JPH04347346A - Fuel injection timing controller of diesel engine - Google Patents

Abstract

PURPOSE:To suppress any rapid change of a fuel injection timing in the case of drive frequency change of a timer control valve. CONSTITUTION:Fuel pressurization is performed in a high pressure chamber 15 by a plunger 12 reciprocatingly drive by interlocking to a diesel engine, in a fuel injection pump 1, and the completion timing of the fuel pressurization is adjusted so as to provide a required fuel injection quantity by adjusting fuel spill from the high pressure chamber 15 by means of an electromagnetic spill valve 23. The required fuel injection timing is obtained by driving a hydraulic timer device 26 by a duty-controller TCV 33, and varying a reciprocating drive timing of the plunger 12. The drive frequency of the TCV 33 is varied in response to the variation of the engine speed. A duty-ratio command value of the TCV 33 with respect to the same target injection timing is so formed as to be corrected according to the variation in the drive frequency. Consequently, the duty-ratio command value is not varied excessively so that shift of the fuel injection timing can not be increased because it is just after the change of the drive frequency.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a diesel engine applied to, for example, an automobile, and more specifically, it is suitable for use in an electronically controlled diesel engine equipped with a fuel injection pump, and the amount of fuel injected from the fuel injection pump is controlled. The present invention relates to a fuel injection timing control device for a diesel engine that controls the fuel injection timing by controlling the duty of a timer control valve and driving a timer.

0002

[Prior Art] Conventionally, in a fuel injection pump for an electronically controlled diesel engine, a spill port is opened by controlling, for example, an electromagnetic spill valve, etc., so that the fuel injection amount obtained according to the lift of the plunger becomes a target value. I'm trying to open it up. Thereby, the fuel from the plunger high pressure chamber overflows (spills), and the end of pressure feeding of fuel, that is, the end of fuel injection, is controlled, and the required fuel injection amount is controlled.

[0003] In such an electromagnetic spill valve, the target spill angle is usually converted into time using a signal synchronized with the lift of the plunger and input at every fixed pump rotation angle, such as an engine rotation pulse and an average engine rotation speed. A target spill timing is determined, and the electromagnetic spill valve is controlled on/off based on the target spill timing. or,
Regarding control of fuel injection timing, duty control is applied to a roller ring provided in the fuel injection pump to lift the plunger and a timer control valve (TCV) that drives the timer piston of a hydraulic timer that engages with the roller ring. This is done by

However, when the TCV is duty-controlled to obtain the target fuel injection timing, if the plunger is lifted by the roller ring during the TCV opening period, hydraulic pressure may be released from the timer pressurizing chamber side. Since this is possible, rotation of the roller ring is allowed by the drive reaction force of the plunger lift, and the synchronization between the time-converted target spill timing and the plunger lift is lost. Therefore, the fuel is spilled at a slightly earlier time than the time when it should originally be spilled, which may cause a shift in the timing and period of fuel injection from the fuel injection pump. In particular, when the on-off driving frequency of the TCV is small, the on-duty time per cycle becomes long to obtain the required duty ratio, and when the on-duty time and the plunger lift timing match, that is, the on-duty time and When the generation of the driving reaction force of the roller ring coincides with the generation of the drive reaction force, there is a possibility that the deviation in the target spill timing as described above becomes large, and the deviation in the fuel injection timing or injection period becomes large. On the other hand, it is conceivable to uniformly increase the drive frequency of the TCV, but in that case, there is a problem that the number of times the TCV operates increases, which is not desirable in terms of reliability.

In order to deal with this problem, for example, Japanese Patent Publication No. 2-29859 discloses that while the duty ratio for TCV drive is held constant, the drive frequency is adjusted depending on the engine operating state (idle and idling). It is disclosed that the engine speed is changed depending on whether or not there is a nearby operating state, that is, depending on a change in engine speed. That is, in normal operating states other than idle and near idle, the TCV is driven on and off at the normal driving frequency of 20 Hz, and in idle and near idle operating states, the TCV is driven at a higher than normal driving frequency of 40 Hz. At the same time, the TCV is driven on and off, and the on-duty time is set to be half of that in the case of "20 Hz", thereby keeping the duty ratio constant.

