JPS6155349A - Control device for internal-combustion engine - Google Patents

Abstract

PURPOSE:To aim at a distinct improvement in torque and a reduction in fuel consumption, by installing an operational device, outputting an air-fuel ratio controlling signal and an ignition timing controlling signal from each signal out of a cylinder internal pressure detecting device, a crank angle detecting device and a load detecting device. CONSTITUTION:There are provided with a pressure detecting device (a), detecting cylinder internal pressure, a crank angle detecting device (b), detecting a crank angle and a load detecting device (c), detecting engine load. An operational device (d) outputs an air-fuel ratio controlling signal so as to make a ratio P/Tp between cylinder internal pressure data P and load Tp the maximum, and also outputs an ignition timing controlling signal so as to make a crank angle the specified angle. A mixture metering device (e) feeds an engine with an air- fuel mixture, while an ignition device (f) ignites at its ignition timing. Thus, the engine is operatable under conditions of the optimum air-fuel ratio and the optimum ignition timing, whereby torque improvement and economization in fuel consumption are promotable.

Description

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

C Conventional technology J FIG. 22 shows an example of a conventional internal combustion engine control device.

As shown in this figure, fuel is sucked and pressure-fed from a fuel tank 1 to a fuel pump 2, pulsation is suppressed by a fuel damper 3, dirt and moisture are removed by a fuel filter 4, and pressure is increased by a pressure regulator 5. The fuel is kept constant and supplied to the fuel injection valve 6. 7 is a cold start valve that injects fuel to improve starting performance in cold regions. Furthermore, the air that has passed through the air cleaner 8 is measured by an air flow meter 9, the flow rate is controlled by a throttle valve 10, and the air is measured by an air flow meter 9.
1, is mixed with fuel (mixture) by a fuel injection valve 6, and is sent into a cylinder 12. This air-fuel mixture is compressed in a cylinder 12 and ignited by a spark plug 13 at an appropriate time. The exhaust gas passes through the exhaust manifold 14 and a purification device (not shown) and is released into the atmosphere. 40 is the exhaust gas component concentration (for example.

This is an exhaust sensor that detects oxygen concentration.

15 is a water temperature sensor that detects the cooling water temperature of the engine, 16 is a crank angle sensor built into the distributor that detects the rotation angle of the engine's crankshaft, 17 is an ignition device, and 1 is an air-fuel ratio of the air-fuel mixture supplied to the engine and ignition. This is a control device that controls the timing.

For example, the crank angle sensor 1G is set at the reference position of the crank angle (every 180' for a 4-cylinder engine, 120' for a 6-cylinder engine).
A reference position pulse is output at every m angle (for example, every 2 degrees), and a unit angle pulse is output at every m angle (for example, every 2 degrees). Then, in the control device 18, by counting the number of unit angle pulses after this reference position pulse is input, the crank angle at that time can be known. Furthermore, the rotational speed of the engine can be determined by measuring the frequency or period of the unit angular pulse.

The control device I8 is constituted by a microcomputer consisting of, for example, cpυ, RAM, ROM, input/output interface, etc., and receives an intake air amount signal S1 given from the above-mentioned air flow meter 9, a water temperature signal S2 given from the water temperature sensor 15, etc. A crank angle signal S3 given from the crank angle sensor IB, an exhaust signal SIO given from the exhaust sensor 40, an eight-point voltage signal (not shown), a throttle fully closed switch signal, etc. are input, and calculations are performed according to these signals. The fuel injection amount' to be supplied to the engine or the opening time of the fuel injection valve 6 is calculated, and an injection signal S5 is output. This injection signal S5 causes the fuel injection valves 6 in each cylinder to operate simultaneously once per engine revolution, supplying a predetermined amount of fuel to the engine.

The calculation of the fuel injection amount (fuel injection time) T+ within one day by the control device described above is performed, for example, by the following formula (for example, described in Nissan Technical Manual 1i1179 ECC5L series engine).

Tp = TpX (1+ Ft◆KMR/+00) X
β+Ts...(1) In the above equation (1), T
P is the basic injection amount (base valve time).For example, Q is the amount of intake air per revolution, N is the engine rotation speed, and K is the constant.
In this case, it can be obtained by calculating TP = K - Q/N. Further, F is a correction coefficient corresponding to the engine cooling water temperature, and for example, as shown in FIG. 2, the lower the cooling water temperature, the larger the value.

