JPH06185387A - Fuel injection controller for internal combustion engine - Google Patents

Abstract

PURPOSE:To provide a fuel injection controller for an internal combustion engine capable of performing suitable fuel supply to cylinders without deterioration of startability. CONSTITUTION:A crank angle sensor 25 outputs a crank angle signal at each predetermined crank angle according to rotation of a crankshaft or camshaft of a 4-cylinder spark ignition type gasoline engine 1. A cylinder judging sensor 24 outputs a cylinder judging signal in each predetermined position of a specific cylinder according to the rotation of the crankshaft or camshaft of the engine 1. An ECU 27 performs asynchronous injection in an injector 6 with respect to all cylinders immediately after the start of the engine 1. Furthermore, the ECU 27 carries out synchronous injection at the time of the start from the injector 6 with respect to the cylinder to be judged that completion of suction into a combustion chamber 12 of asynchronous injection fuel at the time of starting on the basis of inverse calculation by using a crank angle signal output from the crank angle sensor 25 when a cylinder judging signal output from the cylinder judging sensor 24 is detected.

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 at the time of starting.

[0002]

2. Description of the Related Art Conventionally, in Japanese Patent Publication No. 63-14174, at the time of starting, the first crank angle signal is used to simultaneously perform synchronous injection for all cylinders and then stop injection at 720.degree. To prevent. However, when two crank angle signals of 720 ° C and 180 ° C are used, synchronous injection of all cylinders is started at the first 180 ° C signal detection, and thereafter injection between 720 ° A is stopped. It is a thing.

[0003]

However, the first 18
The injection does not start until the 0 ° C A signal can be detected. Therefore, there remains a problem that the startability is deteriorated by a maximum of 180 ° C.

Therefore, an object of the present invention is to provide a fuel injection control device for an internal combustion engine which can optimize the fuel supply to each cylinder without deteriorating the startability.

[0005]

SUMMARY OF THE INVENTION The present invention is directed to a crank angle sensor for generating a crank angle signal for each predetermined crank angle associated with the rotation of a crankshaft or a camshaft of a multi-cylinder internal combustion engine, and a crank of the multi-cylinder internal combustion engine. A cylinder discrimination sensor that generates a cylinder discrimination signal for each specific position of a specific cylinder due to the rotation of a shaft or a camshaft, an injector that injects fuel into the intake system of a multi-cylinder internal combustion engine, and immediately at the start of starting the multi-cylinder internal combustion engine. Asynchronous injection means at startup for performing asynchronous injection from all injectors to all cylinders, and injection of the asynchronous injection fuel at startup by back calculation using the crank angle signal of the crank angle sensor at the time of detecting the cylinder discrimination signal of the cylinder discrimination sensor. The start-time asynchronous injection timing calculation means for obtaining start and end timings and the start-time asynchronous injection timing calculation means SUMMARY OF THE INVENTION A fuel injection control device for an internal combustion engine, comprising: a fuel injection control unit that causes the injector to perform synchronous injection at the time of startup to a cylinder that has determined that intake of asynchronous injection fuel into a combustion chamber has ended. It is what

[0006]

The starting asynchronous injection means performs the asynchronous injection from the injectors to all the cylinders immediately after starting the start of the multi-cylinder internal combustion engine. Further, the start-time asynchronous injection timing calculation means obtains the injection start and end timings of the start-time asynchronous injection fuel by back calculation using the crank angle signal of the crank angle sensor when the cylinder discrimination signal of the cylinder discrimination sensor is detected.
Further, the fuel injection control means causes the injector to perform the synchronous injection at the time of startup to the cylinder for which it has been determined by the startup asynchronous injection timing calculation means that the intake of the asynchronous injection fuel at the startup has been completed.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows an overall schematic diagram of a fuel injection control device for an internal combustion engine. The device is mounted on a vehicle.

