JP3052593B2 - Fuel injection amount control 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 an internal combustion engine having a fuel injection pump and a fuel injection nozzle, and more particularly, to a fuel injection for controlling a fuel injection amount in response to a change in valve opening pressure at the fuel injection nozzle. The present invention relates to a quantity control device.

[0002]

2. Description of the Related Art Conventionally, in an internal combustion engine provided with a fuel injection pump and a fuel injection nozzle, fuel injection amount control is performed so that the fuel injection amount from the fuel injection nozzle coincides with a target value.

For example, in an electronically controlled diesel engine, the fuel in a high-pressure chamber is pumped to a fuel injection nozzle and injected into each cylinder of the engine by a lift of a plunger in a fuel injection pump. Then, the spill ring, the spill valve, and the like provided in the fuel injection pump are driven and controlled by the actuator such that the fuel injection amount at that time becomes the target injection amount determined according to the engine operating state. Further, by this control, the plunger high pressure chamber is opened to the fuel chamber, and a part of the fuel in the plunger high pressure chamber overflows (spills) to the fuel chamber. Thus, the end of the fuel pumping from the fuel injection pump to the fuel injection nozzle, that is, the end timing of the fuel injection from the fuel injection nozzle to each cylinder is controlled.

[0004] However, even in an electronically controlled diesel engine in which the fuel injection amount is controlled as described above, the fuel injection nozzle is generally a mere mechanical automatic valve. Further, since the fuel injection nozzle is a mechanical automatic valve, there is a possibility that the actual fuel injection amount from the nozzle may change due to the temporal decrease of the valve opening pressure. That is, this type of fuel injection nozzle includes a needle valve and a spring for adjusting the valve opening pressure of the needle valve, and is opened by obtaining a fuel pressure equal to or higher than a predetermined level. The valve opening pressure of the needle valve is adjusted in advance to a constant value by a spring. Then, when the force of the spring is weakened due to the temporal change of the fuel injection nozzle, the valve opening pressure of the needle valve has become smaller than the set pressure initially set. Therefore, in that case,
The amount of fuel injected from the fuel injection nozzle deviates from the desired target injection amount, and there is a possibility that smoke and nitrogen oxides (NOx) from the engine may increase.

Here, as a technology capable of coping with the above-mentioned inconvenience, at present, Japanese Patent Application Laid-Open No.
No. 526 discloses a “fuel injection nozzle device” as an example. In this prior art, the fuel injection nozzle is provided with a valve opening pressure adjusting means driven by hydraulic pressure for adjusting the valve opening pressure of the needle valve. Further, the fuel injection nozzle is provided with a lift sensor for detecting a valve opening timing when the needle valve is lifted, and a pressure sensor for detecting a fuel pressure applied to the nozzle. Then, the optimal valve opening pressure according to the engine operating state at that time is determined as the target valve opening pressure, and based on the detection results of the lift sensor and the pressure sensor, the actual valve opening pressure of the needle valve (actual valve opening pressure). Is detected. Then, the valve-opening pressure adjusting means is driven and controlled so that the actual valve-opening pressure matches the target valve-opening pressure, whereby the valve-opening pressure at the fuel injection nozzle is increased to a required valve-opening pressure according to the engine operating state. It was to be adjusted to precision.

[0006]

Therefore, in the above-mentioned prior art, in order to control the injection amount from the fuel injection nozzle to the target injection amount, it is essential to provide a valve opening pressure adjusting means in the nozzle. Had a configuration. For this reason, the fuel injection nozzle to be used is different from the usual one and must be a new fuel injection nozzle specially provided with a valve opening pressure adjusting means, resulting in a complicated structure. Further, in the prior art, in addition to the usual fuel injection amount control, special control for driving the valve opening pressure adjusting means has been required.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and has as its object to provide a method for adjusting the valve opening pressure at a fuel injection nozzle without providing any special means, such as a change with time or a manufacturing error. It is an object of the present invention to provide a fuel injection amount control device for an internal combustion engine that can stably perform high-precision fuel injection amount control over a long period of time in response to a change in valve opening pressure caused by the above.

[0008]

In order to achieve the above-mentioned object, the present invention provides a fuel injection pump for fuel injection.
Used for internal combustion engines that pump fuel to the injection nozzle
Be one which, detecting means for detecting a fuel pressure at the time of valve opening of the fuel injection nozzle as opening pressure, caused by changes in the valve opening pressure based on the detection result of the detecting means
From the fuel injection pump to the fuel injection nozzle
A control means for calculating a target injection amount for fuel injection in consideration of a change in the residual fuel amount in the fuel system, and controlling the driving of the fuel injection pump based on the calculation result. Here, FIG. 1 shows a conceptual configuration of one embodiment for suitably implementing the present invention. That is, in the apparatus shown in the figure, a fuel injection nozzle M2 that opens when a fuel pressure equal to or higher than a predetermined level is obtained and injects fuel into the internal combustion engine M1, and a drive that feeds fuel to the fuel injection nozzle M2 by pressure. A controlled fuel injection pump M3, valve opening pressure detecting means M4 for detecting a fuel pressure when the fuel injection nozzle M2 is opened as a valve opening pressure, a detection result of the valve opening pressure detecting means M4, and a predetermined reference pressure. And a valve opening pressure deviation calculating means M5 for calculating a difference between the valve opening pressure deviation and the valve opening pressure deviation calculating means M5. Residual fuel amount change amount calculating means M7 for calculating the change amount of the residual fuel amount
And a corrected target injection amount calculating means M8 for calculating the corrected target injection amount by reflecting the calculation result of the residual fuel amount change amount calculating means M7 to a target injection amount for the next fuel injection;
Pump control means M9 for controlling the driving of the fuel injection pump M3 based on the result of calculation by the corrected target injection amount calculating means M8.

[0009]

According to the conceptual configuration shown in FIG. 1, when the fuel is pumped from the fuel injection pump M3 to the fuel injection nozzle M2, the valve opening pressure detecting means M4 opens the fuel injection nozzle M2. The fuel pressure at that time is detected as the valve opening pressure. The valve opening pressure deviation calculating means M5 calculates a difference between the detected valve opening pressure and a predetermined reference pressure as a valve opening pressure deviation. That is, when the valve opening pressure changes, the change is calculated as the valve opening pressure deviation.

Further, the residual fuel amount change amount calculating means M7 calculates a change amount of the residual fuel amount in the fuel system M6 based on the calculated valve opening pressure deviation. Here, due to the difference in the valve opening pressure at the fuel injection nozzle M2, the fuel system M
It is known that the amount of change in the amount of residual fuel within 6 changes. Also, due to the difference in the amount of change in the residual fuel amount,
It is known that the fuel injection amount from the fuel injection nozzle M2 changes. Then, the corrected target injection amount calculating means M8
Then, the corrected target injection amount is calculated by reflecting the calculated change amount of the residual fuel amount on the target injection amount for the next fuel injection. That is, the target injection amount is corrected based on the change amount of the residual fuel amount affected by the change in the valve opening pressure. Then, the pump control means M9 drives and controls the fuel injection pump M3 based on the calculated corrected target injection amount,
Fuel is pressure-fed to the fuel injection nozzle M2 through the fuel system M6.

Therefore, in each fuel injection, the amount of fuel pumped from the fuel injection pump M3 to the fuel injection nozzle M2 takes into account the change in the residual fuel amount due to the change in the valve opening pressure of the fuel injection nozzle M2. The effect of the change in the amount of residual fuel is eliminated. Therefore, even if the valve opening pressure in the fuel injection nozzle M2 changes with time, the desired amount of fuel is injected into the internal combustion engine M1 without being affected by the change.

[0012]

【Example】

(First Embodiment) Hereinafter, a first embodiment in which a fuel injection amount control device for an internal combustion engine according to the present invention is embodied in an electronically controlled diesel engine of an automobile will be described in detail with reference to FIGS.

