JPH08121281A - Fuel injection device - Google Patents

Abstract

PURPOSE: To provide a fuel injection device in which fuel injection to an internal combustion engine can be quickly started at the start of the internal combustion engine. CONSTITUTION: A fuel injection device is constructed of an injector 2 arranged in an engine 1, an injection controlling solenoid valve 3, a common rail 4, a high pressure supply pump 7, a fuel tank 8, a low pressure supply pump 9, and an ECU 11. When a fuel pressure Pc inside the common rail 4 is not more than the predetermine pressure P1 (Pc>=P1) after the ECU 11 determines a stop of the engine 1, an ignition switch is turned on, so that the ECU 11 determines that an operator intends to operate the engine 1 again. Subsequently, the low pressure supply pump 9 is operated until a starter switch is turned on, and pressurized fuel is forcibly fed to the common rail 4. Then, a quantity of the pressurized fuel forcibly fed to the common rail 4 by means of the high pressure supply pump 7, which is operated when the starter switch is turned on, is reduced, so that a time required for bringing a fuel pressure inside the common rail 4 to the minimum injection pressure demanded by the engine 1 can be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a fuel injection device,
More specifically, the present invention relates to a fuel injection device including a pressure accumulating pipe.

[0002]

2. Description of the Related Art In a gasoline engine which is an internal combustion engine, from the viewpoint of measures against exhaust gas and improvement of fuel consumption rate, a fuel injection system in which fuel is pressurized by a pump and then injected from a fuel injection valve to an intake manifold or an intake port is proposed. Proposed, various methods of further injecting fuel directly into the combustion chamber have been proposed.

According to such a direct injection method, it is necessary to control the injection amount and injection timing of fuel according to the operating state of the internal combustion engine. As a control means, a solenoid valve is generally provided in the fuel injection valve, A method of opening and closing the nozzle by intermittently energizing this solenoid valve is adopted. However, since this control means controls the energization of the solenoid valve according to the time, there is a problem that the injection condition varies depending on the fuel supply pressure to the fuel injection valve.

Therefore, in the fuel injection control device for an internal combustion engine disclosed in Japanese Patent Laid-Open No. 62-645, a common fuel pressure accumulating pipe is provided in the fuel supply pipe connecting the fuel supply pump and the fuel injection valve. A configuration has been proposed in which the fuel pressure is adjusted by a pressure accumulator pipe and is supplied to each fuel injection valve. However, according to the fuel injection control device for the internal combustion engine, the fuel is temporarily accumulated in the fuel pressure accumulating pipe and then pressure-fed to the fuel injection valve. It is impossible to inject fuel from the fuel injection valve until the fuel is sucked from the fuel reservoir tank and sent to the fuel pressure accumulator pipe to reach a predetermined pressure. Therefore, there is a problem that the engine starting characteristic deteriorates immediately after the start of the engine until the fuel in the fuel accumulator reaches a predetermined pressure.

In order to solve this problem, the actual fairness 3-41
In the pressure-accumulation type fuel in-cylinder direct injection device disclosed in Japanese Patent No. 089, the fuel path between the fuel pump, the pressure accumulator, and the fuel injection valve is not fixed, and the engine is started and when the engine is not started. The fuel passage is switchable. As a result, when the engine is started, the fuel is directly pumped from the fuel pump to the fuel injection valve without passing through the pressure accumulator, and the volume of the high-pressure fuel pipe is reduced to improve the fuel pressure-up property.

Further, in the engine fuel pressure control method disclosed in JP-A-4-339143, the engine is restarted by keeping the fuel pressure in the pipe of the fuel supply passage at a high pressure when the engine is stopped. It improves the sex.

