JPH06200814A - Fuel control device of engine - Google Patents

Abstract

PURPOSE:To control the air-fuel ratio accurately according to the operating condition of an engine by calculating the fuel injection amount depending on the engine operating condition including the suction air amount by the first and the second timings respectively. CONSTITUTION:An injector 12 is provided by facing a suction passage 8 communicating to the combustion chamber 6 of an engine 1, and an electronic control type control unit (ECU) 20 to control the fuel injection amount from the injector 12 is provided. In the first timing prior to communicating the suction passage 8 and the combustion chamber 6, and in the second timing in the suction stroke when the suction passage 8 and the combustion chamber 6 are communicated, the fuel injection amounts are calculated depending oh the operating condition of the engine 1 respectively. And the fuel injection amount by the first timing is corrected to make in a specific divided ratio, and the fuel injection is carried out. In this case, the fuel amount subtracting the fuel injecting amount by the first timing from the fuel injecting amount by the second timing is to be injected in the second timing. As a result, the fuel to which the increase amount of the suction air amount is almost reflected is fed to the combustion chamber 6, and the control accuracy of the air-fuel ratio in a transient operation time is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel control system for an engine, and more particularly to the timing before the intake passage communicates with the combustion chamber and the timing when the intake passage communicates with the combustion chamber for each combustion cycle of the engine. And a fuel control device for an engine configured to inject fuel into the intake passage by dividing the fuel injection means.

[0002]

2. Description of the Related Art In recent years, in engines for automobiles and the like, fuel is burned in a state where the air-fuel ratio is larger than the theoretical air-fuel ratio (air / fuel = 14.7) for the purpose of improving fuel efficiency and exhaust performance. Although a lean combustion method has been attempted, stratified charge air is used as a method for stably realizing the lean combustion. This is because, by devising the fuel supply method and the shape around the combustion chamber, a rich air-fuel mixture is concentrated in the vicinity of the spark plug while the remaining fuel is lean (lean). ) To form a lean mixture, the flame generated in the rich mixture near the spark plug propagates into the surrounding lean mixture, so that the combustion chamber as a whole does not lose its combustibility. It is possible to set the air-fuel ratio of the air-fuel mixture to a lean state, and it is expected that the fuel consumption will be significantly reduced.

As a means for easily realizing this stratified air supply, for example, there is a split injection as disclosed in Japanese Utility Model Laid-Open No. 61-76143. For example, an injector for fuel injection is installed facing the intake passage leading to the combustion chamber of a reciprocating gasoline engine, and the fuel injection amount calculated based on the engine load is set to 1 for each cylinder.
A configuration in which injection is divided and supplied from the injector for each combustion cycle at a predetermined time before the intake valve opens and a predetermined time during the intake stroke when the intake valve is open Thus, the fuel injected prior to the opening of the intake valve forms a premixed air-fuel mixture in which the fuel and air are premixed in the intake passage, so that the intake valve opens. Sometimes it flows all at once into the combustion chamber,
A lean air-fuel mixture region having a lean air-fuel ratio is formed in the outer peripheral portion of the combustion chamber or cylinder. Then, the subsequent fuel injected in the intake stroke forms a rich air-fuel mixture region having a rich air-fuel ratio, for example, in the vicinity of the spark plug installed in the center of the combustion chamber. This makes it possible to concentrate the rich air-fuel mixture in the vicinity of the spark plug while keeping the air-fuel ratio of the air-fuel mixture in the combustion chamber as a whole lean.

[0004]

However, the conventional technique described in the above publication has a problem that the control accuracy of the air-fuel ratio is insufficient during transient operation of the engine such as during acceleration. That is, in the above technology,
The fuel injection amount (hereinafter referred to as the leading injection amount) at the timing before the intake valve opens (hereinafter referred to as the first timing) and the timing during the intake stroke (hereinafter referred to as the second timing).
The fuel injection amount at the timing (hereinafter referred to as the trailing injection amount) is determined by distributing the fuel injection amount calculated based on the operating state of the engine at the first timing according to a predetermined division ratio. It has become. Therefore, for example, if the engine in the steady state at the first timing shifts to the acceleration state by, for example, depressing the accelerator pedal before the second timing comes, the trailing injection amount at the second timing is approximately the first amount. It is a value obtained by subtracting the leading injection amount from the base fuel injection amount calculated at the timing. For this reason, the total fuel injection amount does not change from the steady state even though the opening degree of the throttle valve of the engine is increased and the intake air amount is increased. As a result, the air-fuel ratio becomes leaner than the target air-fuel ratio and the air-fuel ratio control accuracy deteriorates.

