JPH06173806A - Internal combustion engine injector - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] The present invention relates to an injection device for an internal combustion engine that maintains a constant fuel pressure supplied to a fuel injection valve to stabilize the amount of fuel injection. The purpose is to increase the fuel pressure supplied to the injection valve. [Configuration] When the internal combustion engine is stopped, the open / closed state of the driver's seat door is monitored, and when the door is opened, the routine is started. The pressure P _F in the fuel path leading to the fuel injection valve is measured (step 101), and it is checked whether the pressure is maintained above a predetermined pressure P (step 102). If P _F is lower than P, the pressure needs to be increased and the fuel pump is activated (step 103). After operating the fuel pump for a predetermined time, if the internal combustion engine has started to start, the process is terminated as it is, and if the internal combustion engine is still stopped, the fuel pump is stopped (step 107).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection device for an internal combustion engine, and more particularly to an injection device for an internal combustion engine, which maintains a constant fuel pressure supplied to a fuel injection valve to stabilize the injection amount of fuel.

[0002]

2. Description of the Related Art In recent years, electronically controlled fuel injection devices have been widely used in vehicle-mounted internal combustion engines because of the demand for higher performance and higher functionality of automobiles. According to a general electronically controlled fuel injection device, the optimum fuel injection amount for each operating state is calculated based on the detection values of various sensors that represent the operating state of the internal combustion engine, and the calculated amount of fuel is The fuel is injected from the fuel injection valve into the intake passage of the internal combustion engine.

As a fuel injection valve, a structure in which a fuel injection port is provided with a needle valve having an electromagnetic solenoid or a piezoelectric element as a drive source is widely known. In such a fuel injection valve, a desired injection amount is realized by constantly supplying fuel of a predetermined pressure to the fuel supply port and opening the needle valve at a predetermined duty ratio according to the amount to be injected. .

However, in the fuel injection valve having such a structure, when the pressure of the fuel supplied to the fuel supply port fluctuates, the amount of fuel injected while the needle valve is open fluctuates, and a predetermined amount is injected. In some cases, the desired injection amount cannot be secured for the duty ratio. That is, in order to stabilize the accuracy of the fuel injection amount, it is necessary to stabilize the pressure of the fuel supplied to the fuel injection valve.

Therefore, generally, in an internal combustion engine having a fuel injection valve, a fuel pressure regulator is provided in a fuel passage which connects a fuel pump for pumping fuel from a fuel tank to generate fuel pressure and a fuel supply port of the fuel injection valve. And the fuel pressure supplied to the fuel injection valve is used as the set pressure of the fuel pressure regulator.

However, in the structure in which the fuel pressure supplied to the fuel injection valve is adjusted by the fuel pressure regulator in this way, when the fuel pressure supplied from the fuel pump falls below the set value of the fuel pressure regulator for some reason. As a result, the fuel supplied to the internal combustion engine is reduced. When the amount of injected fuel decreases, the air-fuel mixture supplied to the internal combustion engine becomes constantly lean, which not only impairs the operating stability of the vehicle, but also efficiently brings out the purification function of the catalyst installed in the exhaust system. Will not be possible and the exhaust emission will be worse.

In order to prevent such a problem, Japanese Patent Laying-Open No. 1-118158 provides a sensor for detecting the fuel pressure in the fuel passage so that when the pressure of the fuel supplied to the fuel injection valve drops, the sensor can be easily operated. Disclosed is a device capable of detecting the pressure drop. Therefore, in the internal combustion engine equipped with the device described in the above publication, when some trouble occurs in the fuel supply system, such as deterioration of the fuel pump or abnormality of the fuel regulator, the trouble can be immediately detected, and the driver It is possible to activate a fail-safe function such as an error display on the display or fuel increase correction.

[0008]

By the way, the fuel existing in the fuel passage communicating between the fuel pressure regulator and the fuel injection valve is in a state of being expanded by being heated by residual heat during the operation of the internal combustion engine. Therefore, when the fuel is cooled by stopping the engine, the pressure in the fuel path decreases due to the contraction of the volume, and it may not be possible to secure a sufficient pressure.

