input amount) y _i : (y ₁ , y ₂ , ... y _o : control output amount) A, B, C: Coefficient (c-2) Above A required output amount determined based on an arbitrary input signal of the operating state detection means is determined as a control output amount (y i ), and the control output amount (y _i ) is determined as a control output amount (y _i ).
The state _variable (x _i ) determined by _the observation equation is determined using The operation of the internal combustion engine 9 is controlled based on the input quantity (u _i ), and the state variable (x _i ) determined by the state equation using the control input quantity (u _i ), and this determined The dynamic model of the internal combustion engine is determined by determining the control output amount (y _i ) determined by the observation equation using the state variable (x _i ), and the control output amount (y _{i )} of the dynamic model is determined. ) and the actual output quantity (y _a ) measured based on at least one input signal of the operating state detection means, the coefficients of the internal description equation are repeatedly modified so that the relationship becomes a predetermined relationship. A function 10 for identifying the actual state of the internal combustion engine and a dynamic model of the internal combustion engine; (c-3) controlling the required output amount determined based on an arbitrary input signal of the operating state detection means; (y _i ), and the control output amount (y _i )
The state variable (x _i ) determined by the latest observation equation for which the _coefficient has been corrected is obtained using Function 1 of determining the control input amount (u _i ) determined by the state equation of and outputting it to the actuator means.
0; A control device for an internal combustion engine.