JPS6371551A - Load torque estimating device for internal combustion engine - Google Patents

Abstract

PURPOSE:To improve the responsiveness and following performance in the feedback control by installing a load torque calculating means which calculates the load torque from the revolution speed, intake air pressure, and control quantity by using the parameters on the basis of the dynamic physical model of the internal combustion engine. CONSTITUTION:The revolution speed of an internal combustion engine M1 is detected M2, and the intake air pressure is detected M3, and the control quantity related to the adjustment of the intake air quantity is calculated M4. A load torque calculating means M5 which calculates the load torque of the internal combustion engine from the revolution speed, intake air pressure, and the control quantity by using the parameters set on the basis of the dynamic physical model of the internal combustion engine is set. Thus the responsiveness and following performance in the feedback control of the internal combustion engine can be improved.

Description

Detailed Description of the Invention Purpose of the Invention [Industrial Field of Application] The present invention constructs a dynamic physical model of an internal combustion engine, and uses parameters determined based on the physical model to determine the load of the internal combustion engine. The present invention relates to a load 1 to torque estimating device for an internal combustion engine that estimates torque.

[Prior Art] Conventionally, there has been a technology for constructing a dynamic model of an internal combustion engine by considering its internal state, and estimating the dynamic behavior of the internal combustion engine using state variables that define the internal state. Are known. For example, ``Idle rotational speed control method for internal combustion engine'' (Japanese Patent Application Laid-open No. 59-120751@publication) has been proposed.

In other words, a model of the dynamic characteristics of the internal combustion engine, actuator, and sensor υ is stored in a controller consisting of a microcomputer, etc., and the amount of air, ignition timing, fuel supply, and exhaust gas recirculation is calculated. Any one or a combination of two or more is used as the control input, and the idle rotation speed is used as the control output, and from the control input and the control output,
The state variable quantity representing the internal state of an internal combustion engine, etc., which is a dive model, is estimated, and the control human power value is determined using the estimated value and the integral value of the deviation between the target value and the actual value of the idle rotation speed. This is a technology that feedback controls the idle rotational speed of an internal combustion engine to a target value.

Here, the state variables representing the dynamic internal state of the internal combustion engine do not necessarily correspond to various physical quantities representing the actual internal state, but are used to simulate the internal combustion engine as a rest.

[Problems to be solved by the invention] By the way, for a complex object such as an internal combustion engine, it is difficult to theoretically and accurately obtain a dynamic model, and it is necessary to determine it experimentally in some way. Ta. Therefore,
In the above conventional technology, the relationship between each control input and control output is
A dynamic model of an internal combustion engine has been constructed by describing it using a transfer function matrix obtained near a certain reference setting value and linearly approximated, and determining the transfer function matrix using a so-called system identification method.

Therefore, as the dynamic 'E del of an internal combustion engine with nonlinearity, a linear model that holds true only during perturbations near the above reference setting value and does not necessarily have physical meaning has been adopted, so There was a problem that the dynamic model did not fit well.

Furthermore, since the state variable amount J1f was determined using parameters determined based on the dynamic model determined as described above, the state variable amount did not necessarily have physical meaning. For this reason, even if feedback control is performed in which a control amount is calculated from the state variable quantity using the optimum feedback gain, there is a problem in that the control characteristics are not necessarily improved.

Furthermore, since the estimated state variables have no physical meaning, the uses of the state variables are limited, and the state variables obtained by configuring a state observation device cannot be effectively used for multiple purposes. There was a problem.

The present invention utilizes parameters determined based on dynamic physics and [Del] constructed in accordance with the physical relationships of various quantities involved in the behavior of an internal combustion engine to control the load torque, which is a physical quantity that is difficult to measure, into a state. The object of the present invention is to provide an apparatus for estimating load torque of an internal combustion engine that calculates it as a variable quantity.

