JPH10318018A - Fuel injection control device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel injection control device capable of improving startability. SOLUTION: An engine 1 is provided with four cylinders #1 to #4. An intake port 9 communicated with each combustion chamber 7 is arranged on a cylinder head 4, and an injector 17 for supplying fuel is arranged in the vicinity of the intake port 9 per cylinder. In an electronic control device (ECU) 51, in the case where a cranking continuous time is a predetermined time or more, it is judged that the engine 1 is not started regardless that cranking is carried out for a comparatively long period, and scavenging, namely, reduction of a fuel injection rate is carried out in only the cylinders #1 and #2. In the case where the necessity for scavenging is judged, the degrees of the demand for scavenging are different from each other by various conditions. When the degree of the demand for scavenging is large, combustion is carried out in the cylinders #1 and #2 in which the injection rate is reduced. When the degree of the demand for scavenging is small, combustion is carried out in the cylinders #3 and #4 in which the injection rate is not reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection control device for an internal combustion engine, and more particularly, to a fuel injection control for an internal combustion engine for controlling the injection of fuel from a fuel injection means during cranking of the internal combustion engine. It concerns the device.

[0002]

2. Description of the Related Art Conventionally, when starting an engine in a cold state, it is common practice to increase the amount of fuel injected from an injector due to poor atomization of fuel. When starting the engine, if the cranking speed is insufficient or the cranking time is insufficient due to a decrease in the battery voltage, the engine may fail to start.

When the fuel injection amount is increased as described above, the increased amount of fuel may adhere to the inner wall of the intake pipe downstream of the injector or the inner wall of the combustion chamber. Therefore, if the start of the engine fails, the mixture in the combustion chamber becomes excessively rich (over-rich) due to the attached fuel, or the liquid fuel adheres to the ignition plug, making it impossible to generate a spark. There is a risk. In such a case, even if cranking is performed again, the engine may not be able to be started.

For this reason, a technique called "scavenging" has conventionally been proposed. For example, JP-A-53-9924
The publication discloses that when the cranking time exceeds a predetermined time, the above-described fuel increase is stopped or the fuel is reduced. Also, Japanese Unexamined Patent Publication No.
Japanese Patent No. 29422 discloses that when the cranking time exceeds a predetermined time, the fuel injection is stopped (cut). As described above, when the engine cannot be started even if the cranking is continued for a predetermined time, the excess fuel in the intake pipe or the combustion chamber is discharged by reducing the fuel injection amount or the like as compared with the normal start. Becomes Therefore, by performing such scavenging, the engine can be restarted in many cases even if the engine fails to start once.

[0005]

However, the above prior art has the following problems. That is, in the above technique, when the engine cannot be started even if the cranking is continued for a predetermined time, the fuel injection amount is uniformly reduced or cut. For this reason, scavenging may be inappropriate for the engine at that time.

More specifically, the required degree of scavenging varies depending on various factors such as the temperature of the engine at the time of starting, the degree of battery voltage shortage, and the duration of cranking. Therefore, it is very difficult to uniquely set the scavenging conditions that match all the factors. Despite this, conventionally, since the fuel injection amount has been uniformly reduced or cut, depending on the state of the engine at that time, sufficient scavenging may not be performed, or excessive scavenging may be performed. As a result, an appropriate air-fuel ratio required for starting cannot be obtained. As a result, even if the scavenging is performed, there is a possibility that restarting becomes impossible.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a fuel injection control device for an internal combustion engine that can improve the startability.

[0008]

According to one aspect of the present invention, there is provided a fuel injection device for supplying fuel to each combustion chamber of an internal combustion engine having a plurality of combustion chambers. Determining the amount of fuel injected from the fuel injection means when cranking of the internal combustion engine is being performed, and controlling the injection from the fuel injection means based on the determined fuel amount. A fuel injection amount control means, and scavenging for judging whether or not scavenging of an intake passage and a combustion chamber downstream of the fuel injection means is necessary when cranking of the internal combustion engine is performed. When the scavenging is determined to be necessary by the determining means and the scavenging determining means, the amount of fuel injected from a part of the plurality of fuel injection means is determined by the first fuel injection amount controlling means. Spent fuel Or to lose weight than, or the fuel injection control apparatus for an internal combustion engine having a second fuel injection quantity control means for zero is set to its gist.

