JP3082187B2 - Fuel injection control system for diesel engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection amount control device for a diesel engine, and more particularly to a fuel injection amount control device for a diesel engine that controls the fuel injection amount by controlling the driving of a spill valve.

[0002]

2. Description of the Related Art Conventionally, in a fuel injection pump of an electronically controlled diesel engine, a pressurized fuel overflows at a predetermined time (hereinafter referred to as "spill"), so that a plunger of the fuel injection pump is used. The fuel injection amount obtained according to the lift amount is adjusted so as to be a target value.
Specifically, for example, an electromagnetic spill valve is controlled to open the spill port. Thus, the fuel from the plunger high-pressure chamber is spilled into the combustion chamber, and the end of the fuel pumping, that is, the end of the fuel injection, is controlled to obtain a predetermined fuel injection amount.

In such an electromagnetic spill valve, a required spill angle is usually determined by a signal, for example, an engine rotation pulse, which is synchronized with the plunger lift timing and is input at every constant pump rotation angle. The electromagnetic spill valve is configured to perform on / off control based on the angle. As an example of this type of configuration, Japanese Patent Publication No. 7-1
No. 8376 discloses a diesel engine fuel injection amount control method. According to this configuration, in order to obtain a fuel injection amount determined according to the current operating state, a target spill position corresponding to the fuel injection timing is obtained. The electromagnetic spill valve is opened to open the spill port. Here, the “target spill position” is calculated by calculating the spill position (angle) at which the electromagnetic spill valve should open from the engine speed and the accelerator opening, and dividing this angle by the angle per tooth of the rotation angle gear. The pulse count number of the angle and the remainder of the calculation result are calculated and determined. The remainder angle, which is the remainder of the calculation result, is time-converted based on the required time for one pulse including the previous spill position (spill-time pulse time).

[0004]

However, in the system disclosed in Japanese Patent Publication No. 7-18376, when the rotation fluctuation of the engine is large, the difference in the pulse time at the time of spill becomes large. For example, if the instantaneous rotation speed at the current target spill position is extremely reduced compared to the instantaneous rotation speed around the previous spill position, the current spill pulse time is longer than the previous spill time pulse. Become.
Therefore, if the surplus angle is converted into time based on the previous spill pulse time obtained in such a state where the rotation fluctuation is large, the error of the time conversion becomes very large and the accuracy of the fuel injection amount control deteriorates. May be caused. Also, due to the deterioration of the accuracy of the fuel injection amount control,
There is also a risk that the rotation of the engine will be further induced to lower the output.

An object of the present invention is to provide a fuel injection amount control device for a diesel engine which improves the accuracy of fuel injection amount control without being affected by engine speed fluctuations.

[0006]

The present invention for solving the above problems employs the means described in claim 1. According to this means, since the pulse time calculating means A7 and the pulse time storing means A8 are provided as shown in FIG. 1, the pulse time calculated by the pulse time calculating means A7 is stored in the pulse time storing means A8. I can put it. For this reason, the prediction reference time calculation means A9 sets the prediction reference time as
The engine rotation pulse (including the spill position required this time)
Below, it is called "pulse at spill". ) The engine before
The pulse time of the rotation pulse can be used. What
Contact us for 90 ° CA before top dead center of engine compression.
Any pulse at least one before the pill pulse
It is also conceivable to use time.

The above-mentioned compression top dead center represents the top dead center during the compression stroke of the top dead center during the compression stroke or the exhaust stroke. Here, the aforementioned engine rotation fluctuation is
It does not occur suddenly from a certain engine rotation pulse, but occurs successively depending on the engine state. Therefore, the pulse time of the engine rotation pulse including the spill position (pulse time at spill time) and the pulse time of the engine rotation pulse immediately before the pulse at spill time have similar values but cannot be the same time. Therefore, the surplus angle calculating means A6 based on the required spill angle calculated by the required spill angle calculating means A4 by the predicted coefficient calculating means A10, the post-spill time calculating means A14, the predicted coefficient updating means A15 and the predicted time calculating means A11. The difference between the calculated surplus angle and the opening time timing of the spill valve A2 controlled by the spill valve control means A13 based on the surplus angle time calculated by the surplus angle time conversion means A12, and corrects and updates the prediction coefficient. can do. Thus, by correcting the error between the spill time pulse time and the pulse time of the engine rotation pulse immediately before the spill time pulse, the predicted time of the spill time pulse time can be obtained extremely accurately. Therefore, by calculating the surplus angle based on the predicted time, the surplus angle time can be obtained with higher accuracy, and there is an effect of improving the accuracy of the fuel injection amount control.