Structure of the Invention [Means for Solving the Problems] The present invention, which has been made in order to solve the above problems, as illustrated in FIG. Ml is approximated by a linear combination of at least the intake air pressure and the load torque, and the intake air pressure fluctuation per predetermined time of the internal combustion engine M1 is approximated by the product of at least the intake air pressure and the rotational speed of the internal combustion engine M1 and the intake air Dynamic physics of the internal combustion engine obtained by approximation by a linear combination of quantities - [An internal combustion engine load torque estimating device for estimating the load torque of the internal combustion engine M1 in accordance with Dell,
a rotational speed detection means M2 for detecting the rotational speed of the internal combustion engine M1; an intake air pressure horn detection means M3 for detecting the intake air pressure of the internal combustion engine M1; and a control involved in regulating the intake air amount of the internal combustion engine M1. The rotational speed detected by the rotational speed detection means M2 and the intake air pressure detection means are calculated using a control amount calculation means M4 that calculates the amount, and parameters set based on a dynamic physical model of the internal combustion engine. An internal combustion engine comprising: a load calculating means M5 for calculating the load of the internal combustion engine M1 from the intake air pressure detected by M3 and the control amount calculated by the control amount calculating means M4; The gist of this paper is an engine load torque estimation device.

The rotational speed detection means M2 detects the rotational speed of the internal combustion engine M1. For example, it can be constructed from a pulse gear fixed to the cam shirt i of the distributor of the internal combustion engine Ml and an electromagnetic pickup disposed close to and opposite to the pulse gear. For example, it may be the crankshaft (rotational speed lens 4 that detects the rotational speed of the foot) of the internal combustion engine M1.

The intake air pressure detection means M3 is for detecting one intake air of the internal combustion engine M1. For example, it can be realized by a semiconductor pressure sensor 4 disposed in the intake manifold or surge tank of the internal combustion engine M1.

The control amount calculation means M4 calculates a control amount involved in adjusting the intake air amount of the internal combustion engine M1. for example,
It can be configured to calculate the product of the intake air pressure and rotational speed of the internal combustion engine M1 and the tightening value of the effective cross-sectional area of the intake throttle.

The load torque calculation means M5 uses parameters set based on a dynamic physical model of the internal combustion engine M1.
The load torque is calculated from the rotation speed, intake air pressure, and control amount of the internal combustion engine M1.

Here, the dynamic physics-E del of the internal combustion engine can be constructed as follows, for example. First, from the equation (described above) regarding the energy balance of the internal combustion engine M1 in the operating state, a first approximation is made that expresses the rotational speed fluctuation per predetermined time of the internal combustion engine M1 by at least the intake air pressure and the load] ~ Silk linear combination. Find the formula. Next, from the equation describing the mass conservation of the intake air amount in the cylinder in the intake stroke of the internal combustion engine M1, we can calculate the intake air pressure fluctuation per predetermined time of the internal combustion engine M1 by at least the product of the intake air pressure and the rotational speed and the intake A second approximate expression expressed by a linear combination of air amounts is determined. Furthermore, based on the first approximation equation and the second approximation equation, a state equation (1) below and an output equation (2) below are derived.

X (k+1) = P-X (k) -N[2-u
(k)...(1) v (k) -T-X (k) -(2
) Equations (1) and (2> are expressed in a discrete system, and the subscript indicates the point of rimbling. Here, the state variable quantity X (k) is the load torque, rotation speed, and suction The element is air pressure, and input is allowed (k) is a control variable involved in adjusting the amount of intake air, and the output v, (k) is the rotational speed and 1 force of intake air. According to the above expressions (1) and (2> expressed in this way,
A dynamic physical model of internal combustion engine M1 is determined.

By the way, the load torque calculation means M5 is a so-called state observation device (observation arbor) in modern control theory,
The observer is constructed from the above equations (1) and (2). Various types of observers and their construction methods are known, such as "Basic System Theory" by Katsuhisa Furuta et al. (1976) published by Korotasha; 1959) is explained in detail by Ohmsha et al.

The control amount calculation means M4 and the load torque calculation means M5
For example, in addition to the well-known CPU, ROM, RAM
and other peripheral circuit elements as a logic operation circuit, and according to a predetermined processing procedure, both means M4. Achieving M5 may be possible.

[Operation] As illustrated in FIG. 1, the load torque estimating device for an internal combustion engine according to the present invention uses parameters set based on a dynamic physical model of the internal combustion engine M1 to estimate the rotational speed detection means M2. Detected rotational speed and intake air pressure detection means M3
The load 1 to torque calculation means M5 operate to calculate the load torque from the intake air pressure detected by the intake air pressure and the control amount calculated by the control amount calculation means M4.

That is, a load torque having a physical meaning is estimated in accordance with a dynamic physical model obtained by approximating the relationship between physical quantities involved in the behavior of the internal combustion engine M1.

Therefore, the load 1 herk estimating device for an internal combustion engine of the present invention works to suitably calculate the load 1 to herk, which is a physical quantity that is difficult to measure. The technical problems of the present invention are solved by each component of the present invention acting as described above.