Further, KMR is a correction coefficient at high load, and is table lookup from a value stored in advance in a data table as a value corresponding to the basic injection amount Tp and engine rotational speed N, as shown in Fig. 3, for example. Read and use by. Also, Ts is a correction coefficient depending on the battery voltage,
This is a coefficient for correcting fluctuations in the voltage that drives the fuel injection valve 6. For example, when the battery voltage is VB and the constants are a and b, it is calculated as T5 = a + b (14 - VB), and is shown in Fig. 4. As shown, the lower the battery voltage, the larger the value.

Further, β is a correction coefficient according to the exhaust signal S10 from the exhaust sensor 40, 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. I can do it.

However, when feedback control is performed using this exhaust signal SIO, the air-fuel ratio of the mixture is always controlled to a constant value, so the above corrections based on cooling water temperature and high load are meaningless. Therefore, the feedback control using this exhaust signal S10 is
Correction coefficient Ft due to water temperature and correction coefficient KM at high load
This is done only when R is O.

On the other hand, as an ignition timing control method for an internal combustion engine, there is a method as shown in, for example, Patent Publication No. 59081 of 1981. In such an electronic ignition timing control system, 1 is used, for example, as shown in FIGS. 5 and 6.
The optimum ignition advance value corresponding to the engine rotational speed N and basic injection amount Tp is stored in advance as a data table, and the value corresponding to the rotational speed and basic injection amount at that time is read out by table lookup. , outputs an ignition signal S8 to the ignition device 17 so as to control the ignition timing to that value,
It is configured to drive the spark plug 13.

[Problem to be solved by the invention J However, in such a conventional control device,
Feedback control is performed according to the signal from the exhaust sensor, but the correction due to high load conditions is determined by the basic injection amount and rotational speed, that is, the intake air amount and rotational speed. is completely open-loop controlled.

Therefore, due to variations in air flow meters, fuel injection valves, etc., changes over time, etc., the optimum air-fuel ratio (LBT...Leanest Mixture)
rat Be5tTorque, which is the air-fuel ratio that maximizes the generated torque, and is a different value from the feedback value of the air-fuel ratio by the exhaust senna signal), resulting in a decrease in torque or deterioration of stability. There was a risk that it would happen.

In addition, since the ignition timing control is an open-loop control method that reads the ignition timing from a pre-stored data table and controls it, the ignition timing is initially matched to account for variations in the engine body, changes over time, etc. Optimal ignition timing (MBT...Minimum 5park
There was a risk that the actual ignition timing would deviate from the Advance for Be5t Torque, resulting in a decrease in torque and the occurrence of knocking.

Moreover, the above-mentioned fuel control and ignition timing control are each performed separately, and the two are not linked and controlled comprehensively. 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 the Problems] In order to achieve the above-mentioned object, the present invention detects the internal cylinder pressure and load of the engine, and calculates the internal pressure of the engine from a value obtained by normalizing the internal cylinder pressure value with the load value. The ignition is controlled by feedback control so that the air-fuel ratio becomes LBT, and by detecting the crank angle at which the cylinder internal pressure is maximum, and controlling the ignition timing so that the crank angle is at a predetermined angle after top dead center. By performing feedback control to set the timing to MBT, the engine is configured to operate at the LMBT (air-fuel ratio and ignition timing for maximizing generated torque) point.

Below, first, the principles for realizing LBT and MBT will be explained.

Figure 7 shows the relationship between crank angle and cylinder pressure,
Further, FIG. 8 shows the relationship between the air-fuel ratio and the generated torque, 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. 7, under the ignition timing condition (MBT) that provides i bulk h torque, the cylinder pressure is
10'~20° after DC:), i.e. ATDC1O
It reaches its maximum between 20° and 20°. Also, its maximum value is
It changes according to the air-fuel ratio A/F, and becomes maximum when A/F is around 13. Also, as can be seen from Figure 8, the torque generated by the engine is at its maximum when the air-fuel ratio is around 13, and this is
T is calling. 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. 9 shows the relationship between cylinder pressure and crank angle when the ignition timing is changed.
The values are shown 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. 9, the cylinder pressure curve changes depending on the ignition timing. Then, the crank angle Orn when the cylinder internal pressure is maximum is a predetermined angle after top dead center (for example, IQ0 to 20
The torque is greatest when the ignition time is controlled so that the The ignition timing at this time is called MBT.

