JPH09209877A - Fuel system for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve stating performance and exhaust gas performance when starting, by interposing a first solenoid valve between a fuel pump and an injector, interposing a second solenoid valve between the injector and a pressure regulator, and arranging a pressure sensor between the first and second solenoid valves. SOLUTION: A pressure sensor 10 is arranged between solenoid valves 9 interposed among a supply side fuel piping 7, a return side fuel piping 8 and an injector 2. Just after an internal combustion engine is stopped, an injector piping is disconnected from the fuel piping 8, fuel pressure is detected by the pressure sensor 10, and pressure and the present time are memorized. An amount leaked next from the injector 2 is estimated from difference between pressure detected by the pressure sensor 10 when a key switch is rotated up to the position of a starter switch and pressure detected just after an engine is stopped. The injection amount of the injector 2 just after starting is adjusted according to a concentration estimated in a control unit 6 by pressure difference and time difference in an intake manifold 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel supply system for an electronically controlled fuel injection type internal combustion engine.

[0002]

2. Description of the Related Art A conventional fuel supply device for improving startability is a fuel pressure reducing device for reducing or eliminating the fuel pressure applied to an injector when the internal combustion engine is stopped, as described in Japanese Patent Laid-Open No. 2-233868. By installing in the supply device,
Prevents fuel leakage and improves startability.

[0003]

In the above-mentioned prior art, a fuel pressure reducing device for reducing or eliminating the fuel pressure applied to the injector when the operation of the internal combustion engine is stopped is provided in the fuel supply device to prevent fuel leakage. In some cases, the fuel may leak due to the fact that minute impurities that could not be caught by the fuel filter are caught between the ball of the injector and the seat surface. An object of the present invention is to provide a fuel supply device that improves startability and exhaust gas performance during start-up.

[0004]

When the internal combustion engine is stopped, the solenoid valve is closed to disconnect the injector pipe from the fuel pipe, the fuel pressure in the injector pipe is measured immediately before starting, and control is performed by the pressure information and the internal combustion engine stop time. The above object is achieved by determining the injection amount of the injector in the unit.

When the internal combustion engine is stopped, the injector pipe is disconnected from the fuel pipe by means of a solenoid valve to measure the fuel pressure of the injector pipe which is interrupted immediately before starting.
By making the fuel injection amount appropriate, it is possible to realize the fuel supply device in which the mixing ratio of the fuel and the air at the time of starting is appropriate.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of claims 1 and 3 of the present invention will be described below with reference to the drawings. In FIG. 1, there is an internal combustion engine 1, and an injector (fuel injection valve) 2 for supplying fuel to the internal combustion engine 2, a pressure regulator for keeping a constant fuel pressure applied to the injector and returning a residual pressure fuel to a fuel tank 3, Fuel tank 3 to injector 2
A fuel pump 5 for pressure-feeding fuel to the control unit 5, a control unit 6 for controlling a control system including a fuel system, a fuel pipe 7 on the supply side,
Return side fuel pipe 8, supply side fuel pipe 7 and injector 2
1 and 2 between the injector 2 and the pressure regulator 4, and the control unit 6 controls the solenoid valve 9 and the pressure sensor 1 in exactly the same manner.
0, the intake manifold 11 which is a pipe for sending the intake air to the internal combustion engine constitutes the fuel supply device of the present embodiment. This fuel supply device is the same as the fuel supply device for an internal combustion engine using a normal injector except that the solenoid valve 9 and the pressure sensor 10 are provided.

During operation of the internal combustion engine, the two solenoid valves 9 are in communication with each other, the fuel pump 5 is operated by the control unit 6, and the fuel is pressure-fed from the fuel tank 3 to the injector 2 through the supply side fuel pipe 7. . Injector 2
The pressure of the fuel sent to is adjusted by the pressure regulator 4, and the amount of fuel calculated by the control unit 6 is injected from the injector 2 according to the operating conditions at that time. Then, the remaining fuel is returned to the fuel tank 3 through the pressure regulator 4 and the return side fuel pipe 8.

When the internal combustion engine is stopped and then restarted, the injector 2 is installed in the intake manifold 11 while the internal combustion engine is stopped.
Due to the more leaked fuel, the concentration of the fuel vapor is high, so that it becomes difficult to start the internal combustion engine at a normal injection amount. Therefore, the vapor concentration is estimated, and the fuel injection amount immediately after starting is adjusted.

First, immediately after the internal combustion engine is stopped, the fuel pump 5
Is stopped, the solenoid valve 9 is shut off, the injector pipe is shut off from the fuel pipe, the fuel pressure is measured by the pressure sensor 10, and the pressure and the current time are stored in the control unit.

