JPH1130150A - Accumulator type fuel injection device - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To control fuel pressure in a common rail with high accuracy and responsiveness. A high-pressure fuel injection pump supplies high-pressure fuel to a common rail, and supplies fuel to each fuel injection valve from the common rail. The ECU 20 has a fuel pressure sensor 31
The amount of fuel pumped from the fuel injection pump 5 to the common rail is controlled so that the actual common rail pressure matches the fuel pressure detected in the above and the target fuel pressure set according to the engine operating state. Further, the ECU calculates the fuel injection pump rotation speed,
The amount of fuel leaked from the fuel system is calculated based on the pump operation state such as the fuel temperature detected by the temperature sensor 33, and the fuel pumping amount is corrected based on the leak amount.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure accumulating fuel injection device, and more particularly, to a pressurized fuel stored in a pressure accumulating chamber (common rail) and injecting fuel into an internal combustion engine from a fuel injection valve connected to the pressure accumulating chamber. The present invention relates to a common rail type fuel injection device.

[0002]

2. Description of the Related Art Fuel is supplied from a high-pressure fuel pump to a common accumulator (common rail), and a fuel injection valve for each cylinder is connected to the accumulator to supply high-pressure fuel stored in the accumulator to each cylinder of the internal combustion engine. 2. Description of the Related Art There is known a so-called pressure accumulation type (common rail type) fuel injection device that injects fuel into a fuel cell.

In an accumulator type fuel injection device, the injection rate of a fuel injection valve is controlled by the fuel pressure in a common rail, and the fuel injection amount is controlled by both the fuel pressure in the common rail and the valve opening (fuel injection) time of the fuel injection valve. Is done. For this reason, in the accumulator type fuel injection device, it is necessary to accurately control the fuel pressure in the common rail according to the engine load state.

An example of such an accumulator type fuel injection device is disclosed in, for example, JP-A-64-73166. The device disclosed in this publication sets a target pressure of fuel pressure in the common rail according to the engine load and the number of revolutions, and sets a common rail from the fuel pump so that the actual fuel pressure in the common rail detected by the pressure sensor becomes the target pressure. The amount of fuel pumped to the hopper is controlled.

In general, in a pressure-accumulation type fuel injection device, it is necessary to control the fuel pressure in the common rail to a target pressure which changes rapidly in accordance with the engine load condition. Moreover, it is necessary to control with high precision. For this reason, the feedforward control and the feedback control are used in combination for the control of the fuel pumping amount from the normal fuel pump. That is, the fuel pumping amount is usually an amount including the sum of the feedforward amount determined from the common rail target fuel pressure and the fuel injection amount command value and the feedback amount determined by the deviation of the actual common rail fuel pressure from the target fuel pressure. Is calculated. Here, the feedforward amount is a value for roughly adjusting the common rail pressure to a value near the target pressure, and the feedback amount is a value for finely adjusting the common rail fuel pressure to exactly match the target pressure.

[0006] Generally, in the control of the fuel pumping amount using the feedforward amount and the feedback amount as described above,
The feedforward amount is set in advance for each combination of the target pressure and the fuel injection amount command value and stored in the control device as a numerical map. From this map, the feedforward amount is determined based on the target pressure and the fuel injection amount command value. Is read. As a result, even in the case where the engine load condition fluctuates rapidly, such as during transient operation, the feedforward amount is set to an appropriate value at high speed, and the common rail fuel pressure is responsive to the target pressure in the vicinity of the target pressure with good responsiveness. Controlled by value. Also, the feedback amount is usually
Since the actual fuel pressure in the common rail is determined by the proportional integral control based on the deviation from the target pressure or the like, the fuel pressure in the common rail is accurately controlled to the target pressure by the feedback amount. That is, the fuel pressure in the common rail can be controlled to the target pressure with high responsiveness and high accuracy by controlling the fuel pump pressure feed amount using the feedforward amount and the feedback amount.

[0007]

However, since the feedforward amount is set only by the target fuel pressure and the fuel injection amount command value, the target fuel pressure and the fuel injection amount are changed if conditions such as the pump speed are different. With the feedforward amount set based only on the command value, the fuel pressure in the common rail may not be able to be controlled near the target pressure.