FIG. 2 shows a schematic configuration of a diesel engine system with a supercharger in this embodiment, and FIG. 3 shows the distribution type fuel injection pump 1 in an enlarged manner. The fuel injection pump 1 includes a drive pulley 2 which is drivingly connected to a crankshaft 40 of a diesel engine 3 as an internal combustion engine via a belt or the like. When the drive pulley 2 is driven to rotate by the crankshaft 40 and the fuel injection pump 1 is driven, fuel injection provided for each cylinder (here, four cylinders are provided) of the diesel engine 3 is provided. Fuel is pumped to the nozzle 4 through the fuel pipe 4a.

In this embodiment, the fuel injection nozzle 4 is an automatic valve including a needle valve and a spring for adjusting the valve opening pressure of the needle valve. The valve is opened. Therefore, the fuel injected from the fuel injection pump 1 applies a fuel pressure P equal to or higher than a predetermined level to the fuel injection nozzle 4, whereby fuel is injected from the nozzle 4 to the diesel engine 3.

The fuel injection pump 1 has a drive shaft 5
The drive pulley 2 is attached to the tip of the drive shaft 5. In the middle of the drive shaft 5 is provided a fuel feed pump 6 (developed by 90 degrees in this figure) composed of a vane type pump. A disk-shaped pulsar 7 is attached to the base end side of the drive shaft 5. On the outer peripheral surface of the pulsar 7, missing teeth of the same number as the number of cylinders of the diesel engine 3, that is, four (in total, “eight”) missing teeth are formed at equal angular intervals in this embodiment. Also, between each missing tooth,
Fourteen projections (a total of "56") are formed at equal angular intervals. The base end of the drive shaft 5 is connected to the cam plate 8 via a coupling (not shown).

A roller ring 9 is provided between the pulsar 7 and the cam plate 8. A plurality of cam rollers 10 facing the cam face 8a of the cam plate 8 are mounted in the circumferential direction of the roller ring 9. The cam faces 8 a are provided in the same number as the number of cylinders of the diesel engine 3. The cam plate 8 is urged by a spring 11 so as to engage with the cam roller 10.

A base end of a plunger 12 for fuel pressurization is attached to the cam plate 8 so as to be integrally rotatable. Then, the cam plate 8 and the plunger 12 are integrally driven to rotate as the drive shaft 5 rotates.
That is, the rotational force of the drive shaft 5 is transmitted to the cam plate 8 via the coupling, so that the cam plate 8 rotates while engaging with the cam roller 10. As a result, the cam plate 8 is reciprocated in the horizontal direction in the figure by the same number as the number of cylinders while being rotated, and the plunger 12 is reciprocated in the same direction while being rotated. That is, the cam face 8a is the cam roller 1 of the roller ring 9.
Plunger 12 moves forward (lift) in the process of climbing to zero
Is done. On the contrary, the cam face 8a is
Plunger 12 moves back in the process of getting over 0 (down)
Is done.

A cylinder 14 is formed in the pump housing 13, and the plunger 12 is fitted into the cylinder 14. A high-pressure chamber 15 is provided between the tip surface of the plunger 12 and the bottom surface of the cylinder 14. In addition, suction grooves 16 and distribution ports 17 are formed on the outer periphery of the distal end side of the plunger 12 by the same number as the number of cylinders. Further, corresponding to the suction groove 16 and the distribution port 17,
A distribution passage 18 and a suction port 19 are formed in the pump housing 13.

In the pump housing 13 of this embodiment, a delivery valve 3 composed of a constant pressure valve (CPV) is provided at the outlet side of each distribution passage 18.
6 are provided. The delivery valve 36 is for preventing the backflow of the fuel pressure-fed from the distribution passage 18 to the fuel pipe 4a, and is opened by obtaining a fuel pressure P of a certain level or more. .

When the drive shaft 5 is rotated and the fuel feed pump 6 is driven, fuel is introduced from a fuel tank (not shown) into the fuel chamber 21 through the fuel supply port 20. In the suction stroke in which the plunger 12 is moved back and the high-pressure chamber 15 is depressurized, fuel is introduced from the fuel chamber 21 into the high-pressure chamber 15 by one of the suction grooves 16 communicating with the suction port 19. on the other hand,
In the compression stroke in which the plunger 12 moves forward and the high-pressure chamber 15 is pressurized, the fuel is pressure-fed from the distribution passage 18 to the fuel injection nozzle 4 of each cylinder through the fuel pipe 4a and injected.

In the pump housing 13, the high pressure chamber 1
A spill passage 22 for causing fuel to overflow (spill) is formed between the fuel chamber 5 and the fuel chamber 21. An electromagnetic spill valve 23 is provided in the middle of the spill passage 22. Then, the electromagnetic spill valve 23 is opened and closed to adjust the spill of the fuel from the high-pressure chamber 15. The electromagnetic spill valve 23 is a normally open type valve. When the coil 24 is not energized (off), the spill passage 22 is opened by the valve body 25, that is, the valve is opened, and the fuel in the high-pressure chamber 15 is released from the fuel chamber 21. Spilled into On the other hand, when the coil 24 is energized (turned on), the spill passage 22 is closed by the valve body 25, that is, the valve is closed, and the spill of fuel from the high-pressure chamber 15 to the fuel chamber 21 is shut off.

Therefore, the electromagnetic spill valve 23 is controlled to be turned on and off by energization, whereby the valve 23 is controlled to close and open, and the spill of fuel from the high-pressure chamber 15 to the fuel chamber 21 is adjusted. When the electromagnetic spill valve 23 is opened during the compression stroke of the plunger 12, the high-pressure chamber 1 is opened.
The fuel in the fuel injection nozzle 4 is depressurized and the fuel injection from the fuel injection nozzle 4 is stopped. That is, even when the plunger 12 moves forward, while the electromagnetic spill valve 23 is opened,
The fuel pressure in the high-pressure chamber 15 does not increase and the fuel injection nozzle 4
Is not injected. Also, during the forward movement of the plunger 12, by controlling the valve opening timing of the electromagnetic spill valve 23, the end timing of the fuel injection from the fuel injection nozzle 4 is adjusted, and the fuel injection amount to the cylinder is controlled. .

Below the pump housing 13, there is provided a timer device (expanded by "90 degrees" in this figure) 26 for controlling the fuel injection timing to the advance side or the retard side. . This timer device 26 changes the rotation position of the roller ring 9 with respect to the rotation direction of the drive shaft 5 to change the timing at which the cam face 8a engages with the cam roller 10, that is, the timing at which the plunger 12 reciprocates. belongs to.

The timer device 26 is driven by control hydraulic pressure, and includes a timer housing 27 and a timer piston 28 fitted in the housing 27. Further, both sides of the timer piston 28 in the timer housing 27 are a low-pressure chamber 29 and a pressurizing chamber 30, respectively. The low-pressure chamber 29 has a timer piston 28
A timer spring 31 is provided to urge the pressure chamber 30 into the pressure chamber 30. Further, the timer piston 28 is connected to the roller ring 9 via a slide pin 32.

The fuel pressurized by the fuel feed pump 6 is introduced into the pressurizing chamber 30. The position of the timer piston 28 is determined by the balance between the fuel pressure and the urging force of the timer spring 31. Further, by determining the position of the timer piston 28, the position of the roller ring 9 is determined, and the reciprocating timing of the plunger 12 via the cam plate 8 is determined.

As the control oil pressure of the timer device 26, the fuel pressure inside the fuel injection pump 1 is used. To adjust the fuel pressure, the timer device 26 is provided with a timer control valve (TCV) 33. That is, a communication path 34 is provided between the pressurizing chamber 30 and the low-pressure chamber 29 of the timer housing 27, and the communication path 34
The TCV 33 is provided in the middle of. The TCV 33 is an electromagnetic valve whose opening and closing are controlled by a duty-controlled energization signal. The TCV 33 is controlled to open and close to adjust the fuel pressure in the pressurizing chamber 30. Then, by adjusting the fuel pressure, the reciprocating timing of the plunger 12 is controlled, whereby the fuel injection timing from the fuel injection nozzle 4 is controlled to be advanced or retarded.