Further, the rotation of the engine generally fluctuates with the fluctuation of the cycle of the engine. Therefore, paying attention to the variation of the fluctuation, the fluctuation of the fluctuation is large in the explosion stroke due to the difference in the compression ratio and the combustion state of each cylinder. However, in the compression stroke, since the rotation is performed only by the inertial force not depending on the explosive force of the engine, there is little variation factor and the rotation is relatively stable. Therefore, it is desirable that the prediction reference time be a pulse time during this compression stroke (for example, in the case of a four-cylinder engine, between 90 ° CA before compression top dead center and compression top dead center). The pulse time during this compression stroke is stable when viewed from cylinder to cylinder due to differences in compression ratio and mechanical sliding friction between cylinders, but may differ slightly when compared to other cylinders. is there. In order to eliminate the prediction time error due to such variations, the prediction coefficient and the prediction reference time are stored and calculated for each cylinder, which has the effect of enabling more accurate fuel injection amount control.

Further, by further approximating the calculation result of the prediction coefficient by the prediction coefficient calculation means, the difference between the spill pulse time and the prediction time can be suppressed.
In this approximation process, it is desirable that the approximation result is different depending on whether the prediction coefficient is increased or decreased.For example, by changing the approximation coefficient, compared with the case where the approximation coefficient is not changed, during the transition and the idling operation, The difference between the spill pulse time and the predicted time can be kept very small. This has the effect of suppressing engine speed fluctuations. Further, this approximation processing is not limited to using a predetermined value as the approximation coefficient, and is more preferably performed based on at least one of the rotational speed of the diesel engine, the accelerator angle, and the fuel injection amount.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment in which the present invention is applied to a fuel injection amount control device for a turbocharged diesel engine is shown in FIGS.
As shown in FIG. FIG. 2 is a schematic configuration diagram showing a fuel injection amount control device for a supercharged diesel engine in the present embodiment, and FIG. 3 is a cross-sectional view showing the distribution type fuel injection pump 1.

The fuel injection pump 1 has a drive pulley 3 which is drivingly connected to a crankshaft 40 of the diesel engine 2 via a belt or the like. Then, the fuel injection pump 1 is driven by the rotation of the drive pulley 3, and the fuel is pressure-fed to each fuel injection nozzle 4 provided for each cylinder (four cylinders in this embodiment) of the diesel engine 2 to perform fuel injection. .

The drive pulley 3 includes a drive shaft 5
A fuel feed pump (developed at 90 degrees in FIG. 2) 6 composed of a vane type pump is provided in the middle of the drive shaft 5. 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, the same number as the number of cylinders of the diesel engine 2, that is, in this embodiment, four cutting teeth are formed at equal angular intervals. Further, between each incisor, the crank angle is 3.7.
The protrusions are formed at equal angular intervals every 5 degrees. 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, and a plurality of cam rollers 10 facing the cam face 8a of the cam plate 8 are mounted along the circumference of the roller ring 9. ing. The number of cam faces 8a is equal to the number of cylinders of the diesel engine 2 (four in this embodiment). The cam plate 8 is always biased and engaged with the cam roller 10 by the spring 11.

A base end of a fuel pressurizing plunger 12 is integrally rotatably attached to the cam plate 8, and the cam plate 8 and the plunger 12 are rotated in conjunction with the rotation of the drive shaft 5. 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 engaged with the cam roller 10 while rotating, and reciprocates left and right in FIG. 2 by the same number as the number of cylinders. Driven. Further, the plunger 12 is reciprocally driven in the same direction while rotating with the reciprocating motion. That is, the plunger 12 moves forward or lifts while the cam face 8a of the cam plate 8 rides on the cam roller 10 of the roller ring 9, and conversely, the plunger 1 moves while the cam face 8a moves down the cam roller 10.
2 is reactivated.

The plunger 12 includes a pump housing 13
And a high-pressure chamber 15 is provided between the front end surface of the plunger 12 and the bottom surface of the cylinder 14.
It has become. In addition, the same number of intake grooves 16 and distribution ports 17 as the number of cylinders of the diesel engine 2 are formed on the outer periphery of the distal end side of the plunger 12. Furthermore, these suction grooves 1
A distribution passage 18 and a suction port 19 are formed in the pump housing 13 corresponding to the distribution port 6 and the distribution port 17.

