JP2800456B2 - Fuel injection timing 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 diesel engine applied to, for example, an automobile, and more particularly to an electronically controlled diesel engine having a fuel injection pump. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection timing control apparatus for a diesel engine, which controls a fuel injection timing by controlling a timer control valve and driving a timer by duty control.

[0002]

2. Description of the Related Art Conventionally, in a fuel injection pump of an electronically controlled diesel engine, a spill port is controlled by, for example, an electromagnetic spill valve or the like so that a fuel injection amount obtained according to a lift of a plunger thereof becomes a target value. I am trying to open it. Thereby, the fuel from the plunger high-pressure chamber overflows (spills), and the end of fuel pumping, that is, the end of fuel injection, is controlled, and the required fuel injection amount is controlled.

In such an electromagnetic spill valve, a target spill angle is usually converted into a time by a signal synchronized with the lift of the plunger and input at every constant pump rotation angle, for example, an engine rotation pulse and an average engine rotation speed. Then, the target spill time is determined, and the on / off control of the electromagnetic spill valve is performed based on the target spill time. or,
Regarding the control of the fuel injection timing, a roller ring provided for lifting the plunger in the fuel injection pump and a timer control valve (TCV) for driving a timer piston of a hydraulic timer engaged with the roller ring are duty controlled. It is done by doing.

However, when the duty of the TCV is controlled in order to obtain the target fuel injection timing, if the plunger is lifted by the roller ring during the valve opening period of the TCV, the hydraulic pressure from the timer pressurizing chamber is lost. Since it is possible, the rotation of the roller ring is allowed by the driving reaction force of the plunger lift, and the synchronization between the time-converted target spill timing and the plunger lift is shifted. Therefore, the fuel is spilled slightly earlier than the time when the fuel should be originally spilled, which may cause a shift in the fuel injection timing or the injection period from the fuel injection pump. In particular, if the TCV on / off driving frequency is small,
When the on-duty time per operation becomes longer to obtain the required duty ratio, and when the on-duty time matches the plunger lift timing, that is, when the on-duty time matches the generation of the driving reaction force of the roller ring, The deviation of the target spill timing as described above may increase, and the deviation of the fuel injection timing and the injection period may increase. On the other hand, it is conceivable to uniformly increase the drive frequency of the TCV, but in that case, the number of times of operation of the TCV is increased, and there is a problem that its reliability is not preferable.

To cope with this, for example, in Japanese Patent Publication No. 2-29859, while the duty ratio for the TCV drive is kept constant, the drive frequency is changed to the operating state of the engine (idle and idle). It is disclosed that the change is made in accordance with whether or not the vehicle is in a nearby operating state, that is, in response to a change in the engine speed.
That is, the TCV is turned on and off at a normal drive frequency of “20 Hz” in the normal operation state other than the idle state and the vicinity of the idle state, and the drive frequency is “40 Hz” which is higher than the normal drive frequency in the idle state and the vicinity of the idle state. And the TCV is turned on and off, and the on-duty time is set to half of the case of "20 Hz", so that the duty ratio is kept constant.

[0006]

However, according to the above-mentioned prior art, in the idling state and the driving state near the idling state, the driving frequency is higher than the normal driving frequency of "40 Hz".
When the CV is duty-controlled, the on-duty time is relatively short, so that it is difficult for the hydraulic pressure from the timer pressurizing chamber to escape. This is because a response delay due to oil pressure drop occurs in the oil pressure path from the timer pressurizing chamber side. for that reason,
As the engine speed drops, the TCV drive frequency becomes
When the frequency is changed from “0 Hz” to “40 Hz”, the TCV
Therefore, even if the same duty ratio is maintained, the advance amount of the fuel injection timing may be slightly increased.

Therefore, even if injection timing feedback control or the like is performed, the engine speed falls and T
Immediately after the CV drive frequency is changed from “20 Hz” to “40 Hz”, there is a possibility that the actual injection timing may be slightly advanced temporarily. Conversely, the engine speed increases and the drive frequency of the TCV changes from “40 Hz” to “20 Hz”.
Immediately after the change was made, the actual injection timing could be temporarily delayed. That is, when the drive frequency of the TCV is changed, the fuel injection timing and the injection period may suddenly change and become unstable.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and an object thereof is to provide a fuel injection control system which controls the fuel injection timing when the drive frequency of the timer control valve is changed. It is an object of the present invention to provide a diesel engine fuel injection timing control device capable of suppressing and stabilizing sudden changes in the fuel injection timing.