However, in the above conventional device, the fuel pressure in the fuel path is monitored only while the internal combustion engine is operating. Therefore, at the time of starting the internal combustion engine, even if the fuel pressure is significantly reduced, the pressure reduction cannot be detected.

Therefore, in the internal combustion engine equipped with the above-mentioned conventional device, it is possible to immediately detect the decrease in the fuel pressure during the steady operation and take measures, but at the time of starting, the measures are delayed. , It is not possible to secure an accurate fuel injection amount for a while after starting the start of the internal combustion engine,
There is a problem that it hinders the improvement of startability.

The present invention has been made in view of the above points, and when a predetermined event executed immediately before the start of the internal combustion engine is detected, it is presumed that the internal combustion engine is subsequently started. An object of the present invention is to provide an injection device for an internal combustion engine that can secure an accurate fuel injection amount even at the time of starting by increasing the fuel pressure supplied to the fuel injection valve in advance.

[0012]

FIG. 1 shows a principle diagram of an injection device for an internal combustion engine which solves the above problems.

In FIG. 1, reference numeral 10 indicates an internal combustion engine equipped with the injection device according to the present invention. 20 is a fuel injection valve,
Reference numeral 23 is a fuel pressure regulator, 24 is a fuel pump, and 25 is a fuel tank. The fuel pump 24 pumps up fuel from the fuel tank 25 and supplies the fuel to the fuel supply port 20 of the fuel injection valve 20.
The fuel is supplied into the fuel passage 22 that connects the b and the fuel pump 24. The fuel pressure regulator 23 is connected to the fuel path 22.
It prevents the pressure of the fuel inside from exceeding a predetermined value. The fuel injection valve 20 appropriately connects the fuel injection port 20a and the fuel supply port 14b to inject a desired amount of fuel into the intake passage 13 of the internal combustion engine 10.

Further, in FIG. 1, reference numeral 1 is a start predicting means, and reference numeral 2 is a fuel pressure increasing means. The injector of the internal combustion engine according to the present invention is characterized in that it includes the starting predicting means 1 and the fuel boosting means 2. Starting prediction means 1
Monitors a predetermined event that occurs before the internal combustion engine 10 is started, and when detecting the event, predicts that the internal combustion engine 10 will be subsequently started. The fuel pressure boosting means 2 boosts the fuel pressure in the fuel path 22 when the starting predicting means 1 predicts that the internal combustion engine 10 is started.

[0015]

In the above structure, when the internal combustion engine 10 is operating, the fuel pump 24 supplies a larger amount of fuel than the consumed fuel into the fuel passage 22. Therefore, the fuel passage 2
The pressure in 2 is always equal to the open set pressure of the fuel pressure regulator 23, and the fuel supply port 20a of the fuel injection valve 20 is supplied with the fuel pressure equal to the open set pressure of the fuel pressure regulator 23.

When the internal combustion engine 10 is stopped, the fuel injection valve 2
Fuel injection from 0 to the internal combustion engine 10 is stopped, and the fuel pump 24 also stops its operation. Therefore, when the fuel warmed by the residual heat is cooled during the operation of the internal combustion engine 10, the pressure in the fuel passage 22 decreases as the volume of the fuel contracts.

The start predicting means 1 predicts that the internal combustion engine 10 will be subsequently started if a predetermined event that is always executed before the internal combustion engine is started is detected while the internal combustion engine 10 is stopped. Therefore, when a predetermined event is performed, the pressure in the fuel passage 22 is immediately increased by the fuel pressure increasing means 2, and when the internal combustion engine 10 starts to start, the pressure equal to the set pressure of the fuel pressure regulator 23 is set. Is supplied to the fuel supply port 20a of the fuel injection valve 20.

[0018]

FIG. 2 is a general view showing the structure of an embodiment of an injection device for an internal combustion engine according to the present invention.

In FIG. 2, reference numeral 10 indicates an internal combustion engine equipped with the injection device of this embodiment. Also, reference numerals 11 and 12
Indicate an intake port and an exhaust port of the internal combustion engine 10, respectively. Each intake port 11 is connected via a corresponding intake passage 13 to a surge tank 14 that alleviates the pulsation of intake pressure generated in each intake stroke.