According to the present invention, in each combustion cycle of the engine, fuel is introduced into the intake passage by dividing the timing before the intake passage communicates with the combustion chamber and the timing before the intake passage communicates with the combustion chamber. The present invention addresses the above problems in a fuel control device for an engine configured to inject fuel, and aims to appropriately control the air-fuel ratio according to the operating state of the engine.

[0006]

That is, a fuel control device for an engine according to the invention of claim 1 of the present application (hereinafter referred to as the first invention) includes a fuel injection means installed facing an intake passage, In each combustion cycle, the fuel injection means is divided into a first timing before the intake passage communicates with the combustion chamber and a second timing during the intake stroke where the intake passage communicates with the combustion chamber. In an engine configured to inject fuel by means of fuel injection amount calculation means for calculating a fuel injection amount based on the operating state of the engine including the intake air amount at the first and second timings respectively;
At a first timing, a division ratio setting means for setting a division ratio of the fuel injection amount at both timings, and at the first timing, the fuel corrected so that the fuel injection amount calculated at the first timing becomes a ratio according to the division ratio. The first to be jetted
An injection control means and a second injection control means for injecting at the second timing an amount of fuel obtained by subtracting the fuel injection amount injected at the first timing from the fuel injection amount calculated at the second timing are provided. It is characterized by

The fuel control device for an engine according to the invention of claim 2 of the present application (hereinafter referred to as the second invention) includes fuel injection means installed so as to face the intake passage, and for each combustion cycle of the engine. , The fuel is divided from the fuel injection means at a first timing before the intake passage communicates with the combustion chamber and a second timing set in the latter half of the intake stroke where the intake passage communicates with the combustion chamber. In an engine configured to inject fuel, fuel injection amount calculation means for calculating the fuel injection amount based on the operating state of the engine including the intake air amount at the first and second timings, and the fuel injection at both timings. A dividing ratio setting means for setting a dividing ratio of the quantity; and fuel for correcting the fuel injection amount calculated at the first timing to a ratio according to the dividing ratio. A first injection control means for injecting at first timing, the second to inject fuel in an amount obtained by subtracting the fuel injection amount injected in the first timing from the fuel injection amount calculated in the second timing in the second timing
An injection control means is provided.

The invention of claim 3 of the present application (hereinafter, referred to as the third
The fuel control device for an engine according to the invention includes a fuel injection unit installed facing the intake passage, and the first timing before the intake passage communicates with the combustion chamber for each combustion cycle of the engine, In the engine configured to inject fuel separately from the fuel injection means at the second timing set in the latter half of the intake stroke in which the intake passage communicates with the combustion chamber, Fuel injection amount calculation means for calculating the fuel injection amount based on the operating state of the engine including the intake air amount at each timing, division ratio setting means for setting the division ratio of the fuel injection amounts at both timings, and the first timing. The first injection control means for injecting fuel at the first timing, the fuel having been corrected so that the fuel injection amount calculated in step 3 has a ratio according to the above-mentioned division ratio; Second injection control means for injecting the fuel at the second timing with an amount of fuel obtained by subtracting the fuel injection amount injected at the first timing from the fuel injection amount calculated at the timing, and an acceleration state detection for detecting an acceleration state of the engine. Means and a division ratio correction means for increasing the division ratio of the fuel injection amount at the first timing when the acceleration state of the engine is detected by the detection means.

Further, an engine fuel control apparatus according to a fourth aspect of the present invention (hereinafter referred to as a fourth invention) is provided with fuel injection means installed so as to face the intake passage, and for each combustion cycle of the engine. , The fuel is divided from the fuel injection means at a first timing before the intake passage communicates with the combustion chamber and a second timing set in the latter half of the intake stroke where the intake passage communicates with the combustion chamber. In an engine configured to inject fuel, a fuel injection amount calculating means for calculating a fuel injection amount based on an operating state of the engine including the intake air amount at the first and second timings, and an engine load are detected. The engine load detecting means, and the first, depending on the engine load detected by the detecting means.
A division ratio setting means for setting a division ratio of the fuel injection amount at the second timing, and a fuel corrected so that the fuel injection amount calculated at the first timing becomes a ratio according to the division ratio is at the first timing. And a second injection control for injecting the fuel in an amount obtained by subtracting the fuel injection amount injected at the first timing from the fuel injection amount calculated at the second timing at the second timing. Means, acceleration state detection means for detecting the acceleration state of the engine, and division ratio correction means for increasing the division ratio of the fuel injection amount at the first timing when the acceleration state of the engine is detected by the detection means. It is characterized by being provided.