An intake pipe 2 and an exhaust pipe 3 are connected to the 4-cylinder spark ignition gasoline engine 1. An air cleaner 4 is provided at the most upstream part of the intake air cleaner 2.
The intake air is drawn into the intake pipe 2.
A surge tank 5 is provided in the middle of the intake pipe 2.
Intake pipe (intake port) 2 for each cylinder in engine 1
An injector (fuel injection valve) 6 is arranged in each of the above. Further, the fuel in the fuel tank 7 is sucked up by the fuel pump 8 and supplied to the pressure regulator 10 through the fuel filter 9, and the pressure regulator 1
The pressure is regulated at 0 and the fuel is returned to the fuel tank 7 again. The fuel whose pressure has been adjusted to this constant pressure is supplied to the injector 6. Then, the injector 6 is opened by the power supply from the battery 15. As a result, the fuel is injected and mixed with the intake air to form an air-fuel mixture, which is supplied to the combustion chamber 12 of each cylinder of the engine 1 via the intake valve 11.

A spark plug 13 is arranged in each combustion chamber 12 of each cylinder of the engine 1. Then, the igniter 14 generates a high voltage from the voltage of the battery 15, and the distributor 16 distributes the high voltage to the spark plug 13 of each cylinder.

Further, a bypass passage 18 is formed so as to bypass a throttle valve 17 provided in the middle of the intake pipe 2, and an idle speed control valve 19 is arranged in the bypass passage 18. When the engine is idle, the engine speed is adjusted by adjusting the opening of the idle speed control valve 19.

An intake air temperature sensor 20 is provided at the most upstream portion of the intake pipe 2.
Is provided, and the intake air temperature can be detected by the sensor 20. Also, the throttle valve 17 of the intake pipe 2
A throttle opening sensor 21 is provided in the vicinity of the arrangement position of, and the opening of the throttle valve 17 can be detected by the throttle opening sensor 21. further,
The intake pipe internal pressure sensor 22 can detect the intake pipe internal pressure in the surge tank 5.

The engine 1 is provided with a water temperature sensor 23 for detecting the temperature of engine cooling water. A cylinder discrimination sensor 24 and a crank angle sensor 25 are arranged in the distributor 16. The crank angle sensor 25 generates a crank angle signal for each predetermined crank angle associated with the rotation of the crank shaft or the cam shaft of the engine 1.
The cylinder discrimination sensor 24 also generates a cylinder discrimination signal for each specific position of a specific cylinder associated with rotation of the crankshaft or camshaft of the engine 1. More specifically, as shown in FIG. 7, the cylinder discrimination sensor 24 outputs two types of cylinder discrimination signals and the crank angle sensor 25 outputs a crank angle signal. Here, the cylinder discrimination signal is a signal for knowing where the engine is now, and in the embodiment of FIG. 7, the compression TDC of the first cylinder and the compression TDC of the fourth cylinder.
Is a signal generated at.

The cylinder discrimination signal is a signal for detecting a specific position of the specific cylinder (for example, the compression TDC of the first cylinder) at least once in the crankshaft 720 ° C., and the crank angle signal is the crank shaft 180 ° A. It is a signal that is generated a plurality of times and that is generated at a cycle of at least 30 ° C. or less.

In FIG. 1, the exhaust pipe 3 of the engine 1 is provided with an oxygen concentration sensor 26.
6, the oxygen concentration in the exhaust gas of the engine 1 can be detected.

An electronic control unit (hereinafter referred to as ECU) 27 as fuel injection control means is mainly composed of a microcomputer. A signal associated with the drive of the starter motor from the starter switch 28 is input to the ECU 27. Further, the ECU 27 includes an intake air temperature sensor 20, a throttle opening sensor 21, an intake pipe pressure sensor 22, a water temperature sensor 23, a cylinder discrimination sensor 24, and a crank angle sensor 2.
5 is connected. Then, the ECU 27 inputs signals from these sensors to input intake air temperature and throttle valve 1
The opening degree of 7, the intake pipe pressure, the engine cooling water temperature, the oxygen concentration of the exhaust gas, etc. are detected.