According to a second aspect of the present invention, in the fuel injection control device for an internal combustion engine according to the first aspect, the scavenging determination means determines that a predetermined time has elapsed since the cranking of the internal combustion engine was started. However, the gist is that it is determined that scavenging is necessary when the internal combustion engine does not reach a complete explosion state.

According to a third aspect of the present invention, in the fuel injection control device for an internal combustion engine according to the first or second aspect, further, a state detecting means for detecting a state of the internal combustion engine, and the state detecting means The gist of the present invention is to provide a reduction amount adjusting means for adjusting the amount of fuel reduced by the second fuel injection amount control means on the basis of the detection result.

According to a fourth aspect of the present invention, there is provided the fuel injection control device for an internal combustion engine according to the first or second aspect, further comprising: a state detecting means for detecting a state of the internal combustion engine; The gist of the present invention is to provide a variable reduction means for varying a fuel injection means to be subjected to an injection amount reduction (including a case where the fuel amount is zero) based on a detection result of the means.

(Operation) According to the first aspect of the present invention, fuel is supplied to each combustion chamber of an internal combustion engine having a plurality of combustion chambers by the fuel injection means. Further, when cranking of the internal combustion engine is performed, the first fuel injection amount control means determines the amount of fuel injected from the fuel injection means, and based on the determined amount of fuel, The injection from the injection means is controlled.

Further, when cranking of the internal combustion engine is being performed, the scavenging determination means determines whether or not scavenging of the intake passage and the combustion chamber downstream of the fuel injection means is necessary. When the scavenging determination unit determines that scavenging is necessary, the amount of fuel injected from a part of the plurality of fuel injection units is changed by the second fuel injection amount control unit to the first fuel injection amount. The fuel amount is reduced from the fuel amount determined by the fuel injection amount control means, or set to zero.

For this reason, when it is determined that scavenging is necessary, the degree of scavenging request varies depending on various conditions, but when the degree of scavenging request is large,
Combustion occurs in the combustion chamber corresponding to the fuel injection means whose injection amount has been reduced, and when the degree of scavenging demand is small, combustion occurs in the combustion chamber corresponding to the fuel injection means whose injection amount has not been reduced. sell.

According to the second aspect of the present invention, in addition to the operation of the first aspect, even if a predetermined time has elapsed since the start of cranking of the internal combustion engine, the internal combustion engine is completed. When the explosion does not occur, the above control is performed.

Further, according to the third aspect of the present invention,
In addition to the effects of the invention described in claims 1 and 2,
The state of the internal combustion engine is detected by the state detection means, and based on the detection result, the fuel amount to be reduced by the second fuel injection amount control means is adjusted by the reduction amount adjustment means.
Therefore, in a combustion chamber or the like in which scavenging can be performed, scavenging is performed according to the state of the internal combustion engine at that time, and furthermore, the degree of scavenging request.

Further, according to the invention described in claim 4,
In addition to the effects of the invention described in claims 1 and 2,
The state of the internal combustion engine is detected by the state detecting means, and the fuel injection means to be subjected to the injection amount reduction is made variable by the reduction target variable means based on the detection result. For this reason, the number of combustion chambers in which scavenging is performed is appropriately changed according to the degree of scavenging demand, and combustion can more reliably occur in any one of the combustion chambers.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment embodying a fuel injection control device for an internal combustion engine according to the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a schematic configuration diagram showing a fuel injection control device of an engine as an internal combustion engine mounted on a vehicle in the present embodiment. The engine 1 mounted on the vehicle includes a plurality of cylinders (in this embodiment, four cylinders # 1, # 2, # 3, and # 4), and a cylinder block 2 of the engine 1 has cylinder bores corresponding to the number of cylinders. 3 are formed. Each cylinder bore 3 is located above the cylinder block 2.
The cylinder head 4 is assembled so as to close the cylinder head. A piston 5 is provided in each cylinder bore 3 so as to be vertically movable, and the piston 5 is connected to a crankshaft (not shown) via a connecting rod 6. Further, inside the cylinder bore 3, a space surrounded by the piston 5 and the cylinder head 4 is a combustion chamber 7.