[Embodiment] Next, a preferred embodiment of the present invention will be described in detail based on the drawings. FIG. 2 shows a system configuration of an engine control device that is an embodiment of the present invention.

The engine control device 1 includes a four-cylinder engine 2 and an electronic control unit (hereinafter simply referred to as ECU) 3 that controls the engine 2. The engine 2 includes second to fourth combustion chambers 5, 6.7 having a similar configuration to the first combustion chamber 4 formed from a cylinder 4a and a piston 4b.

Each combustion chamber4. ,5.6.7 is the intake valve 8,9゜'1
0.11 through intake port 12.13°14.1 respectively
It is connected to 5. Each intake boat 12゜13.14.1
A surge tank 16 for absorbing pulsation of intake air is provided upstream of the surge tank 5, and thrower valves 1 to 18 are provided inside the intake pipe 17 upstream of the surge tank 16. The throttle valve 18 is driven by a motor 19. The motor 19 responds to commands from the ECU 3.
The opening degree of the throttle valve 18 is changed to adjust the amount of intake air flowing through the intake pipe 17. The intake pipe 17 also has a bypass passage 2 which bypasses the valve 1B.
0 is provided in the bypass passage 20, and the idle speed controller 1 to roll valve (hereinafter simply referred to as 15CV) are provided.

) 21 is interposed. 15CV21 opens and closes in response to commands from the ECU 3 to adjust the amount of intake air flowing through the bypass path 20.

The engine 2 also operates in conjunction with an igniter 22 equipped with an ignition coil that outputs the high voltage necessary for ignition, and a crankshaft 23 to distribute and supply the high voltage generated by the igniter 22 to spark plugs (not shown) of each cylinder. It has a distribution network of 1-24.

The engine control device 1 has a surge tank 16 as a detector.
The intake pressure sensor +j3 is installed to detect the intake air pressure.
1. Cam shirt 1 to 1/2 of distributor 24
A rotation speed sensor 32 that outputs a rotation angle signal every four rotations, that is, every integer multiple of the crank angle 0° to 30°, a throttle position sensor 33 that detects the opening degrees of the thrower 1 to the valve 18, and an accelerator. An accelerator operation amount sensor 34 is provided to detect the amount of operation of the pedal 3/1a.

The detection signals of each sensor mentioned above are input to the ECU3, and the
U3 controls engine 2. F CLJ 3 is CP
It is configured as a logic wave line circuit centering on U3a, ROM3b, and RAM3c, and is connected to the input section 3e via a digital bus 3d.
, and are connected to the output section 3f to perform input/output with the outside.

In addition, as described later, the actual load i calculated by E CU 3
A signal corresponding to the torque estimated value and a signal corresponding to the upper limit load torque stored in the ECLJ 3 at which the idle state is reached are outputted from the output section 3f and inputted to the comparator 41. When the actual load 1~lux estimated value exceeds the upper limit load 1~lux for the idle state, the comparator 41
outputs a high level signal to the amplifier 42. On the other hand, when the throttle valve 18 is in an idle state in which it is fully open, the throttle position sensor 33 outputs an idle signal to the amplifier 42. Therefore, when the engine 2 is in the idle state and the estimated actual load torque exceeds the upper limit load torque for the idle state, the amplifier 42 is activated and the warning light 43 is turned on.

In this way, the engine control device 1 has a circuit that performs self-diagnosis of the engine 2 based on the estimated value of the actual load 1 to torque in the idle state.

The ECU 3 drives the motor 19 and l5CV 21 based on the detection results manually inputted from the intake pressure sensor 31, the rotational speed sensor 32, and the accelerator operation amount sensor 34 in accordance with the program stored in advance in the ROM 3b.
Feedback control is performed using the rotation speed as the target rotation speed. Next, a control system used for this feedback control will be explained based on the block diagram of FIG.

Note that FIG. 3 is a diagram showing the control system, and does not show the hardware configuration. The control system not shown in FIG. 3 is actually realized as a discrete system by executing a series of programs shown in the flowchart (1-1) of FIG.

As shown in FIG. 3, observer P1 controls = 14
− Rotational speed N, intake air pressure P, of the target engine 2;
Control amount S′ related to the adjustment of the intake air amount of the engine 2
From, the load torque −1′ is estimated and the load torque estimated value −
1'.

