JPH09317522A - Engine control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To burn fuel in a lean-burning state and to improve fuel consumption by detecting an actual combustion ratio until a prescribed crank angle and comparing a detected combustion ratio with a target combustion ratio and controlling a fuel supply amount such that a fuel supply amount is increased (decreased) when the detected combustion ratio is smaller (larger) than the target combustion ratio. SOLUTION: When an engine is operated in a state of a middle/high engine speed where, in a controller 12, a throttle opening is a prescribed value or more and an engine speed is a prescribed value or more and the change ratio of the throttle opening is a prescribed value or less, a variable C is made 1. When the engine is operated in a transition state where the change ratio of the throttle opening is a prescribed value or more, the variable C is made 2 and, when the throttle opening, the engine is judged to be controlled in a lean- burning state and variable C is a prescribed value or less and the engine speed is in a prescribed range, the variable C is made 3. After the variable is set in these ways, a target combustion ratio corresponding to the engine speed and the load is determined by using map data and is compared with a detected combustion ratio to thereby control the injection amount of an injector.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling a 2-cycle spark ignition engine or a 4-cycle spark ignition engine.

[0002]

2. Description of the Related Art In a two-cycle spark ignition engine or a four-cycle spark ignition engine, for example, O
₂ sensors are arranged, the A / F value is calculated from the exhaust gas concentration, and the fuel supply amount so that the calculated value approaches the target value,
Alternatively, there is one that controls the air flow rate to reduce NOx.

There is another method in which the pressure in the combustion chamber is detected, the average effective pressure of the engine is calculated, and the ignition timing is feedback-controlled based on the calculated data.

[0004]

Based on this conventional technique, it is conceivable to carry out this feedback control in order to obtain stable lean combustion and low fuel consumption even in the low and medium load regions.

However, even if only the A / F value is brought close to the target value, the combustion state changes depending on the ignition timing, the output of the engine decreases and stable rotation cannot be obtained, or the output of the engine becomes high. The value becomes high.

Also, the average effective pressure of the engine is calculated,
Even if the ignition timing can be fed back based on the calculated data to increase the output of the engine, the NOx value becomes high when the combustion is rapid.

The present invention has been made in view of the above point, and the inventor has found that the combustion ratio up to a predetermined crank angle has a high correlation with the engine output and the exhaust emission, and reduces the exhaust emission. It is an object of the present invention to provide a method of controlling an engine that enables lean combustion while improving fuel efficiency.

[0008]

In order to solve the above-mentioned problems and to achieve the object, a method of controlling an engine according to a first aspect of the present invention is such that at least an initial value of a fuel supply amount according to a load is used. , Has the data of the initial value of the fuel supply amount set so that the lean air-fuel mixture is formed in the combustion chamber when the fuel is supplied to the engine, and the one or more combustion ratios at one or more predetermined crank angles. Is stored in the memory as map data of one or more target combustion ratios corresponding to at least one of the load and the engine speed, or one or more crank angles that reach one or more predetermined combustion ratios are Alternatively, one or a plurality of target crank angle map data corresponding to at least one of the engine speeds may be held in a memory, or one or a plurality of these map data may be stored. The actual combustion ratio up to the constant crank angle is detected, and based on the comparison between the detected combustion ratio and the target combustion ratio, the fuel supply amount is increased when the detected combustion ratio is smaller and the detected combustion ratio is larger. Then, the actual crank angle at which the fuel supply amount is reduced or when one or more of the predetermined combustion ratios is reached is detected, and the target crank angle is determined based on the comparison between the detected crank angle and the target crank angle. The fuel supply amount control is performed by increasing the fuel supply amount when the engine is advancing and decreasing the fuel supply amount when the detected value crank angle is advancing.

In this way, the actual combustion ratio up to one or more predetermined crank angles is detected, and based on the comparison between the detected combustion ratio and the target combustion ratio, the fuel supply amount when the detected combustion ratio is smaller Is increased to decrease the fuel supply amount when the detected combustion ratio is larger, or to detect the actual crank angle at which the one or more predetermined combustion ratios are reached,
Based on this comparison between the detected crank angle and the target crank angle, whether the fuel supply amount is increased when the target crank angle is ahead and the fuel supply amount is decreased when the detected value crank angle is ahead. By controlling either of the fuel supply amounts, exhaust combustion is reduced and lean combustion is enabled to improve fuel efficiency.

According to another aspect of the engine control method of the present invention, the target combustion ratio has a permissible range, and the first target combustion ratio is larger than the target combustion ratio in the map data and the first target combustion ratio is smaller than the target combustion ratio in the map data. 2 target combustion ratio is set, and when the detected combustion ratio is smaller than the second target combustion ratio, the fuel supply amount is increased, and the detected combustion ratio is the first
When the combustion amount is larger than the target combustion ratio, the fuel supply amount is reduced, and when the detected combustion ratio is between the first target combustion ratio and the second target combustion ratio, the fuel supply amount is not changed or the target crank angle is changed. Has a permissible width, and a first target crank angle that is ahead of the target crank angle in the map data and a second target crank angle that is later than the target crank angle in the map data are set, and detected from the first target crank angle. When the crank angle is ahead, the fuel supply amount is decreased, and when the detected value crank angle is behind the second target crank angle, the fuel supply amount is increased, and the detected crank angle is the first target crank angle. Is between the second target crank angle and the second target crank angle, the fuel supply amount is controlled so as not to change the fuel supply amount.

As described above, the fuel supply amount control is performed based on the target combustion ratio of the map data with the allowable range of the target combustion ratio and the target crank angle of the map data with the allowable range of the target crank angle. The fuel supply amount is controlled based on the combustion ratio up to a predetermined crank ratio or the crank angle that reaches the predetermined combustion ratio easily and accurately, and lean combustion is enabled and fuel consumption is improved while reducing exhaust emission.

According to the engine control method of the third aspect of the present invention, when the load is smaller than a predetermined value or the engine speed is smaller than the predetermined value, at least one of them is executed, and either fuel supply amount control is executed. It is characterized by that.

In this way, the fuel supply amount is controlled based on the load or the engine speed to stabilize the engine output.

According to a fourth aspect of the engine control method of the present invention, the initial value of the ignition timing corresponding to at least one of the load and the engine speed is stored as data, and one or more predetermined crank angles at one or more predetermined crank angles. The combustion ratio is retained in the memory as map data of one or more target combustion ratios corresponding to at least one of load and engine speed, or one or more crank angles that reach one or more predetermined combustion ratios are stored. , Is stored in a memory as map data of one or more target crank angles corresponding to at least one of load or engine speed, or on the other hand, the actual combustion ratio up to one or more predetermined crank angles is detected, Based on the comparison between the detected combustion ratio and the target combustion ratio, advance the ignition timing at which the detected combustion ratio becomes smaller The actual crank angle that delays the ignition timing when the combustion ratio is larger or reaches the one or more predetermined combustion ratios is detected, and the target crank angle is calculated based on the comparison between the detected crank angle and the target crank angle. The ignition timing control is performed by either advancing the ignition timing when the ignition timing is advancing, or delaying the ignition timing when the detection value crank angle is advancing.

In this way, the actual combustion ratio up to one or a plurality of predetermined crank angles is detected, and based on the comparison between the detected combustion ratio and the target combustion ratio, the ignition timing at which the detected combustion ratio becomes smaller is set. Advance, the ignition timing at which the detected combustion ratio is larger is delayed, or the actual crank angle at which this one or more predetermined combustion ratio is reached is detected, and based on the comparison between this detected crank angle and the target crank angle, Ignition timing control is performed by advancing the ignition timing when the target crank angle is advancing and delaying the ignition timing when the detection value crank angle is advancing. Based on this, ignition timing control is performed to reduce exhaust emissions and enable lean combustion to improve fuel efficiency.

According to a fifth aspect of the present invention, there is provided a method of controlling an engine, which is based on the detected combustion ratio or the detected crank angle when the load is smaller than a predetermined value or the engine speed is smaller than a predetermined value. While performing the ignition timing control and the fuel supply amount control, only the ignition timing control based on the combustion ratio is performed when the load or the engine speed is not in the above condition.

As described above, by effectively performing the ignition timing control based on the detected combustion ratio or the detected crank angle and the ignition timing control based on the combustion ratio, it is possible to achieve lean combustion while reducing exhaust emission and fuel consumption. Improve.