On the upper part of the roller ring 9, a rotation speed sensor 35 composed of an electromagnetic pickup coil is mounted so as to face the outer peripheral surface of the pulser 7. This rotation speed sensor 35
Detects the passage of the pulsar when it is crossed by a projection or the like of the pulsar 7 and outputs the signal as a pulse signal. That is, the rotation speed sensor 35 outputs an engine rotation pulse signal for each constant crank angle. At the same time, the rotation speed sensor 35 outputs an engine rotation pulse signal corresponding to a fixed crank angle due to a missing tooth of the pulser 7 as a reference position signal. The rotation speed sensor 35 outputs a series of engine rotation pulse signals as signals for obtaining the engine rotation speed NE.
Since the rotation speed sensor 35 is integrated with the roller ring 9, it can output a reference engine rotation pulse signal at a fixed timing with respect to the reciprocation of the plunger 12 regardless of the control operation of the timer device 26. .

Next, the diesel engine 3 will be described. 2, in the diesel engine 3, a main combustion chamber 44 corresponding to each cylinder is formed by a cylinder bore 41, a piston 42, and a cylinder head 43. In the cylinder head 43, sub combustion chambers 45 communicating with the main combustion chambers 44 are formed. Then, fuel is injected into each sub-combustion chamber 45 from each fuel injection nozzle 4. Further, each sub-combustion chamber 45 is provided with a well-known glow plug 46 as a start-up assist device.

As shown in FIGS. 2 and 4, each fuel injection nozzle 4 of this embodiment is provided with a pressure sensor 47 as valve opening pressure detecting means. The pressure sensor 47 detects the pressure of the fuel fed from the fuel injection pump 1 to each of the fuel injection nozzles 4, that is, the fuel pressure P, and also detects the fuel pressure P when the nozzles 4 are opened. A signal corresponding to the magnitude is output.

On the other hand, the diesel engine 3 is provided with an intake passage 49 and an exhaust passage 50 communicating with each cylinder. Further, a compressor 52 of a turbocharger 51 constituting a supercharger is provided in the intake passage 49,
A turbine 53 of a turbocharger 51 is provided in the exhaust passage 50.
Is provided. Further, a waste gate valve 54 is provided in the exhaust passage 50. As is well known, the turbocharger 51 uses the energy of the exhaust gas to rotate the turbine 53, and rotates the compressor 52 coaxially therewith to increase the pressure of the intake air. And
By increasing the pressure of the intake air, high-density air is sent into the main combustion chamber 44 and a large amount of fuel injected through the sub-combustion chamber 45 is burned, so that the output of the diesel engine 3 is increased. Further, by opening and closing the waste gate valve 54, the pressure increase level of the intake air by the turbocharger 51 is adjusted.

Between the intake passage 49 and the exhaust passage 50,
Exhaust gas recirculation valve passage (EG
An R path 56 is provided. Then, a part of the exhaust gas in the exhaust passage 50 is recirculated by the EGR passage 56 near the intake port 55 in the intake passage 49.
An EGR valve 57 is provided in the middle of the EGR passage 56, and the EGR valve 57 controls the exhaust gas recirculation amount (E
GR amount) is adjusted. Further, in order to open and close the EGR valve 57, an electric vacuum regulating valve (EVRV) 58 whose opening is adjusted is controlled.
Is provided. Then, EGRV58 is used for EGR
When the valve 57 is driven to open and close, the EGR passage 5
E guided from the exhaust passage 50 to the intake passage 49 through
The GR amount is adjusted.

A throttle valve 59 is provided in the middle of the intake passage 49. The throttle valve 59 is opened and closed in conjunction with the depression of an accelerator pedal 60. In the intake passage 49,
A bypass passage 61 is provided alongside the throttle valve 59, and a bypass throttle valve 62 is provided in the passage 61. In order to open and close the bypass throttle valve 62, a two-stage diaphragm chamber type actuator 63 is provided. Also, two vacuum switching valves (VS) for driving the actuator 63 are provided.
V) 64, 65 are provided. And each VSV6
The bypass throttle valve 62 is controlled to open and close by driving the actuator 63 with the on / off control of the valves 4 and 65. For example, the bypass throttle valve 62 is controlled to be in a half-open state in order to reduce noise and vibration during idling operation, is controlled to be in a fully open state in normal operation, and is controlled to be in a fully closed state in order to smoothly stop the operation. Is done.

The above-described electromagnetic spill valve 23, TCV3
3, glow plug 46, EVRV58 and each VSV6
4 and 65 are electronic control units (hereinafter simply referred to as “ECU”).
71 are electrically connected to each other. The drive timing of each of the members 23, 33, 46, 58, 64, 65 is controlled by the ECU 71.

As sensors for detecting the operating state of the diesel engine 3, in addition to the rotation speed sensor 35 described above, the following various sensors are provided. That is, near the air cleaner 66 provided at the inlet of the intake passage 49, an intake air temperature sensor 72 that detects the intake air temperature THA and outputs a signal corresponding to the magnitude of the detected value is provided. In the vicinity of the throttle valve 59, the valve 5
An accelerator sensor 73 that detects an accelerator opening ACCP corresponding to the engine load from the open / close position 9 and outputs a signal corresponding to the magnitude of the detected value. In the vicinity of the intake port 55, an intake pressure sensor 74 that detects the pressure of the intake air after being supercharged by the turbocharger 51, that is, the supercharging pressure PiM, and outputs a signal corresponding to the magnitude of the detected value. Is provided. Further, a water temperature sensor 7 for detecting the temperature of the cooling water of the diesel engine 3, that is, the cooling water temperature THW, and outputting a signal corresponding to the magnitude of the detected value.
5 are provided. Further, a crank angle sensor 76 for detecting a rotation reference position of the crankshaft 40, for example, a rotation position of the crankshaft 40 with respect to a top dead center of a specific cylinder, and outputting a signal corresponding to the rotation position is provided. Further, a transmission (not shown) is provided with a vehicle speed sensor 77 for detecting a vehicle speed (vehicle speed) SPD. The vehicle speed sensor 77 includes a magnet 77a rotated by an output shaft of the transmission. When the reed switch 77b is periodically turned on by the magnet 77a, a pulse signal corresponding to the vehicle speed SPD is output.

In this embodiment, the ECU 71 controls the valve opening pressure deviation calculating means, the residual fuel amount change amount calculating means, and the like.
The corrected target injection amount calculation means and the pump control means are configured, and the ECU 71 includes the above-described sensors 72 to 7.
7. The rotation speed sensor 35 and the pressure sensor 47 are connected respectively. In addition, the ECU 71 controls the sensors 35, 47,
Based on each signal output from 72 to 77, the electromagnetic spill valve 23, TCV 33, glow plug 46, EVRV 58
And the VSVs 64 and 65 are suitably controlled.

Next, the configuration of the ECU 71 will be described with reference to the block diagram of FIG. The ECU 71 includes a central processing unit (CPU) 81, a read-only memory (ROM) 82 in which a predetermined control program, a map, and the like are stored in advance,
A random access memory (RAM) 83 for temporarily storing the calculation results of the PU 81, a backup RAM 84 for storing the stored data, and the like are provided. And ECU
Reference numeral 71 denotes a logical operation circuit in which these units 81 to 84 are connected to an input port 85, an output port 86, and the like via a bus 87.

The input port 85 is provided with the above-mentioned intake air temperature sensor 72, accelerator sensor 73, intake air pressure sensor 74, water temperature sensor 75 and pressure sensor 47.
9, 90, 91, 92, multiplexer 94 and A / D
It is connected via a converter 95. Similarly, the input port 85 is connected to the above-described rotation speed sensor 35, crank angle sensor 76, and vehicle speed sensor 77 via a waveform shaping circuit 96. Then, the CPU 81 controls each of the sensors 35, 47, 72 to 7 input through the input port 85.
7 are read as input values. or,
The output port 86 is connected to each of the driving circuits 97, 98, 99, 10
Electromagnetic spill valve 23, TCV via 0, 101, 102
33, glow plug 46, EVRV58 and each VSV6
4, 65, etc. are connected. Then, the CPU 81 suitably controls the electromagnetic spill valve 23, the TCV 33, the glow plug 46, the EVRV 58, and the VSVs 64, 65 based on the input values read from the sensors 35, 47, 72 to 77, respectively.