[0006]

[Problems to be Solved by the Invention] However, in the technique disclosed in the above-mentioned prior art publication, in idle and near-idle operating conditions, the T
When the CV is duty-controlled, the on-duty time is relatively short, making it difficult for hydraulic pressure to escape from the timer pressurizing chamber side. This is because there is a delay in response to hydraulic pressure release in the hydraulic path from the timer pressurizing chamber side. Therefore,
As the engine speed decreases, the TCV drive frequency changes to "2".
When changing from "0Hz" to "40Hz", TCV
Even if the same duty ratio was maintained, there was a risk that the amount of advance of the fuel injection timing would increase slightly.

Therefore, even if injection timing feedback control or the like is performed, the engine speed decreases and T
Immediately after the CV drive frequency was changed from "20 Hz" to "40 Hz", there was a possibility that the actual injection timing would be temporarily advanced slightly. On the other hand, the engine speed increases and the TCV drive frequency changes from 40Hz to 20Hz.
Immediately after the change, there was a risk that the actual injection timing would be temporarily delayed. In other words, when the driving frequency of the TCV is changed, there is a risk that the fuel injection timing and injection period will suddenly change and become unstable.

The present invention has been made in view of the above-mentioned circumstances, and its object is to change the injection timing when the driving frequency of the timer control valve that is driven to control the fuel injection timing is changed. An object of the present invention is to provide a fuel injection timing control device for a diesel engine that can suppress sudden changes in fuel injection timing and stabilize the engine.

[0009]

[Means for Solving the Problems] In order to achieve the above object, in the present invention, as shown in FIG. A plunger M5 is reciprocated through the plunger M5 and pressurizes the fuel in the high pressure chamber M4 for fuel injection.
and a spill adjustment valve M6 that is driven to open and close to adjust the fuel spill from the high pressure chamber M4 in order to adjust the fuel injection amount from the fuel injection pump M1 and the end timing of fuel pressurization in the high pressure chamber M4. In order to adjust the timing of fuel injection from the fuel injection pump M1, a plunger M5 is inserted via a cam M3.
a timer M7 driven by hydraulic pressure to change the reciprocating drive timing of the timer M7; a timer control valve M8 duty-controlled to adjust the control hydraulic pressure in the timer M7;
Operating state detection means M9 for detecting the operating state including the rotational speed of the diesel engine M2, and its operating state detection means M
Injection amount control means M10 drives and controls the spill adjustment valve M6 to obtain the required target injection amount determined based on the detection result of step 9, and the required target injection amount determined based on the detection result of the operating state detection means M9. Injection timing control means M11 duty-controls the timer control valve M8 in order to obtain the injection timing, and a drive frequency that changes the drive frequency of the timer control valve M8 in response to changes in the engine rotation speed detected by the operating state detection means M9. In the fuel injection timing control device for a diesel engine, the fuel injection timing control device for a diesel engine includes a changing means M12, in which the duty ratio for the same target injection timing in the injection timing controlling means M11 is changed according to the driving frequency of the timer control valve M8 changed by the driving frequency changing means M12. A duty ratio correction means M13 for correcting the command value is provided.

0010

[Operation] According to the above structure, as shown in FIG. 1, in the fuel injection pump M1, the plunger M5 is interlocked with the rotation of the diesel engine M2 and is reciprocated via the cam M3, thereby for fuel injection. Fuel is pressurized in the high pressure chamber M4. Also, while operating diesel engine M2,
The operating state detection means M9 detects the operating state including the rotation speed of the diesel engine M2. Then, the injection amount control means M10 controls the spill adjustment valve M6 to obtain the required target injection amount determined based on the detection result of the operating state detection means M9.
Controls opening/closing drive. As a result, the end timing of fuel pressurization in the high pressure chamber M4 is adjusted, fuel spill from the high pressure chamber M4 is adjusted, and the amount of fuel injected from the fuel injection pump M1 is adjusted. Further, the injection timing control means M11 performs duty control on the timer control valve M8 in order to obtain the required target injection timing determined based on the detection result of the operating state detection means M9. As a result, 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 in response to a change in the engine rotational 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 driving frequency of the timer control valve M8 changed by the driving frequency changing means M12.

