JPH01249933A - Electronically controlled fuel injection device for alcohol using internal combustion engine - Google Patents

Abstract

PURPOSE:To control air fuel ratio in acceleration to a desired value even if the concentration of alcohol in the fuel varies during acceleration, by correction- setting the additional fuel injection quantity in accordance with the concentration of alcohol after variation. CONSTITUTION:When the engine acceleration operation state is detected on the basis of the variation of the opening degree of an intake throttle valve 15 which is detected by an opening degree sensor 38, a control unit 40 sets the additional fuel injection quantity in the additional injection which is carried out separately from the normal injection, on the basis of the acceleration operation state and the concentration of alcohol which is detected by an alcohol sensor 39. Then, the additional injection is controlled according to the additional fuel injection quantity. When the concentration of alcohol is varied during the additional injection control after the setting of the additional injection quantity, the additional fuel injection quantity is correction-set in accordance with the concentration of alcohol after the variation. Therefore, a desired additional fuel injection quantity is obtained, and the air-fuel ratio in acceleration can be controlled to a desired value.

Description

[Detailed Description of the Invention] <Field of Industrial Application> The present invention relates to an electronically controlled fuel injection device for an alcohol internal combustion engine. Concerning something constructed to improve sexual performance.

<Prior Art> Conventionally, as an internal combustion engine configured to eliminate fuel response delay by performing additional injection during engine acceleration operation, for example, there has been an internal combustion engine as disclosed in Japanese Patent Laid-Open No. 60-201048. There is.

In systems that perform additional injection when the engine is accelerating, for example, acceleration is determined based on the rate of change in opening per unit time of a throttle valve installed in the intake system. If there is a cylinder in which fuel injection is being performed, additional injection is not performed, and if there is no cylinder in which regular injection is being performed, additional injection is performed in the nearest cylinder that has finished injection during regular injection. . Immediately after the subsequent regular injection, additional injection is performed a predetermined number of times to prevent the air-fuel ratio from becoming over lean during acceleration operation. Here, the additional fuel injection amount in the additional injection is set according to, for example, the opening change rate of the intake throttle valve, 9 the engine rotation speed, 1 the engine load, etc.

<Problems to be Solved by the Invention> Incidentally, in recent years, alcohol sensors have been installed to detect the alcohol concentration in fuel so that alcohol mixed fuel, which is gasoline mixed with alcohol such as methanol or ethanol, can be used as an alternative fuel to gasoline. An alcohol internal combustion engine has been proposed that includes an electronically controlled fuel injection device configured to control the fuel injection amount based on the detected value of the alcohol sensor.

In such an alcohol internal combustion engine, the stoichiometric air-fuel ratio changes depending on the alcohol concentration in the fuel, so the fuel injection amount is controlled depending on the alcohol concentration in the fuel as described above. Therefore, as mentioned above, the additional fuel injection amount should be set according to the alcohol concentration at that time even in the additional injection performed during acceleration driving, but it is necessary to set the additional fuel injection amount before actually adding it. If the alcohol concentration changes before injection ends, additional injections that do not match the changed alcohol concentration will be performed, making it impossible to perform the desired air-fuel ratio correction and impairing acceleration drivability. occurs.

In particular, in the case where the injection amount for additional injections that are performed multiple times afterward is set all at once based on the alcohol concentration at the time of acceleration determination, the change in alcohol concentration will not be affected after the additional fuel injection amount is set. Even if the alcohol concentration changes after setting the additional injection amount, additional injection will be performed corresponding to the alcohol concentration at the time of acceleration judgment, causing the air-fuel ratio to become over-lean or over-rich. There is a danger that it may turn into a nuisance.

The present invention has been made in view of the above-mentioned problems, and aims to improve the acceleration drivability of an alcohol internal combustion engine by performing additional injection control that follows the change in alcohol concentration even if the alcohol concentration changes during additional injection control. purpose.

<Means for Solving the Problems> Therefore, in the present invention, as shown in FIG. An electronically controlled fuel injection device for an alcohol internal combustion engine configured to control the fuel injection amount of regular injection performed in synchronization with engine rotation, comprising an acceleration detection means for detecting an accelerating operating state of the engine; additional injection control means for controlling the additional injection by setting an additional fuel injection amount for additional injection to be performed separately from the regular injection when an acceleration operation state of the engine is detected, based on the acceleration operation state and the alcohol concentration; An additional injection amount that, when the alcohol concentration detected by the alcohol sensor changes during additional injection control after the additional injection amount is set by the additional injection control means, corrects and sets the additional fuel injection amount in accordance with the changed alcohol concentration. A means of correction has been provided.