The linear performance section P2 calculates the first feedback amount by multiplying the load torque estimated value T', the engine 20 rotational speed N, and the intake air pressure UP by an element related to each value of the optimal feedback gain [', which will be described later. is calculated.

The target rotational speed setting section P3 is for setting the target rotational speed Nr of the engine 2. In this embodiment, the idle rotation speed is a predetermined idle speed in the idle state,
In the normal running state, the rotational speed commanded by the automatic transmission control device or the detection result of the accelerator operation amount sensor 4) 34 becomes the target rotational speed Nr.

The successive addition unit P4 accumulates the deviation e between the target rotational speed Nr and the rotational speed N to calculate a successive addition value Σe.

The coefficient east line section P5 calculates the second feedback m by multiplying the sequential addition value Σe by an element -[ related to the sequential addition value Σe of the optimum feedback gain F' to be described later.

Control @S' is calculated by adding the first feedback amount and the second feedback amount.

On the other hand, the riding boundary section P6 calculates a multiplication value P-N obtained by multiplying the rotational speed N of the engine 2 and the intake air pressure P by the east line.

In the coefficient east line portion P7, the operation amount S for adjusting the intake air amount of the engine 2 is calculated by subtracting the coefficient from the multiplication value PN and the correction value from the control amount S'. The manipulated variable S is the effective cross-sectional area of the intake throttle of the engine 2. That is, the stubtle valve 18 and l5CV
This amount corresponds to the opening degree of 21.

The hardware configuration J5 of the engine control device 1 and the configuration of the control system realized by executing the program described later have been described above. Next, the construction of the dynamic physical E del of the engine 2, the setting of the observer P1, and the calculation of the optimal feedback gain [' will be explained.

First, a dynamic physical model of engine 2 is constructed. The equation of motion of the engine 2 in the operating state can be written as the following equation (3).

dN/d t= (1/I) ・r,'X (Pc
i-Pa) ・-signature z-=1 (dVci/dθ) ~ Tf-TΩ] ...(3) However, N is the rotational speed, soil is the time, ■ is the inertia of the rotating part of the engine, ) is the number of cylinders, Pci is the pressure in the first cylinder, Pa is atmospheric pressure, 0 is the crank angle, ci is i
The number cylinder volume, Tf is mechanical loss torque, and TQ is actual load torque.

On the other hand, the mass conservation of intake air that enters a cylinder during the intake stroke of the engine 2 can be described as shown in the following equation (/1).

dP/dt.

= (C2/V) ・ [3-m-]Σ ((
Kc /+J (KC-1))・P・ (dVCi/d↑>-qm)/
f(Ki / (Ki −1))・R1・−riF]・
...(4) Note that the terms with a book are O except for the intake stroke.

However, P is the intake air pressure, C is the speed of sound, S is the effective cross-sectional area of the intake throttle, m is the amount of intake air per unit area, KC is the air-fuel mixture specific heat ratio, qm is the cylinder wall heat transfer amount, and Ki is the intake air specific heat ratio. , R1 is the intake air gas constant, Ti is the intake air temperature IU
, ■ is the intake volume.

In the above equation (3), since the indicated torque is approximately proportional to the intake air pressure P, it can be approximated as shown in the following equation (5).

(1/I)-[Σ(Pc1-Pa)・(d Vci/
dθ)];” +1 − α1 ・P (5) In the above equation (4), if the cylinder pressure P Ci is below the critical pressure,
Since the amount of intake air is proportional to the effective cross-sectional area S of the intake throttle, it can be approximated as shown in the following equation (6).

(C2/V)-3-m=(Xl ・S-(6)
Furthermore, in the above equation (4), since the amount of intake air taken into the cylinder is proportional to the product of the rotational speed N of the engine 2 and the intake air pressure P, it can be approximated as shown in the following equation (7).

-(C2/V)-[Σ((Kc/(Kc-1))・
P・+s+ (dVci/dt)-qm)/((Ki / (Ki
-1))・R1−r+ )*]−α2・P−N
...(7) Note that the terms marked with a book are O except for the intake stroke.

The above equations (3), (
1) can be approximated as shown in the following equations (8) and (9).

...(8) dP/dt-C1・Stenα2・P-N ...(9
) By discretizing the above equations (8) and (9), and then approximating the mechanical loss 1 to f as proportional to the rotational speed N and modifying each constant term, in the case of limp ring for a certain period of time, The following equation (10) is the identification basic equation.

