JPS5825533A - Fuel injection method and device of electronically controlled engine - Google Patents

Abstract

PURPOSE:To permit asynchronous injection to effectively act on ignition quality, by arranging both starting synchronous injection quantity and asynchronous injection quantity at starting to a function of cooling water temperature while synchronizing asynchronous injection at starting with a crank angle. CONSTITUTION:In a starting condition when speed of an engine is, for instance, less than 500rpm, a starting synchronous injection time tauSTR in accordance with cooling water temperature is read from a ROM66 memory map in a control circuit 50. While an asynchronous injection time tau'STA is obtained by multiplying a prescribed coefficient A to a synchronous injection time tauSTA and stored to a RAM68. Synchronizing with a 30 deg.CA signal, following the initial cylinder decision signal, firstly when the engine is rotated by the 30 deg.CA from the top dead center of a prescribed cylinder, injection of the asynchronous injection time tau'STA is executed. Then in case of synchronous injection timing, for instance, 60 deg.CA before the top dead center, injection of the synchronous injection time tauSTA is executed. In this way, good startability of the engine can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel injection method and device for an electronically controlled engine, which is suitable for use in special traps and automatic military engines, and is calculated according to the intake air amount and engine rotation speed of the engine. By adding corrections to the basic fuel injection amount according to engine conditions, etc., fuel is synchronously injected in synchronization with engine rotation, and a predetermined amount of fuel is injected asynchronously when a signal is detected, depending on the engine operating condition. This invention relates to improvements in fuel injection methods and devices for electronically controlled engines.

One method of supplying a predetermined mixture of fuels to the combustion chamber of an internal combustion engine (referred to as an engine) is to use a so-called electronically controlled fuel injection device.

In this method, an injector for injecting fuel into the engine is installed in the intake manifold or throttle body of the engine, for example, in several engine cylinders or in one engine cylinder, and the opening time of the injector is adjusted depending on the operating state of the engine. By controlling this, an air-fuel mixture with a predetermined air-fuel ratio is supplied to the engine combustion chamber. There are various types of such electronically controlled fuel injection devices, but in recent years, particularly, digital electronically controlled fuel injection devices in which the electronic control circuit has been digitalized have been developed. In such an electronically controlled fuel injection system, the amount of intake air in the engine is usually calculated using an air flow meter, etc., and the engine speed is detected from the engine speed signal input from the distributor. By adding corrections to the basic fuel injection amount using signals according to the engine status, etc. input from nine sensors installed in each part of the engine, synchronous injection always injects at the same crank position in synchronization with engine rotation, and startability. Or acceleration [? ! In order to improve the responsiveness of the engine, in addition to normal synchronous injection, asynchronous injection is performed in which a predetermined amount of injection is performed only immediately after a sensor signal is received in accordance with the driving condition.

The synchronous injection time during which the injector is open in response to the synchronous injection is, for example, the amount of intake air from the airflow meter and the basic injection time calculated using the rotation signal from the +7 viewer. By the signal
Determined by multiplying the injection time by a correction coefficient to correct the injection time according to the engine condition at that time, such as when cold or accelerating, and further adding the invalid injection time to correct the injector operation delay due to voltage fluctuations. This is it. For example, in order to improve engine startability, the basic injection time is corrected at the time of engine startup by setting it as a predetermined time regardless of the intake air amount and engine speed when starting the engine. In order to stabilize the engine, the amount is increased for a certain period of time after the engine starts, and the amount is corrected after starting.Furthermore, when the intake air amount is low, the air density becomes thick (and the air-fuel ratio In order to prevent deviation, the amount of intake air is increased when it is low to correct the intake air temperature, and to ensure drivability in cold conditions, the amount is increased when the cooling water temperature is low to correct the intake air temperature. (5) In order to prevent sluggishness immediately after acceleration and improve acceleration performance, the amount of acceleration wvko is increased for a certain period of time.
The acceleration increase is corrected during warm-up, and in order to increase the engine output at high loads, the output increase is corrected by increasing the throttle valve opening at high loads such as 60 degrees or more. Air-fuel ratio feedback correction is performed by setting the air-fuel ratio to a predetermined air-fuel ratio, for example, near the stoichiometric air-fuel ratio, and changing the increase ratio according to the oxygen concentration in the exhaust gas. In addition, to prevent overheating of the catalytic converter and save fuel consumption, or to forcefully suppress the vehicle speed, fuel injection is stopped and fuel cut when the engine brakes or when the speed exceeds military speed or the specified maximum speed. On the other hand, the asynchronous injection is controlled independently of the synchronous injection, and for example, when starting the engine, cranking is prolonged until synchronous injection is performed. To improve startability (as above), inject twice at the same time as the ignition switch signal is detected, and to improve responsiveness immediately after acceleration (6), the throttle valve fully closed signal changes from on to off. Once when switching to , once when the next acceleration signal is input, and furthermore, the input interval of the acceleration signal is a predetermined time, for example, 200 f IJ
1 every time an acceleration signal is input during sudden/medium leg speeds of less than a second.
In order to improve responsiveness when returning from fuel cut, the throttle valve is opened at the time of fuel cut, the throttle valve fully closed signal is turned off, and fuel cut is canceled. It is designed to be injected once at a time.

