JP3360336B2 - Fuel injection device for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection device for a pressure-accumulation type internal combustion engine, and more particularly to a fuel injection device for rapidly increasing the fuel pressure in a pressure accumulator at the time of starting.

[0002]

2. Description of the Related Art Conventionally, in a diesel engine vehicle equipped with a common rail type unit injector, a variable discharge high pressure pump for controlling a common rail pressure, for example, one described in Japanese Patent Application Laid-Open No. 2-146256 is known. I was When the plunger fitted in the plunger chamber rises, such a variable discharge high pressure pump closes an externally opened solenoid valve attached to the plunger chamber to increase the internal pressure of the plunger chamber, thereby increasing the pressure between the plunger chamber and the common rail. Was opened and the fuel oil was pumped.

[0003] By the way, as described in this publication,
At the start of the engine, the common rail pressure was reduced, so it was necessary to take measures to rapidly increase the common rail pressure. For this reason, conventionally, as shown in FIG. 16, start-up control in which the solenoid valve is closed for a predetermined valve-closing period T <b> 1 and subsequently opened for a short valve-opening period T <b> 2 has been adopted.

[0004] With this control, the fuel oil can be pumped over each period of T1 while the plunger is raised, and the fuel is sucked for each period of T2 while the plunger is lowered. Was. Then, the starting control is continued until the common rail pressure becomes equal to or higher than a predetermined value or the engine speed becomes equal to or higher than a predetermined value.

[0005]

The above-mentioned valve closing period T1 is:
It is desirable to consider the period during which the internal pressure of the plunger chamber can be raised to the pressure at which the externally opened solenoid valve self-closes due to the plunger rise.However, since the starting time is transient, the engine condition is stable. However, due to engine differences between the engines and aging, a situation in which the plunger opens during the rise of the plunger as shown in FIG. It was not done. Also, due to the opening of the valve during the rise of the plunger, the [plunger chamber pressure] once increased before that may decrease again, and the fuel pumping amount is smaller than the ideal case indicated by the dotted line. Not so much.

On the other hand, the valve opening period T2 is desirably determined in consideration of a period during which a sufficient amount of fuel oil can be sucked into the plunger chamber while the plunger is lowered.
It is difficult to determine this accurately, and sometimes the period is too short and the intake of fuel oil becomes insufficient. If the intake of the fuel oil is insufficient, the pumping amount of the fuel oil when the plunger rises next will decrease.

As described above, in the conventional control method at the time of starting, there is a problem that waste and excessive force are generated in both the fuel feeding and the fuel suction, and the rise of the common rail pressure at the time of starting cannot be accelerated so much. Accordingly, it is an object of the present invention to provide a fuel injection device that eliminates the above-mentioned waste and unreasonability and can increase the common rail pressure more quickly at the time of starting.

[0008]

According to the first aspect of the present invention, a plunger is opened and closed by opening and closing a control valve in accordance with the movement of a plunger fitted in a plunger chamber. A fuel pumping means for pumping the fuel in the chamber to the accumulator, and a reference signal corresponding to the bottom dead center of the plunger for setting the operation timing of the control valve.
No., a cylinder discrimination sensor for discriminating the cylinder of the internal combustion engine and
At least a speed sensor for detecting the speed of the internal combustion engine
Based on one of the sensor values, a reference signal output means for outputting, a pressure detection means for detecting a fuel pressure in the accumulator, and a value detected by the pressure detector being compared with a target pressure for fuel injection. Feedback control means for setting the operation timing of the control valve based on the reference signal so as to set the fuel pressure to the target pressure, and for driving and controlling the fuel pumping means. In a fuel injection device of an internal combustion engine that injects fuel with fuel,
At the time of starting the internal combustion engine, the opening and closing operation by the control valve is repeated at predetermined time intervals, and a first start-up control for pumping fuel sucked into the plunger chamber to the pressure accumulating chamber is performed.
Subsequently , the reference signal output means outputs the reference signal.
After the output of the control signal is detected , the control valve is closed during the rise of the plunger which is determined from the reference signal by the reference signal output means, and the control valve is opened during the decrease which is also determined. the second start-up time control the real
The start-up control means for rapidly increasing the fuel pressure of the pressure accumulating chamber by performing the control is provided.

