JP2611473B2 - Fuel injection amount control device for internal combustion engine - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection amount control device for an internal combustion engine, and more specifically, a predetermined amount of asynchronous injection in addition to synchronous injection in each cylinder in accordance with the start of acceleration of the internal combustion engine. The present invention relates to a fuel injection amount control device for an internal combustion engine that performs injection.

2. Description of the Related Art Conventionally, as a fuel injection amount control of an internal combustion engine, it has been proposed to execute a predetermined amount of asynchronous injection during normal acceleration or during acceleration from a fuel cut state.

For example, in Japanese Unexamined Patent Publication No. 60-201046, when acceleration is detected from an operation state by normal synchronous injection, asynchronous injection is executed only for the cylinder at the crank position until the end of the intake stroke after synchronous injection. And supplied fuel to prevent acceleration shock.

[Problems to be Solved by the Invention] However, in the case of the conventional example, the amount of fuel actually sucked into the combustion chamber out of the fuel injected asynchronously as the intake stroke at the start of acceleration approaches the end is reduced. Had become.

That is, as shown in FIG. 7 (a), when acceleration is started immediately before or immediately after the intake valve is opened and asynchronous injection is performed, all of the injected fuel amount at that time is stored in the combustion chamber. After being inhaled, it is subjected to explosion and combustion without excess or shortage, and acceleration shock can be prevented. However, the seventh
When asynchronous injection is performed after a while after the intake valve is opened as shown in FIG. (B), or when asynchronous injection is performed just before the intake valve is closed as shown in FIG. However, since all of the injected fuel amount at that time is not sucked into the combustion chamber, there is a possibility that it is not possible to cope with the acceleration shock despite the asynchronous injection.

This is due to the fact that a fixed amount of asynchronous injection was always performed regardless of the late or early asynchronous injection timing during the intake stroke, and the leaner the air-fuel ratio becomes as the asynchronous injection timing approaches the end of the intake stroke. It was due to

The present invention has been made in view of the above-described circumstances, and an object of the present invention is to stably prevent acceleration shock caused by asynchronous injection in accordance with late and early asynchronous injection timing during an intake stroke. An object of the present invention is to provide a fuel injection amount control device for an internal combustion engine.

[Means for Solving the Problems] In order to achieve the above object, according to the present invention, as shown in FIG. 1, fuel injection means M2 provided in each cylinder of the internal combustion engine M1, The operating state detecting means M3 for detecting the operating state, the acceleration start determining means M4 for determining the start of acceleration of the internal combustion engine M1 based on the detection value of the operating state detecting means M3, and the internal combustion engine M1 by the acceleration start determining means M4 An asynchronous injection control means M5 for controlling each fuel injection means M2 in order to perform a predetermined amount of asynchronous injection in addition to synchronous injection in each cylinder in accordance with the start of acceleration. Crank position detecting means for detecting a crank position of the internal combustion engine M1 in the fuel injection amount control device for the engine
M6 and an asynchronous injection timing determining means for determining the asynchronous injection timing during the intake stroke of each cylinder based on the detected value of the crank position detecting means M6 when the acceleration start determining means M4 determines that the internal combustion engine M1 has started to accelerate. M7 and the asynchronous injection amount from each fuel injection means M2 under the control of the asynchronous injection control means M5 corresponding to the determination result of the asynchronous injection timing determination means M7 are increased in the latter half of the intake stroke. And an asynchronous injection amount correcting means M8 for correcting so as to be suppressed immediately before the end of the stroke.

[Operation] According to the present invention, as shown in FIG.
During operation, the operating state detecting means M3 detects the operating state of the internal combustion engine M1, and the acceleration start determining means M4 determines whether or not the internal combustion engine M1 has started accelerating based on the detection value of the operating state detecting means M3. Judge. Then, the acceleration start determining means M4
When it is determined that acceleration of the internal combustion engine M1 is started,
The asynchronous injection control means M5 controls each fuel injection means M2 in order to perform a predetermined amount of asynchronous injection in addition to simultaneous injection in each cylinder in accordance with the start of acceleration.

At this time, the crank position detecting means M6 detects a periodically changing crank position during the operation of the internal combustion engine M1, and the asynchronous injection timing determining means M7 detects the crank position detecting means M6.
, The asynchronous injection timing during the intake stroke of each cylinder is determined. That is, it is determined at which time during the intake stroke the asynchronous injection is being performed.

Then, the asynchronous injection amount correcting means M8 responds to the determination result of the asynchronous injection timing determining means M7, that is, in response to the late and early asynchronous injection timing during the intake stroke, and controls each fuel under the control of the asynchronous injection control means M5. The asynchronous injection amount from the injection means M2 is corrected.

