JP2003083103A - Accumulator fuel injection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a common rail type fuel injection device with improved reliability by preventing high pressure in a high-pressure supply pipe 6 and a common rail 3 at the engine stop transition time when an ignition switch is turned off from a turn-on condition. SOLUTION: Power supply to an inlet flow control valve 7 is not stopped simultaneously when an ignition switch is turned off, but power is supplied to the inlet flow control valve 7 for a predetermined timed even after the ignition switch is turned off, so as to restrain the flow rate of fuel to be sucked in the high-pressure supply pump 6. Additionally, even after the ignition switch 2 is turned off, an injector 2 is driven for a predetermined time to an extent not to inject fuel to an engine 1. Thereby, the fuel in the high-pressure supply pump 6, the common rail 3, and the injector 2 is returned to a fuel tank 4 from a leak piping 12 or the like, to prevent high pressure in the high-pressure supply pump 6 and the common rail 3, resulting in improvement of reliability.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure-accumulation fuel injection device, and more particularly to a common-rail fuel injection device that injects high-pressure fuel accumulated in a common rail to an engine through an injector.

[0002]

2. Description of the Related Art Conventionally, in a common rail fuel injection device known as a fuel injection system for a diesel engine, a high pressure supply pump rotatably driven by a crankshaft of a diesel engine pressurizes fuel drawn from a fuel tank. It is configured to increase the pressure and accumulate the pressure in the common rail, and to inject and supply the high pressure fuel accumulated in the common rail to the engine through an injector.

The common rail fuel injection system is
The fuel pressure in the common rail (actual common rail pressure) detected by the fuel pressure sensor is detected, and the high pressure supply pump of the high pressure supply pump is adjusted so that this actual common rail pressure substantially matches the target common rail pressure set according to the operating state of the engine. The amount of fuel discharged from the pressurizing chamber to the common rail is feedback-controlled. The high-pressure supply pump is equipped with a pump flow control valve for adjusting the amount of fuel discharged from the pressurizing chamber to the common rail, and the pump flow control valve is fully opened when energization is stopped. A normally open type that is in a state is generally used.

[0004]

However, in the conventional common rail fuel injection device, the vehicle occupant turns the ignition switch from the on (IG / ON) state to the off (IG / OFF) in order to stop the operation of the engine. In the engine stop transition state, the energization of the pump flow control valve is stopped, and the valve state of the pump flow control valve is in the fully open state, so that the fuel supply amount from the high-pressure supply pump to the common rail becomes the maximum amount. Further, the control of the injector is in the non-injection state of the energization cut at the same time as the IG / OFF.

Therefore, at the time of engine stop transition, even if the ignition switch is turned off, the high pressure supply pump is rotated at a rotation speed lower than the idle rotation speed, and fuel is pumped from the high pressure supply pump to the common rail. Become. As a result, the fuel pressure in the common rail (actual common rail pressure) may reach the target common rail pressure during idling or higher.

As a result, when the engine is started just after the engine is stopped (including restart when the engine fails to start during cold start), the actual common rail pressure at engine start becomes equal to or higher than the target common rail pressure at idle. Therefore, there is a problem in that large vibration and noise are generated when the engine is started. Further, even when the engine is stopped, that is, when the engine speed is extremely low, the high-pressure supply pump and the common rail become high in pressure, which causes a problem that reliability is deteriorated.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a pressure accumulating fuel injection device capable of improving reliability by preventing the high pressure supply pump and the common rail from becoming high in pressure at the time of engine stop transition. is there. Another object of the present invention is to provide a pressure-accumulation fuel injection device that can reduce the actual common rail pressure to a value equal to or lower than the target pressure during stop when the engine shifts to stop.

[0008]

According to the first aspect of the present invention, when the engine is stopped, the actual fuel pressure detected by the fuel pressure detecting means is decreased to a value equal to or lower than the stop target pressure. By driving the discharge amount varying means, the high pressure supply pump and the inside of the common rail do not become high pressure when the engine is stopped, and the reliability is not deteriorated.