The cylinder head 4 is provided with an ignition plug 8 corresponding to each of the combustion chambers 7. Also,
The cylinder head 4 is provided with an intake port 9 and an exhaust port 10 communicating with each combustion chamber 7, respectively. An intake passage 11 and an exhaust passage 12 are connected to each of the ports 9, 10, respectively. Furthermore, the intake port 9
An opening / closing intake valve 13 and an exhaust valve 14 are provided at each open end of the exhaust port 10 communicating with the combustion chamber 7. The intake valve 13 and the exhaust valve 14 are opened and closed in conjunction with the rotation of a crankshaft by a valve train including a camshaft (not shown). The opening and closing timings of these valves 13 and 14 are opened and closed in synchronization with the rotation of the crankshaft.

An air cleaner 1 is provided on the inlet side of the intake passage 11.
5 are provided. In the middle of the intake passage 11,
A surge tank 16 for smoothing the pulsation of the air passing through the passage 11 is provided. Further, on the downstream side of the surge tank 16, in the vicinity of the intake port 9 for each cylinder, an injector 17 as a fuel injection means is provided. Fuel of a predetermined pressure is supplied to these injectors 17 from a fuel tank (not shown) by a fuel pump. On the other hand, on the outlet side of the exhaust passage 12, a catalytic converter 18 having a built-in three-way catalyst for purifying exhaust gas is provided.

The engine 1 has an air cleaner 15.
Is taken in through the intake passage 11 including the surge tank 16. Further, when fuel is injected from each injector 17 simultaneously with the introduction of the outside air, a mixture of the outside air and the fuel is taken into the combustion chamber 7 in synchronization with the opening of the intake valve 13 in the intake stroke. Further, when the air-fuel mixture taken into the combustion chamber 7 is ignited by the spark plug 8, the air-fuel mixture explodes and burns, so that the engine 1 can obtain a driving force. The exhaust gas after the explosion and combustion is guided to the exhaust passage 12 in synchronization with the opening of the exhaust valve 14 in the exhaust stroke, and is discharged from the exhaust passage 12 to the outside through the catalytic converter 18 and the like.

An upstream side of the surge tank 16 is provided with a throttle valve 19 which opens and closes in response to operation of an accelerator pedal (not shown). By opening and closing the throttle valve 19, the amount of outside air taken into the intake passage 11, that is, the intake air amount Q is adjusted.
In the vicinity of the throttle valve 19, a throttle sensor 31 for detecting the opening of the valve 19, that is, the throttle opening TA is provided. This throttle sensor 31 outputs a signal of the throttle opening degree TA. A fully closed switch 42 is provided adjacent to the throttle sensor 31. The fully closed switch 42 outputs an ON signal only when the throttle valve 19 is at the fully closed position. On the downstream side of the air cleaner 15, there is provided an air flow meter 32 for detecting an intake air amount Q to the intake passage 11. Air cleaner 1
Between the air flow meter 5 and the air flow meter 32, an intake air temperature sensor 33 for detecting the temperature of the air taken into the intake passage 11, that is, the intake air temperature THA is provided.

Further, an oxygen sensor 34 for detecting the oxygen concentration in the exhaust gas, that is, for detecting the exhaust air-fuel ratio in the exhaust gas passage, is provided in the exhaust passage 12. Further, the cylinder block 2 is provided with a water temperature sensor 35 for detecting the temperature of the cooling water of the engine 1, that is, the cooling water temperature THW.

The ignition signal distributed by the distributor 20 is applied to the ignition plug 8 for each cylinder. The distributor 20 distributes the high voltage output from the igniter 21 to each ignition plug 8 in synchronization with the rotation of the crankshaft, that is, the crank angle. The ignition timing of each ignition plug 8 is determined by the high voltage output timing from the igniter 21.