A sixth aspect of the engine control method of the present invention is characterized in that the ignition timing control and the fuel supply amount control are alternately performed.

As described above, the ignition timing control and the fuel supply amount control are alternately performed to reduce the exhaust emission while enabling lean combustion and improving fuel efficiency.

The engine control method according to a seventh aspect of the invention is characterized in that the first predetermined number of times of ignition timing control and the second predetermined number of times of fuel supply amount control are alternately performed.

As described above, the ignition timing control of the first predetermined number of times and the fuel supply amount control of the second predetermined number of times are alternately executed to reduce the exhaust emission and enable the lean combustion to improve the fuel consumption. Let

The engine control method according to the present invention is characterized in that the first predetermined number of times is equal to or larger than the second predetermined number of times.

As described above, the first predetermined number of times is equal to or larger than the second predetermined number of times, the fuel supply amount is effectively controlled, exhaust emission is reduced, lean combustion is enabled, and fuel consumption is improved. .

In the engine control method of the ninth aspect of the present invention, the lean fuel-air mixture is formed in the combustion chamber at the initial value of the fuel supply amount according to at least the load, and when the fuel is supplied to the engine. In addition to the above setting, it is characterized by having the data of the initial value of the fuel supply amount set so that the air-fuel ratio of the lean air-fuel mixture can be increased as the engine load decreases.

As described above, the data of the initial value of the fuel supply amount is held, accurate and easy control is ensured, the lean emission is possible while the exhaust emission is reduced, and the fuel consumption is improved.

According to a tenth aspect of the engine control method of the present invention, the ignition timing control based on the detected combustion ratio or the detected crank angle and the fuel supply amount control are carried out, the load is smaller than a predetermined value, or the engine is controlled. The target combustion ratio to be used under the first operating condition of at least one of the rotational speeds lower than the predetermined value is set to the second operating condition of performing only the ignition timing control based on the detected combustion ratio or the detected crank angle. The feature is that it is smaller than the target combustion ratio that is used at times.

In this way, the target combustion ratio used under the first operating condition is made smaller than the target combustion ratio used under the second operating condition in which only the ignition timing control is carried out, and the fuel supply amount control is made appropriate. To reduce exhaust emissions and enable lean combustion to improve fuel efficiency.

In the engine control method according to the invention of claim 11, the detected combustion ratio or the detected crank angle is
At least four crank angles consisting of a crank angle from the end of the exhaust stroke to the beginning of the compression stroke, a crank angle from the start of the compression stroke to ignition, and two crank angles within the period from the start of ignition to the start of the exhaust stroke. It is characterized in that the combustion pressure is detected and calculated based on these combustion pressure data.

In this way, the combustion pressure can be detected and appropriately calculated based on the combustion pressure data.

[0030]

BEST MODE FOR CARRYING OUT THE INVENTION An engine control method of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a block diagram of a multi-cylinder spark ignition type 4-cycle engine to which the present invention is applied. The engine 1 includes a crankcase 2, a cylinder body 3 and a cylinder head 4 above the crankcase 2. A piston 7 is slidably mounted in the cylinder body 3 via a connecting rod 8, and the connecting rod 8 is connected to a crankshaft 9. A ring gear 10 having a predetermined number of teeth is mounted on the crankshaft 9, and a crank angle sensor 11 that also functions as an engine speed sensor for detecting a rotational position of the ring gear 10 and measuring a crank angle and an engine speed is provided. Has been. A combustion chamber 13 is formed between the cylinder head 4 and the piston 7, and an ignition plug 400 is provided so as to face the combustion chamber 13.

A combustion chamber pressure sensor 5 for detecting the combustion pressure in the combustion chamber 13 is provided on the cylinder head 4 side. A cooling water jacket 6 is formed at appropriate positions on the cylinder head 4 and the cylinder body 3. Combustion chamber 13
An exhaust passage 15 and an intake passage 16 communicate with each other, and an exhaust valve 17 and an intake valve 18 are provided at the openings thereof.
A catalyst 23 such as an exhaust gas purifying three-way catalyst is provided in the middle of an exhaust pipe 22 connected to the exhaust passage 15, and a muffler 24 is provided at an end thereof. The exhaust pipe 22 is provided with an oxygen concentration sensor (O ₂ sensor) 25 and an exhaust pipe temperature sensor 120, each of which is connected to the control device 12.

A temperature sensor 26 is attached to the cylinder head 4, and temperature information of the combustion chamber 13 is sent to the control device 12. Further, the catalyst 23 is provided with a catalyst temperature sensor 150 connected to the control device 12. The kill switch 43 of the engine 1 is further connected to the controller 12 to obtain stop information for engine drive control.

On the other hand, an intake pipe 20 is connected to the intake passage 16, and the intake pipe 20 is connected to each cylinder via an intake distribution pipe 28. An intake pipe pressure sensor 32 is attached to the intake distribution pipe 28, and intake pipe pressure information is sent to the control device 12.
The EGR pipe 15 is formed by connecting the intake distribution pipe 28 and the exhaust pipe 22.
Two are provided. The EGR pipe 152 is provided with an EGR adjustment valve 151 connected to the control device 12. An air cleaner 35 is connected to the intake distribution pipe 28 via an intake pipe 33. The air cleaner 35 is provided with an intake air temperature sensor 36, and the intake air temperature information is sent to the control device 12. An intake air amount adjuster 30 is provided in the middle of the intake pipe 33, and a throttle valve 29 is attached to the intake air amount adjuster 30.

The throttle valve 29 is provided with a throttle opening sensor 31, which is connected to the control device 12. A throttle valve bypass passage 37 is provided in the intake pipe 33 of the intake amount adjuster 30, and a bypass passage opening adjustment valve 38 is provided in the bypass passage 37. The bypass passage opening adjustment valve 38 is connected to the control device 12. In the intake pipe 33, a hot-wire intake air amount sensor 34
Is provided, and the intake air amount information is sent to the control device 12.

On the upstream side of the intake valve 18 in the intake passage 16,
An injector 105 is provided for each intake port of each cylinder. The injector 105 is connected to the control device 12, and sends a control signal of the optimum injection amount calculated according to the operating state. Fuel is sent to each injector 105 through a fuel pipe 101a connected to each cylinder. The fuel pipe 101 a is branched from the fuel distribution pipe 104, and the fuel is supplied from the fuel tank 100 to the fuel distribution pipe 104 through the fuel supply pipe 101 and further through the filter 102 by the fuel pump 103. The fuel not injected from the injector 105 is collected in the fuel tank 100 through the fuel return pipe 107. A regulator 106 is provided on the fuel return pipe 107.
Is provided to keep the fuel injection pressure constant.

FIG. 2 is a flow chart of a main routine for controlling various operating states of the engine. Each step will be described below.

Step S11: Initialization is performed, and initial values are set in each flag value and each variable value.

Step S12: Intake air temperature sensor 36
Intake air temperature information from the heat ray intake air amount sensor 34
Intake air amount information from the throttle opening sensor 31, throttle opening information from the throttle opening sensor 31, intake pipe pressure information from the intake pipe pressure sensor 32, catalyst temperature information from the catalyst temperature sensor 150, crank angle information from the crank angle sensor 11. , Temperature information from the temperature sensor 26, exhaust pipe temperature information from the exhaust pipe temperature sensor 120, oxygen concentration information from the oxygen concentration sensor 25, and oil remaining amount information from an oil sensor (not shown), and the data is stored in the memory A. Store in (i).
The engine load can be grasped as an accelerator position or a throttle opening. If the throttle opening and the engine speed are determined, the intake air amount is determined during steady operation, so the intake air amount can be directly detected and regarded as the engine load. Further, since the intake pipe negative pressure has a constant relationship with the throttle opening if the engine speed is determined, the intake pipe negative pressure can be detected and regarded as the engine load.

Step S13: O of the kill switch 43
Switch information such as N, OFF, ON / OFF of a main switch (not shown) and ON / OFF of a starter switch (not shown) is fetched and stored in the memory B (i). The kill switch 43 is an emergency stop switch and is not provided in the vehicle engine, but is provided in, for example, a small boat engine.

Step S14: The operating state is judged based on the sensor information fetched in the step 12 and the switch information fetched in the step 13, and the memory is stored in correspondence with the operating state ,. Input the value corresponding to the variable C inside.

