JPS611853A - Control device of internal-combustion engine - Google Patents

Abstract

PURPOSE:To obtain the maximum torque, by providing an arithmetic means, which outputs an ignition timing control signal so that a crank angle is set to a predetermined degree, and an ignition means which performs ignition in accordance with the ignition timing control signal. CONSTITUTION:A pressure detecting means 51 detects the pressure in a cylinder. A crank angle detecting means 52 detects a crank angle. An arithmetic means 53 outputs an air-fuel ratio control signal and an ignition timing control signal from a signal of the means 51 and 52. A mixture quantity regulating means 54 controls a mixture supplied to an engine. An ignition means 55 performs ignition in accordance with the ignition timing control signal. In this way, the maximum torque is obtained by enabling the optimum air-fuel ratio and the optimum ignition timing to be continually realized.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a device for controlling the air-fuel ratio and ignition timing of an air-fuel mixture supplied to an internal combustion engine.

[Prior art]

FIG. 2 is an example diagram of a conventional fuel control device.

In Figure 2, 1 is an air cleaner, 2 is an air flow meter that measures the amount of intake air, 3 is a throttle valve, 4 is an intake manifold, 5 is a cylinder, 6 is a water temperature sensor that detects the engine cooling water temperature, and 7 is an engine cooling water temperature sensor. A crank angle sensor detects the rotation angle of the crankshaft, 8 is an exhaust manifold,
9 is an exhaust sensor that detects the concentration of exhaust gas components (for example, oxygen concentration); 10 is a fuel injection valve; 11 is a spark plug; 12
is the control device.

The crank angle sensor 7 is connected, for example, to each crank angle reference position (every 180° for a 4-cylinder engine, 120° for a 6-cylinder engine).
A reference position pulse is output for each unit angle (for example, every 2 degrees), and a unit angle pulse is output for each unit angle (for example, every 2 degrees).

In the control device 12, the crank angle at that time can be determined by counting the number of unit angle pulses after this reference position pulse is input.

Furthermore, the rotational speed of the engine can be determined by measuring the frequency or period of the unit angular pulse.
- In the example of FIG. 2, a case is illustrated in which a crank angle sensor is provided within the distributor.

The control device 12 includes, for example, a CPU, RA, M, and ROM.

It is composed of a microcomputer consisting of an input/output interface, etc., and includes an intake air amount signal S1 given from the air flow meter 2, a water temperature signal S2 given from the water temperature sensor 6, a crank angle signal S3 given from the crank angle sensor 7, and an exhaust sensor. Exhaust signal S given from 9
4, a battery voltage signal (not shown), a signal from a fully open throttle switch, etc. are input, calculations are performed according to these signals to calculate the amount of fuel to be injected to the engine, and an injection signal S5 is output.

This injection signal S5 causes the fuel injection valve 10 to operate, supplying a predetermined amount of fuel to the engine.

The calculation of the fuel injection amount Ti in the control device 12 is performed, for example, using the following equation (for example, described in the Nissan Technical Manual 1979 E CC'S L Series Engine).

Ti=TpX(1+Ft+KMR/100)Xβ+Ts
...(1) In the above equation (1), Tp is the basic injection amount. For example, if the intake air amount is Q1, the engine rotation speed is N, and the constant is K, then Tp = -Q/N is required.

Further, Ft is a correction coefficient corresponding to the cooling water temperature of the engine, and for example, the value becomes larger as the cooling water temperature is lower.

Further, KMR is a correction coefficient at the time of high load, and is read out by table lookup from a value stored in advance in a data table as a value corresponding to the basic injection amount TP and rotational speed N, as shown in FIG. 4, for example. used.

Further, Ts is a correction coefficient based on the battery voltage, and is a coefficient for correcting fluctuations in the voltage that drives the fuel injection valve 10.

Further, β is a correction coefficient according to the exhaust signal S4 from the exhaust sensor 9, and by using this β, the air-fuel ratio of the air-fuel mixture is feedback-controlled to a predetermined value, for example, a value near the stoichiometric air-fuel ratio of 14.8. You can.

However, when feedback control is performed using this exhaust signal S4, the air-fuel ratio of the air-fuel mixture is always controlled to a constant value, so the above-mentioned correction based on cooling water temperature and correction due to high load are not required. It makes no sense.