According to the second aspect of the present invention, by driving the injector so as to reduce the actual fuel pressure detected by the fuel pressure detecting means to a value equal to or lower than the target pressure at the time of stop when the engine is stopped. When the engine is stopped, the high-pressure supply pump and the common rail will not have a high pressure, and the reliability will not be reduced.

According to the third aspect of the present invention, when the engine is stopped, the discharge amount varying means and the injector are arranged so that the actual fuel pressure detected by the fuel pressure detecting means is lowered below the target pressure during stop. By driving, it is possible to achieve the same effects as the inventions according to the first and second aspects.

According to the fourth aspect of the present invention, the target pressure during stop is set to a value lower than the target pressure during idle set according to the idle speed, so that the engine starts just after the engine is stopped. Even when the engine starts, the actual fuel pressure is lower than the idle target pressure,
No big vibration or noise is generated when starting the engine.

According to the fifth aspect of the present invention, the pump flow rate control valve that is fully opened when de-energized is used as the discharge amount varying means. Then, as a pump flow control valve, a discharge amount adjusting solenoid valve for adjusting the discharge amount of fuel from the pressurizing chamber of the high pressure supply pump to the common rail, or a suction amount of fuel sucked into the pressurizing chamber of the high pressure supply pump is used. It is characterized by using a solenoid valve for adjusting the suction amount to be adjusted.

According to the sixth aspect of the invention, when the injector is driven so as to reduce the actual fuel pressure below the target pressure at the time of engine stop transition, it means that the fuel is injected and supplied from the injector to the engine. It is to hit the injector dry to the extent that it is not done. This makes it possible to reduce the actual fuel pressure detected by the fuel pressure detection means to the engine stop target pressure or lower when the engine is stopped.

According to the seventh aspect of the present invention, when the injector is driven so as to reduce the actual fuel pressure below the target pressure at the time of engine stop transition, the injection of fuel from the injector to the engine is stopped. To delay until a predetermined condition is satisfied. This makes it possible to reduce the actual fuel pressure detected by the fuel pressure detection means to the engine stop target pressure or lower when the engine is stopped.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described based on examples with reference to the drawings. [Structure of First Embodiment] FIGS. 1 to 3 show a first embodiment of the present invention, and FIG. 1 is a view showing the entire structure of a common rail fuel injection device.

The common rail fuel injection system of this embodiment is a multi-cylinder diesel engine (hereinafter abbreviated as engine).
1, a plurality of injectors 2 for injecting high-pressure fuel into the combustion chamber of each cylinder, a common rail 3 which is a kind of surge tank for accumulating high-pressure fuel, a well-known low-pressure supply pump 5 for pumping fuel from the fuel tank 4, A high-pressure supply pump 6 that pressurizes the fuel pumped up by the low-pressure supply pump 5 to a high pressure and sends it to the common rail 3, and a plurality of injectors 2 and an electronic control unit (hereinafter referred to as ECU) 10 that controls the high-pressure supply pump 6. Is equipped with.

Each injector 2 is connected to the downstream ends of a plurality of branch pipes branched from the common rail 3, and the engine 1
Is a fuel injection nozzle for injecting and supplying high-pressure fuel into the combustion chamber of each cylinder. From these injectors 2 to the engine 1
The fuel injection into the fuel injection system is electronically controlled by energizing and deenergizing (ON / OFF) an injection control electromagnetic valve (not shown) as an electromagnetic actuator provided in the middle of the branch pipe.

That is, the injector 2 injects and supplies the high-pressure fuel accumulated in the common rail 3 into the combustion chamber of each cylinder of the engine 1 while the injection control solenoid valve is open. A high pressure (common rail pressure) corresponding to the fuel injection pressure needs to be continuously accumulated in the common rail 3, and for this reason, a high pressure supply for discharging high pressure fuel through the fuel pipe (high pressure passage) 11 It is connected to the discharge port of the pump 6. A pressure limiter (not shown) is provided in the fuel pipe 11 or the common rail 3 to prevent the common rail pressure from becoming abnormally high. Further, the leaked fuel from the injector 2 and the leaked fuel from the high-pressure supply pump 6 are returned to the fuel tank 4 via the leak pipe (low-pressure passage) 12.