[0009]

In order to achieve the above object, according to the present invention, as shown in FIG. 1, a cam M3 is provided on a fuel injection pump M1 and interlocks with the rotation of a diesel engine M2. Plunger M5 which is reciprocally driven through the air and pressurizes fuel in the high-pressure chamber M4 for fuel injection
And a spill adjustment valve M6 that is opened and closed to adjust the end time of fuel pressurization in the high-pressure chamber M4 to adjust the fuel injection amount from the fuel injection pump M1, and adjusts the fuel spill from the high-pressure chamber M4. And a plunger M via a cam M3 to adjust the fuel injection timing from the fuel injection pump M1.
5, a timer M7 driven by oil pressure to change the reciprocating drive timing, and a timer control valve M8 duty-controlled to adjust the control oil pressure in the timer M7.
Operating state detecting means M9 for detecting an operating state including the rotational speed of the diesel engine M2; and a spill adjusting valve M6 for obtaining a required target injection amount determined based on a detection result of the operating state detecting means M9. Injection amount control means M10 for driving control and injection timing control means M1 for duty controlling timer control valve M8 to obtain a required target injection timing determined based on the detection result of operating state detection means M9.
1 and a driving frequency changing means M12 for changing the driving frequency of the timer control valve M8 in response to a change in the engine speed detected by the operating state detecting means M9. Timer control valve M8 changed by drive frequency changing means M12
There is provided a duty ratio correction means M13 for correcting the duty ratio command value for the same target injection timing in the injection timing control means M11 according to the drive frequency of.

[0010]

According to the above construction, as shown in FIG. 1, in the fuel injection pump M1, the plunger M5 is reciprocally driven via the cam M3 in conjunction with the rotation of the diesel engine M2, whereby the fuel is injected for fuel injection. Fuel pressurization is performed in the high-pressure chamber M4. During the operation of the diesel engine M2, the operating state detecting means M9 detects an operating state including the rotation speed of the diesel engine M2. Then, the injection amount control means M10 controls the opening and closing of the spill adjustment valve M6 in order to obtain a required target injection amount determined based on the detection result of the operation state detection means M9. Thereby, the end time of the fuel pressurization in the high-pressure chamber M4 is adjusted, the fuel spill from the high-pressure chamber M4 is adjusted, and the fuel injection amount from the fuel injection pump M1 is adjusted. Further, the injection timing control means M11 controls the duty of the timer control valve M8 in order to obtain a required target injection timing determined based on the detection result of the operation state detection means M9. Thereby, the control oil pressure in the timer M7 is adjusted, the reciprocating drive timing of the plunger M5 is changed via the cam M3, and the fuel injection timing from the fuel injection pump M1 is adjusted.

Further, the driving frequency changing means M12 changes the driving frequency of the timer control valve M8 according to the change in the engine speed detected by the operating state detecting means M9.
At this time, the duty ratio correction means M13 corrects the duty ratio command value for the same target injection timing in the injection timing control means M11 according to the drive frequency of the timer control valve M8 changed by the drive frequency change means M12.

Therefore, even if the drive frequency of the timer control valve M8 is changed, the duty ratio command value for the same target injection timing is corrected and changed accordingly, so that the drive frequency of the timer control valve is changed with the change in the engine speed. Immediately after is changed, the duty ratio command value does not change too much. Therefore, the shift of the fuel injection timing from the fuel injection pump M1 is not promoted, and the fuel injection timing does not suddenly change.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which a fuel injection timing control apparatus for a diesel engine according to the present invention is embodied in an automobile will be described in detail with reference to the drawings. FIG. 2 is a schematic configuration diagram showing a fuel injection timing control device for a supercharged diesel engine in this embodiment, and FIG. 3 is a sectional view showing the distribution type fuel injection pump 1. The fuel injection pump 1 includes a drive pulley 3 which is drivingly connected to a crankshaft 40 of the diesel engine 2 via a belt or the like. The fuel injection pump 1 is driven by the rotation of the drive pulley 3, and the fuel is injected under pressure to each fuel injection nozzle 4 provided for each cylinder (four cylinders in this case) of the diesel engine 2 to perform fuel injection. .