Such an electronically controlled fuel injection device, particularly a digital electronically controlled fuel injection device, is characterized in that it is possible to control the fuel injection amount extremely precisely.

However, in such an electronically controlled fuel injection system, conventional asynchronous injection at the time of starting is a method that always injects a fixed amount of fuel at the same time as the ignition switch signal is detected. The amount of fuel injected remains constant regardless of changes in temperature, and when the temperature is extremely low, the amount of injection is insufficient, resulting in poor starting performance.On the other hand, at high or normal temperatures, the amount of fuel injected is too large, resulting in poor exhaust gas purification performance. Otherwise, the air-fuel mixture may become too rich, resulting in poor starting performance.

Furthermore, in the past, regardless of the crank angle of the engine, depending on the angle, the injection was not effective for improving ignitability, and the asynchronously injected fuel adhered to the wall of the intake i-nifold, which could actually impair starting performance. Sometimes things got worse.

The fIA of the present invention was developed to eliminate the above-mentioned conventional drawbacks, and can provide appropriate synchronous injection amount and asynchronous injection amount at startup depending on the engine condition. Effectively affects sex,
An object of the present invention is to provide a fuel injection method and device for an electronically controlled engine that can improve startability.

The present invention adds correction according to the engine condition to the basic fuel injection amount calculated according to the intake air amount and engine speed of the engine, and injects fuel synchronously with the engine rotation. In a fuel injection method for an electronically controlled engine, in which a predetermined amount of fuel is asynchronously injected when a signal is detected, depending on the engine operating state, both the starting synchronous injection amount and the asynchronous injection amount at the time of engine startup are controlled by the engine cooling water temperature. In addition, the asynchronous injection at the time of engine startup is performed in synchronization with the crank angle, thereby achieving the above objective.

Further, the amount of asynchronous injection at the time of starting the engine is determined from the amount of synchronous injection at the time of starting.

Alternatively, the asynchronous injection at engine startup is performed when the engine first rotates by a predetermined crank angle from the top dead center of a predetermined cylinder.

Furthermore, an intake air amount sensor for detecting the intake air amount of the engine and a crank angle sensor for detecting the engine crank angle and engine rotation speed are used to determine the fuel injection time of the electronically controlled engine in which the method is carried out. A cooling water temperature sensor that detects the engine cooling water temperature, a starting sensor that detects when the engine is starting (9), an injector that injects fuel into the engine, and a The synchronous injection time is obtained by adding corrections according to the engine condition etc. to the basic fuel injection time calculated according to the engine speed. On the other hand, when starting the engine, the synchronous injection time at startup is a function of the engine cooling water temperature. At the time of starting the engine, the asynchronous injection time is determined from the synchronous injection time at startup, and when the engine is started, the engine initially moves from the top dead center of the specified cylinder to the specified crank angle. and an electronic control circuit that outputs an asynchronous injection signal to the injector so that asynchronous injection is performed when the injector is rotated by an angle.

Embodiments of the present invention will be described in detail below with reference to the drawings.

An embodiment of an electronically controlled engine in which the fuel injection control method for an internal combustion engine according to the present invention is adopted is as shown in FIGS. 1 and 2.
An air flow meter 16 for detecting the intake air amount of the engine, and an intake temperature sensor 18 disposed within the air flow meter 16 for detecting the intake air temperature, are disposed on the downstream side. It is built into the distributor 20 which has a shaft 20a'j!- which rotates according to the engine rotation, and according to the engine rotation,
A pulse signal (
(referred to as 30° CA signal) t-generating crank angle sensor 22, a coolant temperature sensor 26 disposed in the engine block 24 for detecting the engine coolant temperature, and an accelerator disposed in the intake passage 12. A throttle position sensor 30 detects the opening degree and opening change speed of the intake throttle valve 28, which opens and closes in conjunction with the pedal; an ignition switch 31 generates a starter signal during engine startup; Oxygen concentration that detects residual oxygen in the catalyst inflow gas flowing into the catalytic converter 34 filled with a catalyst, for example, a three-way catalyst, which is disposed downstream of the exhaust manifold 32 where exhaust gas is formed. A sensor 36, a vehicle speed sensor 40 for detecting the running speed of the vehicle, that is, vehicle speed from the rotational speed of the output shaft of the transmission 38, and an injector 44 for injecting fuel into the intake manifold 42 of the engine 1o. Intake passage 12
An idle rotation speed control valve 48 consisting of a pulse motor, an electromagnetic actuated valve, etc. is disposed in a surge tank 46 in the middle of the engine, and is used to control the flow rate of air that bypasses the intake throttle valve 28 during idle. , the synchronous injection time is obtained by adding corrections according to the engine condition etc. to the basic fuel injection time calculated according to the engine intake air amount and engine speed. The time is determined as a function of the engine cooling water temperature, and a synchronous injection signal is output to the injector 44. At the time of starting the engine, the asynchronous injection time is determined from the synchronous injection time at startup, so that the engine is in the
The injector 4 is configured so that asynchronous injection is performed when the Wr constant air tuna rotates by a predetermined crank angle from the top dead center.
4 and an electronic control circuit 50 that outputs an asynchronous injection signal. In FIG. 1, 52 is a spark plug, and in FIG. 2, 54 is a battery.