Therefore, this feedback control using the exhaust signal S4 is performed only when the correction coefficient Ft based on water temperature and the correction coefficient KMR at high load are O.

The relationship between the above-mentioned correction calculations and sensors is shown in FIG. 3.

On the other hand, as an ignition timing control device for an internal combustion engine, there is one as shown in, for example, Japanese Patent Publication No. 59061 of 1982.

In the electronic ignition timing control device as described above, the optimum ignition advance value corresponding to the engine rotational speed N and the basic injection amount 'rp as shown in FIG. 5 is stored in advance as a data table. , at that time, a value corresponding to the rotational speed and basic injection amount is read out by table lookup, and the ignition timing is controlled to that value.

[Problem that the invention seeks to solve]

As mentioned above, conventional fuel control devices perform feedback control according to the exhaust sensor signal, but corrections due to high load conditions are determined by the basic injection amount and rotational speed, that is, the intake air amount and rotational speed. The correction is performed entirely under open-loop control.

Therefore, due to variations in air flow meters, fuel injection valves, etc., changes over time, etc., the air-fuel ratio at high loads may become the optimum air-fuel ratio (
L B T -Leanest Mixture fo
rBest Torque (note that this value is the air-fuel ratio that maximizes the generated torque, and is a different value from the air-fuel ratio feedback value based on the onion sensor signal mentioned above), and the torque decreases. There is a risk that the stability may deteriorate.

In addition, since the ignition timing control device uses an open-loop control method that reads data from a pre-stored data table and performs control, the optimum ignition timing (M B T-M
inimun+ 5park Advance for
There is a fear that the actual ignition timing may deviate from the best torque, resulting in problems such as a decrease in torque and the occurrence of knocking.

Further, the fuel control and ignition timing control described above are performed separately, and the two are not linked and controlled in a comprehensive manner. Therefore, optimal control was not necessarily performed.

The present invention aims to solve the problems of the prior art as described above.

[Means for solving problems]

In order to achieve the above object, the present invention detects the internal cylinder pressure of the engine and determines the air-fuel ratio of the engine from the detected value.
The ignition timing is set to MBT by feedback control so that the cylinder pressure is at a maximum, and by detecting the crank angle at which the cylinder pressure is maximum and controlling the ignition timing so that the crank angle is at a predetermined angle after top dead center. The engine is configured to operate at the LMBT point by controlling the feedback as shown in FIG.

Hereinafter, first, the principle for realizing LBT and MBT will be explained.

Fig. 6 is a diagram showing the relationship between crank angle and cylinder pressure, and Fig. 7 is a diagram showing the relationship between air-fuel ratio and generated torque, and the values under the condition that the throttle valve is fully open at a constant rotational speed (for example, 2000 rpm) are shown in Fig. 6. It shows.

As can be seen from Figure 6, the cylinder pressure is at compression top dead center (
10° to 20° after TDC), i.e. ATDCIO
It reaches its maximum at ˜206°.

Also, its maximum value changes depending on the air-fuel ratio A/F.
It reaches its maximum when F is around 13.

Further, as can be seen from FIG. 7, the torque generated by the engine reaches its maximum when the original air-fuel ratio is around 13, and this is called LBT.

Therefore, by performing feedback control to maximize the cylinder pressure, the air-fuel ratio under high load can always be controlled to the optimum air-fuel ratio LBT.

FIG. 8 is a diagram showing the relationship between the cylinder pressure and the crank angle when the ignition timing is changed, and shows the values under the condition that the throttle valve is fully open at a constant rotational speed (for example, 2000 rpm).

As can be seen from FIG. 8, the cylinder pressure curve changes depending on the ignition timing.

Then, the crank angle θ when the cylinder pressure is maximum
The largest torque is achieved when the ignition timing is controlled so that the ignition timing is at a predetermined angle (for example, 10° to 20°) after top dead center. The ignition timing at this time is called MBT.

FIG. 9 is a diagram showing the relationship between the crank angle Om at which the cylinder internal pressure is maximum and the ignition timing.

As can be seen from Figure 9, there is a nearly linear correspondence between 0m and the ignition timing, and by controlling the ignition timing,
The value of m can be set to any value.

