JPH09144567A - Fuel injection control device for diesel engine - Google Patents

Abstract

(57) 【Abstract】 PROBLEM TO BE SOLVED: To make an actual injection period coincide with a target injection period, and according to a difference between the injection periods, an initial lift amount of a nozzle for multi-stage injection and an oil feed rate control type oil feed pump Correcting the rate eliminates the possibility of increasing NOx and smoke emissions. A jerk-type fuel injection pump that pumps fuel by a plunger is provided. In this case, the nozzle 11
In No. 2, the needle lifts in stages according to the pressure of the fuel to be pumped, and the fuel is injected in multiple stages. The adjusting unit 112 can adjust the initial lift amount of the nozzle 112 according to the control amount. The detecting unit 114 detects the actual injection period, compares the actual injection period with the target injection period, and the determining unit 115 determines the control amount to the initial lift amount adjusting unit 112 so that they match.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection control device for a diesel engine, which improves exhaust emission characteristics by low temperature premix combustion.

[0002]

2. Description of the Related Art NOx can be reduced by conducting a so-called exhaust gas recirculation (EGR) to guide a part of exhaust gas to an intake pipe and slowly burning it. Therefore, the EGR rate is increased as the load becomes lower. However, under conditions of high EGR rate, smoke (mainly black smoke) emission increases, so swirl generation means for generating swirl (swirl vortex) in the combustion chamber by intake air is provided, and air and fuel during diffusion combustion are In addition to improving the mixing of the fuel, the fuel injection timing is delayed until after top dead center, the temperature in the combustion chamber at the ignition timing is kept low, and the premix combustion ratio is increased.
A device has been proposed that suppresses the generation of smoke in the R rate state as much as possible (see Japanese Patent Laid-Open No. 7-4287).

[0003]

By the way, in such a device, the injection period is determined in consideration of the EGR amount, the swirl ratio, and the injection timing so that NOx and smoke are optimally reduced. However, the actual injection period may be prolonged or too short due to variations and deterioration with the manufacture and assembly of the fuel injection nozzle, and when the deviation of this injection period occurs especially in the high EGR rate state,
The amount of NOx and smoke emitted may increase.

Therefore, in the present invention, when the actual injection period is deviated from the target injection period, the initial lift amount of the nozzles for multi-stage injection and the actual injection period are matched with the target injection period in accordance with the difference in the injection periods. An object of the present invention is to eliminate the risk that NOx and smoke emissions will increase by correcting the oil feed rate of the oil feed rate control type fuel injection pump.

[0005]

According to the first invention, FIG.
In a fuel injection control device for a diesel engine equipped with a jerk type fuel injection pump that pressure-feeds fuel by a plunger, a nozzle that multistage-injects fuel by lifting needles stepwise according to the pressure of the pressure-feed fuel. Means 112 that can adjust the initial lift amount of 112 according to the control amount, Means 113 that calculates the target injection period based on the engine speed and load, Means 114 that detects the actual injection period, and this actual injection Means 115 is provided for comparing the period and the target injection period and determining the control amount for the initial lift amount adjusting unit 112 so that they match.

According to a second aspect of the present invention, in the first aspect of the present invention, the control amount determining means 115 calculates the basic initial lift amount according to an operating condition, and determines the difference between the actual injection period and the target injection period. It comprises means for calculating an initial lift correction amount and means for determining a value obtained by correcting the basic initial lift amount by the initial lift correction amount as the control amount.

According to a third aspect of the present invention, as shown in FIG. 28, in a fuel injection control device for a diesel engine equipped with a fuel injection pump that pumps fuel by a plunger, the cam phase of the fuel injection pump is controlled according to the control amount. Adjustable means 121, means 113 for calculating the target injection period based on the engine speed and load, means 114 for detecting the actual injection period, and comparison between the actual injection period and the target injection period, Means 122 for deciding the control amount to the cam phase adjusting means 121 is provided so that they coincide with each other.

In a fourth aspect based on the third aspect, the control amount determining means 122 determines the basic cam phase according to an operating condition and the difference between the actual injection period and the target injection period. It comprises means for calculating a cam phase correction amount and means for determining a value obtained by correcting the basic cam phase with the cam phase correction amount as the control amount.

According to a fifth aspect of the invention, in the third or fourth aspect of the invention, as shown in FIG. 29, means 131 for adjusting the prestroke amount of the fuel injection pump according to the control amount.
And the actual injection period and the target injection period are compared, and the prestroke amount adjusting means 13 is adjusted so that they match each other.
Means 132 for determining the controlled variable to 1.