As shown in detail in FIG. 2, the digital electronic control circuit 5o converts analog signals from the air flow meter 16, intake temperature sensor 18, cooling water temperature sensor 26, oxygen 112 sensor 36, and battery 54 into digital signals. In order to do this, the digital signals from the outputs of the crank angle sensor 22, throttle position sensor 30, and ignition switch 31 are input to an analog-to-digital converter 6o having a multiplexer function, and the calculation results are input to the injector 44 and idle rotation speed. An input/output interface circuit 62 having a buffer 1 function that converts the signal into a signal suitable for being applied to the control valve 48, a central processing circuit 64 including a crystal oscillator 64a, and a read-only memory 66.
It consists of a random access memory 68 and a random access memory 70 for power supply buffer lag.

The operation will be explained below. First, in a normal state after engine starting (13) where the engine rotational speed is, for example, 500 rpm or more, the digital electronic control ii] circuit 5
0 calculates the basic fuel injection time 'rp using the following equation based on the intake air amount Q of the air 7a-meter 16 output and the engine rotation speed N calculated from the output direction of the crank angle sensor 22.

Here K is a coefficient.

Furthermore, the synchronous injection time τ1 is calculated by correcting the basic injection time Tp using the following equation according to the signals from each sensor.

' t-Tp @f (A/P) "f (WL) ・
,f (THA)x(1+/(A8K)+f(AIW
) + / (OTP) ) X (1 go (R8))...
・・・・・・・・・(2) Here, /(A/F) is the air-fuel ratio feedback correction coefficient, f(WL
) is the warm-up increase correction coefficient, /(THA) is the intake temperature correction coefficient, f (A8g is the starting 4; &dantm positive coefficient, f (MUEW)
) is the warm-up acceleration increase correction coefficient, /(OTP) is the overheat (output) increase coefficient, and f (R8) is the reduction coefficient.

On the other hand, when the engine (b) rotational speed is, for example, 500 rpm (14) in the engine starting state, the off 1J-memory (17+) of the digital electronic control circuit 50 is off as shown in FIG. The engine cooling water temperature and the starting synchronous injection time t, as shown in FIG.
sT input relationship is fl:, 7''- From the pull, the starting synchronous injection time τ8TAt- according to the engine cooling water temperature is read out and set as the synchronous injection time t.

Furthermore, the asynchronous injection time t'8Tk at engine startup in this embodiment is determined as follows.

That is, first, the output of the ignition switch 31 is determined in the main routine as shown in FIG. From the relationship between the engine cooling water temperature and the starting synchronous injection time τ8TA as shown in the figure, the starting synchronous injection time rsTA corresponding to the engine cooling water temperature at that time is read out. Next, the read start synchronous injection time faTA
By multiplying by a predetermined coefficient At, the asynchronous injection time t'BTkf at engine startup is determined. This starting asynchronous injection time τ'ST A is stored in the random access memory 68 of the digital electronic control circuit 50, and an asynchronous injection execution flag is set.

Next, another main routine is executed, and this main routine is not executed thereafter until the ignition switch is turned off.

Next, the actual injection process is performed as follows. That is, as in the 30'CA interrupt routine shown in FIG.
First, by detecting and latching the 30'CA signal output from the crank angle sensor 22, and then shifting the 30°CA counter by one position to the left, one counter will be set to 30°C.
Make it the A signal. Next, it is determined whether the 30° C^ counter is O or not, and if it is 0, the content of Kara/R is set to 1, and this becomes the top dead center. 51! Then, the cylinder discrimination signal is latched and the cylinder discrimination signal is determined. When the cylinder discrimination signal is output, when the number of cylinders is the predetermined cylinder, it is determined whether or not the starter signal is input, that is, whether or not cranking is in progress.

