JPH07119516A - Fuel injection device for internal combustion engine - Google Patents

Abstract

PURPOSE:To grasp proper fuel forcibly feeding condition at all times so as to attempt rationalization of fuel injection by coping with secular change and/or fuel property change, in a fuel system in the case of fuel injection device. CONSTITUTION:A pressure sensor is provided on the fuel injection nozzle 4 of an engine so as to detect fuel pressure in a fuel system from a fuel injection pump 1 and the fuel injection nozzle 4. A fuel temperature sensor is provided on the fuel injection pump 1. In an ECU 71, an average fuel pressure change rate is calculated on the basis of the detected value of a pressure sensor 47 during a period from forcibly feed starting of fuel to injection starting, and a fuel volume elastic rate is calculated on the basis of the detected value of the fuel temperature sensor. In the ECU 71, an injection timing command value and a spill timing command value are corrected by a fuel leakage rate found out on the basis of an average fuel pressure change rate and the fuel volume elastic rate. Therefore, secular change and fuel property change in a fuel system are reflected properly on the injection timing command value and the spill timing command value.

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 an internal combustion engine equipped with a fuel injection pump for injecting fuel into the internal combustion engine, a fuel injection nozzle and the like.

[0002]

2. Description of the Related Art Conventionally, in a fuel injection device for an internal combustion engine equipped with a fuel injection pump and a fuel injection nozzle, various types of fuel injection devices are required to match the fuel injection amount and the fuel injection timing from the fuel injection nozzle with a target value. Fuel injection control is being performed.

For example, in an electronically controlled diesel engine, the lift of the plunger in the fuel injection pump causes the fuel in the high pressure chamber to be pumped to the fuel injection nozzle and injected into each cylinder of the engine. Then, the spill ring, spill valve, etc. provided in the fuel injection pump are drive-controlled by the actuator so that the fuel injection amount at that time becomes the target injection amount determined according to the operating state of the engine. By this control, the high pressure chamber of the plunger is opened to the fuel chamber, and a part of the fuel in the high pressure chamber overflows (spills) to the fuel chamber. As a result, the end of pumping of fuel from the fuel injection pump to the fuel injection nozzle, that is, the end timing (fuel injection amount) of fuel injection from the fuel injection nozzle to each cylinder is controlled. Alternatively, the timer device provided in the fuel injection pump is drive-controlled so that the fuel injection timing becomes the target injection timing determined according to the operating state of the engine. By this control, the reciprocating timing of the plunger is adjusted, and the timing of the pressure feed of fuel from the fuel injection pump to the fuel injection nozzle, and by extension, the fuel injection start timing (fuel injection timing) at the fuel injection nozzle is retarded or advanced. Controlled to the side.

However, even in the electronically controlled diesel engine as described above, there are changes with time and changes in fuel properties in the fuel system from the fuel injection pump to the fuel injection nozzle. In particular, the fuel injection pump is provided with a cam plate and a cam roller which are in contact with each other to operate the plunger. Therefore, the fuel injection amount and the fuel injection timing will deviate from the desired values unless the change with time such as wear due to the contact between the cam plate and the cam roller and the change in fuel property are taken into consideration. As a result, smoke and nitrogen oxide (NOx) emissions from the engine may increase.

In view of the above problems, a technique for extending the life of the fuel injection pump by coping with the wear of the cam plate and the cam roller is disclosed in Japanese Patent Laid-Open No. 61-283.
No. 759 is disclosed. That is, in this conventional technique, the parts such as the cam roller that come into contact with the cam plate (cam disk) of the fuel injection pump are made of sialon ceramics having excellent wear resistance.

[0006]

However, in the above-mentioned prior art, although the wear between the cam plate and the cam roller is improved, it is difficult to completely eliminate the wear between the cam plate and the cam roller as long as they are in contact with each other. there were. Therefore, after the fuel injection pump has been used for a long period of time, unavoidable wear occurs between the cam plate and the cam roller, the lift amount of the plunger changes, and the fuel is pumped from the fuel injection pump to the fuel injection nozzle. The state changes. as a result,
There is a possibility that the fuel injection control may be deteriorated and various inconveniences may be caused. Further, the fuel properties including the fuel viscosity and the like change with the lapse of time after the engine is started, but the prior art has not taken this into consideration. Therefore, also from that point of view, there is a possibility that the state of pressure-feeding of the fuel from the fuel injection pump to the fuel injection slur changes and the accuracy of fuel injection control deteriorates.

The present invention has been made in view of the above-mentioned circumstances, and an object thereof is to constantly pressurize the fuel in order to cope with changes over time and changes in fuel properties in the fuel system to optimize fuel injection. An object of the present invention is to provide a fuel injection device for an internal combustion engine that enables the state to be grasped with high accuracy.

[0008]

In order to achieve the above object, according to the present invention, as shown in FIG. 1, a fuel injection nozzle M2 for injecting fuel into an internal combustion engine M1 by being opened by fuel pressure. A fuel injection pump M3 for pumping fuel to the fuel injection nozzle M2; and a fuel pressure detection means M for detecting the fuel pressure in the fuel system M4 from the fuel injection pump M3 to the fuel injection nozzle M2.
5 and the fuel for calculating the rate of change of the fuel pressure based on the detection result of the fuel pressure detection means M5 between the start of the pressure feed of the fuel pressure-fed from the fuel injection pump M3 to the fuel injection nozzle M2. Pressure change rate calculation means M6, fuel state detection means M7 for detecting the state of fuel, and fuel volume elastic modulus calculation for calculating the volume elastic modulus of fuel based on the detection results of the fuel state detection means M7. Means M8
And a calculation result of the fuel pressure change rate calculation means M6 and a calculation result of the fuel volume elastic modulus calculation means M8, for calculating the pressure-feeding state value of the fuel pressure-fed from the fuel injection pump M3 to the fuel injection nozzle M2. Fuel pressure feeding state value calculation means M9
The purpose is to have and.