In a sixth aspect based on the fifth aspect, the control amount determining means 132 calculates a basic prestroke amount according to an operating condition and a difference between the actual injection period and the target injection period. Accordingly, it comprises means for calculating a prestroke amount correction amount and means for determining a value obtained by correcting the basic prestroke amount by the prestroke amount correction amount as the control amount.

According to a seventh invention, in any one of the first to sixth inventions, means for adjusting the exhaust gas recirculation rate, means for adjusting the swirl ratio, and fuel injection timing can be adjusted. Means, the swirl ratio becomes larger as the exhaust gas recirculation ratio becomes higher and the rotational speed becomes lower in the full load region of the medium speed / medium load range and the low speed, and the fuel injection timing is compressed at a higher exhaust gas recirculation ratio. The above 3 so as to be delayed until the dead point
And means for determining each controlled variable to the one adjusting means.

[0012]

In the nozzle in which the needle is lifted in stages to inject fuel in multiple stages, a small amount of fuel is injected during the initial lift period and a large amount of fuel is injected during the subsequent lift period. In this case, in the first aspect of the present invention, when the actual injection period is longer than the target injection period, the initial lift amount is increased, so the injection rate characteristic changes and the injection period is shortened. It is possible to match the period with the target injection period. On the contrary, when the actual injection period is shorter than the target injection period, the initial lift amount is reduced to increase the injection period, and the actual injection period coincides with the target injection period.
In this way, by determining the initial lift amount of the nozzle so that the actual injection period matches the target injection period, the emission amount of NOx and smoke accompanying the deviation of the injection period particularly in the high EGR rate state The increase can be prevented.

According to the cam phase adjusting means, when the cam phase is advanced, the oil feed rate is increased and the injection period is shortened. Conversely, when the cam phase is retarded, the oil feed rate is decreased and The injection period becomes longer. In this case, in the third aspect of the invention, when the actual injection period is longer than the target injection period, the cam phase is advanced, so that the injection period is shortened, whereby the actual injection period and the target injection period are reduced. Can be matched. On the contrary, when the actual injection period is shorter than the target injection period, the cam phase is retarded to increase the injection period, and the actual injection period coincides with the target injection period. In this way, by determining the cam phase so that the actual injection period matches the target injection period, it is possible to prevent an increase in the emission amount of NOx and smoke caused by the deviation of the injection period particularly in the high EGR rate state. it can.

However, in the third or fourth invention,
When the pre-stroke amount is increased, the injection amount remains constant, the injection timing is retarded, and when the fuel injection pump has the characteristic that the oil feed rate increases, the actual injection period is set to the target injection period. In order to make them coincide with each other, for example, when the cam phase is advanced to increase the oil feed rate, the injection timing is retarded at the same time, and when the cam phase is retarded to decrease the oil feed rate, the injection is performed simultaneously. Although the timing advances, in the fifth aspect of the invention, when the actual injection period is longer than the target injection period, the prestroke amount is reduced to advance the injection timing, and when the actual injection period is shorter than the target injection period. To increase the prestroke amount and delay the injection timing,
Even when the oil feed rate is corrected so that the actual injection period and the target injection period match, the injection timing does not change.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1, reference numeral 1 denotes a distribution type fuel injection pump in which the fuel injection timing and the fuel injection amount are electronically controlled. The fuel pumped from the fuel injection pump 1 is guided to the injection nozzle 3 through the pipe 2.

Reference numeral 4 is an intake passage, 5 is an exhaust passage, 6 is a filter for collecting particulates in the exhaust, and 7 is an exhaust muffler for reducing exhaust noise.

Reference numeral 8 is an EGR passage for communicating the exhaust passage 4 and intake passage 5 to recirculate the exhaust gas, and 9 is a diaphragm type E for controlling the EGR amount (exhaust gas recirculation amount) in response to the control negative pressure.
It is a GR valve.

Reference numeral 10 denotes a negative pressure control valve which is supplied to the EGR valve 9 and which adjusts a constant negative pressure from the vacuum pump 12 in three stages according to a duty signal from the control unit 11. For example, when the OFF duty to the negative pressure control valve 10 (OFF time ratio of a constant cycle) is the maximum value and a constant negative pressure is directly introduced to the EGR valve 9, 50% of the exhaust gas is set to be recirculated. To do. EGR at this time
The rate (= EGR amount / fresh air amount) corresponds to 100%. OF
When the F duty is reduced stepwise, the negative pressure control valve 10
Due to the decrease in the control negative pressure to, the EGR valve opening is gradually reduced and the EGR rate is reduced to 60% and 30%.

