JPH02267337A - Electronic fuel injection device - Google Patents

Abstract

PURPOSE:To inject always the appropriate quantity of fuel regardless of the length of valve-open time by controlling the drive of an injector using a valve- open time increasing rate map with the fuel temperature and the valve-open time of an injector as parameter. CONSTITUTION:When an engine is operated, a CPU 30 enumerates A/N (loaded condition) at an enumerating means 40 on the basis of the intake air flow information obtained by an air flow meter 6 and the engine speed information obtained by a crank angle sensor 24 and map-retreaves the basic valve-open time TB from this A/R at a setting means 41. Various correction coefficients corresponding to the operated state are then set at a setting means 42, and TB is multiplied by these correction coefficients so as to enumerate the injector valve open time TINJ. The valve-open time increasing rate map is retrieved by a setting means 43 on the basis of this TINJ and the fuel temperature detected by a fuel temperature sensor 17 so as to set a high temperature increased quantity correction coefficient KUP, as well as TINJ, 4 is multiplied by KUP to decide the valve open time, thus controlling the injector 12.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to an electronic fuel injection device 4? Specifically, the aim is to improve drivability and exhaust gas performance when restarting the engine after a hot soak.

<Prior art> Electronically controlled fuel injection device (ElecLoronic C
.

-trolled Injection Device
In an engine that employs ECI (hereinafter referred to as ECI), the amount of fuel injected is finely controlled in accordance with the intake flow rate, engine speed, throttle opening, and the like. Fuel injection control during normal operation is basically performed near the stoichiometric air-fuel ratio (or output air-fuel ratio), and during warm-up (fast idle) or restarting immediately after driving, the fuel injection control is performed depending on the cooling water temperature, fuel temperature, etc. The amount will be increased accordingly.

The fast idle increase is in response to the fact that when the engine, including the intake pipe, is cold, the vaporization of fuel (gasoline, etc.) becomes worse.As a form of control, the cooling water temperature is controlled by a water temperature sensor. This is to prevent the air-fuel mixture from becoming relatively lean (hereinafter referred to as "lean") by detecting and increasing the amount by a predetermined amount.

On the other hand, if the engine is suddenly stopped immediately after driving at high speed, the cooling system will stop working even though the engine is hot. As a result, the temperature in the engine room gradually rises, and a so-called vapor lock phenomenon occurs in which fuel vapor bubbles are generated inside the fuel pipes, injectors, and the like. When a vapor lock phenomenon occurs, even if the injector opens, the initially injected fuel contains bubbles, making it impossible to supply the planned amount of fuel. Therefore, in order to prevent the air-fuel mixture from becoming lean due to this, the restart amount is increased.

In restart fuel increase, the fuel temperature is first detected by the fuel temperature sensor, then the fuel increase coefficient corresponding to this fuel temperature is determined.
Thereafter, the injector is driven by multiplying the basic valve opening time of the injector by this increase coefficient.The increase coefficient is determined through experiments during idling operation, etc.

<Problems to be Solved by the Invention> By the way, in the above-mentioned restart fuel increase, the basic valve opening time is multiplied by a fuel increase coefficient corresponding to the fuel temperature, but as a result, the following problems occur. was.

The basic valve opening time during sudden acceleration or high-speed operation is naturally set to be longer than during idling operation. However, bubbles due to the vapor lock phenomenon are injected from the injector at the initial stage of injection. Therefore, if the valve opening time is long and the amount is increased by the same percentage, extra fuel will be injected into the combustion chamber, and if you start driving immediately after restarting, the air-fuel mixture will become overrich and drivability will deteriorate.
This results in an increase in harmful components (HC, Co, etc.) in the exhaust gas.

The present invention was made in view of the above situation, and an object of the present invention is to provide an electronic fuel injection device that can always inject an appropriate amount of fuel regardless of the length of the valve opening time.

<Means for Solving the Problem> Therefore, in order to solve this problem, the present invention provides an injector in which the fuel injection amount is determined by the valve opening time, a fuel temperature detection means for detecting the fuel temperature in the fuel pipe, and the following. , search the valve opening time increase rate map using the detection result of the fuel temperature detection means and the valve opening time of the injector as parameters, and search the valve opening time increase rate from this valve opening time increase rate map; The present invention proposes an electronic fuel injection device characterized by comprising: drive control means for controlling the drive of the injector by multiplying the valve opening time by a valve opening time increase rate.

Effect> Since the valve opening time increase rate map uses the fuel temperature and the injector valve opening time as parameters, for example, as the basic valve opening time increases, the valve opening time increase rate can be temporarily decreased, and restarting is possible. Overrich conditions at times are avoided.

<Example> Hereinafter, an example in which the present invention is applied to a gasoline engine with ECr will be specifically described based on the drawings.

FIG. 1 schematically shows the entire control system in this embodiment, and FIG. 2 shows the hardware configuration of an electronic control unit serving as a control center. Further, FIGS. 3 and 4 show a control flowchart and a control block diagram, respectively, and FIGS. 5 and 6 show a graph of the high temperature characteristics of the injector and a valve opening time increase rate map, respectively.