[0009]

Therefore, according to the above construction, as shown in FIG. 1, every time the fuel is injected from the fuel injection nozzle M2, the fuel pressure in the fuel system M4 is detected by the fuel pressure detecting means M5, and the fuel pressure is detected. The state of the fuel is detected by the state detecting means M7. Further, in the fuel pressure change rate calculation means M6,
The rate of change in fuel pressure is calculated based on the fuel pressure detected as described above. Further, the fuel volume elastic modulus calculation means M
In 8, the bulk modulus of the fuel is calculated based on the fuel state detected as described above. Then, the fuel pressure feeding state value calculating means M9 calculates the fuel pressure feeding state value in the fuel system M4 based on the fuel pressure change rate and the fuel volume elastic modulus calculated as described above. Therefore, the fuel pressure-feeding state value that properly reflects changes over time in the fuel system M4, changes in fuel properties, and the like is always obtained.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the fuel injection device for an internal combustion engine according to the present invention is embodied in an electronically controlled diesel engine for an automobile will be described in detail below with reference to FIGS.

FIG. 2 shows a schematic structure of a diesel engine system with a supercharger in this embodiment, and FIG. 3 shows the distribution type fuel injection pump 1. Fuel injection pump 1
Is provided with a drive pulley 2, and the drive pulley 2 is drivingly connected to a crankshaft 40 of a diesel engine 3 as an internal combustion engine via a belt or the like.
The drive shaft 2 is driven by the crankshaft 40.
Is rotated and the fuel injection pump 1 is driven, so that fuel is pressure-fed to the fuel injection nozzle 4 provided for each cylinder (four cylinders in this embodiment) of the diesel engine 3 through the fuel pipe 4a.

In this embodiment, the fuel injection nozzle 4 is an automatic valve having a built-in needle valve and a spring for adjusting the valve opening pressure of the needle valve. The valve is opened. Therefore, the fuel pressure-fed from the fuel injection pump 1 applies the fuel pressure P of a predetermined level or higher to the fuel injection nozzle 4, so that the fuel is injected from the nozzle 4 to the diesel engine 3.

The fuel injection pump 1 has a drive shaft 5
Is provided, and the drive pulley 2 is attached to the tip of the drive shaft 5. A fuel feed pump (developed by 90 degrees in this figure) 6 made up of a vane type pump is provided in the middle of the drive shaft 5. A disc-shaped pulsar 7 is attached to the base end side of the drive shaft 5. On the outer peripheral surface of the pulsar 7, the same number as the number of cylinders of the diesel engine 3, that is, four teeth in this embodiment (a total of "eight") are formed at equal angular intervals. Also, between each missing tooth,
Fourteen protrusions (“56” in total) 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 8a are provided in the same number as the number of cylinders of the diesel engine 3. Also, the cam plate 8 is the spring 1
It is urged by 1 to engage the cam roller 10.

A proximal end of a fuel pressurizing plunger 12 is integrally rotatably attached to the cam plate 8. 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 is rotated while being engaged with the cam roller 10. As a result, the cam plate 8 is reciprocated in the left-right direction in the drawing as many times as the number of cylinders while being rotated, and accordingly, the plunger 12 is reciprocated in the same direction while being rotated. That is, the cam face 8 a is the cam roller 1 of the roller ring 9.
Plunger 12 moves forward (lift) in the process of climbing to 0
To be done. On the contrary, the cam face 8a has the cam roller 1
Plunger 12 returns (down) in the process of getting over 0
To be done.

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

In the pump housing 13 of this embodiment, the delivery valve 3 formed of a constant pressure valve (CPV) is provided on the outlet side of each distribution passage 18.
6 is provided. The delivery valve 36 is for preventing the reverse flow of the fuel pressure-fed from the distribution passage 18 to the fuel pipe 4a, and is opened when the fuel pressure P of a certain level or higher is obtained.

Then, the drive shaft 5 is rotated and the fuel feed pump 6 is driven, so that fuel is introduced into the fuel chamber 21 from the fuel tank (not shown) through the fuel supply port 20. Further, in the suction stroke in which the plunger 12 is returned and the high pressure chamber 15 is depressurized, the suction groove 1
The fuel is introduced from the fuel chamber 21 to the high-pressure chamber 15 by communicating one of the six with the suction port 19. On the other hand, in the compression stroke in which the plunger 12 is moved forward and the high pressure chamber 15 is pressurized, fuel is pressure-fed and injected from the distribution passage 18 to the fuel injection nozzle 4 of each cylinder through the fuel pipe 4a.

In the pump housing 13, the high pressure chamber 1
A spill passage 22 for spilling fuel is formed between the fuel cell 5 and the fuel chamber 21. An electromagnetic spill valve 23 is provided in the spill passage 22. The electromagnetic spill valve 23 is opened and closed to adjust the spill of fuel from the high pressure chamber 15. Electromagnetic spill valve 23
Is a normally open valve, and when the coil 24 is in a non-energized (off) state, the spill passage 22 is opened, that is, opened by the valve body 25, and the fuel in the high pressure chamber 15 is spilled to the fuel chamber 21. It On the other hand, when the coil 24 is energized (turned on), the spill passage 22 is closed or closed by the valve body 25, and the spill of fuel from the high pressure chamber 15 to the fuel chamber 21 is blocked.