In this embodiment, the CPU 81 has a timer function. Also, in this embodiment,
The glow plug 46 and the pressure sensor 47 are provided for each cylinder of the diesel engine 3.
Only one of them is shown in the block diagram of FIG.

Next, the processing operation for controlling the fuel injection amount executed by the ECU 71 will be described with reference to FIGS.
0 will be described. FIG. 6 is a flowchart showing a “subroutine” process executed at each time ti measured by the timer function of the CPU 81 among the processes executed by the ECU 71.

When the process proceeds to this routine, first, at step 110, the fuel pressure P is sampled based on the signal from the pressure sensor 47. Subsequently, in step 120, the fuel pressure Pi at the time ti at that time is calculated.

Next, in step 130, a one-time differential value (dPi / dti) is calculated as a change rate of the fuel pressure Pi at the time ti at that time. Further, in step 140, the fuel pressure P at the current time ti
The second derivative (d ² Pi / d) corresponding to the change in the rate of change of i
ti ² ) is calculated.

In step 150, the fuel pressure Pi determined this time and the one-time differential value (dPi / dt)
i) and the second derivative (d ² Pi / dti ² ) at time ti
Are stored in the RAM 83 as calculation data corresponding to the above, and the subsequent processing is temporarily terminated.

Therefore, according to the above-described "subroutine" processing, each time one fuel injection is executed, the fuel pressure Pi corresponding to each time ti and the one-time differential value (dPi / dti)
And the second derivative (d ² Pi / dti ² ) are sequentially stored in the RAM 83 as calculation data.

FIG. 7 shows “ts, ts,” for calculating the injection start time ts and the injection start pressure Ps used for controlling the fuel injection amount, among the processes executed by the ECU 71.
Is a flowchart showing processing of a "Ps calculation routine", which is periodically executed at predetermined time intervals.

When the process proceeds to this routine, first, at step 210, the fuel pressure Pi corresponding to the time ti stored in the RAM 83 and its one-time differential value (d
Pi / dti) and time t (i−
The fuel pressure P (i-1) corresponding to 1) is read.

Subsequently, at step 220, the time t
The fuel pressure Pi corresponding to i is the time t (i−
It is determined whether the fuel pressure is higher than the fuel pressure P (i-1) corresponding to 1). If the fuel pressure Pi is not higher than the previous fuel pressure P (i-1), the fuel pressure P
It is determined that the process is not an increase process, and the process jumps to step 210 and repeats the processes of steps 210 and 220.
If the fuel pressure Pi is higher than the previous fuel pressure P (i-1) in step 220, it is determined that the fuel pressure P is in the process of increasing and the process proceeds to step 230.

In step 230, it is determined whether or not the once-differentiated value (dPi / dti) read this time exceeds a predetermined threshold value d1 on the plus side for a predetermined reference time T1. Here, the first derivative (dPi / dt)
If i) exceeds the threshold value d1 and the reference time T1 has not elapsed, the process jumps to step 210 and repeats the processing of steps 210 to 230. Step 23
At 0, if the one-time differential value (dPi / dti) exceeds the threshold value d1 and the reference time T1 has elapsed, it is determined that the fuel pressure P is in the process of increasing the fuel pressure P to start fuel injection, and step 240 is performed. Move to.

Then, in step 240, RA
The fuel pressure P corresponding to the time ti stored in M83
i (dPi / dti) and the second derivative (d
² Pi / dti ² ).

Next, at step 250, it is determined whether or not the currently read second derivative (d ² Pi / dti ² ) is smaller than a reference value α. Here, if the second derivative (d ² Pi / dti ² ) is not smaller than the reference value α, it is determined that the rate of change of the fuel pressure Pi has not dropped significantly, and the routine jumps to step 240, where it jumps to step 240. Step 250 is repeated. On the other hand, in step 250, the second derivative (d ² Pi / dt)
If i ² ) is smaller than the reference value α, it is determined that the rate of change of the fuel pressure P has greatly decreased during the process of increasing the fuel pressure P, and the routine proceeds to step 260.

Then, in step 260, the once-differentiated value (dPi / dti) read this time falls below a predetermined threshold value d2 on the negative side and a predetermined reference time T2
Is determined. Here, when the one-time differential value (dPi / dti) is less than the threshold value d2 and the reference time T2 has not elapsed, the one-time differential value (dPi / dti) is reduced due to the start of fuel injection. Assuming that no change has occurred, the process jumps to step 240 and repeats the processing of steps 240 to 260. Step 26
At 0, when the one-time differential value (dPi / dti) falls below the threshold value d2 and the reference time T2 has elapsed, the one-time differential value (dPi / dti) due to the start of fuel injection.
Then, the process proceeds to step 270 assuming that the change in the fuel pressure P has definitely decreased.

In step 270, the RAM 83 is traced back to the time ti when the one-time differential value (dPi / dti) becomes "0" from the time when it is determined that the rate of change of the fuel pressure P has surely decreased. Search the stored operation data. Here, the time ti when the one-time differential value (dPi / dti) becomes “0” is the time when the rate of increase of the fuel pressure P first changes from positive to negative during the process of increasing the fuel pressure P. Yes, it is.

Next, in step 280, at the time ti when the one-time differential value (dPi / dti) becomes “0” in the retrieved calculation data, the time ti is determined by the fuel injection nozzle 4 from the fuel injection nozzle 4. Is started, that is, when the needle valve is opened, and the time ti is set as the injection start time ts. Further, the fuel pressure Pi at the time ti is set as the injection start pressure Ps.

Therefore, according to the processing of the "ts, Ps calculation routine" described above, every time one fuel injection is executed, the injection start time ts and the injection start pressure Ps at that time are executed.
Is temporarily stored in the RAM 83.

Here, the injection start time ts, the injection start pressure Ps, the fuel pressure P, and the one-time differential value (dPi / An example of the behavior of dti) will be described with reference to the time chart of FIG.

When the plunger 12 of the fuel injection pump 1 starts to move forward during fuel injection, the fuel pressure P starts increasing at time t1, as shown in FIG. Then, the fuel pressure P is determined by the plunger 12
It gradually increases with the forward movement of. At this time, the one time differential value (dP / dt) of the fuel pressure P changes as shown in FIG. Here, immediately after the time t1, the first derivative (dP
/ Dt) exceeds the threshold value d1 on the positive side and the reference time T
After the elapse of one, the ECU 71 determines that the fuel pressure P is in the process of increasing, which should lead to the start of fuel injection.

Thereafter, at time t2, when the increasing fuel pressure P undergoes a large inflection, its one-time differential value (dP / d
t) falls greatly. Then, immediately after the time t2, when the first derivative (dP / dt) falls below the negative threshold value d2 and the reference time T2 elapses, the ECU 71 sets the fuel pressure P due to the start of fuel injection. It is determined that the change rate has definitely decreased. In the ECU 71,
One-time differential value (dPi / dti) retroactively from the judgment time
Is obtained at time t2 at which becomes “0”, and the time t2 is obtained as the injection start time ts. Further, at time t2
Is obtained as the injection start pressure Ps. That is, as shown in FIG. 7A, the injection start time ts corresponding to the inflection point A where the rate of increase of the fuel pressure P first changes from positive to negative, and the injection start pressure Ps at that time are obtained. .

In this embodiment, the following fuel injection amount control is executed using the injection start pressure Ps at the injection start time ts obtained as described above. That is,
FIG. 9 is a flowchart showing the processing of the "fuel injection amount control routine" performed using the above-described injection start pressure Ps among the processing performed by the ECU 71, and is periodically performed at predetermined intervals.

When the process proceeds to this routine, first, at step 300, the engine speed N obtained from the engine speed sensor 35, the accelerator sensor 73, and the like.
E and the accelerator opening ACCP are read.
Further, the target injection amount Q0 used in the previous fuel injection is read.