[0007]

However, according to the pressure-accumulation type fuel in-cylinder direct injection device disclosed in Japanese Utility Model Publication No. 3-41089, it is necessary to add a three-way switching valve and a bypass passage. There is a problem that the configuration becomes complicated and it is difficult to mount the vehicle. In addition, JP-A-4-3
According to the engine fuel pressure control method disclosed in Japanese Patent No. 39143, the fuel pressure in the pipe is maintained at a high pressure even when the engine is stopped in order to improve the restartability of the engine. Therefore, a high pressure is applied to the fuel injection valve. There is a problem in that the time becomes long and oil tightness occurs in the nozzle seat portion in the fuel injection valve, and fuel may flow out into the engine combustion chamber, which adversely affects exhaust gas components when the engine is restarted.

The present invention has been made to solve such a problem, and an object of the present invention is to provide a fuel injection device for promptly starting fuel injection into an internal combustion engine when starting the internal combustion engine. .

[0009]

According to the invention for solving the above-mentioned problems, the fuel injection device according to claim 1 accumulates the fuel supplied from the high-pressure pump in the accumulator pipe, and through this accumulator pipe. A fuel injection device for injecting fuel into each cylinder from a fuel injection valve provided in each cylinder of the internal combustion engine, the low-pressure pump supplying fuel to the high-pressure pump, and the operation start time of the internal combustion engine The operation start notifying means for giving advance notice, the control means for starting the driving of the low pressure pump and controlling the fuel discharge of the low pressure pump before the operation start time given by the operation start notifying means, and the fuel pressure in the accumulator pipe are And a communication passage for allowing the fuel discharged from the low-pressure pump to flow into the accumulator pipe when the discharge pressure is lower than the discharge pressure of the low-pressure pump.

A fuel injection device according to a second aspect of the present invention is the fuel injection device according to the first aspect, wherein the operation start notifying means is an ignition switch. The fuel injection device according to claim 3 of the present invention is the fuel injection device according to claim 1 or 2, wherein the control means controls the discharge pressure of the high-pressure pump from the low-pressure pump to a predetermined pressure or more. The discharge pressure to the high-pressure pump is controlled.

According to a fourth aspect of the present invention, there is provided a fuel injection system according to the third aspect, wherein the predetermined pressure is a pressure value necessary for operating the internal combustion engine. . The fuel injection device according to claim 5 of the present invention is the fuel injection device according to claim 3, wherein
The predetermined pressure is a maximum discharge pressure of the low pressure pump.

According to a sixth aspect of the present invention, in the fuel injection system according to the third aspect, the control means sets the discharge pressure of the low pressure pump to the high pressure after the operation of the internal combustion engine is started. It is characterized in that control is performed to reduce the required pressure of the pump. A fuel injection device according to a seventh aspect of the present invention is the fuel injection device according to the third aspect, wherein the control means controls to increase the discharge pressure of the low-pressure pump to a required predetermined pressure of the high-pressure pump or more. The control is continued for a predetermined period or more, and after the lapse of the predetermined period, control is performed to reduce the discharge pressure of the low-pressure pump to the required predetermined pressure of the high-pressure pump.

A fuel injection device according to an eighth aspect of the present invention is the fuel injection device according to the third aspect, wherein the pressure accumulation pipe is provided with a pressure detection means for detecting the fuel pressure in the pressure accumulation pipe. When the fuel pressure in the pressure accumulating pipe reaches or exceeds a predetermined pressure, the discharge pressure of the low pressure pump is reduced to the required predetermined pressure of the high pressure pump.

A fuel injection device according to a ninth aspect of the present invention is the fuel injection device according to the first aspect, wherein the communication passage is a flow passage formed in the high pressure pump, the high pressure pump and the high pressure pump. It is characterized by comprising a pipe communicating with the pressure accumulating pipe and a check valve provided in the pipe.
A fuel injection device according to claim 10 of the present invention is
The fuel injection device according to claim 1, wherein the communication passage is
It is characterized by comprising a bypass pipe communicating the low pressure pump and the pressure accumulating pipe without passing through the high pressure pump, and a check valve provided in the bypass pipe.