Therefore, the electromagnetic spill valve 23 is controlled to be turned on / off by energization, so that the valve 23 is controlled to be closed / opened, and the spill of fuel from the high pressure chamber 15 to the fuel chamber 21 is adjusted. The electromagnetic spill valve 23 is opened during the compression stroke of the plunger 12, so that the high pressure chamber 1
The fuel in 5 is decompressed and the fuel injection from the fuel injection nozzle 4 is stopped. That is, even if the plunger 12 is moving forward, while the electromagnetic spill valve 23 is open,
The fuel pressure in the high pressure chamber 15 does not rise, and the fuel injection nozzle 4
Fuel is not injected from. Further, the opening timing of the electromagnetic spill valve 23 is controlled during the forward movement of the plunger 12, so that 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. .

A timer device (developed by "90 degrees" in this figure) 26 for controlling the fuel injection timing to the advance side or the retard side is provided below the pump housing 13. . The timer device 26 changes the time when the cam face 8a engages the cam roller 10, that is, the time when the plunger 12 reciprocates by changing the rotational position of the roller ring 9 with respect to the rotational direction of the drive shaft 5. 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, in the timer housing 27, a low pressure chamber 29 and a pressurizing chamber 30 are formed on both sides of the timer piston 28, respectively. Then, in the low pressure chamber 29, the timer piston 28
Spring 3 for urging the pressurizing chamber 30 into the pressurizing chamber 30
1 is provided. Further, the timer piston 28 is connected to the roller ring 9 via a slide pin 32.

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

The fuel pressure inside the fuel injection pump 1 is used as the control hydraulic pressure of the timer device 26. The timer device 26 is provided with a timer control valve (TCV) 33 for adjusting the fuel pressure. That is, the communication passage 34 is provided between the pressurizing chamber 30 and the low pressure chamber 29 of the timer housing 27.
TCV33 is provided on the way. The TCV 33 is a solenoid valve whose opening is controlled by a duty-controlled energizing signal, and the fuel pressure in the pressurizing chamber 30 is adjusted by controlling the opening of the TCV 33. Then, by adjusting the fuel pressure, the reciprocating timing of the plunger 12 is controlled, so that the fuel injection nozzle 4
The fuel injection timing from is controlled to the advance side or the retard side.

A rotation speed sensor 35 composed of an electromagnetic pickup coil is mounted above the roller ring 9 so as to face the outer peripheral surface of the pulsar 7. This rotation speed sensor 35
Detects the passage of the pulsar 7 when it is traversed by the protrusion of the pulsar 7 and outputs it 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, as a reference position signal, an engine rotation pulse signal corresponding to a constant crank angle due to the missing tooth of the pulsar 7. Further, the rotation speed sensor 35 outputs a series of engine rotation pulse signals as a signal for obtaining the engine rotation speed NE.
Since the rotation speed sensor 35 is integrated with the roller ring 9, it is possible to output a reference engine rotation pulse signal with respect to the reciprocating movement of the plunger 12 at a constant timing regardless of the control operation of the timer device 26. .

In addition, the pump housing 13 has a fuel temperature sensor 37 as a fuel state detecting means for detecting the temperature of the fuel contained in the fuel chamber 21, that is, the fuel temperature THF. It is provided.

Next, the diesel engine 3 will be described. In FIG. 2, in the diesel engine 3, a main combustion chamber 44 corresponding to each cylinder is formed by the cylinder bore 41, the piston 42, and the cylinder head 43. Further, the cylinder head 43 is formed with auxiliary combustion chambers 45 communicating with the respective main combustion chambers 44. Then, the fuel is injected from each fuel injection nozzle 4 into each auxiliary combustion chamber 45. Each sub-combustion chamber 45 is provided with a well-known glow plug 46 as a starting 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 fuel pressure detecting means. The pressure sensor 47 detects the pressure of fuel in the fuel system from the fuel injection pump 1 to each fuel injection nozzle 4, that is, the fuel pressure P, and outputs a signal according to the magnitude of the detected value.

On the other hand, the diesel engine 3 is provided with an intake passage 49 and an exhaust passage 50 which communicate with each cylinder. Further, the intake passage 49 is provided with a compressor 52 of a turbocharger 51 that constitutes a supercharger,
The exhaust passage 50 has a turbine 53 of a turbocharger 51.
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 the compressor 52 coaxially with the turbine 53 to rotate the pressure of the intake air. Then, by boosting the pressure of the intake air, high-density air is sent to the main combustion chamber 44, a large amount of fuel injected through the auxiliary combustion chamber 45 is burned, and the output of the diesel engine 3 is increased. Further, by opening and closing the waste gate valve 54, the turbocharger 5
The boosting level of the intake air by 1 is adjusted.

Between the intake passage 49 and the exhaust passage 50,
Exhaust gas recirculation valve passage (EG
R passage) 56 is provided. Then, a part of the exhaust gas in the exhaust passage 50 is recirculated to the vicinity of the intake port 55 in the intake passage 49 by the EGR passage 56.
An EGR valve 57 is provided in the middle of the EGR passage 56, and the EGR valve 57 allows the exhaust gas recirculation amount (E
GR amount) is adjusted. Further, an electric vacuum regulating valve (EVRV) 58 whose opening is adjusted to open and close the EGR valve 57.
Is provided. Then, the EGRV 58 causes EGR
The EGR passage 5 is opened and closed by driving the valve 57.
E guided from the exhaust passage 50 to the intake passage 49 through 6
The amount of GR is adjusted.

