JP3027893B2 - Environment determination system in fuel system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel system environment judging device for judging an environmental condition in a fuel system from a fuel injection pump to a fuel injection nozzle.

[0002]

2. Description of the Related Art Conventionally, in a fuel injection device for an internal combustion engine provided with a fuel injection pump and a fuel injection nozzle, various methods have been employed in order to match the fuel injection amount and the fuel injection timing from the fuel injection nozzle to the target values. Is performed.

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 operation 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. Thus, the end of the pressure feeding of the fuel from the fuel injection pump to the fuel injection nozzle, that is, the end timing (fuel injection amount) of the fuel injection from the fuel injection nozzle to each cylinder is controlled. Alternatively, a timer device provided in the fuel injection pump is drive-controlled so that the fuel injection timing becomes a target injection timing determined according to the operation state of the engine. By this control, the reciprocating timing of the plunger is adjusted, and the timing of fuel pumping from the fuel injection pump to the fuel injection nozzle, that is, the fuel injection start timing (fuel injection timing) at the fuel injection nozzle is retarded or advanced. Controlled to the side.

[0004] However, even in the electronically controlled diesel engine as described above, the fuel system from the fuel injection pump to the fuel injection nozzle sometimes changes over time and the difference in fuel properties, that is, in the fuel system. There are differences in environmental conditions. Therefore, these changes over time and differences in fuel properties,
In other words, unless the environmental condition in the fuel system is reflected, the control of the fuel injection amount and the control of the injection timing deviate from the desired target values. As a result, there is a possibility that the amount of smoke and the emission of nitrogen oxides (NOx) from the engine may increase.

In view of the above-mentioned problems, Japanese Patent Application Laid-Open No. 56-75928 discloses a technique for improving the accuracy of fuel injection amount control by coping with the aging of the fuel system. I have. In this conventional technique, feedback control of the engine speed is performed when the engine is idling. Further, at that time, the amount of displacement of the position of the control sleeve driven by the fuel injection pump with respect to the reference position is obtained as a temporal change of the fuel system. Then, the fuel injection amount is corrected based on the displacement amount.

On the other hand, Japanese Patent Laid-Open No. 185839/1984 discloses a technique for improving the accuracy of the fuel injection amount control particularly in response to the difference in the fuel properties in the fuel system. In this conventional technique, as the fuel property, there is a problem that the fuel viscosity changes due to the fuel composition and the fuel temperature. Then, the fuel injection timing control, which is usually performed by the feedback control, is temporarily stopped when the engine is idling. A signal for fixing the injection timing control actuator is provided. At this time, the deviation between the actually detected fuel injection timing and the reference injection timing is obtained as a value that correlates with the change in fuel viscosity. Then, the fuel injection amount is corrected based on the deviation.

[0007]

However, in each of the above-mentioned prior arts, only the change with time and the correlation value of the fuel viscosity are obtained only during idling, and it is not always possible to always obtain the correlation value of the change with time and the fuel viscosity. could not. In particular, since the fuel viscosity changes with the lapse of time after the engine is started, it is desirable that the fuel viscosity be determined in accordance with the change. Further, since the correlation value of the change with time and the correlation value of the fuel property mutually affect each other, it is not efficient to obtain them separately with different parameters.
Rather, it can be said that it is desirable to obtain complex and efficient correlation values of various conditions in the fuel system, including time-dependent changes, fuel properties, and the like, and reflect them in fuel injection control as necessary.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and has as its object to reduce the amount of change affecting the fuel injection control, such as aging of the fuel system and fuel properties, in various conditions within the fuel system. It is an object of the present invention to provide an in-fuel-system environment determining apparatus capable of constantly and efficiently determining a single correlation as a composite correlation value of the above.