According to the first aspect of the invention, after the engine is started , at least one of the cylinder discrimination sensor and the rotation speed sensor is used.
The reference signal corresponding to the bottom dead center of the plunger based on the sensor value
Signal was output from the reference signal output means.
Thereafter , the second start-up control is executed in which the control valve is closed during the rise of the plunger which is found from the reference signal and the control valve is opened during the downward movement which is also found.

In the second start-time control, the control valve is kept closed almost all the time when the plunger is raised.
Fuel oil can be pumped to the accumulator to the maximum extent. Further, while the plunger is lowered, the control valve is kept open almost all the time, so that sufficient fuel oil can be sucked into the plunger chamber. That is, the pumping of the fuel oil to the pressure accumulating chamber is executed over almost the entire period while the plunger is moving up, and the suction of the fuel oil into the plunger chamber is executed over almost the entire period while the plunger is moving down.

Furthermore, since there is no such reference signal is obtained immediately after cranking of the internal combustion engine is common, the while the starting control according to the second start control means can not be executed, the second start control Prior to (for example,
Similarly to as No. -146,256 a) a first start control is real
Will be applied. In the first start-up control, the control valve is opened and closed so as to repeat a predetermined valve-opening period and a predetermined valve-closing period. to. In this way, fuel pumping to the accumulator can be started from the very initial point in time when the reference signal cannot be obtained, and fuel pumping to the accumulator can be started immediately after the engine is started.

[0012]

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

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

The ECU 6 determines the state of the diesel engine 2, for example, the detected value of the rotational speed sensor 7 and the accelerator sensor 8.
And the target common rail pressure PFIN for realizing the fuel injection pressure for optimizing the combustion state of the diesel engine 2 is calculated, and the detection value of the common rail pressure sensor 9 provided on the common rail 4 is obtained. The actual common rail pressure PC based on the target common rail pressure PFI
The common rail pressure feedback control for driving and controlling the variable discharge amount high pressure pump 5 is performed so as to maintain N.

The variable discharge high pressure pump 5 includes an ECU 6
The fuel stored in the fuel tank 10 is sucked through the low-pressure supply pump 11 in accordance with the control command from the fuel tank 10 and pressurized to a high pressure inside itself, and the pressurized high-pressure fuel is supplied to the supply pipe 1.
2 to the common rail 4.

Each injector 3 is connected by a pipe 13
It is connected to a common rail 4 storing high-pressure fuel.
By opening and closing a control valve 14 disposed in each injector 3, high-pressure fuel accumulated in the common rail 4 and having a target common rail pressure PFIN is injected into a combustion chamber of each cylinder of the diesel engine 2. Is done.

The opening and 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 the fuel injection timing, and is based on detection values from operating condition detecting means such as a rotation speed sensor (hereinafter referred to as Ne sensor) 7 and an accelerator sensor 8. It is calculated and output from the ECU 6 at a predetermined timing based on detection values of a cylinder discrimination sensor (hereinafter, referred to as a G sensor) 16 and an idle switch 17. Note that a control command for the variable discharge amount high pressure pump 5 is also output at a predetermined timing based on a detection value from the G sensor 16, the idle switch 17, and the like.

Next, the configuration of the variable discharge high pressure pump 5 will be described with reference to FIGS. Variable discharge high pressure pump 5
Communicates with the housing 20, a cam chamber 30 disposed at the lower end thereof, a pump cylinder 21 disposed within the housing 20, and a pump cylinder 21 to supply the low-pressure fuel from the low-pressure supply pump 11. A receiving pipe 22 and a solenoid valve 60 as a control valve screwed to the upper end of the pump cylinder 21 are provided.

A plunger 23 is slidably fitted inside the pump cylinder 21 while maintaining liquid tightness. The plunger 23 has a cylindrical shape, and an upper end surface thereof forms a pump chamber 24 in cooperation with an inner peripheral surface of the pump cylinder 21. 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 provided.