A fuel injection system according to an eleventh aspect of the present invention is the fuel injection system according to the ninth or tenth aspect, wherein the opening pressure of the check valve is set to be equal to or lower than the discharge pressure of the low pressure pump. It is characterized by

[0016]

According to the fuel injection device of the present invention, when the fuel pressure in the pressure accumulating pipe is lower than the discharge pressure of the low pressure pump, the low pressure pump is started to be driven before the operation start time notified by the operation start notifying means. Since the fuel discharge of the low pressure pump is controlled by the control means, the fuel pressure in the pressure accumulation pipe can be increased by the low pressure pump before the start of the internal combustion engine. As a result, the amount of fuel pumped by the high-pressure pump can be reduced, so that the fuel pumping period by the high-pressure pump can be shortened, and at the start of internal combustion engine startup, the fuel injection valve can quickly start fuel injection into the internal combustion engine. There is.

Further, according to the fuel injection device of the present invention, when the fuel pressure in the pressure accumulating pipe is lower than the discharge pressure of the low pressure pump, the communication passage for allowing the fuel discharged from the low pressure pump to flow into the pressure accumulating pipe is the high pressure pump. Since it consists of a bypass pipe that connects the low-pressure pump and the pressure accumulator pipe without passing through the check valve and a check valve provided in the bypass pipe, a flow path that connects the low-pressure pump and the accumulator pipe to the high-pressure pump is provided. Since it is not necessary to provide it, the structure of the high-pressure pump can be simplified. This has the effect of reducing the cost of the high-pressure pump.

[0018]

Embodiments of the present invention will be described below with reference to the drawings. (First Embodiment) A fuel injection device according to a first embodiment of the present invention will be described with reference to FIGS. As shown in Figure 1,
The engine 1 is provided with, for example, four injectors 2 corresponding to four cylinders. Mainly, the injector 2, the injection control solenoid valve 3, the common rail 4, the high pressure supply pump 7, the fuel tank 8, the low pressure supply pump. A fuel injection device is composed of 9 and the electronic control unit 11.

The injection control solenoid valve 3 (hereinafter referred to as "electromagnetic valve") located upstream of the injector 2 is controlled by an electronic control unit 11 (hereinafter referred to as "ECU"), which will be described later, so that the valve is not shown. To control the supply of high-pressure fuel to the injector 2. Solenoid valve 3
Corresponds to the number of injectors 2. For example, in the case of the first embodiment, four solenoid valves 3 corresponding to the four injectors 2 are provided.

The common rail 4 is located upstream of the solenoid valve 3 and stores the high pressure fuel supplied to the plurality of injectors 2 via the branch passages. While the solenoid valve 3 is open, the high-pressure fuel accumulated in the common rail 4 is injected into each cylinder via each injector 2. A pressure sensor 14 that detects the fuel pressure in the common rail 4 is provided in the common rail 4.
The pressure detection signal detected in 1 is transmitted to the ECU 11.

The high-pressure supply pump 7, which is connected to the common rail 4 by the pipe 6a and the low-pressure supply pump 9 by the pipe 6b, pressurizes the fuel sucked from the fuel tank 8 through the low-pressure supply pump 9 to a high pressure. , Check valve 5
High-pressure fuel is pressure-fed to the common rail 4 via. The fuel pressure feed amount to the common rail 4 is adjusted by a metering solenoid valve 10 provided in the high pressure supply pump 7.

As shown in FIG. 2, the ECU 11 includes a CPU
11a, RAM 11b, ROM 11c, input / output unit 11
d, a bidirectional bus 11e. The input / output unit 11d includes an ignition switch sensor 12, a starter sensor 13, a pressure sensor 14, and a cam angle sensor 15.
Each sensor signal is input from the etc., CPU 11a, RAM
11b, ROM 11c, etc. The solenoid valve 3, the low pressure supply pump 9, the metering solenoid valve 10 and the like are controlled via the input / output unit 11d according to the result of this calculation.