[0009]

In order to achieve the above object, according to the present invention, as shown in FIG. 1, a fuel injection nozzle M1 which is opened by fuel pressure, and a fuel injection nozzle M1 is provided to the fuel injection nozzle M1. Injection pump M for pumping oil
2 and the fuel injection nozzle M1 from the fuel injection pump M2.
Pressure detection means M3 for detecting the fuel pressure in the fuel system up to and a predetermined clamp immediately before fuel injection of the fuel pressure based on the detection result of the fuel pressure detection means M3.
Fuel pressure change rate calculating means M4 for calculating the change rate within the angle range, and the fuel pressure change rate calculating means M
The gist is that an in-fuel-system environment determining means M5 for determining an environmental state in the fuel system based on the calculation result of No. 4 is provided.

[0010]

Therefore, according to the above configuration, each time fuel is injected from the fuel injection nozzle M1, the fuel pressure is detected based on the fuel pressure actually detected by the fuel pressure detecting means M3 in the fuel system.
Then, the fuel pressure change rate in a predetermined crank angle range immediately before fuel injection is determined. Then, from the fuel pressure change rate, an environmental state in the fuel system that reflects a temporal change of the fuel system, a fuel property, and the like is determined. Further, since the fuel pressure change rate changes by reflecting the aging of the fuel system, the fuel properties, etc., the environmental state in the fuel system is determined from this value in a complex manner.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the apparatus for determining the environment in a fuel system 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 pressurizing fuel 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 36 composed of a constant pressure valve (CPV) is provided at the outlet side of each distribution passage 18. The delivery valve 36 is connected to the distribution passage 1
This is for preventing the backflow of the fuel pumped from 8 to the fuel line 4a.

The pump housing 13 of this embodiment is provided with a pressure sensor 37 constituting a fuel pressure detecting means corresponding to the high-pressure chamber 15. This pressure sensor 37
Detects the pressure in the high-pressure chamber 15 as the fuel pressure P in the fuel system from the fuel injection pump 1 to the fuel injection nozzle 4, and outputs a signal corresponding to the magnitude of the detected value.

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. Then, the position of the timer piston 28 (hereinafter referred to as “timer position”) TP is determined based on the balance between the fuel pressure and the urging force of the timer spring 31. Further, by determining the timer position TP, 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. By adjusting the fuel pressure, the reciprocating timing of the plunger 12 is controlled, and the fuel injection timing of the fuel injection nozzle 4 is controlled to be advanced or retarded.

In this embodiment, a well-known timer position sensor 38 is provided on the low pressure chamber 29 side of the timer housing 27 to detect the actual fuel injection timing controlled by the timer device 26. . The timer position sensor 38 operates in conjunction with the timer piston 28, detects a timer position TP corresponding to the fuel injection timing, and outputs a signal corresponding to the magnitude of the detected value.

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.

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 55, 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. In this embodiment, the ECU 71 constitutes a fuel pressure change rate calculating means and a fuel system environment determining means.

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. The crank angle sensor 7 detects a rotation reference position of the crankshaft 40, for example, a rotation reference position Gn of the crankshaft 40 with respect to the top dead center of a specific cylinder, and outputs a signal corresponding to the rotation reference position Gn.
6 are 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 is a magnet 7 rotated by an output shaft of the transmission.
A pulse signal corresponding to the vehicle speed SPD is output when the reed switch 77b is periodically turned on by the magnet 77a.

The ECU 71 is connected to the above-described sensors 72 to 77, the rotation speed sensor 35, the pressure sensor 37, and the timer position sensor 38. E
Based on various signals output from the sensors 35, 37, 38, 72 to 77, the CU 71 determines whether the electromagnetic spill valve 23, TC
V33, glow plug 46, EVRV58 and each VSV
64, 65, etc. 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 includes the above-described intake air temperature sensor 72, accelerator sensor 73, intake air pressure sensor 74, water temperature sensor 75, pressure sensor 37, and timer position sensor 38.
Are the buffers 88, 89, 90, 91, 92, 93,
They are connected via a multiplexer 94 and an A / D 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 reads, as input values, signals from the sensors 35, 37, 38, 72 to 77, etc., which are input via the input port 85. The output ports 86 are connected to the respective drive circuits 97, 98, 99, 100, 101, 10
2, the electromagnetic spill valve 23, the TCV 33, the glow plug 46, the EVRV 58, and the respective VSVs 64, 65 are connected. Then, the CPU 81 controls the sensors 35, 3
Based on the input values read from 7, 38, 72-77,
Electromagnetic spill valve 23, TCV 33, glow plug 46, E
The VRV 58 and the VSVs 64, 65, etc., are suitably controlled.

