JP3876568B2 - Electronic fuel injection control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electronic fuel injection control device, and more particularly to an electronic fuel injection control device of a feedback control system immediately after completion of engine start.
[0002]
[Prior art]
FIG. 5 shows a configuration example of a conventionally known electronic fuel injection control device, and particularly shows a control system related only at the time of engine start and completion. In the figure, reference numeral 1 denotes an engine speed sensor (not shown), and reference numeral 5 denotes a water temperature sensor of the engine.
[0003]
Output signals of these sensors 1 and 5 are given to a controller (ECM) 2 as computing means, and a fuel injection amount Q computed by the controller 2 is given to an injector (not shown) via an injector driving unit 3. It is supposed to be.
An arithmetic algorithm of the controller 2 in such an electronic fuel injection control apparatus is shown in FIG. 6, and the controller 2 includes arithmetic units 11 and 14 and a selector 13 as shown in FIG. . The calculation unit 11 calculates the fuel injection amount at the start by inputting the engine speed RPM from the engine speed sensor 1 and the water temperature Tw from the water temperature sensor 5 when starting the engine by starter driving.
[0004]
The calculation unit 14 also inputs the engine speed RPM and the water temperature Tw at the start, and calculates the idle injection amount immediately after the engine start is completed.
Then, the selector 13 selects the fuel injection amount calculated by the calculation unit 11 when starting the engine based on the engine speed and the like, and selects the fuel injection amount calculated by the calculation unit 14 in the idle state immediately after the completion of engine start. And output as a fuel injection amount Q.
[0005]
In FIG. (2) is arithmetic algorithm of the arithmetic unit 14 is shown, speaking the algorithm put, fuel injection corresponding to the water temperature Tw in the accelerator = 0 as shown in the memory map of FIG. (3) The amount Q is corrected by the PI feedback calculation unit 20. Such PI control of the fuel injection amount itself is disclosed in JP-A-8-114142, JP-A-9-14031, JP-A-7-29738, and the like.
[0006]
That is, in this correction, the calculation unit 20 obtains the PI (proportional integral) feedback control calculation for the difference between the actual engine speed RPM and the target speed DRPM set in the calculation unit 14 in advance. The value obtained by subtracting the fuel injection amount Q (p, i) (which is obtained by obtaining and adding the P term and I term) from the fuel injection amount Q obtained based on the memory map shown in FIG. It is obtained as an idle fuel injection amount Q (idle) immediately after the start is completed.
[0007]
[Problems to be solved by the invention]
As described above, in the conventional electronic fuel injection control apparatus with feedback control, control using the memory map shown in FIG. 6 (3) is performed until the idle state immediately after the completion of engine start is stabilized. When the temperature is low, the fuel injection amount adjustment portion of the memory map almost depends on the water temperature.
[0008]
The response of the temperature change is slow, as a result, the initial value of the I term at the time of starting the engine in the arithmetic unit 20 shown in FIG. (2) is substantially "0", thus the initial correction amount of the I term (P term) Is substantially “0”, the fuel injection amount Q obtained from the memory map in FIG. 3 (3) is not substantially corrected, and a large fuel injection amount Q at a low water temperature is given to the injector drive unit 3 as it is. End up.
[0009]
This is the same when the signal line of the water temperature sensor 5 is disconnected.
Therefore, due to such a response delay of the water temperature change and disconnection of the water temperature sensor, the amount of fuel injection with respect to the idle state immediately after the completion of the engine start increases, and the engine speed falls into a poorly controlled state such as engine blow-up. There was a problem.
[0010]
Accordingly, an object of the present invention is to realize an electronic fuel injection control device of a feedback control system that can supply a stable fuel injection amount immediately after completion of engine start.
[0011]
[Means for Solving the Problems]
In order to achieve the above object, an electronic fuel injection control device according to the present invention includes a memory map stored in advance based on an engine speed detecting means, a battery voltage detecting means, an engine speed and a battery voltage when the engine is started. And calculating means for calculating an idle fuel injection amount immediately after completion of engine start using the initial value obtained from the initial value of the PI feedback control I value corresponding to the friction force. It is characterized by.
[0012]
That is, in the present invention, in order to eliminate a control delay of the fuel injection amount due to a delay in response to a change in the water temperature or disconnection of the water temperature sensor, feedback control of the fuel injection amount is performed without using the water temperature as a parameter.
That is, without using the memory map shown in FIG. 6 (3), PI feedback control is executed based on the difference between the target engine speed DRPM and the actual engine speed RPM immediately after the engine is started, that is, immediately after the engine starts. To do.
[0013]
At this time,
Qi = Qi0 + KiΣ (DRPM-RPM) (Ki is a constant) Expression (1)
The initial value Qi0 of the I (integral) term of the fuel injection amount given by is obtained from the engine speed and the battery voltage at the time of engine start (before the start is completed), and this initial value Qi0 is substituted into the equation (1). The calculation means outputs the fuel injection amount Q including the fuel injection amount Qi (and the fuel injection amount Qp of the P term) as the idle fuel injection amount immediately after the engine start is completed.
[0014]
Thus, the reason why the initial value Qi0 of the I term of the fuel injection amount is obtained from the engine speed and the battery voltage when starting the engine is as follows.
The engine speed given by the fuel injection amount Qi by the I term in the PI control is inversely proportional to the frictional force of the engine when the accelerator = 0 (idle state). Further, this frictional force is influenced by the oil temperature (that is, the water temperature) and the intake pressure (inverse relationship). However, since the intake pressure is a negligible parameter, the frictional force is substantially affected by the water temperature.
[0015]
Therefore, the I term can be initialized as a function of the water temperature.
However, as described above, when the water temperature is used as a parameter, poor control of the fuel injection amount is caused.