The high-pressure supply pump 6 includes a low-pressure supply pump (feed pump) 5 for pumping the fuel in the fuel tank 4 as the pump shaft 14 rotates in accordance with the rotation of the crankshaft 13 of the engine 1, and the pump shaft 14. It has a driven plunger (not shown) and a pressurizing chamber (plunger chamber) that pressurizes fuel by the reciprocating motion of the plunger. The high-pressure supply pump 6 is the low-pressure supply pump 5
Is a supply pump that pressurizes the fuel sucked by and discharges high-pressure fuel from the discharge port to the common rail 3. An inlet metering valve 7 as an electromagnetic actuator that opens and closes the fuel passage is attached to the fuel passage to the pressurizing chamber of the high-pressure supply pump 6.

The inlet metering valve 7 corresponds to the discharge amount varying means of the present invention, and is electronically controlled by a control signal from the ECU 10 so that the amount of fuel sucked into the pressurizing chamber of the high pressure supply pump 6 is reduced. An intake pressure adjusting solenoid valve for adjusting the intake amount changes the injection pressure supplied from each injector 2 to the engine 1, that is, the common rail pressure. The inlet metering valve 7 is a normally open type pump flow control valve in which the valve state is fully opened when the energization is stopped.

The ECU 10 has a CPU for performing control processing and arithmetic processing, and an RO for storing various programs and data.
A microcomputer having a well-known structure including functions of M, RAM, input circuit, output circuit, power supply circuit, injector drive circuit, pump drive circuit, and the like is provided. The sensor signals from the various sensors are A /
It is configured so that it is A / D converted by the D converter and then input to the microcomputer.

Then, the ECU 10 determines the optimum fuel injection timing and fuel injection amount (= injection period) according to the operating state of the engine 1, and the injector drive circuit (E) (not shown).
Fuel injection control means for driving the injection control solenoid valve of the injector 2 via the DU). That is, the ECU 10
Is engine operating information such as engine speed (hereinafter referred to as engine speed: NE) detected by the rotation speed sensor 21 and accelerator opening (ACCP) detected by the accelerator opening sensor 22, and further a cooling water temperature sensor. Engine cooling water temperature (TH
W) is added to calculate the target injection amount, and in order to achieve this target injection amount, the injection control of each injector 2 is performed according to the injector energization time command calculated from the actual common rail pressure for each operating state. The control signal is output to the solenoid valve for use. As a result, the engine 1 is operated.

The ECU 10 also determines the optimum fuel injection pressure according to the operating state of the engine 1, that is, the common rail pressure, and the inlet metering valve 7 of the high pressure supply pump 6 via a pump drive circuit (EDU) not shown. Is a fuel pressure control means for driving. That is, the ECU 10 controls the engine speed (N
E) and engine operating information such as the accelerator opening (ACCP) detected by the accelerator opening sensor 22 and the correction of the engine cooling water temperature (THW) detected by the cooling water temperature sensor 23 are taken into consideration to determine the target common rail pressure. In order to calculate and achieve this target common rail pressure, a control signal is output to the inlet metering valve 7 of the high-pressure supply pump 6.

Furthermore, more preferably, the actual fuel injection pressure injected and supplied from each injector 2 to the engine 1,
That is, the common rail pressure sensor 25 that detects the actual common rail pressure (Pr) is arranged on the common rail 3, and feedback control is performed so that the actual common rail pressure (Pr) detected by the common rail pressure sensor 25 matches the target common rail pressure. . The target injection amount, the fuel injection timing, the target common rail are detected based on detection signals (engine operation information) from other sensors (for example, intake air temperature sensor, fuel temperature sensor, intake pressure sensor, cylinder discrimination sensor, injection timing sensor, etc.). The pressure may be corrected.