Further, in the engine fuel control apparatus according to the invention of claim 5 of the present application (hereinafter referred to as the fifth invention), the division ratio correction means in the third and fourth inventions is used as the engine acceleration is larger. It is characterized in that the division ratio is increased at the first timing.

[0011]

According to the above construction, the following operation can be obtained.

First, according to the first aspect of the present invention, there are a first timing before the intake passage and the combustion chamber communicate with each other and a second timing during the intake stroke when the intake passage and the combustion chamber communicate with each other.
Since the fuel injection amount is calculated based on the operating state of each engine, for example, the engine in the steady state at the first timing is brought into the acceleration state by, for example, depressing the accelerator pedal before the second timing comes. Even if the transition is made, when the second timing arrives, the fuel injection amount that reflects the latest operating state at that time is calculated. In that case, the fuel, which is obtained by correcting the fuel injection amount calculated at the first timing to be a ratio according to a predetermined division ratio, is injected at the first timing and is calculated at the second timing. Since the amount of fuel obtained by subtracting the fuel injection amount injected at the first timing from the fuel injection amount is injected at the second timing, the fuel that substantially reflects the increase amount of the intake air is the combustion chamber. Will be supplied to
The accuracy of controlling the air-fuel ratio during the transient operation is improved.

Further, in a steady state in which the intake air amount hardly changes at the first and second timings, the fuel injection amounts calculated at the respective timings are substantially equal, so that the fuel actually injected at the second timing is injected. The injection amount also reflects the above division ratio. As a result, the control accuracy of the air-fuel ratio in the steady state is not deteriorated.

Further, according to the second aspect of the invention, the above operation can be obtained in the engine in which the second timing in the split injection is set in the latter half of the intake stroke, so that the control accuracy of the air-fuel ratio during steady operation can be improved. It is possible to further improve the control accuracy of the air-fuel ratio during the transient operation without deteriorating.

On the other hand, according to the third and fourth inventions, the second
In the engine whose timing is set in the latter half of the intake stroke, when the acceleration state of the engine is detected, the first
Since the division ratio of the fuel injection amount at the timing is increased, the division ratio of the second timing in the normal time is set to be large in order to form the rich air-fuel mixture in the vicinity of the spark plug well and improve the combustion stability. In addition, it is possible to avoid the over lean state of the air-fuel ratio at the time of acceleration and prevent the deterioration of the combustibility.

In other words, in this type of split injection, the stratification degree of the air-fuel mixture in the combustion chamber increases as the proportion of trailing injection is increased, and a rich air-fuel mixture is efficiently formed in the vicinity of the spark plug and lean. Combustion stability in combustion will be improved.

However, if the first timing comes immediately after the accelerator pedal is depressed for acceleration, for example, the change in the opening of the throttle valve interlocked with the accelerator pedal is small and the amount of air taken into the engine is also small. Since there is almost no change, the base fuel injection amount at that time does not change much from the previous state. If the second timing comes after the accelerator operation, the amount of air corresponding to the throttle opening at that time has been sucked into the engine, so that the fuel injection amount that is the base of the trailing injection also increases. here,
The sharing ratio between leading injection and trailing injection is
If the ratio is set so that the trailing injection is emphasized, the amount of fuel to be injected in the latter half of the intake stroke is further increased because the leading injection amount is almost the same as in the steady state. Therefore, before the entire amount of fuel injected in the latter half of the intake stroke is sucked into the combustion chamber, the communication between the intake passage and the combustion chamber is cut off, and the air-fuel mixture in the combustion chamber becomes over lean, causing misfire. It becomes easy and the flammability is deteriorated.

However, according to the third and fourth aspects of the invention, as described above, the division ratio at the first timing is increased when the engine is in the accelerated state.
The fuel injection amount at the second timing becomes small, and therefore the total amount of fuel injected at the first and second timings is supplied to the combustion chamber, so that the over lean state of the air-fuel ratio is avoided and the combustibility is improved. Will be prevented from worsening.

