JP2858284B2 - Fuel supply control device for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel supply control device for an internal combustion engine, and more particularly to a fuel supply control device for controlling a fuel supply pressure to a fuel injection valve by a pressure regulator and controlling a fuel supply through a valve opening control time of the fuel injection valve. It relates to a device for controlling the quantity.

[0002]

2. Description of the Related Art Conventionally, in an electronically controlled fuel injection device for an internal combustion engine, the amount of fuel supplied to the engine is controlled by the valve opening control time of a fuel injection valve. In such a fuel supply device, if the pressure difference between the supply pressure of the fuel to the fuel injection valve and the intake pressure near the injection hole of the fuel injection valve is not constant, the constant fuel corresponding to the valve opening time of the injection valve is generated. It cannot be supplied. Therefore, the suction negative pressure on the downstream side of the throttle valve is led to the reference pressure chamber of the pressure regulator for adjusting the fuel supply pressure to the fuel injection valve, and the pressure difference between the pressure in the reference pressure chamber and the supply pressure from the fuel pump. That is, when the pressure difference between the intake pressure and the fuel pressure at the injection hole portion exceeds a predetermined value, a return passage for returning fuel to the fuel tank is opened, and the pressure difference is kept constant (Japanese Patent Application Laid-Open No. 60-1985). -212634, etc.).

[0003]

However, there is a case where it is necessary to arrange the pressure regulator at a position distant from the intake pipe of the engine due to the arrangement requirement of the pressure regulator. In this case, the pressure regulator and the throttle valve downstream are required. It was inevitable that the pressure introduction pipe connecting to the intake pipe would become long.

As described above, the configuration in which the suction negative pressure is guided to the pressure regulator through the long introduction path, the pressure in the reference pressure chamber of the pressure regulator responds to the change in the intake pressure near the injection hole of the fuel injection valve. There is a delay in the change. For this reason, when the intake negative pressure changes, the pressure difference between the injection port pressure and the fuel supply pressure deviates from an expected value, and an error may occur in the fuel supply control.

[0005] The present invention has been made in view of the above problems, and even if the pressure regulator is disposed at a position distant from the intake pipe of the engine, the intake air near the injection hole of the fuel injection valve is provided. An object of the present invention is to provide a fuel supply control device that can maintain the accuracy of fuel injection control with respect to pressure changes.

[0006]

Therefore, a fuel supply control device for an internal combustion engine according to the present invention is configured as shown in FIG . In FIG. 1, the pressure regulator is configured to determine the pressure difference between the pressure of the fuel pumped from the fuel tank by the fuel pump and the intake pressure at the injection hole of the fuel injection valve guided to the reference pressure chamber via the pressure introduction pipe. When the pressure is equal to or more than a predetermined value, a return passage for returning fuel to the fuel tank is opened to adjust the differential pressure to a constant value.

[0007] The fuel injection control means controls the valve opening control time of the fuel injection valve in accordance with engine operating conditions. Here, the injection port pressure detection means detects a parameter corresponding to the intake pressure of the injection port of the fuel injection valve, and the fuel injection correction means detects a change in the intake pressure of the injection port of the fuel injection valve.
Pressure in the reference pressure chamber of the pressure regulator
In order to respond to the response delay of the force change, the change rate of the intake pressure of the injection hole portion is detected based on the parameter detected by the injection hole portion pressure detecting means, and the valve opening control time is determined based on the change ratio. you correction.

[0008]

According to this configuration, in the pressure regulator in which the intake pressure of the injection hole of the fuel injection valve is guided to the reference pressure chamber via the pressure introducing pipe, the differential pressure between the intake pressure of the injection hole and the fuel supply pressure is reduced. The pressure is adjusted to be constant, but if the pressure change in the reference pressure chamber of the pressure regulator is delayed with respect to the actual pressure change of the injection hole due to the length of the pressure introduction pipe, the differential pressure is fixed. Injection cannot be performed under the conditions described above. Therefore, a change rate of the intake pressure of the injection valve is obtained, a response delay of a pressure change in the reference pressure chamber of the pressure regulator is corrected from the change rate to a valve opening control time, and a deviation of the differential pressure is opened. Ru der compensates by the correction of the valve control times.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. In FIG. 2 showing a system configuration of one embodiment,
Air is drawn into the internal combustion engine 1 from the air cleaner 2 via the intake duct 3, the throttle chamber 4, the intake collector 5 and the intake manifold 6.