Subsequently, in step 310, it is determined whether or not the current operation state of the diesel engine 3 is in the injection amount feedback (FB) execution region. The determination of the injection amount FB execution region is performed with reference to a map predetermined as shown in FIG. 10 based on the relationship between the engine speed NE and the previous target injection amount Q0. That is, in this map, the injection amount FB is set to be in the low-rotation / low-load region. If it is determined in step 310 that the injection amount is in the FB execution region, step 3
Then, the process proceeds to step S <b> 20 to execute the processing of steps 320 to 370.

That is, in step 320, "t
s, Ps calculation routine "and reads and stores the injection start pressure Ps. Also, the injection start pressure Ps
Is set as the actual fuel pressure when the fuel injection nozzle 4 is opened, that is, the actual valve opening pressure Pnr.

Next, at step 330, the actual valve opening pressure Pn is calculated based on the calculated actual valve opening pressure Pnr and the like.
A change amount (remaining fuel amount change amount) Qre of the remaining fuel amount to be changed according to the difference of r is predicted and calculated. The calculation of the residual fuel amount change amount Qre is performed according to the following formula.

Qre = Vi * ε * (Pns−Pnr) = Vi * ε * ΔPn Here, “Vi” means the volume of the fuel system from the fuel injection pump 1 to the fuel injection nozzle 4, and “ε”. Represents the bulk modulus of the fuel, and “Pns” represents the standard valve opening pressure as the reference pressure in the standard state of the fuel injection nozzle 4. Therefore, in the above formula, the residual fuel amount change amount Qre in the fuel system is predicted and calculated based on the valve opening pressure deviation ΔPn which is the difference between the standard valve opening pressure Pns and the actual valve opening pressure Pnr. Here, it is known that the change amount Qre of the residual fuel amount in the fuel system changes due to the difference in the actual valve opening pressure Pnr in the fuel injection nozzle 4. It is also known that the fuel injection amount from the fuel injection nozzle 4 changes due to the difference in the residual fuel amount change amount Qre.

In step 340, a target injection amount Q1 corresponding to the current operating state is calculated based on the engine speed NE, the accelerator opening ACCP, and the like. In this embodiment, the engine rotational speed NE and the accelerator opening AC
The basic injection amount is obtained based on the CP and the like, and the correction injection amount is added to the basic injection amount as necessary, thereby obtaining the target injection amount Q1. Examples of the correction injection amount include a cold correction injection amount obtained based on the cooling water temperature THW.

Further, at step 350, the result obtained by subtracting the currently obtained residual fuel amount change amount Qre from the currently obtained target injection amount Q1 is set as the corrected target injection amount Q for the next fuel injection. . That is, the fuel amount obtained by subtracting the residual fuel amount change amount Qre in the fuel system from the target injection amount Q1 obtained based on the operating state of the diesel engine 3 is obtained as the corrected target injection amount Q.

Then, in step 360, fuel injection is executed based on the corrected target injection amount Q obtained this time. That is, based on the corrected target injection amount Q, the electromagnetic spill valve 2
By controlling 3, the fuel pumping from the fuel injection pump 1 to the fuel injection nozzle 4 is controlled, thereby controlling the fuel injection amount from the fuel injection nozzle 4.

In step 370, the corrected target injection amount Q used for executing the current fuel injection is set as the previous target injection amount Q0, and the subsequent processing is temporarily terminated. Thus, the fuel injection amount control in the injection amount FB execution region is executed.

On the other hand, if it is determined in step 310 that the injection amount is not in the FB execution region, the process proceeds from step 310 to step 380. Then, step 380
In the same manner as in step 340, the target injection amount Q1 corresponding to the current operating state is calculated based on the engine speed NE, the accelerator opening ACCP, and the like.

Subsequently, at step 390, the obtained target injection amount Q1 is set as the corrected target injection amount Q, and the routine proceeds to step 360. And step 3
At 60, the fuel injection is executed based on the corrected target injection amount Q in the same manner as described above. Further, step 370
In, the corrected target injection amount Q used for executing the current fuel injection is set as the previous target injection amount Q0, and the subsequent processing is temporarily ended. Thus, the injection amount FB
The fuel injection amount control in an area other than the execution area is executed.

As described above, according to the fuel injection amount control of this embodiment, when the operation state of the diesel engine 3 is in the injection amount FB execution region, the residual fuel amount change amount Qre in the fuel system is actually measured. Target injection quantity Q to be injected
1 and the fuel injection is executed. That is, when the current fuel injection is executed, the residual fuel amount change amount Qre obtained at the time of the previous fuel injection is obtained based on the actual valve opening pressure Pnr at the fuel injection nozzle 4. Then, the residual fuel amount change amount Qre is subtracted from the target injection amount Q1 obtained according to the operation state at that time, and the subtraction result is obtained as the corrected target injection amount Q. Then, fuel injection is executed based on the corrected target injection amount Q. That is, the target injection amount Q1 is corrected by the residual fuel amount change amount Qre in the fuel system, and the fuel injection amount control is executed. Therefore, in each fuel injection, the amount of fuel pumped from the fuel injection pump 1 to the fuel injection nozzle 4 includes the actual valve opening pressure P of the fuel injection nozzle 4.
The residual fuel amount change amount Qre resulting from the change in nr is considered, and the influence of the residual fuel amount change amount Qre is eliminated. Therefore, even if the actual valve opening pressure Pnr in the fuel injection nozzle 4 changes with time, the desired fuel amount is injected into each cylinder of the diesel engine 3 without being affected by the change. That is, the fuel injection amount control is executed without being affected by the change in the actual valve opening pressure Pnr in the fuel injection nozzle 4. Moreover, in this embodiment, in order to control the fuel injection amount from the fuel injection nozzle 4 to be an injection amount according to the operating state at each time,
Instead of adjusting the valve opening pressure of the fuel injection nozzle 4,
The amount of fuel itself pumped from the fuel injection pump 1 is adjusted.

As a result, without providing special means for adjusting the valve opening pressure in the fuel injection nozzle 4, it is possible to cope with a change in the actual valve opening pressure Pnr caused by a change with time.
Highly accurate fuel injection amount control can be stably performed over a long period of time. As a result, generation of smoke and nitrogen oxides (NOx) from the diesel engine 3 can be suppressed.

In this embodiment, no special means for adjusting the valve opening pressure of the fuel injection nozzle 4 is provided.
The mechanism is not complicated by that much, and there is no need to provide a special control program for the means.

Further, in this embodiment, when determining the actual valve opening pressure Pnr of the fuel injection nozzle 4, the pressure sensor 4
The waveform of the fuel pressure P obtained from 7 is monitored. Further, during the process of increasing the fuel pressure P, the differential value (dPi / d
The point in time when ti) first changes from positive to negative is determined. Here, the first derivative of the fuel pressure P (dPi / dt)
It has been confirmed that the point where i) changes from positive to negative for the first time corresponds to a portion where the fuel pressure P drops momentarily due to the start of fuel injection. The point in time when the first differential value (dPi / dti) of the fuel pressure P changes from positive to negative means that the fuel pressure P has increased to some extent,
First, it has been confirmed that it means the inflection point A at the time of a momentary drop.

Accordingly, the injection start time ts is determined based on the change in the first derivative (dPi / dti) together with the change in the fuel pressure P, and the injection start pressure Ps at that time, that is, the actual valve opening pressure Pnr is determined by the fuel pressure. The inflection point A of P is specifically specified, and the actual valve opening pressure Pnr is eliminated by eliminating the influence of noise and the like.
Is determined.

As a result, the actual valve opening pressure Pnr at the fuel injection nozzle 4 can be obtained more accurately. Therefore, it is possible to more accurately obtain the residual fuel amount change amount Qre obtained based on the actual valve opening pressure Pnr, and thus more accurately obtain the corrected target injection amount Q. In this sense, the fuel injection amount control can be performed with higher accuracy.