FIG. 10 shows the relationship between the crank angle θm and the ignition timing at which the above-mentioned cylinder internal pressure becomes maximum. As can be seen from FIG. 10, there is a nearly linear correspondence between 0 m and the ignition timing, and by controlling the ignition timing, the value of θ□ can be set to any value. Therefore, by controlling the ignition timing, θ. If the value of is controlled to be a value at a point corresponding to BT (for example, 15 degrees after compression top dead center), the generated torque can be maximized. - Figure 11 shows the relationship between ignition timing and generated torque. As can be seen from FIG. 11, the generated torque is maximized when the ignition timing is controlled to 881 points (for example, BTp[]C20').

As described above, by combining the control of the air-fuel ratio and the itJ+ control of the ignition timing, the characteristics shown in FIG. 12 are obtained as conditions for maximizing the generated torque. In FIG. 12, the X mark is the LMBT point, that is, the point where both LBT and MBT are realized.

In this way, the maximum value of the cylinder internal pressure varies depending on the air-fuel ratio and ignition timing, but also varies depending on the load condition of one engine.

That is, as the load increases, the maximum value of the cylinder internal pressure also increases. Therefore, in order to operate the internal combustion engine accurately above the LMBT point, the cylinder pressure and load of the engine are detected by respective sensors, the detected cylinder pressure value is normalized by the load value, and the normalized value is Based on the value, feedback control is performed to set the engine air-fuel ratio to LBT, and the crank angle at which the cylinder pressure is maximum is detected.
It turns out that it is sufficient to perform feedback control on the ignition timing so that the crank angle is at a predetermined angle after top dead center.

The predetermined crank angle θm for achieving the above-mentioned 881 points is a value determined according to the engine's continuous rod ratio, and is a value unique to that engine, and is generally 10° to 20° after top dead center.
For example, the value is 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 (l/2 of the stroke).If the length of the connecting rod is divided by the radius of rotation of the crankshaft as r, then The rod ratio λ=L/r.

Next, FIG. 1 is a block diagram showing the constituent elements of the present invention. In FIG. 1, a is a pressure detection means for detecting the pressure inside the cylinder, for example, the pressure sensor 1 in FIG. 13, which will be described later.
It is 9. Further, b is a crank angle detection means for detecting the crank angle, and is, for example, the crank angle sensor 16 shown in FIG. 22 described above.

Further, C is a load detection means for detecting the load of the engine 1, for example, the air flow meter 9 shown in FIG. 22 described above, the intake pipe pressure sensor 2o shown in FIG. This is a throttle valve opening sensor (not shown) that detects the opening degree of the throttle valve.

Further, d is a calculating means, for example, composed of a microcomputer, and represents the cylinder pressure within one ignition cycle from the signals from the pressure detecting means a, the crank angle detecting means and the load detecting means C. Calculates the value P and the value T corresponding to the engine load, then calculates the ratio P/T of the two, and generates an air-fuel ratio control signal that controls the air-fuel ratio so that the ratio P/T is maximized. Output. The basic injection amount Tp can be used as the above-mentioned load value T. Further, the pressure value P is 1, for example, at a predetermined crank angle (for example, ATDG 15°
), the maximum value Pm of the cylinder internal pressure, or the indicated mean effective pressure Pi.

Further, the calculation means d detects the crank angle at which the cylinder internal pressure within one ignition cycle is maximum from the signals from the pressure detection means a and the crank angle detection means, Predetermined angle (for example, ATDC 15°)
An ignition timing control signal is output to control the ignition timing so that the following occurs.

Further, e is an air-fuel mixture adjusting means, which controls the air-fuel mixture supplied to the engine in accordance with the air-fuel ratio control signal given from the above-mentioned calculation means d. As the air-fuel mixture adjusting means e, for example, the fuel injection valve 6 shown in FIG. I can do it.

Further, f is an ignition means, which performs ignition at an ignition timing according to an ignition timing control signal given from the above-mentioned calculation means d. and an ignition coil) and a spark plug 13 can be used.