The distributor 20 has a built-in rotor (not shown) which is rotated in association with the rotation of the crankshaft. And the distributor 20
A rotation speed sensor 36 for detecting the rotation speed of the engine 1, that is, the engine rotation speed NE from the rotation of the rotor is provided. Similarly, the distributor 20 is provided with a cylinder discrimination sensor 37 that detects a crank angle reference signal GP of the engine 1 at a predetermined rate according to the rotation of the rotor. In this embodiment, the crankshaft makes two rotations for a series of strokes in the engine 1,
The rotation speed sensor 36 detects the crank angle at a rate of 30 ° CA per pulse. The cylinder discrimination sensor 37 is 1
The crank angle is detected at a rate of 360 ° (720 ° CA) per pulse.

Further, the vehicle is provided with an automatic transmission (not shown) which can be drivingly connected to the engine 1. The automatic transmission is provided with a vehicle speed sensor 38 for detecting the speed of the vehicle, that is, the vehicle speed SPD. . Similarly, the automatic transmission is provided with a shift position sensor 40 for detecting a shift position (D range, R range, N range, etc.) at that time.

In addition, a bypass passage 22 that bypasses the throttle valve 19 and connects the upstream side and the downstream side of the throttle valve 19 to each other is provided in the intake passage 11. In the middle of this bypass passage 22, a well-known linear solenoid type idle speed control valve (I
SCV) 23 is provided. And ISCV23
Is driven and controlled based on a predetermined control signal, so that the bypass passage 22 is opened and closed.
The ISCV 23 is operated to stabilize the idling of the engine 1 when the throttle valve 19 is fully closed. Therefore, when the engine 1 is idling, the amount of air flowing through the bypass passage 22 is adjusted by controlling the opening of the ISCV 23 and the valve opening time thereof, that is, by performing the ISC control. The air amount Q and, consequently, the engine speed NE are adjusted.

The engine 1 is provided with a starter 24 for applying a rotational force to the engine 1 by cranking at the time of starting. The starter 24 has a starter switch 39 for detecting its operation / non-operation.
Is provided. The starter switch 39 is turned on / off by the operation of an ignition switch (not shown). Since the starter 24 is operated while the ignition switch is being operated, the starter switch 39 outputs an “ON” starter signal. Is output.

Further, the brake pedal 25 is provided with a brake sensor 41. The brake sensor 41
Outputs an ON signal when the brake pedal 25 is depressed or the side brake is operated.

Each injector 17, igniter 21, and ISCV 23 are connected to an electronic control unit (hereinafter simply referred to as “EC
U ”) 51, and their drive timing is controlled by the operation of the ECU 51. The ECU 51 constitutes first fuel injection amount control means, scavenging determination means, and second fuel injection amount control means. The ECU 51 includes the above-described throttle sensor 31, air flow meter 32, intake air temperature sensor 33, Oxygen sensor 34,
Water temperature sensor 35, rotation speed sensor 36, cylinder discrimination sensor 3
7, vehicle speed sensor 38, starter switch 39, shift position sensor 40, brake sensor 41 and fully closed switch 4
2 (these may constitute state detection means) are connected to each other. The ECU 51 controls the ignition timing, the fuel injection amount, the ISC control, and the like of the engine 1 based on output signals from the sensors 31 to 42 and the like.
Each injector 17, igniter 21 and ISCV23
Is suitably controlled.

Next, the electrical configuration of the ECU 51 will be described with reference to the block diagram of FIG. The ECU 51 includes a central processing unit (CPU) 52, a read-only memory (ROM) 53 in which a predetermined control program and the like are stored in advance, and a random access memory (RA) for temporarily storing the calculation results of the CPU 52 and the like.
M) 54, Backup R for storing stored data
An AM 55, a timer counter 56, and the like, and a logical operation circuit formed by connecting these components to an external input circuit 57, an external output circuit 58, and the like via a bus 59.
In the present embodiment, the ROM 53 stores in advance control programs such as an “injection amount calculation routine” to be described later, a map of ignition timing, injection timing control, and the like. The timer counter 56 outputs an interrupt signal every predetermined time and simultaneously performs a plurality of counting operations.