Here, for the purpose of starting the engine 1, the ECU 10 turns on the ignition switch by the vehicle occupant (IG / ON), and then starts energizing the starter to rotate the crankshaft 13 of the engine 1 to the minimum required rotation. The engine cooling water temperature (THW) detected by the cooling water temperature sensor 23 or the engine speed (NE) detected by the rotation speed sensor 21 when cranking at a speed or higher
The optimum fuel injection start pressure for starting the engine 1 according to
In other words, it has a starting target pressure determining means for calculating the starting target common rail pressure (hereinafter referred to as the starting target pressure). It should be noted that the target pressure at startup is the engine cooling water temperature (T
The lower the HW), the higher the setting.

Further, the ECU 10 detects the rotation speed sensor 21 at the time of engine stop transition in which the vehicle occupant turns the ignition switch from the on (IG / ON) state to the off (IG / OFF) in order to stop the operation of the engine 1. A value lower than an idle target common rail pressure (hereinafter referred to as idle target pressure) set as a target common rail pressure when the engine speed (NE) is set to an idle speed (for example, about 750 to 850 rpm) is calculated, The value is used as the target common rail pressure (Ps
t: hereinafter referred to as target pressure during stop).

[Control Method of First Embodiment] Next, a control method of the common rail fuel injection apparatus of the present embodiment will be briefly described with reference to FIGS. 1 to 3. Here, FIG. 2 is a flowchart showing a method for controlling the fuel injection pressure (common rail pressure) at the time of engine stop transition, and FIG. 3 is the ECU power supply voltage at engine stop transition after IG.ON to IG.OFF, IG. It is a time chart showing the behavior of ON → OFF, the opening of the inlet metering valve of the high-pressure supply pump, the injector (INJ) drive pulse, the engine speed (NE), and the actual common rail pressure.

In step S1, engine parameters representing the operating state of the engine, that is, engine speed (N
E), engine operation information such as accelerator opening (ACCP), engine cooling water temperature (THW), etc. is taken in. Next, the following control is performed based on the engine parameters fetched in step S1.

In step S2, it is determined whether or not the ignition switch is within a predetermined time (for example, 1 to 2 seconds) from IG.ON to IG.OFF. And
If it is within a predetermined time after IG / ON → OFF, the control processing and the arithmetic processing of step S4 and subsequent steps relating to the method of controlling the common rail pressure at the time of engine stop transition of the present invention are performed, and IG / ON → If the predetermined time has elapsed after the power was turned off, a command value for turning off the power supply voltage of the ECU 10 is output to the output stage of the ECU 10 in step S3.

In step S4, a target pressure during stop (for example, 20 MPa) Pst, which is a value lower than the target pressure during idle (for example, about 30 to 35 MPa), is calculated, and in step S5, it is detected by the common rail pressure sensor 25. The actual common rail pressure (P, which is the actual pressure of fuel from the pressurizing chamber of the high-pressure supply pump 6 to the common rail 3)
r) is taken in. Then, in step S6, it is determined whether the engine speed (NE) at that time is within a predetermined range α. Here, for example, 750 rpm ≧ α> 0 rpm. If it is within the predetermined range α, it is considered that the common rail pressure may still be increased, and the control processing from step S7 is executed.

In step S7, the actual common rail pressure (P) which is the actual pressure of the fuel taken in in step S5 is obtained.
It is determined whether or not r) is higher than the target pressure during stop (Pst) fetched in step S4. If the actual common rail pressure is higher than the idling drive pulse output to the injection control solenoid valve of the injector (INJ) 2 in order to lower the actual common rail pressure due to fuel injection or dynamic leakage in step S8. The short stop drive pulse T is set as a pulse width command value according to the pressure deviation value f (Pr-Pst) between the actual common rail pressure (Pr) and the target stop pressure (Pst).

Then, in step S10, the step S
The pulse width command value T of 8 is set in the output stage of the ECU 10. The stop drive pulse width is a pulse width to the extent that fuel injection into the engine 1 is not performed (injection of the injector 2). At the same time, in step S9, the valve opening degree of the inlet metering valve 7 of the high-pressure supply pump 6 is set to a pressure deviation value f between the actual common rail pressure (Pr) and the target pressure at stop (Pst).
An opening degree command value (Di) of the inlet metering valve 7 is calculated so as to control according to the deviation from (Pr-Pst). Then, in step S11, the opening command value (Di) of the inlet metering valve 7 in step S9 is set in the output stage of the ECU 10.