In this embodiment, the CPU 81 has a timer function. Also, in this embodiment,
Although the glow plug 46 is provided for each cylinder of the diesel engine 3, only one of them is shown in the block diagram of FIG. 4 for convenience.

Next, the contents of processing for fuel injection control executed by the ECU 71 will be described with reference to FIGS. FIG. 5 is a diagram showing a “environment constant in the fuel system” for calculating an environmental constant ρ in the fuel system that reflects an environmental state in the fuel system from the fuel injection pump 1 to the fuel injection nozzle 4 among the processes executed by the ECU 71. 6 is a flowchart showing the processing contents of an "arithmetic routine", which is periodically executed at predetermined time intervals.

When the process proceeds to this routine, first, at step 110, the engine speed NE, the timer position TP, and the rotation reference position Gn are determined based on signals from the rotation speed sensor 35, the timer position sensor 38, the crank angle sensor 76, and the like. And so on.

Subsequently, in step 120, it is determined whether or not the plunger 12 is in the compression stroke immediately before the start of injection. That is, it is determined whether or not the fuel injection nozzle 4 is immediately before the valve is opened. This determination is based on the currently read engine speed NE, timer position TP, and rotation reference position G.
This is performed based on n or the like. Then, when the plunger 12 is not in the compression stroke immediately before the start of the injection, the subsequent processing is once ended as it is. On the other hand, when the plunger 12 is in the compression stroke immediately before the start of the injection, the process proceeds to step 130.

In step 130, the pressure sensor 3
7, the fuel pressure Pi at that time ti is read. Further, in step 140, based on the fuel pressure Pi read this time, the one time differential value (dPi / dti) of the fuel pressure Pi is calculated as the fuel pressure P
The calculation is performed as the change rate of i (fuel pressure change rate). In this embodiment, a plurality of one-time differential values (dPi / dt) are obtained in a predetermined crank angle range in a compression stroke immediately before the start of injection.
i) is calculated. These first derivative values (dPi / dt
i) reflects changes over time, fuel properties, and the like in the fuel system from the fuel injection pump 1 to the fuel injection nozzle 4.

Next, in step 150, based on a plurality of one-time differential values (dPi / dti) calculated this time,
The average fuel pressure change rate ΔPA is calculated. That is, an average fuel pressure change rate in a predetermined crank angle range immediately before the start of injection is obtained.

Subsequently, in step 160, a change in the volume volume V in the fuel system that changes per unit time with the lift of the plunger 12, that is, a change in volume volume ΔV is calculated. This volume volume change Δ
V is obtained according to the engine speed NE and the like. or,
In step 170, the volume volume V0 before the change by the volume volume change amount ΔV, that is, one volume unit time before, is calculated. This volume volume V0 is obtained according to the engine speed NE and the like.

Subsequently, in step 180, based on the average fuel pressure change rate ΔPA, the volume volume change ΔV, and the volume volume V0 obtained as described above,
The current environmental constant ρ in the fuel system is calculated. The calculation of the environmental constant ρ in the fuel system is performed according to the following formula.

Ρ = ΔPA * (V 0 + ΔV) / V 0 In step 190, the environmental constant ρ in the fuel system obtained this time is temporarily stored in the RAM 83, and the subsequent processing is temporarily ended.

Here, the calculation of the environmental constant ρ in the fuel system will be described with reference to a time chart shown in FIG. This time chart shows the behavior of the fuel pressure P and its one-time derivative (dP / dt) during one fuel injection.