Therefore, even if the driving 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 driving frequency of the timer control valve M8 changes as the engine speed changes. Immediately after the duty ratio command value is changed, the duty ratio command value does not change too much. Therefore, the deviation in the timing of fuel injection from the fuel injection pump M1 is not exacerbated, and the timing of fuel injection does not change suddenly.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the fuel injection timing control device for a diesel engine according to the present invention is applied to an automobile will be described in detail below 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 thereof. The fuel injection pump 1 includes a drive pulley 3 that is drivingly connected to a crankshaft 40 of a 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 fuel is force-fed to each fuel injection nozzle 4 provided for each cylinder (four cylinders in this case) of the diesel engine 2, thereby injecting the fuel. .

In the fuel injection pump 1, a drive pulley 3 is attached to the tip of a drive shaft 5. Further, a fuel feed pump 6 (expanded at 90 degrees in this figure), which is a vane type pump, is provided in the middle of the drive shaft 5. Further, a disk-shaped pulser 7 is attached to the base end side of the drive shaft 5. On the outer peripheral surface of this pulser 7, there is a diesel engine 2
The same number of incisors as the number of cylinders, that is, four in this case, are formed at equal angular intervals, and 14 protrusions (56 in total) are formed at equal angular intervals between each incisor. There is. A base end portion of the drive shaft 5 is connected to a cam plate 8 via a coupling (not shown).

A roller ring 9 is provided between the pulser 7 and the cam plate 8, and a plurality of cam rollers 10 are mounted along the circumference of the roller ring 9 to face the cam face 8a of the cam plate 8. There is. cam face 8
The number a is the same as the number of cylinders of the diesel engine 2. Further, the cam plate 8 is always urged into engagement with the cam roller 10 by a spring 11.

The base end of a fuel pressurizing plunger 12 is attached to the cam plate 8 so as to be able to rotate together with 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 engages with the cam roller 10 while rotating, and reciprocates in the left and right directions in the figure by the same number of cylinders. Driven. Further, along with this reciprocating movement, the plunger 12 is rotated and reciprocated in the same direction. In other words,
The plunger 12 is moved forward (lifted) in the process where 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 in the process where the cam face 8a rides down on the cam roller 10.

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

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 through 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
6 communicates with the suction port 19, 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 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 is injected.

A spill passage 22 is formed in the pump housing 13 for communicating fuel overflow (spill) between the high pressure chamber 15 and the fuel chamber 21 . An electromagnetic spill valve 23 serving as a spill adjustment valve for adjusting fuel spill from the high pressure chamber 15 is provided in the middle of the spill passage 22 . This electromagnetic spill valve 23 is a normally open type valve, and when the coil 24 is not energized (off), the valve body 25 is opened and the fuel in the high pressure chamber 15 is spilled into the fuel chamber 21 . Further, when the coil 24 is energized (turned on), the valve body 25 is closed and spilling of fuel from the high pressure chamber 15 to the fuel chamber 21 is stopped.

Therefore, by controlling the energization 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 controlled. Then, by opening the electromagnetic spill valve 23 during the compression stroke of the plunger 12, the pressure of the fuel in the high pressure chamber 15 is reduced, and fuel injection from the fuel injection nozzle 4 is stopped. That is, even if 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 fuel injection from the fuel injection nozzle 4 is not performed. Further, while the plunger 12 is moving forward, the amount of fuel injected from the fuel injection nozzle 4 is controlled by controlling the timing of closing and opening of the electromagnetic spill valve 23.

A timer device 26 (expanded 90 degrees in this figure) is provided on the lower side of the pump housing 13 for adjusting the fuel injection timing. This timer device 26 changes the timing at which the cam face 8a engages with the cam roller 10, that is, the timing at which the cam plate 8 and the plunger 12 are driven back and forth by changing the position of the roller ring 9 with respect to the rotational direction of the drive shaft 5. It is for.

This timer device 26 is hydraulically driven, and includes a timer housing 27, a timer piston 28 fitted in the housing 27, and a low pressure chamber 29 on one side of the timer housing 27. It is composed of a timer spring 31 and the like that presses the piston 28 toward the pressurizing chamber 30 on the other side. The timer piston 28 is connected to the roller ring 9 via a slide pin 32.