A throttle valve 59 is provided in the middle of the intake passage 49, and the valve 59 is opened / closed in conjunction with the depression of the accelerator pedal 60. Also, in the intake passage 49,
A bypass passage 61 is provided alongside the throttle valve 55, and a bypass throttle valve 62 is provided in the passage 61. A two-stage diaphragm chamber actuator 63 is provided to open and close the bypass throttle valve 62. Also, two vacuum switching valves (VS for driving the actuator 63)
V) 64, 65 are provided. And each VSV6
The bypass throttle valve 62 is controlled to be opened / closed by controlling the on / off of the valves 4 and 65 and driving the actuator 63. For example, the bypass throttle valve 62 is controlled to a half open state to reduce noise and vibration during idle operation, to a fully open state to normal operation, and to a fully closed state to smoothly stop when the operation is stopped. To be done.

In the vehicle of this embodiment, the driver's seat is provided with a warning lamp 66 which is turned on to inform the driver of the deterioration abnormality of the fuel injection device including the fuel injection pump 1 and the fuel injection nozzle 4. ing. The warning lamp 66 is turned on as a result of abnormality diagnosis described later.

The electromagnetic spill valve 23, TCV3 as described above
3, glow plug 46, EVRV58, each VSV64,
65 and a warning lamp 66 are electronic control units (hereinafter simply referred to as "E
CU ") 71). And each of these members 23, 33, 46, 58, 6
The drive timing of 4, 65, 66 is controlled by the ECU 71.

As a sensor for detecting the operating state of the diesel engine 3, the following various sensors are provided in addition to the rotational speed sensor 35 described above. That is, in the vicinity of the air cleaner 67 provided at the inlet of the intake passage 49, the temperature of the air taken into the intake passage 49, that is, the intake temperature THA is detected and a signal corresponding to the magnitude of the detected value is output. An intake air temperature sensor 72 is provided. An accelerator sensor 73 is provided near the throttle valve 59 to detect the accelerator opening ACCP corresponding to the engine load from the open / close position of the valve 59 and output a signal corresponding to the detected value. There is. 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 according to the magnitude of the detected value. It is provided. Further, the diesel engine 3 is provided with a water temperature sensor 75 that detects the temperature of the cooling water, that is, the cooling water temperature THW, and outputs a signal according to the magnitude of the detected value. Further, the diesel engine 3 is provided with a crank angle sensor 76 which detects 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 outputs a signal corresponding to the rotation position. Has been. Furthermore, the transmission (not shown) is provided with a vehicle speed sensor 77 for detecting the vehicle speed (vehicle speed) SPD. This vehicle speed sensor 7
7 includes a magnet 77a rotated by the output shaft of the transmission, and the magnet 77a periodically turns on the reed switch 77b, thereby outputting a pulse signal corresponding to the vehicle speed SPD.

In this embodiment, the ECU 71 constitutes a fuel pressure change rate calculating means, a fuel volume elastic modulus calculating means, and a fuel pressure feed state value calculating means. And
The above-described sensors 72 to 77, the rotation speed sensor 35, the fuel temperature sensor 37, and the pressure sensor 47 are connected to the ECU 71, respectively. Further, the ECU 71 uses the sensors 35, 3
Based on each signal output from 7, 47, 72 to 77,
Electromagnetic spill valve 23, TCV33, glow plug 46, E
The VRV 58, each VSV 64, 65, the warning lamp 66, etc. are suitably controlled.

Next, the configuration of the above-mentioned 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, maps and the like are stored in advance, and a C
A random access memory (RAM) 83 for temporarily storing the calculation result of the PU 81, a backup RAM 84 for storing the stored data, and the like are provided. And the ECU
Reference numeral 71 is configured as a logical operation circuit in which these units 81 to 84 are connected to the input port 85, the output port 86 and the like by a bus 87.

At the input port 85, the intake air temperature sensor 72, the accelerator sensor 73, the intake air pressure sensor 74, the water temperature sensor 75, the pressure sensor 47, and the fuel temperature sensor 37 are connected to the buffers 88, 89, 90, 91, 92. , 93, a multiplexer 94, and an A / D converter 95. Similarly, the input port 85 is connected to the rotation speed sensor 35, the crank angle sensor 76, and the vehicle speed sensor 77 described above.
Are connected via the waveform shaping circuit 96. Then, the CPU 81 reads the signals from the sensors 35, 37, 47, 72 to 77, etc., which are input via the input port 85, as input values. Further, the output port 86 is connected to the respective drive circuits 97, 98, 99, 100, 101, 10
The electromagnetic spill valve 23, the TCV 33, the glow plug 46, the EVRV 58, the VSVs 64 and 65, the warning lamp 66, and the like are connected via 2, 103. And CPU81 is each sensor 35,37,47,72-7.
Based on the input value read from 7, the electromagnetic spill valve 2
3, the TCV 33, the glow plug 46, the EVRV 58, the VSVs 64 and 65, the warning lamp 66, and the like are controlled appropriately.

In this embodiment, the CPU 81 also 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 as shown in FIG.
Only one of them is shown in the block diagram of FIG.

Next, the processing contents for the fuel injection control executed by the above-mentioned ECU 71 will be described.
FIG. 6 is a “fuel pressure processing routine” which is periodically executed at predetermined time intervals among the processing executed by the ECU 71.
It is a flowchart showing.

When the processing shifts to this routine, first in step 110, the control flag F for pressure detection is detected.
Reset L to "0". Then, in step 111, the value of the fuel pressure P is sampled based on the signal from the pressure sensor 47.