Operating state: a constant accelerator in which the throttle opening is not less than a predetermined value, the engine speed is not less than a predetermined value, and the rate of change of the throttle opening is not more than a predetermined value. State or MBA (Minimum Advance)
e Ignition for Best Torqu
e) Judge as the control state and store 1 in variable C.

Operating state: When the rate of change of the throttle opening is equal to or greater than a predetermined value, it is determined to be a transient operating state, and 2 is stored in the variable C.

Operating state: The throttle opening is below a predetermined value and the engine speed is within a predetermined range, for example, 1000 rp
In the case of m to 5000 rpm, it is determined to be the lean combustion control state, and 3 is stored in the variable C.

Operating state: When the engine is in an abnormal state such as an over-revolution in which the engine speed is equal to or higher than a predetermined limit value or an engine temperature is overheat in which the engine temperature is equal to or higher than a predetermined value, it is determined to be an abnormal operation state, and 4 is stored in a variable C.

Operating state: When the engine temperature is lower than a predetermined value and the starter switch is ON, it is determined to be a cold start state, and 5 is stored in the variable C.

Operating state: When the main switch is OFF or the kill switch is OFF, it is determined that the engine is in a stop request state, and 6 is stored in the variable C.

Operating state: When the clutch is neutral, the engine speed is below a predetermined value, or the idle SW (throttle fully closed SW) is ON, the idle mode is determined and 7 is stored in the variable C.

Operating state ... EGR control (control for recirculating a part of exhaust gas to the intake system) is determined to be EGR control mode when the switch is ON, and 8 is stored in variable C.

Operating state: When the engine temperature is equal to or higher than a predetermined value and the starter switch is ON, it is determined that the engine is normally started, and 9 is stored in the variable C.

Operating state A: When abnormal increase in combustion chamber pressure before spark ignition or abnormal transition of combustion chamber pressure is detected from the combustion chamber pressure data, it is determined as abnormal combustion state such as pre-ignition state or knocking state. Then, 10 is stored in the variable C.

With the same variable C value, the flag P = 1 is maintained and the number of times the step S14 in the main routine is checked. If R is exceeded a predetermined number of times, P = 0 is set.

When C = 1, the value of R is Rc = 1. When C = 2, the value of R is Rc = 2. When the value of C is 3, the value of R is changed to Rc = 3. Rc _{= 1} <Rc _{= 2} <Rc _{= 3} .

When the C value in the previous main routine is different from the C value in this time, P = 0 is set.

Step S15: It is determined whether or not the mode operation is executed. If the variable C is 4, 6, or 9, the process proceeds to step S20. Otherwise, the process proceeds to step S20.
Move to step S16.

Step S16: Based on the value of the flag P ,
When P = 0, the target combustion ratio according to the engine speed and the load is obtained from the map data (corresponding to FIG. 5) in the memory, and the result is stored in the memory D. Also,
The basic ignition timing, the basic fuel injection start timing, and the basic fuel injection amount are also obtained from the map data similar to those shown in FIG. 5 in the memory (the values given as a function of the engine speed and the load are illustrated), and the respective memory E '(1), E'
(2) Put in E '(3). After that, P = 1 is set.
However, even if P = 0 and the variable C is 5, the target combustion ratio is obtained based on the target combustion ratio map for cold start, and the value is stored in the memory D. If P = 1
Without doing anything, the process proceeds to step S17.

The combustion ratio means the ratio of the fuel burned up to a certain crank angle to the fuel burned in one combustion cycle. Regarding the method of calculating the combustion ratio, one method is to obtain the combustion chamber pressure data at a plurality of predetermined points in one combustion cycle by a linear approximation formula, and the other is to calculate the heat generation amount from the sampled pressure value. Is calculated by a thermodynamic formula to obtain the combustion ratio up to a predetermined crank angle (for example, top dead center). Both methods gave calculation results very close to the true value. In this case, the combustion chamber pressure data is obtained by detecting the combustion chamber pressure at the crank angle in the first period from the end of the exhaust stroke to the beginning of the compression stroke. In this case, the crank angle from the end of the exhaust stroke to the beginning of the compression stroke is the crank angle within the range where the pressure in the combustion chamber is the lowest and approaches the atmospheric pressure. A point or its vicinity. That is, 4
In the cycle engine, as shown in FIG. 6, the combustion gas in the combustion chamber is discharged by the exhaust stroke from the bottom dead center after the explosion, and the pressure in the combustion chamber decreases and approaches the atmospheric pressure as it approaches the top dead center. In the intake stroke after the top dead center, the state close to the atmospheric pressure is maintained due to the introduction of fresh air, and the pressure is gradually increased from the compression stroke after the bottom dead center which is started after the exhaust valve 17 is closed after the intake stroke. The pressure inside the combustion chamber is detected at one point within the range where the pressure inside the combustion chamber decreases and approaches the atmospheric pressure. Although the crank angle a0 is set to BDC in FIG. 6, it may be set to BDC after the compression stroke at the beginning of the compression stroke. Of course BD
The crank angle during the intake stroke before C may be used. On the other hand, in the two-cycle engine, as shown in FIG. 21, when the piston lowers and the pressure drops after the explosion and the exhaust port opens, the pressure in the combustion chamber further decreases accordingly, and when the scavenging port opens, fresh air is released from the crank chamber. As it is introduced, it approaches atmospheric pressure. When the piston rises from the bottom dead center with the exhaust port open, the scavenging port closes and the exhaust port opens, the compression starts and the pressure gradually increases. That is, from the end of the exhaust stroke to the beginning of the compression stroke, after the exhaust port is opened and the exhaust port is open after the start of exhaust, the scavenging port is opened and intake is started, and then the exhaust port is closed. This is the period until the compression starts. In FIG. 21, the crank angle a0 is taken as BDC.

Spark ignition is performed before or after top dead center after compression. (Spark ignition is started at the crank angle represented by the arrow and S in FIGS. 6 and 21, respectively.) Spark ignition is started, and ignition is started with a slight delay, and combustion is started. The ignition start referred to in each claim is the moment when this ignition combustion is started. That is, the crank angle (FIG. 6, FIG. 2) in the second period, which is the period from the start of the compression stroke to the start of ignition and combustion.
In both cases, the pressure in the smelting chamber is detected at the crank angle a1). After this, the third period, which is the period from the start of ignition (start of ignition and combustion) to the start of the exhaust stroke during the explosive combustion stroke
Of two crank angles (for example, in FIG. 6 and FIG. 21, crank angle a2a3 or crank angle a
2, a4, or crank angles a3, a4, crank angles a2, a5, crank angles a3, a5, or crank angles a4, a5), the pressure in the combustion chamber is detected. It is desirable that one of the two crank angles within this period be before the crank angle at which the maximum combustion pressure is reached. Further, when the pressure in the combustion chamber is detected at four or more crank angles, for example, at five or more crank angles referred to in each claim, the number of pressure measurement crank angle points in the first or second period is increased. May be. Further, preferably, the pressure may be detected at three or more crank angles within the third period as in the embodiment of FIGS. In a diesel engine, fuel injection into the combustion chamber before or after top dead center after compression is started, and after a short delay, combustion starts due to spontaneous ignition. That is, in the diesel engine, the ignition start described in each claim means the moment when the spontaneous ignition is started. Note that the ignition delay from the start of fuel injection to the start of spontaneous ignition is obtained in advance as data based on the engine speed or the load, and this is factored in to calculate the pressure measurement crank angle within the second period and the pressure crank within the third period. The pressure of the combustion chamber is measured by storing the corner points in the memory as data based on the engine speed or the load.

One point in the first period and one in the second period
Point, the combustion chamber pressure at a crank angle of at least 4 points in total of 2 points in the third period is detected, and the combustion ratio is calculated from this by a linear approximation. This approximation formula is combustion rate qx = a + b1 * (P1-P0) + b2 * (P
2-P0) + ... + bn * (Pn-P0).

As can be seen from the above equation, qx is obtained by subtracting the reference pressure P0 from the pressure data P1 to Pn, respectively.
Multiplying the constants b1 to bn by a preset constant a
It is expressed by adding.

Similarly, Pmi is also represented by subtracting the reference pressure P0 from the pressure data P1 to Pn, multiplying the preset constants C1 to Cn, and adding the preset constant.