If the engine speed (NE) is outside the predetermined range α in step S6, or if the actual common rail pressure (Pr) becomes equal to or lower than the target pressure at stop (Pst) in step S7, the injector (INJ )
In order to stop the operation of No. 2, the pulse width command value T is set to 0, the injector (INJ) drive signal is turned off, and the drive of the injector (INJ) 2 is stopped. At the same time, in step S13, the command to the inlet metering valve 7 of the high-pressure supply pump 6 is the command value of the previous inlet metering valve 7 (Di- 1) is set as the output value (OUT) and is set in the output stage of the ECU 10.

[Effects of the First Embodiment] As described above, in the common rail fuel injection system of the present embodiment, a predetermined time (for example, 1 to 2 seconds) has passed since the ignition switch was switched from IG / ON to IG / OFF. Detected by the common rail pressure sensor 25 during engine stop transition within
The actual common rail pressure (Pr), which is the actual pressure of fuel from the pressurizing chamber of the high-pressure supply pump 6 to the common rail 3, is lower than the idle target pressure (for example, about 30 to 35 MPa), and the target stop pressure (Pst). : For example, 20MP
a) The opening of the inlet metering valve 7 and the pulse width of the injector 2 are controlled so as to decrease below a).

That is, the stop drive pulse T, which is output to the injection control solenoid valve of the injector (INJ) 2 and is shorter than the idle drive pulse, is applied to the actual common rail pressure (P
r) and the pressure deviation value f (P
r-Pst) and set the valve opening of the inlet metering valve 7 of the high-pressure supply pump 6 to the actual common rail pressure (P
r) and the pressure deviation value f (P
It is set according to the deviation from r-Pst).

As a result, even if the normally open type inlet metering valve 7 is in a fully opened state when the energization is stopped, the inlet metering valve 7 is energized at the same time when the ignition switch is turned off. Instead of stopping, the inlet metering valve 7 is energized and the high pressure supply pump 6 is turned on within a predetermined time after the ignition switch is turned off.
The flow rate of fuel drawn into the pressurizing chamber can be suppressed.

Further, the ignition switch is not turned off at the same time when the ignition switch is turned off but the power supply to the injection control solenoid valve of the injector 2 is not stopped.
By driving the injection control solenoid valve of the injector 2 to such an extent that fuel injection into the engine 1 is not performed within a predetermined time even after FF, a dynamic leak occurs inside the high-pressure supply pump 6.
The fuel in the common rail 3 and the injector 2 is returned from the leak pipe 12 to the fuel tank 4, and the high pressure supply pump 6
The inside of the common rail 3 and the inside of the common rail 3 are prevented from having a high pressure to improve reliability.

Further, since the target pressure at stop (Pst) is set to a value lower than the target pressure at idle set according to the idle speed, the fuel from the pressurizing chamber of the high pressure supply pump 6 to the common rail 3 is The actual common rail pressure (Pr), which is the actual pressure of the
0 to 35 MPa), which is lower than the stop target pressure (Pst: 20 MPa, for example).
Even when the engine is started just after the engine is stopped (including restart when the engine fails to start during cold start), the actual common rail pressure (Pr) at engine start becomes lower than the target pressure at idle, resulting in large vibration at engine start. There is no noise.

[Second Embodiment] FIG. 4 shows a second embodiment of the present invention. FIG. 4 shows the ECU power supply voltage at the time of engine stop transition from IG.ON to IG.OFF, IG.ON.
→ OFF, opening of inlet metering valve of high-pressure supply pump, injector (INJ) drive pulse, engine speed (N
E) is a time chart showing the behavior of the actual common rail pressure.

In the common rail fuel injection system of this embodiment, the ignition switch is changed from IG.ON to IG.O.
When the engine is stopped within a predetermined time (for example, 1 to 2 seconds) after FF, the ignition switch is turned off.
The drive for outputting to the injection control solenoid valve of the injector 2 until a predetermined time elapses after the ignition switch is turned off, instead of stopping the energization of the injection control solenoid valve of the injector 2 at the same time as the F is performed. The pulse is maintained to be the idle injection pulse, and the stop of fuel injection into the engine 1 is delayed.

