JPH04272446A - Pressure accumulation type fuel injection device of diesel engine - Google Patents

Abstract

PURPOSE:To maintain good exhaust gas characteristic even at a transient likely occurring at sudden change of the operating conditions, and prevent increase of smokes at accelerating and also NOx increase and noise generation at deceleration. CONSTITUTION:In a fuel injection control device of common rail type, the actual common rail pressure PC is compared with the target common rail pressure PFIN (S6), and if PC<PFIN-alpha, a correction is executed so as to reduce the target fuel injection amount QFIN (S7). As a result, the fuel with a lower pressure than the target value will never injected in any large quantity, which should prevent generation of smokes. If PC>PFIN+beta, the target fuel injection timing is delayed to suppress violent combustion, and noise generation and NOx increase are prevented.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is a diesel engine that calculates fuel injection conditions such as target fuel injection amount and target fuel injection timing according to operating conditions, and injects high-pressure fuel temporarily stored in a pressure accumulator according to these fuel injection conditions. This invention relates to an accumulator fuel injection device for an engine.

0002

[Prior Art] Conventionally, as described in Japanese Patent Publication No. 60-60020, in a common rail unit injector, the common rail pressure is controlled to a target value according to operating conditions, and fuel injection is performed according to the operating conditions. It was configured to perform fuel injection corresponding to the operating conditions by calculating the amount and fuel injection timing and controlling the opening of the injector that injects fuel from the pressure accumulation chamber.

0003

[Problem to be solved by the invention] In normal operating conditions,
Since the common rail pressure is maintained at a target value depending on the operating conditions, fuel injection to the engine is dependent on the operating conditions.

[0004] However, even though the target value of the common rail pressure increases rapidly during acceleration or when the load increases,
The actual rise in common rail pressure is delayed. It is extremely difficult to mechanically eliminate this response delay.

On the other hand, during sudden acceleration, for example, it is necessary to significantly increase the fuel injection amount, so the target fuel injection amount increases. As a result, during such rapid acceleration, a large amount of fuel is injected at a pressure lower than the target value, resulting in a problem of deterioration of exhaust gas performance such as an increase in smoke and an increase in CO gas.

[0006] Furthermore, if there is a change in operating conditions such as sudden deceleration from high speed running, the common rail pressure will conversely remain higher than the target value. In such a situation,
Since the fuel is easily atomized, the ignition timing becomes early, which causes noise, increases NOx, and deteriorates exhaust gas performance.

[0007] The present invention can maintain good exhaust gas performance even during such transient times as seen in sudden changes in operating conditions, and reduces the increase in smoke during acceleration and NO during deceleration.
It was completed with the aim of providing a pressure accumulation type fuel injection device for diesel engines that can prevent an increase in X and the generation of noise.

[0008]

[Means for Solving the Problems and Effects] In order to achieve the above object, the present invention provides a pressure accumulating chamber for temporarily storing fuel to be supplied to a diesel engine in a high pressure state, and a fuel accumulating chamber for pumping the fuel to the accumulating chamber. a pressure-feeding means, a pressure detection means for detecting the fuel pressure in the pressure accumulation chamber, an operating condition detection means for detecting the operating condition of the diesel engine, and a pressure detection means for detecting the fuel pressure in the pressure accumulation chamber based on the operating condition detected by the operating condition detection means. A target pressure calculating means for calculating a target value of fuel pressure, and comparing the target value with a value detected by the pressure detecting means, and driving the fuel pressure feeding means so as to set the fuel pressure in the pressure accumulation chamber to the target value. a feedback control means for controlling; a fuel injection amount calculation means for calculating a target fuel injection amount to the diesel engine based on the operating conditions detected by the operating condition detection means; In the pressure accumulation type fuel injection device for a diesel engine, which includes fuel injection means for injecting high pressure fuel stored in the pressure accumulation chamber to the diesel engine, whether the detected value of the pressure accumulation chamber pressure is lower than a target value by a predetermined value or more. and a correction means for correcting the calculated target fuel injection amount to a smaller value when the judgment means judges that the detected value of the pressure accumulator pressure is lower than the target value by a predetermined value or more. It is characterized by having the following.