The pressurizing chamber 30 of the timer housing 27 includes:
Pressurized fuel is introduced by a fuel feed pump 6. The position of the timer piston 28 is determined by the balance between the fuel pressure and the biasing force of the timer spring 31. Furthermore, by determining the position of the timer piston 28, the position of the roller ring 9 is determined, and the plunger 1 is moved through the cam plate 8.
2 reciprocating timing is determined.

In order to adjust the fuel pressure of the timer device 26, that is, the control oil pressure, the timer device 26 includes a timer control valve (
TCV) 33 is provided. That is, the pressurizing chamber 30 and the low pressure chamber 29 of the timer housing 27 are communicated with each other by a communication passage 34, and the TCV 33 is provided in the middle of the communication passage 34. The TCV 33 is an electromagnetic valve whose opening and closing are controlled by a duty-controlled energization signal, and the fuel pressure within the pressurizing chamber 30 is adjusted by opening and closing the TCV 33 . By adjusting the fuel pressure, the lift timing of the plunger 12 is controlled, and the timing of fuel injection from each fuel injection nozzle 4 is adjusted.

A rotation speed sensor 35 made of an electromagnetic pickup coil is attached to the upper part of the roller ring 9 so as to face the outer peripheral surface of the pulser 7. This rotation speed sensor 35
detects the passage of protrusions and the like of the pulser 7 and outputs a timing signal (engine rotation pulse) corresponding to the engine rotation speed NE. Furthermore, since the rotation speed sensor 35 is integrated with the roller ring 9, it 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 explained. In this diesel engine 2, a main combustion chamber 44 corresponding to each cylinder is formed by a cylinder 41, a piston 42, and a cylinder head 43, respectively. or,
Each of the main combustion chambers 44 is connected to a sub-combustion chamber 45 corresponding to each cylinder. Then, 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 starting aid 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 copresor 49 of a turbocharger 48 constituting a supercharger, and the exhaust pipe 50 is provided with a turbocharger 49. 48
A turbine 51 is provided. Further, the exhaust pipe 50 is provided with a waste gate valve 52 that adjusts the supercharging pressure PiM.
is provided. As is well known, this turbocharger 48 utilizes the energy of exhaust gas to power the turbine 5.
1 is rotated, and a compressor 49 on the same axis is rotated to increase the pressure of intake air. This allows a high-density air-fuel mixture to be sent into the main combustion chamber 44 to combust a large amount of fuel, thereby increasing the output of the diesel engine 2.

The diesel engine 2 also has an exhaust pipe 5.
A recirculation pipe 54 is provided for recirculating a part of the exhaust gas in the exhaust gas into the intake port 53 of the intake pipe 47. An exhaust gas recirculation valve (EGR valve) 55 is provided in the middle of the recirculation pipe 54 to adjust the amount of recirculation of exhaust gas. This EGR valve 55 is controlled to open and close by controlling a vacuum switching valve (VSV) 56.

Furthermore, a throttle valve 58 is provided in the middle of the intake pipe 47 and is opened and closed in conjunction with the amount of depression of the accelerator pedal 57. Also, the throttle valve 5
A bypass passage 59 is provided in parallel to 8, and a bypass throttle valve 60 is provided in the bypass passage 59. This bypass throttle valve 60 is controlled to open and close by an actuator 63 having a two-stage diaphragm chamber driven by the control of two VSVs 61 and 62. This bypass throttle valve 60 is controlled to open and close depending on various operating conditions. For example, during idling operation, it is controlled to a half-open state to reduce noise and vibration, etc., during normal operation, it is controlled to a fully open state, and when the operation is stopped, it is controlled to a fully closed state to ensure a smooth stop.

[0030] As described above, the electromagnetic spill valve 23 provided in the fuel injection pump 1 and the diesel engine 2
, TCV33, glow plug 46 and each VSV56,6
1 and 62 are electrically connected to an electronic control unit (hereinafter simply referred to as "ECU") 71 that constitutes injection amount control means, injection timing control means, drive frequency change means, and duty ratio correction means, and are controlled by the ECU 71. Their drive timings are controlled.