A fuel injection valve 7 is provided for each cylinder in a branch portion of the intake manifold 6. The fuel injection valve 7 is an electromagnetic fuel injection valve that is energized and opened by being energized by a solenoid, and is closed by being deenergized, and opens according to a pulse width of a drive pulse signal sent from a control unit 21 described later. The fuel that is controlled and adjusted to a predetermined pressure is injected and supplied to each branch of the intake manifold 6.

A fuel pump 9 is provided in the fuel tank 8, and the fuel sucked and pumped by the fuel pump 9 is supplied to the fuel tank 8 through two pressure regulators 10, 11 and a fuel filter 12. The fuel is distributed and supplied to each fuel injection valve 7 via a supply pipe 13. The pressure regulator 10 is disposed in the vicinity of the fuel tank 8, and its reference pressure chamber has a suction negative pressure of the engine 1 from the intake collector 5 through a pressure introducing pipe 14 (the intake pressure of the injection hole of the injection valve 7). Pressure, which is approximately equal to the pressure)
When the pressure difference between the pressure of the fuel sent from the fuel pump 9 and the pressure in the reference pressure chamber becomes equal to or higher than a predetermined value, the return passage 15 is opened and the fuel is returned to the fuel tank 8 so that the pressure difference becomes constant. Adjust the fuel supply pressure as described above. If the differential pressure is kept constant, the amount of fuel injected and supplied with respect to the valve opening time of the fuel injection valve 7 has a linear characteristic, so that the injection amount can be controlled as the valve opening time.

The fuel that has passed through the pressure regulator 10 is filtered by a fuel filter 12 and then supplied to a pressure regulator 11 disposed relatively close to the engine 1, again through a pressure introducing pipe 14. By opening and closing the return passage 15 in accordance with the differential pressure between the suction negative pressure of the engine 1 introduced and the fuel supply pressure, the fuel pressure is adjusted to make the differential pressure constant.

However, in the present embodiment, the fuel supply pressure adjusted by the downstream pressure regulator 11 is set to be higher than the fuel supply pressure adjusted by the upstream pressure regulator 10. Under the condition in which the pressure adjustment by the regulator 10 is performed, the pressure adjustment operation by the downstream pressure regulator 11 is not performed, and
There is almost no return fuel from the pressure regulator 11.

With this configuration, the fuel heated by the heat of the engine 1 is prevented from returning to the fuel tank 8 as return fuel from the pressure regulator 11, and the upstream pressure regulator 10 sends the fuel to the vicinity of the engine 1. Since the fuel before being returned is returned to the tank as a result of the pressure adjustment, it is possible to avoid an increase in the temperature in the fuel tank due to the return fuel.

On the other hand, the upstream pressure regulator 10
An electromagnetic on-off valve 16 is interposed in the return passage 15. The control unit 21 closes the solenoid on-off valve 16 when the cooling water temperature is started at a predetermined temperature or higher, that is, when the engine 1 is restarted before it cools down, so that the upstream pressure regulator 10 The pressure regulation function is stopped, and pressure regulation by the downstream pressure regulator 11 is performed. At the time of the restart, the fuel temperature in the fuel pipe near the fuel injection valve 7 is high, and a large amount of vapor may be generated. However, as described above, the fuel is regulated by the pressure regulation operation from the fuel pipe on the upstream side. Is returned into the fuel tank 8, the circulation of fuel in the fuel pipe portion is promoted,
The vapor can be discharged into the fuel tank.

Further, each combustion chamber of the engine 1 is provided with an ignition plug 17 which ignites a spark to ignite and burn an air-fuel mixture. The control unit 21 includes a CPU, RO
A microcomputer including an M, RAM, an A / D converter, and an input / output interface, receiving input signals from various sensors, and receiving pulses of the driving pulse signal based on the input signals as described later. The pulse width i is calculated by calculating the width Ti (the valve opening control time of the fuel injection valve 7).
By outputting the drive pulse signal to the fuel injection valve 7 at a predetermined timing, the fuel supply to the engine 1 is electronically controlled.