When the plunger 12 of the fuel injection pump 1 starts to lift at time t1 when one fuel injection is executed, as shown in FIG.
Begins to rise and gradually increases. At this time, the one-time differential value (dP / dt) of the fuel pressure P changes as shown in FIG. The ECU 71 determines that the process of increasing the fuel pressure P is a compression stroke immediately before the start of injection. And an inflection point A at which the fuel pressure P in the increasing process greatly changes.
Is the injection start time ts when the fuel injection nozzle 4 reaches the valve opening. Further, the fuel pressure P at the time t2 becomes the injection start pressure Ps. In the ECU 71, the average slope of the rise of the fuel pressure P immediately before the injection start time ts, that is, the magnitude of the one-time differential value (dP / dt) between the time t1 and the time t2 is determined by the average fuel pressure. It is obtained as the rate of change ΔPA. In the ECU 71,
The environmental constant p in the fuel system is obtained based on the average fuel pressure change rate ΔPA. Here, in the fuel system from the fuel injection pump 1 to the fuel injection nozzle 4, the average fuel pressure change rate Δ
When PA is large, the environmental constant ρ in the fuel system increases. On the other hand, when the average fuel pressure change rate ΔPA is small, the environmental constant ρ in the fuel system becomes small. Further, the average fuel pressure change rate ΔPA is obtained as an actual measurement value reflecting the fuel property and the change over time of the fuel system at that time, and the environmental constant ρ in the fuel system reflects the fuel property and the change over time of the fuel system. It is obtained as the actual measured value.

In this embodiment, the following fuel injection amount control is executed using the in-fuel environmental constant ρ obtained as described above. That is, FIG.
Is a flowchart showing the processing content of a "fuel injection amount control routine" executed by the control unit, and is periodically executed at predetermined intervals.

When the processing shifts to this routine, first, at step 210, based on various signals from the rotation speed sensor 35, the accelerator sensor 73, the intake pressure sensor 74, the water temperature sensor 75 and the like, the engine rotation speed NE and the supercharging pressure P
iM, cooling water temperature THW, accelerator opening ACCP, etc. are read.

Subsequently, at step 220, a basic injection quantity Qb corresponding to the current operating state is calculated based on the engine speed NE and the accelerator opening ACCP. or,
In step 230, the basic injection amount Qb obtained this time based on the current cooling water temperature THW, the supercharging pressure PiM, etc.
To calculate the corrected injection amount Q1. That is, the corrected injection amount Q1 is obtained in a cold state or in accordance with the operation state of the turbocharger 51.

Thereafter, at step 240, the RAM
The latest environmental constant ρ in the fuel system stored in 83 is read. In step 250, an injection amount correction value α is calculated based on the fuel system environmental constant ρ read this time. The calculation of the injection amount correction value α is performed by the environmental constant ρ in the fuel system.
And the injection amount correction value α are determined with reference to a map (not shown) in which the relationship is determined in advance. Here, when the environmental constant ρ in the fuel system is small, it is considered that fuel leakage from the fuel system is large, so that it is determined that the change in the environmental state in the fuel system is large, and the injection amount correction value α Is obtained as a correction value for increasing the fuel injection amount.

Subsequently, in step 260, a final target injection amount Q is calculated based on the corrected injection amount Q1 and the injection amount correction value α obtained this time. Here, when the injection amount correction value α is a value corresponding to the correction amount of the injection amount, the target injection amount Q is obtained by adding or subtracting the injection amount correction value α to the corrected injection amount Q1. Can be Alternatively, when the injection amount correction value α is a value corresponding to the correction coefficient of the injection amount, the target injection amount Q is obtained by multiplying the injection amount correction value α by the corrected injection amount Q1. It is obtained by adding or subtracting from Q1.

Then, in step 270, fuel injection is executed based on the target injection amount Q obtained this time, and the subsequent processing is temporarily terminated. That is, by controlling the electromagnetic spill valve 23 based on the target injection amount Q, the pressure of fuel 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. is there.

In addition, in this embodiment, the following fuel injection timing control is executed using the environmental constant ρ in the fuel system. That is, FIG. 8 is a flowchart showing the processing of the “fuel injection timing control routine” executed by the ECU 71, which is periodically executed at predetermined intervals.