(11) is obtained.

N(K+1)-C1・N (K) ten α2・P(K) ten α
3・P(K)・N (K)...(11) Here, the actual load 1~luke α3・TΩ(K> and the constant term α4 are expressed by the following equation (1
2), convert it into load i·lux T'(K>).

C3·T' (K) - In addition, the operation amount, ie, the intake throttle effective cross-sectional area S (K>), is converted into the throttle control ff1S'(K>) using J: in the following equation (13).

S' (K) = S (K) + (C3/α2) ・P
(K) · N (K>...(13) In addition, each constant term of both formulas (10) and (11) written in - is identified by the least squares method.

Using the above equations (12>, (13), the above equations (10), (
11) is linearized, the following equation (14) becomes % equation % Here, assuming that the load torque T' (K) changes stepwise, and taking the difference △T' (K), the following equation (1
There is a relationship shown in 5).

ΔD'(K>-T'(K>-T' (K-1
>-〇 (15) Therefore, from the above equations (14) and (15), the equation of state shown in the following equation (16) is obtained.

Further, the output equation is determined as shown in the following equation (17).

In this way, the dynamic physical model of this embodiment or the above equation (1
6) and (17). This dynamic physical model is a linearized version of the nonlinear engine 2.

Next, β1 will be explained about the design method of the observer P1. Gopinos' design R1 method is known for designing observers. ] ``Fundamental System Theory'' (published above), etc., but in this embodiment, ff1Uit is used as the minimum dimension obliver in accordance with Ipinas's i'i-1 method.

The above equations (16) and (17) are converted into the following equation (18).

(19) X (K+1 > =P-X (K) 10 I u
(K)...(18) V(K)=T・X (K>...(1
9) However, u (K)・-3' (K) T-[011].

The dynamic physics expressed by the above equations (18) and (19) ′[
Dell's minimum dimension observer is expressed by the following equations (20) and (21>
It is determined as follows.

Z(K>=A-7(K-1>+[B-v(K-1)-1
-J・LJ(K-1> ...(20) However, ItJ-P-A-11J=It3・■ J-υ・G, and the absolute value of the eigenvalue of A is less than 1 in both cases. Define U so that

'' Based on the two notations (20>, (21)), in this example, the load torque estimated value T' (K) and the actual load torque estimated value -r-Q (K> are expressed as the following equations (22>, (23) >.

It can be found as (24).

7(K) 10, 1・Z(K-1>10.11・N(K~1>+0.93・P(K-1>...(22) D' (K)-/(K )-0,12・N (K)・・
・(24) Next, we will explain how to find the optimal feedback gain F'. For example, the method to find the optimal feedback gain E' is described in "Linear System Control Theory" by Katsuhisa Furuta (
1975> Since I am familiar with Shokodo et al., I will omit the detailed explanation here and only show the results. By introducing the deviation e (K), the system represented by the equation of state of equation (16) above is expanded to a one-bo system. Here, the Sumisoup-Bison design method is used. Deviation e (K
) can be written as the following equation (25).

e (K) −N (K) −Nr ・(
25) Assuming that the rotational speed Nr changes in a stepwise manner, and finding the difference Δe (K) of the deviation e (K>), a relationship as shown in the following equation (26) is derived.

Δe (K) −e (K)−e (K−1)−N (
K) −N (K−1> −(Nr (K>−Nr (K−1))−ΔN (
K) ...(26> Therefore, the deviation e
(K) can be written as the following equation (27) 3゜e (K)=e (K-'l)+ΔN(K) ・12
7> From the above equations (16) and (27), when the system expanded to the -Lieho system is expressed in terms of the difference value, the equation of state as shown in the following equation (28) is expressed as 1q.

The above equation (28) is regarded as the following equation (29).

δX(K-1> = lpa-δX(K)+Ga-δu (K>-(29)
In other words, the discrete quadratic evaluation function can be expressed as the following equation (30).

J−Σ[δX” (K)・Q・δX(K)g<Q 10δ1,1” (K) −1R−δu (K)] ・
(30) Here, select the weight parameter matrices Q and R to minimize the input δU(K
) is given by the following equation (31).

δu(K)-F'-δX(K> ・(31)
Therefore, the optimum feedback gain "' is determined as shown in the following equation (32).