For example, an engine speed sensor and a load sensor (not shown) detect the engine speed and load condition, and the optimum fuel injection timing and fuel injection amount according to the operating condition of the engine determined by these detection signals are used as EC.
U11 calculates. The ECU 11 controls the solenoid valve 3 based on the result of this calculation, and injects a predetermined amount of fuel from the injector 2 at a predetermined fuel injection timing. Further, the ECU 11 uses the pressure detection signal detected by the pressure sensor 14 of the common rail 4 so that the fuel pressure in the common rail 4 reaches an optimum value that is set in advance according to the engine speed and load. To control. Further ECU
An ignition switch signal from an ignition switch sensor 12 that gives an advance notice of the engine operation start time and a starter signal from a starter sensor 13 that determines the operation start are input to 11 and are used to control a high-pressure supply pump 7, which will be described later.

The high-pressure supply pump 7 is provided with a cam shaft (not shown), and the cam shaft is rotationally driven by receiving the rotational movement of a crank shaft (not shown) of the engine 1 via a belt (not shown).
The rotation ratio between the camshaft and the crankshaft is 1: 1 and the camshaft has an eccentric circular cam surface (not shown). A cam chamber (not shown) is formed on the lower end side of the pump housing 30 of the high-pressure supply pump 7, and the cam shaft having the above-mentioned cam surface is inserted into the cam chamber.

As shown in FIG. 3, the pump housing 30
A cylinder 31 is mounted therein, and a reciprocable plunger 32 is slidably accommodated in the cylinder 31. A pump chamber 33 is defined by the end surface of the plunger 32 and the inner wall of the cylinder 31. A low-pressure passage 36 is formed on the suction side of the cylinder 31, and the low-pressure passage 36 and the pump chamber 33 communicate with each other via the metering solenoid valve 10. A check valve 5 is provided on the discharge side of the cylinder 31.

The metering solenoid valve 10 comprises a solenoid 37, a valve element 38, a seat portion 39, an armature (not shown), and a spring. By energizing the solenoid 37, the armature is generated by the electromagnetic force generated in FIG.
It is sucked up and moves. Along with the movement of the armature, the valve element 38 formed at the end of the armature moves in the valve closing direction, and the valve element 38 is seated on the seat portion 39 to close the valve.
On the other hand, when the solenoid 37 is not energized, the spring urges the armature downward in FIG. 3, so that the valve element 38 moves in the valve opening direction and opens.

The check valve 5 comprises a valve body 34 and a return spring 35 for urging the valve body 34 in the valve closing direction. As shown in FIG. 3A, when the plunger 32 descends due to the rotation of the camshaft, the solenoid valve 10 is controlled by the ECU 11 to be in the non-energized state. As a result, the solenoid valve 10 is opened and the low pressure passage 36 communicates with the pump chamber 33, so that the low pressure fuel supplied from the low pressure supply pump 9 is transferred to the pump chamber 33.
Inhaled. This suction stroke fills the pump chamber 33 with low-pressure fuel.

As shown in FIG. 3 (b), when the plunger 32 rises due to the rotation of the camshaft, the solenoid valve 10 is controlled by the ECU 11 at a predetermined time to change from the non-energized state to the energized state. As a result, the solenoid valve 10 is closed and the low pressure passage 36 and the pump chamber 33 are shut off.
The low pressure fuel therein is pressurized. The fuel in the pump chamber 33 is pressurized by this pressurizing process.

As shown in FIG. 3C, when the plunger 32 further rises due to the rotation of the camshaft, the pressure of the fuel filling the pump chamber 33 increases. Due to this increase in fuel pressure, when the fuel pressure reaches the valve opening pressure of the check valve 5, the valve body 34 is pushed in the valve opening direction against the biasing force of the return spring 35, and the check valve 5 is opened. As a result, the pressurized high-pressure fuel is pressure-fed to the common rail 4, and the pressure-feeding process ends.