The external input circuit 57 includes the above-described throttle sensor 31, air flow meter 32, and intake air temperature sensor 3.
3, oxygen sensor 34, water temperature sensor 35, rotation speed sensor 3
6. Cylinder discrimination sensor 37, vehicle speed sensor 38, starter switch 39, shift position sensor 40, brake sensor 4
1 and a fully closed switch 42 are connected to each other.
Further, the injector 17, the igniter 21, the ISCV 23, and the like are connected to the external output circuit 58.

Then, the CPU 52 reads, as input values, signals from the sensors 31 to 42 and the like input via the external input circuit 57. Further, the CPU 51 suitably controls the driving of the injectors 17, the igniter 21, the ISCV 23 and the like based on the read input values.

Next, control contents in the fuel injection control device configured as described above will be described with reference to flowcharts shown in FIGS. 3 to 8 and a timing chart of FIG.

That is, the flowchart shown in FIG.
The "cranking continuation time calculation routine" executed by the ECU 51 is executed by interruption every predetermined time (in this embodiment, "every second"). The ECU 51 repeatedly reads signals from the various sensors 31 to 42 at the timing of an interrupt signal output from the timer counter 56 at predetermined intervals.

When the processing shifts to this routine, the ECU
First, at step 101, the control unit 51 determines whether or not the starter signal is "ON" based on the output from the starter switch 39. That is, it is determined whether or not cranking is being performed. If the starter signal is “ON”, the cranking duration TCRNK is incremented by “1” in step 102, and the process proceeds to the next step 103. On the other hand, when the starter signal is “off”, it is determined that cranking has not been executed, and the cranking duration TCRN is determined.
The process proceeds to step 103 while keeping K at “0”.

In step 103, it is determined whether or not the engine 1 has started. When determining whether or not the engine has started, whether or not the engine speed NE is equal to or higher than a predetermined speed is considered. Then, when the engine 1 is started (including the case where it is started), the cranking duration TCRNK is cleared to "0", and the subsequent processing is temporarily ended. On the other hand, if the engine 1 has not been started yet, the subsequent processing is temporarily terminated without performing any processing.

As described above, in the "cranking duration calculation routine", the cranking duration TCRNK continues to be incremented when cranking is being executed and the engine 1 is not started. It will be.

Next, the calculation process of the crank position will be described. That is, the flowchart shown in FIG.
"Crank position calculation routine" executed by U51
And is executed by interruption every predetermined crank angle (in this embodiment, “every 30 ° CA”).

When the processing shifts to this routine, the ECU
First, at step 201, it is determined whether or not the crank angle reference signal GP has been input from the cylinder determination sensor 37. If the crank angle reference signal GP has not been input, in step 202, the crank position counter CCRNK is incremented by "1".

In the following step 203, it is determined whether or not the current crank position counter CCRNK is "24" or more. Note that the numerical value “24” corresponds to “720 ° CA”.
If the crank position counter CCRNK is not equal to or greater than “24”, the subsequent processing is temporarily terminated. Also, the crank position counter CCRNK is "24".
If so, the process proceeds to step 204. In step 204, it is determined that a series of strokes in the engine 1 has been completed and the crank position counter CCRN is determined.
K is cleared to "0", and the subsequent processing is temporarily terminated.

On the other hand, even if the crank angle reference signal GP is inputted in step 201,
In step 04, the crank position counter CCRNK is cleared to "0", and the subsequent processing is temporarily terminated.

As described above, in the "crank position calculation routine", the crank position counter CCRNK is executed every time the routine is executed by interruption every predetermined crank angle (in this embodiment, "30 ° CA"). Is incremented and set within the range of “0” to “23”.

Next, the calculation processing of the injection cylinder will be described. That is, the flowchart shown in FIG.
1 shows an “injection cylinder calculation routine” executed by the routine 1, which is also executed by interruption every predetermined crank angle (in this embodiment, “every 30 ° CA”).