The various sensors include an intake duct 3
Air flow meter 18 that measures the volume flow of intake air inside
And outputs a signal corresponding to the intake air flow rate Q of the engine 1. A crank angle sensor 19 is provided on the crankshaft or on a shaft (for example, a camshaft) that rotates in synchronization with the crankshaft.
And outputs a reference angle signal REF for each reference crank angle position and a unit angle signal POS for each unit crank angle (every 1 ° CA). Here, the engine rotation speed Ne can be calculated by measuring the cycle of the reference angle signal REF or the number of occurrences of the unit angle signal POS within a predetermined time.

Further, a water temperature sensor 20 for detecting a cooling water temperature Tw of the water jacket of the engine 1 is provided.
Here, the control unit 21 has an intake air flow rate Q
The basic injection pulse width Tp is calculated based on the intake air amount per intake stroke obtained based on the engine speed Ne and the engine rotation speed Ne, and various correction coefficients COEF are calculated based on the engine operation state such as the cooling water temperature Tw. The basic injection pulse width Tp is corrected by the various correction coefficients COEF to calculate the effective injection pulse width Te. Further, a voltage correction Ts for correcting a change in the effective valve opening time of the fuel injection valve 7 due to a change in the power supply voltage is set according to the power supply voltage, and the voltage correction Ts is added to the effective injection pulse width Te. To set the final injection pulse width Ti.

Then, a drive pulse signal having the injection pulse width Ti is output to the fuel injection valve 7 at a predetermined timing, and the fuel corresponding to the effective injection pulse width Te is injected and supplied from the fuel injection valve 7 to obtain a predetermined air-fuel ratio. To form an air-fuel mixture.
By the way, since the upstream pressure regulator 10 is disposed near the fuel tank 8 as described above, the pressure introducing pipe 14 for introducing the suction negative pressure to the pressure regulator 10 becomes long. Therefore, when the electromagnetic on-off valve 16 is opened and the pressure is regulated by the upstream pressure regulator 10, the actual suction negative pressure (injection valve 7
Pressure inlet pipe at the injection hole of the
There is a delay in the change in the pressure guided to the reference pressure chamber of the pressure regulator 10 via 14. The pressure regulator 10 aims at making the pressure difference between the intake pressure of the injection hole portion of the injection valve 7 and the fuel supply pressure constant, but due to the delay, the pressure difference from the desired value in the pressure regulator 10 As a result, an error occurs in the relationship between the injection amount and the valve opening time of the injection valve 7 (see FIG. 3 ).

Therefore, in the present embodiment, as shown in the flowchart of FIG. 4 , the response delay is corrected for the injection pulse width Ti, so that the desired value can be obtained even in the transient operation in which the suction negative pressure changes. The fuel amount can be injected and supplied. In the present embodiment, the fuel injection control means, the function of the fuel injection correction means, the control unit 21 is provided with the software as shown in the flowchart of FIG. 4, The intake of the nozzle hole portion of the injection valve In the present embodiment, the basic injection pulse width Tp is used as a parameter corresponding to the pressure, so that the air flow meter 18 and the crank angle sensor 19 correspond to the injection hole portion pressure detecting means.

In the flowchart of FIG. 4, first, in step 1, the basic injection pulse width Tp and various correction coefficients C
The effective injection pulse width Te (← Tp × C
OEF) is calculated. In the next step 2, the basic injection pulse width Tp corresponding to the suction negative pressure of the engine, that is, the injection port pressure of the injection valve 7 is weighted and averaged, and the result is taken as the intake pressure of the injection port of the injection valve 7 (hereinafter referred to as the intake pressure). , Simply referred to as the nozzle hole pressure).