For example, the fuel pumping amount of the fuel pump set as described above does not entirely contribute to the increase in the pressure of the common rail. In fact, a part of the pumping fuel is slid inside the fuel pump or the fuel injection valve. It leaks from the moving part and returns to the fuel tank without contributing to the increase in the pressure of the common rail. In addition, the amount of leak per unit time from these sliding parts etc. (hereinafter, such as the leak from these sliding parts etc., which is constantly occurring, is generated by the fuel injection operation of the fuel injection valve) In order to distinguish from leaks that occur (dynamic leaks), the "static leaks" change with fuel temperature (ie, fuel viscosity). Further, even when the static leak amount per unit time is the same, the time per one cycle of the operation of the fuel pump changes according to the pump rotation speed. It will vary with the number. For this reason, even if the target fuel pressure and the fuel injection command value are the same, if the pump rotation speed or the fuel temperature changes, the fuel per one cycle of the pump operation required to control the common rail pressure close to the target pressure is required. The amount of pumping (ie, the amount of feedforward) will be different. Therefore, depending on the conditions of the fuel temperature and the pump rotational speed, the feedforward amount stored in advance in the numerical map may make it impossible to sufficiently bring the common rail fuel pressure close to the target pressure.

Even in this case, the fuel pressure in the common rail accurately matches the target pressure due to the feedback amount after a certain period of time has elapsed, but the fuel pressure in the common rail and the target pressure after the coarse adjustment based on the feedforward amount. If the difference is large, it takes time for the common rail fuel pressure to converge to the target pressure,
There is a problem that the responsiveness to a change in the engine load state of the fuel pressure is reduced.

SUMMARY OF THE INVENTION In view of the above problems, the present invention provides a pressure-accumulation type fuel injection system capable of controlling the fuel pressure in a common rail to a target pressure with high accuracy and responsiveness irrespective of changes in the pump speed and fuel temperature. It is intended to provide.

[0011]

According to the first aspect of the present invention, a pressure accumulating chamber for storing pressurized fuel, a fuel injection valve for injecting the fuel in the pressure accumulating chamber to the internal combustion engine, and A fuel injection pump for supplying fuel, and control means for setting a target value of the amount of fuel supplied from the fuel injection pump to the accumulator so that the fuel pressure in the accumulator becomes a predetermined target pressure. In the pressure-accumulation type fuel injection device, the control means is driven by the fuel injection pump based on an operation state detection means for detecting an operation state of the fuel injection pump and a pump operation state detected by the operation state detection means. Fuel leak amount calculating means for calculating an amount of leak fuel that does not contribute to the pressure rise in the pressure storage chamber, and correcting means for correcting the fuel amount target value according to the calculated leak fuel amount. Accumulator fuel injection system is provided.

According to the second aspect of the present invention, the amount of the leaked fuel is the amount of the static leaked fuel generated from the fuel injection valve and the fuel injection pump regardless of whether or not the fuel injection operation of the fuel injection valve is performed. The pressure accumulating fuel injection device according to claim 1, wherein According to the invention described in claim 3,
The pressure accumulating fuel injection device according to claim 1 or 2, wherein the leak fuel calculating means calculates the leak fuel amount based on a fuel injection pump rotation speed and a fuel temperature.

According to the fourth aspect of the invention, the fuel amount target value is a feedforward amount determined by the target pressure of the accumulator and the fuel injection amount from the fuel injection valve, and the actual fuel in the accumulator. The pressure accumulating fuel injection device according to claim 1, wherein the pressure is set as an amount including a feedback amount determined by a deviation between the pressure and the target pressure, and the correction unit corrects the feedforward amount.

That is, in the invention described in each claim, the leaked fuel amount calculating means calculates the amount of leaked fuel that does not contribute to the increase in the pressure of the accumulator based on the pump operating state such as the pump speed and the fuel temperature. The correction means corrects the target value of the amount of fuel pumped from the fuel injection pump to the accumulator based on the amount of leaked fuel. For example, the correction means corrects the target fuel amount to increase accordingly when the leak fuel amount increases, and corrects the target fuel amount to decrease when the leak fuel amount decreases. As a result, even when the amount of leaked fuel changes due to changes in the pump speed or fuel temperature, the fuel pressure in the pressure storage chamber is controlled to the target fuel pressure with good responsiveness and high accuracy.