When the fuel feed pump 6 is driven by the rotation of the drive shaft 5, the fuel chamber 21 is supplied from a fuel tank (not shown) through a fuel supply port 20.
Is supplied with fuel. Further, during the suction stroke in which the plunger 12 is moved back and the high-pressure chamber 15 is depressurized, one of the suction grooves 16 communicates with the suction port 19, so that fuel is introduced from the fuel chamber 21 into the high-pressure chamber 15. On the other hand, during the compression stroke in which the plunger 12 is reciprocated and the high-pressure chamber 15 is pressurized, the fuel is fed from the distribution passage 18 to the fuel injection nozzle of each cylinder and injected.

The pump housing 13 has a spill passage 2 for a fuel spill that connects the high-pressure chamber 15 to the fuel chamber 21.
2 are formed. In the middle of this spill passage 22,
An electromagnetic spill valve 23 as a spill valve for adjusting the fuel spill from the high-pressure chamber 15 is provided. The electromagnetic spill valve 23 is of a type that opens when de-energized and closes when energized. When the coil 24 of the electromagnetic spill valve 23 is de-energized, the valve 25 is opened and fuel in the high-pressure chamber 15 is released from the fuel chamber. 2
Spilled to 1. When the coil 24 is energized, the valve body 25 is attracted in the seating direction and the high-pressure chamber 15
The fuel spill from the fuel chamber 21 to the fuel chamber 21 is stopped.

Therefore, by controlling the energization time of the electromagnetic spill valve 23, the electromagnetic spill valve 23 is controlled to open and close, and the fuel spill from the high-pressure chamber 15 to the fuel chamber 21 is adjusted. Then, by opening the electromagnetic spill valve 23 during the compression stroke of the plunger 12, the fuel in the high-pressure chamber 15 is depressurized, so that the fuel injection from the fuel injection nozzle 4 is stopped. In other words, even when the plunger 12 moves forward, the fuel pressure in the high-pressure chamber 15 does not increase while the electromagnetic spill valve 23 is open, so that the fuel injection from the fuel injection nozzle 4 is not performed. Also, plunger 1
The amount of fuel from the fuel injection nozzle 4 is controlled by controlling the timing of the opening / closing valve of the electromagnetic spill valve 23 during the return movement of Step 2.

On the lower side of the pump housing 13, there is provided a timer device (deployed 90 degrees in FIG. 2) 26 for adjusting the fuel injection timing. The timer device 26 changes the position of the roller ring 9 with respect to the rotation direction of the drive shaft 5 so that the cam face 8 a
Is to change the timing of engagement with the cam roller 10, that is, the reciprocating drive timing of the cam plate 8 and the plunger 12.

The timer device 26 is driven by hydraulic pressure, and includes a timer housing 27, a timer piston 28 inserted into the timer housing 27, and a low-pressure chamber 29 located at one end of the timer housing 27. And a timer spring 31 that urges the pressure piston 30 toward the other end of the timer piston 28. The timer piston 28 is connected to the roller ring 9 via a slide pin 32.

In the pressurizing chamber 30 of the timer housing 27,
The fuel pressurized by the fuel feed pump 6 is introduced. The position of the timer piston 28 is determined by the balance between the fuel pressure and the urging force of the timer spring 31. Timer piston 28
Is determined, the position of the roller ring 9 is determined, and the reciprocating timing of the plunger 12 via the cam plate 8 is determined.

The timer device 26 is provided with a timing control valve 33 for adjusting the fuel pressure of the timer device 26, that is, the control oil pressure. That is, the pressurizing chamber 30 and the low-pressure chamber 29 of the timer housing 27 are communicated with each other by the communication path 34, and a timing control valve 33 is provided in the communication path 34. The timing control valve 33 is an electromagnetic valve whose opening and closing is controlled by an energization signal whose duty ratio is controlled. The fuel pressure in the pressurizing chamber 30 is adjusted by the opening and closing accuracy of the timing control valve 33. And
The lift timing of the plunger 12 is controlled by this fuel pressure, and the fuel injection timing from each fuel injection nozzle 4 is adjusted.