When the process proceeds to this routine, first, at step 310, the engine speed NE is determined based on various signals from the rotation speed sensor 35, the timer position sensor 38, the accelerator sensor 73, the intake pressure sensor 74, the water temperature sensor 75, and the like. , The timer position TP, the supercharging pressure PiM, the cooling water temperature THW, the accelerator opening ACCP, and the like, respectively.

Subsequently, at step 320, the currently read engine rotational speed NE and accelerator opening AC
Based on the CP, a basic injection start timing Tb according to the current operation state is calculated. In step 330, the corrected injection start timing T1 is calculated by correcting the basic injection start timing Tb based on the cooling water temperature THW, the supercharging pressure PiM, and the like read this time. That is, the corrected injection start timing T1 is determined according to the cold state or the operating state of the turbocharger 51.

Thereafter, in step 340, the RAM
The latest environmental constant ρ in the fuel system stored in 83 is read. In step 350, an injection start timing correction value β is calculated based on the fuel system environmental constant ρ read this time. The calculation of the injection start timing correction value β is performed with reference to a map (not shown) in which the relationship between the fuel system environment constant ρ and the injection start timing correction value β is determined in advance. Here, when the environmental constant ρ in the fuel system is small, it is considered that the fuel leakage from the fuel system is large, so that it is determined that the change in the environmental state in the fuel system is large, and the injection start timing correction value β is obtained as a correction value in a direction to advance the injection start timing.

Subsequently, in step 360, a final target injection start timing T is calculated based on the corrected injection start timing T1 and the injection start timing correction value β obtained this time. Here, when the injection start timing correction value β is a value corresponding to the correction timing of the injection start timing, the target injection start timing T adds the injection start timing correction value β to the corrected injection start timing T1 or It is determined by subtraction. Alternatively, if the injection start timing correction value β is a value corresponding to a correction coefficient of the injection start timing, the target injection start timing T is a result of multiplication of the injection start timing correction value β and the corrected injection start timing T1. Is added to or subtracted from the corrected injection start timing T1.

Then, in step 370, fuel injection is executed based on the target injection start timing T obtained this time, and the subsequent processing is temporarily terminated. That is, by controlling the TCV 33 based on the target injection start timing T and controlling the timer device 26, the timing of pumping the fuel from the fuel injection pump 1 to the fuel injection nozzle 4 is adjusted, and the fuel from the fuel injection nozzle 4 is thereby adjusted. It controls the injection timing.

As described above, according to the fuel injection control of this embodiment, every time one fuel injection is executed, the environmental condition in the fuel system from the fuel injection pump 1 to the fuel injection nozzle 4 That is, the environmental constant ρ in the fuel system, which reflects the fuel properties and the aging of the fuel system, is obtained as an actually measured value.
Further, the target injection amount Q and the target injection start timing T corrected based on the environmental constant ρ in the fuel system are obtained. Then, based on the target injection amount Q and the target injection start timing T, the driving of the fuel injection pump 1 is controlled, and the fuel injection amount control and the fuel injection timing control are executed.

Therefore, in each fuel injection, the amount of fuel pumped from the fuel injection pump 1 to the fuel injection nozzle 4 is corrected for a change due to the environmental condition in the fuel system, and the change in the fuel amount is corrected. The effect is eliminated. Therefore, even if the environmental condition in the fuel system changes for some reason,
The desired fuel amount can be pumped to the diesel engine 3 and injected without being affected by the change. Similarly, fuel can be injected into the diesel engine 3 at a desired injection start timing.

As a result, highly accurate fuel injection amount control and fuel injection timing control can always be stably performed in response to changes in the environmental conditions in the fuel system. For example, if the line constants (line resistance, coefficient of thermal expansion, elastic modulus, etc.) of the fuel system change, if there is a fuel leak in the fuel system, or if the fuel temperature changes, take measures against it. Fuel injection control can be performed with high accuracy. As a result, the emission of smoke and nitrogen oxides (NOx) from the diesel engine 3 can be suppressed.