As a result of adopting this configuration, when the fuel pressure in the pressure accumulation chamber is lower than the target value by more than a predetermined value due to a response delay, such as during sudden acceleration, the fuel injection amount is corrected to a smaller value. A large amount of fuel with a pressure lower than that is not injected. As a result, smoke and CO
Gas generation can be suppressed and deterioration of exhaust gas performance can be prevented.

On the other hand, as a countermeasure against sudden deceleration, the present invention also provides a pressure accumulator for temporarily storing fuel to be supplied to the diesel engine in a high pressure state, and a fuel pumping system for pressurizing the fuel to the pressure accumulator. pressure detection means for detecting the fuel pressure in the pressure accumulation chamber; operating condition detection means for detecting the operating conditions of the diesel engine; and a pressure detection means for detecting the fuel pressure in the pressure accumulation chamber; A target pressure calculating means for calculating a target value of pressure, and comparing the target value with a value detected by the pressure detecting means, and driving and controlling the fuel pumping means so that the fuel pressure in the pressure accumulator reaches the target value. feedback control means for calculating the target fuel injection timing for the diesel engine based on the operating conditions detected by the operating condition detection means; In a pressure accumulation type fuel injection device for a diesel engine, which includes a fuel injection means for injecting high pressure fuel stored in a pressure accumulation chamber into a diesel engine, it is determined whether a detected value of the pressure accumulation chamber pressure is higher than a target value by a predetermined value or more. and a correction means for correcting to delay the calculated target fuel injection timing when the judgment means judges that the detected value of the pressure accumulator pressure is higher than the target value by a predetermined value or more. The present invention has also invented an accumulator fuel injection device for a diesel engine according to claim 2, characterized in that:

According to this configuration, the ignition timing is prevented from advancing by delaying the injection timing of the fuel that is easily atomized at a predetermined higher pressure than the target, thereby preventing the generation of NOx and reducing noise during sudden deceleration. can be achieved.

0012

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be explained in detail with reference to embodiments shown in the drawings. FIG. 1 is an explanatory diagram of the configuration of a common rail fuel injection control device including a variable discharge amount high pressure pump.

This common rail type fuel injection control device 1 includes a six-cylinder diesel engine 2, an injector 3 for injecting fuel into each cylinder of the diesel engine 2, and a common rail 4 for accumulating high-pressure fuel to be supplied to the injector 3. , a variable discharge amount high-pressure pump 5 that pumps high-pressure fuel to the common rail 4, and an electronic control device (
ECU) 6.

The ECU 6 takes in operating conditions such as the state of the diesel engine 2, such as the detected value of the rotation speed sensor 7 and the detected value of the accelerator sensor 8, and controls the diesel engine 2.
A target common rail pressure PFIN is calculated to achieve a fuel injection pressure that optimizes the combustion state of
Common rail pressure feedback control is performed to drive and control the variable discharge amount high pressure pump 5 so as to maintain the same.

The variable discharge amount high pressure pump 5 sucks the fuel stored in the fuel tank 10 via the low pressure supply pump 11 in accordance with the control command from the ECU, pressurizes it to a high pressure inside itself, and this pressurization. Pipe 12 for supplying high-pressure fuel
It is force-fed to the common rail 4 via.

Each injector 3 is connected by a pipe 13 to
It is connected to a common rail 4 that stores high-pressure fuel. By opening and closing the control valve 14 disposed in each injector 3, the high-pressure fuel accumulated in the common rail 4 and reaching the target common rail pressure PFIN is injected into the combustion chamber of each cylinder of the diesel engine 2. be done. The opening/closing operation of the control valve 14 of the injector 3 is executed based on an injector control command from the ECU 6. This injector control command is for adjusting the fuel injection amount and fuel injection timing, and is calculated based on the detected values from operating condition detection means such as the rotation speed sensor 7 and the accelerator sensor 8. It is outputted from the ECU 6 at a predetermined timing based on the detected values of the cylinder discrimination sensor 16 and the like. Note that control commands for the variable discharge amount high pressure pump 5 are also output at predetermined timings based on detected values from the crank angle sensor 15, a cam angle sensor 38, etc. to be described later.