Therefore, the generated torque can be maximized by controlling the ignition timing to set the value of θl to a value corresponding to MBT (for example, 15° after top dead center).

FIG. 10 is a diagram showing the relationship between ignition timing and generated torque.

As can be seen from FIG. 10, the generated torque is maximized when the ignition timing is controlled to the MBT point (for example, BTDC 20°).

By combining the air-fuel ratio control and the ignition timing control as described above, the characteristics shown in FIG. 11 are obtained as the conditions for maximizing the generated torque.

In the whistle diagram 11, the x mark is the LMBT point, that is, the point where both LBT and MBT are realized.

As can be seen from the above explanation, in order to operate the internal combustion engine at the LMBT point, the pressure inside the cylinder of the engine is detected, and based on that value, the air-fuel ratio of the engine is feedback-controlled to the LBT. The crank angle at which the pressure is maximum may be detected, and the ignition timing may be feedback-controlled so that the crank angle is at a predetermined angle after top dead center.

The predetermined crank angle θl for achieving the above MBT point is a value determined according to the engine's rod ratio, and is a value unique to that engine, and is generally 10° to 20° after top dead center.
', for example, a value of 15 degrees after top dead center.

The connecting rod ratio is the ratio between the length of the connecting rod and the radius of rotation of the crankshaft (172 of the stroke), and when the length of the connecting rod is L and the radius of rotation of the crankshaft is r, Rod ratio λ=L
/ r.

Next, FIG. 1 is a block diagram showing the functions of the present invention.

First, in FIG. 1(A), reference numeral 51 denotes pressure detection means for detecting the pressure inside the cylinder, for example, the pressure sensor 13 shown in FIG. 12 described later.

Further, 52 is a crank angle detection means for detecting the crank angle, and is, for example, the crank angle sensor 7 shown in FIG. 2 above.

Further, the calculation means 53 is composed of, for example, a microcomputer, and includes the pressure detection means 51 and the crank angle detection means 5.
The cylinder pressure Pmbt at the first predetermined crank angle and the cylinder pressure Pt at the second predetermined crank angle within one ignition cycle are detected from the signal Pmbt/Pt. Calculate the ratio Pmbt/Pt
outputs an air-fuel ratio control signal that controls the air-fuel ratio to maximize the air-fuel ratio.

Further, the crank angle at which the cylinder pressure within one ignition cycle is maximum is detected from the signals from the pressure detection means 51 and the crank angle detection means 52, and the crank angle is determined at a predetermined angle after top dead center (for example, An ignition timing control signal is output to control the ignition timing so that the ignition timing becomes 15° ATDC.

Next, the air-fuel mixture adjusting means 54 controls the air-fuel mixture supplied to the engine in accordance with the air-fuel ratio control signal given from the arithmetic means 53 described above.

This air-fuel mixture adjusting means 54 includes, for example, the fuel injection valve 10 shown in FIG.
No. 2326) can be used.

Further, the ignition means 55 performs ignition at the ignition timing according to the ignition timing control signal given from the arithmetic means 53 described above.

As the ignition means 55, a so-called full transistor ignition device W (a device consisting of a power transistor switching circuit and an ignition coil) and the ignition plug 11 can be used.

Next, in FIG. 1(B), the calculation means 56 calculates the maximum value Pm of the cylinder internal pressure within one ignition cycle and the predetermined crank angle from the signals from the pressure detection means 51 and the crank angle detection means 52. The cylinder pressure Pt is detected, the ratio Pm/Pt between the two is calculated, and an air-fuel ratio control signal is output to control the air-fuel ratio so that the ratio Pm/Pt is maximized.

Further, the crank angle at which the cylinder pressure reaches the maximum value Pa is detected, and an ignition timing control signal is output for controlling the ignition timing so that the crank angle becomes a predetermined angle after top dead center. The other parts are the same as in (A) above.

Next, in FIG. 1(C), the calculation means 57 calculates the indicated average effective pressure Pi within one ignition cycle from the signals from the pressure detection means 51 and the crank angle detection means 52,
The cylinder pressure Pt at a predetermined crank angle is detected, the ratio Pi/Pt between the two is calculated, and an air-fuel ratio control signal is output to control the air-fuel ratio so that the ratio Pi/Pt is maximized.