In addition, the above-mentioned indicated average effective pressure Pi is expressed as follows: Pn is the cylinder pressure of each crank angle signal, Δ■ is the change in stroke volume every time the crank angle changes by a predetermined angle (for example, 2 degrees), and V is the stroke volume. In this case, Pl−Σ(p, xΔV)/
It is determined by V. Here, since V is constant, Pt-P
Approximate calculation can be performed using the formula i+ΔvII Pn.

[Operation of the invention] In the present invention, a predetermined crank angle (for example, ATDG 15°
) is the value obtained by normalizing the cylinder internal pressure P+nb7 by the load Tp, or the value obtained by normalizing the maximum value Pm of the cylinder pressure by the load Tp, or the indicated average effective pressure P[ by the load element p
The air-fuel ratio is controlled according to the value normalized by , and the crank angle at which the cylinder pressure is at its maximum is detected, and the crank angle is set at a predetermined angle after compression top dead center (
For example, the ignition timing is controlled so that the air-fuel ratio and ignition timing are always at LM.
It becomes possible to control to point B.

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 the generated torque to the maximum, if it is used in common with a device that performs feedback control to satisfy exhaust purification performance according to the output of an exhaust sensor, the air conditioner of the present invention may be used only under high load. It may be configured to perform a fuel ratio control device.

[Embodiments of the invention] Hereinafter, the present invention will be described in detail based on Examples.

FIG. 13 shows an embodiment of the present invention. In FIG. 13, 19 is a pressure sensor that detects the pressure inside the cylinder.

This pressure sensor 19 is a voltage element formed into a washer shape, and is used in place of the washer of the spark plug 13, and extracts changes in cylinder pressure as an electrical signal.

The control device 21 is composed of, for example, a microcomputer, and also includes an intake air amount signal S1 given from the air flow meter 9, a water temperature signal S2 given from the water temperature sensor 15, and so on. The crank angle signal S3 given from the crank angle sensor 7 and the pressure signal 84 given from the pressure sensor 19 are input, and predetermined calculations are performed to output an injection signal S5 and an ignition signal S8. and the ignition device 17. In addition, the same symbols as in FIG. 22 indicate the same parts.

FIG. 14 shows an example of the above-mentioned pressure sensor 19, (A)
In FIG. 14, 18A is a ring-shaped piezoelectric element, 19B is a ring-shaped negative electrode, and 19C is a positive electrode.

Further, FIG. 15 shows the state in which the above-mentioned pressure sensor 19 is attached, and the pressure sensor 13 is attached to the cylinder head 22 by being tightened by the spark plug 13 as shown in this figure. This pressure sensor 19 generates an output proportional to the cylinder pressure, and outputs the cylinder pressure values as shown in FIGS. 7 and 9 described above.

Next, arithmetic processing within the control device 21 will be explained.

FIG. 18 shows an example of the configuration of the control system of the present invention.

i In Figure 16, air flow meter 9, water temperature sensor 15. The respective signals S1 and S2 of the pressure sensor 19
, S4 and the voltage signal Ve of the battery 23 are connected to the control device 21.
to multiplexer 24 within. Further, the signal S3 of the crank angle sensor IB is given to the latch circuit 25, and the output of the latch circuit 25 causes the multiplexer 2
4 inputs and selectively send each signal to an AD converter (
Analog fist digital converter) 26.

All weird! ! Each signal converted into a digital signal by the converter 28 and the signal from the crank angle sensor 1B are sent to the input circuit 2.
7 to the CPU (central processing unit) 28, where the arithmetic processing shown in the flowchart described later is performed.
The injection signal S5 (corresponding to the above-mentioned air-fuel ratio control signal) calculated as a result of the calculation is power amplified in the output circuit 30 and then sent to the fuel injection valve 6. Further, the ignition timing control signal calculated as the calculation result in the CPO 28 is converted into an ignition signal S8 by the output circuit 30, and then sent to the first ignition device 17.

Note that 29 is a memory, which includes a RAM (random access memory) that temporarily stores data during the calculation of the CPO 28, and a ROM that stores calculation procedures and various data (such as the above-mentioned KMR data table) in advance. (read-only memory), etc.

Next, the contents of the calculation according to the present invention will be explained in detail.