On the other hand, since it is known that the engine speed at the time of starting the engine is determined by the battery voltage and the frictional force, if the frictional force influenced by the water temperature is used as an alternative to the water temperature, the engine speed at the time of starting the engine Obtaining the frictional force with the battery voltage is equivalent to obtaining the I term indirectly using the water temperature.
[0016]
Therefore, the calculation means can execute stable fuel injection amount control by using the I term obtained from the frictional force as the initial value of the fuel injection amount.
The calculation means preferably uses the value at the start of injection at the start as the engine speed.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows a configuration of an embodiment of an electronic fuel injection control device according to the present invention, and this configuration particularly shows a configuration after the engine is started as in FIG. However, as can be seen by comparing FIG. 1 and FIG. 5, in the electronic fuel injection control apparatus according to the present invention, the controller 2 always monitors the voltage of the battery 4 instead of the water temperature sensor 5 shown in FIG. The point is different.
[0018]
FIG. 2 shows the calculation algorithm of the controller 2 shown in FIG. 1. As can be seen from comparison with the calculation algorithm shown in FIG. 6, the calculation unit 11 is the same as shown in FIG. However, the calculation unit 12 is different from the calculation unit 14 of FIG. 6A in that the water temperature Tw and the engine speed RPM are input, whereas the battery voltage Vb at the start of the engine and the engine speed RPM at the start of the engine. The point that is input is different.
[0019]
As shown in FIG. 2 (2), the battery voltage Vb and the engine are determined by the memory map 21 also shown in FIG. A fuel injection amount Qi0 as an initial value of the I term of PI control is obtained from the rotational speed RPM.
[0020]
Further, as shown in FIG. 2B, the PI feedback calculation unit 22 inputs the difference between the target rotational speed DRPM and the actual rotational speed RPM and the initial value Qi0 obtained by FIG. The idle injection amount Q immediately after the completion of the engine start is calculated according to the above equation (1).
[0021]
Here, the battery voltage Vb is a value detected by the controller 2 (1) when the starter (motor) is driven before the engine start is completed as shown in FIG. As for the number RPM, the value at the time of starter driving (preferably at the start of injection) is detected ((2)) among the detection signals of the sensor 1 as shown in FIG. The idle injection amount immediately after is calculated.
[0022]
FIG. 4 shows a graph for creating a memory map of the battery voltage Vb, the engine speed RPM, and the initial fuel injection amount Qi0 shown in FIG.
That is, in the idling state where accelerator = 0, the engine speed is inversely proportional to the engine frictional force, and the engine speed increases as the battery voltage Vb increases.
[0023]
Therefore, when these three parameters are plotted together, the result is as shown in FIG.
Here, when the water temperature is low, the oil temperature is low and the viscosity is high, and the frictional force is high. Therefore, the frictional force and the water temperature can be viewed as an inverse (inversely proportional) relationship in FIG.
[0024]
Therefore, if the graph with the frictional force (in other words, the water temperature) shown in FIG. 1 (1) as a parameter is plotted with the battery voltage Vb as a parameter, the engine rotational speed against the frictional force is shown in FIG. 2 (2). It can be seen that it is shown to be inversely proportional.
[0025]
When the graphs shown in FIGS. 1A and 1B are expressed in three dimensions, the result is shown in FIG. 3C , which can be used as the memory map shown in FIG. become. For example, if the engine speed RPM is RPM1 and the battery voltage Vb is Vb1, the fuel injection amount Qi01 as the initial value of the I term of PI control corresponding to the frictional force is obtained.
[0026]
In the above embodiment, the diesel engine is described as an example of the engine. However, the present invention is not limited to this, and the concept of the present invention can be applied to a gasoline engine.
[0027]
【The invention's effect】
As described above, according to the electronic fuel injection control apparatus according to the present invention, the fuel injection amount obtained from the memory map obtained in advance based on the battery voltage and the engine speed at the time of engine start corresponds to the frictional force PI. Since the initial value of the I term of the feedback control is obtained and the idle fuel injection amount immediately after the completion of the engine start is calculated using this initial value and the fuel injection control is performed, the initialization of the I term initializes the water temperature sensor. It is possible to eliminate the influence and start the engine smoothly and stably.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of an embodiment of an electronic fuel injection control device according to the present invention.
FIG. 2 is a diagram for explaining a calculation algorithm of a controller in the electronic fuel injection control apparatus according to the present invention.
FIG. 3 is a diagram for explaining a detection time point of a battery voltage and an engine speed in the electronic fuel injection control apparatus according to the present invention.
FIG. 4 is a graph for explaining a memory map used in the electronic fuel injection control apparatus according to the present invention.
FIG. 5 is a block diagram showing a configuration example of a conventional electronic fuel injection control device.
6 is a diagram for explaining an arithmetic algorithm in the controller of the conventional example shown in FIG. 5. FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Engine speed sensor 2 Controller 3 Injector drive part 4 Battery 5 Water temperature sensor 11, 12, 14 Calculation part 13 Selector 20, 22 PI feedback calculation part 21 In a memory map figure, the same code | symbol shows the same or an equivalent part.

Claims (2)

A fuel injection amount obtained from an engine speed detection means, a battery voltage detection means, a memory map stored in advance based on the engine speed and battery voltage at the time of starting the engine, and an I value of PI feedback control corresponding to the friction force An electronic fuel injection control device, comprising: an arithmetic unit that obtains an initial value and calculates an idle fuel injection amount immediately after completion of engine start using the initial value . In claim 1,
The electronic fuel injection control apparatus characterized in that the calculation means uses a value at the start of injection at the start as the engine speed.

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