Here, P0 is the combustion chamber pressure at the point of the atmospheric pressure level (for example, the crank angle near BDC as described above), and each pressure value of P1 to Pn is used to correct the offset voltage due to the drift of the sensor. Drawn from. Further, P1 is the combustion pressure at the crank angle a1 in the first period, and P2 is the combustion chamber pressure at the crank angle a2 in the second period. P3 to Pn are crank angles a3 to an (n = 5 in this embodiment) in the third period.

By such a simple first-order approximation calculation, the combustion ratio up to a predetermined crank angle after ignition can be calculated to be exactly the same as the actual value in a short time. Therefore,
By controlling the ignition timing and the air-fuel ratio of the engine by using such a combustion ratio, it is possible to efficiently take out the energy due to combustion and improve the responsiveness, for example, when performing lean burn control or EGR control. The output fluctuation can be suppressed by accurately following the operating state. Further, it is possible to prevent the generation of NOx due to the rapid progress of combustion. In the second qx calculation method, the amount of heat generated between two pressure measurement points (crank angle) is ΔP for the differential pressure at both pressure measurement points, ΔV for the combustion chamber volume difference, and The front pressure value and the combustion chamber volume value are P, V, and A.
Is heat equivalent, K is specific heat ratio, R is average gas constant, P0 is BD
Assuming the pressure value at C, the heat generation amount Qx = A / (K-1) * ((K + 1) / 2 * ΔP * ΔV
+ K * (P−P0) * ΔV + V * ΔP) can be obtained.

The combustion rate up to the predetermined pressure measurement point is
The crank angle at which combustion is almost completed is selected as the pressure measurement point, and the crank angle near ignition is similarly selected as the pressure measurement point, and the heat generation amount Qx is measured at each pressure measurement point measured during that time. Is the sum of the calculated values of the above, and is the sum of the calculated values of Qx from the first pressure measurement point to the predetermined pressure measurement point (predetermined crank angle). .

That is, the combustion rate qx = heat quantity burned up to an arbitrary crank angle / total heat quantity × 100 (%) = (Q1
+ Q2 + ... + Qx) / (Q1 + Q2 + ... + Q
n) × 100.

With the above calculation method, the combustion chamber pressures at a plurality of predetermined crank angles are measured (at step S112 in FIG. 3), and the combustion ratio up to the predetermined crank angle is accurately calculated based on the data. It is possible (at step S201 of FIG. 7). By controlling the engine using this combustion ratio, stable output and engine rotation can be obtained.

Step S17: An injection amount correction calculation for fuel injection is performed based on the intake air temperature information and the intake pipe negative pressure information. That is, when the intake air temperature is high, the air density is low, and the air flow rate is substantially reduced. Therefore, the air-fuel ratio in the combustion chamber becomes low. Therefore, a correction amount for reducing the fuel injection amount is calculated.

Step S18: The basic fuel injection start, the basic fuel injection amount, and the basic ignition timing according to the engine load and the engine speed are obtained in step S16 and are included in E '(i). Based on this, the fuel injection correction amount and the ignition timing correction amount are calculated according to the correction amount calculated in step S17 and the information stored in the memory A (i), and the control amount is calculated in addition to the reference values. The control amount is set to the memory E (1) for the ignition start timing, the memory E (2) for the ignition period, and the injection start timing and the injection end timing are set to F when P = 1.
When (3), F (4) and P = 0, the injection start timing and the injection end timing are put into E (3) and E (4).

This is input to the memory E (i). Similarly, the control amounts of the servo motor group and the solenoid valve group are calculated according to the information stored in the memory A (i) and are stored in the memory G (i).

Step S19: The actuators such as the servo motor group and the solenoid valve group are driven and controlled according to the control amount of the memory G (i).

Step S20: The engine stop request is judged, and if the variable C is 6, the process proceeds to step S21, and if not, the process proceeds to step S22.

Step S21: Memory E (i) i = 1 to 1
Stop data is set to 4 to 0, or the spark plug 400 is misfired.

Step S22: It is judged whether or not the variable C is 9, and when the variable C is 9 and the normal engine is started, the process proceeds to step S23, and when not, the process proceeds to step S25.

Step S23: The memory F (i) is set with data stored in advance for starting, that is, data for retarding the ignition timing and slightly increasing the fuel injection amount.

Step S24: The starting motor is driven.

Step S25: When the variable C is 4, the data corresponding to the abnormality content is stored in the memory F (i), for example, the data for increasing the fuel injection amount while narrowing the throttle opening in the case of over-revolution and misfire for over-heating. Set.

Next, the interrupt routine of FIG. 3 will be described. This interrupt routine is executed by interrupting the main routine when a crank signal of a predetermined angle is input.

Step S111: The timer is set so that the interrupt routine is executed at every predetermined crank angle, that is, the interrupt is generated at the next crank angle.

Step S112: The pressure data of the crank angle at which the interruption occurs is fetched and stored in the memory.

Step S113: When the pressure data of all crank angles are taken into the memory, the process proceeds to step S114.

Steps S114 to S115: Variable C is 1
It is checked whether or not 0, and if C = 10, it is determined that abnormal combustion has occurred, and the abnormal combustion prevention routine of step S115 is performed and the routine returns. If not, the process proceeds to step S116.

Step S116: Whether C = 2 is checked to determine whether it is in a transient state. If so, a transient control routine is executed in step S116a to correct the ignition timing and A / F and return. To do. If not, the process proceeds to step S117.

Step S117: Whether C = 5 is checked to determine whether or not it is a cold start, and if so, a cold start control routine is executed in step S117a to correct the ignition timing and then return. If not, the process proceeds to step S118.

Step S118: Whether C = 8 is checked to determine whether the mode is the EGR control mode, and if so, the EGR control routine is executed in step S118a to correct the EGR rate and ignition timing, and then the process returns. . If not, the process proceeds to step S119.

Step S119: Whether C = 3 is checked to determine whether the lean combustion mode is set. If so, the lean burn control routine is executed at step S119a to correct the A / F and ignition timing. And return. If not, the process proceeds to step S120.

Step S120: Whether C = 7 is checked to determine whether it is in the idling mode, and if so, an idling control routine is executed in step S120a to correct the A / F and ignition timing and then return. . If not, the MBT control routine is executed in step S121 to correct the ignition timing and the process returns.

Next, the interrupt routine of FIG. 4 will be described. This interrupt routine is executed by interrupting the main routine when the reference crank signal is input.

Step S121: Since this interrupt routine is executed once at the engine rotation and the predetermined crank angle, the cycle is measured.

Step S122: The engine speed is calculated.

Step S123: Memory F (i), i =
Based on the control data of 1 to 4, the ignition start timing, the ignition end timing, the injection start timing, and the injection end timing are set in the timer. The timer activates the ignition device and the injection device at the set timing.

Next, the calculation of the target combustion ratio described with reference to FIGS. 2 and 3 will be described in detail.

FIG. 5 is a map diagram for obtaining the target combustion ratio according to the engine speed and the load. The target combustion ratio at a predetermined crank angle, for example, ATDC of 50 degrees, is obtained from a map of the target combustion ratio at the time of lean combustion, and is stored in the storage device of the control device 12. It shows a three-dimensional configuration in which the target combustion ratio is determined by the load (Lx) and the engine speed (Rx). The target combustion ratio under predetermined operating conditions (Lx, Rx) is FMB ₀
(Lxi, Rxi), i = 1 to n.

Target combustion rate data at a plurality of crank angles is provided as the target combustion rate data in accordance with the operating state. For example, target combustion ratio data of a predetermined crank angle in the early stage of combustion and a plurality of predetermined crank angles in the latter stage of combustion are provided.

FIG. 6 is a graph of combustion chamber pressure for one cycle of combustion in a four-cycle engine. The horizontal axis is the crank angle,
The vertical axis represents the combustion pressure. The crank angle is a0
The combustion pressures P0 to P5 at the six points a5 are detected, and the combustion ratio is calculated based on these pressure values. a0 is the bottom dead center position (BDC) where the suction shifts to the compression shift, which is a state close to the atmospheric pressure. a1 is after compression start but before spark ignition,
a2 is a crank angle after reaching the top dead center (TDC) after spark ignition at S. The four points a3 to a5 are crank angles in the explosion stroke after top dead center. The combustion ratio is calculated based on the pressure data at these points. In the case of a diesel engine that does not perform spark ignition, F
Like I, the fuel is injected near the top dead center. Spontaneous ignition occurs after a delay corresponding to the crank angle d after the start of injection. The crank angle for spontaneous ignition is S. Instead of controlling the ignition timing in the ignition spark engine, in the present diesel engine, the control of the fuel injection timing is performed based on the measured combustion ratio or the measured crank angle based on the difference between the target combustion ratio and the target crank angle, respectively. The injection start timing is advanced / retarded, and the injection end timing is controlled so as to secure a predetermined injection amount.