In the fuel injection pump 1, the drive pulley 3 is attached to a tip of a drive shaft 5.
In the middle of the drive shaft 5, there is provided a fuel feed pump (developed at 90 degrees in this figure) 6 composed of a vane type pump. Further, a disk-shaped pulser 7 is attached to the base end side of the drive shaft 5. The outer surface of the pulsar 7 has a diesel engine 2
In this case, four cutting teeth are formed at equal angular intervals, that is, four cutting teeth are formed at equal angular intervals, and between each cutting tooth, 14 (total of 56) projections are formed at equal angular intervals. I have. 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. I have. Cam face 8
a is provided as many as the number of cylinders of the diesel engine 2. The cam plate 8 is always urged and engaged with the cam roller 10 by the spring 11.

A base end of a fuel pressurizing plunger 12 is attached to the cam plate 8 so as to be integrally rotatable. 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 rotates and engages with the cam roller 10 to reciprocate in the left-right direction by the same number as the number of cylinders. Driven. Further, the plunger 12 is driven to reciprocate in the same direction while rotating with the reciprocation. That is,
The plunger 12 is moved forward (lift) 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 12 is moved back while the cam face 8a rides down the cam roller 10.

The plunger 12 is fitted into a cylinder 14 formed in a pump housing 13, and a high pressure chamber 15 is formed between a tip surface of the plunger 12 and a bottom surface of the cylinder 14.
It has become. Also, on the outer periphery of the tip side of the plunger 12,
The same number of intake grooves 16 and distribution ports 17 as the number of cylinders of the diesel engine 2 are formed. In addition, these suction grooves 16
And the pump housing 13 corresponding to the distribution port 17.
Is formed with a distribution passage 18 and a suction port 19.

When the drive shaft 5 is rotated and the fuel feed pump 6 is driven, fuel is supplied from a fuel tank (not shown) into the fuel chamber 21 via the fuel supply port 20. Also, during the suction stroke in which the plunger 12 is moved back and the high-pressure chamber 15 is depressurized, the suction groove 1
The fuel is introduced from the fuel chamber 21 to the high-pressure chamber 15 when one of the ports 6 communicates with the suction port 19. On the other hand, during the compression stroke in which the plunger 12 is moved forward and the high-pressure chamber 15 is pressurized, fuel is pressure-fed from the distribution passage 18 to the fuel injection nozzle 4 of each cylinder and injected.

The pump housing 13 is provided with a spill passage 22 for fuel spill that connects the high-pressure chamber 15 and the fuel chamber 21. An electromagnetic spill valve 23 as a spill adjusting valve for adjusting the fuel spill from the high-pressure chamber 15 is provided in the middle of the spill passage 22. The electromagnetic spill valve 23 is a normally open type valve. When the coil 24 is not energized (off), the valve body 25 is opened and fuel in the high-pressure chamber 15 is spilled to the fuel chamber 21. When the coil 24 is energized (turned on), the valve body 25 is closed, and the spill of fuel from the high-pressure chamber 15 to the fuel chamber 21 is stopped.

Therefore, by controlling the energizing time of the electromagnetic spill valve 23, the valve 23 is controlled to close and open, and the spill amount of fuel 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 reduced in pressure, and the fuel injection from the fuel injection nozzle 4 is stopped. That is, 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, and the fuel injection from the fuel injection nozzle 4 is not performed. Further, during the forward movement of the plunger 12, by controlling the timing of closing and opening the electromagnetic spill valve 23, the amount of fuel injected from the fuel injection nozzle 4 is controlled.

Below the pump housing 13, there is provided a timer device (expanded at 90 degrees in this figure) 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, thereby changing the timing at which the cam face 8a engages with the cam roller 10, that is, the reciprocating drive timing of the cam plate 8 and the plunger 12. It is for.

The timer device 26 is driven by hydraulic pressure, and includes a timer housing 27, a timer piston 28 fitted in the housing 27, and a timer housing 27. A timer spring 31 for urging the piston 28 toward the other pressurizing chamber 30 is provided. 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. Further, the position of the roller ring 9 is determined by determining the position of the timer piston 28, and the plunger 1 is moved through the cam plate 8.
2 is determined.