The pump cylinder 21 and the housing 2
A fuel tank 26 is formed between the fuel tank 26 and the fuel tank 26, and the low-pressure fuel introduced into the housing 20 from the inlet pipe 22 is stored therein. Note that the fuel reservoir 26 also acts as a relief for the 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 open against the urging force of the return spring 44 and the common rail pressure, so that the fuel passes through the supply pipe 12 from the discharge port 45, It is fed to the common rail 4 by pressure.

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

If the bottom dead center of the plunger 23 of the cam profile is 0 degree, the cam 32 has a concave curved surface 32c and a cam profile extending to a top 32d which is the top dead center of the plunger 23 in the cam profile. Cam angle 60
It is a substantially equilateral triangle with degrees.

The solenoid valve 60 screwed to the upper end of the pump cylinder 21 has a valve body 62 for opening and closing a low-pressure passage 61 opening to the pump chamber 24. The valve body 62 is a so-called external valve. Therefore, the valve element 62 is normally
5, the state is opened into the pump chamber 24 to open the low-pressure passage 61.
5 and the low pressure passage 61 and the pump chamber 2
4 is shut off. Further, since the valve element 62 receives the fuel pressure inside the pump chamber 24 as the 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 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 in the pump cylinder 21 as the camshaft 31 rotates. The plunger 23 is lowered by the return force of the plunger spring 27.

When the plunger 23 descends, low-pressure fuel is supplied to the fuel reservoir 26 through the solenoid valve 60 which is normally open.
From the pump chamber 24. The fuel sucked into the pump chamber 24 tends to be pressurized with the rise of the plunger 23, but when 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. Overflow and no substantial pressurization of the fuel in the pump chamber 24 occurs.

On the other hand, when the solenoid valve 60 is energized while the plunger 23 is being raised, the valve body 62 is connected to the low-pressure passage 61.
, The fuel in the pump chamber 24 cannot overflow and starts to be pressurized. And pump room 2
When the fuel pressure in the valve 4 rises and overcomes the urging force of the return spring 44 of the check valve 42 and the pressure of the common rail 4 applied to the valve element 43, the check valve 42 is pushed open to discharge high-pressure fuel. The pressure is fed to the common rail 4 through the hole 41, the discharge port 45 and the supply pipe 12.

As shown in FIG. 3, the camshaft 31 has one timing gear 36 and two variable discharge high pressure pumps 5.
(A first high-pressure pump 5a and a second high-pressure pump 5b). Also, the same configuration as that shown in FIG.
Since the subscripts a and b are respectively added,
See FIG. 2 for the detailed structure and the like of the configuration marked with b.

The timing gear 36 has seven protrusions 37.
a to 37 g are provided. Further, a cam angle sensor 38 composed of an electromagnetic pickup is provided in close proximity to the timing gear 36. The timing gear and the cam angle sensor 38 constitute the G sensor 16 described above.

The projections 37a to 37f are provided at regular intervals corresponding to the top dead center position of each cylinder of the engine. More specifically, the projection 37a corresponds to 45 degrees CA before the top dead center position of the first cylinder of the engine, and hereinafter, the projection 37b is the fifth cylinder, the projection 37c is the third cylinder, and the projection 37d is the third cylinder. 6
The projection 37e of the cylinder is provided at a timing 45 ° CA before each top dead center of the second cylinder, and the projection 37f is provided at a projection 37f of the fourth cylinder. On the other hand, the projection 37g is provided close to the projection 37a so as to be clearly different from other projection intervals. Therefore, if the timing at which the interval between the pulse signals detected by the cam angle sensor 38 becomes extremely short can be detected, then the top dead center of the first cylinder comes at 45 ° CA.

On the other hand, the bottom dead center of the plunger 23a in the variable discharge high pressure pump 5a is 30 degrees CA from the top dead center of the first, third, and second cylinders in engine crank angle.
The timing is late, the top dead center is the fifth cylinder,
The timing is delayed by 30 degrees CA from the top dead center of the sixth and fourth cylinders at the engine crank angle. The plunger 23b of the other variable discharge high pressure pump 5b is
The top dead center and bottom dead center are reached at exactly the opposite timing.