Next, the lean burn control described with reference to FIG. 3 will be described in detail. FIG. 7 is a flow chart of a lean burn control routine when the target value is set as the burn rate at a predetermined crank angle.

Step S201: Burning ratio FMB (θ)
Is calculated and the process proceeds to step S202.

Step S202: Counter FCOUNT
Is 0 (the ignition timing control has been executed a set number of times), the process proceeds to step S203 to operate the fuel supply amount. If not, the process proceeds to step S207 to perform the correction control of the ignition timing.

Step S203: Burning ratio FMB (θ)
If is greater than or equal to the determination reference value FMBX, the process proceeds to step S204. If not, the process proceeds to step S205.

Step S204: Fuel supply correction coefficient FT
D is operated toward the predetermined value reduction side by the fuel supply amount correction step FTDD on the reduction side, and the process proceeds to step S206.

Step S205: Fuel supply correction coefficient FT
D is operated to the predetermined value decrease side by the fuel supply amount correction step FTDI on the increase side, and the routine proceeds to step S206.

Step S206: Counter FCOUNT
Then, the number of times FCMAX of executing the ignition timing control is set (so that the ignition timing control will be executed from the next time) and the routine returns.

Step S207: The ignition timing correction control routine is executed to optimize the ignition timing.
Move to 208.

Step S208: Counter FCOUNT
It subtracts 1 from it and returns.

FIG. 8 shows that the optimum ignition timing and combustion speed are obtained by the feedback correction control of the ignition timing and the fuel supply amount, whereby the output can be diluted without causing fluctuations in output and deterioration of HC emissions. 9 shows a flowchart of a control routine that can improve fuel efficiency and suppress NOx emissions.

There are target combustion ratios at a plurality of crank angles, of which the early combustion ratio is the target value for controlling the ignition timing, and at least the change ratio of the combustion ratio between two crank angles is the combustion speed control. And the target value for.

The ignition timing control is the ignition timing, and the combustion speed control is the manipulated variable of the fuel supply amount. This operation amount is determined by feeding back the difference between the target value and the detected value.

Step S500: The target combustion ratios at a plurality of crank angles corresponding to the current engine speed and load are read from the map stored as target data at the time of lean combustion. The above is performed, and it moves to step S501.

Step S5O1: The target combustion rate is calculated from the plurality of target ratios read in step S500. For example, the target combustion speed BSPD is obtained by dividing the change in the combustion ratio at two crank angles by the crank angle interval.

BSPDθ12 = (FMBθ2-FMBθ
l) / (θl) FMBθ2> FMBθ1, θ2> θ1 If the target value read from the map in step S500 is set by combustion speed, step S501 need not be executed. The above is performed and it moves to step S502.

Step S502: The actual combustion rate at a plurality of crank angles for which the target combustion rate is set is calculated (hereinafter sometimes referred to as a detected value or a detected combustion rate). From this, the combustion speed is also calculated by the same formula as in step S501. Then, the process proceeds to step S503.

Step S503: The deviation between the target value and the detected value is calculated. For example, the deviation ΔFBM of the combustion ratio is calculated by the difference between the detected combustion ratio FMB (θ1) and the target combustion ratio FMBθ1.

ΔFMB = FMB (θ1) -FMB θ1 Similarly, the combustion speed deviation ΔBSPD is the detected combustion speed.
De BSPD (θ12), target combustion speed and BSPDθ
The difference is 12.

BSPD = BSPD (θ12) −BSPDθ12 The above calculation is performed, and the process proceeds to step S504.

Step S504: Check the feedback inhibition flag of the fuel supply amount correction control. When the feedback inhibition flag is ON, the process proceeds to step S509 and the correction control of the fuel supply amount is not performed. If the feedback flag is OFF, the process moves to step S505 and continues the process. The feedback inhibition flag of the combustion supply amount correction control may be turned on even during the lean burn operation mode. For example, there is a case where the fuel cell is forcibly made rich in order to recognize the variation between the cylinders, and a case where it is made rich for the purpose of improving the exhaust gas purification rate. In such a case, it is turned on for a predetermined cycle or a predetermined time. The above is performed and it moves to step S505.

Step S505: It is determined whether the correction control of the fuel supply amount is in the delay cycle. The delay cycle is a cycle for executing the correction with an interval. As a result, response delay and surge fluctuations are absorbed. The correction control is executed when the delay counter becomes 0, and the process proceeds to step S506. If not, the process moves to step S506b.

Step S5O6: Here, it is confirmed whether the deviation between the target value and the detected value is within the allowable value. This allowance is provided to prevent engine hunting. If it is within the allowable value, the correction control is not performed, and the process proceeds to step S508. If not, the process proceeds to step S507, and correction control of the fuel supply amount is executed.

Step S507: The routine for correcting the fuel supply amount shown in FIG. 10 is executed, and the routine proceeds to step S508.

Step S5O8: The delay counter is set to a predetermined value so that the next predetermined number of delay cycles will occur, and the routine goes to Step S509.

Step S5O6b: The delay counter of the fuel supply amount correction control is decremented by 1, and the process proceeds to step S507b.

Step S507b: Deviation is averaged. Further, it is also possible to evaluate the validity of the correction by calculating the fluctuation rate of the detected value and obtaining the stability of combustion. After performing the above, the process proceeds to step S509 without correction.

Step S509: It is determined whether it is a delay cycle of ignition timing correction control. The delay cycle is a cycle for performing correction with an interval, and absorbs surge-like fluctuations. The correction control is executed when the delay counter becomes 0, and the process proceeds to step S510. If not, the process proceeds to step S510b.

Step S510: Here, it is confirmed whether the deviation between the target value and the detected value is within the allowable value. This allowable value prevents engine hunting. If it is within the allowable value, the correction control is not performed and the process proceeds to step S512. If not, the process proceeds to step S511, and ignition timing correction control is executed.

Step S511: The ignition timing correction routine of FIG. 9 is executed, and the routine proceeds to step S512.

Step S512: Set a predetermined value in the delay counter so that the next time the predetermined number of delay cycles will occur, and then return.

Step S510b: The delay counter of the ignition timing correction control is decremented by 1, and the process proceeds to step S51OΦ.

Step S51lb: Deviation is averaged. It is also possible to evaluate the validity of the correction by calculating the fluctuation rate of the detected value and obtaining the stability of the period. The above is performed and the process returns without correction.

Next, FIG. 9 is a flowchart of the ignition timing correction control when the target value is set as the combustion ratio at the predetermined crank angle. The operation of this ignition timing correction routine is shown in FIG.

Step S151: The deviation ΔFMB between the target combustion ratio FMB and the actual value FMB (θ) is taken, and the routine goes to Step S152.

Step S152: The correction change amount gi is read from the map according to the deviation ΔFMB, and the step S152 is performed.
Move to 153.

Step S153: The ignition timing correction value IGTD is added to the ignition timing correction value IGTD up to the previous time to obtain the ignition timing correction value IGTD, and the routine proceeds to step S154.

Step S154: Ignition timing correction value IGT
If D is positive, the process moves to step S155a. If negative or 0, the process proceeds to step S155b.

Steps S155a to S156
a: The ignition timing correction value IGTD is the limit IGT on the advance side
If it is not in the DS, step S156a is executed, a restriction is applied, and the process returns. If it is in the limit IGTDS, return as it is.

Steps S155b to S156
b: Limit IGT when the ignition timing correction value IGTD is on the retard side
If it is not in the DR, step S156b is executed, a restriction is applied, and the process returns. If it is in the limit IGTDR, return as it is.

Next, FIG. 10 shows a fuel supply amount correction routine when the correction value is calculated according to the deviation. The operation of this fuel supply amount correction routine is shown in FIG.

Step S171: The deviation ΔFMB between the target combustion ratio FMB and the actual value FMB (θ) is taken, and the routine proceeds to step S172.

Step S172: The correction change amount gf is read from the map according to the deviation ΔFMB, and step S17
Move to 3.