When the processing shifts to this routine, the ECU
51, first, in step 301, it is determined whether or not the crank position counter CCRNK set in the "crank position calculation routine" is "0". Then, the crank position counter CCRNK is set to "0".
In step 302, in order to set the injection cylinder to the cylinder # 1, the injection cylinder number CYLND is set to "1" in step 302.
And the subsequent processing is temporarily terminated.

If the value of the crank position counter CCRNK is not "0", the routine proceeds to step 303. In step 303, the crank position counter CCR
It is determined whether or not NK is “6”. When the crank position counter CCRNK is "6", the injection cylinder number CYLND is set to "3" in step 304 to set the injection cylinder to the cylinder # 3, and the subsequent processing is temporarily terminated.

Further, a crank position counter CCRNK
If is not “6”, the process proceeds to step 305.
In step 305, the crank position counter CC
It is determined whether or not RNK is “12”. When the crank position counter CCRNK is "12",
In order to set the injection cylinder to cylinder # 2, in step 306, the injection cylinder number CYLND is set to "2", and the subsequent processing is temporarily terminated.

In addition, a crank position counter CCRNK
If is not “12”, the process proceeds to step 307. In step 307, it is determined whether or not the crank position counter CCRNK is "18". If the crank position counter CCRNK is "18", step 3 is performed to set the injection cylinder to cylinder # 4.
At 08, the injection cylinder number CYLND is set to "4", and the subsequent processing is once ended.

On the other hand, if the crank position counter CCRNK is not "18", the flow shifts to step 309.
In step 309, it is determined that there is no corresponding injection cylinder at present, not the injection timing, and the injection cylinder number CYLND is set to “0”, and the subsequent processing is temporarily terminated.

As described above, in the "injection cylinder calculation routine", it is determined whether or not the present timing is at the injection timing based on the crank position counter CCRNK, and if it is at the injection timing, the injection cylinder is set. Injection cylinder number CYLND is set as needed.

Next, the process for determining the presence or absence of scavenging will be described. That is, the flowchart shown in FIG.
This shows a “scavenging flag setting routine” executed by 51, which is also executed by interruption every predetermined crank angle (in this embodiment, “30 ° CA”).

When the processing shifts to this routine, the ECU
51, first, in step 401, it is determined whether or not the cranking duration TCRNK set in the "cranking duration calculation routine" is equal to or longer than a predetermined time T1. And
If the cranking continuation time TCRNK is not equal to or longer than the predetermined time T1, it is determined that scavenging is not necessary yet, and the process proceeds to step 404.

In step 404, the scavenging flag F
SK is set to “0”, and the subsequent processing is temporarily ended.
On the other hand, when the cranking continuation time TCRNK is equal to or longer than the predetermined time T1, it is determined that the engine 1 has not been started even though the cranking has been performed for a relatively long time, Move to step 402.

In step 402, the injection cylinder number CY set in the above-described "injection cylinder calculation routine".
It is determined whether LND is “1” or “2”. That is, it is determined whether the cylinder at the current injection timing is the cylinder # 1 or # 2. And the injection cylinder number C
When YLND is either “1” or “2”, it is determined that scavenging is to be performed, and the process proceeds to step 403.

In step 403, the scavenging flag F
SK is set to “1”, and the subsequent processing is temporarily ended.
If the injection cylinder number CYLND is neither "1" nor "2", the flow proceeds to step 404, where the scavenging flag FSK is set to "0", and the subsequent processing is temporarily terminated.

As described above, in the "scavenging flag setting routine", the scavenging flag is set only when the cranking continuation time TCRNK is equal to or longer than the predetermined time T1 and the injection cylinder number CYLND is "1" or "2". FSK is set to "1", otherwise the scavenging flag FS
K is set to “0”.

Next, the calculation processing of the fuel injection amount will be described. That is, the flowchart shown in FIG.
This shows an “injection amount calculation routine” executed by 51 and is also executed by interruption every predetermined crank angle (in this embodiment, “30 ° CA”).

When the processing shifts to this routine, the ECU
51, first, at step 501, the scavenging flag F set in the "scavenging flag setting routine".
It is determined whether or not SK is “1”. If the scavenging flag FSK is not “1”, it is determined that scavenging is not necessary, and the reference start-time injection amount α (which may be a predetermined value or is calculated in a separate routine. ) Is set as the final startup injection amount TINJ, and the subsequent processing is temporarily terminated.