Next, at step 112, it is judged if the control flag FL is "0". If the control flag FL is not "0", the process proceeds to step 120. When the control flag FL is “0”, the process proceeds to step 113.

Then, in step 113, it is judged whether or not the value of the fuel pressure P sampled this time is equal to or more than the reference value P1 immediately after the start of the fuel pressure pumping from the fuel injection pump 1. Here, when the value of the fuel pressure P is not equal to or greater than the reference value P1, the process jumps to step 111 and the processes of steps 111 to 113 are repeated. If the value of the fuel pressure P is greater than or equal to the reference value P1, step 1
Move to 14. Then, in step 114, the control flag FL is set to "1". Also, step 11
In step 5, after resetting the pointer data i to "0", the process jumps to step 111 and moves to the processing of step 111 and thereafter.

On the other hand, at step 120 after shifting from step 112, it is determined whether the control flag FL is "1". If the control flag FL is not "1", the process proceeds to step 160. Control flag F
If L is “1”, the process proceeds to step 121.

In step 121, it is judged whether or not the value of the fuel pressure P sampled this time is smaller than the reference value P2 immediately before the fuel pumped from the fuel injection pump 1 is injected from the fuel injection nozzle 4. . Here, when the value of the fuel pressure P is not smaller than the reference value P2, the process proceeds to step 130. When the value of the fuel pressure P is smaller than the reference value P2, the routine proceeds to step 122.

Then, in step 122, the pointer data i is incremented by "1". Further, in step 123, the value of the fuel pressure P sampled this time is stored in the RAM 83 as the value of the fuel pressure P (i) corresponding to the pointer data i of this time, and then the step 1
It jumps to 11 and moves to the processing of step 111 and subsequent steps.

On the other hand, in step 130 after shifting from step 121, the increment of the pointer data i is completed. That is, the current pointer data i is set to the maximum value n.

Then, in step 140, the average fuel pressure change rate AdP is calculated. That is, as shown in the flowchart of the "average fuel pressure change rate calculation routine" in FIG. 7, first in step 141, the cumulative value TdP of the fuel pressure change rate dP, which will be described later, is reset to "0". In step 142, the pointer data i is set to "1".

Subsequently, in step 143, the RAM
The fuel pressure change rate dP is calculated based on the values of the plurality of fuel pressures P (i) to P (n) stored in 83.
That is, the fuel pressure change rate dP is obtained according to the following calculation formula (1).

DP = {P (i + 1) −P (i−1)} / 2 (1) Next, in step 144, the accumulated value T up to the previous time is calculated.
A new cumulative value TdP is obtained by adding the fuel pressure change rate dP obtained this time to dP.

In step 145, the pointer data i is incremented by "1". Further, in step 146, the value of the pointer data i is the maximum value n.
Determine if it is greater than. Here, when the value of the pointer data i is not larger than the maximum value n, the fuel pressure P
Assuming that the fuel pressure change rate dP has not been obtained for all values of (i) to fuel pressure P (n), step 143
The process is jumped to and the processing of steps 143 to 146 is repeated. If the value of the pointer data i is larger than the maximum value n, it is determined that the fuel pressure change rate dP has been obtained for all the values of the fuel pressure P (i) to the fuel pressure P (n), and the routine proceeds to step 147. .

Then, in step 147, the average fuel pressure change rate AdP is calculated based on the accumulated value TdP.
That is, this average fuel pressure change rate AdP is obtained according to the following calculation formula (2).

AdP = TdP / n (2) After the calculation of the average fuel pressure change rate AdP, the process is as shown in FIG.
Then, the process proceeds to step 150.

Then, in step 150, after the control flag FL is set to "2", the process jumps to step 111 and shifts to the processing of step 111 and thereafter. on the other hand,
In step 160 after shifting from step 120, it is judged whether or not the value of the fuel pressure P sampled this time is smaller than the reference value P3 immediately after the fuel injection from the fuel injection nozzle 4. Here, the value of the fuel pressure P is the reference value P
If it is not smaller than 3, the process directly jumps to step 111 and proceeds to the processing of step 111 and thereafter. If the value of the fuel pressure P is smaller than the reference value P3, step 1
At 61, after the control flag FL is reset to "0", the process jumps to step 111 and shifts to the processing after step 111.

Here, the execution of the "fuel pressure processing routine" as described above will be described with reference to the time chart of FIG. This time chart shows the behavior of the fuel pressure P at the time of one fuel injection. As can be seen from this time chart, the average fuel pressure change rate AdP is obtained during the section from the start of the fuel pumping to the start of the fuel injection, while the fuel pressure P is between the reference value P1 and the reference value P2. The average fuel pressure change rate AdP thus obtained is obtained as an actual measurement value that reflects changes over time in the fuel system including the fuel injection pump 1 and the fuel injection nozzle 4 and the fuel properties at the time of fuel injection at that time.

Then, in this embodiment, the following control relating to fuel injection is executed using the average fuel pressure change rate AdP obtained as described above. That is, FIG.
Is a flowchart showing the processing contents of a "fuel injection control routine" executed by the ECU 71, which is periodically executed at predetermined time intervals.

When the processing shifts to this routine, first, at step 201, the various sensors 35, 37, 73 to.
Engine speed N based on various signals from 75 etc.
E, fuel temperature THF, accelerator opening ACCP, supercharging pressure P
Each value such as iM and cooling water temperature THW is read.
Further, the average fuel pressure change rate AdP obtained by the "average fuel pressure change rate calculation routine" is read.