First, the hardware of the engine centralized control system in this embodiment will be briefly explained based on FIGS. 1 and 2.

In FIG. 1, E is a V-type six-cylinder automobile engine with ECI, and an intake pipe 3 to which an air cleaner box 2 is attached is connected to the upstream side of an intake manifold 1 via a surge chamber 4. An air cleaner 5 is housed in the air cleaner box 2, and in addition to a Karman vortex type air flow meter 6, an atmospheric pressure sensor 7 and an intake air temperature sensor 8 are provided therein. Further, a throttle valve 9 driven by an accelerator wire (not shown) is installed in the intake pipe 3, and a potentiometer-type throttle sensor 10 and an idle switch 11 are attached to the throttle valve 9.

On the other hand, the intake manifold 1 is equipped with injectors 12 corresponding to the number of cylinders. A delivery vibe 13, which is a fuel supply line, is connected to the injector 12, and the valve is opened by an electric signal (drive pulse), and the intake manifold 1
Fuel is injected inside. Incidentally, fuel from the fuel tank 14 is fed to the delivery vibe 13 under pressure by the fuel pump 15, but the pressure is set at a predetermined value by the fuel pressure regulator 16 (33% relative to the manifold negative pressure).
5 kg/d higher value). In the figure, 17 is a fuel temperature sensor that detects the fuel temperature within the delivery vibe 13.

A spark plug 18 is attached to a cylinder head E of an engine E, and an exhaust pipe 20 is connected to an exhaust manifold 19. The exhaust pipe 20 is equipped with a catalytic converter 21 inside the pipe, and a muffler 22 is connected to the rear end of the exhaust pipe 20. In the figure, 23 is a sensor for detecting the oxygen concentration in the exhaust gas. 24 and 25 are a crank angle sensor and a cylinder discrimination sensor attached to the camshaft 26.

Additionally, the engine E is also equipped with a cranking switch 27 for detecting the rotational state of the starter motor, a water temperature sensor 28 for detecting the cooling water temperature, and the like.

The sensors and controlled devices mentioned above are installed in the ECU (Electronic Control U) installed inside the vehicle.
nit) 29, and sends driving information to this ECU 29 in the form of electrical signals (hereinafter referred to as signals).
It is activated by the signal from 9. As shown in FIG. 2, the hardware configuration of the ECU 29 is mainly composed of a CPU 30.

Atmospheric pressure sensor 7, intake temperature sensor 8. Throttle sensor 1
0. Fuel temperature sensor 17,02 sensor 23. Water temperature sensor 28
Since the signals from etc. are analog signals, they are sent to the CP via the interface 31 and the A/D = 7 inverter 32.
Enter into U30. Also, the idle switch 11. Signals from the cranking switch 27, etc. are sent via the interface 31 to the air flow meter 6, crank angle sensor 24. The signals from the cylinder discrimination sensor 25 are directly
Input to PU30.

The CPU 30 also has a ROM (R
ead 0nly Memory) 3 B, RA
M (Random Access Memory)
In addition to 34, the memory contents are saved even if the ignition switch is turned off while the battery is connected.
AM (Battery Back Up Memory
) 35 is connected.

The CPU 30 performs calculations based on the various signals described above to determine the fuel injection amount, ignition timing, and the like. Then, the injector 12 is driven through the injector driver 36, and the spark plug 18 is driven through the ignition driver 37 and power transistor 38.

In the engine E, air sucked under negative pressure from the air cleaner 5 as the piston E2 descends is transferred to the air 70-meter 6.
The intake air amount, atmospheric pressure, and intake air temperature are detected by the atmospheric pressure sensor 7 and the intake air temperature sensor 8.Then, the flow rate of the air is adjusted by the throttle valve 9 in the intake pipe 3, and then the air enters the surge chamber. Intake manifold 1 via 4
At this point, gasoline is injected by the injector 12 to form an air-fuel mixture. The air-fuel mixture is attracted and compressed into the combustion chamber as the piston E2 moves up and down, and is ignited by the spark plug 18 near the top dead center.

When the explosion and expansion stroke are completed, the mixture becomes exhaust gas,
It flows into the exhaust pipe 20 via one exhaust manifold. Exhaust gas flowing into the exhaust pipe is purified by the catalytic converter 21 and released into the atmosphere from the muffler 22.

The operation of this embodiment will be explained below with reference to FIGS. 3 to 6. Note that the symbols (SL, S2°, . . . ) indicating the control step stages in the flowchart correspond to the symbols written at the end of the explanatory text.

When the ignition switch is turned on, the control shown in the flowchart of FIG. 3 is started.

After starting the control, the CPU 30 first collects various engine information such as intake air amount information from the air flow meter 6, engine speed information from the crank angle sensor 24, cooling water temperature information from the water temperature sensor 28, and fuel amount temperature information from the fuel temperature sensor 17. Load driving information. ...81 Next,
In the CPU 30, a starting mode determining means 39 determines whether the engine E is in the starting mode. This determination is made if the cranking switch 27 is in the on state and the engine speed is lower than a set value (for example, 400 rpm), then the starting mode is set, and otherwise, the normal operation mode is set.