Therefore, the output of each of the high-pressure pumps 5a and 5b is determined based on the output of the G sensor 16 (hereinafter referred to as G pulse) and the output of the Ne sensor 7 (output at every 15 ° CA, hereinafter referred to as Ne pulse). The top dead center timing and the bottom dead center timing of the plungers 23a and 23b can be known.

In the feedback control of the common rail pressure performed during the normal running, the closing timing of the solenoid valve 60 is given based on the bottom dead center timing of the plunger 23 detected from the G pulse and the Ne pulse. That is, as shown in FIG.
3 and a period TF (hereinafter, referred to as an output waiting period TF) using a Ne pulse corresponding to the bottom dead center timing as a reference pulse
The solenoid valve drive pulse is output with a delay. The energization of the solenoid valve 60 is started by this drive pulse, and a period TC (hereinafter, referred to as a valve closing delay TC) is related to the rise of the current.
The valve closing of the valve body 62 is executed with a delay. After that, the valve closing state of the valve body 62 is maintained by the increase in the pressure of the pump chamber 24 due to the rise of the plunger 23, so that the drive pulse is turned off after a short period TON elapses, thereby saving power consumption. . This is an advantage of opening the valve.

After the valve element 62 is closed, the period until the plunger 23 reaches the top dead center is the fuel pressurization period in the pump chamber 24, and the amount of fuel proportional to the discharge area of the hatching shown in FIG. To be pumped. Therefore, in this figure, if the output timing of the drive pulse is advanced so that the discharge area becomes large, more fuel is pumped to the common rail 4, and if the output timing is delayed, the amount of fuel pumped to the common rail 4 is reduced. Decrease. That is, 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 described. E
The CU 6, as shown in FIG. 5, calculates the engine speed Ne based on the Ne pulse (S1), and A / D converts the detected value of the accelerator sensor 8 to obtain the accelerator opening Accp (S2).

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

When the target fuel injection amount QFIN and the target common rail pressure are calculated in this way, drive control of the injector 14 and the solenoid valve 60 is executed based on these (S5, S6). Of these, in the common rail pressure control routine, as shown in FIG. 8, the first start-up control (S11, S12, S13) depends on what is set in the mode flag MF indicating the common rail pressure control condition. S1
5), second startup control (S16), normal control (S16)
17), the control of the common rail pressure is executed.

The mode flag MF = 1 indicates a state in which a first start-up control described later is to be performed.
2 indicates a state in which the second start-time control is to be performed, and mode flag MF = 3 indicates a state in which the normal control is to be performed. In addition to these 1, 2, and 3, the mode flag MF includes:
“0” is also set. MF = 0 is set immediately after the ignition key is turned on from the engine stopped state,
Immediately before that means that the engine was not driven. Hereinafter, MF = 0 is referred to as a stop mode.

Here, how the mode flag MF is set will be described first. The mode flag setting process is executed according to the flow shown in FIGS. This control process is started at the same time as the ignition is turned on. When the ignition is turned on, various flags, timers, and the like are reset.

In the mode flag setting process, first, it is determined whether or not the mode flag MF is "0", that is, whether the stop mode is set (S21). Since the vehicle is in the stop mode immediately after the engine is started, the process proceeds to S23 in the first determination to determine whether or not there is a Ne pulse input. Ne
If there is no pulse input (S23: NO), it is determined whether there is a G pulse input (S25). And S2
If both of S3 and S25 are determined to be NO, it is determined that the engine has not started cranking yet, and the process once exits. On the other hand, if it is determined that a Ne pulse or a G pulse has been input (S23: YES or S25: YES), the mode flag MF is set to "1" and the process exits (S27).