If cranking is in progress with the starter signal being input, the state of the asynchronous injection execution flag is determined, and if the asynchronous injection execution flag is set, the 30°C that follows the first generous determination signal is determined. In synchronization with the signal, when the engine first rotates by 306 CA from the top dead center of a predetermined cylinder, injection for the asynchronous injection time τ'S T A is executed, and the asynchronous injection execution flag is reset. On the other hand, if the asynchronous injection execution flag has been reset, it is determined whether or not it is the synchronous injection timing based on the contents of the 30° CA counter. If the injection timing is synchronous, for example, 60° CA before the top dead center, injection for the synchronous injection time τ is performed, whereas if it is outside the synchronous injection timing, the synchronous injection is not performed.

In this embodiment, since the asynchronous injection amount at engine startup is the synchronous injection time at startup, there is no need to re-memorize a table to fit the relationship t between the engine cooling water temperature and the asynchronous injection amount at engine startup. Memory capacity can be reduced (17).

Furthermore, in this embodiment, the asynchronous injection at the time of engine startup is performed when the engine has rotated by 30@CA from the top dead center of a predetermined cylinder. Either the synchronous injection performed at 60°CA before the intake stroke is effectively executed and the asynchronous injection is ignored as a synchronous injection, or the asynchronous injection is performed after the intake stroke and the fuel is It will not stick to the inside of the intake manifold, etc.

As explained above, according to the present invention, asynchronous injection is performed with an appropriate asynchronous injection amount according to the engine cooling water temperature and an appropriate injection timing according to the crank angle, so that the injection is performed smoothly regardless of the engine condition. This has the following excellent effects: a good engine startability can be obtained, and smoldering of the spark plug due to over-richness does not occur.

[Brief explanation of the drawing]

Eleventh, how is the electronically controlled engine equipped with the fuel injection method according to the present invention? Figure 2 is a cross-sectional view including a partial professional (18) diagram showing lJ, and Figure 3 is a block diagram showing the circuit configuration of the digital electronic side circuit used in the above embodiment. is a flowchart showing a fuel synchronous injection time calculation routine in the embodiment, and 4th rA is a diagram showing the relationship between engine cooling water temperature and startup synchronous injection time, which is used in the synchronous injection time calculation routine. 8
FIG. 5 is a flowchart showing the asynchronous injection time calculation routine in the embodiment, and FIG. 6 is a flowchart showing the ninth 30° CA 11111 routine of fuel injection execution in the embodiment. 10.・Engine, 16...Air 70-meter, 2
0...Taste distributor, 22...Crank angle sensor, 26...Cooling water mud sensor, 31...Ignition switch, 42...Intake manifold, 44...Injector, 50...Digital electronic side - circuit. Agent Takaya Ron (and 1 other person) (19) Tea 3 Fig. v75 Fig. #74 Fig. Engine cold water p water jJ [Fig. 6

Claims (4)

[Claims] (1) The basic fuel injection amount, which is calculated according to the engine intake air amount and engine speed, is corrected according to the engine condition, etc., and the fuel is synchronized with the engine speed.
In a fuel injection method for an electronically controlled engine in which a predetermined amount of fuel is injected asynchronously when a signal is detected in accordance with the engine operating state, both the starting synchronous injection amount and the asynchronous injection amount at the time of engine startup are A fuel injection method for an electronically controlled engine, characterized in that the injection is made as a function of the engine cooling water temperature, and the asynchronous injection at the time of engine startup is performed in synchronization with the crank angle. (2) The fuel injection method for an electronically controlled engine according to claim 3g1, wherein the asynchronous injection amount at the time of engine startup is set to be *4 less than the synchronous injection amount at startup. (3) The asynchronous injection at the time of starting the engine is performed when the engine is first rotated by a predetermined crank angle from the top and bottom of a predetermined cylinder. The fuel injection method for an electronically controlled engine according to item 1 or 2. (4) An intake air volume sensor that detects the intake air amount of the engine, a crank angle sensor that detects the engine crank angle and engine speed, a cooling water temperature sensor that detects the engine cooling water temperature, and an engine There is a starting sensor that detects that the engine is starting, an injector that injects fuel into the engine, and a basic fuel injection time that is calculated according to the engine intake air amount and engine speed. On the other hand, when starting the engine, the synchronous injection time at startup is calculated as a function of the engine cooling water temperature, and a synchronous injection signal is output to the injector, calculates the asynchronous injection time from the synchronous injection time at startup described in 11J, and injects the injector with the asynchronous injection so that the asynchronous injection is performed when the engine first rotates by a predetermined crank angle from the top dead center of a predetermined cylinder O at the time of engine startup. A fuel injection device for an electronically controlled engine, comprising: an electronic control circuit that outputs a signal.