The timer device 26 is provided with a timer control valve (TCV) 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 by the communication passage 34, and the TCV 33
Is provided. The TCV 33 is an electromagnetic valve whose opening and closing are controlled by a duty-controlled energization signal.
By controlling the opening and closing of the TCV 33, the fuel pressure in the pressurizing chamber 30 is adjusted. And by the fuel pressure adjustment,
The lift timing of the plunger 12 is controlled, 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 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 a projection or the like of the pulsar 7 when they cross, and outputs a timing signal (engine rotation pulse) corresponding to the engine speed NE. Further, since the rotation speed sensor 35 is integrated with the roller ring 9, the rotation speed sensor 35 outputs a reference timing signal to the plunger lift at a constant timing regardless of the control operation of the timer device 26.

Next, the diesel engine 2 will be described. In the diesel engine 2, a main combustion chamber 44 corresponding to each cylinder is formed by the cylinder 41, the piston 42, and the cylinder head 43. or,
Each of the main combustion chambers 44 is connected to a sub-combustion chamber 45 provided correspondingly for each cylinder. Then, the fuel injected from each fuel injection nozzle 4 is supplied to each sub combustion chamber 45. Further, a well-known glow plug 46 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. The intake pipe 47 is provided with a compressor 49 of a turbocharger 48 constituting a supercharger, and the exhaust pipe 50 is provided with a turbocharger. 48
Turbine 51 is provided. Further, a waste gate valve 5 for adjusting the supercharging pressure PiM is provided in the exhaust pipe 50.
2 are provided. As is well known, the turbocharger 48 uses the energy of the exhaust gas to rotate the turbine 51, and rotates the compressor 49 on the same axis to increase the pressure of the intake air. Thus, a high-density air-fuel mixture is sent into 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 has an exhaust pipe 5
A recirculation pipe 54 is provided for recirculating a part of the exhaust gas in the cylinder 0 to the suction port 53 of the intake pipe 47. An exhaust gas recirculation valve (EGR valve) 55 for adjusting the amount of exhaust gas recirculation is provided in the middle of the recirculation pipe 54. The opening and closing of the EGR valve 55 is controlled by the control of a vacuum switching valve (VSV) 56.

Further, a throttle valve 58 is provided in the middle of the intake pipe 47 so as to open and close in accordance with the amount of depression of an accelerator pedal 57. Also, its throttle valve 5
A bypass passage 59 is provided in parallel with 8, and a bypass throttle valve 60 is provided in the bypass passage 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 opening and closing of the bypass throttle valve 60 is controlled in accordance with various operation states. For example, it is controlled to a half-open state during idle operation to reduce noise and vibration, to a fully opened state during normal operation, and to a fully closed state during smooth operation to stop smoothly.

The electromagnetic spill valve 2 provided in the fuel injection pump 1 and the diesel engine 2 as described above
3, TCV33, glow plug 46 and each VSV56,
Reference numerals 61 and 62 are electrically connected to electronic control units (hereinafter simply referred to as “ECUs”) 71 constituting injection amount control means, injection timing control means, drive frequency changing means and duty ratio correction means, respectively. The drive timings are controlled.

As sensors constituting the operating state detecting means, the following various sensors are provided in addition to the rotation speed sensor 35. That is, an intake air temperature sensor 7 for detecting an intake air temperature THA near the air cleaner 64 is provided in the intake pipe 47.
2 are provided. Further, an accelerator opening sensor 73 for detecting the accelerator opening ACCP corresponding to the load of the diesel engine 2 from the open / close position of the throttle valve 58 is provided. An intake pressure sensor 74 for detecting the intake air pressure after being supercharged by the turbocharger 48, that is, the supercharging pressure PiM, is provided near the intake port 53. Further, the cooling water temperature THW of the diesel engine 2
Is provided. Further, a crank angle sensor 76 for detecting a rotation reference position of the crankshaft 40 of the diesel engine 2, for example, a rotation position of the crankshaft 40 with respect to a top dead center of a specific cylinder is provided.
Further, in a transmission (not shown), a reed switch 77b is turned on / off by a magnet 77a which is rotated by the rotation of the gear, so that the vehicle speed (vehicle speed) S
A vehicle speed sensor 77 for detecting P is provided.

The ECU 71 is connected to the sensors 72 to 77 described above, respectively,
5 is connected. In addition, the ECU 71 controls each sensor 35,
The electromagnetic spill valve 23, the TCV 33, the glow plug 46 and the VSV 5
6, 61, 62, etc. are suitably controlled. Next, the aforementioned E
The configuration of the CU 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, and a random access memory (RAM) 8 that temporarily stores calculation results and the like of the CPU 81.
3. Backup RA for storing pre-stored data
It is configured as a logical operation circuit in which the M84 and the like and these units and the input port 85 and the output port 86 are connected by the bus 87.