In addition to the rotational speed sensor 35, the following various sensors are provided as sensors constituting the operating state detection means. That is, an intake air temperature sensor 7 is installed in the intake pipe 47 to detect the intake air temperature THA near the air cleaner 64.
2 is provided. Further, an accelerator opening sensor 73 is provided that detects an accelerator opening ACCP corresponding to the load of the diesel engine 2 from the opening/closing position of the throttle valve 58. An intake pressure sensor 74 is provided near the intake port 53 to detect the intake air pressure after being supercharged by the turbocharger 48, that is, the supercharging pressure PiM. Furthermore, the cooling water temperature THW of diesel engine 2
A water temperature sensor 75 is provided to detect the water temperature. Further, a crank angle sensor 76 is provided that detects the rotational position of the crankshaft 40 of the diesel engine 2 with respect to a rotational reference position, for example, the top dead center of a specific cylinder. Furthermore, in the transmission (not shown), a reed switch 77b is turned on and off by a magnet 77a which is rotated by the rotation of the gear, and the vehicle speed (vehicle speed) S is controlled.
A vehicle speed sensor 77 for detecting P is provided.

The above-mentioned sensors 72 to 77 are connected to the ECU 71, and the rotation speed sensor 3 is also connected to the ECU 71.
5 is connected. In addition, the ECU 71 has each sensor 35,
Based on the signals output from 72 to 77, the electromagnetic spill valve 23, TCV 33, glow plug 46 and VSV 56
, 61, 62, etc. are suitably controlled. Next, the EC mentioned above
The configuration of U71 will be explained according to the block diagram of FIG. The ECU 71 includes a central processing unit (CPU) 81, a read-only memory (ROM) 82 that stores predetermined control programs and maps, etc., a random access memory (RAM) 83 that temporarily stores calculation results of the CPU 81, etc.
Backup RAM 8 to save pre-stored data
4 etc., each of these parts, input port 85 and output port 8
6 and the like are connected by a bus 87 as a logic operation circuit.

The input port 85 has the aforementioned intake temperature sensor 72, accelerator opening sensor 73, intake pressure sensor 74, and water temperature sensor 75 connected to each buffer 88, 89, 90, 9.
1, connected via a multiplexer 93 and an A/D converter 94. Similarly, the aforementioned rotation speed sensor 35, crank angle sensor 76, and vehicle speed sensor 77 are connected to the input port 85 via a waveform shaping circuit 95. Then, the CPU 81 reads detection signals from the sensors 35, 72 to 77, etc. inputted through the input port 85 as input values. Further, each drive circuit 96 is connected to the output port 86.
, 97, 98, 99, 100, 101 to the electromagnetic spill valve 23, TCV 33, glow plug 46 and VSV 5.
6, 61, 62, etc. are connected.

[0034]The CPU 81 then controls each sensor 35, 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 ECU7 mentioned above
The processing operation of the fuel injection timing control executed in step 1 will be described with reference to the flowcharts shown in FIGS. 5, 8, and 9, and the time charts shown in FIGS. 6 and 7.

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

When the process shifts to this routine, first, in step 101, the engine rotation speed NE is read based on the detected value of the rotation speed sensor 35. Subsequently, in step 102, based on the engine rotation pulse obtained from the detected value of the rotation speed sensor 35, the interrupt pulse counter CNIRQ of the engine rotation speed NE is added by "1" to the spill reference pulse number CANGL corresponding to the injection end time. It is determined whether the specified number of pulses has been reached. In other words, it is determined whether or not fuel injection has completely ended. For example, Figure 6
As shown in , the spill reference pulse number CANGL is "4".
In this case, the value of the interrupt pulse counter CNIRQ at which the fuel injection completely ends is "5".

[0037] If the fuel injection is not completely completed, the subsequent processing is temporarily terminated. On the other hand, if the fuel injection has completely ended, the process moves to the next step 103. Then, in step 103, it is determined whether an on/off switching counter CTCV for instructing on/off switching of the TCV 33 is "0". This on/off switching counter CTCV is set in step 106, which will be described later, in accordance with the magnitude of the engine rotational speed NE.