Next, the configuration of the variable discharge amount high pressure pump 5 will be explained based on FIGS. 2 and 3. Variable discharge amount high pressure pump 5
communicates with the housing 20, a cam chamber 30 disposed at its lower end, a pump cylinder 21 disposed within the housing 20, and supplies low-pressure fuel from the low-pressure supply pump 11. It includes an introduction pipe 22 for receiving the pump cylinder 21, and a solenoid valve 60 screwed onto the upper end of the pump cylinder 21.

A plunger 23 is slidably inserted into the pump cylinder 21 in a fluid-tight manner. The plunger 23 has a cylindrical shape, and its upper end surface cooperates with the inner peripheral surface of the pump cylinder 21 to form a pump chamber 24 . The pump cylinder 21 has a supply pipe 1 to the common rail 4.
A discharge hole 41 to which the two are connected is bored.

Furthermore, the pump cylinder 21 and the housing 2
A fuel reservoir 26 is formed between the housing 20 and the low-pressure fuel introduced from the introduction pipe 22 into the housing 20. Note that the fuel reservoir 26 also acts as a release for fuel overflowing from the pump chamber 24.

The discharge hole 41 communicates with a discharge port 45 via a check valve 42. The fuel pressurized in the pump chamber 24 pushes the valve body 43 of the check valve 42 through the return spring 4.
By pushing open against the urging force of 4 and common rail pressure,
It passes through the supply pipe 12 from the discharge port 45 and is fed under pressure to the common rail 4.

The lower end of the plunger 23 is connected to a valve seat 35, which is pressed by a plunger spring 27 against a tappet 34 having a cam roller 33. Inside the cam chamber 30, a rotation speed of 1 of the rotation speed of the diesel engine 2 is stored.
A camshaft 31 that rotates at a speed of /2 is inserted through the camshaft 31, and a cam 32 that contacts a cam roller 33 is fixed to the camshaft 31. The rotation of the camshaft 31 causes the plunger 23 to reciprocate up and down along the cam profile of the cam 32 via the cam roller 33 and tappet 34.

If the bottom dead center of the plunger 23 of the cam profile is set to a cam angle of 0 degrees, the cam 32 has a circular arc shape with a curvature R1 centered outside the cam 32 from a cam angle of 0 degrees to approximately 30 degrees. It has a substantially elliptical shape and has a cam profile such that the plunger 23 reaches the top dead center at a cam angle of 90 degrees.

The solenoid valve 60 screwed onto the upper end of the pump cylinder 21 includes a valve body 62 that opens and closes a low pressure passage 61 opening into the pump chamber 24 . The valve body 62 is a so-called outward-opening valve. Therefore, the valve body 62 normally has a spring 6
5 opens into the pump chamber 24 and opens the low pressure passage 61, and when energized, the spring 6
5, the low pressure passage 61 and the pump chamber 2
4 will be cut off. Further, since the valve body 62 receives the fuel pressure inside the pump chamber 24 as pressure in the valve closing direction, the higher the fuel pressure, the better the sealing performance when the valve is closed.

The low pressure passage 61, which is opened and closed by the valve body 62, communicates with the fuel reservoir 26 via a gallery 63 and a passage 64. On the other hand, the plunger 23 moves up and down within the pump cylinder 21 as the camshaft 31 rotates. Note that the plunger 23 is lowered by the return force of the plunger spring 27.

When the plunger 23 descends, low pressure fuel flows into the fuel reservoir 26 via the solenoid valve 60 which is normally open.
and is sucked into the pump chamber 24. The fuel sucked into the pump chamber 24 tends to be pressurized as the plunger 23 rises, but if the solenoid valve 60 is not energized, it passes through the low pressure passage 61, the gallery 63, and the passage 64 to the fuel reservoir 26. No substantial pressurization of the fuel within the pump chamber 24 occurs.

On the other hand, if the electromagnetic valve 60 is energized while the plunger 23 is rising, the valve body 62 will close to the low pressure passage 61.
As a result, the fuel in the pump chamber 24 is no longer able to overflow and begins to be pressurized. And pump room 2
When the fuel pressure inside the check valve 4 rises and overcomes the biasing force of the return spring 44 of the check valve 42 and the pressure of the common rail 4 applied to the valve body 43, the check valve 42 is pushed open and high-pressure fuel is discharged. Hole 41, discharge port 45 and supply piping 1
2 to the common rail 4.