On the upper part of the roller ring 9, a rotation speed sensor 35 as an engine rotation detecting means comprising an electromagnetic pickup coil is mounted so as to face the outer peripheral surface of the pulser 7. The rotation speed sensor 35 detects the passage of a projection or the like of the pulsar 7 when it crosses, and detects a timing signal corresponding to the engine rotation speed NE, that is, at every predetermined crank angle (in this embodiment, at 3.75 ° CA). The engine rotation pulse is output as a rotation angle signal of the engine. Further, since the rotation speed sensor 35 is configured integrally with the roller ring 9,
Regardless of the control operation of the timer device 26, a reference timing signal is output at a pair of timings to the plunger lift.

Next, the diesel engine 2 will be described. In the diesel engine 2, a main combustion chamber 44 is formed for each cylinder by the cylinder 41, the piston 42, and the cylinder head 43. Also,
The main combustion chambers 44 are connected to sub combustion chambers 45 provided for the respective cylinders. The fuel injected from each fuel injection nozzle 4 is supplied to the sub combustion chamber 45. A glow plug 46 that functions as a start-up assist device is attached to each sub-combustion chamber 45.

The diesel engine 2 is provided with an intake pipe 47 and an exhaust pipe 50, and the intake pipe 47 is provided with a compressor 49 of a turbocharger 48 constituting a supercharger. Further, the exhaust pipe 50 is provided with a turbine 51 of a turbocharger 48. The exhaust pipe 50 is provided with a waste gate valve 52 for adjusting the supercharging pressure PiM. The turbocharger 48 rotates the turbine 51 by using the energy of the exhaust gas, and rotates the turbine 51 on the same axis as the compressor 4.
9 is rotated to increase the pressure of the intake air. Thus, a high-density air-fuel mixture is sent to the main combustion chamber 44 to burn a large amount of fuel, thereby increasing the output of the diesel engine 2.

The diesel engine 2 is provided with a recirculation pipe 54 for recirculating a part of the exhaust gas in the exhaust pipe 50 to the suction port 53 of the intake pipe 47. An exhaust gas recirculation valve (hereinafter, referred to as an “EGR valve”) 55 for adjusting the amount of exhaust gas recirculation is provided in the middle of the recirculation pipe 54. This EGR valve is a vacuum switching valve (hereinafter referred to as "VS
V ". The opening / closing is controlled by the control of 56).

Further, a throttle valve 58 which is opened and closed in conjunction with the depression amount of an accelerator pedal 57 is provided in the middle of the intake pipe 47. This throttle valve 5
A bypass path 59 is provided in parallel with 7, and a bypass throttle valve 60 is provided in the bypass path 59.
The opening and closing of the bypass throttle valve 60 is controlled by an actuator 63 having a two-stage diaphragm chamber driven by control of two VSVs 61 and 62. The bypass throttle valve 60 is controlled to open and close in accordance with various operating conditions. For example, during idle operation, the bypass throttle valve 60 is controlled to be half-open to reduce noise and vibration, and during normal operation, is controlled to be fully open. Sometimes it is controlled to a fully closed state for a smooth stop.

Then, as described above, the fuel injection pump 1
The electromagnetic spill valve 23, the timing control valve 33, the glow plug 46, and the VSVs 56, 61, 62 provided in the diesel engine 2 are electrically connected to an electronic control unit (hereinafter, referred to as "ECU") 71 described later. The ECU 71 controls the drive timings of the two.

As sensors for detecting each operating state, in addition to the rotation speed sensor 35, the following various sensors are provided. That is, an intake air temperature sensor 72 for detecting the intake air temperature THA near the air cleaner 64 is provided at the intake pipe 47.
And an accelerator opening sensor 73 for detecting an accelerator opening ACCP corresponding to the load on the diesel engine 2 from the open / close position of the throttle valve 58. Further, an intake pressure sensor 74 for detecting the intake air pressure after supercharging by the turbocharger 48, that is, the supercharging pressure PiM, is provided near the intake port 53. Further, a water temperature sensor 75 for detecting the cooling water temperature THW of the diesel engine 2 is provided. Furthermore, a crank angle sensor 76 for detecting the rotational position of the crankshaft 40 of the diesel engine 2, for example, the rotational position of the crankshaft 40 with respect to the top dead center of a specific cylinder is provided. Further, a transmission (not shown) has a magnet 77 rotated by rotation of the gear.
A vehicle speed sensor 77 is provided for detecting the vehicle speed SP by turning on / off the reed switch 77b in accordance with a.