The surge tank 14 is the intake duct 1
5 and the air flow meter 16 are connected to the air cleaner 17. In addition, a throttle valve 18 that opens and closes in response to a driver's accelerator operation and adjusts the amount of intake air supplied to the internal combustion engine 10 is arranged in the intake duct 15.

On the other hand, the exhaust port 12 is connected to a catalyst (not shown) via an exhaust manifold 19. This catalyst has a function of purifying the exhaust gas discharged from the internal combustion engine 10, and exhibits the most efficient purification function when the air-fuel ratio of the exhaust gas is maintained near the stoichiometric air-fuel ratio.

A fuel injection valve 20 is provided in each intake passage 13 connected to the intake port 11.
The fuel injection valve 20 is provided to supply a predetermined amount of fuel into the intake passage 13 and accurately obtain a desired air-fuel ratio.

The amount of fuel to be injected by the fuel injection valve 20 into the intake passage 13 is controlled by the air flow meter 16 for generating an output voltage corresponding to the intake air amount, the opening degree of the throttle valve 18, and the internal combustion engine 10. An engine control computer (not shown) sequentially calculates an optimum injection amount for each operating state of the internal combustion engine based on the detected value of the water temperature sensor 21 that detects the temperature.

Therefore, in such a fuel injection valve 20,
It is required that fuel can be injected with high accuracy and that it has excellent responsiveness to changes in the fuel injection amount.
FIG. 3 is a front cross-sectional view showing the configuration of the fuel injection valve 20 used in this embodiment to satisfy such requirements.

In FIG. 3, reference numeral 30 indicates a housing of the fuel injection valve 20, and a fuel injection port 20a is provided at one end thereof. A fuel supply port 20b communicating with the side surface of the housing 30 communicates with the fuel injection port 20a. An external fuel supply source is connected to the fuel supply port 20b so that the fuel is always supplied.

Inside the housing 30, the fuel injection port 2
A needle valve 31 for closing or opening 0a is arranged. That is, the needle valve 31 is connected to the fuel injection port 2
When 0a is opened, the fuel supplied to the fuel supply port 20b is injected from the fuel injection port 20a and supplied into the intake passage 13 of the internal combustion engine 10.

A cylinder 32 is formed inside the housing 30. Inside the cylinder 32, there are housed a piston 33 which is integrally formed with the needle valve 31 and can slide in the cylinder 32, a piezoelectric element 34, caps 35 and 36 for holding the piezoelectric element 34 from above and below. Here, the upper cap 35 abuts the upper wall of the housing 30, and the lower cap 36 can slide in the cylinder 32.

Therefore, when the piezoelectric element 34 expands and contracts in response to the supply of voltage, the lower cap 36 slides in the cylinder 32 together with the expansion and contraction. The fuel injection valve 2
At 0, lead wires 37 and 38 for applying a voltage for driving the piezoelectric element 34 are provided.

By the way, a hydraulic chamber 39 is formed in the cylinder 32 between the piston 33 integrally provided with the needle valve 31 and the lower cap 36. Also,
A disc spring 40 for return is arranged below the piston 33.

Therefore, when the piezoelectric element 34 receives the charging voltage and expands, the piston 33 is pressed through the hydraulic oil in the lower cap 36 and the hydraulic chamber 39. Piston 33
When is pressed, the needle valve 31 closes the injection port 20a and the fuel supply is stopped. In addition, the piezoelectric element 34
However, when the charge is discharged and contracts, the disc spring 40 pushes back the piston 33 and the injection port 20a communicates with the fuel supply port 20b, so that the fuel is injected again.

Here, the piezoelectric element 34 is an element that expands and contracts accurately with respect to the applied voltage, and the lead wire 3
With the configuration in which a constant voltage is applied between 7 and 38, the opening of the fuel injection port 20a shows a constant opening with high repeatability. Therefore, if the pressure of the fuel supplied to the fuel supply port 20b is constant, duty control of the voltage applied between the lead wires 37 and 38 is performed to control the fuel injection amount per unit time with high accuracy. Can be set arbitrarily.

However, even if the fuel injection valve 20 having the structure shown in FIG. 3 is used, when the pressure of the fuel supplied to the fuel supply port 20b changes, the fuel injection amount changes every time the fuel injection valve 20 is opened. It is unavoidable that a large error occurs in the fuel injection amount per unit time as a result.