F'--([+Ga''-M-Ga)-1-Ga
” -M-Pa ・ (32) However,
M is a fixed symmetric matrix that satisfies the discrete Rikatsuji equation shown in the following equation (33). 1-(Ga''-M-Pa)-(33)
As a result, the deviation ΔS' (K) of the controlled variable is calculated by the following formula (3
4).

ΔS' (K)- However, F'=[F f].

When the above equation (34) is integrated, the control amount s' (k) is determined as shown in the following equation (35).

...(35) The above describes the construction of the dynamic physical model of engine 2, the design of the minimum dimension observer, and the optimal feedback gain "'
As described above, each parameter in the observer, the optimum feedback gain E', etc. are calculated in advance, and the ECU 3 performs actual control using only the results.

Next, the engine control process executed by the E' CU 3 will be explained based on the flowchart of FIG. In the following explanation, the amount handled in the current process is indicated by a subscript (K).31 engine control processes are
3 is started.

First, in step 100, initialization processing is performed to clear the register inside the CPU 3a and to set initial values to the second feedback amount 1e and the variable 7(K) in the observer. In the following step 110, a process of inputting the target rotational speed Nr is performed. The process of step 110 functions as the target rotational speed setting section P3 shown in FIG.

Next, the process proceeds to step 120, where a process is performed in which the rotational speed N (K>) is inputted from the rotational speed sensor 32, and the intake air pressure P (K) is inputted from the intake pressure sensor 31, respectively.

In subsequent steps 130 and 140, the load torque estimated value T'
(K>). First, in step 130, a process is performed to calculate variable 7(K) in the observer as shown in the following equation (36).

Z(K)=0.1 ・7(K-1) →-0,11・N(K-1>−1-0,93・P(K-1>...(36) Next, step Proceeding to step 140, the load]·lux estimated value -M (K) is calculated using the result of step 130 as shown in the following equation (37).

△ T' (K) - Z (K) - 0,12・N (K)... (37) The processing of steps 130 and 140 is performed by the observer P in FIG.
Functions as 1. In the following step 150, the load torque estimated value T' (K) calculated in the above step 140 is
Then, a process is performed to calculate the estimated actual load torque value ΔTQ(K) as shown in the following equation (38).

TQ(K) Next, the process proceeds to step 160, where the load torque estimate calculated in step 140, i'(K>, the rotational speed N (K) detected in step 120 above, and the intake air pressure horn P (K> The first feedback amount is obtained by multiplying by the optimal feed parameter 31 = factor of F', and the second feedback amount is added to the first feedback amount to calculate the control amount S' (K) as follows. A calculation process as shown in equation (39) is performed.

S' (K) - [11・T' (K) 10F12・N(K) 10F13
・P(K>+ie -139>main step 160
The processing functions as the linear calculation unit P2 in FIG.

In the subsequent step 170, a process is performed to calculate the intake throttle effective cross-sectional area S (K), which is a manipulated variable, from the control amount S'(K> calculated in step 160) as shown in the following equation (40).

5(K)=S' (K)-(α3/α2)・P (K
)・N (K) ... (40) This step 1
70 is performed by the multiplication unit P6 and the coefficient multiplication unit P in FIG.
Functions as 7.

Next, the process proceeds to step 180, where a process is performed to calculate the deviation 0(K) between the target rotational speed Nr input in step 110 and the rotational speed N(K) inputted in step 120 as shown in the following equation (41). It is done.

e (K> =N (K)-Nr ・(
4,1) In the following step 190, the above step 180
The second feedback lie is calculated by adding the product of the deviation e (K> calculated in Processing is performed.

1e=ie+1'-e (K)...142
) This step 190 is performed by the sequential addition unit P4 in FIG.
and functions as a coefficient multiplier P5.

Next, the process proceeds to step 200, in which a drive signal corresponding to the manipulated variable S (K> calculated in step 170 above is outputted to the motor 19 or l5CV21 via the output section 3f, and the actual drive signal calculated in step 150 is Processing is performed to output a signal corresponding to the estimated load torque value TQ(K) to the second comparator 11 via the output section 3f. 33 = After performing the process of adding the value 1 to the subscript K and updating the subscript K, the process returns to step 110 again.

Thereafter, the engine control process proceeds to step 110.
210 is repeatedly executed.