Further, according to the fourth aspect of the invention, the division ratios of the first and second timings are set according to the engine load, so that the division ratio of the second timing is large and high when the load is low, for example. It is possible to set the division ratio such that the division ratio of the first timing is large when the load is applied. As a result, when the load is low, it becomes possible to increase the fuel injection amount in the latter half of the intake stroke to strengthen the stratification degree and efficiently form a rich air-fuel mixture in the vicinity of the spark plug, and to perform lean combustion satisfactorily. At high load, the fuel injection amount in the latter half of the intake stroke is reduced to avoid excessive concentration of rich air-fuel mixture in the vicinity of the spark plug, and to prevent a large amount of NOx due to too good combustibility. It is also possible.

According to the fifth aspect of the invention, the division ratio at the first timing is increased in accordance with the degree of acceleration of the engine, so that the air-fuel ratio in divided injection can be controlled more appropriately.

[0021]

EXAMPLES Examples of the present invention applied to a reciprocating gasoline engine will be described below.

As shown in FIG. 1, the engine 1 has an inner peripheral surface of a cylinder bore 3 formed in a cylinder block 2,
A combustion chamber 6 formed by an upper surface of a piston 4 slidably fitted in the cylinder bore 3 and a bottom surface of a cylinder head 5 installed on an upper portion of the cylinder block 2 is provided, and the cylinder head 5 is provided. The intake passage 8 communicating with the combustion chamber 6 via the intake valve 7 installed in the
Air cleaner 9 for filtering the air taken into the engine 1
An air flow sensor 10 for detecting the intake air amount, a throttle valve 11 for adjusting the intake air amount or the engine output, and an injector 12 for fuel injection are installed. The injector 12 is installed immediately upstream of the intake valve 7 so that the extension line of the nozzle thereof passes through the opening to the combustion chamber 6 opened and closed by the intake valve 7 and points toward the center of the combustion chamber. .

On the other hand, an ignition plug 14 is installed between the exhaust valve 13 mounted on the cylinder head 5 and the intake valve 7 with the ignition part at the tip exposed inside the combustion chamber 6. A catalytic converter 16 that purifies exhaust gas is installed in an exhaust passage 15 that communicates with the combustion chamber 6 through the exhaust valve 13.

The engine 1 is equipped with an electronically controlled control unit (hereinafter referred to as ECU) 20 for controlling the fuel injection amount from the injector 12. The ECU 20 uses the air flow sensor 1 described above.
The air amount signal from 0, the throttle opening signal from the throttle opening sensor 21 that detects the opening of the throttle valve 11, the water temperature signal from the water temperature sensor 22 that detects the cooling water temperature of the engine 1, and the crank angle. By inputting the TDC signal indicating the top dead center position of the piston 4 output from the sensor 23 and the engine speed signal, and controlling the operation of the injector 12 based on these signals, each combustion cycle of the engine 1 In addition, the split injection control is performed in which the fuel is divided and injected at the first timing before the intake valve 7 is opened and the second timing during the intake stroke when the intake valve 7 is opened. There is.

In this embodiment, the second timing is set in the latter half of the intake stroke (for example, a position that is delayed by 90 ° from the exhaust top dead center in the crank angle), and the first timing is the first timing. It is set to a position that is 360 degrees ahead of the two timings in crank angle.

Next, the split injection control according to this embodiment will be described. Specifically, the split injection control is performed as follows according to the flowchart of FIG.

That is, the ECU 20 reads various signals in step S1 and then executes step S2 to execute one combustion cycle based on the intake air amount Q and the engine speed Ne indicated by the signals from the sensors 10 and 23. The amount of air taken into the combustion chamber 6, that is, the charging efficiency Ce is calculated. Then, the ECU 20 executes steps S3 and S4 to calculate the basic leading injection amount Tlo and the basic trailing injection amount Tto, respectively. That is, the ECU 2
0 is, for example, when the timing signal generated based on the TDC signal from the crank angle sensor 23 indicates the first timing, the basic injection amount for realizing the target air-fuel ratio is obtained from the charging efficiency Ce at that time, and the value thereof is obtained. Is corrected in accordance with the engine water temperature or the like indicated by the signal from the water temperature sensor 22 to obtain the basic leading injection amount Tlo.
Is required. When the timing signal indicates the second timing, the charging efficiency C at that time is
The basic injection amount for achieving the target air-fuel ratio is obtained from e, and the basic trailing injection amount Tto is obtained by correcting the value in accordance with the engine water temperature or the like indicated by the signal from the water temperature sensor 22. Will be done.