Further, in this embodiment, in the fuel system from the fuel injection pump 1 to the fuel injection nozzle 4, the fuel pressure in the pressure increasing process immediately before the fuel injection nozzle 4 is opened, that is, immediately before the start of fuel injection. P is detected. Then, the average fuel pressure change rate ΔPA is obtained based on the fuel pressure P as one of the parameters, and the environmental constant ρ in the fuel system is obtained based on the average fuel pressure change rate ΔPA.

Accordingly, at each fuel injection, the fuel system environment constant ρ reflecting the current fuel properties and the fuel system's aging is used as the measured value from the fuel pressure P actually detected in the fuel system. Obtainable. That is, it is possible to obtain the environmental constant ρ in the fuel system that accurately reflects the changes in the various conditions in response to the difference in the pipeline constant of the fuel system, the fuel leakage in the fuel system, and the change in the fuel temperature. it can.

Moreover, the environmental constant ρ in the fuel system reflects various conditions of the entire fuel system, unlike the fuel elasticity and the like which are indirectly converted from the fuel temperature detected at a specific point in the fuel system. be able to. That is, when viewed from the whole fuel system, a predetermined temperature distribution exists in the fuel temperature, and it is inevitable that the fuel temperature required at a specific point is biased. Therefore, a value that reflects various conditions of the entire fuel system cannot be accurately obtained from the uneven fuel temperature. On the other hand, the fuel pressure P reflects various conditions such as temperature conditions of the entire fuel system, fuel leakage, and variations in rigidity of the fuel system, that is, environmental conditions in a complex manner.

That is, fuel system changes over time, fuel properties, etc.
The environmental constant ρ in the fuel system which has an effect on the control of fuel injection
Can be obtained as a composite correlation value of various conditions in the fuel system. In addition, the environmental constant ρ in the fuel system can always and efficiently be obtained with a single parameter of the fuel pressure P.

As a result, the environmental condition in the fuel system is more accurately determined from the environmental constant ρ in the fuel system reflecting changes in various conditions of the entire fuel system, and a more accurate injection amount correction value α and The injection start timing correction value β can be obtained.
Further, based on these correction values α and β, more accurate target injection amount Q and target injection start timing T can be obtained. In this sense, the fuel injection amount control and the fuel injection timing control can be performed with higher accuracy.

It should be noted that the present invention is not limited to the above-described embodiment, and 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 above embodiment, the first derivative of the fuel pressure P (dP
i / dti) to determine an injection amount correction value α and an injection start timing correction value β based on the in-fuel environmental constant ρ obtained from
The target injection amount Q and the target injection start timing T are corrected based on the correction values α and β. On the other hand, the amount of fuel remaining in the fuel system after the end of fuel injection is determined each time based on the in-fuel environmental constant ρ obtained from the one-time differential value (dPi / dti) of the fuel pressure P and the injection start pressure Ps. May be obtained, and the fuel injection amount or the fuel injection start timing may be corrected based on the remaining fuel amount change.

(2) In the above embodiment, the injection amount correction value α and the injection start timing correction value β were obtained based on the environmental constant ρ in the fuel system obtained from the one-time differential value (dPi / dti) of the fuel pressure P. However, in order to prevent the influence of noise or error in each of the correction values α and β, the correction values α and β can be obtained from a weighted average of a plurality of past calculation data. (3) In the above-described embodiment, a plurality of one-time differential values (dPi / dti) of the fuel pressure Pi in a predetermined crank angle range immediately before the start of the injection are calculated by the “environment constant calculation routine in the fuel system”. The average fuel pressure change rate ΔPA was determined from the average value of the differential times (dPi / dti). On the other hand, a one-time differential value (dPi / dti) of the fuel pressure P at a certain pressure point immediately before the start of injection is calculated each time, and a plurality of past sampling data of the fuel pressure P at the pressure point are averaged to obtain an average value. The fuel pressure change rate ΔPA may be obtained. Alternatively, the average fuel pressure change rate ΔPA may be determined by learning control.