Step S173: The correction value FTD of the fuel supply amount up to the previous time is added with the correction change amount gf to obtain the correction value FTD of the fuel supply amount, and the routine goes to Step S174.

Step S174: Correction value F of fuel supply amount
If TD is positive, the process moves to step S175a. If negative or 0, the process proceeds to step S175b.

Steps S175a to S176
a: The correction value FTD of the fuel supply amount is the limit FT on the increasing side
If it is not in the DMX, step S176a is executed, a restriction is applied, and the process returns. If it is in the limit FTDMX, return as it is.

Steps S175b to S176
b: The correction value FTD of the fuel supply amount is the limit FT on the reduction side
If it is not in the DMN, step S176b is executed, a restriction is applied, and the process returns. If it is in the limit FTDMN, it returns as it is.

In such lean burn control, combustion variations and HC emissions are reduced, and lean lean is made infinitely. It has a target value map for lean burn control as a control target value.

In order to determine the allowable limit of increase in HC emissions and output instability, the combustion ratio in the latter stage of combustion or the crank angle is set as the target value. For example, (a) crank angle TD
It is possible to set a combustion rate at C50 ° and a crank angle of (b) combustion rate of 70% as target values.

This target value indicates the allowable limit of deterioration of combustion. In the case of (a), when the combustion ratio is smaller than the target value, and in the case of (b), the deterioration state is shown when it is larger than the target value.

The lean burn control routine is a subroutine of a burn rate control routine that is executed for each engine revolution, and is executed when the control mode determined by the main routine according to the operating state is the lean burn control.

When this lean burn control routine is executed, a target value obtained in advance is loaded or the actual combustion ratio is calculated, and correction control of ignition timing and fuel supply amount is alternately performed and the correction value is stored. .

If the combustion ratio is within the criterion, it is determined that further leaning is possible, and the fuel is reduced by a predetermined amount. If not, it is determined that the fuel cannot be diluted any further and the fuel is increased by a predetermined amount. In a few cycles after the fuel supply amount is manipulated as described above, the ignition timing correction control is executed to optimize the ignition timing so that the combustion ratio becomes the target value.

FIG. 13 is a graph showing the tendency of the change of the combustion ratio when the fuel supply amount is changed. 8A is appropriate A /
When richer than F, 8B indicates a proper A / F, 8C indicates a leaner than proper A / F, and the actually measured combustion ratio at a predetermined crank angle (for example, B) is greater than the target combustion ratio (for example, A). If it is large a1, the amount of fuel is reduced.
If a2 is smaller than the target combustion ratio (for example, A), the amount of fuel is increased.

Further, if the actually measured crank angle reaching the predetermined combustion ratio (eg A) is b2 larger than the target crank angle (eg B), the amount of fuel is increased. If b1 is smaller than the target crank angle (for example, B), the fuel amount is reduced.

That is, the initial value of the fuel supply amount at least according to the load, and the initial value of the fuel supply amount set so that the lean air-fuel mixture is formed in the combustion chamber when the fuel is supplied to the engine. And holds the combustion ratio at a predetermined crank angle in the memory as map data of the target combustion ratio corresponding to at least one of the load and the engine speed, or the crank angle that reaches the predetermined combustion ratio is Either the map data of the target crank angle corresponding to at least one of the engine speed is retained in the memory, or the actual combustion ratio up to this predetermined crank angle is detected, and the detected combustion ratio and the target combustion ratio are compared. Based on the above, the fuel supply amount should be increased when the detected combustion ratio is smaller and the fuel supply amount should be decreased when the detected combustion ratio is larger. Or, the actual crank angle that reaches this predetermined combustion ratio is detected, and based on the comparison between this detected crank angle and the target crank angle, the fuel supply amount is increased when the target crank angle is ahead, and the detected value Lean combustion is enabled by performing either fuel supply amount control to reduce the fuel supply amount when the crank angle is advancing,
Improves fuel efficiency while reducing exhaust emissions.

FIG. 14 shows the combustion ratio FM depending on the ignition timing operation.
It is a figure which shows the change of B. 10A indicates a case where the ignition timing is advanced from the proper ignition timing, 10B indicates a case where the ignition timing is retarded from the proper ignition timing, and 10C indicates a case where the ignition timing is retarded from the appropriate ignition timing. If a1 is larger than the ratio (for example, A), the angle is retarded. Also,
If a2 is smaller than the target combustion ratio (for example, A), the advance is made.

If the actually measured crank angle reaching the predetermined combustion ratio (eg A) is larger than the target crank angle (eg B) by b2, the engine advances. If b1 is smaller than the target crank angle (for example, B), it is retarded.

That is, the initial value of the ignition timing corresponding to at least one of the load and the engine speed is used as data, and the combustion ratio at a predetermined crank angle is set to the target combustion ratio corresponding to at least one of the load and the engine speed. Of the target crank angle corresponding to at least one of the load and the engine speed, which is stored in the memory as map data of the target crank angle. The actual combustion ratio up to the corner is detected, and based on the comparison between the detected combustion ratio and the target combustion ratio, the ignition timing at which the detected combustion ratio becomes smaller is advanced, and the ignition timing at which the detected combustion ratio becomes larger is set. The actual crank angle that delays or reaches the predetermined combustion rate is detected, and the detected crank angle and the target crank angle are detected. Based on the comparison with the crank angle, advance the ignition timing when the target crank angle is ahead and delay the ignition timing when the detected value crank angle is advanced. Thus, lean combustion is enabled, and the fuel efficiency is improved while reducing the exhaust emission. FIG. 15 is a graph showing a change in data when the lean combustion control is executed. 15A shows a change in the A / F value, FIG. 15B shows a change in the target combustion ratio FMB due to the ignition timing operation, FIG. 15C shows an ignition timing correction value IGT, and FIG. (D) shows the fuel supply amount correction value. When the lean burn control is started, the ignition timing correction value IGT is used to adjust the advance / retard angle and the fuel supply amount so that the A / F value remains constant at an appropriate value. The amount increase / decrease is corrected according to the value, and the fuel supply amount correction control has data of the initial value of the fuel supply amount, and the appropriate correction is performed based on this.

That is, as the lean burn control, the target burn rate has a permissible range, and the first target burn rate larger than the target burn rate in the map data and the second target burn rate smaller than the target burn rate in the map data. When the detected combustion ratio is lower than the second target combustion ratio, the fuel supply amount is increased, and when the detected combustion ratio is higher than the first target combustion ratio, the fuel supply amount is decreased. Is between the first target combustion ratio and the second target combustion ratio, either the fuel supply amount is not changed, or the target crank angle is allowed to have an allowable width, and the first crank angle advanced from the target crank angle in the map data is set. By setting the target crank angle and the second target crank angle that is later than the target crank angle in the map data, the fuel supply amount is reduced when the detected crank angle is ahead of the first target crank angle, and the detected value When the crank angle is behind the second target crank angle, the fuel supply amount is increased, and when the detected crank angle is between the first target crank angle and the second target crank angle, the fuel supply amount is not changed. It is advisable to carry out any one of the fuel supply amount control. Alternatively, the control is based on the magnitude relationship between the first target combustion ratio, the second target combustion ratio, and the detected combustion ratio when the load is smaller than a predetermined value or the engine speed is smaller than a predetermined value. One or both of the fuel supply amount control and the ignition timing control based on the advance / retard relationship between the first target crank angle, the second target crank angle, and the detected crank angle.

FIG. 16 is a graph showing the correlation between the combustion ratio and the HC and NOx emission amounts when the A / F value is lean and the predetermined crank angle ATDC is 50 °. FIG. 17 is a graph showing the correlation between the combustion ratio and the output variation when the A / F value is lean and the predetermined crank angle ATDC is 50 °. For example, the combustion ratio FM when the predetermined crank angle ATDC is 50 °
Bij is 70%, the amount of HC and NOx emissions is small,
Output variation is also small.

The target crank angle can be obtained from the map data shown in FIG. That is, in FIG. 18, the horizontal axis represents the load (L) and the vertical axis represents the target crank angle CRA that should reach the predetermined combustion ratio.
Target crank angle CR that should reach 0%, 70%, 80%, etc.
A ₀ (Rx, Lx) is the actual engine speed rpm (R
x) and the actual engine load (Lx) are obtained from the map. Target crank angle CRA ₀ (Rxi,
Lxi) is calculated as i = 1 to n. Crank angle value data that reaches a plurality of combustion ratios is provided as crank angle value data that reaches a predetermined combustion ratio when a normal combustion state is obtained.