Next, the ECU 20 executes step S5, and as shown in FIG. 3, the actual engine speed Ne and the charging efficiency are added to the map of the basic division ratio which is set in advance with the engine speed and the charging efficiency as parameters. And Ce, and the basic division ratio Dp corresponding to the operating state at that time
Read o. In addition, as a general tendency, the map of the basic division ratio is set such that the basic division ratio Dpo becomes a value of 1 or less when the charging efficiency Ce as the representative characteristic of the engine load is small, and the charging efficiency Ce The basic division ratio Dpo is set to increase as

Further, the ECU 20 executes step S6 to calculate the charging efficiency deviation amount ΔCe. That is, the ECU 2
0 is, for example, a value obtained by subtracting the average filling efficiency Ce ′ from the actual filling efficiency Ce ′ after calculating the average filling efficiency Ce ′ by weighted averaging the previous value and the current value of the filling efficiency at a predetermined ratio. The charging efficiency deviation amount ΔCe is set. In this case, for example, at the time of acceleration, the throttle valve 11
The actual filling efficiency Ce increases rapidly with the change in the opening degree of the
Since the value is updated to reflect the previous value of e, the increase will be gradual. As a result, the charging efficiency deviation amount ΔC
It is possible to distinguish the acceleration / deceleration state and the steady operation state of the engine 1 by the size of e, and the larger the acceleration / deceleration, the larger the charging efficiency deviation amount ΔCe becomes.

Next, the ECU 20 executes step S7 to determine whether the filling efficiency deviation amount ΔCe is larger than a predetermined acceleration judgment value α, and the filling efficiency deviation amount ΔCe is judged to be the acceleration judgment value α. When it is determined that the actual engine speed Ne and the actual engine speed Ne are charged in the map of the basic division ratio correction value set in advance with the engine speed and the charging efficiency as parameters, as shown in FIG. The efficiency De is applied and the basic division ratio correction value Dmo corresponding to the operating state at that time is read. The map of the basic division ratio correction value is set so that the basic division ratio correction value Dmo gradually increases as the filling efficiency deviation amount ΔCe increases as a general tendency.

Then, step S9 is executed to calculate the final division ratio Df. That is, as shown in FIG. 5, the ECU 20 adds the basic division ratio DPo calculated in step S5 to the map of the final basic division ratio set in advance with the basic division ratio, the charging efficiency, and the engine speed as parameters.
And the charging efficiency Ce and the engine speed Ne,
The corresponding final basic division ratio Dp is read out, and as shown in FIG. 6, the map of the final division ratio correction value, which is set in advance with the basic division ratio correction value, the charging efficiency and the engine speed as parameters, is used for the step S8. The basic division ratio correction value Dmo, the charging efficiency Ce, and the engine speed Ne obtained in
And the corresponding final division ratio correction value Dm is read. Then, a value obtained by adding the final division ratio correction value Dm to the final basic division ratio Dp is set as the final division ratio Df.

Here, the map of the final basic division ratio is
As shown in FIG. 5, as the basic split ratio Dpo increases, the final basic split ratio Dp increases, and as the charging efficiency Ce increases, the final basic split ratio Dp increases, and the engine speed Ne further increases. As a result, the final basic division ratio Dp increases.

The map of the final division ratio correction value is
As shown in FIG. 5, the final division ratio correction value Dm increases as the basic division ratio correction value Dmo increases, and the charging efficiency Ce
The final division ratio correction value Dm increases as the engine speed Ne increases, and the final division ratio correction value Dm increases as the engine speed Ne increases.
It is a characteristic that m increases.

Next, the ECU 20 executes step S10, and the basic leading injection amount Tl is expressed by the following relational expression.
Substituting o and the final division ratio Dp, the calculation result is set as the final leading injection amount Tl.

Tl = Tlo × Dp ... That is, the final dividing ratio D is added to the basic leading injection amount Tlo.
The result obtained by multiplying p is set as the final leading injection amount Tl.

Further, the ECU 20 executes step S11 to calculate the basic trailing injection amount Tt according to the following relational expression.
Substituting o and the final leading injection amount Tl, the calculation result is set as the final trailing injection amount Tt.

Tt = Tto−Tl In other words, the result obtained by subtracting the final trailing injection amount Tt from the basic trailing injection amount Tto is set as the final trailing injection amount Tt.

Next, the ECU 20 executes step S12, and at the first timing, the final leading injection amount Tl
A pulsed drive signal is output to the injector 12 so that the fuel corresponding to the fuel injection amount is injected and the fuel corresponding to the final trailing injection amount Tt is injected at the second timing.

On the other hand, when the ECU 20 determines in step S7 that the charging efficiency deviation amount ΔCe is not larger than the acceleration determination value α, the process proceeds to step S13 and only the final basic division ratio map shown in FIG. 5 is displayed. The final division ratio Df corresponding to the actual charging efficiency Ce and the engine speed Ne is set by using this.