A battery 15 is connected to the ECU 27, and the ECU 27 detects the voltage of the battery 15. Further, the engine 1 is a starter motor (not shown).
Receives electric power from the battery 15 and drives to start (crank) the engine 1.

Next, the operation of the fuel injection control device for the internal combustion engine thus configured will be described. 2 to 6 show the ECU
27 shows a process (flow chart) executed by 27. Less than,
The processing of the ECU 27 will be described with reference to FIG. 7.

In FIG. 7, a indicates a starter signal,
b and c indicate a cylinder discrimination signal which is alternately generated every 360 ° C. A, d is a crank angle signal which is generated every predetermined angle (for example, every 30 ° C. A), and e is the injection of the first cylinder, f,
g and h indicate the injections of the third, fourth and second cylinders, respectively.

In FIG. 2, when the starter switch 28 is turned on and the starter motor is driven, the routine process is started. Then, the ECU 27 executes step 10
At 1, it is determined whether or not it is the asynchronous injection timing at startup. In the present embodiment, this timing indicates whether or not 50 msec has elapsed after the starter switch 28 was turned on. The ECU 27 determines that the asynchronous injection timing at start (timing of t1 in FIG. 7) is step 102.
The injector 6 executes the asynchronous injection for all cylinders at the same time (corresponding to the asynchronous injection means at startup).

FIG. 3 shows the calculation process of the asynchronous injection pulse at the time of starting in step 102 of FIG. The same processing is started by turning on the starter switch 28 (starting drive of the starter motor). ECU2
Step 7 detects the water temperature THW in Step 201, and Step 2
02: Asynchronous injection pulse TAS at startup according to the water temperature THW
Calculate Y. Further, the ECU 27 detects the battery voltage BAT in step 203, and calculates the invalid injection pulse TV according to the battery voltage BAT in step 204.
Then, in step 205, the ECU 27 adds the invalid injection pulse TV to the starting asynchronous injection pulse TASY to calculate the final injection pulse TAU (= TASY + TV).

In FIG. 7, this final injection pulse TAU
Asynchronous injection for all cylinders is performed only (t1 to t in FIG. 7).
2 timing). The ECU 27 also executes the process shown in FIG. 4 for each predetermined crank.

In step 301, the ECU 27 determines whether or not it is the first synchronous injection after the start of the engine. When the cylinder discrimination signal is detected (timing t3 in FIG. 7), the ECU 27 confirms in step 303 that the asynchronous injection at startup is completed, and then executes step 3
Move to 04. In step 304 (corresponding to the asynchronous injection timing calculation means at the time of starting), the ECU 27 performs backward calculation using the crank angle signal from the cylinder discrimination time point (timing of t3) as shown in FIG. Calculate TAF. Then E
In step 305, the CU 27 determines in which stroke in each cylinder the asynchronous injection was performed based on the asynchronous injection start timing TAS and the asynchronous injection end timing TAF.

That is, in FIG. 7, the first cylinder has an intake stroke, the third cylinder has an exhaust stroke, the fourth cylinder has an expansion stroke, and the second cylinder has a compression stroke. Subsequently, in step 306 of FIG. 4, it is determined whether the injection timing has come, and when the injection timing comes, step 3
The synchronous injection is executed at 07 (t4 to t5, t6 to FIG. 7).
t7, t8 to t9).

In FIG. 7, the injection timing is 100 ° CA after the cylinder discrimination in the first and third cylinders (Te = Tf = 100 ° CA), and 280 ° in the fourth cylinder.
When CA has elapsed (Tg = 280 ° CA), 46 in the second cylinder
It is assumed that 0 ° CA has elapsed (Th = 460 ° CA).

At this time, in the case of the first cylinder, since the asynchronous injection fuel has already been sucked, the injection is started after Te has elapsed after the cylinder discrimination signal is detected. Te is the time for avoiding driving the injector 6 at TDC. That is, in TDC, the rotational resistance of the engine 1 is large and the load of the battery 15 is large. This prevents the battery voltage from decreasing during cranking by the starter motor, and prevents the injector 6 from falling below the minimum operating voltage. In the case of the fourth cylinder, the asynchronous injection fuel is sucked in after the first cylinder discrimination signal is detected. Therefore, the first synchronous injection is executed after Tg after the intake stroke.