FIG. 19 shows that the combustion ratio is 7 when the A / F value is lean.
It is a graph which shows the correlation of a crank angle at 0%, and HC and NOx emission. FIG. 20 is a graph showing the crank angle and output variation when the A / F value is lean and the combustion ratio is 70%. For example, the predetermined combustion rate FMBij is 70%
When the crank angle θij is 50 degrees ATDC, H
C, NOx emissions are small, and output variations are small.

FIG. 21 is a graph of combustion chamber pressure similar to that of the above-described four-cycle engine and FIG. 6 for showing combustion pressure data detection points for measuring the combustion ratio of the two-cycle engine. As mentioned above, combustion chamber pressure data is sampled at 6 crank angles. In the drawing, the range of A is the crank angle region where the exhaust port is open, and the range of B is the crank angle region where the scavenging port is open. The method of calculating and calculating each crank angle (a0 to a5) is substantially the same as that of the above-described 4-cycle engine, and in step S113 of the interrupt routine of FIG.
The combustion pressures P0 to P5 at the six points a0 to a5 where the crank angle is shown are detected, and the combustion ratio is calculated based on these pressure values. Each of the embodiments of the present invention can also be adopted in which combustion is supplied by a vaporizer.

In the above lean burn control, when the load is smaller than the predetermined value or the engine speed is smaller than the predetermined value, at least one of the detected combustion ratio and the detected crank angle is used to control the ignition timing. While the fuel supply amount control is performed, only the ignition timing control based on the combustion ratio may be performed when the load or the engine speed is not in the above condition.

Alternatively, the ignition timing control and the fuel supply amount control may be alternately performed. In this case, for the ignition timing control, the first combustion ratio larger than the target combustion ratio in the map data
If the detected combustion ratio is larger than the target combustion ratio, the ignition timing is retarded, and if the detected combustion ratio is smaller than the second target combustion ratio smaller than the target combustion ratio in the map data, the ignition timing is advanced and the detected value is the first value. When it is an intermediate value of the second target combustion ratio, control is performed to maintain the ignition timing as it is. Regarding the fuel supply amount control, the fuel is reduced when the detected combustion ratio becomes equal to or lower than the second target combustion ratio, and other than that. If it is larger than the second target combustion ratio, the control for increasing the fuel may be always performed.

In the alternate execution, the ignition timing control of the first predetermined number of times and the fuel supply amount control of the second predetermined number of times may be alternately performed.

In this control, the second predetermined number of times is made larger than the first predetermined number of times.

In the lean burn control of the above embodiment, it is an initial value of the fuel supply amount according to at least the load, and is set so that the lean air-fuel mixture is formed in the combustion chamber when the fuel is supplied to the engine. At the same time, as the engine load decreases, it is possible to have data with the initial value of the fuel supply amount set so that the air fuel consumption of the lean air-fuel mixture can be increased. Further, the ignition timing control based on the detected combustion ratio or the detected crank angle and the fuel supply amount control are executed. At least one of a load smaller than a predetermined value and an engine speed smaller than a predetermined value The target combustion ratio to be used under the operating condition of 1 may be made smaller than the target combustion ratio to be used under the second operating condition in which only the ignition timing control based on the detected combustion ratio or the detected crank angle is executed.

Further, the detected combustion ratio or the detected crank angle is the crank angle from the end of the exhaust stroke to the beginning of the compression stroke, the crank angle from the start of the compression stroke to ignition, and the period from the start of ignition to the start of the exhaust stroke. It is also possible to detect the combustion pressure at at least four crank angles of the two crank angles and calculate it based on these combustion pressure data.

[0164]

As described above, the invention according to claim 1 detects the actual combustion ratio up to one or more predetermined crank angles, and detects the actual combustion ratio based on the comparison between the detected combustion ratio and the target combustion ratio. When the combustion ratio is lower, the fuel supply amount is increased, and when the combustion ratio is higher, the fuel supply amount is decreased, or the actual crank angle at which one or more of the predetermined combustion ratios is reached is detected. Then, based on the comparison between the detected crank angle and the target crank angle, the fuel supply amount is increased when the target crank angle is advanced, and the fuel supply amount is decreased when the detected value crank angle is advanced. Since any one of the fuel supply amount control is performed, the fuel supply amount control is performed based on the combustion ratio up to a predetermined crank angle to reduce exhaust emission and enable lean combustion to improve fuel efficiency.

According to the second aspect of the present invention, the target combustion rate is allowed to have an allowable range, and the target combustion rate is given in the map data, and the target crank angle is allowed to have an allowable range. As described above, the fuel supply amount control is performed simply and accurately based on the combustion ratio up to the predetermined crank angle, and lean combustion is enabled and fuel efficiency can be improved while reducing exhaust emission. In order to keep the combustion ratio within the target value (strictly speaking, close to the target value), if the control is not stopped with a certain allowance, the combustion ratio will be affected by data reading errors, disturbances (noise) and combustion variations. Hunting becomes large and the output is adversely affected. Therefore, the allowable width is necessary.

Since the purpose of lean combustion is to lean the fuel as long as the target value of the burning ratio is satisfied, the fuel amount is reduced when it is in the allowable range or larger. However, when the value is smaller than the allowable value, the amount of fuel needs to be increased because it is too lean.

As described above, it is possible to realize stable leaning within the allowable range without making the boundary (decision value) of the fuel increase / decrease amount the same as the target value of the combustion ratio.

According to the third aspect of the present invention, the engine output can be stabilized by controlling the fuel supply amount based on the load or the engine speed.

According to the fourth aspect of the present invention, the actual combustion ratio up to one or more predetermined crank angles is detected, and the detected combustion ratio is smaller based on the comparison between the detected combustion ratio and the target combustion ratio. The ignition timing is advanced to delay the ignition timing at which the detected combustion ratio is larger, or the actual crank angle at which one or more of the predetermined combustion ratios is reached is detected, and the detected crank angle and the target crank angle are Based on the comparison, the ignition timing control is performed by advancing the ignition timing at which the target crank angle is advanced and delaying the ignition timing at which the detected value crank angle is advanced. It is possible to perform lean combustion and improve fuel efficiency while controlling the ignition timing based on the combustion ratio up to and reducing exhaust emission.

According to the fifth aspect of the present invention, the fuel supply amount control based on the detected combustion ratio or the detected crank angle and the ignition timing control based on the combustion ratio are performed in combination to reduce exhaust emission and enable lean combustion. And fuel efficiency can be improved. Further, since the lean-burn is performed at the optimum ignition timing, the lean-burn can be further leaned and the stability of the fuel is not deteriorated as compared with the case where only the fuel supply control is performed.

According to the sixth aspect of the present invention, the ignition timing control and the fuel supply amount control are alternately performed, and by combining different controls, it is possible to achieve lean combustion and improve fuel efficiency while reducing exhaust emission. it can. Further, the fuel supply amount and the ignition timing suitability can be confirmed by performing them alternately.

According to the seventh aspect of the present invention, the first predetermined number of times of ignition timing control and the second predetermined number of times of fuel supply amount control are alternately performed, and more precise control is performed to achieve exhaust emission. While reducing the fuel consumption, lean combustion is possible and fuel efficiency can be improved.

According to an eighth aspect of the present invention, the fuel supply amount control is performed by increasing the first predetermined number of times rather than the second predetermined number of times.
It is possible to bring the amount of fuel supply close to an appropriate amount, and it is possible to achieve lean combustion and improve fuel efficiency while reducing exhaust emissions.

Further, according to the invention described in claims 7 and 8, it becomes possible to absorb the time constant until it is reflected in the combustion when the fuel supply amount is changed, so that the overcorrection can be prevented and the combustion can be prevented. It also has the effect of ensuring stability.

The invention according to claim 9 has data of the initial value of the fuel supply amount, ensures accurate and easy control, and enables lean combustion while improving exhaust gas consumption while reducing exhaust emission. .

According to the tenth aspect of the present invention, the target combustion ratio used under the first operating condition is made smaller than the target combustion ratio used under the second operating condition where only the ignition timing control is carried out. It is possible to properly control the fuel supply amount and reduce exhaust emission while enabling lean combustion and improving fuel efficiency.

According to the eleventh aspect of the present invention, the combustion pressure can be detected and appropriately calculated based on the combustion pressure data.