Next, the operation of the embodiment will be described.

As shown in FIG. 7, the first timing pulse and the exhaust top dead center at a predetermined timing in the latter half of the expansion stroke after a predetermined crank angle has elapsed since the TDC signal corresponding to the compression top dead center was output. The second timing pulse is output at a predetermined timing in the latter half of the intake stroke after a predetermined crank angle has elapsed since the TDC signal corresponding to the above was output, and is calculated in synchronization with these first and second timing pulses. Based on the charging efficiency Ce, the basic leading injection amount Tlo at the first timing and the basic trailing injection amount Tto at the second timing are calculated respectively.

In this case, it is assumed that the first timing pulse is generated in association with the TDC signal corresponding to the compression top dead center when the charging efficiency Ce is substantially constant as shown by the arrow (a). At this time, the engine 1 at that time
Basic leading injection quantity Tlo corresponding to the operating state of
Is set to the final leading injection amount Tl by multiplying the final dividing ratio Df obtained from the map of the final basic dividing ratio shown in FIG. 5, and the fuel corresponding to the injection amount Tl is synchronized with the first timing pulse. Then the injector 12
Will be jetted from. Then, when the second timing pulse is generated in association with the TDC signal corresponding to the exhaust top dead center, from the basic trailing injection amount Tto corresponding to the operating state of the engine 1 at that time point to the final leading injection amount Tl. Is set as the final trailing injection amount Tt, and the fuel corresponding to the injection amount Tt is injected from the injector 12 in synchronization with the second timing pulse. Here, if there is no change in the charging efficiency Ce calculated at the first and second timings, the basic leading injection amount Tlo and the basic trailing injection amount Tt calculated based on the charging efficiency Ce.
Since o is substantially equal to each other, the total amount of fuel injected at the first timing and the second timing is equivalent to the sum of the basic leading injection amount Tlo and the basic trailing injection amount Tto. As a result, in the steady state, the fuel redistributed according to the split ratio corresponding to the operating state at that time is injected at each of the first timing and the second timing, and the air-fuel ratio control accuracy is improved. It does not get worse. In that case, as described above, when the filling efficiency Ce is small, the basic division ratio Dpo is set to a value of 1 or less, and the filling efficiency Ce
Since the basic division ratio Dpo is set to increase with an increase in the fuel injection amount, the rich mixture is efficiently formed in the vicinity of the spark plug 14 at the time of the low load to perform a good lean combustion, and at the time of the high load. Excessive rich air-fuel mixture is prevented from concentrating in the vicinity of the spark plug 14, and a large amount of NOx is prevented due to too good combustibility.

On the other hand, the arrow (a) is generated by the acceleration of the engine 1.
It is assumed that the first timing pulse is generated in association with the TDC signal corresponding to the compression top dead center when the charging efficiency Ce is increasing as indicated by. At this time, when the charging efficiency deviation amount ΔCe calculated from the charging efficiency Ce and the average charging efficiency Ce ′ is larger than the acceleration determination value α, the basic leading injection amount Tlo corresponding to the operating state of the engine 1 at that time. Is multiplied by the final division ratio Df obtained from the map of the final basic division ratio shown in FIG. 5 and the map of the final division ratio correction value shown in FIG. 6 to set the final leading injection amount Tl. The fuel corresponding to Tl is injected from the injector 12 in synchronization with the first timing pulse. In that case, as described above, the basic division ratio correction value Dmo gradually increases as the charging efficiency deviation amount ΔCe representing the acceleration of the engine 1 increases, so that the final dividing ratio Vf also changes. It becomes large reflecting the amount ΔCe. As a result, if the division ratio is the same as in the steady state, the drive signal having a narrow pulse width as indicated by the chain line indicated by the arrow (c) is output at the first timing, whereas the charging efficiency deviation amount ΔCe
Accordingly, the final leading injection amount Tt increases as the final division ratio Vf increases, and a drive signal having a wide pulse width is output at the first timing as indicated by the solid line indicated by arrow (d) in the figure. It will be. Then, at the time when the second timing pulse is generated in association with the TDC signal corresponding to the exhaust top dead center, the basic trailing injection amount Tto corresponding to the operating state of the engine 1 at that time.
The value obtained by subtracting the final leading injection amount Tl from is set as the final trailing injection amount Tt, and the fuel corresponding to the injection amount Tt is injected from the injector 12 in synchronization with the second timing pulse. . In this case, since the final leading injection amount Tl is set large as described above, even if the basic trailing injection amount Tto increases as the filling efficiency Ce increases, the final trailing injection amount Tt becomes smaller. Since the pulse width of the drive signal output at the second timing is too wide as shown by the arrow (e) in the figure, the fuel injection does not end at the effective injection end angle Ao. Moreover, the air-fuel ratio is prevented from becoming over lean. Moreover, the final trailing injection amount Tt injected at the second timing is calculated based on the latest charging efficiency Ce calculated from the intake air amount at the second timing, so that the intake air amount Even if the fuel injection amount is too small with respect to the increase, deterioration of the air-fuel ratio control accuracy is avoided.