[0015]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a diagram showing a schematic configuration of an embodiment when the present invention is applied to an automobile diesel engine. In FIG. 1, reference numeral 1 denotes a fuel injection valve for directly injecting fuel into each cylinder of an internal combustion engine 10 (a four-cylinder diesel engine in this embodiment), and reference numeral 3 denotes a common accumulator (common rail) to which each fuel injection valve 1 is connected. ). The common rail 3 has a function of storing pressurized fuel supplied from a high-pressure fuel injection pump 5 described later and distributing the pressurized fuel to each fuel injection valve 1.

In FIG. 1, reference numeral 7 denotes a fuel tank for storing fuel (light oil in this embodiment) of the engine 10, and reference numeral 9 denotes a low-pressure feed pump for supplying fuel to a high-pressure fuel pump. During operation of the engine, the fuel in the tank 7 is boosted to a constant pressure by the feed pump 9 and supplied to the high-pressure fuel injection pump 5. The fuel discharged from the high-pressure fuel injection pump 5 is supplied to the common rail 3 through the check valve 15 and the high-pressure pipe 17, and is injected from the common rail 3 into each cylinder of the internal combustion engine via each fuel injection valve 1. Is done.

In FIG. 1, reference numeral 19 denotes a return fuel pipe for returning leaked fuel from each fuel injection valve 1 to the fuel tank 7. The leakage fuel from the fuel injection valve will be described later. In FIG. 1, reference numeral 20 denotes an engine control circuit (ECU) for controlling the engine. ECU2
0 is a read only memory (ROM), a random access memory (RAM), a microprocessor (CPU),
The microcomputer is configured as a microcomputer having a known configuration in which input and output ports are connected by a bidirectional bus. EC
U20 controls the opening and closing operation of the suction valve 5a of the high-pressure fuel injection pump 5 to set a target value of the amount of fuel pressure-fed from the fuel injection pump 5 to the common rail 3 according to the engine load, the rotation speed, and the like, as described later. And controls the fuel pressure in the common rail 3 according to the engine load, the number of revolutions, and the like. As a result, the injection rate of the fuel injector becomes the engine load,
It is adjusted according to the rotation speed and the like. Further, the ECU 20 performs fuel injection control for controlling the valve opening time of the fuel injection valve 1 and adjusting the amount of fuel injected into the cylinder according to the engine load, the number of revolutions, and the like.

In this embodiment, as described later, E
The CU 20 functions as a leak fuel amount calculating unit that calculates a leak fuel amount based on the rotation speed of the fuel injection pump 5 (actually, the rotation speed of the engine 10 as described later) and the fuel temperature. For the above control, the input port of the ECU 20
From the fuel pressure sensor 31 and the fuel temperature sensor 33 provided on the common rail 3, voltage signals corresponding to the fuel pressure and the fuel temperature in the common rail 3 as pump operation state parameters are input via the AD converter 34. In addition, a signal corresponding to the operation amount (depressed amount) of the accelerator pedal as an engine load parameter is similarly input from the accelerator opening sensor 35 provided on the engine accelerator pedal (not shown) via the AD converter 34. ing. Further, E
An input port of the CU 20 detects when the crankshaft reaches a reference rotational position (for example, top dead center of the first cylinder) from a crank angle sensor 37 provided on the crankshaft of the engine and a camshaft (not shown). Two signals, a generated reference pulse signal and a rotation pulse signal generated according to the crank rotation angle, are input. The signal from the crank angle sensor 37 is supplied to the ECU
20 is used to calculate the rotation speed of the engine 10 (that is, the rotation speed of the pump 5), and is also used to determine the opening / closing timing of the suction valve 5a of the fuel injection pump 5.