As shown in FIG. 3, the camshaft 31 is equipped with one timing gear 36 and variable discharge amount high pressure pumps 5 (in this embodiment, three
) are arranged. In addition, for convenience, one of the variable discharge amount high pressure pumps is omitted in the figure, and only two variable discharge amount high pressure pumps 5a and 5b are shown. Also, the same configurations as shown in FIG. 2 are given subscripts a and b, respectively, so please refer to FIG. 2 for the detailed structure of the configurations with the subscripts a and b.

A total of six protrusions 37 are provided on the timing gear 36. Further, a cam angle sensor 38 consisting of an electromagnetic pickup is provided in close opposition to the timing gear 36 .

[0029]Protrusion 37 provided on timing gear 36
is each cam 32a, 32b during one rotation of the camshaft 31
,... for the cam angle sensor 38 to detect the start timing of the upward stroke of the plungers 23a, 23b,... executed by each high-pressure pump 5a, 5b,... (i.e., bottom dead center arrival timing). It is something. A timing signal detected by this cam angle sensor 38 is input to the ECU 6.

The ECU 6 operates the solenoid valves 60a, 60b, . . . based on the timing signal from the cam angle sensor 38.
Outputs drive pulses to. As shown in FIG. 4, this drive pulse is output with a delay of a period TF (hereinafter referred to as output waiting period TF) with respect to the timing signal detected at the bottom dead center position of the plunger 23 as a reference pulse. This drive pulse starts energizing the solenoid valve 60, and the valve body 62 is closed with a delay of a period TC (hereinafter referred to as valve closing delay TC) due to the rise of the current. Thereafter, the valve body 62 is maintained in a closed state by the pressure increase in the pump chamber 24 as the plunger 23 rises, so the drive pulse is turned off after a short period of time TON has elapsed, thereby saving power consumption. . This is an advantage of an outward-opening valve.

The period from when the valve body 62 closes to when the plunger 23 reaches the top dead center is the period during which fuel is pressurized within the pump chamber 24, and an amount of fuel proportional to the area of the hatched portion in the figure is supplied to the common rail. It will be pumped to 4. Therefore, in this figure, if the output timing of the drive pulse is made earlier so that the hatched area becomes larger, more fuel will be pumped to the common rail 4, and conversely, if the output timing is delayed, the amount of fuel pumped to the common rail 4 will be reduced. Decrease. In other words, the pressure of the common rail 4 can be adjusted by the output timing of the drive pulse (output waiting period TF).

Next, a main routine for feedback controlling the pressure of the common rail 4 will be explained. E
As shown in FIG. 5, the CU 6 calculates the engine rotation speed Ne based on the detected value of the rotation speed sensor 7 (S1), and converts the detected value of the accelerator sensor 8 from A/D to determine the accelerator opening degree A.
Find ccp (S2).

Next, based on these engine speed Ne and accelerator opening Accp, the target fuel injection amount QFIN is calculated with reference to a target fuel injection amount calculation map as shown in FIG.
is calculated (S3). And this target fuel injection amount QF
Based on IN and engine speed Ne, target common rail pressure PFIN is calculated with reference to a target common rail pressure calculation map as shown in FIG. 7 (S4). Note that each map is stored in the built-in ROM of the ECU 6, and the calculation results QFIN, PFIN, etc. are stored in the built-in RAM.

Next, the detected value of the common rail pressure sensor 9 is A/D converted to calculate the actual common rail pressure PC (S
5). Then, it is determined whether the actual common rail pressure PC is lower than the target common rail pressure PFIN by more than a predetermined value α (S6). This predetermined value α is determined based on the amount by which the actual common rail pressure PC becomes lower than the target common rail pressure PFIN due to responsiveness during sudden acceleration, etc., and is used to judge whether or not a response delay has occurred. This is a reference value.