The input port 85 is provided with the above-described intake air temperature sensor 72, accelerator opening sensor 73, intake pressure sensor 74, and water temperature sensor 75 in buffers 88, 89, 90, and 9, respectively.
1, a multiplexer 93 and an A / D converter 94. Similarly, the input port 85 is connected to the rotation speed sensor 35, the crank angle sensor 76, and the vehicle speed sensor 77 via a waveform shaping circuit 95. Then, the CPU 81 reads, as input values, detection signals of the sensors 35, 72 to 77, etc., which are input through the input port 85. Each drive circuit 9 is connected to the output port 86.
6, 97, 98, 99, 100, 101, the electromagnetic spill valve 23, the TCV 33, the glow plug 46 and the VSV.
56, 61, 62, etc. are connected.

Then, the CPU 81 controls the sensors 35 and 72
Based on the input value read from ~ 77, the electromagnetic spill valve 2
3, TCV33, glow plug 46 and VSV56,6
1, 62, etc. are suitably controlled. Next, the ECU 7
The processing operation of the fuel injection timing control executed by 1 will be described with reference to flowcharts shown in FIGS. 5, 8 and 9 and time charts shown in FIGS.

First, the flowchart shown in FIG.
71, the fuel injection pump 1
TC to adjust the control oil pressure in the timer device 26
On-duty time F for duty control of V33
This is a processing routine for calculating SDUTY, which is executed at an interrupt every time an engine rotation pulse from the rotation speed sensor 35 is input.

When the process proceeds to this routine, first, at step 101, the engine speed NE is read based on the detection value of the speed sensor 35. Subsequently, in step 102, based on the engine rotation pulse obtained from the detection value of the rotation speed sensor 35, the interruption pulse counter CNIRQ of the engine rotation speed NE adds "1" to the spill reference pulse number CANGL corresponding to the injection end timing. It is determined whether or not the number of pulses has reached. That is, it is determined whether the fuel injection has been completely completed. For example, FIG.
As shown in the figure, the spill reference pulse number CANGL is "4".
In this case, the value of the interrupt pulse counter CNIRQ that completes the fuel injection is “5”.

If the fuel injection has not been completely completed, the subsequent processing is temporarily terminated. On the other hand, when the fuel injection is completely completed, the process proceeds to the next step 103. Then, in step 103, it is determined whether or not an on / off switching counter CTCV for instructing on / off switching of the TCV 33 is "0". The on / off switching counter CTCV is set according to the magnitude of the engine speed NE in step 106 described later.

Here, the on / off switching counter CTCV
Is not "0", in step 104, a result obtained by subtracting "1" from the value of the on / off switching counter CTCV is set as a new value of the on / off switching counter CTCV, and the subsequent processing is temporarily terminated. I do. In step 103, the on / off switching counter CTCV
Is "0", in step 105, as shown in FIG. 7, the on-time TON of the TCV 33 is set, and the TCV 33 is turned on and opened.

Subsequently, at step 106, the value of the above-mentioned on / off switching counter CTCV is set according to the magnitude of the engine speed NE. That is, if the engine speed NE is less than "1200 rpm", the value of the on / off switching counter CTCV is set to "1", and the engine speed NE is equal to or more than "1200 rpm" and less than "2400 rpm". In this case, the value of the on / off switching counter CTCV is set to “2”, and when the engine speed NE is “2400 rpm” or more, the value of the on / off switching counter CTCV is set to “4”. .

Therefore, the on / off switching counter CTCV
Is set to "1", for example, as shown in FIG. 7, the ON time TON is set every time the fuel injection is completed once and the "CANGL + 1" th engine rotation pulse is input and started. . When the on / off switching counter CTCV is set to "2", the fuel injection is completed twice, and the "ONGL + 1" th engine rotation pulse immediately thereafter is input and the ON time TON is increased every time the engine starts. Set. Further, when the on / off switching counter CTCV is set to "4", the fuel injection is completed four times, and immediately after that, the "CANGL + 1" th engine rotation pulse is input and the ON time T is set.
ON is set.