Such an error in the fuel injection amount disturbs the air-fuel ratio of the air-fuel mixture supplied to the internal combustion engine 10, and
Not only does it impair the maneuverability of vehicles equipped with 0,
This lowers the purification function of the catalyst provided in the exhaust system, and causes a significant deterioration of exhaust emission.

Therefore, in the present embodiment, as shown in FIG. 2, a fuel regulator 23 is provided in the middle of a fuel path 22 communicating with the fuel supply port 20b of the fuel injection valve 20, and the fuel is supplied to the fuel injection valve 20. We are trying to stabilize the fuel pressure. In FIG. 2, reference numeral 24 denotes a fuel pump, which supplies the fuel pumped from the fuel tank 25 into the fuel path 22. Further, reference numeral 26 denotes a fuel filter, which is provided for the purpose of preventing foreign matter from entering the fuel injection valve 20.

The internal space of the fuel regulator 23 is divided by a diaphragm 23a into a fuel chamber 23b and a negative pressure chamber 23c. The fuel chamber 23b communicates with the fuel passage 22, and the pressure in the fuel chamber 23b is equal to the pressure in the fuel passage 22. In addition, in the fuel chamber 23b, the fuel tank 25
A fuel release passage 23d leading to is inserted. A valve body 23e integrally provided with the diaphragm 23a is located at the open end of the fuel release passage 23d. Further, the diaphragm 23a is biased in the direction of the fuel release passage 23d by a spring 23f provided in the negative pressure chamber 23c.

Therefore, when the internal pressure of the fuel chamber 23b, that is, the pressure in the fuel passage 22 is lower than a predetermined pressure, the valve 23e is caused to act by the action of the spring 23f.
The open end of 3d is closed, and the fuel chamber 23b and the fuel tank 25 are closed.
And are cut off.

On the other hand, when the pressure in the fuel passage 22 is higher than the predetermined pressure, the diaphragm 23a is replaced by the spring 23.
The valve body 2 is displaced in the negative pressure chamber 23c direction against the spring force of f.
Since the blockage of the fuel release passage 23d by 3e is released,
The fuel chamber 23b and the fuel tank 25 are electrically connected. As a result, a part of the fuel in the fuel chamber 23b and the fuel path 22 is returned to the fuel tank 25, and the pressure in the fuel path 22 decreases.

As described above, the fuel pressure regulator 23 has a function of preventing the pressure in the fuel passage 22 from exceeding a predetermined pressure. Further, the fuel pump 24 supplies a larger amount of fuel than the amount consumed in the fuel injection valve 20 to the fuel passage 22.
It is set to feed inside.

Therefore, as long as the fuel pump 24 is operating, the pressure in the fuel passage 22 does not become lower than the open set pressure of the fuel regulator 23, and the pressure of the fuel supplied to the fuel injection valve 20 is always the fuel. The pressure is maintained near the open set pressure of the regulator 23.

However, when the internal combustion engine 10 stops operating, the fuel pump 24 also stops accordingly, and the fuel path 2
No new fuel will be supplied to the inside of 2. When the temperature of the internal combustion engine decreases in this state, the temperature of the fuel heated by the residual heat during operation also decreases, and the fuel path 2
The pressure of the fuel present in 2 drops.

Therefore, when the internal combustion engine 10 is about to be restarted, the pressure in the fuel passage 22, that is, the pressure of the fuel supplied to the fuel injection valve 20, is higher than the opening set pressure of the fuel pressure regulator 23. May be significantly reduced. When the internal combustion engine 10 is started in such a state, a sufficient fuel injection amount cannot be obtained until the fuel pressure is recovered, so that the startability deteriorates and the operating state immediately after the start becomes unstable.

Therefore, in the present embodiment, the internal combustion engine 1
Paying attention to the fact that the vehicle door is always opened before 0 is started, it is predicted that the internal combustion engine 10 will be started subsequently when the door is opened, and before the internal combustion engine 10 is started. First, the fuel pump 24 is operated to increase the pressure in the fuel path 22.