FIG. 17 is a flowchart showing an example of calculations within the control device 21. Here Pi, P2゜P3・
...indicates the steps of the processing procedure. First, Fig. 17 (A
), the engine rotational speed N is read from the signal S3 of the crank angle sensor 18, the intake air amount Q is read from the signal St of the air flow meter 9 (Pi), and then the basic injection is determined from the read N and Q. Quantity Tp = to -Q/N (
(where K is a constant) is calculated (P2).

Next, from the data table as shown in Figure 5, N and T
A table lookup is performed for the ignition advance value ADV corresponding to p (P3).

Next, the crank angle is read from the crank angle sensor 1B (P4), and then the crank angle at that time is the compression top dead center (T
OO) (P5). If NO (negative determination) in P5, the cylinder internal pressure Pn at that time is measured from the pressure signal S4 of the pressure sensor 18, and then stored (P5).
8), immediately go to p9. If YES (affirmative determination) in P5, the cylinder internal pressure Pt at TDC is measured and stored (p6), and the next measured pt is set as the initial value of the maximum value Pm of the cylinder internal pressure (P7).

Next, in p9, it is determined whether the current cylinder internal pressure Pn is greater than the maximum value pm of the cylinder internal pressures up to the previous time. If NO at P9, go to Pi2 immediately, p9
In the case of YES, the process proceeds to PIO and stores the current cylinder internal pressure Pn as a new maximum value P□ of the cylinder internal pressure. Further, the crank angle at that time is stored as the crank angle θ□ when the cylinder pressure is at its maximum (pH).

Next, at Pi2, it is determined whether the crank angle is greater than 40° ATDC (after compression top dead center). If YES in Pi2, the period in which the maximum value of the cylinder pressure occurs within the explosion cycle has ended (see Figures 7 and 9).
, Go to next Pi3 <, If NO in Pi2, go to P again
Return to step 4 and repeat the above steps.

Next, in FIG. 17(B), in PlB, the above p
ATDC + 5° (or A
TDC: 15°±β). This ATD015°
The value is the value for realizing the above-mentioned MBT,
As mentioned above, AT [IC is a value determined by the engine's continuous rod ratio in the range of 10° to 20°. In the case of this embodiment, it is set to 15° as an example (see Figure 10). .

Om at PlB is ATDC15° (or ATDC15
°±β, where β is a small angle. ), it indicates that the ignition advance angle is corrected (10th
(see figure), there is no need for lead angle correction, and it immediately goes to Pi6 8th line,
Crank angle θ1 at which the cylinder pressure is maximum at PlB
If it is determined that is smaller than ATDC15° (or ATD (:15°-β)), it indicates that the ignition advance angle is ahead of MBT (see Figure 10), PI3
The value obtained by subtracting ΔA from the ignition advance angle ADV is set as the new ignition advance angle ADV. PlB, the crank angle θ at which the cylinder internal pressure is maximum is ATD (: 15° (or ATD
If it is determined that the ignition advance angle is larger than C15°+β), it indicates that the ignition advance angle is delayed than the MBT (first
0), go to PI3 and set ΔA to ignition advance angle ADV.
The value added is the new ignition advance angle ADV.

Next, at 216, the maximum value Pm of the above-mentioned cylinder internal pressure is
and the basic fuel injection amount Tp obtained in 22 (Pm /T
p) Calculate and store n. Note that the entire calculation in the flowchart of FIG. 17 is repeated once every ignition cycle, and (Pm /Tp) of 21B.

The subscript n is 1. This indicates that it is the value for the current calculation. Furthermore, since Tp is a value corresponding to a change in load, (Pm/Tp)n corresponds to the maximum value pm of the cylinder internal pressure normalized by the load.

Next, in PI3, the value (Pm
/Tp) n and the value in the previous calculation (Pm/Tp
) Compare n-1 with 0 If the sizes of both are equal, there is no need to correct the air-fuel ratio, so immediately go to P2 <, P
If the value (Pm/Tp)n in the current calculation is larger in I3, it means that the air-fuel ratio correction direction is correct, so the process goes to PlB and determines whether the rich flag is 1 or not. This rich flag is l when the air-fuel ratio (A/l') is being corrected to make it richer, that is, to make the air-fuel mixture richer, and when it is being corrected to be leaner, that is, to make the air-fuel mixture leaner. It is O.