[0035] If this judgment is ``YES'', the actual common rail pressure PC is considerably lower than the target common rail pressure PFIN due to the response delay, so fuel injection according to the target fuel injection amount QFIN is performed as is. Then, fuel with a lower pressure than planned is injected into the combustion chamber, and if this continues, problems such as smoke generation will occur.

Therefore, in such a case, the ratio PC/PFIN of the actual common rail pressure PC and the target common rail pressure PFIN
The value obtained by multiplying the target fuel injection amount QFIN obtained in the process of S3 by the function f (PC/PFIN) with the parameter as
A new target fuel injection amount QFIN' is set (S7). Note that the function f(PC/PFIN) has a function value of 1.0 or less, and the smaller the parameter PC/PFIN, the smaller the value.

Therefore, when the actual common rail pressure PC is lower than the target common rail pressure PFIN by more than the predetermined value α, the target fuel injection amount is corrected to a smaller value. Thereafter, the process proceeds to step S8, where fuel injection timing is calculated from the corrected target fuel injection amount QFIN' and the actual common rail pressure PC, and fuel injection control is executed. Also, based on the target common rail pressure PFIN and the corrected target fuel injection amount QFIN', refer to a drive pulse output waiting period calculation map as shown in FIG. Period) TFBAS
E is calculated (S9), the target common rail pressure PFIN and the actual common rail pressure PC are compared, and the pressure difference ΔP=P
A correction amount TFFB for the reference output waiting period TFBASE is calculated according to C-PFIN (S10). In calculating this correction amount TFFB, the generally well-known PI
A method of D control is used.

Next, an output waiting period TF for control is calculated as the sum of the reference output waiting period TFBASE and the correction amount TFFB (S11), and each electromagnetic valve 60a, 60b, . . . is driven according to this output waiting period TF. Feedback control (S12) is executed to maintain the pressure in the common rail 4 at a target common rail pressure PFIN suitable for performing fuel injection according to operating conditions such as engine speed Ne and accelerator opening Accp.

On the other hand, if the determination in S6 is "NO", as a result, the target fuel injection amount QFIN is not corrected and the process directly proceeds from S8 onwards (S1
3).

The operation and effect of this embodiment will be explained with reference to the timing chart of FIG. 9 when a stopped vehicle suddenly starts. Accelerator opening Accp at time T1
When QFIN rapidly increases, the target fuel injection amount QFIN as a map instruction value also increases rapidly. Therefore, the target common rail pressure PFIN as the map instruction value also becomes a condition for increasing. However, the engine speed Ne does not rise as suddenly as the accelerator opening Accp, but rises slowly. In this transient state where the engine speed Ne does not become sufficiently large, the actual common rail pressure P
C becomes lower than the target common rail pressure PFIN. Therefore, if fuel injection is carried out without any countermeasures, a large amount of low-pressure fuel will be injected, deterioration of combustion, etc. will occur, and a large amount of smoke will be generated as shown by hatching in the figure.

However, in this embodiment, during this transient state, fuel injection is performed at the target fuel injection amount QFIN' which is corrected to a smaller value than the map instruction value QFIN.
Such deterioration of combustion is not caused, and the generation of smoke can be minimized.

[0042] Then, as after time T2, when the difference between the target common rail pressure PFIN and the actual common rail pressure PC shifts to a steady state where it is smaller than the predetermined value α, the target fuel injection amount QFIN' = QFIN according to the map instruction value. Fuel injection is performed at , and stable operating conditions are achieved.

Note that the map instruction value Q of the target fuel injection amount
Since FIN is corrected and becomes smaller, and the amount of fuel supplied from the common rail 4 to the injector 3 is suppressed,
In addition to suppressing the occurrence of smoke, feedback control also has the effect of quickly approaching the target common rail pressure PFIN.

Next, a second embodiment will be explained. The second embodiment has the same hardware configuration as the first embodiment, but the main routine for feedback controlling the pressure of the common rail 4 is as shown in FIG.