That is, by opening the TCV 33 during the non-injection period after the end of the fuel injection, the spill timing due to the driving reaction force of the roller ring 9 is prevented from being shifted. Is driven, the drive frequency of the TCV 33 increases in accordance with the increase in the engine speed NE. Therefore, the drive frequency of the TCV 33 increases excessively at high engine speed, which is not preferable in terms of reliability. Therefore,
The drive frequency is further changed by changing the valve opening of the TCV 33 after the end of the second fuel injection and further after the end of the fourth fuel injection in accordance with the increase in the engine speed NE, thereby maintaining the drive frequency in an appropriate range. . In this embodiment, TCV33
In the case of a four-cylinder four-cycle engine, the on / off switching counter CTCV changes the driving frequency from "1" to "2" or from "2" to "1" according to the magnitude of the engine speed NE.
And from “2” to “4” or from “4” to “2”, respectively, from “40 Hz” to “20H”.
The frequency is switched from "z" or "20 Hz" to "40 Hz".

Next, at step 107, TCV3
On-duty time FS for duty control of 3
When calculating DUTY, a rotation speed correction term KSY used as a correction term based on the engine rotation speed NE is calculated. This rotation speed correction term KSY is calculated according to the following equation. KSY = (NE ÷ CTCV-600) ÷ 600 ×
0.15 + 0.85 That is, the rotation speed correction term KSY is
The set value of the on / off drive counter CTCV in step 106 is changed by the change in the engine speed NE, and the same actual injection timing is set by the timer device 26 in accordance with the engine speed NE when the drive frequency of the TCV 33 is changed. Is a correction value indicating how many duty ratio command values of the TCV 33 to be described later are corrected. Further, the value of the rotational speed correction term KSY is, for example, the value obtained when the engine rotational speed NE reaches “1200 rpm”
After the drive frequency of V33 is changed from "40 Hz" to "20 Hz", it changes linearly until it rises again to "40 Hz" with an increase in engine speed NE. Further, in the equation for calculating the rotation speed correction term KSY, the constant term “0.85” is obtained when the drive frequency of the TCV 33 is switched from “40 Hz” to “20 Hz”.
In order to hold the timer piston 28 of the timer device 26 at the same position, that is, to hold the timer position, the on-duty times FSDUTY need only be corrected to “85%”. Note that this constant “0.8
“5” is a value obtained by an experiment in advance, and is determined according to a difference in characteristics of the hydraulic path related to the timer device 26.

Further, at step 108, TCV3
In order to control the duty of No. 3, an on-duty time FSDUTY as shown in FIG. 7 is calculated. The on-duty time FSDUTY includes a target on-duty ratio FTDUTY separately obtained as a base value, a crank angle conversion time T180 for every 180 degrees separately obtained,
The value is obtained by multiplying the value of the previously set on / off switching counter CTCV by the previously obtained rotation speed correction term KSY. And the on-duty time FSDU
When the calculation of TY is completed, the subsequent processing is temporarily ended.

Here, in step 108, the target on-duty ratio FTDUTY used for calculating the on-duty time FSDUTY is determined according to the flowchart shown in FIG. This flowchart is based on the ECU 7
1 is a processing routine executed by a periodic interruption every 50 ms. That is, first, step 201
In, the engine speed NE is read based on the detection value of the speed sensor 35, and the final injection amount QFIN as a command value of the target injection amount separately obtained is read. Subsequently, in step 202, the read engine speed NE and the final injection amount QFIN are used.
A target crank angle timing TRGCA as a command value of the target injection timing is calculated with reference to a predetermined map (not shown).

Next, in step 203, the obtained target crank angle timing TRGCA is read, and the actual crank angle timing ACTCA as a separately obtained injection timing detection value is read. And step 20
4, the read actual crank angle timing ACT
Based on the difference between CA and the target crank angle timing TRGCA, a target on-duty ratio FTDUTY is calculated with reference to a predetermined map (not shown), and the subsequent processing is temporarily terminated.

The target on-duty ratio FTDUTY obtained in this manner is the same as the target crank angle timing TRGC.
This is a value constituting a duty ratio command value for A. Then, the target on-duty ratio FTDUTY is added to FIG.
In step 108 of the flowchart shown in FIG. 7, the crank angle conversion time T180, the on / off switching counter CT
The on-duty time FSDUTY taking into account the change in the drive frequency of the TCV 33 is calculated by multiplying the value of CV and the rotation speed correction term KSY.