If YES at PlB, go to PlB and set the air-fuel ratio correction coefficient α to α=α+Δα. In other words, if the value of Pro/TP is increasing while the air-fuel ratio is enriched, the air-fuel ratio is further changed in the rich direction (see Figure 8). goes to P2O and sets the air-fuel ratio correction coefficient α to α=α−Δα. In other words, when the air-fuel ratio is lean, Pm/T
If p is increasing, the air-fuel ratio is controlled to be leaner (see FIG. 8). Through this procedure of PlB and P2O, the air-fuel ratio approaches LBT.

On the other hand, on Pi7, the value (Pm /Tp
) n is the value (Pm /Tp) in the previous calculation.

If it is smaller than -1, the process goes to P21 and it is determined whether the rich flag is 1 or not. If YES at P21, the process goes to P22, where the rich flag is set to 0, and then the coefficient α is set to α=α−Δα at P2O. In other words, when Pffl/Tp decreases while enriching the air-fuel ratio, it is necessary to lean the air-fuel ratio to achieve LBT, as shown in Figure 8, so after inverting the rich flag to O in P22. , P2O decreases the coefficient α by a constant grinding amount Δα. P
If NO in 21, go to P23, set the rich flag to 1, and then set α=α+Δα in PlB. In other words, when Pm/Tp decreases when the air-fuel ratio is lean, it is necessary to richen the air-fuel ratio to achieve LBT as shown in Fig. 8, so after inverting the rich flag to 1, PlB The coefficient α is controlled to be increased by a constant amount Δα.

Next, water temperature sensor 1 with the cold temperature correction coefficient ↑S read separately.
The battery voltage of the battery 23 is calculated from the water temperature signal S2 of No. 5 and the voltage correction coefficient TS is read separately (P24), and the high load correction coefficient according to the rotational speed N of one engine and the basic injection amount TP. Table lookup for KMR (P25), then.

Using the air-fuel ratio correction coefficient α, etc. calculated as described above, the fuel injection amount T1 is calculated and output according to the following equation (2) (
P2B).

T [Tp X (1+ Ft +KMR/100)
(2) The initial value of the air-fuel ratio correction coefficient α is set to 1 at the time of engine startup, then P2
7, for the calculation for the next explosion, the current (
Pm /Tp )n is stored as (Pm /Tp ) n-+, and the 0th cycle in which the current arithmetic processing ends starts from Pl by an interrupt.

As mentioned above, in the calculation of FIG. 17, the actual maximum value of the cylinder internal pressure is determined, and that value is set as
The air-fuel ratio is controlled so that the value normalized by P is the maximum,
The ignition timing is also controlled so that the maximum crank angle is at a predetermined position after top dead center. By controlling in this manner, the air-fuel ratio is always controlled to LOT, and the ignition timing is always controlled to MBT. Therefore, by the above-mentioned control, the engine can be controlled so as to always match the tJIBT point shown in the above-mentioned ER12 diagram.

Next, FIG. 18 is a flowchart showing a second embodiment of the calculation according to the present invention.

First, in FIG. 18(A), steps p1 to P4 are the same as those in FIG. 17(A) described above. After treatment of Pt,
The amount of change ΔV in stroke volume every time the crank angle changes by a predetermined angle (for example, 2 degrees) is calculated from the crank angle read in Pt (Pt-1).

The process from P5 to pH is the same as in FIG. 17(A) above, except that P7-1 is inserted between p7 and P9. In this P7-1, the indicated mean effective pressure Pi is reset to O.

If the result in P9 is NO, and if the PTT processing is completed, the process goes to pH-1 and the indicated mean effective pressure Pi is calculated. This indicated average effective pressure Pi is the value obtained by dividing the work done by the fuel gas on the piston during one cycle by the stroke volume, and the cylinder pressure at each crank angle is pn, and the crank angle changes by a unit angle (for example, 2 degrees). When the change in stroke volume for each stroke is ΔV, it can be approximately determined using the quadratic equation (3).

PI ”PI + ΔV −pn
-(3) In other words, the value obtained by integrating the cylinder internal pressure Pn and the amount of change in stroke volume ΔV in the current calculation and adding it to the value of Pi in the previous calculation (2 degrees earlier in terms of crank angle) is calculated as the current P[ shall be.