On the other hand, if the scavenging flag FSK is "1", it is determined that scavenging must be performed, and a predetermined coefficient K (0 ≦ K <1.0) is determined for the reference starting injection amount α. Is set as the final startup injection amount TINJ, and the subsequent processing is temporarily terminated.

As described above, in the “injection amount calculation routine”, when the scavenging flag FSK is “0”, the reference starting injection amount α is set as the starting injection amount TINJ, and the scavenging flag FSK is set to “1”. In this case, a smaller value (K · α) is set as the starting injection amount TINJ.

Next, the fuel injection execution process will be described. That is, the flowchart shown in FIG.
1 shows an “injection execution routine” executed by the routine 1 and is also executed by interruption every predetermined crank angle (in this embodiment, “every 30 ° CA”).

When the processing shifts to this routine, the ECU
51, first, in step 601, it is determined whether or not the current injection cylinder number CYLND is "0". When the current injection cylinder number CYLND is “0”, it is determined that the current injection timing is not at the injection timing, and the subsequent processing is temporarily terminated without executing the injection.

On the other hand, the current injection cylinder number CYLN
If D is not “0”, the current injection cylinder number CYL
Assuming that the ND is any one of “1”, “2”, “3”, and “4”, and the injection needs to be executed, step 60
Move to 2. In step 602, fuel injection is executed based on the current injection cylinder number CYLND and the start-time injection amount TINJ set in the above-described "injection amount calculation routine", and the subsequent processing is temporarily terminated.

As described above, in the "injection execution routine", when the current time is the injection timing, the fuel injection is executed. In this injection, the normal start-time injection amount TINJ (= α) is executed for the cylinders # 3 and # 4 regardless of the scavenging flag FSK.
When the scavenging flag FSK is set to “0” for the cylinders # 1 and # 2, injection is performed by the normal start-time injection amount TINJ (= α), and the scavenging flag FS
Only when K is set to “1”, the injection is performed by a smaller startup injection amount TINJ (= K · α).

Next, the operation and effect of this embodiment will be described. According to the present embodiment, when the cranking duration TCRNK is equal to or longer than the predetermined time T1, the engine 1 is turned on even though the cranking has been performed for a relatively long time. Is determined not to have been started, and the scavenging flag FSK is set to "1" only when the injection cylinder number CYLND is "1" or "2".

At the time of fuel injection, as shown in FIG. 9, regardless of the scavenging flag FSK, cylinder ♯
For 3, 4 the normal injection amount TINJ (=
Injection is performed only for α). For the cylinders # 1 and # 2, the scavenging flag FSK is set to "1", so that the starting injection amount TINJ (= K.
Injection is performed only for α).

For this reason, when it is determined that scavenging is necessary, the degree of scavenging request varies depending on various conditions, but when the degree of scavenging request is large, the injection amount is reduced. When combustion occurs in cylinders # 1 and # 2 and the degree of scavenging demand is small, combustion may occur in cylinders # 3 and # 4 whose injection amount has not been reduced. If combustion occurs in any one of the cylinders (combustion chamber 7), the combustion becomes complete after that, and the engine 1
Starts. Therefore, if the engine 1 cannot be started even if the cranking is continued for the predetermined time T1, by executing this control, the scavenging state (air-fuel ratio) is changed for any of the cylinders # 1 to # 4. Since it can be appropriate or close to it, the startability can be further improved.

It should be noted that the present invention is not limited to the above-described embodiment, and may be carried out as follows by appropriately changing a part of the configuration without departing from the spirit of the invention. (1) In the above embodiment, it is determined that the engine 1 has not been started even though cranking has been performed for a relatively long time, and the injection cylinder number CYLN has been used.
Only when D is "1" or "2", the scavenging flag FSK is set to "1". In that case, the cylinder #
Although the fuel injection amount is reduced for 1 and # 2, the fuel may be completely cut off (the start-up injection amount TINJ is set to zero).