Here, the on/off switching counter CTCV
If not "0", in step 104, the result of subtracting "1" from the value of the on-off switching counter CTCV is set as the new value of the on-off switching counter CTCV, and the subsequent processing is temporarily terminated. do. Also, in step 103, the on/off switching counter CTCV
If 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, in step 106, the value of the above-mentioned on/off switching counter CTCV is set in accordance with the magnitude of the engine rotational speed NE. That is, if the engine speed NE at that time is less than "1200 rpm", the value of the on/off switching counter CTCV is set to "1", and if the engine speed NE is "1200 rpm" or more but less than "2400 rpm", In this case, the value of the on/off switching counter CTCV is set to "2", and if 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
When is set to "1", for example, as shown in FIG. 7, the on-time TON is set every time one fuel injection is completed and the "CANGL+1"th engine rotation pulse is input and starts. . In addition, when the on/off switching counter CTCV is set to "2", the fuel injection ends twice and the on time TON changes every time the "CANGL+1" engine rotation pulse immediately after is input and starts. Set. Furthermore, when the on/off switching counter CTCV is set to "4", the fuel injection is completed four times, and the on time T is changed every time the "CANGL+1" engine rotation pulse immediately after that is input and starts.
ON is set.

In other words, by opening the TCV 33 during the non-injection period after the end of fuel injection, a shift in the spill timing due to the driving reaction force of the roller ring 9 is prevented. When the engine is being driven, the driving frequency of the TCV 33 increases as the engine speed NE increases, so the driving frequency of the TCV 33 increases too much when the engine rotates at high speeds, which is unfavorable in terms of reliability. Therefore,
By changing the valve opening of TCV33 after the completion of the second fuel injection and even after the completion of the fourth fuel injection in accordance with the increase in the engine speed NE, the drive frequency is further changed to maintain the drive frequency within an appropriate range. . In this example, TCV33
In the case of a 4-cylinder 4-cycle engine, the driving frequency of the on/off switching counter CTCV changes from "1" to "2" or from "2" to "1" depending on the magnitude of the engine speed NE.
, and further from "2" to "4" or from "4" to "2", respectively from "40Hz" to "20H".
z” or “20Hz” to “40Hz”.

Next, in step 107, TCV3
On-duty time FS for duty control of 3
When calculating DUTY, a rotational speed correction term KSY used as a correction term based on the engine rotational speed NE is calculated. This rotation speed correction term KSY is calculated according to the following formula. KSY=(NE÷CTCV-600)÷600×
0.15+0.85, that is, this rotation speed correction term KSY is:
The set value of the on/off drive counter CTCV in step 106 is changed due to a change in the engine speed NE, and the timer device 26 sets the same actual injection timing according to the engine speed NE when the drive frequency of the TCV 33 is changed. It means the correction value to which the duty ratio command value of the TCV 33, which will be described later, is corrected in order to maintain the value. Also, the value of this rotational speed correction term KSY is, for example, when the engine rotational speed NE reaches "1200 rpm" and TC
After the drive frequency of the V33 is changed from "40Hz" to "20Hz", it changes linearly until it increases again to "40Hz" as the engine speed NE increases. Furthermore, in the formula for calculating the rotational speed correction term KSY, the constant term "0.85" changes when the driving frequency of the TCV 33 is switched from "40Hz" to "20Hz".
This indicates that in order to maintain the timer piston 28 of the timer device 26 at the same position, that is, to maintain the timer position, the on-duty time FSDUTY may be corrected to "85%". Furthermore, this constant “0.85
” is a value determined in advance through experiments, and is determined depending on the difference in the characteristics of the hydraulic path related to the timer device 26.

Furthermore, in step 108, TCV3
3, an on-duty time FSDUTY as shown in FIG. 7 is calculated. This on-duty time FSDUTY is based on the target on-duty ratio FTDUTY, which is separately obtained as a base value, and the crank angle conversion time T180 for each 180 degrees, which is separately obtained.
It is determined by multiplying the previously set value of the on/off switching counter CTCV by the previously determined rotational speed correction term KSY. And its on-duty time FSDU
Once the calculation of TY is completed, the subsequent processing is temporarily ended.

At step 108, the target on-duty ratio FTDUTY used to calculate the on-duty time FSDUTY is determined according to the flowchart shown in FIG. This flowchart is for ECU7
1, and is executed by a regular interrupt every 50 ms. That is, first step 201
In step , the engine rotation speed NE is read based on the detected value of the rotation speed sensor 35, and the final injection amount QFIN is read as a command value of the target injection amount, which is separately determined. Next, in step 202, based on the read engine speed NE and final injection amount QFIN,
A target crank angle timing TRGCA as a command value for the target injection timing is calculated with reference to a predetermined map (not shown).