The ECU 71 is connected to each of the above-described sensors 72 to 77, and also connected to the rotation speed sensor 35. In addition, the ECU 71 controls each sensor 3
5, the electromagnetic spill valve 23, the timing control valve 33, the glow plug 46, and the VSVs 56, 61, 62, etc. are suitably controlled based on the signals output from 72 to 77.

Next, the configuration of the ECU 71 will be described with reference to the block diagram of FIG. The ECU 71 includes a CPU 81 functioning as a central processing unit, a ROM 82 storing a predetermined control program, a map, and the like in advance, a CPU 8
ROM 83 for temporarily storing the result of operation 1 and the like, backup RAM 84 for storing previously stored data, clock 92 for generating a predetermined clock signal, and the like.
Are configured as logical operation circuits connected with each other.
The ECU 71 provides a required spill angle calculating means, a surplus angle calculating means, a pulse time calculating means, a pulse time storing means, a prediction reference time calculating means, a prediction coefficient calculating means, a predicted time calculating means, a surplus angle time converting means, The valve control means, the post-spill time calculating means and the prediction coefficient updating means are constituted.

The input port 85 is provided with the above-described intake air temperature sensor 72, accelerator opening sensor 73, intake air pressure sensor 74, and water temperature sensor 75 in the buffers 88, 89, 90, and 9 respectively.
1, are connected via a multiplexer 93 and an A / D converter 94. 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 95. Then, the CPU 81 reads, as input values, detection signals of the respective sensors, 35, 72 to 77, etc., which are input through the input port 85. In addition, the output port 86 is connected to the electromagnetic spill valve 23, the timing control valve 33, and the driving circuit 96, 97, 98, 99, 100, and 101 via the driving circuits 96, 97, 98, 99, 100, and 101, respectively.
The glow plug 46 and the VSVs 56, 61, 62 and the like are connected.

Then, the CPU 81 controls the sensors 35 and 72
Spill valve 2 based on input values read from
3. The timing control valve 33, the glow plug 46 and the VSVs 56, 61, 62 are suitably controlled. Next, the operation of the fuel injection amount control executed by the above-described ECU 71 will be described with reference to FIGS.

5 and 6 show the fuel injection time calculation processing and the prediction coefficient calculation processing executed by the ECU 71. The fuel injection time calculation process shown in FIG. 5 is executed as an NE interrupt routine that interrupts the rising timing of the engine speed pulse of the engine speed NE input from the speed sensor 35, and the prediction coefficient shown in FIG. The arithmetic processing is executed as a software interrupt routine called by the NE interrupt routine.

When the fuel injection time calculation processing shown in FIGS. 5 and 6 is started, first, in step 11 (hereinafter, FIG.
In FIG. 6 and FIG. 6, “step” is referred to as “S”. )
, The engine speed NE obtained based on the engine speed pulse output from the speed sensor 35 and the accelerator opening A obtained from the accelerator opening sensor 73
The fuel injection amount SPV is obtained based on the CCP and the like.

In the following step 12, step 1
The injection start position ANGSPS at which fuel injection is started based on the fuel injection amount SPV obtained at step 1, ie, the position at which the electromagnetic spill valve 23 is turned on, and the injection end position ANGSPE at which fuel injection ends, ie, the electromagnetic spill valve 23 is turned off. Calculate the spill position. This injection start position ANGSP
FIG. 7 shows the position of S and the injection end position ANGSPE. FIG. 7 shows the engine rotation pulse and the electromagnetic spill valve 2
FIG. 6 is a diagram showing an example of the operation of No. 3 in a correlated manner.

In step 12, the injection start position ANG
Injection end position ANGSP which is SPS and spill position
When E is obtained, a value required for calculating a prediction coefficient described later is stored in step 13. In step 14, the injection start position ANGSPS and the spill position ANGSPE
Pulse number CANGLa and remainder angle θ based on
REM is calculated.