On the other hand, the setting of the off time TOFF for turning off the TCV 33 as shown in FIG. 7 is performed according to the flowchart shown in FIG. This flowchart is a processing routine executed by the ECU 71.
It is executed by interruption every time the ON time TON of the CV 33 is set. That is, first, in step 301, the current time TN is read. Subsequently, in step 302, the on-duty time F is set at the current time TN.
The result of adding the SDUTY is set as the off time TOFF, and the TCV 33 is turned off and closed when the off time TOFF comes.

According to the above processing, the ON time TO of the TCV 33 is determined in accordance with the engine speed NE at each time.
N and OFF time TOFF are set, respectively, and TCV3
3 is duty-controlled. Therefore, in the fuel injection timing control device for a diesel engine of this embodiment, for example, when the engine speed NE increases from less than "1200 rpm" to "1200 rpm", the drive frequency of the TCV 33 changes from "40 Hz" to "20 Hz". Will be changed. When the drive frequency of the TCV 33 is "2
0 Hz ", and until the engine speed NE rises again to" 40 Hz "with an increase in the engine speed NE, taking into account the oil pressure drop response of the communication passage 34 due to a change in the drive frequency thereof, Duty time FSDUTY is TCV3
The correction is made in accordance with the change in the drive frequency of No. 3 and the change in the engine speed NE. That is, the on-duty time FSDUTY between the time when the drive frequency of the TCV 33 is changed to “20 Hz” and the time when the drive frequency rises again to “40 Hz” is reached.
Is linearly changed without becoming too large, so that the duty ratio command value of the TCV 33 is gradually changed linearly without sudden change.

Here, due to the structure of the timer device 26 and its hydraulic path, when the same fuel injection timing is maintained by the timer device 26, the higher the drive frequency of the TCV 33, the more difficult it is for the hydraulic pressure to escape, and the longer the on-duty time FSDUTY. There is a need to. On the other hand, as the drive frequency is lower, the hydraulic pressure is more likely to escape, and the on-duty time FSDUTY needs to be reduced. However, in this embodiment, since the duty ratio command value of the TCV 33 is gradually changed linearly during the change of the drive frequency as described above, the response delay of the oil pressure drop from the pressurizing chamber 30 of the timer device 26 is prevented. can do. As a result, the position of the timer piston 28 in the timer device 26, that is, the so-called timer position can be suitably held at a fixed position, and the fuel injection timing can be prevented from being retarded. That is, immediately after the drive frequency of the TCV 33 is changed from “40 Hz” to “20 Hz”, it is possible to prevent the actual fuel injection timing from being temporarily temporarily delayed.

On the contrary, the engine speed NE decreases and the drive frequency of the TCV 33 changes from “20 Hz” to “40”.
Hz, and falls again to “20 Hz”, the on-duty time FSDUTY of the TCV 33 is changed linearly without becoming too small. Therefore,
The duty ratio command value of the TCV 33 is gradually changed linearly, so that the response of the timer device 26 to the pressure drop from the pressurizing chamber 30 can be improved. As a result, the timer position can be suitably held at a fixed position, and the advance of the fuel injection timing can be prevented. That is, immediately after the drive frequency of the TCV 33 is changed from “20 Hz” to “40 Hz”, it is possible to temporarily prevent the actual fuel injection timing from being advanced earlier.

Therefore, when the drive frequency of the TCV 33 is changed, it is possible to suppress a sudden change in the fuel injection timing and the fuel injection period, and to stabilize them. Therefore, in this embodiment, when the drive frequency of the TCV 33 is changed, the fuel injection timing from the fuel injection pump 1 can be stabilized, so that the injection timing is not excessively advanced. As a result, unnecessary torque due to the advance angle is not generated, and generation of unnecessary vibration in the diesel engine 2 can be prevented.

Further, in the diesel engine 2, it is possible to prevent the generation of knock noise due to the advance of the fuel injection timing. Further, it is possible to prevent a wasteful increase in the combustion temperature due to the advance of the fuel injection timing, thereby preventing deterioration of the exhaust emission. In addition, T
Since there is no extra retardation of the fuel injection timing due to the change of the drive frequency of the CV 33, it is possible to prevent a useless decrease in the combustion temperature and thus to prevent a misfire.

It should be noted that the present invention is not limited to the above-described embodiment, and may be carried out as follows by appropriately changing a part of the configuration without departing from the spirit of the invention. (1) In the above embodiment, the electromagnetic spill valve 23 is used as the spill adjusting valve, but a piezo spill valve using a piezo element may be used. (2) In the above embodiment, the present invention is embodied in the diesel engine 2 having the turbocharger 48 as a supercharger.
It can be embodied as a diesel engine with a supercharger as a supercharger or a diesel engine without a supercharger.