An output port of the ECU 20 is connected to the fuel injection valves 1 via a drive circuit 40 to control the operation of each of the fuel injection valves 1. Is connected to a solenoid actuator that controls the opening and closing of the suction valve 5a, and controls the discharge amount of the pump 5. In the present embodiment, the high-pressure fuel injection pump 5 is in the form of a piston pump having two cylinders. The piston in each cylinder of the pump 5 is reciprocated in the cylinder by being pressed by a cam formed on a piston drive shaft in the pump. In addition, a suction valve that is opened and closed by a solenoid actuator is provided at a suction port of each cylinder. In this embodiment, the piston drive shaft is driven by a crankshaft (not shown) of the engine 10,
It rotates at half the speed of the crankshaft in synchronization with the crankshaft. A cam having two lift portions is formed on a portion of the piston drive shaft of the pump 5 that engages with each piston.
The fuel is discharged in synchronization with the stroke of each cylinder. That is, in the present embodiment, since a four-cylinder diesel engine is used, the two cylinders of the pump 10 are respectively rotated twice while the crankshaft rotates 720 degrees in synchronization with the stroke of the engine cylinder (for example, The fuel is pumped to the common rail 3 (for each exhaust stroke of the cylinder).

The ECU 20 controls the discharge flow rate of the fuel oil from the pump by changing the closing timing of the suction valve 5a in the ascent (pressure feed) stroke of the piston of each cylinder of the pump. That is, the ECU 20 stops energizing the solenoid actuator during the piston descending stroke (suction stroke) of each cylinder and for a predetermined period after the start of the piston ascent stroke (discharge stroke), and maintains the intake valve 5a in the open state. . Thus, even if the piston enters the discharge stroke in each cylinder, the fuel in the cylinder flows back from the suction valve 5a to the tank, and the fuel pressure in the cylinder does not increase. Then, after the elapse of the period, the ECU 20 energizes the solenoid actuator of the suction valve 5a to close the suction valve 5a. As a result, the pressure in the cylinder rises with the rise of the pump piston, and when the pressure in the cylinder becomes higher than the pressure in the common rail 3, the check valve 15 of each cylinder opens, and the high-pressure fuel oil in the cylinder is supplied to the high-pressure pipe. Common rail 3 via 17
To be pumped. Once the suction valve 5a is closed, it is pushed by the fuel pressure while the fuel pressure in the cylinder is high, and is kept closed. Therefore, the amount of fuel pumped to the common rail 3 is determined by the start timing of closing the suction valve 5a of the pump 5. For this reason, the ECU 20 controls the suction valve 5 of each cylinder of the pump 5.
By adjusting the valve closing timing (a) (timing of energizing the solenoid actuator), the effective stroke of the piston of the pump 5 is changed to control the amount of fuel to be pumped to the common rail 3.

In this embodiment, the ECU 20 determines the engine load,
The target common rail fuel pressure is set based on the relationship stored in the ROM in advance according to the rotation speed, and the discharge amount of the pump 5 is adjusted so that the common rail fuel pressure detected by the fuel pressure sensor 31 becomes the set target common rail fuel pressure. Control. Further, the ECU 20 controls the valve opening time (fuel injection time) of the fuel injection valve 1 based on the relationship stored in the ROM in advance according to the engine load and the number of revolutions.

In the fuel injection system of the present embodiment, the fuel pressure of the common rail 3 is changed in accordance with the engine operating conditions, so that the injection rate of the fuel injection valve 1 is adjusted in accordance with the operating conditions. The fuel injection amount is adjusted by changing the injection time according to the engine operating conditions. For this reason, in the common rail fuel injection device of the present embodiment, the fuel injection is performed at the optimum injection rate and the injection amount according to each operating condition of the engine, and the fuel consumption rate is reduced while suppressing combustion noise, vibration, and the like. Exhaust emissions are simultaneously reduced.

As described above, in order to achieve the optimum injection rate and injection amount for each operating condition, in the common rail type fuel injection device of the present embodiment, the fuel pressure in the common rail depends on the operating conditions (load, rotation speed) of the engine. ) Needs to be changed in an extremely wide range (for example, in a range from about 10 MPa to about 150 MPa), and fuel pressure control for controlling the common rail fuel pressure with high responsiveness and high accuracy is required.

Next, the fuel pressure control in this embodiment will be described. In the present embodiment, the fuel supply amount from the fuel pump 5 to the common rail 3 per one cycle of the pump operation, that is, the valve closing timing TF (crank angle) of the suction valve 5a is given by the following equation. TF = TFBSE-TFD + TFBK In this embodiment, as the value of TF increases, the closing timing of the intake valve is retarded, and the amount of fuel supplied to the common rail 3 decreases.