Then, when the key switch is turned to the position of the starter switch next time, the fuel pressure is measured by the pressure sensor 10, and the pressure and the present time are stored in the control unit. If the fuel leaks from the injector 2 while the internal combustion engine is stopped, this pressure is somewhat lower than the pressure measured immediately after the internal combustion engine is stopped. The pressure drop at this time is due to the leakage from the injector 2 because the portion where the fuel leaks in the solenoid valve 9 is limited. The amount of leakage from the solenoid valve 9 is small enough to be ignored with respect to the amount of leakage from the injector 2.

Here, the amount of leakage from the injector 2 can be estimated from the difference between the pressure measured immediately after the internal combustion engine is stopped and the pressure measured this time. Further, the leaked fuel is vaporized in the intake manifold 11 and gradually leaks from the gap of the throttle valve. Therefore, since the amount of leakage increases as time elapses from when the internal combustion engine was stopped last time, it is necessary to take the difference between the time measured last time and the time measured this time into consideration. In this way, the concentration in the intake manifold 11 is controlled by the control unit 6 due to the pressure difference and the time difference.
Estimate by Then, the injection amount of the injector 2 immediately after starting is adjusted according to the estimated concentration. After that, the electromagnetic valve 9 is opened, the fuel pump 5 is rotated, and then the starter is rotated to start the internal combustion engine.

Next, the second and third embodiments of the present invention relate to in-cylinder injection of fuel.
1 is different from FIG. 1 in that the injector 2 has a structure in which fuel is directly injected into the internal combustion engine 1, and in comparison with FIG. 1 in which fuel is injected into the intake manifold,
Since the fuel pressure in the injector is high, the fuel pump and the pressure regulator have two stages, a low pressure side and a high pressure side. The roles of the fuel pump and the pressure regulator in FIG. 1 are played by the high-pressure side fuel pump 5 and the high-pressure side pressure regulator 4 in FIG. 2, respectively. The low-pressure side fuel pump 5 and the low-pressure side pressure regulator 4 play an auxiliary role of sending fuel of a constant pressure to the high-pressure side fuel pump 5. Other points are the same as those of the first and third embodiments of the present invention.

[0013]

EFFECTS OF THE INVENTION By supplying a proper fuel injection amount at the time of starting the internal combustion engine, the startability is improved and the exhaust gas performance of the internal combustion engine at the time of starting is improved.

[Brief description of drawings]

FIG. 1 is a functional block diagram showing a configuration of a first invention.

FIG. 2 is a functional block diagram showing the configuration of the second invention.

FIG. 3 is a flowchart showing control of the fuel supply device after the internal combustion engine of the invention is stopped.

FIG. 4 is a flowchart showing the control of the fuel supply device at the time of starting the internal combustion engine of the invention.

[Explanation of symbols]

1 ... Internal combustion engine, 2 ... Injector, 3 ... Fuel tank, 4
... Pressure regulator, 5 ... Fuel pump, 6 ... Control unit, 7 ... Supply side fuel piping, 8 ... Return side fuel piping, 9 ... Solenoid valve, 10 ... Pressure sensor, 11 ... Intake manifold.

Claims (3)

[Claims] 1. A fuel tank, an injector for injecting fuel into an intake manifold, a fuel pump for supplying fuel from the fuel tank to the injector, and a passage for returning fuel from the injector to the fuel tank. A fuel supply device for an internal combustion engine, comprising: a pressure regulator provided; a first electromagnetic valve provided between the fuel pump and the injector; and a second solenoid valve provided between the injector and the pressure regulator. And a pressure sensor provided between the first electromagnetic valve and the second electromagnetic valve. 2. A low-pressure side fuel pump for supplying fuel from a fuel tank to a high-pressure side fuel pump, and a low-pressure side pressure regulator provided in a passage for returning fuel from the high-pressure side fuel pump to the fuel tank, The high-pressure side fuel pump includes an internal-combustion engine including a high-pressure side pressure regulator that supplies fuel to an injector that directly injects fuel into the internal-combustion engine and returns the fuel from the injector to a fuel pipe that connects the low-pressure side fuel pump and the high-pressure side fuel pump. In the fuel supply device, the first electromagnetic valve provided between the high-pressure side fuel pump and the injector, the second electromagnetic valve provided between the injector and the high-pressure side pressure regulator, and the first electromagnetic valve Internal combustion characterized by having a pressure sensor provided between one electromagnetic valve and the second electromagnetic valve Fuel supply system of the function. 3. The fuel concentration at the time of starting according to claim 1 or 2, wherein the fuel concentration is estimated from the pressure from a pressure sensor for detecting the pressure applied to the injector and the time elapsed since the internal combustion engine was last stopped. A fuel supply device for an internal combustion engine having a means for determining