Next, at step 202, the engine speed NE and accelerator opening ACC that have been read this time are read.
Based on the values of P, supercharging pressure PiM, cooling water temperature THW, etc.,
The target injection amount Q according to the current operating state is calculated according to a predetermined calculation formula.

In step 203, the engine speed NE, the accelerator opening ACCP, and the boost pressure Pi are also the same.
Based on the values of M, the cooling water temperature THW, etc., the target injection timing Ti corresponding to the current operating state is calculated according to a predetermined calculation formula.

Further, in step 204, based on the value of the target injection amount Q and the value of the engine rotational speed NE which are obtained this time, the engine rotational speed N is set in one fuel injection.
The period during which the fuel injection nozzle 4 should be opened, that is, the injection period Tau, is calculated according to the magnitude of E.

Next, at step 205, the fuel bulk modulus AE is calculated based on the fuel temperature THF read this time. The fuel volume elastic modulus AE is obtained by referring to a predetermined map as shown in FIG. In this map, the fuel bulk modulus AE is set to decrease as the fuel temperature THF rises.

Next, at step 206, the fuel leak rate QL as the fuel pressure feeding state value in the fuel system is calculated based on the average fuel pressure change rate AdP and the fuel volume elastic modulus AE obtained as described above. To do. Here, in general, when there is a fuel leak in the fuel system, the rate of change in fuel pressure from the start of fuel pumping to the start of fuel injection is defined by the following principle equation.

DP = AE * (QP−QL) / V (3) In this formula (3), “QP” is the oil feed rate when the fuel is pumped from the fuel injection pump 1, and is “V "Is a volume in the fuel system between the fuel injection pump 1 and the fuel injection nozzle 4, and is a design value that can be obtained in advance.

Therefore, by applying the average fuel pressure change rate AdP to the fuel pressure change rate dP from the above-mentioned principle expression (3), the fuel leak rate QL can be obtained according to the following calculation expression (4).

QL = QP-AdP * V / AE (4) Here, when the average fuel pressure change rate AdP is small or when the fuel volume elastic modulus AE is small, the fuel leakage rate Q
It can be seen that L becomes large.

In step 207, the injection timing correction value ΔTi is calculated based on the fuel leak rate QL obtained this time.
Is calculated. The injection timing correction value ΔTi is calculated according to the following calculation formula (5). "KT" in this calculation formula (5)
Is a constant obtained in advance.

ΔTi = −KT * QL (5) That is, as can be seen from the calculation formula (5), the injection timing correction value ΔTi is calculated by the following equation when the fuel leaks in the fuel system.
It is a value required to compensate the injection timing Ti by the fuel leak rate QL.

Further, in step 208, the injection period correction value ΔTau is calculated based on the target injection amount Q, the injection period Tau, the fuel leakage rate QL and the like obtained as described above.
The injection period correction value ΔTau is obtained according to the following calculation formula (6).

ΔTau = Tau * QL / {(Q / Tau) −QL} (6) That is, as can be seen from this calculation formula (6), the injection period correction value ΔTau shows the fuel leakage in the fuel system. If there is, it is a value required to compensate the injection period Tau by the fuel leakage rate QL.

Then, in step 209, the final injection timing command value TiF is calculated according to the following equation (7) based on the target injection timing Ti and the injection timing correction value ΔTi obtained as described above.

TiF = Ti + ΔTi (7) Further, in step 210, based on the injection period Tau, the injection period correction value ΔTau, and the injection timing command value TiF obtained as described above, the following formula (8) is used. ,
A final spill timing command value Tsp corresponding to the fuel injection end timing is calculated.

Tsp = TiF + Tau + ΔTau (8) Then, in step 211, the injection timing control is executed based on the injection timing command value TiF obtained this time.
That is, by controlling the TCV 33 based on the injection timing command value TiF and controlling the timer device 26, the timing of the pressure feed of the fuel from the fuel injection pump 1 to the fuel injection nozzle 4 is adjusted, and thus the fuel from the fuel injection nozzle 4 is adjusted. It controls the injection timing.

Further, at step 212, the fuel injection amount control is executed based on the spill timing command value Tsp obtained this time, and the subsequent processing is temporarily terminated. That is, by controlling the electromagnetic spill valve 23 on the basis of the spill timing command value Tsp, the pressure feed of fuel from the fuel injection pump 1 to the fuel injection nozzle 4 is controlled, and thus the fuel injection amount from the fuel injection nozzle 4 is controlled. . The fuel injection control is executed as described above.

On the other hand, in this embodiment, the following fuel system abnormality diagnosis processing is executed by using the fuel leakage rate QL obtained as described above. That is, FIG. 11 shows the ECU 7
3 is a flowchart showing the processing contents of a "fuel system diagnosis routine" executed by No. 1, which is periodically executed at predetermined time intervals.

When the processing shifts to this routine, first, at step 310, the value of the fuel leakage rate QL obtained in the "fuel injection control routine" is read. Subsequently, in step 320, it is determined whether or not the value of the fuel leakage rate QL read this time is larger than a predetermined reference value α. Here, when the value of the fuel leakage rate QL is not larger than the reference value α, it is determined that the change over time in the fuel system and the change in fuel property are not larger than necessary, and the subsequent processing is temporarily terminated. On the other hand, fuel leakage rate QL
If the value of is larger than the reference value α, it is determined that there is an excessive change in the fuel system with time or the change in the fuel property, and the fuel system is abnormal, and the process proceeds to step 330.

Then, in step 330, the warning lamp 66 is turned on to inform the driver of the abnormality of the fuel system. Further, in step 340, the backup system 84 stores a fuel system abnormality diagnostic code for indicating that the fuel system has an abnormality, and the subsequent processing is temporarily terminated. In this way, the abnormality diagnosis of the fuel system is executed.