In this manner, when the engine starts cranking and enters the first start-time control mode, the determination in S21 becomes NO this time, so the routine proceeds to S31, in which the mode flag M
It is determined whether or not F is “1”. Immediately after the start of cranking, since MF = 1, the flow shifts to S33, and it is determined whether or not the timer T reset at the time of ignition-on indicates that 5 seconds have elapsed. If 5 seconds have not elapsed, it is determined whether or not the cylinder has been identified, specifically, the pulse of the protrusion 37a corresponding to 45 ° CA before the top dead center of the first cylinder is determined by the G pulse input of the G sensor 16. It is determined whether or not the operation has been completed (S35). If the cylinder has been identified (S35: YES), the mode flag MF is set to "2" and the process exits (S37). On the other hand, if it is determined in S33 that 5 seconds have elapsed, the mode flag M
F, timer T, etc. are initialized and the process exits (S3
9). Also, even before the lapse of 5 seconds, if the cylinder discrimination has not been performed (S35: NO), the mode flag MF =
The process exits with the value of 1.

Here, the reason why the elapse of 5 seconds is determined by the timer T is that the control at the time of the first startup is continued for too long because there is some abnormality in the detection state by the sensor. This is to restart the processing of this routine from the beginning. In this way, it is set that the first start-time control should be performed immediately after cranking (MF = 1), and that the control should be shifted to the second start-up control when the cylinder discrimination is possible (MF = 1). = 2) is set. Therefore, in this routine, S31 will be NO at some point, and the processing after S41 will be executed.

In S41, it is determined whether or not "2" is set in the mode flag MF. Then, if determined to be YES, it is checked whether engine stall has occurred (S43). In this confirmation, it is determined as YES when the Ne pulse is not input for a predetermined time or more. If engine stall has not occurred (S4
3: NO), it is determined whether or not the engine speed Ne is equal to or higher than 200 rpm (S45). If Ne <200 rpm, it is further determined whether or not the actual common rail pressure PC is 25 MPa or more (S47). If either of S45 and S47 is YES, it is determined whether or not cylinder discrimination is possible (S49). If the cylinder can be determined (S49: YES), the mode flag MF is finally set to "3" (S51). Thereafter, feedback control as normal control is started for the first time.

It is to be noted that the determination regarding the engine speed Ne and the actual common rail pressure PC is based on whether cranking and the subsequent transient state have been completed or not, even if the transient state has not been completed. This is because the control is shifted to the normal control after confirming whether or not has increased. In S49, it is determined whether or not cylinder discrimination is possible because normal control cannot be performed normally in a state where cylinder discrimination has not been performed, so that transition to normal control in such a state is not performed. This is for precaution.

Thus, immediately after the start of engine cranking, the first control at the time of starting, the second control at the time of starting, and finally the normal control are selected. next,
The contents of the first startup control (S15 in FIG. 8) will be described. This control is executed according to a subroutine shown in FIG.

First, it is determined whether or not the timer T1 has reached 32.8 msec (S61). This timer T1
Are initialized to "0" when this subroutine is executed for the first time. Then, during T1 <32.8 msec, the solenoid valve 60a on the first high-pressure pump 5a side is closed,
The state where the solenoid valve 60b on the second high-pressure pump 5b side is opened (PCV # 1: ON, PCV # 2: OFF) is maintained (S63). On the other hand, when T1 ≧ 32.8 msec (S61: NO), it is determined whether or not the timer T1 has reached 65.6 msec (S65). And 32.8
While msec <T1 <65.6 msec (S6
5: YES), contrary to S63, the state where the solenoid valve 60a on the first high-pressure pump 5a side is opened and the solenoid valve 60b on the second high-pressure pump 5b side is closed (PCV # 1: OFF, PCV # 1)
# 2: ON) is maintained (S67). And T1 ≧ 6
When 5.6 msec is reached (N for both S61 and S65)
O), the timer T1 is reset (S69).

Thus, the solenoid valves 60a and 60b are in a state of repeating valve closing and valve opening every 32.8 msec. Therefore, during the period when the rise of the plunger 23 and the closing of the solenoid valve 60 overlap, the fuel oil is pumped, and during the period when the lowering of the plunger 23 and the opening of the solenoid valve 60 overlap, the fuel oil is supplied to the plunger chamber. Of fuel oil is made.
Since the valve opening period and the valve closing period are evenly halved, during this control, the pumping of the fuel oil is performed in half of the ascent stroke of the plunger 23 without any synchronization. Thus, fuel oil can be sucked into the plunger chamber in half of the downward stroke of the plunger 23.