In this embodiment, in order to determine the fuel injection start timing from the waveform of the fuel pressure P and its one-time differential value (dPi / dti), the "ts, Ps calculation routine" of FIG. 7 is executed. As described above, the first derivative (d
Pi / dti) exceeds threshold value d1, and it is determined that reference time T1 has elapsed. At the same time, the first derivative (d
Pi / dti) falls below the threshold value d2 and the reference time T2
Is determined to have passed. Therefore, even if the waveform of the fuel pressure P slightly changes due to noise, the change is not erroneously determined as the inflection point A of the fuel pressure P corresponding to the start of fuel injection. Therefore, from this, it is possible to more accurately determine the injection start time ts and the injection start pressure Ps, and thus the actual valve opening pressure Pnr.

(Second Embodiment) Next, a second embodiment in which the fuel injection amount control device for an internal combustion engine according to the present invention is embodied in an electronically controlled diesel engine of an automobile will be described with reference to FIGS. In this embodiment, the configuration of the diesel engine system with a supercharger and the like is assumed to be the same as that of the first embodiment, and the same members are denoted by the same reference numerals and description thereof will be omitted. The following description focuses on points that are particularly different from the first embodiment.

In this embodiment, in addition to detecting the actual valve opening pressure Pnr at the fuel injection nozzle 4, the actual residual pressure Pn in the high pressure chamber 15 of the fuel injection pump 1 during non-injection is obtained.
cr is detected. In this embodiment, the fuel injection pump 1
Is provided with a delivery valve 36 composed of a CPV. The relationship between the stroke of the plunger 12 and the increase in the pressure of the high-pressure chamber 15 changes due to the change over time of the spring constant of the valve 36, and the residual fuel amount change amount Qre Could be affected. Therefore, in this embodiment, the fuel injection amount control is performed on the residual fuel amount change amount Qre in consideration of the actual residual pressure Pcr.

FIG. 12 shows a schematic configuration of a supercharged diesel engine system according to this embodiment. Unlike the first embodiment, the high pressure chamber 15 of the fuel injection pump 1 is different from the first embodiment.
And the pump housing 13 has another pressure sensor 7
8 are provided. This pressure sensor 78 is connected to the high pressure chamber 15.
And outputs a signal corresponding to the magnitude of the detected value. The ECU 71 includes sensors 72 to 77, a rotation speed sensor 35, and a pressure sensor 47.
In addition, another pressure sensor 78 is connected respectively. In addition, the ECU 71 controls the sensors 35, 47, 72 to 78.
Spill valve 23, T based on each signal output from
CV33, glow plug 46, EVRV58 and each VS
V64, 65, etc. are suitably controlled.

Next, the processing operation for controlling the fuel injection amount executed by the ECU 71 will be described with reference to FIGS. FIG. 13 shows a “subroutine” executed at each time ti measured by the timer function of the CPU 81 among the processes executed by the ECU 71.
6 is a flowchart showing the processing of FIG.

When the process proceeds to this routine, first, at step 410, the fuel pressure P and the high pressure chamber pressure P0 are sampled based on the signals from the pressure sensor 47 and the pressure sensor 78, respectively.

Subsequently, at step 420, the fuel pressure Pi at the time ti at that time is calculated. Then
In step 430, the one-time differential value (dPi / dt) as the rate of change of the fuel pressure Pi at the time ti at that time.
i) is calculated. Further, in step 440, a second derivative (d ² Pi / dti ² ) corresponding to the change in the change rate of the fuel pressure Pi at the time ti at that time is calculated.

In step 450, the high pressure chamber pressure P0i at the time ti at that time is calculated. Then
In step 460, the one-time differential value (dP0i) as the rate of change of the high-pressure chamber pressure P0i at the time ti at that time.
/ Dti).

In step 470, the fuel pressure Pi determined this time and the one-time differential value (dPi / dt)
i) and the second derivative (d ² Pi / dti ² ) at time ti
Are respectively stored in the RAM 83 as calculation data corresponding to.

In step 480, the high pressure chamber pressure P0i obtained this time and its one-time differential value (dP0i
/ Dti) is stored in the RAM 83 as calculation data corresponding to the time ti, and the subsequent processing is temporarily terminated.

Therefore, according to the above-described "subroutine", the fuel pressure Pi corresponding to each time ti and the one-time differential value (dPi / dti) each time one fuel injection is executed.
And the second derivative (d ² Pi / dti ² ) are sequentially stored in the RAM 83 as calculation data. together,
The high pressure chamber pressure P0i corresponding to each time ti and its one-time differential value (dP0i / dti) are sequentially stored in the RAM 83 as calculation data.

In this embodiment, similarly to the first embodiment, the ECU 71 calculates the injection start pressure Ps at the injection start time ts used for controlling the fuel injection amount. Here, the processing content for the calculation is the first
“T” shown in the flowchart of FIG. 7 described in the embodiment.
The description is omitted because it is the same as that of the “s, Ps calculation routine”.

On the other hand, in this embodiment, the actual residual pressure Pcr used for controlling the fuel injection amount is calculated. FIG. 14 is a flowchart showing the processing of a “Pcr calculation routine” for calculating the actual residual pressure Pcr among the processings executed by the ECU 71.
This is performed each time the injection start time ts is obtained in the processing of the “s, Ps calculation routine”.

When the process proceeds to this routine, at step 510, the high-pressure chamber pressure P
The high pressure chamber pressure P0i stored in the RAM 83 is searched by going back to the time ti when the first differential value of 0 (dP0i / dti) becomes “0”. Here, the first derivative (dP0i
/ Dti) is high pressure chamber pressure P0i at time ti when it becomes “0”
Is equivalent to the pressure immediately before the plunger 12 starts going forward.

Then, in step 520, the high pressure chamber pressure P0i at time ti when the one-time differential value (dP0i / dti) becomes "0" is set as the actual residual pressure Pcr corresponding to the high pressure chamber pressure P0i during non-injection. Is set, and the subsequent processing ends once.

Here, the high-pressure chamber pressure P0 and its one-time differential value (d
The behavior of (P0 / dt) is shown in the time chart of FIG. In the figure, time t2 is the injection start time ts
At the time t1 when the one-time differential value (dP0 / dt) becomes “0” retroactively from the injection start time ts.
Is required. Then, the high pressure chamber pressure P0 at the time t1
Is obtained as the actual residual pressure Pcr.

Since the high-pressure chamber 15 and the fuel injection valve 4 constitute one fuel system, the behavior of the high-pressure chamber pressure P0 and the behavior of the fuel pressure P are similar but different in absolute value. Become. Similarly, the behavior of the first derivative (dP0 / dt) of the high pressure chamber pressure P0 and the behavior of the first derivative (dP / dt) of the fuel pressure P are similar.

Therefore, according to the processing of the "Pcr calculation routine", the actual residual pressure Pcr at that time is temporarily stored in the RAM 83 every time one fuel injection is executed.
In this embodiment, the following fuel injection amount control is executed using the injection start pressure Ps and the actual residual pressure Pcr obtained as described above. FIG. 16 shows the ECU 7
1 is a flowchart illustrating a process of a “fuel injection amount control routine” performed using the above-described injection start pressure Ps and actual residual pressure Pcr, among the processes executed by the fuel injection control unit 1;
It is executed periodically at predetermined intervals. Note that the processing content of the "fuel injection amount control routine" of this embodiment is basically the same as that of FIG. 9 described in the first embodiment. Only different parts related to the calculation will be described.

That is, the routine shown in FIG. 16 is particularly different in the processing of steps 604 and 605. Then, in the case where the diesel engine 3 is in the operating state in the injection amount FB execution region, in step 604, “Pc
The actual residual pressure Pcr obtained in the “r calculation routine” is read.

In step 605, a residual fuel amount change amount Qre to be changed according to the difference between the actual valve opening pressure Pnr and the actual residual pressure Pcr obtained this time is predicted and calculated. The calculation of the residual fuel amount change amount Qre is performed according to the following formula.

Qre = Vi * ε * (Pns−Pnr) −Vi * εc * (Pcs−Pcr) = Vi * ε * ΔPn−Vi * εc * ΔPc = Vi (ε * ΔPn−εc * ΔPc) The newly written “εc” means the bulk modulus of the fuel near the actual residual pressure Pcr, and “Pcs” means the standard residual pressure as the high-pressure chamber pressure P0 in the standard state at the time of non-injection. .