As described above, according to the fuel injection control of this embodiment, the change with time in the fuel system from the fuel injection pump 1 to the fuel injection nozzle 4 and the fuel injection nozzle 4 are executed every time a single fuel injection is executed. The fuel leakage rate QL that reflects changes in the fuel properties and the like is obtained as an actual measurement value. Also, the fuel leak rate QL
The spill timing command value Tsp and the injection timing command value TiF corrected based on the above are obtained. Then, based on the spill timing command value Tsp and the injection timing command value TiF,
The fuel injection pump 1 is drive-controlled to execute fuel injection amount control and fuel injection timing control.

Therefore, in each fuel injection, the amount of fuel pressure-fed from the fuel injection pump 1 to the fuel injection nozzle 4 depends on the fuel pressure-feeding state due to the change with time in the fuel system and the change in fuel properties such as fuel viscosity. That is, the change in the fuel leak rate QL is corrected and the influence of the fuel leak rate QL is eliminated. For this reason, the desired fuel amount can be pumped to the fuel injection nozzle 4 and injected without being affected by changes over time in the fuel system and changes in fuel properties. Similarly, fuel can be injected from the fuel injection nozzle 4 at the desired injection start timing.

As a result, the fuel injection amount control and the fuel injection timing control with high accuracy can always be stably performed by coping with the change with time and the change in the fuel property in the fuel system. For example, even if abrasion occurs between the cam plate 8 and the cam roller 10 in the fuel injection pump 1 and the absolute stroke amount of the plunger 12 changes or the fuel viscosity changes, the changes are dealt with in response to those changes. Injection control can be performed with high accuracy. Further, as a result, smoke and emission of nitrogen oxides (NOx) from the diesel engine 3 can be suppressed. Moreover, in this embodiment, in the fuel system from the fuel injection pump 1 to the fuel injection nozzle 4, the fuel pressure P in the pressure increasing process immediately before the fuel injection nozzle 4 reaches the valve opening, that is, immediately before the start of fuel injection is detected. Then, the average fuel pressure change rate AdP is obtained based on the value of the fuel pressure P. Further, the fuel bulk modulus AE is obtained based on the fuel temperature THF at that time. Then, based on the average fuel pressure change rate AdP and the fuel volume elastic modulus AE, the fuel leakage rate QL that reflects the fuel pressure feeding state in the fuel system is obtained.

Therefore, at each fuel injection, the proper fuel leakage rate QL is measured from the fuel pressure P and the fuel temperature THF actually detected in the fuel system, which reflects the temporal change and the fuel property change. It can be obtained as a value. That is, it is possible to always grasp the fuel pressure feeding state with high accuracy. Moreover, various conditions of the entire fuel system can be reflected in the average fuel pressure change rate AdP.

As a result, the environmental condition in the fuel system is grasped more accurately from the average fuel pressure change rate Adp, and accordingly the more precise injection timing correction value ΔTi and injection period correction value Δ are obtained.
Tau can be calculated. Also, each of these correction values Δ
A more accurate injection timing command value T based on Ti and ΔTau
The iF and the spill timing command value Tsp can be obtained. In that sense, the fuel injection amount control and the fuel injection timing control can be performed with higher accuracy.

In addition, in this embodiment, the fuel leakage rate QL
When the fuel system is diagnosed to be abnormal based on the above, the warning lamp 66 is turned on, so that the driver can be notified in real time of the abnormality of the fuel system. or,
Since the diagnostic code relating to the abnormality of the fuel system is stored in the backup RAM 84, it is possible to confirm the presence or absence of the abnormality of the fuel system by reading the data of the backup RAM 84 at the time of periodical inspection of the engine. .

The present invention is not limited to the above-described embodiment, but may be implemented as follows with a part of the configuration appropriately changed without departing from the spirit of the invention. (1) In the above embodiment, the fuel leak rate QL that reflects the fuel pumping state is obtained based on the average fuel pressure change rate AdP obtained from the fuel pressure P and the fuel bulk modulus AE obtained from the fuel temperature THF. The injection timing command value TiF and the spill timing command value Tsp are corrected based on the fuel leak rate QL. On the other hand, based on the average fuel pressure change rate AdP and the fuel bulk modulus AE, the fuel leakage rate Q
Instead of L, the oil feed rate that reflects the fuel pressure feeding state may be obtained, and the injection timing command value TiF and the spill timing command value Tsp may be corrected based on the oil feed rate.

(2) In the above embodiment, the fuel leak rate QL is obtained based on the average fuel pressure change rate AdP and the fuel volume elastic modulus AE, and the injection timing correction value ΔTi and the injection period are calculated based on the fuel leak rate QL. The correction value ΔTau was obtained. On the other hand, in order to prevent the influence of noise and errors in the correction values ΔTi and ΔTau, the correction values ΔTi and ΔTau may be obtained from the weighted average of a plurality of past calculation data.

(3) In the above embodiment, the average fuel pressure change rate AdP is obtained by averaging the accumulated values TdP of the plurality of fuel pressure change rates dP obtained from the start of fuel pumping to the start of injection. It was On the other hand, the fuel pressure change rate dP at a certain pressure point from the start of fuel pumping to the start of injection is calculated each time, and the average value is obtained by averaging the values of the fuel pressure change rate dP at a plurality of past times at that pressure point. The fuel pressure change rate AdP may be obtained. Alternatively, the average fuel pressure change rate AdP may be determined by learning control.