Further, the crank angle at which the cylinder internal pressure within one ignition cycle is maximized is detected from the signals from the pressure detection means 51 and the crank angle detection means 52, and the crank angle is set at a predetermined angle after the top dead center. outputs an ignition timing control signal to control ignition timing.

The other parts are the same as in (A) above.

In addition, the indicated average effective pressure Pi is the cylinder internal pressure for each crank angle, P, and the crank angle is a predetermined angle (for example, 2 degrees).
When the change in stroke volume each time is ΔV and the stroke volume is V.

It is determined by Pi=Σ(pxΔV)/V.

In (A) above, the cylinder pressure Pmbt at the first predetermined crank angle (for example, ATDC 15°) is normalized by the cylinder pressure Pt at the second predetermined crank angle (for example, TDC). to control the air-fuel ratio, and (
In B), the air-fuel ratio is controlled according to the value obtained by normalizing the maximum cylinder pressure Pm with the cylinder pressure Pt at a predetermined crank angle (for example, TDC), and in (C), the indicated average effective The air-fuel ratio is controlled according to a value obtained by normalizing the pressure Pi with the cylinder pressure Pt at a predetermined crank angle (for example, TDC), and furthermore, the crank angle at which the cylinder pressure becomes maximum is detected. Since the ignition timing is controlled so that the crank angle is at a predetermined angle after top dead center (for example, ATDC 15°), it is possible to always control the air-fuel ratio and ignition timing to the LMBT point. Become.

Note that the air-fuel ratio control in the present invention is performed by a device that performs feedback control to adjust the air-fuel ratio to the optimum air-fuel ratio LBT;
In other words, since it is a device that controls to maximize the generated torque, when it is used in common with a device that performs feedback control to satisfy exhaust purification performance according to the output of the exhaust sensor as shown in FIG. In addition to the configuration described above, a device for detecting high load (eg, detected from throttle valve opening or suction negative pressure) may be provided, and the air-fuel ratio control device of the present invention may be configured to operate only during high load.

[Embodiments of the invention]

Hereinafter, the present invention will be described in detail based on Examples.

FIG. 12 is a diagram showing an embodiment of the present invention.

In FIG. 12, 13 is a pressure sensor that detects the pressure inside the cylinder.

This pressure sensor 13 is used in place of the washer of the spark plug 11, and extracts changes in cylinder pressure as an electrical signal.

The control device 15 is composed of a microcomputer, for example, and includes an intake air amount signal S1 given from the air flow meter 2, a water temperature signal S2 given from the water temperature sensor 6, and a crank angle signal given from the crank angle sensor 7. S31. Exhaust signal S4 given from exhaust sensor 9
and the pressure signal 86 given from the pressure sensor 13, and perform predetermined calculations to determine the injection signal S5 and the ignition signal S.
7, thereby controlling the fuel injection valve 10 and the ignition device 16. In addition, the same symbols as in FIG. 2 indicate the same parts.

Next, FIG. 13 is an example diagram of the pressure sensor 13, (
A) shows a front view, and (B) shows a sectional view.

In FIG. 13, 13A is a ring-shaped piezoelectric element, 1
3B is a ring-shaped negative electrode, and 1.3C is a positive electrode.

Further, FIG. 14 is a diagram showing how the pressure sensor 13 is mounted, and is mounted to the cylinder head 14 by being tightened by the spark plug 11.

Next, calculations within the control device 15 will be explained.

FIG. 15 is a block diagram showing an embodiment of the control system of the present invention.

In FIG. 15, air flow meter 2, water temperature sensor 6
, the respective signals of the pressure sensors 13 and the voltage signals of batch January 7 are applied to a multiplexer 18 in the control device 15.

Further, the signal from the crank angle sensor 7 is applied to a latch circuit 19, and depending on the output of this latch circuit 19, a multiplexer 18 is switched to selectively send each of the above signals to an AI converter 20.

Each signal converted into a digital signal by the AD converter 20 and the signal from the crank angle sensor 7 are sent to the CPU 21.
Calculations as shown in the flowchart described later are performed, and the injection signal (corresponding to the air-fuel ratio control signal described above) calculated as a result of the calculation is power amplified in the output circuit 23 and then sent to the fuel injection valve 1o.