In FIG. 2, reference numeral 50 indicates an electronic control unit for realizing such a function. In the figure, reference numeral 51 is a random access memory (RAM), 5
2 is a read only memory (ROM), 53 is a central processing unit (CPU), 54 is an output port, and 55 is an input port. These are connected to each other by a common bus 56,
Data is exchanged with each other.

The pressure sensor 27 provided in the fuel chamber 23b of the fuel pressure regulator 23 is connected to the input port 55 via the A / D converter 56, and the pressure in the fuel chamber 23b, that is, in the fuel passage 22 is connected. The signal corresponding to the pressure of is supplied. The input port 55 is further provided with an ignition switch (IG switch) 57 indicating start / stop of the internal combustion engine 10, a door switch 58 (combined with a room lamp switch) which is turned on / off in conjunction with opening / closing of a vehicle door,
A rotation speed sensor (NE sensor) 59 that emits a pulse signal corresponding to the rotation speed of the internal combustion engine 10 is connected, and signals representing respective states are supplied.

The output port 54 is connected to the fuel pump 24 via a drive circuit 60, and the door switch 58 described above is connected.
When it is determined that the fuel pump 24 needs to be operated based on a signal supplied from
A drive signal is supplied to activate the.

FIG. 4 shows a flow chart of a program executed by the electronic control unit 50 to realize the above functions. The operation of the electronic control unit 50 in this embodiment will be described below with reference to the same figure.

This routine is a routine executed for the purpose of pre-pressurizing the pressure in the fuel passage 22 before the internal combustion engine 10 is started, and the signal indicating "door open" is supplied from the door switch 58. It is started by This is because the driver always opens the vehicle door before the internal combustion engine 10 is started. The routine starting function corresponds to the starting predicting means 1 described above.

When the routine is started in this way,
First, at step 101, the pressure P _F in the fuel path 22 detected by the pressure sensor 27 is read. Next, the routine proceeds to step 102, where it is judged if the pressure P _F in the fuel path 22 is maintained at a predetermined pressure P or higher.

Here, when the pressure P _F in the fuel path 22 is equal to or higher than the predetermined pressure P (P _F ≧ P), no problem will occur even if the internal combustion engine 10 is started in that state, so that it remains as it is. The process ends. Then, in this case, similarly to the conventional device, the fuel pump 24 is operated in response to the IG switch 57 being turned on.

On the other hand, while the internal combustion engine 10 is stopped, the fuel path 2
When the pressure in 2 decreases and P _F <P, if the internal combustion engine 10 is started in this state, the fuel pressure supplied to the fuel injection valve 20 is insufficient, and for a while after the start. It is not possible to secure a sufficient fuel injection amount.

Therefore, in this embodiment, when the pressure P _F in the fuel passage 22 is lowered in this way, the routine proceeds to step 103 corresponding to the above fuel pressure boosting means 2,
The internal combustion engine 10 operates the fuel pump 24 even though it has not started yet.

Therefore, the pressure in the fuel passage 22 increases as the fuel pumped up by the fuel pump 24 is supplied, and finally reaches the open set pressure of the fuel pressure regulator 23. Then, until the internal combustion engine 10 is started thereafter, the fuel tank 2 is maintained while maintaining a predetermined fuel pressure.
5, the fuel circulates in the path that connects the fuel pump 24 and the fuel regulator 23.

By the way, the opening of the vehicle door does not necessarily mean that the internal combustion engine 10 is started immediately thereafter. This is because, for example, the door may be opened only to take out the luggage inside the vehicle. on the other hand,
It is sufficient to operate the fuel pump 24 for a predetermined time in order to raise the lowered pressure in the fuel path 22 to a predetermined pressure, and it is not necessary to continuously operate the fuel pump 24.

Therefore, when the fuel pump 24 is turned on in step 103, first, a predetermined time set as the time for sufficiently increasing the pressure in the fuel passage 22 is counted (step 104), and the inside of the fuel passage 22 is counted. Increase the pressure sufficiently. Subsequently, the output signal of the NE sensor 59 is read (step 105), and the rotation speed N of the internal combustion engine is read.
It is determined whether E is "0" (step 106),
If NE = 0, that is, if the internal combustion engine 10 is stopped, it is determined that it is not necessary to continue operating the fuel pump 24 any more, and the fuel pump 107 is turned off (step 10).
7).