...82 When the normal operation mode is determined, the CPU 30 next calculates Alx (load state) calculation means 40 based on the intake air amount information and engine rotation speed information, and from this Alx, the basic valve opening time setting means 41 searches for the basic valve opening time of the injector 12, that is, the basic valve opening time T8 from a map not shown. ...S3 Once the first basic valve opening time T8 is determined, the correction coefficient setting means 42 in the CPU 30 determines various correction coefficients according to the operating state of the engine. As a correction coefficient, warm air increase coefficient Kw engineering,
Intake air temperature coefficient KA, atmospheric pressure coefficient KAP + total P + coefficient KA
There are F, etc., and each has a cooling water temperature.

It is set through map searches and calculations based on intake temperature, atmospheric pressure, air-fuel ratio, etc. Note that the air-fuel ratio coefficient KAF is calculated based on the 02 sensor output when feedback control is performed by the 02 sensor 23, and in other cases, it is searched from a map using Alx and the engine speed as parameters. ...84 then C
The PU 30 calculates the injector valve opening times T and N by multiplying the basic valve opening time T8 by these correction coefficients.

TINJ = T8xKwtXK, XKApXKAF...
...S5 When the injector valve opening time T I N J is obtained, C
Next, in the PU 30, the high temperature increase correction coefficient setting means 43 searches for high temperature increase correction coefficients Kl and JP from the valve opening time increase rate map shown in FIG. 6, based on the fuel temperature detected by the fuel temperature sensor 17. This map was created in response to the high temperature characteristics of the injector (graph in Figure 5), and as the injector valve opening time T I N J increases, the high temperature increase correction coefficient K for each temperature increases. 2 is becoming smaller. Therefore, as in conventional injection control, extra fuel increase correction that causes overrich is not performed, and if the actual fuel temperature is not on the map, complementary calculation is performed. ...S6 Once the high temperature increase correction coefficient KUP is obtained, the CPU 30 then multiplies it by the injector valve opening time T + NJ.

T INJ = T INJ
...57 In the CPU 30, the invalid time correction value setting means 45 next sets the invalid time correction value T of the injector 12 based on the signal from the battery sensor 44 that detects the battery voltage. Calculate.

Add to injector valve opening time TINJ.

T INJ = T INJ + To ・
. . . 38 or more, the calculation of the injector valve opening time in the normal operation mode is completed, and injection is executed based on the signal from the crank angle sensor 24.

On the other hand, if the start mode is determined in S2, the CPU
At 30, the starting basic valve opening time setting means 46 sets the starting basic valve opening time T, . The basic valve opening time for starting Ts is uniquely set based on the water temperature, and no corrections like those in S4 are made...S9 Once the basic valve opening time for starting T and A is set, the CPU 30 performs the following steps. Replace this with the injector valve opening time T I N J.

T1NJ=Tsd...S10 Injector opening time TINJ is calculated, CPU3
0, then S5. The process of S6 is performed and injection is executed in the same manner as in the normal operation mode.

In this embodiment, the high temperature increase correction coefficient KUP is determined from the valve opening time increase rate map, which uses the fuel temperature and the injector valve opening time as parameters. Even in such cases,
If the valve opening time is not increased unnecessarily, drivability may deteriorate due to over-richness, and harmful components (
HC, Co, etc.) is now prevented from increasing.

<Effects of the Invention> According to the present invention, injector drive control is performed using a valve opening time increase rate map that uses fuel temperature and injector valve opening time as parameters. Regardless of the situation, it is possible to always inject the appropriate amount of fuel.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing the entire control system in an embodiment of the present invention, and FIG. 2 is a hardware configuration diagram of an electronic control unit. 3 and 4 are a control flowchart and a control block diagram, respectively, and FIGS. 5 and 6 are a graph showing the high temperature characteristics of the injector and a valve opening time increase rate map, respectively. In the figure, E is the engine, 2 is the injector, 7 is the fuel temperature sensor, 9 is the ECU, 0 is the CPU, 9 is the starting mode determination means, 0 is the A/N calculation means, 1 is the basic valve opening time setting means, 2 3 is a correction coefficient setting means, 3 is a high temperature increase correction coefficient setting means, 5 is an invalid time correction value setting means, and 6 is a starting basic valve opening time setting means. Figure 3

Claims (1)

[Scope of Claims] An injector whose fuel injection amount is determined by a valve opening time, a fuel temperature detection means for detecting a fuel temperature in a fuel pipe, a detection result of the fuel temperature detection means and a valve opening time of the injector. A valve opening time increase rate map with a parameter as the valve opening time increase rate map, and a valve opening time increase rate is searched from this valve opening time increase rate map, and then, the valve opening time is multiplied by this valve opening time increase rate to drive the injector. An electronic fuel injection device characterized by comprising a drive control means for performing control.