In the above equation, TFBSE indicates a basic pumping amount (feedforward amount), TFD indicates an advance amount for correcting a suction valve opening delay time, and TFBK indicates a feedback amount. Here, TFBSE is a fuel pumping amount determined in accordance with the target common rail fuel pressure PFIN and the fuel injection amount command value, and represents a fuel pumping amount required to bring the common rail fuel pressure approximately close to the target pressure. As described above, in the present embodiment, the target fuel pressure PFIN and the fuel injection amount command value are determined according to engine operating conditions (accelerator opening and engine speed) by a routine (not shown) separately executed by the ECU 20. Is set. The feedforward amount TFBSE is set in advance for each combination of the target pressure and the fuel injection amount command value based on experiments and the like.
The ROM of the CU 20 is stored as a numerical map using the target pressure PFIN and the fuel injection amount command amount, and is read from this map based on the set target pressure PFIN and the fuel injection amount command value.

The TFD is a crank rotation angle corresponding to a time from when a valve closing signal is output to the suction valve 5a to when the suction valve 5a is actually closed. That is, in the present embodiment, the valve opening signal output timing to the suction valve 5a is advanced by the operation delay time of the suction valve 5a. The advance amount TFD for correcting the delay time is set such that the lower the battery voltage (the lower the driving force of the driving solenoid of the suction valve 5a), the lower the battery voltage.
The larger the engine speed is, the larger the value is set.

The feedback amount TFBK is equal to the actual common rail fuel pressure P detected by the fuel pressure sensor 31.
Deviation ΔPC between C and target fuel pressure PFIN (= PC−P
FIN) in accordance with the following equation. TFBK = BKP + BKI where BKP represents a proportional term and a proportional coefficient α and a deviation ΔPC
Is given by the product α × ΔPC, and BKI represents an integral term and is a value that increases and decreases by a fixed amount according to the value of ΔPC as described later.

That is, in this embodiment, the fuel supply amount (TF) from the fuel pump 5 to the common rail 3 is roughly adjusted by the feedforward amount TFBSE read from the map so that the common rail fuel pressure becomes substantially the target value PFIN. Then, the common rail fuel pressure is finely adjusted by the proportional integral control so that the common rail fuel pressure accurately matches the target value based on the feedback amount TFBK.

As described above, the feedforward amount TFBSE is set in advance for each combination of the target pressure PFIN and the fuel injection amount command value. However, each value of the feedforward amount TFBSE is used to rotate the actual engine. Since it is set based on the actual measurement value operated under the condition that the number is constant and the fuel temperature is constant, the leak amount under the actual measurement condition is included.

That is, some of the fuel supplied from the fuel injection pump 5 to the common rail 3 is returned to the fuel tank 7 without contributing to an increase in the pressure of the common rail 3 due to leakage from the fuel injection system. For example, depending on the type of the fuel injection valve, the opening operation of the fuel injection valve is performed using the pressure of the fuel oil, so that a certain amount of fuel oil determined from the fuel injection conditions is returned to the fuel tank with the fuel injection operation. There are forms. More specifically, in this type of valve, when the valve is closed, the fuel pressure is applied to both the lower portion (injection hole side) and the upper portion of the valve body to balance the force applied to the valve body by the fuel pressure. The valve body is pressed against the valve seat by the force of the spring. On the other hand, at the time of fuel injection, the pressure acting on the upper part of the valve body is reduced by allowing the fuel oil on the upper part of the valve body to escape to the return pipe via the solenoid valve. Thus, the valve body is pushed up against the spring by the fuel oil pressure acting on the lower part of the valve body, and the injection hole is opened to perform injection. That is, in this type of fuel injection valve, leak fuel returned from the common rail 3 to the fuel tank 7 is generated with the fuel injection operation.