Next, in step 203, the obtained target crank angular timing TRGCA is read, and the separately obtained actual crank angular timing ACTCA as the injection timing detection value is read. And step 204
, the read actual crank angle timing ACTC
Based on the difference between A 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 way is based on the same target crank angle timing TRGC.
This is a value that constitutes a duty ratio command value for A. Then, for the target on-duty ratio FTDUTY,
In step 108 of the flowchart shown in , the crank angle conversion time T180, the on/off switching counter CT
By multiplying the value of CV and the rotation speed correction term KSY, the on-duty time FSDUTY, which takes into account the change in the drive frequency of the TCV 33, is calculated.

On the other hand, as shown in FIG. 7, setting of the off time TOFF for turning off the TCV 33 is performed according to the flowchart shown in FIG. This flowchart is a processing routine executed by the ECU 71, and T
This is executed with an interrupt every time the ON time TON of CV33 is set. That is, first in step 301, the current time TN is read. Subsequently, in step 302, the above-mentioned on-duty time F is set at the current time TN.
The result of adding SDUTY is set as the off time TOFF, and when the off time TOFF arrives, the TCV 33 is turned off and closed.

According to the above-described processing, the on-time TO of the TCV 33 is determined according to the engine speed NE at the time.
N and off time TOFF are set, respectively, and TCV3
3 is duty controlled. Therefore, in the diesel engine fuel injection timing control device 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. Then, the driving frequency of TCV33 is “2”.
After the frequency is changed to "0 Hz" and until it increases again to "40 Hz" as the engine speed NE increases, the ON Duty time FSDUTY is TCV3
It is corrected according to the change in the drive frequency of No. 3 and, in turn, the change in the engine rotation speed NE. In other words, during the period from when the driving frequency of the TCV 33 is changed to "20Hz" until it rises to "40Hz" again, the on-duty time FSDUTY
is changed linearly 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 timer device 26 is used to maintain the same fuel injection timing, the higher the driving frequency of the TCV 33, the more difficult it is for the oil pressure to escape, and the on-duty time FSDUTY must be increased. There is a need to. On the other hand, the lower the drive frequency is, the more easily the oil pressure is released, and it is necessary to reduce the on-duty time FSDUTY. However, in this embodiment, as described above, the duty ratio command value of the TCV 33 is gradually changed linearly during the change of the drive frequency, so that a delay in response due to oil pressure leakage 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 maintained at a constant position, and the fuel injection timing can be prevented from being retarded. In other words, it is possible to prevent the actual fuel injection timing from being temporarily delayed immediately after the driving frequency of the TCV 33 is changed from "40 Hz" to "20 Hz".

Conversely, the engine speed NE decreases and the driving frequency of the TCV 33 changes from "20Hz" to "40Hz".
Hz" and then decreases to "20 Hz" again, the on-duty time FSDUTY of the TCV 33 is linearly changed without becoming too small. Therefore,
The duty ratio command value of the TCV 33 is gradually changed linearly, and the responsiveness of the hydraulic pressure released from the pressurizing chamber 30 of the timer device 26 can be improved. As a result, the timer position can be suitably maintained at a constant position,
It is possible to prevent the fuel injection timing from advancing. In other words, the drive frequency of TCV33 changes from "20Hz" to "
It is possible to prevent the actual fuel injection timing from being temporarily advanced immediately after the frequency is changed to 40Hz.

Therefore, when the driving frequency of the TCV 33 is changed, sudden changes in the fuel injection timing and fuel injection period can be suppressed and stabilized. Therefore, in this embodiment, when changing the driving frequency of the TCV 33, the timing of fuel injection from the fuel injection pump 1 can be stabilized, so that the injection timing is not advanced any further. As a result, generation of unnecessary torque due to advance angle is eliminated, and generation of unnecessary vibration in the diesel engine 2 can be prevented.