Next, the contents of the second start control (S16 in FIG. 8) will be described. This control is executed according to a subroutine shown in FIG. Then, control is performed as shown in the timing chart of FIG. First,
In the first step, Ne pulse No. It is determined whether or not 4 has been input (S71). The Ne pulse is shown in FIG.
As shown in FIG. 7, the pulse signal is a pulse signal generated at every 15 ° CA of the crank angle. 0 and each position No. 1, No. 2, ... can be distinguished. The reference position No. 0 is configured to appear with a delay of 15 degrees CA relative to the projections 37a to 37f of the G sensor 16 corresponding to each cylinder. Therefore,
Ne pulse No. The fact that 4 has been input means that it has rotated by 75 degrees CA after the G sensor input. This means the timing corresponding to the top dead center or the bottom dead center of the plungers 23a and 23b in each high-pressure pump.

Ne pulse No. If 4 is input (S71: YES), it is determined whether the cylinder determined from the current G sensor input is any of the first, second, or third cylinder (S73). . And these first,
When it is determined that the second or third cylinder has been determined (S73: YES), the first high-pressure pump 5
a side solenoid valve 60a is closed, and the second high pressure pump 5b side solenoid valve 60b is opened (PCV # 1: ON, PC
V # 2: OFF) is maintained (S75). On the other hand, if any other cylinder is determined (S73: N
O) Contrary to S75, the solenoid valve 60a on the first high-pressure pump 5a side is opened, and the solenoid valve 60b on the second high-pressure pump 5b side is opened.
Is closed (PCV # 1: OFF, PCV # 2: O
N) is maintained (S77).

On the other hand, in the normal control (S17 in FIG. 8), the processing is executed according to the procedure shown in FIG. This process is executed as an interrupt process synchronized with the compression stroke of each cylinder of the diesel engine 2. First, the intake of the target common rail pressure PFIN and the target fuel injection amount QF
IN is taken in (S81, S83).

The target common rail pressure PFI
Based on N and the target fuel injection amount QFIN, a drive pulse output waiting period calculation map as shown in FIG.
Reference value of drive pulse output waiting period (reference output waiting period)
TFBASE is calculated (S85).

Subsequently, the detection value of the common rail pressure sensor 9 is A / D converted to calculate the actual common rail pressure PC (S
87). Then, the actual common rail pressure PC is compared with the target common rail pressure PFIN, and a pressure difference ΔP = PC−PF
The correction amount TFFB for the reference output waiting period TFBASE is calculated according to IN (S89). In calculating the correction amount TFFB, a generally well-known PID control method is used.

Subsequently, the control output waiting period TF is calculated by subtracting the delay time TC when the solenoid valve is driven from the sum of the reference output waiting period TFBASE and the correction amount TFFB (S9).
1). The reason for subtracting the delay time TC is to match the solenoid valve drive timing with the target timing.

The solenoid valves 60a, 60b,... Are controlled in accordance with the output waiting period TF calculated in this manner, and the pressure in the common rail 4 is adjusted so that the fuel injection according to the operating conditions such as the engine speed Ne and the accelerator opening Accp is performed. The target common rail pressure PFIN suitable for performing is maintained.

As described above, according to the present embodiment, the common rail pressure is reduced immediately after the start of the engine, and the normal feedback control cannot be performed in order to reach the target common rail pressure. , First and second
Since the control at the time of starting is performed, the common rail pressure can be quickly increased.

In particular, when the cylinder discrimination can be performed, the control is immediately shifted to the second control at the time of starting, so that the capacity of the variable discharge amount high pressure pump 5 is maximized and the fuel oil is sucked and pumped. As a result, the common rail pressure can be increased more quickly than in the case where only the first start-up control is performed as in Japanese Patent Application Laid-Open No. 2-146256.

In addition to the second start-up control, the first
Since the control at the time of starting is also used, the control at the time of starting can be performed from a state where the cylinder cannot be determined as immediately after the start of cranking, and the common rail pressure can be more quickly increased. Although the embodiment of the present invention has been described above, the present invention is not limited to this, and it is needless to say that various embodiments can be adopted without departing from the gist thereof.