Further, the synchronous injection at the time of starting must be injected at the earliest possible timing with respect to the intake stroke. Because you can get enough fuel evaporation time,
This is because it can be started with less fuel.

In this embodiment, the synchronous injection is an independent injection, but it may be a two-group injection. Further, in FIG. 7, in order to increase the evaporation time of the synchronous injection fuel of the third cylinder,
After the cylinder discrimination (after Tf), the injection is performed at an early timing, and as a result, the injection is performed at the same timing as the synchronous injection of the first cylinder. Therefore, it suffices to perform the injection in each cylinder at a timing that allows a long evaporation time, and it is not necessary to make the injection timings of the first and third cylinders at the same time.

On the other hand, if it is not the first synchronous injection after the start of starting in step 301 of FIG. 4, that is, 2 after the start of starting.
If it is the synchronous injection after the first time, it is determined in step 308 whether the injection timing has come, and if it is the injection timing, the synchronous injection is executed in step 309.

5 and 6, step 30 in FIG.
7 shows the calculation processing of the synchronous injection pulse in No. 7, 309.
The routine process is started every predetermined crank. In FIG. 5, the ECU 27 determines in step 401 whether or not the current engine speed Ne is smaller than 400 rpm, and N
If e <400 rpm, the process proceeds to step 402. Then, the ECU 27 determines in step 402 whether or not the previous engine speed Ne is 400 rpm or more, and 40
If it is less than 0 rpm, move to step 404, 400r
If it is pm or more, it is determined in step 403 whether or not the current engine speed Ne is 200 rpm or less. The ECU 27 detects the water temperature THW in step 404 after the processing of step 402 or if the current engine speed Ne is 200 rpm or less in step 403 (when the engine is started), and in step 405, injects at the time of startup according to the water temperature THW. Calculate the pulse TSTA. Then, in step 406, the ECU 27 sets the starting injection pulse TSTA to the effective injection pulse T
AUE

Further, the ECU 27 detects the battery voltage BAT in step 407, and calculates the invalid injection pulse TV in accordance with the battery voltage BAT in step 408. Then, the ECU 27 determines in step 409 that the effective injection pulse T
Final injection pulse T by adding invalid injection pulse TV to AUE
Calculate AU (= TAUE + TV).

On the other hand, the ECU 27 determines in step 401 that the current engine speed Ne is 400 rpm or more, or in step 403 that the current engine speed Ne is 200 rp.
If m or more (after engine start), step 4 in FIG.
Go to 10.

The ECU 27 detects the engine speed Ne in step 410, and detects the intake pressure Pm in step 411. Then, the ECU 27 calculates the intake pressure change amount ΔPm in step 412, and detects the intake temperature THA in step 413. Further, the ECU 27 detects the water temperature THW in step 414, and in step 415, the throttle opening TA
To detect. Subsequently, the ECU 27 detects the oxygen concentration in the exhaust gas in step 416, and calculates the basic injection pulse Tp in step 417 according to the engine speed Ne and the intake pressure Pm. Then, the ECU 27 determines in step 418 the water temperature T
The water temperature correction coefficient FWL is calculated according to HW, and step 41
At 9, the post-start correction coefficient FASE is calculated according to the water temperature THW and the elapsed time after the start. Further, the ECU 27 executes step 4
In step 20, the intake air temperature correction coefficient FTHA is calculated according to the intake air temperature THA, and in step 421, the high load correction coefficient FOTP is calculated according to the throttle opening TA, the engine speed Ne, and the intake pressure Pm.
To calculate.

Next, in step 422, the ECU 27 determines the air-fuel ratio feedback correction coefficient F according to the oxygen concentration in the exhaust gas.
A / F is calculated, and in step 423, the acceleration correction pulse TACC is calculated according to the intake pressure change amount ΔPm. And EC
U27 calculates the effective injection pulse TAUE using the following equation in step 424.