[0045] Also in the main routine of the second embodiment,
The ECU 6 calculates the engine rotation speed Ne (S21),
Calculate the accelerator opening Accp (S22), calculate the target fuel injection amount QFIN (S23), and calculate the target common rail pressure P.
While calculating FIN (S24), the target fuel injection timing TFIN is calculated (S25). Furthermore, the actual common rail pressure PC is calculated (S26). Furthermore, the target fuel injection amount Q
In calculating FIN, etc., the same method as in the first embodiment is adopted. In addition, the target fuel injection amount TFIN is calculated using a general method that is normally used.
Detailed explanation will be omitted.

Next, it is determined whether the actual common rail pressure PC is higher than the target common rail pressure PFIN by more than a predetermined value β (S27). This predetermined value β is determined based on the amount by which the actual common rail pressure PC exceeds the target common rail pressure PFIN due to responsiveness during sudden deceleration, etc., and is used to determine whether a response delay has occurred. This is a reference value.

If this judgment is ``YES'', the actual common rail pressure PC is considerably higher than the target common rail pressure PFIN due to the response delay, so if fuel injection is performed as it is, the pressure will be higher than planned. Since fuel that easily atomizes is injected into the combustion chamber, the combustion temperature becomes too high, causing noise and N
The problem of generation of OX arises.

Therefore, in such a case, the ratio PC/PFIN of the actual common rail pressure PC and the target common rail pressure PFIN
Function g(PC/PFIN) with parameter is S24
The value added to the target fuel injection timing TFIN obtained in the process is set as a new target fuel injection timing TFIN' (S28
). Note that the function g (PC/PFIN) is the parameter PC
The smaller the /PFIN, the smaller the function, that is,
This is a function in which the smaller the parameter PC/PFIN is, the smaller the retardation correction amount becomes.

Therefore, when the actual common rail pressure PC is higher than the target common rail pressure PFIN by more than the predetermined value β, the target fuel injection timing is retarded. Thereafter, fuel injection control is executed according to the corrected target fuel injection timing TFIN' (S29), and based on the target common rail pressure PFIN and target fuel injection amount QFIN, the reference output waiting period TFBASE and its A correction amount TFFB is calculated (S30, S31), and feedback control is executed in the direction of maintaining the actual common rail pressure PC at the target common rail pressure PFIN according to the control output waiting period TF, which is the sum of both (S32, S33).
).

On the other hand, if the determination in S27 is "YES", the result is that the target fuel injection timing TFI
The process directly proceeds to S29 and subsequent steps without performing the correction of N (S34).

According to this second embodiment, during sudden deceleration, the fuel supplied from the common rail 4 is high-pressure and tends to atomize, but by retarding the injection timing, the occurrence of intense combustion is suppressed and noise is reduced. It is possible to suppress the generation of NOx as well as suppress the generation of NOx.

Although the embodiments of the present invention have been described above, the present invention is not limited thereto, and various embodiments can be adopted without departing from the gist thereof. For example, in the main routine of the second embodiment, "NO" is selected in the process of S27.
If so, a modification may be made that satisfies both the first and second embodiments, such as executing the processing from S6 onwards in the main routine of the first embodiment.

Furthermore, in the first embodiment, when the predetermined value α is set to a large value, the current target fuel injection amount QFIN' is i and the previous target fuel injection amount QFIN'i-1, QFIN' = 1/2 (QFIN'i + QFIN'i
-1), etc., it is possible to eliminate discontinuity in control at the time of switching.

Furthermore, in the embodiment, the transient period when a large amount of smoke is generated is judged based on the difference between the actual common rail pressure PC and the target common rail pressure PFIN, but the transient period can be determined by a sudden change in the accelerator opening Accp, etc. You can judge. However, as in the embodiment, it is more direct and better to monitor the difference in common rail pressure, which is the cause of smoke generation.

In addition, in correcting the target fuel injection amount,
In the example, the function f(PC/PFIN) is smaller than 1.0.
Although the configuration has been described in which the values are multiplied, a configuration in which a predetermined numerical value is subtracted may also be used.

[0056]

As described above, according to the invention as set forth in claim 1, it is possible to suppress the increase in smoke and CO during sudden acceleration, and achieve good exhaust gas performance. Further, by reducing the target fuel injection amount, the amount of fuel supplied from the pressure accumulation means to the fuel injection means can be reduced, and the delay in controlling the fuel pressure can be quickly eliminated.