For example, a configuration may be adopted in which only the second startup control is performed without performing the first startup control. In the first start-up control, the valve opening period and the valve closing period were both set to 32.8 msec in the embodiment. However, as in Japanese Patent Application Laid-Open No. 2-146256, the crankshaft rotation speed in the initial stage of cranking was set. The valve closing period is set in accordance with the period until the externally opened solenoid valve can self-close, and the valve opening period is set in accordance with the period in which fuel oil can be sufficiently sucked into the plunger chamber at the crankshaft speed. You can keep it.

[0059]

As described above, according to the fuel injection device for an internal combustion engine of the present invention, at the time of starting the internal combustion engine, the performance of the high-pressure pump itself is maximized, and the internal combustion engine is more efficiently and efficiently. The common rail pressure can be increased quickly. Therefore, the startability of the accumulator-type internal combustion engine can be greatly improved.

[Brief description of the drawings]

FIG. 1 is a configuration diagram illustrating a system according to an embodiment.

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

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

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

FIG. 5 is a flowchart of a main routine for calculating a target fuel injection amount and a target common rail pressure performed by an ECU.

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

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

FIG. 8 is a flowchart of a common rail pressure control routine.

FIG. 9 is a flowchart of a mode flag setting routine for common rail pressure control.

FIG. 10 is a flowchart of a mode flag setting routine for common rail pressure control.

FIG. 11 is a flowchart of a first startup control routine for common rail pressure control.

FIG. 12 is a flowchart of a second startup control routine for common rail pressure control.

FIG. 13 is a timing chart showing a relationship between a Ne pulse or the like and a solenoid valve opening / closing control state of the high-pressure pump in the second startup control.

FIG. 14 is a flowchart of a normal control routine for common rail pressure control.

FIG. 15 is a map for calculating a reference output waiting period.

FIG. 16 is a timing chart showing a conventional startup control state.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Common rail type fuel injection control apparatus, 2 ... Diesel engine, 3 ... Injector, 4 ... Common rail, 5 ... Variable discharge amount high pressure pump, 6 ...
Electronic control unit (ECU), 7 ··· rotational speed sensor, 8 ·
..Accelerator sensors, 9 ... common rail pressure sensors
10: fuel tank, 11: low pressure supply pump, 1
2 ... supply pipe, 13 ... pipe, 14 ... control valve, 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 element.

──────────────────────────────────────────────────の Continuation of front page (51) Int.Cl. ⁷ identification code FI F02M 47/00 F02M 47/00 E 59/42 59/42 (58) Field surveyed (Int.Cl. ⁷ , DB name) F02D 41/00-41/40 F02M 39/00-71/04

Claims (1)

(57) [Claims] 1. A fuel pumping means for pumping fuel in a plunger chamber to a pressure accumulating chamber by opening and closing a control valve in accordance with movement of a plunger fitted in the plunger chamber, and setting operation timing of the control valve. The plastic
The reference signal corresponding to the bottom dead center of the
The cylinder discriminating sensor for discriminating
Based on the value of at least one of the
A reference signal output means for outputting; a pressure detection means for detecting a fuel pressure in the pressure accumulating chamber; a value detected by the pressure detecting means being compared with a target pressure for fuel injection; Like pressure
Feedback control means for setting the operation timing of the control valve based on the reference signal and for driving and controlling the fuel pumping means, wherein the fuel injection of the internal combustion engine injecting fuel with the fuel stored in the pressure accumulation chamber In the apparatus, at the time of starting the internal combustion engine, a first start-up control is performed in which the opening / closing operation of the control valve is repeated every predetermined time to feed the fuel sucked into the plunger chamber to the pressure accumulating chamber.
Subsequently , the reference signal output means outputs the reference signal.
After the output of the control signal is detected , the control valve is closed during the ascent of the plunger, which is determined from the reference signal by the reference signal output means, and the control valve is opened during the decrease, which is also determined. the second start-up time control the real
By row, a fuel injection system for an internal combustion engine, characterized in that it comprises a start control means for rapidly increasing the fuel pressure in the accumulator chamber.