In such a configuration, when the acceleration detection means detects the accelerated operation state of the engine, the additional injection control means controls the acceleration operation detected by the acceleration detection means to determine the additional fuel injection amount in the additional injection performed separately from the regular injection. 1. Set based on the state and alcohol concentration detected by the alcohol sensor. Additional injection is controlled according to the set additional fuel injection amount. here,
If the alcohol concentration changes during the additional injection control after the additional injection amount is set by the additional injection control means, that is, from the time the additional fuel injection is set until the additional injection actually ends, the alcohol concentration is set at the time of acceleration determination. Since the additional fuel injection amount does not correspond to the current alcohol concentration and the desired air-fuel ratio cannot be corrected, the additional injection amount correction means corrects and sets the additional fuel injection amount in accordance with the changed alcohol concentration.

<Example> An embodiment of the present invention will be described below based on the drawings.

Figure 2 shows an outline of the system. In the figure, 1° is an engine combustion chamber, and an intake pipe 11 and an exhaust pipe 12 are connected to each other. A catalytic converter 13 is interposed at the rear end of the exhaust pipe 12. In addition, an air cleaner 1 is provided in the intake pipe 11.
The air purified in step 4 is supplied via the intake throttle valve 15. Bypass passage 1 that bypasses the intake throttle valve 15
An idle adjustment screw 17 is screwed into the idle adjustment screw 17, and the amount of air when the intake throttle valve 15 is closed to the idle opening is determined by the idle adjustment screw 17.
Adjusted by 7. Furthermore, the bypass passage 18 for idle rotation speed control that bypasses the intake throttle valve 15 has an electromagnetic idle control that is driven by a pulse signal and whose opening degree is adjusted according to its duty ratio (valve opening driving time ratio). A valve 19 is provided.

A fuel tank 20 stores alcohol mixed fuel (gasoline mixed with alcohol such as methanol or ethanol). And this fuel tank 2
A stirrer 21 is provided inside the fuel tank 20.
This is to stir the alcohol-mixed fuel inside to make it evenly concentrated. The alcohol mixed fuel in the fuel tank 20 is pumped to the fuel pump 22. Pressure regulator 23. The fuel passes through a fuel filter 24 and a fuel supply pipe 25 to reach a fuel injection valve 26. The alcohol mixed fuel that has not been injected and supplied to the fuel injection valve 26 is returned to the fuel tank 20 via the return passage 27.

An ignition plug 28 is provided in the fuel chamber 10, and an ignition coil 29. A high voltage is applied via the power distributor 3o. In addition, the exhaust pipe 12 and the intake pipe 11
An exhaust gas recirculation passage 32 is arranged between the exhaust gas recirculation (EGR)! The amount of exhaust gas recirculated to the intake side via the exhaust gas recirculation control valve 31 is controlled by the exhaust gas recirculation control valve 31.

The exhaust pipe 12 is provided with an oxygen sensor 33 that detects the oxygen concentration in the exhaust gas, which is closely related to the air-fuel ratio of the air-fuel mixture taken into the engine, and a temperature sensor 34 that detects the temperature of the catalytic converter 13. Further, a water temperature sensor 35 that detects the cooling water temperature Tw in the water jacket and a crank angle sensor 36 that detects the engine speed N are provided. Furthermore, the intake pipe 11 is provided with an intake pressure sensor 37 for detecting the intake pressure.
An opening sensor 38 for detecting the opening of the intake throttle valve 15 is provided. In this embodiment, since the acceleration operating state of the engine is detected based on the rate of change in the opening of the intake throttle valve 15, the opening sensor 38 corresponds to acceleration detection means. and,
The fuel supply pipe 25 between the fuel filter 24 and the fuel injection valve 26 is provided with an alcohol sensor 39 that detects the alcohol concentration in the fuel based on changes in capacitance or the like.

Detection signals from each of the sensors 33 to 39 are input to the control unit 40, respectively. The control unit 40 is configured to include a microcomputer configured with a CPU, ROM, RAM, Ilo, etc., and internally controls the optimum air-fuel ratio and optimum ignition timing.

