JPS61142345A - Method of controlling amount of starting fuel in fuel injection type engine - Google Patents

Abstract

PURPOSE:To ensure always a satisfactory starting ability of an engine which carries out asynchronous fuel injection upon starting without deteriorating the exhaust purification performance and fuel consumption performance of the engine, by determining the amounts of first to third asynchronous fuel injections in accordance with the temperature of an engine. CONSTITUTION:Upon starting of an engine, an ECU56 judges whether the temperature Tw of cooling water which is detected by a water temperature sensor 46 upon judgment of starting of the engine by a starter 54, is within a set limit range or not, or whether it is above a lower limit value T1 which is set lower than and in the vicinity of the operation starting temperature of a cold start injector 42 but below an upper limit T2 which is in the vicinity of the temperature of cooling water after completion of warm-up operation, or not. If Tw<=T1, the asynchronous fuel injection amount of a main injector 44 is determined in accordance with a first value premizing that the injector 42 is operated. Further, when the temperature of cooling water is within the above-mentioned set range, the asynchronous fuel injection amount is determined in accordance with a second value premizing that the injector 42 will not operated, and if Tw>=T2, asynchronous fuel injection amount is determined in accordance with a third value.

Description

[Detailed description of the invention] [Industrial application field]

The present invention provides starting fuel 111tl11 for a fuel injection engine.
The method relates to a starting fuel control for a fuel injection engine in which asynchronous injection is performed by the main injector at the time of engine starting, which is particularly suitable for use in an electronically controlled fuel injection engine for automobiles equipped with a main injector and a cold start injector. Concerning improvements in methods.

[Conventional technology]

If the engine temperature is low when starting the engine, there is not enough heat in the intake boat, resulting in poor fuel atomization. Or
Due to reasons such as high friction due to low lubricating oil temperature, more fuel is required after the engine has warmed up. However, if more fuel is supplied than necessary, problems may occur such as the spark plug becoming clogged, making it impossible to start, increasing the amount of unburned components in the exhaust gas, and deteriorating fuel efficiency. In order to solve these problems, an injector with improved fuel atomization, a so-called cold start injector, is attached to the surge tank and is operated below a specific engine coolant temperature.The lower the engine coolant temperature, the more fuel is injected. It is proposed to do so. Also 6 For example, Japanese Patent Application Publication No. 5
As disclosed in 5-153831 and JP-A-57-157028, when the starter is driven, the so-called synchronous injection amount, in which fuel is injected in synchronization with engine rotation, can be increased as the engine cooling water temperature is lower. Proposed. Furthermore, as disclosed in Japanese Patent Application Laid-Open No. 58-25533,
It has been proposed to perform so-called asynchronous injection, which injects fuel regardless of the engine speed when starting the engine.

[Problems to be solved by the invention]

However, even if the above methods are combined and slightly adapted, it is difficult to ensure starting performance over the entire engine cooling water temperature range while still satisfying exhaust gas purification performance. The problem was that the starting performance was insufficient in this region.

[Purpose of the invention]

The present invention was made to solve the above-mentioned conventional problems, and provides a fuel injection engine that can ensure starting performance over all engine temperature ranges without impairing exhaust gas purification performance or fuel efficiency. An object of the present invention is to provide a starting fuel control method.

[Means to solve the problem]

The present invention provides a starting fuel control method for a fuel injection engine in which asynchronous injection is performed by a main injector at the time of engine starting, as summarized in FIG.
A procedure for detecting engine temperature, a means for detecting that the engine is starting, a procedure for comparing engine temperature with a set range, and setting the engine temperature near and below the operating temperature of a cold start injector. When the engine temperature is lower than the lower limit of the set range, the asynchronous injection amount is determined by the first value assuming operation of the cold start injector, and when the engine temperature is within the set range, 1. A procedure for determining the asynchronous injection amount by a second value greater than the first value, assuming that the cold start injector is not activated, and when the engine temperature is at am
By including a step of determining the asynchronous injection amount by a third value smaller than the second value when the temperature is higher than the upper limit of the setting range, which is set near the engine temperature after the end,
The above objective has been achieved. In addition, Mr. W/AWA of the present invention changed the first value to the third value.
The control is simplified by matching the value of . (Function) When the present invention performs asynchronous injection by the main injector at engine start, when the engine temperature is near the operation start temperature of the cold start injector and lower than the lower limit of the setting range, The asynchronous injection amount is determined by a first value assuming that the cold start injector is in operation, and when the engine temperature is within the set range, the amount is determined from the first value, which is based on the assumption that the cold start injector is not operating. The asynchronous injection amount is determined by a larger second value, and when the engine temperature is higher than the upper limit of the setting range, which is set near the engine temperature after warm-up, the asynchronous injection amount is determined by a second value that is smaller than the second value. Since the asynchronous injection amount is determined based on the value of 3, starting performance can be ensured over all engine temperature ranges without impairing exhaust gas purification performance or fuel efficiency. That is, for example, below 0°C. At such low temperatures, the atomization state of the engine is poor to begin with, so no matter how much you increase the amount of fuel injected from the main injector, starting performance is very poor. Assuming that the start injector operates, the asynchronous injection amount is determined by the first value.On the other hand, there is a request to reduce the fuel injection amount as much as possible in order to reduce the HC during engine cold start. To do this, it is necessary to move the operation start temperature of the cold start injector to a lower temperature side, but in such a case, if this operation start temperature varies, the cold start injector may not operate in a certain temperature range.For example, Set the operating temperature of the cold start injector to 35
When the temperature is lowered from 0.degree. C. to 22.degree. C., the operation start temperature becomes 17.degree. C. due to variations in the cold start injector, and the cold start injector will not operate at 18.degree. Even in such a case, the first value is insufficient to guarantee a reliable start, so within the setting range, the asynchronous injection amount is set to the first value on the assumption that the cold start injector is not activated. The second value is set to be larger. Furthermore, after the engine has been warmed up, there is no need to increase the amount for low temperature measures, so asynchronous injection is performed using a third value smaller than the second value, that is, a normal value.