Further, the ignition timing control signal calculated as the calculation result is converted into an ignition signal by the output circuit 24, and then sent to the ignition device 16.

Note that 22 is a memory, which is comprised of a RAM that temporarily stores data during calculations, and a ROM that stores calculation procedures and various data (KMR data table, etc.) in advance.

Next, the contents of the calculation will be explained in detail.

FIG. 16 is a flowchart showing an example of calculations within the control device 15.

First, in FIG. 16(A), at Pl, the rotational speed N of the engine is read from the signal of the crank angle sensor.

Next, in P2, the intake air amount Q is read from the signal of the air flow meter.

Next, in P3, -Q/N is calculated for the basic injection amount TP=.

Next, in P4, the ignition advance angle value ADV is looked up from the data table shown in FIG. 5 in accordance with the above determined N and TP.

Next, in P5, the cylinder internal pressure Pn at that time is measured from the signal of the pressure sensor and stored.

Next, at P6, the crank angle at that time is compression top dead center (T
DC).

If the answer is No at P6, immediately proceed to P9.

If YES in P6, go to Pl, measure and store the cylinder internal pressure Pt at TDC.

Next, in P8, the above measured Pt is set as the initial value of the maximum value Pa of the cylinder internal pressure.

Further, the crank angle θ at this time is assumed to be O.

Next, in P9, it is determined whether the current cylinder internal pressure Pn is greater than the maximum value pH of the cylinder internal pressures up to the previous time.

If NO at P9, go to pH immediately.

If YES in P9, the process goes to PIO and stores the current cylinder internal pressure Pn as a new maximum value Pm.

Further, the crank angle at that time, that is, the crank angle θ corresponding to the maximum value is set as n.

Next, for pH, it is determined whether the crank angle is greater than ATDC 90°.

If the pH value is YES, the period in which the maximum value of the cylinder pressure occurs within the explosion cycle has ended, so the process goes to the next Pl2.

If No in Pll, return to Pll again and repeat the above procedure.

At Pl2, the above maximum value Pm is stored.

Next, in FIG. 16(B), at Pl3, the ratio between the maximum value Pi and the cylinder internal pressure Pt at TDC is calculated and stored.

Note that the entire calculation in the flowchart of Fig. 16 is repeated once per ignition cycle, and the subscript n of (P m / P t) n in Pl3 indicates the value in the current calculation. It shows.

Next, in Pl4, the value in the current calculation above and (P
m/Pt)n-□, that is, the magnitude is compared with the value in the previous calculation.

If the value in the current calculation is larger at Pt4, the process goes to Pt5 and it is determined whether the rich flag is 1 or not.

This rich flag is 1 when the air-fuel ratio is rich, that is, rich, and is 0 when the air-fuel ratio is lean, that is, thin.

If YES at Pt5, go to Pl6 and set the air-fuel ratio correction coefficient α to α=α+Δα.

That is, in a state where the air-fuel ratio is enriched, Pa
If the value of /Pt is increasing, the air-fuel ratio is further changed toward richer.

If No at Pt5, go to Pt7 and set α to α=α−Δ
Let it be α.

In other words, when the air-fuel ratio is lean, Pa/Pt
is increasing, the air-fuel ratio is controlled to be leaner.

On the other hand, if Pl, 4 is NO, the process goes to Pt8, and it is determined whether the rich flag is 1 or not.

If YES at Pt8, the process goes to 5P19 and after setting the rich flag to 0, α=α−Δα is set at P2O.

In other words, if Pa/Pt is decreasing while enriching the air-fuel ratio, it is necessary to make the air-fuel ratio lean, so after setting the rich flag to 0 at Pt9, α is set by a fixed amount Δα at P2O. decrease only.

If No at Pt8, go to P21 and set the rich flag to 1, and then set α=α+Δα at P22.

That is, when the air-fuel ratio is made lean and Pa/Pt decreases, it is necessary to make the air-fuel ratio rich, so after setting the rich flag to 1, control is performed so that α is increased by Δα.

Next, in P23, the fuel injection amount Ti=Tp·α+Ts is calculated using the air-fuel ratio correction coefficient α calculated as described above and is output.