By repeating the suction stroke, the pressurization stroke and the pressure feeding stroke in this manner, the low pressure fuel supplied from the low pressure supply pump 9 is pressurized by the high pressure supply pump 7, and the high pressure fuel is supplied to the common rail 4. Further, the fuel supply amount to the common rail 4 can be changed by the energization time of the solenoid valve 10 controlled by the ECU 11. That is, the ECU 11 controls the energization state of the solenoid valve 10 based on the information obtained from the cam angle sensor 15 arranged on the crank shaft (not shown) of the engine 1 to determine the pressurization start time and supply the fuel to the common rail 4. The amount is changing.

The low-pressure supply pump 9 is an electric fuel supply pump, pressurizes the fuel sucked from the fuel tank 8 and sends it to the above-mentioned high-pressure supply pump 7 under pressure. Since the start and end of fuel supply of the low-pressure supply pump 9 are controlled by the drive signal from the ECU 11, the supply fuel flow rate and pressure can be controlled by the ECU 11. Next, the operation of the fuel injection device according to the first embodiment will be described with reference to FIGS.

The flowchart shown in FIG. 6 shows an interrupt routine, and this interrupt routine is executed by interruption every predetermined time after the power supply of the ECU 11 is turned on.
First, in step 51, the engine stop determination is made. This engine stop determination is determined by monitoring the input of the sensor signal from the cam angle sensor 15 shown in FIG. 2 arranged on the crank shaft (not shown) of the engine 1 and calculating the input interval of the sensor signal to determine the input interval. It depends on whether or not the time is reached. For example, when the input interval is 1 sec or more, it is considered that the engine 1 is not operating and it is determined that the engine is stopped.

If it is determined in step 51 that the engine is not stopped, the engine is operating, and the control is shifted to step 59. In step 59, since the low pressure fuel is supplied to the high pressure supply pump 7, Vnor is applied to the low pressure supply pump 9 as the driving voltage Vf of the low pressure supply pump 9. This Vnor corresponds to the minimum voltage required to fill the pressurized fuel of the low pressure supply pump 9 into the pump chamber 33 in the high pressure supply pump 7. As a result, the power consumption is reduced, and the interrupt routine is ended in the next step 60.

When it is judged in step 51 that the engine is stopped, the fuel pressure Pc in the common rail 4 is detected by the pressure sensor 14 in the next step 52, and the magnitude relationship between the detected fuel pressure Pc and the predetermined pressure P1 is compared. To do. By this comparison, it is determined whether or not the fuel discharge pressure of the low pressure supply pump 9 is the valve opening pressure of the check valve 5 in the high pressure supply pump 7. Here, the predetermined pressure P1 is set to a value somewhat higher than the maximum discharge pressure of the low pressure supply pump 9.

If it is determined in step 52 that the fuel pressure Pc and the predetermined pressure P1 are not Pc ≤ P1, the fuel does not flow into the common rail 4 even if the low pressure supply pump 9 is driven. Transition. In step 58, the drive voltage Vf applied to the low-pressure supply pump 9 is set to 0, that is, the applied voltage is cut off and the low-voltage supply pump 9 is
To stop driving.

When it is judged in step 52 that Pc ≤P1, that is, when the fuel pressure in the common rail 4 is judged to be sufficiently low, the ignition switch signal from the ignition switch sensor 12 is turned on in the next step 53. It is determined whether or not the driver has the intention to restart the engine operation. When it is determined in step 53 that the ignition switch signal is not on, the operation of the engine 1 is not started, and therefore, in step 58, the voltage applied to the low pressure supply pump 9 is cut off and the driving of the low pressure supply pump 9 is stopped.

When it is determined in step 53 that the ignition switch signal is ON, the driver has the intention to restart the engine operation, so that it is announced that the operation of the engine 1 will be started. Drive voltage Vf of low-pressure supply pump 9 to maximum drive voltage Vmax
And As a result, the pressurized fuel from the low pressure supply pump 9 is pumped into the common rail 4. Here, the maximum drive voltage Vmax is an applied voltage that controls the discharge pressure of the low-pressure supply pump 9 to the maximum pressure.