Pm ← (a · Tp + b · Tp ₋₁ ) / (a + b) In step 3, the injection port pressure Pm calculated this time in step 2 and the previous calculated value Pm ₋₁ are calculated as the difference. The change rate ΔPm (← Pm−Pm ₋₁ ) of the hole pressure is obtained.
Here, when ΔPm is positive, the injection port pressure P
m indicates an increasing change (a negative pressure decreasing change). Therefore, in the pressure regulator 10, although it is necessary to increase the fuel supply pressure to the injection valve 7 by reducing the return flow rate, the increase in the fuel supply pressure is delayed due to the delay in the introduction of the negative pressure. On the other hand, when ΔPm is minus, it is the time when the injection hole pressure decreases.
Due to the delay in the introduction of the negative pressure, a decrease in the fuel supply pressure is delayed.

Therefore, when ΔPm is positive,
With the normal pulse width, the actual injection amount is smaller than the desired injection amount, and when ΔPm is negative, the actual injection amount is larger than the desired injection amount with the normal pulse width. turn into. Therefore, in the next step 4, a correction coefficient KTe for correcting the effective pulse width Te is set to a value exceeding 1.0 when the change rate ΔPm is positive, and 1.0 when the change rate ΔPm is negative. The value is set to a value less than the value so that the excess or deficiency of the injection amount due to the error of the fuel supply pressure can be corrected.

When the correction coefficient KTe is set based on the change rate ΔPm as described above, in the next step 5,
The effective injection pulse width Te is corrected by multiplying by the correction coefficient KTe, and a voltage correction amount Ts is added to the correction result to obtain a final injection pulse width Ti. With this correction, even if the introduction of the suction negative pressure to the pressure regulator 10 is delayed, the desired fuel can be injected and supplied.

In the above-described embodiment, the injection hole pressure is
Instead of estimating based on the basic injection pulse width Tp, a sensor for detecting the suction negative pressure may be provided, and the suction negative pressure detected by the sensor may be used as the injection port pressure. In the above embodiment, the system including the two pressure regulators 10 and 11 has been described. However, a system including only one pressure regulator may be a pressure regulator that introduces a suction negative pressure, and It is apparent that similar effects can be obtained by applying the above-described correction control similarly when the negative pressure introduction path is long.

[0026]

As described above, according to the present invention, in a system provided with a pressure regulator for introducing a suction negative pressure into a reference pressure chamber and making a differential pressure between an injection hole pressure and a fuel supply pressure constant, Even if a response delay occurs in the pressure change in the reference pressure chamber, the error in the differential pressure adjustment due to the response delay can be compensated for by correcting the valve opening control time of the fuel injection valve. There is an effect that the accuracy of fuel control can be maintained.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of the present invention.

FIG. 2 is a diagram showing a system configuration according to an embodiment of the present invention.

FIG. 3 shows response delay characteristics of a pressure regulator .
Time chart.

FIG. 4 is a flowchart showing injection correction control in the embodiment.
To

[Explanation of symbols]

Reference Signs List 1 engine 6 intake collector 7 fuel injection valve 8 fuel tank 9 fuel pump 10, 11 pressure regulator 12 fuel filter 13 fuel supply pipe 14 pressure introduction pipe 15 return passage 16 solenoid on-off valve 18 air flow meter 19 crank angle sensor 20 water temperature sensor 21 control unit

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) F02D 41/00-41/40 F02M 69/00

Claims (1)

(57) [Claims] 1. A pressure difference between a pressure of fuel pumped from a fuel tank by a fuel pump and an intake pressure of an injection hole portion of the fuel injection valve guided to a reference pressure chamber via a pressure introduction pipe is equal to or more than a predetermined value. A pressure regulator that opens a return passage for returning fuel to the fuel tank to adjust the differential pressure to a constant value; and a fuel injection control unit that controls a valve opening control time of the fuel injection valve according to engine operating conditions. An injection hole pressure detecting means for detecting a parameter corresponding to an intake pressure of an injection hole portion of the fuel injection valve; and
Response of pressure change in the reference pressure chamber of the pressure regulator
A fuel for detecting a change rate of the intake pressure of the injection hole based on a parameter detected by the injection hole pressure detecting means and correcting the valve opening control time based on the change ratio in response to the response delay. A fuel supply control device for an internal combustion engine, comprising: an injection correction unit.