Here, the spill pulse number CANGLa refers to the spill position A from the reference position, as shown in FIG.
The number of pulses up to one pulse before the engine rotation pulse including NGSPE (the fourth pulse corresponds to this in the present embodiment; this pulse is hereinafter referred to as a "spill time pulse"). The remainder angle θREM refers to a crank angle from the rising position of the spill pulse to the spill position ANGSPE. Further, in the present embodiment, the reference position is a pulse formed by a projection (teeth) formed next to the incisor formation position with the rotation of the pulser 7 in the engine rotation pulse output from the rotation speed sensor 35. It shall mean the rising position. (In this embodiment, the rising position of the 0th pulse is set as the reference position.) Now, assuming that the crank angle from the reference position to the spill position ANGSPE (hereinafter, this crank angle is referred to as “spill opening angle”) ANGSPV, The opening angle ANGSPV is the spill pulse number CANG described above.
It is expressed by the following equation (1) using La, a residual angle θREM, and a crank angle (3.75 ° CA) per one engine rotation pulse.

ANGSPV = 3.75 × CANGLa + θREM (1) In the following step 15, the pulse time TNINT (n−1) one pulse before (previous time) before the spill pulse is calculated. Since this pulse time TNINT (n-1) is the pulse width time of the engine rotation pulse (third pulse) immediately before the engine rotation pulse (fourth pulse) started by the current routine processing, the CPU 81 determines By subtracting the rising time T _3U of the third pulse from the rising time T _4U of the four pulses, the previous pulse time TNINT (n−
1) is calculated.

The pulse time TN calculated in step 15
INT (n-1) is stored in the RAM 83 in step 16.
And stored. Then, as described above, this routine processing is executed every time an engine rotation pulse is generated. Therefore, every time an engine rotation pulse is generated, the pulse time TNIN that is one time before the engine rotation pulse is generated.
T (n-1) is sequentially stored in the RAM 83, so that the pulse time TNINT for all engine rotation pulses is stored in the RAM 81.

In the following step 17, the estimated time T
SY is calculated. Here, TSY is calculated by multiplying the pulse time TNINT (n-1) immediately before the spill pulse by the prediction coefficient K. In the next step 18,
The remaining angle time TθREM is calculated. Here, the surplus angle time TθREM is the spill time pulse time TNINT (n).
(Hereinafter referred to as "spill time") can be expressed by the following equation (2).

TθREM = {θREM × TNINT (n)} / 3.75 (2) However, the actual spill pulse time TNINT (n)
Cannot be obtained unless the next engine rotation pulse (fifth pulse) after the spill pulse is generated. Also, the spill position ANGSP at the end of the fuel injection
Since E exists before the generation of the fifth pulse, it is necessary to calculate the remaining angle time TθREM before the generation of the fifth pulse. That is, the actual spill time TNINT
It is necessary to calculate before (n) is known.

Therefore, the spill pulse time TNIN required in the calculation of the remaining angle time TθREM
The prediction time TSY of T (n) is calculated by using the prediction coefficient K and TNINT
And configured to calculate using (n-1) and. The method of calculating the predicted time TSY and the calculation of the remaining angle time based on the predicted time are important parts of the present invention, and will be described in detail below.

First, a method of calculating the predicted time will be described. As the prediction reference time used as a reference for calculating the prediction time,
In this embodiment, the pulse time immediately before the spill pulse is used. This is because the engine rotation fluctuation does not suddenly occur from a certain engine rotation pulse, but occurs successively according to the state of the engine.Therefore, by using the pulse time immediately before the spill time pulse time, the characteristic of the engine rotation fluctuation is characterized. This is because it is possible to reflect the best. However, simply using the immediately preceding pulse time causes fluctuations in the engine rotation. Therefore, the pulse time of the engine rotation pulse including the spill position (pulse time at spill time) and the engine rotation time immediately before the pulse at spill time are used. Although the pulse time is close to the pulse time, it cannot be the same time, and an error occurs. Therefore, the prediction coefficient K is used to correct this error.