(2) In the above embodiment, the cylinders # 1, # 1
Although the injection amount was reduced for 2, it is only necessary that a part of the injection amount be reduced. For example, for only cylinder # 1,
Alternatively, the cylinders # 1 to # 3 may be reduced.

The target of the weight reduction may be changed according to the state of the engine 1 at that time. In this case, scavenging in accordance with the state of the engine 1 at that time, and furthermore, scavenging in accordance with the degree of scavenging demand is performed more appropriately.

Further, in the above-described embodiment, the present invention is embodied in the case of four cylinders. However, any engine having a plurality of cylinders may be used. For example, the present invention may be embodied in the case of six cylinders or eight cylinders.

(3) Although not described in the above embodiment, the amount of fuel to be reduced may be adjusted according to the state of the engine 1 at that time. It is also possible to change the degree of weight reduction for each cylinder. In this case,
The degree of scavenging can be made variable according to the state of the engine 1 at that time, and thus the degree of scavenging demand,
It is possible to further improve the startability.

[0074]

As described above in detail, the fuel injection control device for an internal combustion engine according to the present invention has an excellent effect that the startability can be dramatically improved.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a fuel injection control device for an engine.

FIG. 2 is a block diagram showing an electrical configuration of an ECU.

FIG. 3 is a flowchart illustrating a “cranking duration calculation routine” executed by an ECU according to one embodiment;

FIG. 4 is a flowchart showing a “crank position calculation routine” executed by the ECU.

FIG. 5 is a flowchart showing an “injection cylinder calculation routine” executed by the ECU.

FIG. 6 is a flowchart showing a “scavenging flag setting routine” executed by the ECU.

FIG. 7 is a flowchart showing an “injection amount calculation routine” executed by the ECU.

FIG. 8 shows an “injection execution routine” executed by the ECU.
It is a flowchart which shows.

FIG. 9 is a timing chart showing a behavior of a fuel injection amount for each cylinder with respect to time.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Engine as an internal combustion engine, 7 ... Combustion chamber, 9 ... Intake port, 11 ... Intake passage, 17 ... Injector as fuel injection means, 31 ... Throttle sensor, 32 ... Air flow meter, 33 ... Intake temperature sensor, 34 ... Oxygen sensor 3
4, 35: water temperature sensor, 36: rotation speed sensor, 37: cylinder discrimination sensor, 38: vehicle speed sensor, 39: starter switch, 40: shift position sensor, 41: brake sensor, 42: fully closed switch, 51: ECU.

Claims (4)

[Claims] 1. A fuel injection means for supplying fuel to each combustion chamber of an internal combustion engine having a plurality of combustion chambers, and fuel injected from the fuel injection means when cranking of the internal combustion engine is performed. First fuel injection amount control means for determining the amount of fuel to be injected and controlling the injection from the fuel injection means based on the determined amount of fuel; and A scavenging determining means for determining whether scavenging of the intake passage and the combustion chamber on the downstream side of the fuel injection means is necessary, and if the scavenging determining means determines that scavenging is necessary, A second method in which the amount of fuel injected from a part of the plurality of fuel injection means is reduced from the amount of fuel determined by the first fuel injection amount control means or is zero.
A fuel injection control device for an internal combustion engine, comprising: a fuel injection amount control means. 2. The scavenging determination means determines that scavenging is necessary when the internal combustion engine does not become a complete explosion state even after a predetermined time has elapsed since the start of cranking of the internal combustion engine. The fuel injection control device for an internal combustion engine according to claim 1, wherein: 3. The fuel injection control device for an internal combustion engine according to claim 1, further comprising: a state detection unit configured to detect a state of the internal combustion engine; A fuel injection control device for an internal combustion engine, further comprising a fuel injection amount control means for adjusting a fuel amount reduced by the fuel injection amount control means. 4. The fuel injection control device for an internal combustion engine according to claim 1, further comprising: a state detection unit that detects a state of the internal combustion engine; and an injection amount based on a detection result of the state detection unit. A fuel injection control device for an internal combustion engine, comprising: a variable fuel injection means for varying a fuel injection means to be reduced.