In this embodiment, the acceleration judgment is made based on the change of the charging efficiency.
Alternatively, the acceleration determination may be directly performed based on the change in the throttle opening.

The present invention can also be applied to a rotary piston engine having neither intake nor exhaust valves.

[0046]

As described above, according to the present invention, the timing before the intake passage communicates with the combustion chamber and the timing before the intake passage communicates with the combustion chamber for each combustion cycle of the engine. In an engine configured to divide and inject fuel into the intake passage, a first timing before the intake passage and the combustion chamber communicate with each other and an intake stroke during the intake stroke in which the intake passage and the combustion chamber communicate with each other Since the fuel injection amount is calculated based on the operating state of the engine at the second timing, for example, the engine in the steady state at the first timing is, for example, the accelerator pedal before the second timing arrives. Even if the acceleration state is entered by the depression operation, when the second timing comes, the fuel injection amount that reflects the latest operating state at that time is calculated. It made. In that case, the fuel, which is obtained by correcting the fuel injection amount calculated at the first timing to be a ratio according to a predetermined division ratio, is injected at the first timing and is calculated at the second timing. Since the amount of fuel obtained by subtracting the fuel injection amount injected at the first timing from the fuel injection amount is injected at the second timing, the fuel that substantially reflects the increase amount of the intake air is the combustion chamber. Therefore, the control accuracy of the air-fuel ratio during the transient operation is improved.

Further, in a steady state in which the intake air amount hardly changes at the first and second timings, the fuel injection amounts calculated at the respective timings are substantially equal, so that the fuel actually injected at the second timing is The injection amount also reflects the above division ratio. As a result, the control accuracy of the air-fuel ratio in the steady state is not deteriorated.

According to the second aspect of the invention, in the engine in which the second timing in the split injection is set in the latter half of the intake stroke, the air-fuel ratio control during the steady operation is not deteriorated and the air-fuel ratio during the transient operation is reduced. It is possible to further improve the control accuracy of the fuel ratio.

On the other hand, according to the third and fourth inventions, the second
In the engine whose timing is set in the latter half of the intake stroke, when the acceleration state of the engine is detected, the first
Since the division ratio of the fuel injection amount at the timing is increased, the division ratio of the second timing in the normal time is set to be large in order to form the rich air-fuel mixture in the vicinity of the spark plug well and improve the combustion stability. In addition, it is possible to avoid the over lean state of the air-fuel ratio at the time of acceleration and prevent the deterioration of the combustibility.

Further, according to the fourth aspect of the invention, the division ratios of the first and second timings are set according to the engine load, so that the division ratio of the second timing is large and high when the load is low, for example. It is possible to set the division ratio such that the division ratio of the first timing is large when the load is applied. As a result, when the load is low, it becomes possible to increase the fuel injection amount in the latter half of the intake stroke to strengthen the stratification degree and efficiently form a rich air-fuel mixture in the vicinity of the spark plug, and to perform lean combustion satisfactorily. At high load, the fuel injection amount in the latter half of the intake stroke is reduced to avoid excessive concentration of rich air-fuel mixture in the vicinity of the spark plug, and to prevent a large amount of NOx due to too good combustibility. It is also possible.

Further, according to the fifth aspect of the invention, since the division ratio of the first timing is increased according to the acceleration of the engine, the air-fuel ratio in the divided injection can be controlled more appropriately. .

[Brief description of drawings]

FIG. 1 is a control system diagram of an engine.

FIG. 2 is a flowchart showing divided injection control according to the embodiment.

FIG. 3 is an explanatory diagram of a map of a basic division ratio used for the control.

FIG. 4 is an explanatory diagram of a map of basic division ratio correction values used in the control.

FIG. 5 is an explanatory diagram of a map of a final basic division ratio used in the control.