The three-stage EGR rate thus obtained is set as shown in FIG. 2 with respect to operating conditions. In the figure, the EGR rate is 100 in the medium-speed / medium-load range and the low-speed full-load range.
%. In a high-speed high-load region contrast, can not be completely suppressed the generation of smoke and prolonged combustion period, further the intake air temperature rises in increase in the exhaust temperature and an increase of the EGR flow rate, NO _x reduction by EGR EGR rate is 60%, 30%
And gradually decreasing.

A control unit 1 comprising a microcomputer for controlling the EGR rate according to the operating conditions of the engine.
1, a control unit 11 includes a sensor for detecting an accelerator opening (accelerator pedal opening), a signal from an air flow meter 14 for detecting an intake air amount Q taken into the intake passage 5 via an air cleaner 13, The EGR flow rate is controlled stepwise based on the reference pulse and scale pulse related to the rotation speed signal.

A map having accelerator opening Acc and engine speed Ne as parameters so that the characteristics of the EGR rate (target EGR rate) shown in FIG. 2 with respect to the torque generated by the engine and the engine speed can be obtained. (Not shown) is set, this map is searched, and the target EG at that time is searched.
Calculate the R rate. This and the air flow meter flow rate (new air amount)
From this, the EGR flow rate is calculated by EGR flow rate = air flow meter flow rate × target EGR rate, and the OFF duty to the negative pressure control valve 10 is determined so that the EGR gas of this flow rate flows.

Means for producing swirl in the intake air flowing into the combustion chamber are shown in FIGS. 3 and 4 (but not shown in FIG. 1). A rotary blade 22 that is rotatably provided near a spiral passage 21b of a so-called helical intake port 21 (formed by a substantially straight intake passage 21a and a spiral passage 21b around the intake valve axis). A link mechanism (not shown) connected to the blade 22 and an actuator (not shown) for driving the link mechanism, and the swirl ratio can be adjusted by the rotational position of the blade 22.

For example, the blade 22 has a high swirl ratio at the position shown in FIG. 3, but has a low swirl ratio when the blade 22 reaches the position shown in FIG. This rotating blade system has a quick response and can control a wide swirl ratio. Therefore, it is suitable for controlling the HC that reacts sensitively to the swirl ratio.

FIG. 5 shows the characteristics of swirl ratio with respect to operating conditions.
As shown in, the swirl ratio is increased in the lower engine speed range. On the other hand, in the high engine speed range, the decrease in volume (intake air charging) efficiency due to the high swirl ratio becomes noticeable, and the improvement in combustion by increasing the injection pressure weakens the need for swirl. The swirl ratio is gradually reduced as is increased.

The actuator for the variable swirl is a diaphragm type actuator with a two-stage spring (not shown), and this actuator dilutes the atmosphere to a constant negative pressure from a negative pressure source to control the negative pressure in three stages. It is composed of a negative pressure control valve.

Next, FIG. 6 shows an outline of the distribution type fuel injection pump 1. In FIG. 6, the fuel injection pump 1 includes a plunger 33 that compresses the fuel in the pressurizing chamber 32 while rotating and reciprocating while engaging with a cam roller in an injection pump body 31 that forms a pump housing. This plunger 33
A control sleeve 35 that adjusts the fuel injection amount by opening and closing a cutoff port 34 formed in the plunger 33 is slidably fitted around the outer periphery of the rotary solenoid 36 that drives the control sleeve 35. It is provided.

The fuel discharged from the feed pump 37 attached to the pump drive shaft lubricates the inside of the pump and accumulates pressure in the pump chamber 38, from which it is sucked into the pressurizing chamber 32.

In order to control the fuel injection timing, a timer piston 39 is provided as an injection timing control member that moves the phase of the cam roller while engaging with the cam roller that drives the plunger 33. The position of the timer piston 39 is controlled by a timing control valve 40 (see FIG. 7) that controls the flow rate of fuel leaked from the high pressure chamber at one end to the low pressure chamber side, thereby advancing or delaying the fuel injection timing. I will horn.

A control unit 11 is provided to control the fuel injection amount, injection timing, and the like. The control unit 11 is provided with various sensors constituting the operation state detecting means, that is, the positions of the nozzle lift sensor 15 and the control sleeve 35, which are mounted on the fuel injection nozzle 3 and actually measure the injection timing, as the actual injection timing detecting means. A sleeve position sensor 16 that detects the fuel injection amount (representative value of the load), a water temperature sensor 17 that detects the cooling water temperature, a rotation speed sensor 18 that detects the engine speed,
Signals from various sensors such as a fuel temperature sensor 19 that detects the fuel temperature and a start switch 20 that recognizes an engine start command are input, and the fuel injection amount and injection timing are controlled based on these signals, as will be described later.