Next, check whether the crank angle read in Pt has reached just before compression top dead center, that is, BTDC (before compression top dead center).
It is determined whether the angle exceeds 10° (Pl2-1).

This BTDCIOo is the crank angle tentatively determined at the end of the 4th cycle, and may be, for example, BTDCG'.
If No in Pl2-1, return to Pt and repeat the above procedure.

If Pl2-1 is YES, 4 cycles (1 ignition cycle) have been completed, so Pl2-1 in Figure 1118 (B)
Steps from Pi3 to Pi5 in FIG. 18(B), which proceed to step 3, are the same as those in FIG. 17(B) described above.

In the next pte-t, by reversing the above pH-1 treatment, the indicated mean effective pressures PI and P2
The ratio to the basic fuel injection amount TP determined by (Pi/Tp)
Calculate and store n. The subscript n of (PI/Tp)Ω indicates the value in the calculation of the current ignition cycle.Next, in Pl7-1, the current value (PI
/Tp) n and previous value (P+ /Tp) n-+
Compare the size with.

The subsequent calculations of Pi8 to P2B are as shown in Figure 17 (
This is the same as case B). In P27-1, the current value (
Pi/Tp)n is stored as (Pt/Tp)n-+, and the current arithmetic processing is ended.

In this way, in the calculation shown in FIG. 18, the air-fuel ratio is controlled so that the value obtained by normalizing the indicated mean effective pressure Pi by Tp, which corresponds to the engine load, is the maximum, so the optimum air-fuel ratio The LBT condition can be realized more accurately. Further, since the ignition timing is feedback-controlled so that the crank angle θ□ at which the cylinder pressure is maximum is at a predetermined position after the top dead center, the ignition timing can always be controlled at 887 points.

19 to 2+ show an embodiment of the present invention using an intake pipe pressure sensor 20 as a load detection means for detecting the load of the engine. As shown in FIGS. 13 and 20, an air flow meter is used. Instead, an intake pipe pressure sensor 20 is provided in the intake manifold 11, and an intake pipe pressure signal S7 of this intake pipe pressure sensor 20 is input to the multiplexer 24 of the control device 21. Other points are shown in Figures 13 and 16 above.
It is similar to the figure. Further, in the calculation flowchart, as shown in FIG. 21(A), the intake pipe pressure pb is read from the engine rotational speed N and the signal S7 of the intake pipe pressure sensor 20 at Pl-1.

Next, in 22-1, the above read N and Pb
The basic injection amount Tp - IKII pb /N (where K is a constant) is calculated from. After that P3~P2? are similar to FIGS. 17(A) and 17(B) described above.

In the embodiments shown in FIGS. 13 and 19, only one cylinder 12 is shown, but in the case of a multi-cylinder engine, each cylinder is It is possible to correct and control the fuel injection amount for each cylinder. Further, a pressure sensor is attached to each cylinder to fix the cylinder pressure, but it is also possible to correct the fuel injection by performing the same injection in all cylinders. Further, it is also possible to provide a pressure sensor and a load sensor in only one of several cylinders, and correct the same injection amount for all cylinders based on the output of the 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.

[Effects of the Invention] As explained above, according to the present invention, the pressure inside the cylinder is detected using a pressure sensor, the maximum value of the cylinder internal pressure, the indicated average effective pressure, etc. are determined from the detected values, and the values are calculated. The air-fuel ratio is controlled by a feed bar so that the value normalized by the load is the maximum value, and the crank angle at which the cylinder pressure is maximum is detected, and that crank angle is set at top dead end. Since the ignition timing is configured to be feedback-controlled so that the ignition timing is at a predetermined angle after the ignition point, the optimum air-fuel ratio ( The engine can be operated under the conditions of LBT) and optimum ignition timing (MBT), improving torque and reducing fuel consumption. In particular, in the present invention, pressure values such as the indicated mean effective pressure are normalized by the engine load as described above, so the LB is extremely accurate compared to the conventional method.
There is an advantage that T control can be performed.