As a result, fuel is injected from the injector 2 until a predetermined time elapses after the ignition switch is turned off, so that the fuel in the high-pressure supply pump 6, the common rail 3 and the injector 2 leaks. It is returned to the fuel tank 4 through the pipe 12 to prevent the high pressure supply pump 6 and the common rail 3 from becoming high pressure, thereby improving reliability.

Incidentally, although not shown, from the idle injection pulse to the blanking pulse or 0 pulse depending on the pressure deviation value f (Pr-Pst) between the actual common rail pressure (Pr) and the target pressure at stop (Pst). It is also possible to map and use. Further, a stop delay control for delaying the injection stop of the injector 2 (second embodiment) and a pulse width changing control for setting a drive pulse width for the injector 2 to a stop drive pulse shorter than an idle drive pulse (first)
Examples) may be combined.

[Modification] In the present embodiment, an example in which the starting target common rail pressure (starting target pressure) is determined according to the engine speed (NE) or the engine cooling water temperature (THW) has been described. Since the rotation speed of the starter becomes slower as the temperature decreases, the battery voltage decreases as the ambient temperature in the engine room, which is affected by the engine temperature, decreases. For this reason, the engine speed and the battery voltage have a correlation with the engine temperature, and therefore either one may be used to determine the target common rail pressure at startup (target pressure at startup).

In this embodiment, the common rail pressure sensor 2
5 to the common rail 3 directly, the common rail 3
Although the fuel pressure (actual common rail pressure) accumulated in the fuel is detected, the fuel pressure detecting means is used as fuel between the plunger chamber (pressurizing chamber) of the high-pressure supply pump 6 and the fuel passage in the injector 2. The pressure of the fuel discharged from the pressurizing chamber of the high-pressure supply pump 6 may be detected by attaching it to a pipe or the like.

In this embodiment, an inlet metering valve (intake amount adjusting solenoid valve) 7 for changing (adjusting) the intake amount of the fuel sucked into the plunger chamber (pressurizing chamber) of the high-pressure supply pump 6 is provided. However, a discharge amount adjusting solenoid valve that changes (adjusts) the discharge amount of fuel from the plunger chamber (pressurizing chamber) of the high-pressure supply pump 6 to the common rail 3 may be provided. It should be noted that a normally open type solenoid valve in which the valve opening of the discharge amount adjusting solenoid valve or the suction amount adjusting solenoid valve is fully opened when the solenoid valve is de-energized may be used. A solenoid valve of a type in which the valve opening of the solenoid valve for intake or the solenoid valve for adjusting the intake amount is fully opened when the solenoid valve is energized may be used.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an overall structure of a common rail fuel injection device (first embodiment).

FIG. 2 is a flowchart showing a method of controlling a common rail pressure when shifting to engine stop (first embodiment).

[Fig. 3] ECU power supply voltage at the time of engine stop transition from IG / ON to IG / OFF, IG / ON to OFF, opening of metering valve at inlet of high pressure supply pump, injector drive pulse, engine speed, actual common rail It is a time chart which showed the behavior of pressure (1st example).

[Fig. 4] ECU power supply voltage at the time of engine stop transition from IG / ON to IG / OFF, IG / ON to OFF, opening of metering valve at inlet of high pressure supply pump, injector drive pulse, engine speed, actual common rail It is a timing chart showing the behavior of pressure (second embodiment).