A plurality of programs are stored in memory for obtaining the optimum idle speed, etc. And the control unit 40
The outputs of the idle control valve 19° and the fuel injection valve 26 are respectively
．． Power distributor 30. It is applied to the exhaust gas recirculation control valve 31.

Here, the control unit 40 controls regular injection in synchronization with engine rotation, and also controls additional injection separate from this regular injection during engine acceleration operation, resulting in fuel control delay and supply delay during acceleration operation. prevent the air-fuel ratio from becoming lean due to Such additional injection control will be explained according to the flowchart in FIG. In this embodiment, the control unit 40 also serves as additional injection control means and additional injection amount correction means.

First of all, the step (designated as "S" in illustration).

(Similarly below) In step 1, it is determined whether the engine is in an accelerated operating state based on the change in the opening of the intake throttle valve 15 detected by the opening sensor 38. The opening degree of the intake throttle valve 5 is
For example, sampling is performed every 10 m5, and when the amount of change in opening degree in a predetermined unit time such as 30, 50, 100 m5, etc. is equal to or greater than a predetermined value on the open side, the accelerating operation state is determined.

In step 2, additional fuel injection amount T?
As shown in Table 1, the acceleration rate (the higher the rate of change in the opening of the intake throttle valve 15, the higher the value) and the alcohol concentration AL in the fuel detected by the alcohol sensor 39.
Set according to C.

Table 1 shows the case of 100% gasoline and alcohol concentration A.
Since it is set only when LC is 85%, when the alcohol concentration ALC is other than the above, the additional fuel injection amount TTI is changed to the regular fuel injection amount Ti by proportional calculation.
Find out what percentage of the value should be set.

After setting the additional fuel injection amount TT1 in this way, in the next step 3, it is determined whether or not the acceleration determination in step 1 is the first time.

If the acceleration determination is the first time, the process proceeds to step 4, where it is determined whether there is a cylinder in which regular injection synchronized with engine rotation (fuel injection that allows desired air-fuel ratio control during steady operation) is being performed. If there is no cylinder in which regular injection is being performed, that is, if it is between regular injections, the process proceeds to step 5 and the additional injection amount T is determined for the cylinder that most recently completed regular injection. ? A large interrupt injection is performed.

The fuel injection amount Ti in regular injection is calculated at predetermined minute intervals and set in the output register each time, and is set in the output register when the regular injection timing synchronized with the engine rotation is reached. Since the fuel injection amount Ti is read out and the drive pulse signal corresponding to the fuel injection amount Ti is output to the fuel injection valve 26, in step 5, the normal value set in the output register is read out. The fuel injection amount Ti for injection is read out, and a drive pulse signal corresponding to a certain percentage of the additional fuel injection amount TT* is immediately output regardless of the regular injection timing.

On the other hand, if it is determined in step 2 that the acceleration operation determination is not the first time, or if it is determined in step 3 that there is a cylinder in which regular injection is currently being performed, the process proceeds to step 6.

In step 6, additional fuel injection amount T? , and in order to perform fuel injection at the regular injection timing, an instruction is given to set Ti+T□ in the output register.

In this way, T i + T ? is added to the output register. If you set l, when the regular injection timing is reached, Ti + T□ will be read out and a predetermined amount will be added to the regular injection amount according to the acceleration and alcohol concentration ALC at that time. Fuel will be supplied by injection. However, the fuel injection of T I + T ta is not performed continuously beyond a certain number of times, which is unrelated to the alcohol concentration ALC.

In the next step 7, it is determined whether the alcohol concentration ALC detected by the alcohol sensor 39 has changed. When the current alcohol concentration ALC has changed from the previous alcohol concentration ALC, the process proceeds to the next step 8, and the additional fuel injection amount T't* set based on the previous alcohol concentration ALC is added. It is determined whether there is a cylinder in which injection is being performed at the regular injection timing.

That is, since the alcohol sensor 39 is installed in the fuel supply pipe 25 near the fuel injection valve 26, the alcohol concentration ALC currently detected by the alcohol sensor 39 is the alcohol concentration ALC in the fuel to be injected in the future.
It can be seen that they are almost equal. Therefore, the current alcohol concentration ALC and the additional fuel injection amount T? When the alcohol concentration ALC used for setting II is different, it means that the desired additional fuel injection is not performed. Therefore, if there is a cylinder in which additional injection control is being performed based on an old alcohol concentration ALC detection value, corrections are made to perform additional injection in accordance with the actual alcohol concentration ALC.