Accordingly, in the above formula, the valve opening pressure deviation ΔΔ, which is the difference between the standard valve opening pressure Pns and the actual valve opening pressure Pnr.
Based on Pn and a residual pressure deviation ΔPc which is a difference between the standard residual pressure Pcs and the actual residual pressure Pcr, a residual fuel amount change amount Qre in the fuel system is predicted and calculated.

As described above, according to the fuel injection amount control of this embodiment, when the operating state of the diesel engine 3 is in the injection amount FB execution region, the residual fuel amount change amount Qre in the fuel system is actually calculated. The fuel injection is executed by feeding back to the target injection amount Q1 to be injected. That is, at the time of the current fuel injection, the amount of change in the residual fuel amount Qre at the time of the previous fuel injection is determined by the actual valve opening pressure Pn
r and the actual residual pressure Pcr at the fuel injection pump 1. Then, based on the corrected target injection amount Q obtained by subtracting the residual fuel amount change amount Qre from the target injection amount Q1, the fuel injection amount control is executed.

Therefore, in this embodiment, as in the case of the first embodiment, the actual valve opening pressure Pn
The fuel injection amount control is executed without being affected by the change in r. In addition, in this embodiment, even if the actual residual pressure Pcr in the fuel injection pump 1 changes from the standard residual pressure Pcs due to a change with time of the delivery valve 36, the desired residual pressure Pcr is not affected by the change. Is injected from the fuel injection nozzle 4. That is, the fuel injection amount control is executed without being affected by the change in the actual residual pressure Pcr in the fuel injection pump 1.

As a result, the difference between the actual valve opening pressure Pnr and the difference between the actual residual pressure Pcr due to aging can be dealt with without providing any special means for adjusting the valve opening pressure in the fuel injection nozzle 4. Thus, more accurate fuel injection amount control can be stably performed over a long period of time. As a result, smoke and NO from the diesel engine 3
The occurrence of x can be suppressed.

The other actions and effects of this embodiment can be the same as those of the first embodiment. (Third Embodiment) Next, a third embodiment in which the fuel injection amount control device for an internal combustion engine according to the present invention is embodied in an electronically controlled diesel engine of an automobile will be described with reference to FIGS. In this embodiment, the configuration of the diesel engine system with a supercharger and the like is assumed to be the same as that of the first embodiment, and the same members are denoted by the same reference numerals and description thereof will be omitted. The following description focuses on points that are particularly different from the first embodiment.

In this embodiment, in addition to detecting the actual valve opening pressure Pnr at the fuel injection nozzle 4, the fuel temperature THF at the fuel injection pump 1 is detected. In the fuel injection pump 1, since the bulk elastic modulus of the fuel changes due to the difference in the internal fuel temperature THF, there is a possibility that the change amount Qre of the residual fuel amount changes due to the difference in the bulk elastic modulus. Therefore, in this embodiment, the fuel injection amount control is further performed on the residual fuel amount change amount Qre in consideration of the fuel temperature THF.

FIG. 17 shows a schematic configuration of a diesel engine system with a supercharger according to this embodiment. Unlike the first embodiment, a fuel temperature sensor 79 is provided in the pump housing 13 of the fuel injection pump 1. ing. The fuel temperature sensor 79 detects the temperature of the fuel filling the fuel chamber 21, that is, the fuel temperature THF, and outputs a signal corresponding to the magnitude of the detected value. The ECU 71 includes sensors 72 to 77, a rotation speed sensor 35, and a pressure sensor 47.
In addition, a fuel temperature sensor 79 is connected.
In addition, the ECU 71 controls the sensors 35, 47, 72 to 77, 7
9, the electromagnetic spill valve 23,
TCV33, glow plug 46, EVRV58 and each V
SV64, 65, etc. are suitably controlled.

Next, the processing operation for controlling the fuel injection amount executed by the ECU 71 will be described with reference to FIGS. In this embodiment, the ECU
71, the injection start time ts
The processing contents of the “subroutine” and the “ts, Ps calculation routine” used to determine the injection start pressure Ps are the same as those in FIGS. 6 and 7 described in the first embodiment. Description is omitted.

Therefore, also in this embodiment, the injection start time ts and the injection start pressure Ps are obtained based on the fuel pressure P detected by the pressure sensor 47.
Then, in this embodiment, the following fuel injection amount control is executed using the obtained injection start time ts and injection start pressure Ps.

FIG. 18 shows the injection start time ts and the injection start pressure P among the processes executed by the ECU 71.
5 is a flowchart illustrating a process of a “fuel injection amount control routine” performed using s, which is periodically executed at predetermined intervals. Note that the processing content of the “fuel injection amount control routine” in this embodiment is the same as that in FIG.
This is basically the same as that of the first embodiment, and here, only the different portions in relation to the calculation of the residual fuel amount change amount Qre will be described.

That is, in the routine shown in FIG. 18, the processing of steps 704, 705, and 706 is particularly different.
Then, when the diesel engine 3 is in the operating state of the injection amount FB execution region, in step 704, the fuel temperature THF is read based on the signal from the fuel temperature sensor 79. In step 705, a bulk modulus of the fuel at the fuel temperature THF, that is, an actual bulk modulus εtr is calculated based on the read fuel temperature THF. The calculation of the actual bulk modulus εtr is performed with reference to a map in which the relationship between the fuel temperature THF and the actual bulk modulus εtr as shown in FIG. 19 is predetermined.

In step 706, a residual fuel amount change amount Qre to be changed according to the difference between the actual valve opening pressure Pnr and the actual bulk modulus εtr obtained this time is predicted and calculated. The calculation of the residual fuel amount change amount Qre is performed according to the following formula.

Qre = Vi * (εts * Pns−εtr * Pnr) Here, “εts” newly written means a standard bulk modulus at a standard fuel temperature THF.

Accordingly, in the above formula, the difference between the standard valve opening pressure Pns corrected based on the standard bulk modulus εts and the actual valve opening pressure Pnr corrected based on the actual volume modulus εtr is used in the fuel system. The residual fuel amount change amount Qre is predicted and calculated.

As described above, according to the fuel injection amount control of this embodiment, when the operation state of the diesel engine 3 is in the injection amount FB execution range, the residual fuel amount change amount Qre in the fuel system is actually calculated. The fuel injection is executed by feeding back to the target injection amount Q1 to be injected. That is, at the time of the current fuel injection, the amount of change in the residual fuel amount Qre at the time of the previous fuel injection is determined by the actual valve opening pressure Pn
r, and the actual bulk modulus εtr of the fuel, which differs depending on the fuel temperature THF in the fuel injection pump 1. Then, based on the corrected target injection amount Q obtained by subtracting the residual fuel amount change amount Qre from the target injection amount Q1, the fuel injection amount control is executed.

Therefore, in this embodiment, the actual valve opening pressure Pn at the fuel injection nozzle 4 is the same as in the first embodiment.
The fuel injection amount control is executed without being affected by the change in r. In addition, in this embodiment, even if the actual bulk modulus εtr of the fuel changes from the standard bulk modulus εts due to the difference in the fuel temperature THF in the fuel injection pump 1, the change is not affected by the change. The desired fuel amount is injected from the fuel injection nozzle 4. That is, the fuel injection amount control is executed without being affected by the change in the actual bulk modulus εtr of the fuel.

As a result, the difference in the actual valve opening pressure Pnr and the difference in the actual bulk modulus εtr caused by the aging can be dealt with without providing any special means for adjusting the valve opening pressure in the fuel injection nozzle 4. Thus, more accurate fuel injection amount control can be stably performed over a long period of time. As a result, smoke from the diesel engine 3 and N
Ox generation can be suppressed.

Further, as other functions and effects of this embodiment, the same ones as those of the first embodiment can be obtained. The present invention is not limited to the above embodiments, but may be implemented as follows, with a part of the configuration being appropriately changed without departing from the spirit of the invention.