[0054]

As described above in detail, according to the present invention, in the fuel injection pump, the fuel is pressurized in the high-pressure chamber by the plunger reciprocally driven in association with the rotation of the diesel engine, and the spill adjusting valve is provided. The fuel injection amount is adjusted by adjusting the fuel spill from the high-pressure chamber to adjust the end time of the fuel pressurization, and the hydraulic timer is driven by the timer control valve that is duty-controlled to reciprocate the plunger. By changing the timing, the fuel injection timing is adjusted, and in addition, the driving frequency of the timer control valve is changed in response to the change in the engine speed, so that the timer is changed in response to the change in the engine speed. The duty ratio command value for the timer control valve for the same target injection timing is corrected according to the drive frequency of the control valve. Excessive change in the duty ratio command value is suppressed when the driving frequency is changed, and suppressing the sudden change in fuel injection timing and injection period is exhibited an excellent effect that can be stabilized.

[Brief description of the drawings]

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

FIG. 2 is a schematic configuration diagram showing a fuel injection timing control device for a diesel engine according to an embodiment of the present invention;

FIG. 3 is a cross-sectional view illustrating a distribution type fuel injection pump according to one embodiment.

FIG. 4 is a block diagram illustrating a configuration of an ECU according to one embodiment.

FIG. 5 is a flowchart showing TC and TC executed by the ECU according to the embodiment;
9 is a flowchart illustrating a processing routine executed by an interrupt for each input of an engine rotation pulse for calculating an on-duty time of V.

FIG. 6 is a time chart for explaining a correspondence relationship between an engine rotation pulse, opening / closing of an electromagnetic spill valve, and a plunger lift in one embodiment.

FIG. 7 shows an engine rotation pulse and TCV in one embodiment.
5 is a time chart for explaining a correspondence relationship between on / off driving.

FIG. 8 is a flow chart showing the operation of the ECU according to the embodiment,
9 is a flowchart illustrating a processing routine executed by a periodic interruption every 50 ms for calculating a target on-duty time of V;

FIG. 9 is a flowchart showing TC and TC executed by the ECU according to the embodiment;
It is a flowchart explaining the processing routine performed by the interruption for every TC time ON time set for OFF time setting of V.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Fuel injection pump, 2 ... Diesel engine, 8 ... Cam plate, 9 ... Roller ring, 12 ... Plunger, 1
5 ... High pressure chamber, 23 ... Electromagnetic spill valve as spill adjustment valve, 26 ... Timer device, 33 ... Timer control valve (TC
V), 35... A rotational speed sensor constituting the operating state detecting means, 71. An EC constituting the injection amount controlling means, the injection timing controlling means, the driving frequency changing means and the duty ratio correcting means.
U.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) F02D 41/00-45/00 395 F02D 1/00-1/18

Claims (1)

(57) [Claims] 1. A fuel injection pump, which is reciprocally driven via a cam in association with the rotation of a diesel engine,
A plunger for pressurizing the fuel in the high-pressure chamber for fuel injection, and an open / close drive for adjusting the end timing of the fuel pressurization in the high-pressure chamber in order to adjust the fuel injection amount from the fuel injection pump. A spill adjustment valve that adjusts the fuel spill from the high pressure chamber, and is hydraulically driven to change the reciprocating drive timing of the plunger via the cam to adjust the fuel injection timing from the fuel injection pump. A timer, a timer control valve that is duty-controlled to adjust a control oil pressure in the timer, an operating state detecting means for detecting an operating state including a rotational speed of the diesel engine, and a detection result of the operating state detecting means. Injection amount control means for driving and controlling the spill adjustment valve to obtain a required target injection amount determined on the basis of a detection result of the operation state detection means. Injection timing control means for duty-controlling the timer control valve so as to obtain the required target injection timing determined in advance, and the timer control valve is controlled in response to a change in the engine speed detected by the operating state detection means. In a fuel injection timing control device for a diesel engine comprising a driving frequency changing unit for changing a driving frequency,
Duty ratio correction means for correcting a duty ratio command value for the same target injection timing in the injection timing control means according to a drive frequency of the timer control valve changed by the drive frequency change means is provided. Fuel injection timing control device for diesel engines.