FIG. 6 is an explanatory diagram of a map of final division ratio correction values used in the control.

FIG. 7 is a time chart diagram showing the operation of the embodiment.

[Explanation of symbols]

 1 Engine 6 Combustion Chamber 8 Intake Passage 10 Air Flow Sensor 12 Injector 20 ECU 23 Crank Angle Sensor

Claims (5)

[Claims] 1. A fuel injection means installed facing the intake passage, wherein the first timing before the intake passage and the combustion chamber communicate with each other in each combustion cycle of the engine, and the intake passage and the combustion chamber A fuel control device for an engine, which is configured to inject fuel by dividing it from the fuel injection means at a second timing during an intake stroke that is in communication with each other, and intake air at each of the first and second timings. Fuel injection amount calculation means for calculating the fuel injection amount based on the operating state of the engine including the amount, division ratio setting means for setting the division ratio of the fuel injection amount at both timings, and the fuel calculated at the first timing. First injection control means for injecting fuel at the first timing, the fuel having an injection amount corrected so as to have a ratio according to the division ratio, and a fuel calculated at the second timing. A fuel injection control device for an engine, comprising: a second injection control means for injecting an amount of fuel obtained by subtracting a fuel injection amount injected at a first timing from a fuel injection amount at the second timing. 2. A fuel injection means installed facing the intake passage, wherein the first timing before the intake passage and the combustion chamber communicate with each other in each combustion cycle of the engine, and the intake passage and the combustion chamber A fuel control device for an engine configured to inject fuel by splitting from the fuel injection means at a second timing set in the latter half of the communicating intake stroke, and the first and second timings. In the first timing, the fuel injection amount calculation means for calculating the fuel injection amount based on the operating state of the engine including the intake air amount, the division ratio setting means for setting the division ratio of the fuel injection amount at both timings, and First injection control means for injecting fuel, which is obtained by correcting the calculated fuel injection amount to a ratio according to the division ratio, at the first timing, and at the second timing. And a second injection control means for injecting an amount of fuel obtained by subtracting the fuel injection amount injected at the first timing from the calculated fuel injection amount at the second timing. Fuel control device. 3. A fuel injection means installed facing the intake passage, wherein the first timing before the intake passage and the combustion chamber communicate with each other in each combustion cycle of the engine, and the intake passage and the combustion chamber. A fuel control device for an engine configured to inject fuel by splitting from the fuel injection means at a second timing set in the latter half of the communicating intake stroke, and the first and second timings. In the first timing, the fuel injection amount calculation means for calculating the fuel injection amount based on the operating state of the engine including the intake air amount, the division ratio setting means for setting the division ratio of the fuel injection amount at both timings, and First injection control means for injecting fuel, which is obtained by correcting the calculated fuel injection amount to a ratio according to the division ratio, at the first timing, and at the second timing. Second injection control means for injecting an amount of fuel at the second timing by subtracting the fuel injection amount injected at the first timing from the calculated fuel injection amount, and an acceleration state detecting means for detecting an acceleration state of the engine And a division ratio correction means for increasing the division ratio of the fuel injection amount at the first timing when the acceleration state of the engine is detected by the detection means. . 4. A fuel injection means installed facing the intake passage, wherein the first timing before the intake passage and the combustion chamber communicate with each other in each combustion cycle of the engine, and the intake passage and the combustion chamber A fuel control device for an engine configured to inject fuel by splitting from the fuel injection means at a second timing set in the latter half of the communicating intake stroke, and the first and second timings. In accordance with the engine load detected by the fuel injection amount calculation means for calculating the fuel injection amount based on the operating state of the engine including the intake air amount, the engine load detection means for detecting the engine load, and the engine load detected by the detection means. A division ratio setting means for setting the division ratio of the fuel injection amount at the first and second timings, and the fuel injection amount calculated at the first timing according to the division ratio. First injection control means for injecting fuel corrected so that the ratio becomes the same, at the first timing,
Second injection control means for injecting the fuel at the second timing with an amount of fuel obtained by subtracting the fuel injection amount injected at the first timing from the fuel injection amount calculated at the second timing, and an acceleration state of the engine are detected. An engine provided with an acceleration state detection means and a division ratio correction means for increasing the division ratio of the fuel injection amount at the first timing when the acceleration state of the engine is detected by the detection means. Fuel control system. 5. The division ratio correction means is configured to increase the division ratio at the first timing as the engine acceleration degree increases.
Alternatively, the fuel control device for the engine according to claim 4.