In addition to the fuel leaked due to the valve opening operation, there is fuel oil that constantly leaks from the clearance of the sliding portion of the fuel injection valve.
The fuel is returned to the fuel tank through a return fuel pipe 19 connecting the fuel tank 7 and the fuel tank 7. In this specification, the leak fuel generated by the fuel injection operation of the fuel injection valve is always referred to as the dynamic leak fuel, the leak fuel from the sliding portion, etc. from the common rail regardless of the fuel injection operation of the fuel injection valve. The leaked fuel returned to the tank will be referred to as static leaked fuel.

In addition to the leak from the sliding part of the fuel injection valve, the fuel leaking from the sliding part clearance of the fuel injection pump 5 exists in the static leak fuel. Of these leaked fuels, the amount of dynamic leaked fuel associated with one fuel injection operation from the fuel injection valve is determined by the fuel injection pressure (that is, the target fuel pressure in the common rail 3) and the fuel injection valve opening time (fuel Injection amount), and does not change significantly depending on the pump rotation speed and fuel temperature. Further, since the fuel pumping operation from the fuel injection pump 5 is performed in synchronization with the engine rotation (fuel injection operation), the dynamic leak amount per one cycle of the pump operation is reduced by the dynamic leakage associated with one fuel injection operation. It becomes equal to the clique amount. For this reason, if the feedforward amount TFBSE is set based on the actual measurement value as described above, the dynamic leak amount included in TFBSE greatly changes from the actual value even if the pump speed or the fuel temperature changes. Never.

However, the static leak amount from the sliding portion of the fuel injection valve and the static leak amount from the sliding portion of the fuel injection pump 5 per one cycle of the pump operation vary depending on the common rail pressure, the fuel temperature, and the pump rotation speed. I do. More specifically, the amount of leaked fuel per unit time from the fuel injection valve and the pump sliding portion changes depending on the fuel pressure (common rail pressure) and the fuel temperature (fuel viscosity). Is higher (the fuel viscosity is lower). In addition, the time required for one cycle of the pump operation changes according to the pump rotation speed (equal to the engine rotation speed in the present embodiment). Therefore, the static leak amount per one pump cycle is the static leak amount per unit time. Even if they are the same, they become smaller as the rotation speed becomes higher. Although the feedforward amount TFBSE set based on the actual measurement value as described above includes the static leak amount corresponding to each fuel pressure, the pump rotation speed and the fuel temperature are measured under constant conditions. Therefore, under operating conditions in which the pump rotation speed and the fuel temperature are different from the values at the time of the actual measurement, the static leak amount included in TFBSE becomes a value different from the actual static leak amount.

For this reason, in the actual operation, if the fuel pumping amount of the pump is determined by using the feedforward amount TFBSE determined from the numerical map, when the pump rotation speed and the fuel temperature change from the conditions at the time of setting the TFBSE. In this case, the common rail pressure cannot be sufficiently brought close to the target pressure, and the responsiveness of the fuel pressure control deteriorates.

Therefore, in the present embodiment, in order to prevent the above problem, the value of the feedforward amount TFBSE set based on the above-described map is corrected based on the pump rotation speed and the fuel temperature and included in the feedforward amount TFBSE. The amount of static leak is adjusted to a value that matches the actual pump operating conditions. For example, fuel injection pump operation 1
Static leakage amount QIL from fuel injector per cycle
S and the static leak amount QPL from the fuel injection pump can be approximately expressed by the following equation.

QILS = A ₁ × (A ₂ + A ₃ × PFI)
N) × A _V / NE QPL = B ₁ × PFIN × B _V / NE where A ₁ , A ₂ , A ₃ and B ₁ are constants, A _V and B _V
Is a coefficient determined by the fuel temperature (fuel viscosity) and is determined in advance by an experiment. NE is the engine speed (pump speed).