Next, a method of calculating a prediction coefficient will be described with reference to FIG. First, in step 21, the electromagnetic spill valve 2
The post-spill time TSPNE is calculated based on the time elapsed from the valve opening time of No. 3 to the next NE interrupt. FIG. 7 shows an example of the post-spill time TSPNE. In step 22, the post-spill time TSPNE calculated in step 21 and the residual angle θREM, which is the command value of the valve opening control of the electromagnetic spill valve 23, stored in step 13 are the values θREM.
The prediction coefficient update coefficient KD is calculated using the OL and the stored value TSYOL of the prediction time TSY used in the calculation of the remaining angle time TθREM as the control value. In KD = (θREMOL / 3.75) + (TSPNE / TSYOL) ·· (3) the following step 23, the prediction coefficient update coefficient K D of determining whether greater than 1. Prediction coefficient update coefficients K if D is greater than 1 (YES), the process proceeds to step 24, if the prediction coefficient update coefficient K D is not greater than 1 (N
O) The process proceeds to a step S25. Then, in step 24, the prediction coefficient K is updated so as to increase, and in step 25, the prediction coefficient K is updated so as to decrease. The reason why the approximation coefficient is changed between the process of increasing the prediction coefficient K (step 24) and the process of decreasing the prediction coefficient K (step 25) is based on experimental results. In this way, by changing the approximation coefficient, the difference between the pulse time during spill and the predicted time during transient and idling operation can be extremely small as compared with the case where the approximation coefficient is not changed. The effect of suppressing fluctuation has been confirmed by experiments.

Here, the approximation coefficient is set to a predetermined value in advance, but the method of determining the approximation coefficient is not limited to this. For example, when the engine speed is low (particularly during idling operation), the approximation coefficient is determined. The coefficient may be set to be large so that the coefficient becomes smaller as the rotation speed increases. In addition, the transient state of the engine is determined from a change in the accelerator opening or the engine speed, and if the engine is determined to be in the transient state, the approximation coefficient is set to a small value including 1 to follow the prediction coefficient. The delay may be reduced.

Further, it may be set that the determination of the transient state is made based on the change in the fuel injection amount instead of the change in the accelerator opening and the engine speed. As described above, the required spill angle θ REM and the difference between the actual spill timing are detected by the time from the spill to the next NE pulse, and the prediction coefficient for calculating the prediction time is corrected and updated, thereby achieving extremely accurate spill. The time pulse time can be predicted.

In the present embodiment, the prediction coefficient is a value that is sequentially updated regardless of the cylinder. However, by setting this value for each cylinder, the difference in the compression ratio for each cylinder, the mechanical sliding friction, etc. Thus, it is possible to accurately predict the pulse time at the time of spill without depending on a difference in engine rotation between cylinders due to a difference in engine speed. The residual angle time TθREM calculated in step 18 is set in the time counter in step 19 based on the thus calculated prediction coefficient K and prediction time TSY, and the spill pulse number CANGLa calculated in step 14 is calculated in the angle counter. Is set to

Next, in step 20, the pulse No.
Angle time TθRE from the time when becomes CANGLa
The injection is ended by opening the electromagnetic spill valve 23 after the lapse of M. Since the remaining angle time TθREM is very close to the actual remaining angle time as described above, according to the control of the present embodiment for controlling the electromagnetic spill valve 23 based on the remaining angle time TθREM, the combustion injection The amount can be controlled with high accuracy.

Further, for example, when an inner cam type fuel injection pump capable of pressurizing the fuel at a higher pressure is employed instead of the so-called face cam type fuel injection pump employed in the present embodiment, the fuel pressure increases. As a result, it becomes necessary to more accurately perform on / off control of the electromagnetic spill valve 23. That is, as the fuel pressure rises, the injection amount per unit time injected from the fuel injection nozzle 4 increases, so that the injection is performed only when the on / off timing of the electromagnetic spill valve 23 is slightly shifted from the predetermined timing. That is, the fuel amount greatly differs from the calculated predetermined injection amount. In this case, optimal engine control becomes impossible, resulting in deterioration of emission and large fluctuations in engine rotation.

On the other hand, the fuel injection amount control device according to the present embodiment can set the remaining angle time TθREM with extremely high accuracy, so that the on / off timing of the electromagnetic spill valve 23 can be set with high accuracy. Therefore, by adopting the configuration of the present embodiment, the fuel injection amount control can be reliably performed even when the fuel injection pump that supplies a high fuel pressure as described above is employed.

In the above-described embodiment, the remaining angle θREM is converted into a time to obtain the remaining angle time TθREM, and the OFF timing of the electromagnetic spill valve 23, that is, the spill position is set with high accuracy. However, this processing may be applied to the injection start position ANGSPS to set the timing of turning on the electromagnetic spill valve 23 with higher accuracy. With this configuration, it is possible to set both the ON timing and the OFF timing of the electromagnetic spill valve 23 with high accuracy, and it is possible to control the fuel injection amount with high accuracy particularly in the fuel injection pump having a high fuel pressure as described above. Become.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing the principle of the present invention.