Furthermore, in the diesel engine 2, it is also possible to prevent knocking noise caused by advancing the fuel injection timing. Furthermore, it is possible to prevent an unnecessary increase in combustion temperature due to the advance of the fuel injection timing, thereby also preventing deterioration of exhaust emissions. In addition, T
Since there is no need to retard the fuel injection timing due to a change in the driving frequency of the CV 33, it is possible to prevent the combustion temperature from decreasing unnecessarily, thereby preventing misfires from occurring.

It should be noted that the present invention is not limited to the above-mentioned embodiments, but may be implemented as follows by appropriately changing a part of the structure without departing from the spirit of the invention. (1) In the embodiment described above, the electromagnetic spill valve 23 was used as the spill adjustment valve, but a piezo spill valve using a piezo element may also be used. (2) In the above embodiment, the diesel engine 2 is equipped with the turbocharger 48 as a supercharger, but
It can also be embodied in a diesel engine equipped with a supercharger as a supercharger or a diesel engine without a supercharger.

[0054]

As described in detail above, according to the present invention, in a fuel injection pump, fuel is pressurized in a high pressure chamber by a plunger that is reciprocated in conjunction with the rotation of a diesel engine, and the spill regulating valve is The fuel injection amount is adjusted by adjusting the fuel spill from the high pressure chamber and the end timing of fuel pressurization, and the hydraulic timer is driven by the duty-controlled timer control valve to reciprocate the plunger. The fuel injection timing is adjusted by changing the timing, and in addition, the drive frequency of the timer control valve is changed in response to changes in engine speed, so that the timer is changed in response to changes in engine speed. Since 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 duty ratio command values can be avoided when the drive frequency of the timer control valve is changed. This has the excellent effect of suppressing sudden changes in fuel injection timing and injection period and stabilizing them.

[Brief explanation of the drawing]

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 in an embodiment embodying 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 the configuration of an ECU in one embodiment.

FIG. 5 shows a TC executed by an ECU in one embodiment.
3 is a flowchart illustrating a processing routine executed by an interrupt every time an engine rotation pulse is input to calculate the on-duty time of V. FIG.

FIG. 6 is a time chart illustrating the correspondence among engine rotation pulses, opening/closing of an electromagnetic spill valve, and plunger lift in one embodiment.

[Fig. 7] Engine rotation pulse and TCV in one embodiment
It is a time chart explaining the correspondence of on-off driving.

FIG. 8 shows a TC executed by an ECU in one embodiment.
FIG. 2 is a flowchart illustrating a processing routine executed by a regular interrupt every 50 ms to calculate a target on-duty time of V. FIG.

FIG. 9 shows a TC executed by an ECU in one embodiment.
12 is a flowchart illustrating a processing routine executed by an interrupt every time a TCV is set for an on-time to set a V-off time.

[Explanation 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 a spill adjustment valve, 26... Timer device, 33... Timer control valve (TCV),
35...Rotation speed sensor constituting the operating state detection means, 71
...ECU that constitutes injection amount control means, injection timing control means, drive frequency changing means, and duty ratio correction means.

Claims (1)

[Claims] 1. A plunger provided in a fuel injection pump, driven reciprocally via a cam in conjunction with the rotation of a diesel engine, and pressurizing fuel in a high pressure chamber for fuel injection; a spill adjustment valve that is driven to open and close to adjust the fuel spill from the high pressure chamber in order to adjust the end timing of fuel pressurization in the high pressure chamber; a timer driven by hydraulic pressure to change the reciprocating drive timing of the plunger via the cam in order to adjust the fuel injection timing; and a timer control valve whose duty is controlled to adjust the control hydraulic pressure in the timer. , an operating state detecting means for detecting the operating state including the rotational speed of the diesel engine, and driving and controlling the spill regulating valve to obtain a required target injection amount determined based on the detection result of the operating state detecting means. In order to obtain a required target injection timing determined based on the detection results of the injection amount control means and the operation state detection means, an injection timing control means for controlling the duty of the timer control valve, and an injection timing control means that is detected by the operation state detection means. A fuel injection timing control device for a diesel engine, comprising: drive frequency changing means for changing the drive frequency of the timer control valve in response to changes in engine rotational speed;
The present invention is characterized in that a duty ratio correction means is provided for correcting a duty ratio command value for the same target injection timing in the injection timing control means in accordance with the drive frequency of the timer control valve changed by the drive frequency change means. Diesel engine fuel injection timing control device.