Note that TP uses the value obtained in P3 above, and Ts
is calculated from the separately read battery voltage.

Next, in P24, the crank angle θm when the cylinder internal pressure obtained in the PIO reaches the maximum value Pm is 15°.
Determine whether the value is greater than or not.

This value of 15'' is a value for realizing the above-mentioned MBT, and is a value determined by the continuous rod ratio of the engine in the range of <ATDCIO° to 20° as described above.

In this embodiment, the angle is set to 15 degrees as an example.

If No in P24, this indicates that the crank angle at which the cylinder pressure is maximum is smaller than ATDC15', that is, the ignition advance angle is ahead of MBT, so go to P25 and change ΔA from the ignition advance angle ADV. The value obtained by subtracting is the new ignition advance angle.

If YES in P24, it indicates that the crank angle θm at which the cylinder pressure is maximum is greater than ATDC15'', that is, the ignition advance angle is behind MBT, so P2
Go to step 6 and set the new ignition advance angle ADV to be ADV plus ΔA.

As mentioned above, in the calculation shown in Fig. 16, the actual maximum value of the cylinder internal pressure is determined, and the air-fuel ratio is controlled so that the value obtained by normalizing that value by the cylinder internal pressure Pt at compression top dead center becomes the maximum value. The ignition timing is also controlled so that the maximum crank angle is at a predetermined position after top dead center.

By controlling as above, the air-fuel ratio is always LBT.
The ignition timing is always controlled to MBT.

Therefore, by the above control, the LMB shown in FIG.
It can be controlled to always match the T point.

In addition, at Pl4 in FIG. 16(B), the maximum value Pm of the cylinder internal pressure and the cylinder internal pressure P at the compression top dead center are
When correcting the air-fuel ratio based on the comparison result between the current value and the previous value of the ratio Pm/Pt, if the difference between the previous and current values is not very large, for example, if it is less than a predetermined value, Pl5 The configuration may also be such that the air-fuel ratio is maintained as it is without performing the process from P22. By doing so, hunting of the air-fuel ratio near the LBT can be suppressed and controllability can be improved.

Also, when controlling the ignition timing based on the comparison result in P24, similarly to the above, if the difference in the comparison result is less than a predetermined value, the processing in P25 and P26 is not performed and the ignition timing is maintained in that state. If so configured, hunting near the MBT can be suppressed.

Next, FIG. 17 is a flowchart showing a second embodiment of the calculation according to the present invention.

First, in FIG. 17(A), from Pl to pH is the same as from Pl to pH in FIG. 16.

However, the difference is that P27 and P'28 are inserted between PIO and Pll.

That is, at P27, the crank angle at that time is ATDC.
Determine whether the angle is 15° or not, and if YES, AT at P28.
Measure and store the cylinder pressure Pmbt at 15° DC.

ATDC15' in P27 is a value determined by the engine's continuous rod ratio as described above, and is the crank angle at which the cylinder internal pressure is thought to reach its maximum value.

Next, in FIG. 17(B), at P29, the above P
The ratio between mbt and cylinder internal pressure Pt at TDC is calculated and stored.

Next, in P2O, the value in the current calculation in P29 is compared in magnitude with (Pmbt/Pt)nz, that is, the value in the previous calculation.

The calculations from P15 to P26 thereafter are the same as those in FIG. 16 above.

As mentioned above, in the calculation of FIG. 17, the value P at the crank angle at which the cylinder pressure is expected to reach its maximum value
The air-fuel ratio can be controlled so that the value obtained by normalizing mbt by the cylinder internal pressure Pt at the compression top dead center becomes the maximum value.

This makes it possible to achieve the optimum air-fuel ratio LBT.

Further, since the crank angle θm at which the cylinder pressure reaches its maximum value is controlled to be a predetermined value (for example, ATDC 15°), MBT can always be achieved.

Next, FIG. 18 is a flowchart of an embodiment showing the third calculation of the present invention.

First, in FIG. 18(A), steps P1 to PIO are the same as those in FIG. 16.

However, the difference is that P31 and P32 are inserted between P5 and P6.

That is, in P31, a change ΔV in stroke volume is calculated every time the crank angle changes by a predetermined angle (for example, 2 degrees).