In the present embodiment, the ECU 20 sets the feedforward amount TFBSE to the common rail target pressure PFIN
Is determined from a numerical map stored in the ROM based on the fuel injection amount command value and the fuel injection amount, the fuel injection valve, the fuel injection pump and the fuel The static leak amounts QILS and QPL per cycle of the injection pump operation are calculated. Then, static leak amounts QILS ₀ and QPL ₀ per one cycle of the fuel injection pump operation at the time of producing the numerical map of the feedforward amount TFBSE at the fuel temperature and the engine speed.
DQILS (= QILS ₀ −QILS), dQP
Calculate L (= QPL ₀ −QPL). The ECU 20
The correction amount f (dQILS + d of the closing timing of the suction valve 5a required to change the fuel pumping amount from the pump by an amount corresponding to the sum dQILS + dQPL.
QPL) and the feedforward amount T
FBSE is increased by f (dQILS + dQPL). As described above, in the present embodiment, TF (= TFBSE)
When the value of (−TFD + TFBK) increases, the closing timing of the suction valve 5a is delayed, and the amount of fuel pumped from the fuel pump decreases, whereby the amount of fuel pumped from the fuel injection pump 5 decreases by an amount corresponding to dQILS + dQPL. , The corrected TFBSE value is a value corresponding to the static leak amount under the actual fuel injection pump operating conditions. Therefore, by controlling the fuel injection pump 5 using the corrected feedforward amount TFBSE, the fuel pressure in the common rail 3 can be controlled to a value sufficiently close to the target fuel pressure PFIN in a short time.

FIG. 2 is a flow chart for explaining the operation of controlling the fuel pumping amount from the fuel pump. This operation is EC
This is performed as a routine executed by the U20 at regular intervals. In this operation, the ECU 20 determines RO RO based on the common rail target pressure PFIN and the fuel injection command value TAU.
From the numerical table built into M, the feedforward amount T
FBSE is read, and deviations ΔQILS and ΔQ of the static leak amount between the fuel injection valve and the fuel pump from the engine speed NE, the fuel temperature TF, and the common rail target pressure PFIN.
And PL. Then, by an amount corresponding to this deviation, T
The FBSE is increased and the TFBSE after the correction is corrected.
Is used to change the valve closing timing TF of the suction valve 5a to TF = T.
Set as FBSE-TFD + TFBK.

The flowchart of FIG. 2 will be briefly described below. In step 201 of FIG.
5. Accelerator opening (load) ACC detected at 5 and engine speed NE, fuel pressure PC in common rail 3 detected by fuel pressure sensor 31, fuel temperature TF detected by fuel temperature sensor 33, voltage sensor (not shown) The detected battery voltage VB is read. In step 203, the target common rail pressure PFIN and the fuel injection command value TAU calculated based on the engine speed NE and the engine load ACC are read by a routine (not shown) separately executed by the ECU 20.

Further, in step 205, an advance amount TFD for delay time correction is calculated from the battery voltage VB and the engine speed NE based on a predetermined relationship, and step 20 is performed.
In step 7, the feedforward amount TFBSE is determined from the numerical table stored in the ROM in advance by using the common rail target pressure PFIN and the fuel injection amount command value TAU.

Steps 209 to 215 show the calculation of the feedback amount TFBK. That is, step 209
Then, the deviation ΔPC between the target pressure PFIN and the actual common rail pressure PC is calculated as ΔPC = PC−PFIN. In step 211, the integral term BKI is calculated based on ΔPC.
Is calculated. In the present embodiment, the integral term BKI is ΔPC
Is set as follows based on the value of

When ΔPC <−ΔP ₁ , BKI = 0, when ΔΔP ₁ ≦ ΔPC <0, BKI = BKI _i−1
When _{-ΔI 0 ΔPC = 0, BKI =} BKI i-1 0 < When _{ΔPC ≦ ΔP 1, BKI = BKI} i-1 +
BKI = 0 when ΔI ₀ ΔP ₁ <ΔPC That is, in this embodiment, | ΔPC | ≧ ΔP ₁ (ΔP
₍₁ ) is a positive constant value, since the deviation is large in (), the deviation is converged only by the proportional term, and the integral term BKI is relatively small due to variations in the characteristics of the fuel injection pump and the fuel injection valve. Used only for correction of small steady-state deviations. When the deviation ΔPC is negative, the actual common rail pressure is lower than the target pressure. Therefore, in order to increase the fuel pumping amount, the value of BKI is set to the value at the time of the previous execution of the routine BKI.
It is reduced by a fixed amount ΔI ₀ from _i−1 (). Similarly, when the deviation ΔPC is positive, the value of BKI is increased by a fixed amount ΔI ₀ , and the fuel pumping amount is reduced. ΔPC = 0
In this case, the value of BKI is not changed and is kept at the value BKI _i-1 at the time of the previous execution of the routine.