【Example】

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an electronically controlled fuel injection engine for an automobile to which the present invention is applied will be described in detail below with reference to the drawings. The electronically controlled fuel injection engine to which the present invention is applied has a second
It is configured as shown in the figure. In FIG. 2, air sucked from an air cleaner (not shown) is air 70-
The air is sent to the combustion chamber 10A of the engine body 10 through an intake passage including a meter 14, a throttle valve 16 linked to an accelerator pedal (not shown), a surge tank 18, an intake manifold 19, an intake boat 20, and an intake valve 22. The combustion chamber 10A is divided by a cylinder head 10/1 cylinder block 10G and a piston 12, and the exhaust gas generated by combustion of the air-fuel mixture is passed through an exhaust valve 24, an exhaust boat 26, an exhaust manifold 28, and an exhaust pipe 30. and is discharged to the atmosphere via the catalytic converter 32. A distributor 34 having a shaft rotationally driven by a crankshaft (not shown) transmits a high-pressure ignition secondary signal generated by an ignition coil 36 to a spark plug 38 of each cylinder of the engine.
It is designed to distribute electricity to The throttle valve 16 is provided with a throttle sensor 40 that detects its opening degree. Said surge tank 1
8 includes a cold start injector 4 which is opened by an independent control circuit at the time of cold start, and injects more starting auxiliary fuel as the engine cooling water temperature becomes lower.
2 are installed. The intake manifold 19
is provided with a main injector 44 that intermittently injects high-pressure fuel toward the intake boat 20. A water temperature sensor 46 using, for example, a thermistor element is disposed in the cylinder block 10G to detect the engine cooling water temperature, that is, the engine temperature. An oxygen concentration sensor (hereinafter referred to as 02 sensor) 48 that detects the residual oxygen concentration in the exhaust gas for the purpose of detecting the air-fuel ratio is disposed at the gathering portion of the exhaust manifold 28. A crank angle sensor 50 for detecting a crank angle based on the rotational state of the distributor shaft and a cylinder discrimination sensor 52 for discriminating a cylinder are disposed inside the distributor 34. These sensors 14.39.46.48.50152,
The activation signals for the ignition switch 53 and starter 54 are electronic! 'j m unit (hereinafter referred to as ECU) 56. The ECU 36 calculates fuel injection I (synchronous injection amount and asynchronous injection) using input signals from each sensor as parameters, and sends an electric pulse having a pulse width corresponding to the calculated fuel injection amount to the main injector 44. As shown in detail in FIG. 3, the ECU 36 includes a central processing module W (hereinafter referred to as CPU) 56A consisting of a microprocessor, a read-only memory (hereinafter referred to as ROM) 56B, and a random access memory (hereinafter referred to as RAM). ) 56C, an input port 560 that has a buffer function and an analog-to-digital converter (hereinafter referred to as an A/D converter) function, an output port 56E that also has a buffer function, and a common bus that connects each of the above-mentioned component devices. It is composed of 56F. The outputs of the air 70-meter 14, intake temperature sensor 39, water temperature sensor 46, 02 sensor 48, crank angle sensor 50, cylinder discrimination sensor 52, ignition switch 53, and starter 54 are input to the input boat 56B. Further, the main injector 44 is connected to the CPLI 5 via the output boat 56E.
A control command is input from 6A. The operation of the embodiment will be explained below with reference to FIG. First, when the ignition switch 53 is turned on and the ECLJ 56 is powered on, an initialization routine as shown in FIG. 4 is started. In this initialization routine, in step 110, the analog signal related to the cooling water temperature detected by the water temperature sensor 56 is converted into a digital signal by the A/D converter in the input boat 56D. Then, in step 112, the value converted into a digital signal is
Stored in M5.6G. Next, the process proceeds to step 114, where it is determined whether the starter 54 is in operation. If the determination result is positive, the process proceeds to step 116, where the engine cooling water temperature is within the set range, that is, near the operation start temperature of the cold start injector 42, and above the lower limit value T1 set lower than that, @after the end of the machine. It is determined whether or not the engine cooling water temperature is equal to or lower than an upper limit value T2 set near the engine cooling water temperature. If the determination result is negative, proceed to step 118;
The first value TAUI (common with the normal third value in this embodiment), which is based on the operation of the cold start injector 42, is set as the asynchronous injection amount, and the process proceeds to the asynchronous injection control routine. On the other hand, if the determination result in step 116 is positive,
That is, when it is determined that the engine cooling water temperature is within the set range between the lower limit value T1 and the upper limit value T2, step 120 is performed.
Then, on the premise that the cold start injector 42 is not activated, the second value TAU2, which is larger than the first (third) value TAL11, is set as the asynchronous injection amount, and the asynchronous injection I
II 'a Mil-tin proceed. Said lower limit T1 and upper limit 1i! 1 T 2 is, for example,
The lower limit Tw can be set to 15°C, and the upper limit T2 can be set to 28°C. Further, the first (third) value TAU1 and the second value TAU2
can be selected arbitrarily, but considering the effect on exhaust gas purification performance, it should be 50 milliseconds or less, for example, 10 milliseconds after a predetermined time (for example, 100 milliseconds) after the starter 54 is turned on. Preferably, one asynchronous injection is performed. Note that between the lower limit value T1 and the upper limit value 11172, the first (third
) may be continuously changed between the value TAtJ1 and the second value TAU2. On the other hand, if the determination result in step 114 is negative,
That is, when the starter 54 is not operating, the process returns to step 110 again through another control routine. This continues until the starter signal is input. Note that once asynchronous injection is performed, this asynchronous I
IIJ1 is never executed. In this embodiment, the first value of the asynchronous injection is made to match the third value, so the control is simple. Note that depending on the injection characteristics of the cold start injector 42,
It is also possible for the first value TAUI to be different from the third value.