[Brief description of drawings]

1 is a multiple cylinder spark ignition type 4 to which the present invention is applied;
It is a block diagram of a cycle engine.

FIG. 2 is a flowchart of a main routine for controlling various operating states of the engine.

FIG. 3 is a diagram showing an interrupt routine.

FIG. 4 is a diagram showing an interrupt routine.

FIG. 5 is a map diagram for obtaining a target combustion ratio according to an engine speed and a load.

FIG. 6 is a graph of combustion chamber pressure for one cycle of combustion in a four-cycle engine.

FIG. 7 is a flow chart of a lean combustion control routine when a target value is set as a combustion ratio at a predetermined crank angle.

FIG. 8 is a flow chart of a lean burn control routine in the case of having a plurality of target values as a burn rate at a predetermined crank angle.

FIG. 9 is a flowchart of ignition timing correction control when a target value is set as a combustion ratio at a predetermined crank angle.

FIG. 10 is a fuel supply amount correction routine when a correction value is calculated according to a deviation.

FIG. 11 is a diagram showing a change in a combustion ratio FMB due to an ignition timing operation.

FIG. 12 is a diagram showing a change in a combustion ratio FMB due to a fuel supply amount operation.

FIG. 13 is a graph showing a tendency of change in the combustion ratio when the fuel supply amount is changed.

FIG. 14 is a diagram showing a change in a combustion ratio FMB due to an ignition timing operation.

FIG. 15 is a graph showing changes in data when lean burn control is executed.

FIG. 16: Predetermined crank angle ATD when the A / F value is lean
It is a graph which shows the correlation of a combustion rate and HC and NOx discharge quantity at the time of C50 degrees.

FIG. 17: Predetermined crank angle ATD when the A / F value is lean
It is a graph which shows the correlation of a combustion rate and output variation at C50 °.

FIG. 18 is a map diagram for obtaining a target crank angle according to an engine speed and a load.

FIG. 19 is a graph showing the correlation between the crank angle and the HC and NOx emissions when the A / F value is lean and the combustion ratio is 70%.

FIG. 20 is a graph showing the crank angle and output variation when the A / F value is lean and the combustion ratio is 70%.

FIG. 21 is a graph of combustion chamber pressure similar to FIG. 6 of the above-described four-cycle engine for showing the combustion pressure data detection points for measuring the axial torque and the combustion ratio of the two-cycle engine.

[Explanation of symbols]

1 Engine 9 Crankshaft 10 Ring Gear 11 Crank Angle Sensor 12 Control Device 13 Combustion Chamber 25 Oxygen Concentration Sensor (O ₂ Sensor) 26 Temperature Sensor 31 Throttle Opening Sensor 32 Intake Pipe Pressure Sensor 34 Hot Wire Intake Air Volume Sensor 36 Intake Air Temperature Sensor 105 Injector 106 Regulator 120 Exhaust pipe temperature sensor 150 Catalyst temperature sensor

Continuation of front page (51) Int.Cl. ⁶ Identification number Office reference number FI Technical display location F02D 45/00 362 F02D 45/00 362B 368 368Z 376 376C F02P 5/15 F02P 5/15 B 5/152 D 5 / 153

Claims (11)

[Claims] 1. An initial value of a fuel supply amount according to at least a load, which is set so that a lean air-fuel mixture is formed in a combustion chamber when the fuel is supplied to an engine. Or has one or more combustion ratios at one or more predetermined crank angles and is stored in the memory as map data of one or more target combustion ratios corresponding to at least one of the load and the engine speed, or One or more crank angles that reach one or more predetermined combustion ratios are stored in a memory as map data of one or more target crank angles corresponding to at least one of load and engine speed. The actual combustion rate up to one or more predetermined crank angles is detected, and the detected combustion rate is based on the comparison between the detected combustion rate and the target combustion rate. Is smaller, the fuel supply amount is increased, and when the detected combustion ratio is larger, the fuel supply amount is decreased, or the actual crank angle at which one or more predetermined combustion ratios is reached is detected, Based on this comparison between the detected crank angle and the target crank angle, whether the fuel supply amount is increased when the target crank angle is ahead and the fuel supply amount is decreased when the detected value crank angle is ahead. A method for controlling an engine, comprising performing any one of fuel supply amount control. 2. A target combustion ratio having an allowable range, a first target combustion ratio larger than the target combustion ratio in the map data and a second target combustion ratio smaller than the target combustion ratio in the map data are set, and the detection is performed. When the combustion ratio is lower than the second target combustion ratio, the fuel supply amount is increased, when the detected combustion ratio is higher than the first target combustion ratio, the fuel supply amount is decreased, and the detected combustion ratio is When it is between the 1st target combustion ratio and the 2nd target combustion ratio, either the fuel supply amount is not changed, or the target crank angle is allowed to have an allowable width, and the first target crank angle advanced from the target crank angle of the map data. Horns,
A second target crank angle that is later than the target crank angle in the map data is set, and the fuel supply amount is reduced when the detected crank angle is ahead of the first target crank angle, and the detected value crank angle is Whether the fuel supply amount is increased when it is behind the second target crank angle, and the fuel supply amount is not changed when the detected crank angle is between the first target crank angle and the second target crank angle. The engine control method according to claim 1, wherein any one of the fuel supply amount controls is executed. 3. The fuel supply amount control according to claim 1, wherein at least one of a load smaller than a predetermined value and an engine speed smaller than a predetermined value is executed. 2. The engine control method described in 2. 4. An initial value of ignition timing corresponding to at least one of load and engine speed is stored as data,
One or a plurality of combustion ratios at one or a plurality of predetermined crank angles are stored in a memory as map data of one or a plurality of target combustion ratios corresponding to at least one of a load and an engine speed, or one or a plurality of predetermined combustion ratios. One or a plurality of crank angles that reach the combustion ratio are stored in a memory as map data of one or a plurality of target crank angles corresponding to at least one of the load and the engine speed, or one or a plurality of the predetermined crank angles. The actual combustion ratio up to the crank angle is detected, and based on the comparison between the detected combustion ratio and the target combustion ratio, the ignition timing is advanced when the detected combustion ratio is smaller, and the ignition timing when the detected combustion ratio is larger. Or the actual crank angle at which one or more of the predetermined combustion ratios is reached is detected, and the detected crank angle and the target Based on the comparison with the rank angle, advance the ignition timing when the target crank angle is ahead and delay the ignition timing when the detected value crank angle is ahead. The engine control method according to any one of claims 1 to 3, characterized in that. 5. The ignition timing control and the fuel supply amount control based on the detected combustion ratio or the detected crank angle when the load is smaller than a predetermined value or the engine speed is smaller than a predetermined value. While carrying out
5. The engine control method according to claim 4, wherein only the ignition timing control based on the combustion ratio is executed when the load or the engine speed is not in the condition. 6. The engine control method according to claim 4, wherein the ignition timing control and the fuel supply amount control are alternately performed. 7. The engine control method according to claim 4, wherein the ignition timing control of the first predetermined number of times and the fuel supply amount control of the second predetermined number of times are alternately performed. 8. The engine control method according to claim 7, wherein the first predetermined number of times is equal to or greater than the second predetermined number of times. 9. An initial value of a fuel supply amount according to at least a load, which is set so that a lean air-fuel mixture is formed in a combustion chamber when the fuel is supplied to an engine, and the engine load decreases as the engine load decreases. 9. The engine control method according to claim 1, further comprising data of an initial value of a fuel supply amount set so that the air-fuel ratio of the lean air-fuel mixture can be increased. 10. An ignition timing control based on the detected combustion ratio or the detected crank angle and the fuel supply amount control are performed, and at least the load is smaller than a predetermined value or the engine speed is smaller than a predetermined value. One of the target combustion ratios used under the first operating condition is made smaller than the target combustion ratio used under the second operating condition in which only the ignition timing control based on the detected combustion ratio or the detected crank angle is executed. Claim 5 thru | or Claim 8 characterized by the above.
The engine control method according to any one of 1. 11. The detected combustion ratio or the detected crank angle is a crank angle from the end of an exhaust stroke to the beginning of a compression stroke and a crank angle from the start of the compression stroke to ignition.
The combustion pressure at at least four crank angles consisting of two crank angles within the period from the start of ignition to the start of the exhaust stroke is detected and calculated based on these combustion pressure data. To claim 1
The engine control method according to any one of 0.