In step 8, alcohol concentration AL before last time (before change)
If it is determined that there is a cylinder that is subject to additional injection control based on C, the process proceeds to step 9. In step 9, step 8
The fuel injection amount in the cylinder determined in is changed to the fuel injection amount additionally controlled based on the latest alcohol concentration ALC (
Ti+T? R) is exceeded.

Then, when the fuel that needs to be added based on the latest alcohol concentration ALC has already been injected, that is, the additional fuel injection amount T't* required based on the latest alcohol concentration ALC is greater than that at the start of injection. decreases, and Ti at the start of injection
When supplying +TT and I by injection is too much,
After injecting Tt+Tt* based on the latest data, the injection is stopped midway (step 10) to avoid unnecessary additional injections.

On the other hand, the latest data (alcohol concentration ALC after change)
(If Ti + Tt* has not yet been injected, it is necessary to continue the injection, so proceed to step ll and determine how far it will take to obtain Ti + T□ based on the latest data.) , and instructs continuous injection based on this required injection amount.If the required additional fuel injection amount Ti increases due to a change in the alcohol concentration ALC, additional fuel injection is performed based on the instruction in step 11. The fuel injection amount T□ is increased to prevent the air-fuel ratio from becoming leaner during acceleration due to additional injection less than the required amount according to the current alcohol concentration ALC.

In this way, if the alcohol concentration ALC changes after starting the additional injection based on the additional fuel injection amount T'tt set based on the alcohol concentration ALC and the acceleration, the alcohol concentration ALC corresponding to the changed alcohol concentration ALC is As much as possible, injection is stopped midway or extended, so even if the alcohol concentration ALC in the fuel changes during acceleration, it is possible to obtain an additional fuel injection amount that matches the changed alcohol concentration ALC. This makes it possible to control the air-fuel ratio during acceleration to a desired state.

In this example, it is assumed that regular injection and additional injection are performed in a sequential manner, but even if the fuel injection is controlled by simultaneous injection or group injection, additional injection can be performed in the same way as in this example. Alcohol concentration ALC before the end
When a change in alcohol concentration A is detected, the alcohol concentration A after the change is detected.
It is clear that air-fuel ratio control during acceleration can be improved by correcting the additional injection amount to correspond to LC.

<Effects of the Invention> As explained above, according to the present invention, when the alcohol concentration in the fuel changes during additional injection control after setting the additional injection amount during engine acceleration operation, the additional fuel injection amount is changed to Since the settings are corrected in accordance with the alcohol concentration, even if the alcohol concentration in the fuel changes during acceleration, the desired additional fuel injection amount can be obtained and the air-fuel ratio during acceleration can be controlled to the desired value. There is.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of the present invention, FIG. 2 is a system schematic diagram showing an embodiment of the invention, and FIG. 3 is a flowchart showing control details in the above embodiment. 11... Intake pipe 15... Intake throttle valve 25.
...Fuel supply pipe 26...Fuel injection valve 38
...Opening sensor 39...Alcohol sensor 40
... Control unit patent applicant Fujio Sasashima, agent for Nissan Motor Co., Ltd., patent attorney

Claims (1)

[Scope of Claims] An alcohol sensor that detects the alcohol concentration in the fuel is provided, and the fuel injection amount for regular injection performed in synchronization with engine rotation is controlled according to the alcohol concentration in the fuel detected by the alcohol sensor. An electronically controlled fuel injection system for an alcohol internal combustion engine configured to perform the following steps: an acceleration detection means for detecting an acceleration operation state of the engine; and a normal injection when the acceleration detection means detects an acceleration operation state of the engine. additional injection control means for controlling the additional injection by setting the additional fuel injection amount in the additional injection performed separately based on the acceleration driving state and the alcohol concentration; and during the additional injection control after the additional injection amount is set by the additional injection control means. An alcohol internal combustion engine characterized in that an additional injection amount correction means is provided for correcting and setting the additional fuel injection amount in accordance with the changed alcohol concentration when the alcohol concentration detected by the alcohol sensor changes. Electronically controlled fuel injection device.