【Effect of the invention】

As explained above, according to the present invention, it is possible to optimize the amount of asynchronous injection by the main injector at the time of startup in accordance with the injection of starting auxiliary fuel by the cold start injector. Therefore, it has the excellent effect of being able to satisfy exhaust gas purification performance, minimize deterioration in fuel efficiency, and ensure startability in all engine temperature ranges.

[Brief explanation of drawings]

FIG. 1 is a flowchart showing the gist of the starting fuel control method for a fuel injection engine according to the present invention, and FIG. 2 shows the overall configuration of an embodiment of an electronically controlled fuel injection engine for automobiles in which the present invention is adopted. A cross-sectional view including a partial block diagram shown in FIG.
The figure is a block diagram showing the configuration of the electronic control unit used in the above embodiment, and FIG. The flow shown is the same. DESCRIPTION OF SYMBOLS 10... Engine body, 14... Air flow meter, 42... Cold start injector, 44...
...Main injector, 46...Water temperature sensor, 50...Crank angle sensor, 53...Ignition switch, 54...Starter,
56... Electronic control unit (ECU), T1... Lower limit value, T2... Upper limit value, TAtJl... First (third) value, TALJ2... Second value. Figure l

Claims (2)

[Claims] (1) In a starting fuel control method for a fuel injection engine in which asynchronous injection is performed by a main injector at the time of engine starting, a procedure for detecting engine temperature, a means for detecting that the engine is starting, and an engine temperature The procedure for comparing the temperature with the setting range and the engine temperature are
Near the operating temperature of the cold start injector,
When it is lower than the lower limit of the setting range, which is set lower than that, the procedure for determining the asynchronous injection amount based on the first value assuming operation of the cold start injector, and when the engine temperature is within the setting range. The following describes a procedure for determining the non-periodic injection amount using a second value greater than the first value, assuming that the cold start injector is not activated, and an engine temperature set near the engine temperature after warm-up. , when higher than the upper limit of the setting range, the second
A method for controlling starting fuel for a fuel injection engine, comprising: determining an aperiodic injection amount using a third value that is smaller than the value of . (2) The starting fuel control method for a fuel injection engine according to claim 1, wherein the first value is made equal to the third value.