FIG. 2 is a schematic configuration diagram showing a fuel injection amount control device for a supercharged diesel engine according to one embodiment of the present invention.

FIG. 3 is an enlarged sectional view showing a fuel injection pump according to one embodiment of the present invention.

FIG. 4 is a block diagram showing a configuration of an ECU according to one embodiment of the present invention.

FIG. 5 is a flowchart illustrating a fuel injection time calculation process executed by the ECU according to the embodiment.

FIG. 6 is a flowchart illustrating a process of updating a prediction coefficient of a pulse time at the time of spill executed by the ECU of the embodiment.

FIG. 7 is an explanatory diagram showing how to calculate a pulse time, a fuel injection time, a prediction coefficient, and the like during spilling according to the embodiment.

[Explanation of symbols]

 Reference Signs List 1 fuel injection pump 2 diesel engine 4 fuel injection nozzle 7 pulser 22 spill passage 23 electromagnetic spill valve (spill valve) 35 rotation speed sensor (engine rotation detection means) 40 crankshaft 71 ECU 73 accelerator opening sensor 76 crank angle sensor 81 CPU 82 ROM 83 RAM SPV Fuel injection amount ANGSPS Injection start position ANGSPE Injection end position CANGLa Number of pulses during spill θREM Extra angle TθREM Extra angle time TSPV Fuel injection time

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-7-139412 (JP, A) JP-A-5-288110 (JP, A) JP-A-7-317589 (JP, A) JP-A 8- 296488 (JP, A) JP-A-8-284724 (JP, A) JP-A-5-332184 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) F02D 41/40

Claims (6)

(57) [Claims] 1. A fuel injection pump for pressurizing fuel by a driving force generated by a diesel engine, and pumping the pressurized fuel to the diesel engine while controlling an injection amount by a spill valve; and operating the diesel engine. A required spill angle calculating means for calculating a required spill angle of the spill valve corresponding to a fuel injection end timing based on a fuel injection amount determined according to a state; and outputting an engine rotation pulse for each constant crank angle of the diesel engine. An engine rotation detecting means for calculating a count number from a reference position of the engine rotation pulse to a current spill position and a remainder angle less than one pulse based on the required spill angle and the engine rotation pulse. Angle calculation means, and a pulse time for one pulse of the engine rotation pulse A pulse time calculation means for calculation, the pulse time storage means for storing the pulse time, the prediction reference for calculating the predicted reference time is a pulse time of the previous engine rotation pulses of the engine rotation pulses including a spill position obtaining this and time calculation means, prediction coefficient calculating means for calculating a prediction coefficient used to predict the pulse time of the spill position including the engine rotation pulses from the prediction reference time, from the predicted reference time and the prediction coefficients, the spill location and prediction time calculating means for calculating including the remainder angle prediction time of the pulse time including the engine rotation pulse, the predicted time much angle time conversion of the remainder angle for calculating the time-converted odd angle time based on Means, a count number from the reference position obtained from the extra angle time to the spill position, and the extra angle Spill valve control means for driving and controlling the spill valve according to a time determined based on the degree time, and measuring a post-spill time which is a time from a time when the spill valve is previously opened to a first detected engine rotation pulse. A post-spill time calculating means, and a prediction coefficient for correcting the prediction coefficient based on the predicted time at the previous spill calculated by the predicted time calculating means, the post-spill time, the surplus angle, and the crank angle of the diesel engine. A fuel injection amount control device for a diesel engine, comprising: updating means. 2. The apparatus according to claim 1, wherein the prediction coefficient is calculated for each cylinder of the diesel engine. 3. The fuel injection amount control device for a diesel engine according to claim 2 , wherein the predicted reference time is calculated for each cylinder of the diesel engine. Wherein said prediction coefficient calculating means, wherein, characterized in that the further approximation the computation result of the prediction coefficients
Item 4. The fuel injection amount control device for a diesel engine according to item 1, 2 or 3 . 5. The diesel engine fuel injection amount control device according to claim 4 , wherein an approximation result of the approximation process differs depending on whether the prediction coefficient is increased or decreased. Wherein said approximation processing, the speed of the diesel engine, an accelerator angle, claim 4, characterized in that is performed based on at least one of the fuel injection amount or
6. The fuel injection amount control device for a diesel engine according to claim 5 .