On the other hand, according to the second aspect of the invention, it is possible to prevent an increase in NOx and generation of noise during sudden deceleration.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing a system of an embodiment.

FIG. 2 is a sectional view showing the configuration of a variable discharge amount high pressure pump.

FIG. 3 is a schematic diagram illustrating the configuration of a variable discharge amount high-pressure pump.

FIG. 4 is a timing chart illustrating the operation of the variable discharge amount high pressure pump.

FIG. 5 is a flowchart of the main routine of fuel injection control executed by the ECU in the first embodiment.

FIG. 6 is a map for calculating target fuel injection amount.

FIG. 7 is a map for calculating target common rail pressure.

FIG. 8 is a map for calculating the standard output waiting period.

FIG. 9 is a timing chart showing a control state during sudden acceleration in the first embodiment.

FIG. 10 is a flowchart of a main routine of fuel injection control performed by the ECU in the second embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1... Common rail fuel injection control device, 2... Diesel engine, 3... Injector, 4... Common rail, 5... Variable discharge amount high pressure pump, 6...
Electronic control unit (ECU), 7... rotation speed sensor, 8.
... Accelerator sensor, 9... Common rail pressure sensor,
10...Fuel tank, 11...Low pressure supply pump, 1
2... Supply piping, 13... Piping, 14... Control valve, 15... Crank angle sensor, 16... Cylinder discrimination sensor, 23... Plunger, 24... Pump chamber, 26 ...Fuel reservoir, 32...Cam, 38...
Cam angle sensor, 42... Check valve, 45... Discharge port, 60... Solenoid valve, 61... Low pressure passage, 62...
Valve body.

Claims (2)

[Claims] 1. A pressure accumulation chamber for temporarily storing fuel to be supplied to a diesel engine in a high pressure state, a fuel pressure-feeding means for force-feeding the fuel to the pressure accumulation chamber, and a pressure detection means for detecting the fuel pressure in the pressure accumulation chamber. an operating condition detecting means for detecting operating conditions of the diesel engine; a target pressure calculating means for calculating a target value of fuel pressure in the pressure accumulator based on the operating conditions detected by the operating condition detecting means; a feedback control means for driving and controlling the fuel pressure feeding means so as to set the fuel pressure in the pressure accumulation chamber to the target value by comparing a value detected by the pressure detection means; and an operating condition detected by the operating condition detection means. a fuel injection amount calculation unit that calculates a target fuel injection amount to the diesel engine based on the calculated target fuel injection amount; and a fuel injection unit that injects the high pressure fuel stored in the pressure accumulation chamber to the diesel engine based on the calculated target fuel injection amount. a pressure accumulator fuel injection device for a diesel engine, comprising: a determining means for determining whether the detected value of the pressure accumulator pressure is lower than a target value by a predetermined value or more; A pressure accumulation type fuel injection device for a diesel engine, comprising: a correction means for correcting the calculated target fuel injection amount to a smaller value when it is determined that the amount is lower than the target value by a predetermined value or more. 2. A pressure accumulator for temporarily storing fuel to be supplied to a diesel engine in a high pressure state, a fuel pressure-feeding means for force-feeding the fuel to the pressure accumulator, and a pressure detection means for detecting the fuel pressure in the pressure accumulator; an operating condition detecting means for detecting operating conditions of the diesel engine; a target pressure calculating means for calculating a target value of fuel pressure in the pressure accumulator based on the operating conditions detected by the operating condition detecting means; a feedback control means for driving and controlling the fuel pressure feeding means so as to set the fuel pressure in the pressure accumulation chamber to the target value by comparing a value detected by the pressure detection means; and an operating condition detected by the operating condition detection means. a fuel injection timing calculation means for calculating a target fuel injection timing to the diesel engine based on;
and a fuel injection device for injecting high pressure fuel stored in the pressure accumulation chamber to the diesel engine based on the calculated target fuel injection timing, the detected value of the pressure accumulation chamber pressure. is higher than the target value by a predetermined value or more; 1. A pressure accumulation type fuel injection device for a diesel engine, comprising a correction means for correcting to delay injection timing.