Next, in P32, the indicated mean effective pressure PL is calculated.

This indicated average effective pressure PL is the value obtained by dividing the work done by the combustion gas on the piston during one cycle by the stroke volume, and the cylinder pressure at each crank angle is P, and the crank angle changes by a unit angle (for example, 2 degrees). When the change in stroke volume each time is ΔV and the stroke volume is V, PL=Σ(pxΔ
V)/V".

Also, P irl = P 1n-1+ΔV'P
Approximate calculation can also be performed using the formula for n.

In addition, in the above formula, Pin is Pi in this calculation.
, Ptn-4 is the value of PL in the previous calculation (2 degrees ago in terms of crank angle), and Pn is the value of P in the current calculation.

Next, after performing calculations from P6 to PLO, in P33 it is determined whether the crank angle at that time is the exhaust top dead center.

If NO at P33, this indicates that the combustion cycle has not yet ended, so the process returns to P1 and repeats the above procedure again.

If YES in P33, one combustion cycle has been completed, so the process goes to P34 in FIG. 18(B).

In P34, the ratio between the indicated average effective pressure Pi and the cylinder internal pressure Pt at TDC is calculated and stored.

Next, in P35, the current value and the previous value are compared in magnitude.

The calculations from P15 to P26 thereafter are the same as in the case of FIG. 16 above.

As mentioned above, in the calculation of FIG. 18, the air-fuel ratio is corrected so that the value obtained by normalizing the indicated mean effective pressure Pi by the cylinder internal pressure Pt at compression top dead center, which represents the engine load, becomes the maximum value. The optimum air-fuel ratio LBT
Conditions can be realized accurately.

Also, the crank angle 0I11 at which the cylinder internal pressure is maximum
Since the ignition timing is feedback-controlled so that it is at a predetermined position after top dead center, the ignition timing can always be controlled to the MBT point.

In the example shown in Fig. 12, only one cylinder is shown, but in the case of a multi-cylinder engine, the fuel injection amount is corrected for each cylinder according to the signal from the pressure sensor attached to each cylinder. It is possible to control the

Further, although a pressure sensor is attached to each cylinder to measure the cylinder pressure, it is also possible to correct fuel injection by performing the same injection in all cylinders.

It is also possible to provide a pressure sensor in only one of several cylinders and correct the same injection amount for all cylinders based on the output of the pressure sensor.

Further, in the explanation so far, only the case where a fuel injection valve is used as the air-fuel mixture metering device has been explained, but it is possible to perform similar control even when a carburetor is used.

〔Effect of the invention〕

As explained above, in the present invention, the pressure in the cylinder is detected using a pressure sensor, the maximum value of the cylinder pressure, the indicated mean effective pressure, etc. The air-fuel ratio is configured to be feedback-controlled so that the value normalized by the cylinder internal pressure at the angle becomes the maximum, and the crank angle at which the cylinder internal pressure 1 is maximum is detected, and the crank angular force 1 is
Since the ignition timing is configured to be controlled to a predetermined angle after top dead center, even if there are novelty of parts or changes in timing, the optimum air-fuel ratio LBT and optimum ignition timing M are always maintained.
BT can be realized and the highest torque can be obtained.

Therefore, there are excellent effects such as eliminating the risk of insufficient torque or unstable L operation.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing the functions of the present invention, Fig. 2 is an example of a conventional fuel control device, Fig. 3 is a diagram of the relationship between calculation contents and sensors in the device shown in Fig. Figure 5 is a characteristic diagram of the high load correction coefficient, Figure 5 is a characteristic diagram of firing advance angle, Figure 6 is a characteristic diagram of crank angle and cylinder pressure, Figure 7 is a characteristic diagram of air-fuel ratio and torque, Figure 8 is a characteristic diagram of the cylinder internal pressure and crank angle when the ignition timing is changed.
Figure 9 is a characteristic diagram of crank angle and ignition period at which internal pressure is at its maximum, Figure 10 is a characteristic diagram of ignition timing and output torque, and Figure 11 is a characteristic diagram of air-fuel ratio and ignition timing. FIG. 12 is a diagram showing an embodiment of the present invention, and FIG.
Fig. 14 is an example of a pressure sensor used in the present invention, Fig. 1
15 is a block diagram showing one embodiment of the control system of the present invention, and FIGS. 16 to 181 are flowchart embodiments showing the calculations of the present invention. Explanation of symbols 1... Air cleaner 2... Air flow meter 3... Throttle valve 4... Intake manifold 5... Cylinder 6... Water temperature sensor 7...
・Crank angle sensor 8...Exhaust manifold 9...
・Exhaust sensor 10...Fuel injection valve 11...
Spark plug 12...Control device 13...Pressure sensor 13A...Piezoelectric element 13B...Minus electrode 13G...Plus electrode 14...Cylinder head 15...Control device 16...Ignition device
17...Novette 18...Multiplexer 19...Latch circuit 20...AD converter
21...CPU22...Memory 2
3.24... Output circuit 51... Pressure detection means
52...Crank angle detection means 53...Calculation means
54... Air mixture regulating means 55... Ignition means
56...Arithmetic means'57...Arithmetic means