(4) In the above embodiment, the fuel injection amount control and the fuel injection timing control are performed based on the environmental constant ρ in the fuel system obtained from the one-time differential value (dPi / dti) of the fuel pressure P. . On the other hand, based on the environmental constant ρ in the fuel system obtained from the one-time differential value (dPi / dti) of the fuel pressure P, the malfunction of the fuel system is determined, and the driver is notified of the malfunction or the malfunction is notified. May be executed in a fail-safe mode to cope with the situation. For example,
If the environmental constant ρ in the fuel system is extremely low, it is possible that the type of the fuel itself is different or the amount of fuel leakage in the fuel system is too large. You may.

(5) In the above embodiment, the fuel injection amount control and the fuel injection timing control are performed based on the environmental constant ρ in the fuel system obtained from the one-time differential value (dPi / dti) of the fuel pressure P. . On the other hand, various parameters such as the fuel injection rate and EGR may be corrected based on the environmental constant ρ in the fuel system obtained from the one-time differential value (dPi / dti) of the fuel pressure P.

(6) In the above embodiment, the pressure sensor 37 for detecting the fuel pressure P is provided corresponding to the high-pressure chamber 15 of the fuel injection pump 1. However, the pressure sensor is provided for each fuel injection nozzle of each cylinder of the diesel engine. May be provided.

(7) In the above embodiment, the diesel engine 3 is used as an internal combustion engine. However, any internal combustion engine having a fuel injection device having a fuel injection pump and a fuel injection nozzle is limited to the diesel engine. Not something.

[0075]

As described above in detail, according to the present invention, the predetermined pressure immediately before the fuel injection is determined based on the fuel pressure detected in the fuel system from the fuel injection pump to the fuel injection nozzle .
The fuel pressure change rate in the crank angle range is determined, and the environmental condition in the fuel system is determined from the fuel pressure change rate. Therefore, in each fuel injection, the predetermined pressure immediately before the fuel injection is determined based on the fuel pressure actually detected in the fuel system.
The fuel pressure change rate in the fuel angle range is obtained, and from the fuel pressure change rate, the fuel property at the time, the temporal change of the fuel system, and the environmental state in the fuel system that reflects these in a composite manner are determined. . As a result, the amount of change that has an effect on the control of fuel injection, such as aging of the fuel system and fuel properties, is used as a composite correlation value of various conditions in the fuel system. It has an excellent effect that it can be determined in a reliable manner.

[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 diagram showing a supercharged diesel engine system according to an embodiment of the present invention.

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

FIG. 4 is a block diagram showing a configuration of an ECU in one embodiment.

FIG. 5 is a flowchart showing a processing content of an “in-fuel-environment constant calculation routine” executed by an ECU in one embodiment.

FIG. 6 is a time chart showing the behavior of the fuel pressure and its one-time differential value during one fuel injection in one embodiment.

FIG. 7 is a flowchart showing the processing content of a “fuel injection amount control routine” executed by an ECU in one embodiment.

FIG. 8 is a flowchart showing the processing content of a “fuel injection timing control routine” executed by the ECU in one embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Fuel injection pump, 4 ... Fuel injection nozzle, 37 ... Pressure sensor (37 comprises fuel pressure detection means), 7
1. ECU (71 constitutes a fuel pressure change rate calculating means and a fuel system environment determining means.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) F02D 41/38 F02D 45/00

Claims (1)

(57) [Claims] A fuel injection nozzle that is opened by fuel pressure; a fuel injection pump for pumping fuel to the fuel injection nozzle; and a fuel pressure in a fuel system from the fuel injection pump to the fuel injection nozzle. And a fuel pressure for calculating a change rate of the fuel pressure in a predetermined crank angle range immediately before fuel injection based on a detection result of the fuel pressure detecting means. A fuel system environment comprising: a change rate calculating means; and a fuel system environment determining means for determining an environmental state in the fuel system based on a calculation result of the fuel pressure change rate calculating means. Judgment device.