Next, at step 55, the starter signal of the starter sensor 13 is detected to judge whether or not the starter is operating. If it is determined in step 55 that the starter signal is on, the drive voltage Vf of the low-pressure supply pump 9 is set to the maximum drive voltage Vmax in step 54, which may cause an abnormal decrease in the battery voltage, and the engine 1 Since the fuel can be discharged from the high pressure supply pump 7 to the common rail 4 by the operation of, the control shifts to step 59. In step 59, the drive voltage Vf of the low pressure supply pump 9 is set to Vnor as described above. This reduces power consumption, and the next step 60
Ends the interrupt routine.

When it is determined in step 55 that the starter signal is not on, the maximum discharge pressure continuation counter C _VM of the low pressure supply pump 9 is incremented by 1 in the next step 56. In step 57, the maximum discharge pressure continuation counter C _VM counted up by 1 in step 56 is compared with a constant C _N corresponding to a predetermined maximum discharge pressure continuation time of the low pressure supply pump 9, for example, 2 sec. When the low pressure supply pump 9 is driven to the maximum discharge pressure while the fuel pressure in the common rail 4 is at the atmospheric pressure, the fuel pressure in the common rail 4 becomes the maximum discharge pressure of the low pressure supply pump 9 for the predetermined maximum discharge pressure duration. It's time to reach.

When it is determined in step 57 that C _VM ≧ C _N, it is determined that the fuel in the common rail 4 has been sufficiently precompressed, and the control is shifted to step 59. In step 59, the drive voltage Vf of the low pressure supply pump 9 is set to Vnor as described above, and the discharge pressure of the low pressure supply pump 9 is lowered. As a result, the power consumption is reduced, and the interrupt routine is ended in the next step 60.

When it is judged in step 57 that C _VM ≧ C _N is not satisfied, it is considered that the fuel in the common rail 4 is not sufficiently precompressed, and the state in which the maximum discharge pressure control is continued is maintained, and in the next step 60. Terminate the interrupt routine. The timing chart shown in FIG. 5 shows that when the low-pressure supply pump 9 is controlled in accordance with the above-mentioned flowchart,
Particularly, the behavior of the fuel pressure in the common rail 4 when the control is started from the state of Pc ≦ P1 (step 53) is shown. Here, the dotted line shown in FIG. 5 represents the rising characteristic of the fuel pressure in the common rail by the fuel injection device of the comparative example in which the control of the above-mentioned flow chart is not performed.

Since the low-pressure supply pump 9 is not driven from the time when the ECU 11 is turned on until the ignition switch is turned on, the fuel pressure in the common rail 4 becomes a constant pressure (atmospheric pressure). When the driver turns on the ignition switch, the ignition switch sensor 12 outputs an ignition switch signal to the ECU 1.
1 is transmitted, and it is determined in step 53 shown in FIG. 6 that the ignition switch signal is on. According to the determination in step 53, Vmax is applied to the low pressure supply pump 9 so that the discharge pressure of the low pressure supply pump 9 becomes the maximum discharge pressure in step 54 shown in FIG. Then, the fuel pressure in the pump chamber 33 increases due to the discharged fuel that is pressure-fed from the low pressure supply pump 9 to the high pressure supply pump 7, and at the time when it becomes equal to or higher than the valve opening pressure of the check valve 5, the check is performed as shown in FIG. The valve 5 opens. By opening the check valve 5, the fuel in the pump chamber 33 flows into the common rail 4, and the fuel pressure in the common rail 4 is gradually increased to the discharge pressure of the low pressure supply pump 9.
After a lapse of a predetermined time, the driving voltage of the low pressure supply pump 9 is Vnor
However, since the check valve 5 in the high-pressure supply pump 7 is closed to prevent the fuel from flowing out from the common rail 4 to the high-pressure supply pump 7, the fuel pressure in the common rail 4 does not decrease. Retained.