Claims (1)

[Scope of Claims] 1. A pressure detection means for detecting the cylinder internal pressure, a crank angle detection means for detecting the crank angle, and a signal from the pressure detection means and the crank angle detection means within one ignition cycle. Cylinder internal pressure Pmbt at the first predetermined crank angle
and the cylinder internal pressure Pt at the second predetermined crank angle, and calculate the ratio Pmbt/Pt between the two, and calculate the ratio Pmbt/Pt.
Outputting an air-fuel ratio control signal to control the air-fuel ratio so as to maximize t/Pt, and from signals from the pressure detecting means and the crank angle detecting means, the cylinder pressure within one ignition cycle is maximized. a calculation means for detecting a crank angle and outputting an ignition timing control signal for controlling the ignition timing so that the crank angle becomes a predetermined angle after top dead center; A control device for an internal combustion engine, comprising: an air-fuel mixture metering means for supplying a fuel mixture to the engine; and an ignition means for igniting at an ignition timing according to the ignition timing control signal. 2. The calculation means calculates the first predetermined crank angle from 10° to 2° after the compression top dead center, which is determined by the continuous rod ratio of the engine.
A value in the range of 0° is used, and compression top dead center is used as the second predetermined crank angle, and the predetermined crank angle after top dead center in the ignition timing control is determined by the engine's continuous rod ratio. 2. The control device for an internal combustion engine according to claim 1, wherein a value in a range of 10° to 20° after compression top dead center is used. 3. A pressure detection means for detecting the cylinder pressure, a crank angle detection means for detecting the crank angle, and the maximum value of the cylinder pressure within one ignition cycle from the signals from the pressure detection means and the crank angle detection means. Detecting Pm and the cylinder internal pressure Pt at a predetermined crank angle, calculating the ratio Pm/Pt between the two, and outputting an air-fuel ratio control signal for controlling the air-fuel ratio so as to maximize the ratio Pm/Pt; and a calculation means for detecting a crank angle at which the cylinder pressure reaches a maximum value Pm and outputting an ignition timing control signal for controlling the ignition timing so that the crank angle becomes a predetermined angle after top dead center; A control device for an internal combustion engine, comprising: an air-fuel mixture adjusting means for supplying an air-fuel mixture to the engine according to an air-fuel ratio control signal; and an ignition means for igniting at an ignition timing according to the ignition timing control signal. 4. A pressure detection means for detecting the cylinder internal pressure, a crank angle detection means for detecting the crank angle, and an indicated effective average pressure Pi within one ignition cycle from the signals of the pressure detection means and the crank angle detection means. calculate the cylinder internal pressure Pt at a predetermined crank angle, calculate the ratio Pi/Pt between the two, and output an air-fuel ratio control signal for controlling the air-fuel ratio so as to maximize the ratio Pi/Pt; The crank angle at which the cylinder internal pressure is maximum within one ignition cycle is detected from the signals from the pressure detection means and the crank angle detection means, and ignition is performed so that the crank angle becomes a predetermined angle after top dead center. a calculation means for outputting an ignition timing control signal for controlling the ignition timing; a mixture adjusting means for supplying the engine with an air-fuel mixture according to the above air-fuel ratio control signal; A control device for an internal combustion engine, comprising an ignition means for performing.