A comparison between the actual load torque estimate TQ estimated by this embodiment configured as described above and the actual load torque of 1°Ω applied to the engine 2 is shown in FIG. 5, as shown by the broken line in the figure. When the actual load torque TΩ of 20 [Nm] was applied to engine 2 from time 14 [SeC] to time 17 [5eCJ], the estimated actual load torque lower Ω was obtained, as shown by the solid line in the figure. . When applying load 1/lux TQ (
Time 14 [near 5 ecl] and release (time 17 [5 ecl)
eC1), the actual load torque estimated value TΩ suitably matches the actual load torque 1Q. In this way, the actual load torque of 1 Ω, which is difficult to measure, can be estimated with high accuracy.

In addition, the actual load 1 to the estimated value Ω, which has a physical meaning, is calculated. Therefore, for example, in an idle state, the engine 2 can be self-diagnosed by comparing the actual load 1 to the estimated torque value Ω with a predetermined upper limit load torque. This has the remarkable effect of being able to quickly detect, for example, a case where the engine 2 overheats and the friction between the piston and the cylinder increases due to burnout.

Furthermore, since the value T', the rotational speed N, and the intake air pressure P are used as state variables for estimating the load I/lux that has a physical meaning, and feedback control is performed using the optimal feedback gain, the rotation of the engine 2 is Control characteristics such as responsiveness and followability in speed control can be significantly improved.

Further, due to the above effect, for example, in the idle state, the idle rotational speed can be stabilized by suitable adjustment of l5CV2'l. On the other hand, when driving at a constant speed, the throttle valve opening is controlled through appropriate control of Tanabata 19, so impact vibrations such as the so-called acceleration/deceleration zapping phenomenon do not occur, which improves the ride comfort of the vehicle. It also improves.

Each of the effects described above is caused by constructing a dynamic physical model that is suitably linearized to suit the dynamic behavior of engine 2, which has nonlinearity.

Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and it goes without saying that it can be implemented in various forms without departing from the gist of the present invention. .

Effects of the Invention As detailed above, according to the load torque estimating device for an internal combustion engine of the present invention, a dynamic physical model that is linearized without impairing the dynamic characteristics of the internal combustion engine, which has nonlinearity, is constructed. This method has an excellent effect in that it is possible to accurately estimate the load 1 to luke, which is difficult to measure, based on a dynamic physical model that is well suited to the internal combustion engine that is the controlled object.

In addition, since it is possible to estimate the load 1 to torque that has a physical meaning, for example, in feedback control of an internal combustion engine in which the load torque is used as a state variable quantity and the control quantity is calculated from the state variable quantity using the optimum feedback gain. Improves responsiveness and followability.

Since the load torque, which is a physical quantity that is difficult to measure, is roughly estimated, the estimated load 1 to l can be effectively used for many purposes, such as performing self-diagnosis of the internal combustion engine based on the value of the load torque. It becomes possible to do so.

[Brief explanation of the drawing]

Fig. 1 is a basic configuration diagram conceptually illustrating the contents of the present invention, Fig. 2 is a system configuration diagram of an embodiment of the present invention, Fig. 3 is a block diagram similarly showing the control system, and Fig. 4 is a Similarly, FIG. 5 is a flowchart showing the control, and a graph showing a comparison between the actual load 1 to torque estimated value and the actual load torque. Ml...Internal combustion engine M2...Rotational speed detection means M3...Intake air pressure detection means M4...Controlled amount calculation means M5...Load torque calculation means 1...Engine control device-37=2 ...Engine 3...Electronic control unit (ECU) 3a...CPU 31...Intake pressure sensor 32...Rotational speed sensor

Claims (1)

[Scope of Claims] 1. Approximate rotational speed fluctuations of an internal combustion engine per predetermined time by a linear combination of at least the intake air pressure and load torque of the internal combustion engine, and approximate the fluctuations of intake air pressure of the internal combustion engine per predetermined time. An internal combustion engine that estimates the load torque of the internal combustion engine in accordance with a dynamic physical model of the internal combustion engine that is approximated by a linear combination of at least the product of intake air pressure and rotational speed and the intake air amount of the internal combustion engine. An engine load torque estimating device comprising: rotation speed detection means for detecting the rotation speed of the internal combustion engine; intake air pressure detection means for detecting the intake air pressure of the internal combustion engine; control amount calculation means for calculating a control amount involved in adjustment; and parameters set based on a dynamic physical model of the internal combustion engine to determine the rotational speed detected by the rotational speed detection means and the intake air. load torque calculation means for calculating the load torque of the internal combustion engine from the intake air pressure detected by the pressure detection means and the control amount calculated by the control amount calculation means; Device.