After setting the integral term BKI as described above, in step 213, the value of the proportional term BKP is calculated as BKP = α × ΔPC
(Α is a constant), and in step 215, the feedback amount TFBK is set as TFBK = BKP + BKI. Steps 217 to 221 show an operation of correcting the feedforward amount TFBSE by the static leak amount. In these operations, first, the engine speed NE, the common rail target pressure PFIN,
Actual static leak amount and TFBS based on fuel temperature TF
Deviation ΔQIL from static leak amount included in map of E
S and ΔQPL are calculated (step 217), and TFBS is calculated from the total amount of the deviation (ΔQILS + ΔQPL).
The correction amount f of E (ΔQILS + ΔQPL) is calculated (step 219). In step 221, the value of TFBSE read from the map in step 207 is increased and corrected by the correction amount f (ΔQILS + ΔQPL), and the corrected feedforward amount TFBSE ′ is set to TFBSE ′ = TFB.
It is calculated as SE + f (ΔQILS + ΔQPL).

In step 223, the fuel feed amount of the fuel injection pump 5 (timing of closing the intake valve 5a) using the corrected feedforward amount TFBSE ', the delay time advance amount TFD, and the feedback amount TFBK. TF is calculated as TF = TFBSE'-TFD + TFBK. As described above, in the present embodiment, by the operation of FIG. 2, the EC is determined according to the static leak amount from the fuel injection valve and the fuel injection pump under the actual operating conditions of the fuel pump.
Feedforward amount T read from U20 ROM
Since the FBSE is corrected, the feedforward amount TFBSE is set to an appropriate value even when the pump operation conditions such as the pump speed and the fuel temperature change. For this reason, even when the pump speed or the fuel temperature changes, the fuel pressure in the common rail 3 is controlled with a good response to the target fuel pressure.

[0045]

According to the present invention, the fuel pressure in the accumulator can be controlled with high accuracy and responsiveness even when the operation state of the fuel injection pump such as the rotation speed of the fuel injection pump or the fuel temperature changes. A common effect is achieved in that the target pressure can be well controlled.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a schematic configuration of an embodiment of a fuel injection device of the present invention.

FIG. 2 is a flowchart illustrating an operation of controlling a fuel pressure delivery amount from a fuel injection pump according to the embodiment of FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Fuel injection valve 3 ... Accumulation chamber (common rail) 5 ... Fuel injection pump 10 ... Internal combustion engine 20 ... Control circuit (ECU) 31 ... Fuel pressure sensor 33 ... Fuel temperature sensor

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI // F02M 47/02 F02M 47/02

Claims (4)

[Claims] An accumulator for storing pressurized fuel, a fuel injection valve for injecting fuel in the accumulator into an internal combustion engine, a fuel injection pump for supplying fuel to the accumulator, and a fuel pressure in the accumulator. A control means for setting a target value of the amount of fuel supplied from the fuel injection pump to the accumulator so that the fuel pressure becomes a predetermined target pressure. Operating state detecting means for detecting an operating state of the pump; leaked fuel not contributing to an increase in the pressure of the accumulator chamber, of the fuel pumped from the fuel injection pump based on the pump operating state detected by the operating state detecting means An accumulator-type fuel injection device comprising: a leak fuel amount calculating unit that calculates the amount of the fuel; and a correcting unit that corrects the fuel amount target value according to the calculated leak fuel amount. 2. The accumulator according to claim 1, wherein the leak fuel amount is an amount of static leak fuel generated from the fuel injection valve and the fuel injection pump regardless of whether or not the fuel injection valve performs a fuel injection operation. Type fuel injection device. 3. The accumulator type fuel injection device according to claim 1, wherein the leaked fuel calculating means calculates the leaked fuel amount based on a fuel injection pump rotation speed and a fuel temperature. 4. The fuel amount target value is determined by a feedforward amount determined by the target pressure of the accumulator and a fuel injection amount from a fuel injection valve, and a deviation between an actual fuel pressure in the accumulator and the target pressure. The accumulator-type fuel injection device according to claim 1, wherein the amount is set as an amount including a determined feedback amount, and the correction unit corrects the feedforward amount.