(4) In the above embodiment, the injection timing command value TiF and the spill timing command value Tsp are corrected based on the fuel leak rate QL obtained based on the average fuel pressure change rate AdP and the fuel volume elastic modulus AE. I did it. On the other hand, based on the fuel leakage rate QL obtained based on the average fuel pressure change rate AdP and the fuel bulk modulus AE, the EGR
You may make it correct | amend various parameters, such as.

(5) In the above-described embodiment, the fuel leak rate QL required in each operation region of the diesel engine 3 is calculated.
The injection timing command value TiF and the spill timing command value Tsp are corrected or the fuel system abnormality is diagnosed based on the above. On the other hand, the injection timing command value TiF and the spill timing command value Tsp in the entire operating range are corrected and the fuel system abnormality is diagnosed based on the fuel leak rate QL that is obtained only when the diesel engine 3 is running at low speed. You may. In this case, the fuel leakage rate QL increases as the diesel engine 3 rotates at a low speed, and can be obtained as an accurate value. As a result, the injection timing command value TiF and the spill timing command value Tsp can be corrected and the fuel system abnormality can be diagnosed more accurately.

(6) In the above embodiment, the pressure sensor 47 for detecting the fuel pressure P is provided in the fuel injection nozzle 4, but the pressure sensor is provided corresponding to the high pressure chamber of the fuel injection pump, or each fuel injection is performed. You may provide in the middle of the fuel pipe line leading to a nozzle.

(7) In the above embodiment, the diesel engine 3 is embodied as an internal combustion engine, but it is limited to a diesel engine as long as it is an internal combustion engine having a fuel injection device having a fuel injection pump and a fuel injection nozzle. Not a thing.

[0089]

As described above in detail, according to the present invention, based on the fuel pressure detected in the fuel system from the fuel injection pump to the fuel injection nozzle, from the start of fuel pressure feed to the start of fuel injection. Calculate the fuel pressure change rate. Also, the fuel bulk modulus is obtained based on the fuel state. Then, the fuel pressure feeding state value is obtained based on the fuel pressure change rate and the fuel volume elastic modulus. Therefore, an appropriate fuel pressure-feeding state value that reflects changes over time in the fuel system and changes in fuel properties is always required. As a result, it is possible to always grasp an appropriate fuel pumping state, and to exhibit an excellent effect that the fuel injection can be optimized by coping with the change with time and the change in the fuel property in the fuel system. .

[Brief description of 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 diesel engine system with a supercharger in an embodiment embodying the present invention.

FIG. 3 is a cross-sectional view showing a distributed fuel injection pump in one embodiment.

FIG. 4 is a side view showing a fuel injection nozzle in one embodiment.

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

FIG. 6 is a flowchart showing a “fuel pressure processing routine” executed by the ECU in the embodiment.

FIG. 7 is a flowchart showing an “average fuel pressure change rate calculation routine” executed by an ECU in one embodiment.

FIG. 8 is a time chart showing a behavior of fuel pressure during one fuel injection and a calculation section of an average fuel pressure change rate at that time in one embodiment.

FIG. 9 is a flowchart showing a “fuel injection control routine” executed by the ECU in the embodiment.

FIG. 10 is a map showing the relationship between the fuel bulk modulus and the fuel temperature in one example.

FIG. 11 is a flowchart showing a “fuel system diagnosis routine” executed by the ECU in one embodiment.

[Explanation of symbols]

1 ... Fuel injection pump, 3 ... Diesel engine as internal combustion engine, 4 ... Fuel injection nozzle, 37 ... Fuel temperature sensor (3
7 constitutes fuel state detection means), 47 ... Pressure sensor (47 constitutes fuel pressure detection means), 71 ...
The ECU (71 constitutes a fuel pressure change rate calculation means, a fuel volume elastic modulus calculation means, and a fuel pressure feed state value calculation means.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical indication location F02M 63/00 U 65/00 304 (72) Inventor Takehiko Hirose 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Automobile Co., Ltd. (72) Inventor, Akira Shibata, 1-1, Showa-cho, Kariya city, Aichi Prefecture, Nihon Denso Co., Ltd. (72) Inventor, Teiji Inuma, 1-1, Showa-cho, Kariya city, Aichi Prefecture, Nippon Denso Co., Ltd. In-house (72) Inventor Kenzo Yano 1-1, Showa-cho, Kariya City, Aichi Prefecture, Nihon Denso Co., Ltd. (72) Inventor, Tatsuya Ichikawa 1-1-1-1, Showa-cho, Kariya City, Aichi Prefecture, Nihon Denso Co., Ltd.

Claims (1)

[Claims] 1. A fuel injection nozzle for injecting fuel into an internal combustion engine by opening the valve by fuel pressure, a fuel injection pump for pumping fuel to the fuel injection nozzle, and a fuel injection from the fuel injection pump. Fuel pressure detection means for detecting the fuel pressure in the fuel system up to the nozzle, and the fuel pressure detection means between the start of pressure feed and the start of injection of the fuel pressure-fed from the fuel injection pump to the fuel injection nozzle. Based on the detection result of, the fuel pressure change rate calculation means for calculating the change rate of the fuel pressure, the fuel state detection means for detecting the state of the fuel, based on the detection result of the fuel state detection means, A fuel volume elastic modulus calculating means for calculating the bulk elastic modulus of the fuel; a calculation result of the fuel pressure change rate calculating means and a calculation result of the fuel volume elastic modulus calculating means. A fuel injection device for an internal combustion engine, comprising: a fuel pressure-feeding state value calculation means for calculating a pressure-feeding state value of fuel that is pressure-fed from the fuel injection pump to the fuel injection nozzle.