When the starter switch is turned on by the driver, the starter operates and the high pressure supply pump 7 is rotationally driven by the operation of the engine 1. This high-pressure supply pump 7
High-pressure fuel is pumped into the common rail 4 from the high-pressure supply pump 7 in synchronization with the reciprocating movement of the plunger 32 that is determined by the cam surface formed on the cam shaft (not shown) housed therein. By the high-pressure fuel pumping synchronized with the reciprocating movement of the plunger 32, the fuel pressure in the common rail 4 is further increased, and when the fuel pressure in the common rail 4 reaches the minimum injection pressure required by the engine 1, the fuel pressure to the engine 1 is increased. Fuel injection is started. As described above, the fuel pressure in the common rail 4 is increased more smoothly than before the engine is started, as compared with the case of the comparative example indicated by the dotted line in FIG. 5, so that the engine startability can be improved.

According to the first embodiment, after the ECU 11 judges that the engine has stopped, the fuel pressure Pc in the common rail 4 is reduced.
When the magnitude relationship between the pressure and the predetermined pressure P1 is Pc ≤ P1,
When the ignition switch is turned on, the ECU 11 determines that the driver has the intention of restarting the engine operation. Then, the low-pressure supply pump 9 is operated and the pressurized fuel is pressure-fed to the common rail 4 until the starter switch is turned on. Therefore, the amount of pressurized fuel that is pressure-fed to the common rail 4 by the high-pressure supply pump 7 that is activated when the starter switch is turned on is changed. Can be reduced. As a result, the time required for the fuel pressure in the common rail 4 to reach the minimum injection pressure required by the engine 1 is shortened, and the restartability of the engine 1 is improved.

(Second Embodiment) A fuel injection device according to a second embodiment of the present invention will be described with reference to FIG. The same components as those in the first embodiment are designated by the same reference numerals.
In the first embodiment described above, when the high pressure supply pump 7 is stopped, the pressurized fuel is pressure-fed from the low pressure supply pump 9 to the common rail 4 via the high pressure supply pump 7, but the fuel injection device of the second embodiment is used. Differs from the first embodiment in that a pipe 16 that bypasses the high pressure supply pump 7 and connects the low pressure supply pump 9 and the common rail 4 is provided.

As shown in FIG. 7, the pipe 6b from the low pressure supply pump 9 to the high pressure supply pump 7 is branched to bypass the high pressure supply pump 7 and communicate with the common rail 4.
Is provided. A check valve 17 for preventing fuel from flowing out from the common rail 4 to the low-pressure supply pump 9 is provided in the middle of the pipe 16, and the valve opening pressure is increased by the urging force of a spring (not shown) housed in the check valve 17. It is set.
The opening pressure of the check valve 17 is set to be equal to or lower than the discharge pressure of the low pressure supply pump 9. As a result, the same operation as in the first embodiment is performed by controlling the low pressure supply pump 9 used in the first embodiment.

According to the second embodiment, since the high pressure supply pump 7 is bypassed and the pipe 16 capable of directly pumping the pressurized fuel from the low pressure supply pump 9 to the common rail 4 is provided, the high pressure supply pump 7 has a low pressure supply pump. It is not necessary to provide a passage for communicating the common rail 9 with the common rail 4, and the structure of the high-pressure supply pump 7 can be simplified. This has the effect of reducing the cost of the high-pressure supply pump 7.

In the present embodiment, the discharge pressure of the low pressure supply pump 9 is switched according to the drive time under the control of steps 56 and 57 shown in FIG. 6, but the present invention is not limited to this, and the discharge pressure within the common rail may be changed. For example, the pressure sensor provided directly detects the fuel pressure in the common rail, and controls the drive voltage of the low-pressure supply pump by determining whether it is equal to or higher than a predetermined pressure (for example, the maximum discharge pressure of the low-pressure supply pump) to discharge the low-pressure supply pump The pressure may be switched. Thereby, the fuel pressure in the common rail can be controlled correspondingly, and there is an effect that more accurate control can be performed.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of a fuel injection device according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing a schematic configuration of an electronic control unit of the fuel injection device according to the first embodiment.