Therefore, the asynchronous injection amount is adjusted according to the late and early asynchronous injection timing, and a sufficient amount of fuel is sucked into the combustion chamber corresponding to the timing.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 2 is a diagram showing a schematic configuration of a gasoline engine system to which a fuel injection amount control device for an internal combustion engine according to the present invention is applied. The engine 1 as an internal combustion engine takes in outside air from an air cleaner 3 through an intake passage 2. Simultaneously with the intake of the outside air, the engine 1 closes each cylinder (in this case, cylinder # 1, cylinder # 2, cylinder # 3, cylinder # 3) near the intake port 1a.
The fuel injected from the injector 4 as fuel injection means provided for each of the cylinders # 4 (a total of four cylinders) is taken in.
Then, the mixture of the taken fuel and the outside air is transferred to each cylinder # 1.
To # 4, is introduced into the combustion chamber 1b through an intake valve 5a, and is exploded and burned in the combustion chamber 1b to obtain a driving force. Then, the exhaust gas is passed through an exhaust valve 5b. Each cylinder # 1
To # 4, and are discharged to the outside through an exhaust passage 6 where exhaust manifolds gather.

A throttle valve 7 that is opened and closed in conjunction with operation of an accelerator pedal (not shown) is provided in the middle of the intake passage 2. By opening and closing the throttle valve 7, the amount of air taken into the intake passage 2 is adjusted. Further, a surge tank 8 for smoothing the pulsation of the intake air is provided downstream of the throttle valve 7.

An intake air temperature sensor 21 for detecting an intake air temperature is provided near the air cleaner 3 in the intake passage 2. or,
In the vicinity of the throttle valve 7, a throttle sensor 22 for detecting the opening degree is provided. Further, the surge tank 8 communicates with the tank 8 and has a suction pressure (intake pressure) PM
Is provided. And
In this embodiment, an operating state detecting means for detecting an operating state of the engine 1 is constituted by the throttle sensor 22 and the intake pressure sensor 23.

On the other hand, an oxygen sensor 24 for detecting the oxygen concentration in the exhaust gas is provided in the exhaust passage 6. Also, Engine 1
Is provided with a water temperature sensor 25 for detecting the temperature of the cooling water.

An ignition signal distributed by a distributor 10 is applied to an ignition plug 9 provided for each of the cylinders # 1 to # 4 of the engine 1. Distributor 10 is an igniter
The high voltage output from the ignition plug 11 is distributed to the ignition plugs 9 in synchronization with the crank angle of the engine 1. The ignition timing of each ignition plug 9 is determined by the high voltage output timing from the igniter 11. .

Distributor 10 has the same distributor 10
A rotation speed sensor 26 for detecting the rotation speed NE of the engine 1 (engine rotation speed) NE from the rotation of a rotor (not shown), and a crank for detecting a change in the crank angle of the engine 1 at a predetermined rate according to the rotation of the rotor. A cylinder discriminating sensor 27 as a position detecting means is attached to each. In this embodiment, the cylinder discriminating sensor 27 detects the crank angle at a rate of 30 CA assuming that the engine 1 makes two revolutions per stroke.

Each of the injectors 4 and the igniter 11 is electrically connected to an electronic control unit (hereinafter simply referred to as “ECU”) 28 as acceleration start determining means, asynchronous injection control means, asynchronous injection timing determining means and asynchronous injection amount correcting means. And E
The operation timing of the CU is controlled by the operation of the CU. The ECU 28 includes an intake air temperature sensor 21, a throttle sensor 22, an intake pressure sensor 23, an oxygen sensor 24, a water temperature sensor 25,
The rotation speed sensor 26 and the cylinder discrimination sensor 27 are connected respectively. Therefore, the ECU 28 suitably controls the injector 4 and the igniter 11 based on the output signals from these sensors 21 to 27.

Next, the configuration of the ECU 28 will be described with reference to the block diagram of FIG. The ECU 28 includes a central processing unit (CPU) 31, a read-only memory (ROM) 32 in which a predetermined control program and the like are stored in advance, a random access memory (RAM) 33 in which a calculation result of the CPU 31 and the like are temporarily stored, and data stored in advance. It is configured as a logical operation circuit in which a backup RAM 34 and the like to be stored, and these units, an external input circuit 35, an external output circuit 36 and the like are connected by a bus 37.

The external input circuit 35 is connected to the above-described intake temperature sensor 21, throttle sensor 22, intake pressure sensor 23, oxygen sensor 24, water temperature sensor 25, rotation speed sensor 26, cylinder discrimination sensor 27, and the like. Then, the CPU 31 is connected to the external input circuit 3
The signals output from the respective sensors 21 to 27 via 5 are read as input values.