(1) In the first embodiment, the amount of change in the residual fuel amount Qre was obtained according to a calculation formula such as Qre = Vi * ε * (Pns−Pnr) = Vi * ε * ΔPn. On the other hand, the residual fuel amount variation Qre can be obtained by referring to a map in which the relationship between the residual fuel amount variation Qre and the valve opening pressure deviation ΔPn as shown in FIG. 11 is predetermined.

(2) In the second embodiment, the amount of change in the amount of residual fuel Qre was determined according to a calculation formula such as Qre = Vi (ε * ΔPn−εc * ΔPc). On the other hand, the correction amount of the residual fuel amount for the valve opening pressure deviation ΔPn is obtained by referring to the map, and the correction amount of the residual fuel amount for the residual pressure deviation ΔPc is obtained by referring to the map. It is also possible to obtain the residual fuel amount variation Qre by making a correction.

(3) In the third embodiment, the amount of change in the residual fuel amount Qre was determined according to a calculation formula such as Qre = Vi * (εts * Pns−εtr * Pnr). On the other hand, the residual fuel amount change amount Qre can be obtained by using a calculation formula of Qre = Kε * (ΔPn + β * ΔPn-βPns).
In this calculation formula, “Kε” means a constant corresponding to the volume volume of the fuel system, “β” means a coefficient obtained by referring to a map as shown in FIG. 20 based on the fuel temperature THF, and “ “βPns” means the corrected standard valve opening pressure obtained by referring to the map shown in FIG.

Alternatively, the amount of change in the residual fuel amount Qre can be obtained by using a calculation formula of Qre = Kε * Ct.
In this calculation formula, “Ct” means a coefficient obtained by referring to a map as shown in FIG. 22 based on the fuel temperature THF.

(4) In each of the above embodiments, the actual valve opening pressure Pn
Although the pressure sensor 47 for detecting r is provided in each fuel injection nozzle 4 of each cylinder, the pressure sensor is provided in the middle of the fuel pipe leading to each fuel injection nozzle, or in the high pressure chamber 15 of the fuel injection pump. It can also be provided correspondingly.

(5) In each of the above-described embodiments, when the corrected target injection amount Q is obtained, the residual fuel amount change amount Q in the fuel system is calculated from the target injection amount Q1 obtained according to the operating state.
re was deducted. On the other hand, the corrected target injection amount Q may be obtained by adding the residual fuel amount change amount Qre to the target injection amount Q1. In particular,
If the valve opening pressure becomes higher than an expected set value due to a manufacturing error of the fuel injection nozzle 4, the actual injection amount may decrease. Correction for adding the fuel amount change amount Qre is also required.

(6) In each of the above embodiments, when the operation state of the diesel engine 3 is not in the injection amount FB execution region, the target injection amount Q1 simply obtained according to the operation state is set as the corrected target injection amount Q. I did it. On the other hand, when it is not in the injection amount FB execution region, the target injection amount Q1 is corrected based on the learned value of the residual fuel amount change amount Qre learned in advance, and the correction result is set as the corrected target injection amount Q. You can also.

(7) In the above embodiments, the diesel engine 3 as the internal combustion engine is embodied. However, the present invention is not limited to the diesel engine as long as it is an internal combustion engine having a fuel injection pump and a fuel injection nozzle.

[0122]

As described above in detail, according to the present invention, the amount of fuel pumped from fuel injection pump to the fuel injection nozzle, the change in the residual fuel amount caused by a change in the opening pressure Is considered and is not affected by changes in the valve opening pressure.
The desired amount of fuel is injected from the fuel injection nozzle. As a result, high-precision fuel injection amount control can be performed without any special means for adjusting the valve opening pressure at the fuel injection nozzle, without dealing with changes in valve opening pressure due to aging or manufacturing errors. Can be stably realized over a long period of time.

[Brief description of the drawings]

FIG. 1 is a conceptual configuration diagram illustrating a basic conceptual configuration of the present invention.

FIG. 2 is a schematic configuration diagram showing a supercharged diesel engine system according to a first embodiment of the present invention.

FIG. 3 is a sectional view showing a distribution type fuel injection pump in the first embodiment.

FIG. 4 is a diagram showing a pressure sensor provided in a fuel injection nozzle in the first embodiment.

FIG. 5 is a block diagram showing a configuration of an ECU in the first embodiment.

FIG. 6 is a flowchart showing processing of a “subroutine” executed by an ECU in the first embodiment.

FIG. 7 is a flowchart illustrating processing of a “ts, Ps calculation routine” executed by the ECU in the first embodiment.

FIG. 8 is a time chart illustrating behaviors of an injection start time, an injection start pressure, a fuel pressure, and a one-time differential value obtained in one fuel injection in the first embodiment.

FIG. 9 is a flowchart showing a process of a “fuel injection amount control routine” executed by an ECU in the first embodiment.

FIG. 10 is a map in which an injection amount FB execution region is determined in advance from a relationship between an engine rotation speed and a previous target injection amount in the first embodiment.

FIG. 11 In another embodiment of the present invention,
This is a map which is referred to in a modification of the method of calculating the amount of change in residual fuel amount in the first embodiment, and in which the relationship between the amount of change in residual fuel amount and the valve opening pressure deviation is determined in advance.

FIG. 12 is a schematic configuration diagram showing a supercharged diesel engine system according to a second embodiment of the present invention.

FIG. 13 is a flowchart showing a “subroutine” process executed by the ECU in the second embodiment.

FIG. 14 is a flowchart illustrating a process of a “Pcr calculation routine” executed by the ECU in the second embodiment.

FIG. 15 is a time chart for explaining the behavior of the actual residual pressure, the high-pressure chamber pressure, and its one-time differential value obtained in one fuel injection in the second embodiment.

FIG. 16 is a flowchart illustrating a process of a “fuel injection amount control routine” executed by the ECU in the second embodiment.

FIG. 17 is a schematic configuration diagram showing a supercharged diesel engine system according to a third embodiment of the present invention.

FIG. 18 is a flowchart illustrating processing of a “fuel injection amount control routine” executed by the ECU in the third embodiment.

FIG. 19 is a map used for calculating the amount of change in the amount of residual fuel in the third embodiment and in which the relationship between the actual bulk modulus and the fuel temperature is predetermined.

FIG. 20 shows another embodiment of the present invention.
This is a map which is referred to in a modification of the method for calculating the amount of change in the residual fuel amount in the third embodiment and in which the relationship between a predetermined coefficient and the fuel temperature is predetermined.

FIG. 21 is a diagram showing the relationship between the corrected standard valve opening pressure and the fuel temperature, which is referred to in a modification of the method for calculating the amount of change in the residual fuel amount in the third embodiment. is there.

FIG. 22 is a map which is referred to in a modification of the method for calculating the amount of change in the residual fuel amount in the third embodiment, and in which the relationship between a predetermined coefficient and the fuel temperature is predetermined in another embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Fuel injection pump, 3 ... Diesel engine as internal combustion engine, 4 ... Fuel injection nozzle, 47 ... Pressure sensor as valve opening pressure detecting means, 71 ... Valve opening pressure deviation calculating means,
ECUs constituting the residual fuel amount change amount calculation means, the corrected target injection amount calculation means, and the pump control means, 78: pressure sensor, 79: fuel temperature sensor.

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Kazuhiro Iwahashi 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation (72) Inventor Shinji 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation ( 56) References JP-A-4-203441 (JP, A) JP-A-4-203452 (JP, A) JP-A-62-186034 (JP, A) JP-A-64-47944 (JP, U) ) Field surveyed (Int. Cl. ⁷ , DB name) F02D 41/04 F02D 41/38 F02M 65/00

Claims (1)

(57) [Claims] 1. A detecting means for detecting a fuel pressure when a fuel injection nozzle is opened as a valve opening pressure, which is used in an internal combustion engine configured to pump fuel from a fuel injection pump to a fuel injection nozzle. And the fuel caused by the change in the valve opening pressure based on the detection result of the detection means.
In the fuel system from the injection pump to the fuel injection nozzle
And a control means for calculating a target injection amount for fuel injection in consideration of a change in the residual fuel amount in the internal combustion engine, and controlling driving of the fuel injection pump based on the calculation result.