FIG. 3 is a schematic cross-sectional view of a pump chamber of a high pressure supply pump of the fuel injection device according to the first embodiment.

FIG. 4 is a schematic cross-sectional view showing a state when the engine of the pump chamber shown in FIG. 3 is stopped.

FIG. 5 is a timing chart showing the fuel pressure behavior of the fuel injection device according to the first embodiment when the engine is started.

FIG. 6 is a flowchart showing each control executed by the electronic control unit of the fuel injection device according to the first embodiment.

FIG. 7 is an overall configuration diagram of a fuel injection device according to a second embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 engine (internal combustion engine) 2 injector (fuel injection valve) 3 injection control solenoid valve 4 common rail (accumulation piping) 5, 17 check valve 6a, b piping (communicating passage, piping) 7 high pressure supply pump (high pressure pump) 8 Fuel tank 9 Low-pressure supply pump (low-pressure pump) 10 Metering solenoid valve 11 Electronic control unit (control means) 12 Ignition switch sensor (operation start notice means) 16 Piping (bypass piping) 33 Pump chamber (communicating passage,
Flow path) 36 low-pressure passage (communication passage,
Flow path)

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location F02M 55/02 350 P F02N 11/08 Y

Claims (11)

[Claims] 1. A fuel for accumulating fuel supplied from a high-pressure pump in a pressure accumulating pipe and injecting fuel into the respective cylinders from a fuel injection valve provided in each cylinder of an internal combustion engine via the accumulating pipe. An injector, which is a low-pressure pump that supplies fuel to the high-pressure pump, an operation start notifying unit that notifies the operation start time of the internal combustion engine, and the low-pressure pump before the operation start time that the operation start notification unit notifies. Control means for starting the driving of the low pressure pump to control the fuel discharge of the low pressure pump, and a communication passage for flowing the discharge fuel of the low pressure pump into the pressure accumulation pipe when the fuel pressure in the pressure accumulation pipe is lower than the discharge pressure of the low pressure pump. And a fuel injection device. 2. The fuel injection device according to claim 1, wherein the operation start notifying unit is an ignition switch. 3. The control means controls the discharge pressure from the low pressure pump to the high pressure pump so that the discharge pressure of the high pressure pump becomes equal to or higher than a predetermined pressure. Fuel injection device. 4. The fuel injection device according to claim 3, wherein the predetermined pressure is a pressure value necessary for operating the internal combustion engine. 5. The fuel injection device according to claim 3, wherein the predetermined pressure is a maximum discharge pressure of the low pressure pump. 6. The fuel injection according to claim 3, wherein the control means performs control to reduce the discharge pressure of the low pressure pump to a required predetermined pressure of the high pressure pump after the operation of the internal combustion engine is started. apparatus. 7. The control means continues the control for increasing the discharge pressure of the low pressure pump to a required predetermined pressure of the high pressure pump or more for a predetermined period or more, and after the lapse of the predetermined period, sets the required pressure of the high pressure pump to the required predetermined pressure. The fuel injection device according to claim 3, wherein control is performed to reduce the discharge pressure of the low-pressure pump. 8. The pressure accumulating pipe is provided with pressure detecting means for detecting a fuel pressure in the pressure accumulating pipe, and when the fuel pressure in the pressure accumulating pipe reaches or exceeds a predetermined pressure, a required predetermined pressure of a high pressure pump. The fuel injection device according to claim 3, wherein the discharge pressure of the low-pressure pump is reduced. 9. The communication passage comprises a flow passage formed in the high-pressure pump, a pipe connecting the high-pressure pump and the accumulator pipe, and a check valve provided in the pipe. The fuel injection device according to claim 1, which is characterized in that. 10. The communication passage includes a bypass pipe that connects the low pressure pump and the pressure accumulating pipe without passing through the high pressure pump, and a check valve provided in the bypass pipe. The fuel injection device according to claim 1. 11. The valve opening pressure of the check valve is set to be equal to or lower than a discharge pressure of the low pressure pump.
Alternatively, the fuel injection device according to item 10.