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

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the components and functions of the present invention, and FIG. 2 is a characteristic diagram of the water temperature increase correction coefficient. Figure 3 is a characteristic diagram of high load correction coefficient, Figure 4 is a characteristic diagram of battery voltage correction coefficient, Figures 5 and 6 are ignition advance angle characteristic diagram, and Figure 7 is a characteristic diagram of crank angle and cylinder pressure. Figure 8 is a characteristic diagram of air-fuel ratio and torque. Figure 9 is a characteristic diagram of cylinder pressure and crank angle when the ignition timing is changed. Figure 10 is a crank angle at which the cylinder pressure is maximum. Characteristic diagram of ignition timing and ignition timing. FIG. 11 is a characteristic diagram of ignition timing and output torque, and FIG. 12 is a characteristic diagram of torque according to air-fuel ratio and ignition timing. Fig. 13 is an internal configuration diagram showing an embodiment of the present invention, Fig. 14 (A) is a plan view showing an example of a pressure sensor used in the present invention, and Fig. 14 (B) is a diagram showing an example of the pressure sensor used in the present invention. FIG. 15 is a partially cutaway front view showing the installation state of the pressure sensor; FIG. 18 is a block diagram showing an embodiment of the control system of the present invention; FIG. 17(A), B) is a flowchart showing one embodiment of the calculation of the present invention. 18(A) and 18(B) are flowcharts showing another embodiment of the calculation of the present invention, FIG. 19 is an internal configuration diagram showing another embodiment of the present invention, and FIG. 20 is a control system of the present invention. 21(A) and 21(B) are flowcharts showing still another embodiment of the calculation of the present invention, and FIG. 22 shows an example of a conventional internal combustion engine control device. FIG. 1... Fuel tank, 2... Fuel pump, 3... Fuel damper, 4... Fuel filter, 510. Pressure regulator, 6... Fuel injection valve, 7... Cold start valve, 8... Air cleaner, 9... Air flow meter, lO... Throttle valve, 11... Intake manifold. 12...Cylinder, 13...Spark plug, 14...Exhaust manifold. I5...Water temperature sensor, 16...Crank angle sensor, 17...Ignition device, 18...Control device. 19...Pressure sensor. 20... Intake pipe pressure sensor, 21... Control device, 22... Cylinder head, 23... Battery. 24... Multiplexer, 25... Latch circuit, 26... AD converter, 27... Input circuit, 28... CPU. 29...Memory, 3G...Output circuit. 40...Exhaust sensor. Mercury (0C) Fig. 3 Engine rotation N, (rpm) Fig. 4 Fukuya MI voltage (VB) Fig. 5 Engine mouth speed vL and (rpm) Fig. 6 ■ Fig. 8 Fig. 10 Mo Fire season (8TDC') ψ Kano QLn■n■−■To~ −−〜 −

Claims (1)

[Claims] 1) Pressure detection means for detecting cylinder internal pressure, crank angle detection means for detecting a crank angle, load detection means for detecting engine load, and a signal of the pressure detection means and the crankshaft. A ratio P/Tp between specific cylinder pressure data P and load Tp within one ignition cycle is calculated from the signal of the angle detection means and the signal of the load detection means, and the ratio P/Tp is maximized. outputting an air-fuel ratio control signal for controlling the air-fuel ratio as shown in FIG. , a calculation means for outputting an ignition timing control signal for controlling ignition timing so that the crank angle is at a predetermined angle after compression top dead center; and an air-fuel mixture for supplying an air-fuel mixture to the engine according to the air-fuel ratio control signal. A control device for an internal combustion engine, comprising: a metering means; and an ignition means for igniting at an ignition timing according to the ignition timing control signal. 2) The cylinder pressure data P is the cylinder pressure Pmbt at a predetermined crank angle, the maximum value Pm of the cylinder pressure, or the indicated effective average pressure Pi, as set forth in claim 1. Control equipment for internal combustion engines. 3) The load pressure detection means is a sensor that detects intake air flow rate, a sensor that detects intake pipe pressure, or a sensor that detects throttle valve opening. 2. The control device for an internal combustion engine according to item 2. 4) A patent characterized in that, as the predetermined crank angle after compression top dead center in the ignition timing control, a value in the range of 10° to 20° after compression top dead center is used, which is determined by the continuous rod ratio of the engine. A control device for an internal combustion engine according to claim 1. 5) As the predetermined crank angle for the cylinder internal pressure Pmbt, a value in the range of 10° to 20° after the compression top dead center determined by the continuous rod ratio of the engine is used. A control device for an internal combustion engine as described in .