TAUE = Tp.FWL.FTHA. (FASE +
After calculating the effective injection pulse TAUE in step 424, the ECU 27 proceeds to step 407 in FIG. Then, as described above, the ECU 27 calculates the invalid injection pulse TV according to the battery voltage BAT in steps 407 and 408, and adds the invalid injection pulse TV to the effective injection pulse TAUE in step 409 to add the final injection pulse TAU (= TAUE + TV) is calculated.

As described above, in the present embodiment, the ECU 27 (start-up asynchronous injection means, start-up asynchronous injection timing calculation means, fuel injection control means) causes the injector 6 to perform asynchronous injection to all cylinders immediately when the engine 1 starts to start. A cylinder that has been determined to have completed the intake of the asynchronous injection fuel at startup into the combustion chamber 12 by back calculation using the crank angle signal of the crank angle sensor 25 when the cylinder determination signal of the cylinder determination sensor 24 is detected thereafter. The injector 6 is caused to perform synchronous injection at the time of starting. Therefore, all cylinders asynchronous injection is performed at the time of start-up, and fuel is sucked into the engine at an early timing to improve startability, while determining the timing of all cylinders asynchronous injection when the cylinder discrimination signal is detected and determining the synchronous injection timing of the first injection. As a result, excessive fuel supply can be prevented, rich misfire at start can be prevented, and emissions can be improved. In this way, the fuel supply to each cylinder can be optimized without deteriorating the startability.

Further, the first synchronous injection at the time of starting is executed at the earliest possible timing with respect to the intake stroke (at the latest, the timing at which the injection is finished before the intake valve starts to open), so that the vaporization time of the injected fuel is increased. Can be taken longer, which leads to improved atomization. Therefore, it is possible to ignite with a smaller amount of fuel, and it is possible to improve not only emission and startability but also smoldering resistance of the spark plug.

[0037]

As described above in detail, according to the present invention,
It has an excellent effect that the fuel supply to each cylinder can be optimized without deteriorating the startability.

[Brief description of drawings]

FIG. 1 is an overall schematic diagram of a fuel injection control device for an internal combustion engine of an embodiment.

FIG. 2 is a flowchart for explaining the operation.

FIG. 3 is a flowchart for explaining an operation.

FIG. 4 is a flowchart for explaining the operation.

FIG. 5 is a flowchart for explaining the operation.

FIG. 6 is a flowchart for explaining the operation.

FIG. 7 is a time chart for explaining the operation.

[Explanation of symbols]

1 Engine as Multi-Cylinder Internal Combustion Engine 6 Injector 24 Cylinder Discrimination Sensor 25 Crank Angle Sensor 27 Start-up Asynchronous Injection Means, Start-up Asynchronous Injection Timing Calculation Means, ECU as Fuel Injection Control Means

Claims (1)

[Claims] 1. A crank angle sensor for generating a crank angle signal for each predetermined crank angle accompanying rotation of a crankshaft or a camshaft of a multi-cylinder internal combustion engine, and a rotation of a crankshaft or a camshaft of the multi-cylinder internal combustion engine. A cylinder discrimination sensor that generates a cylinder discrimination signal for each specific position of a specific cylinder, an injector that injects fuel into the intake system of a multi-cylinder internal combustion engine, and an injector for all cylinders immediately after starting injection of the multi-cylinder internal combustion engine Asynchronous injection means at the time of starting for performing injection, and a start time for obtaining the injection start and end timings of the asynchronous injection fuel at the time of start by back calculation using the crank angle signal of the crank angle sensor at the time of detecting the cylinder discrimination signal of the cylinder discrimination sensor Asynchronous injection timing calculation means, and combustion of the asynchronous injection fuel at startup by the startup asynchronous injection timing calculation means The fuel injection control device for an internal combustion engine characterized by comprising a fuel injection control means for causing the synchronous injection at the start from the injector relative to the determined cylinder that inhalation to the inner ends.