Further, the CPU 31 outputs the external output circuit 3 based on these input values.
The injector 4 and the igniter 11 connected to 6 are suitably controlled.

Next, of the fuel injection amount control executed by the ECU 28, the control processing of the asynchronous injection will be described with reference to the flowchart of FIG. This flowchart shows a routine for asynchronous injection amount control performed during the operation of the engine 1 among various processes executed by the ECU 28, and is executed by a periodic interruption at predetermined time intervals.

When the processing shifts to this routine, first, step 101
In, it is determined whether or not acceleration has started. That is, the detected values from the throttle sensor 22 and the intake pressure sensor 23 are read, and the throttle change amount Δ is determined based on the read values.
TA and the intake pressure change amount ΔPM are calculated, and the start of rapid acceleration, re-acceleration, etc., is determined based on the magnitude of the calculation result. If the acceleration is not started, there is no need to execute the asynchronous injection, so the subsequent processing is temporarily terminated.
On the other hand, if acceleration is to be started, the process proceeds to the next step 102 to execute asynchronous injection.

Then, in step 102, an asynchronous injection amount for executing the asynchronous injection, that is, an asynchronous injection time is determined. The asynchronous injection time is a time that is determined in advance depending on whether the acceleration is a re-acceleration after the fuel cut operation or another acceleration.

Next, in step 103, the current crank position is determined. That is, the detection value from the cylinder determination sensor 27 is read, and the current crank angle (position) is calculated based on the read value.

Subsequently, in step 104, a correction coefficient for the asynchronous injection time is retrieved from the map shown in FIG. 5 based on the crank angle determined in step 103. In this map, a correction coefficient for a crank angle corresponding to a period during which the intake valves 5a of the cylinders # 1 to # 4 are open, that is, an intake stroke of each of the cylinders # 1 to # 4 is determined in advance. #
The correction coefficient is set to be gradually increased from the latter half of the intake strokes 1 to # 4, and then set to be gradually reduced as the intake stroke approaches the end, and is stored in advance in the ROM 32. is there.

Further, in step 105, a corrected asynchronous injection amount (corrected asynchronous injection time) is calculated from the asynchronous injection amount determined in step 102, that is, the asynchronous injection time, and the correction coefficient searched in step 104.

Then, in step 106, based on the corrected asynchronous injection time calculated in step 105, all cylinders # 1 to # 4
Of the injectors 4 at the same time, that is, all the cylinders # 1
Asynchronous injection is performed by simultaneous injection of # 4 to # 4, and the subsequent processing is temporarily terminated.

Therefore, when asynchronous injection is executed in response to sudden acceleration and re-acceleration during operation of the engine 1, for example, FIG.
As shown in FIG.
In the case where the crank angle is immediately before or immediately after the intake valve 5a is opened, the non-synchronous injection time t1 at that time remains the standard time, and all the injected fuel is supplied to the combustion chamber 1b without excess or shortage. It is inhaled and used for explosion and combustion to prevent acceleration shock.

On the other hand, as shown in FIG. 6 (b), when the asynchronous injection timing is a certain time after the intake valves 5a of the cylinders # 1 to # 4 are opened, the asynchronous injection time at that time ends the intake stroke. , The amount of fuel sucked into the combustion chamber 1b can be increased, and sufficient fuel can be exploded and burned.

Also, as shown in FIG. 3C, when the asynchronous injection period t3 is just before the intake valves 5a of the cylinders # 1 to # 4 are closed, the asynchronous injection time t3 becomes shorter than t2. This is to suppress the increase of the asynchronous injection amount immediately before the end of the intake stroke in accordance with the correction map of the asynchronous injection amount shown in FIG.

Incidentally, the correction map of the asynchronous injection amount shown in FIG. 5 is set as follows. That is, when asynchronous injection is performed simultaneously in all cylinders # 1 to # 4, in cylinders not corresponding to the intake stroke, the air-fuel ratio becomes over-rich in subsequent intake strokes, and the driver viability deteriorates. Therefore, the correction map is set in consideration of a compromise with the occurrence of the acceleration shock due to the lean air-fuel ratio.

Therefore, it is possible to more appropriately prevent the acceleration shock in the asynchronous injection.