[Explanation of symbols]

1 Engine 2 Injector 3 Common Rail 6 High-Pressure Supply Pump 7 Inlet Metering Valve (Discharge Amount Adjusting Means, Pump Flow Control Valve, Suction Intake Solenoid Valve) 10 ECU (Fuel Injection Control Means, Fuel Pressure Control Means) 25 Common Rail Pressure Sensor (Fuel pressure detection means)

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) F02M 59/44 F02M 59/44 HF term (reference) 3G066 AA07 AC09 AD02 BA22 BA46 CA05U CE21 DA06 DB19 DC04 DC09 DC14 DC18 3G092 AA02 BB01 BB08 BB10 CA01 DG09 EA02 EA09 EA12 EA16 FA06 FA14 FA26 FA32 GA10 HB01X HB03X HE01Z HE08Z HF08Z HF20Z 3G301 HA02 JA03 JA37 KA04 KA26 NE04Z19P08Z16P08 NE16 NE12 NE16 NE10

Claims (7)

[Claims] 1. A high-pressure supply pump that is rotationally driven by an engine to pressurize and suck up the drawn fuel, and (b) a common rail that stores the high-pressure fuel discharged from the high-pressure supply pump. c) an injector for injecting and supplying the high pressure fuel accumulated in the common rail to the engine; (d) a discharge amount varying means for changing the discharge amount of the fuel from the high pressure supply pump to the common rail; (e) the common rail A fuel pressure detecting means for detecting the fuel pressure in the inside, and (f) the discharge amount so as to reduce the actual fuel pressure detected by the fuel pressure detecting means at the time of engine stop transition to a target pressure at the time of stop or less. An accumulator fuel injection device, comprising: a fuel pressure control unit that drives a variable unit. 2. A high-pressure supply pump, which is rotationally driven by an engine to pressurize intake fuel to increase its pressure, and (b) a common rail for accumulating high-pressure fuel discharged from this high-pressure supply pump. c) an injector for injecting and supplying the high pressure fuel accumulated in the common rail to the engine; (d) a discharge amount varying means for changing the discharge amount of the fuel from the high pressure supply pump to the common rail; (e) the common rail A fuel pressure detecting means for detecting the fuel pressure in the inside of the injector; and (f) the injector for changing the actual fuel pressure detected by the fuel pressure detecting means at the time of engine stop transition to a target pressure at the time of stop or less. An accumulator fuel injection device, comprising: a fuel injection control unit that is driven. 3. A high-pressure supply pump, which is rotationally driven by an engine to pressurize intake fuel to increase its pressure, and (b) a common rail for accumulating high-pressure fuel discharged from this high-pressure supply pump. c) an injector for injecting and supplying the high pressure fuel accumulated in the common rail to the engine; (d) a discharge amount varying means for changing the discharge amount of the fuel from the high pressure supply pump to the common rail; (e) the common rail A fuel pressure detecting means for detecting the fuel pressure in the inside, and (f) the discharge amount so as to reduce the actual fuel pressure detected by the fuel pressure detecting means at the time of engine stop transition to a target pressure at the time of stop or less. Fuel pressure control means for driving the variable means, and (g) an actual fuel pressure detected by the fuel pressure detection means at the time of engine stop transition, Serial stop so reduces the target pressure below accumulator fuel injection apparatus characterized by comprising a fuel injection control means for driving the injector. 4. The pressure-accumulation fuel injection device according to claim 1, wherein the target pressure at stop is a value lower than a target pressure at idle set according to an idle speed. Is a pressure-accumulation fuel injection device. 5. The pressure-accumulation fuel injection device according to any one of claims 1 to 4, wherein the discharge amount varying means is a pump flow rate control valve that is fully opened when de-energized. The valve adjusts the discharge amount adjusting solenoid valve for adjusting the discharge amount of fuel from the pressurizing chamber of the high pressure supply pump to the common rail, or the suction amount of fuel sucked into the pressurizing chamber of the high pressure supply pump. A pressure-accumulation fuel injection device, which is a solenoid valve for adjusting the intake amount. 6. The pressure-accumulation fuel injection device according to claim 2 or 3, wherein the injector is driven so as to reduce the actual fuel pressure below the stop target pressure when the engine is stopped. Is a fuel injection device for accumulating fuel, characterized in that the injector is idled to such an extent that fuel is not supplied from the injector to the engine. 7. The pressure-accumulation fuel injection device according to claim 2 or 3, wherein the injector is driven so as to reduce the actual fuel pressure to the stop target pressure or less when the engine is stopped. Is to delay injection stop of fuel from the injector to the engine until a predetermined condition is satisfied.