As described above, for example, when the door is opened to take out the luggage inside the vehicle, the door should be opened again before the internal combustion engine 10 is started. If the pressure in the passage 22 has decreased, the fuel pressure is increased again by the above routine.

On the other hand, the driver is in the car,
If, for some reason, the predetermined time period in step 104 elapses before the internal combustion engine 10 is started, the fuel pump 24 is stopped before restarting, but the pressure in the fuel path 22 has already been sufficiently increased. There is no problem.

In step 106, NE ≠
When it is 0, that is, when the internal combustion engine 10 is in operation, it is necessary to pump up the consumed fuel from the fuel tank 25, and therefore the processing of this routine is ended while the fuel pump 24 is operating.

As described above, according to this embodiment, the internal combustion engine 1
The pressure in the fuel passage 22 at the time when 0 is started is surely raised to a predetermined level. Therefore, when the internal combustion engine 10 is started, a desired fuel injection amount is accurately realized, the startability of the internal combustion engine 10 is improved, and good maneuverability and exhaust emission are secured immediately after the start. In addition, the internal combustion engine 1
Even if 0 is not started, the fuel pump 24 does not continue to operate, so that the battery that is the vehicle-mounted power source is not overloaded.

In the above embodiment, the fuel pressure regulator 23 is provided with the pressure sensor 27, and when the door is opened while the internal combustion engine 10 is stopped, the pressure P _F in the fuel passage 22 is the predetermined pressure. The fuel pump 24 is operated only when it is less than P, but the structure is not limited to this. That is, without using the pressure sensor 27, the internal combustion engine 10
The fuel pump 24 may be operated for a predetermined period of time when the door is opened during the stop.

Further, the starting prediction of the internal combustion engine 10 is made by opening and closing the door of the vehicle. However, the invention is not limited to this, and it is possible to detect an event that is always performed before the internal combustion engine 10 is started. I wish I had it. Therefore, for example, a sensor may be provided in the driver's seat to detect that the driver is sitting in the driver's seat and predict the start.

[0061]

As described above, according to the present invention, the pressure in the fuel path is increased in advance before the internal combustion engine is started, and when the internal combustion engine is started, the fuel pressure of the predetermined pressure is always injected. Will be supplied to the valve. Therefore, unlike the conventional device, the fuel injection amount at the time of starting the internal combustion engine does not become unstable, and it is possible to secure good startability of the internal combustion engine and good steering stability of the vehicle immediately after the start. Have

[Brief description of drawings]

FIG. 1 is a principle diagram of an injection device for an internal combustion engine according to the present invention.

FIG. 2 is an overall diagram showing a configuration of an embodiment of an injection device for an internal combustion engine according to the present invention.

FIG. 3 is a front cross-sectional view showing the configuration of a fuel injection valve used in this embodiment.

FIG. 4 is a flowchart of a routine executed by the electronic control unit of this embodiment.

[Explanation of symbols]

 1 Start Prediction Means 2 Fuel Pressure Boosting Means 10 Internal Combustion Engine 20 Fuel Injection Valve 20a Fuel Injection Port 20b Fuel Supply Port 22 Fuel Path 23 Fuel Pressure Regulator 24 Fuel Pump 25 Fuel Tank 50 Electronic Control Device 58 Door Switch

Claims (1)

[Claims] 1. A fuel pressure is obtained by pumping fuel from a fuel injection valve and a fuel tank for injecting a desired amount of fuel into an intake passage of an internal combustion engine by appropriately controlling conduction between a fuel supply port and an injection port. A fuel pressure regulator for maintaining the fuel pressure in the fuel passage below a predetermined value in the fuel passage communicating with the fuel pump for generating the fuel pressure, and the fuel pressure supplied to the fuel supply port of the fuel injection valve. In a fuel injection system for an internal combustion engine, the starting prediction means for detecting a predetermined event occurring before starting the internal combustion engine and predicting the starting of the internal combustion engine based on the detected event, and the starting prediction means An injector for an internal combustion engine, comprising: a fuel pressure booster that boosts the fuel pressure in the fuel path when a start is predicted.