That is, in this embodiment, unlike the conventional example in which a fixed amount of asynchronous injection is always performed regardless of whether the asynchronous injection time during the intake stroke is late or early, the asynchronous injection time t1 to t2 decreases as the intake stroke ends. become longer. That is, the asynchronous injection amount increases, the asynchronous injection is performed until the intake valve 5a is closed, and a sufficient amount of fuel can be supplied to the fuel chamber 1b, so that the air-fuel ratio can be made lean.
In addition, immediately before the end of the intake stroke, the increase in the asynchronous injection amount is suppressed, so that the air-fuel ratio can be prevented from being over-rich and unnecessary fuel injection can be prevented. As a result, it is possible to always reliably and stably prevent the acceleration shock due to the asynchronous injection at the same time as the late asynchronous injection timing during the intake stroke.

The present invention is not limited to the above-described embodiment, and may be implemented as follows by appropriately changing a part of the configuration without departing from the spirit of the invention.

(1) In the above embodiment, when starting acceleration, all cylinders # 1 to # 1
In the case where asynchronous injection is performed simultaneously in # 4, the present invention is embodied in a case where only the cylinders in which the intake stroke is performed at the start of acceleration are specified and only the specified cylinders are independently subjected to asynchronous injection. Is also good.

(2) In the above embodiment, the acceleration start is determined based on the detection values from the throttle sensor 22 and the intake pressure sensor 23. However, the acceleration is determined based on the detection value of only one of the throttle sensor 22 and the intake pressure sensor 23. The start may be determined.

[Effects of the Invention] As described above in detail, according to the present invention, when the acceleration start judging means judges that the internal combustion engine is to start accelerating, the asynchronous injection timing judging means judges each of the values based on the detection value of the crank position detecting means. Asynchronous injection timing during the intake stroke of the cylinder is determined, and in response to the determination result, the asynchronous injection amount correction means increases the asynchronous injection amount from each fuel injection means under the control of the asynchronous injection control means in the latter half of the intake stroke. In addition, since the increase is suppressed so that the increase is suppressed immediately before the end of the intake stroke, the asynchronous injection amount can be adjusted according to the late and early asynchronous injection timing during the intake stroke. In addition, it is possible to stably prevent the fuel injection and to prevent wasteful fuel injection.

[Brief description of the drawings]

FIG. 1 is a diagram showing a basic configuration of the present invention, and FIGS.
The figure is a diagram showing one embodiment of the present invention,
FIG. 2 is a diagram showing a schematic configuration of a gasoline engine system to which a fuel injection amount control device for an internal combustion engine is applied, FIG. 3 is a block diagram showing an electric configuration of the fuel injection amount control device,
FIG. 4 is a flowchart for explaining a control process of asynchronous injection executed by the fuel injection amount control device, FIG. 5 is a map showing a correction coefficient for a crank angle corresponding to an intake stroke of each cylinder, and FIG. It is a time chart explaining the difference of the asynchronous injection time with respect to the asynchronous injection timing. Seventh
The figure is a time chart for explaining the asynchronous injection time with respect to the asynchronous injection timing in the conventional example. In the figure, M1 is an internal combustion engine, M2 is a fuel injection means, M3 is an operating state detection means, M4 is an acceleration start determination means, M5 is an asynchronous injection control means, M6 is a crank position detection means, M7 is an asynchronous injection timing determination means, M8 is an asynchronous injection amount correction means, 1 is an engine as an internal combustion engine, 4 is an injector as fuel injection means, 22 is a throttle sensor, and 23 is an intake pressure sensor (22, 23
Represents an operating state detecting means), 27 represents a cylinder discriminating sensor as a crank position detecting means, 28 represents an acceleration start determining means, an asynchronous injection control means, an asynchronous injection timing determining means, and an asynchronous injection amount correcting means. ECUs # 1 to # 4 are cylinders.

Claims (1)

(57) [Claims] A fuel injection means provided in each cylinder of the internal combustion engine; an operation state detection means for detecting an operation state of the internal combustion engine; and an acceleration of the internal combustion engine based on a detection value of the operation state detection means. Acceleration start determining means for determining start; and when the acceleration start determining means determines that acceleration of the internal combustion engine is to be started, a predetermined amount of asynchronous injection is performed in addition to synchronous injection in each of the cylinders in accordance with the start of acceleration. A fuel injection control device for an internal combustion engine, comprising: an asynchronous injection control device for controlling each of the fuel injection devices; a crank position detection device for detecting a crank position of the internal combustion engine; When it is determined that the acceleration of the engine has started, the asynchronous injection timing during the intake stroke of each of the cylinders is determined based on the value detected by the crank position detecting means. Injection timing determining means, and in response to the determination result of the asynchronous injection timing determining means, increasing the asynchronous injection amount from each of the fuel injection means under the control of the asynchronous injection control means in the latter half of the intake stroke. And a non-synchronous injection amount correcting means for correcting so as to suppress the pressure immediately before the end of the intake stroke.