The characteristics of the injection timing with respect to the operating conditions are shown in FIG. 8. The injection timing is after top dead center (+ 4ATDC and + 2ATDC) in the medium and high load range in the low revolution range where the EGR rate is high.
I have to. This is to suppress the generation of smoke by making intake air cooler by significantly delaying the injection timing and increasing the premixed combustion ratio.
On the other hand, in the middle-high rotation range, even if the ignition delay time is constant, the ignition delay crank angle becomes large. Therefore, in order to keep the ignition timing constant, the injection timing is advanced as the rotational speed increases.

FIG. 9 is a control block diagram of the injection timing control.
In S21, the fuel injection timing Tnl is determined based on the rotation-load characteristic of the injection timing set by the engine speed Ne and the load (represented by the fuel injection amount and the accelerator opening degree) during the normal operation. This rotation-load characteristic of the injection timing is a map set so that the characteristics of the fuel injection timing shown in FIG. 8 can be obtained with respect to the torque generated by the engine and the engine speed.

In step S22, the fuel injection timing ITst is determined based on the start injection timing advance characteristic set by the engine speed Ne and the water temperature Tw when the engine is started.

Then, in S23, the target injection timing I
Tt is compared with the measured injection timing ITi measured by the nozzle lift sensor 15, the movement amount of the timer piston 39 is obtained by PID processing, and the actuator command signal (duty ratio of the timing control valve 40, etc.) is output, This controls the fuel injection timing.

FIG. 10 shows a sectional view of the fuel injection nozzle 3. The injection nozzle 3 has two stages of low and high injection start pressures, and includes two injection start pressure adjusting means.

The first adjusting means as the adjusting means of the injection starting pressure of the initial injection is the start of injection of the nozzle 51, the injection amount,
It is arranged above the needle 52 that regulates the end,
An upper inner hole 54 provided on the opposite side of the nozzle 51 of the nozzle holder 53, a set screw 56 screwed into a screw portion 55 of the upper inner hole 54, and a first spring seat 57 in the upper inner hole 54. Further, the lower end that penetrates the nozzle holder 53 has a push rod 59 that comes into contact with the head of the needle 52 via a shim 58 for initial lift adjustment that is slidable in the axial direction of the nozzle holder 53, and a set screw 56.
A first stage valve opening pressure adjusting shim 60 disposed on the lower end surface of the
A first spring 61 stretched between the shim 60 and the first spring seat 57 is provided.

The second adjusting means for adjusting the injection start pressure of the main injection is arranged immediately above the needle 52, and has a lower inner hole 63 provided on the nozzle side of the nozzle holder 53, The second spring seat 64 disposed at the lower end of the lower inner hole 63, slidable in the axial direction of the nozzle holder 53, and having a clearance L1 with the initial lift adjusting shim 58, and the lower inner hole 63. The second stage valve opening pressure adjusting shim 65 disposed on the upper end surface and the shim 65
And a second spring 66 stretched between the second spring seat 64 and the second spring seat 64.

Reference numeral 71 is an oil passage for supplying fuel to the nozzle 51, and 72 is a sliding shoulder 5 above the nozzle 51 and the needle 52.
2a and a spacer 73 having a clearance L2 between the retaining nut and the nozzle holder 53.
4 is a spill bolt, and 75 is a cap nut.

When the pressure applied to the needle 52 increases above a predetermined value due to the fuel pressure from the fuel injection pump introduced into the fuel pressure chamber (not shown) in the nozzle, the initial lift adjusting shim 58 and the push rod 59 are provided. The needle 52 lifts upward by a constant value (initial lift amount) L1 while compressing the first spring 61 via. This is the initial injection, and this state is maintained until the fuel pressure exceeds the set pressure of the second spring 66. Then, while compressing the second spring 66 via the second spring seat 64, the needle 52 is greatly lifted, and main injection for supplying a large amount of fuel is started.

In this way, the initial lift (initial injection)
A gradual fuel injection is performed in which a small amount of fuel is injected during a period and then a large amount of fuel is injected during a main lift (main injection) period.

Although the injection period is set so that NOx and smoke are optimally reduced, the actual injection period may be prolonged or too short.
When the deviation of the injection period occurs particularly in the low and medium load range where the EGR rate is high, the NOx and smoke emission amounts may increase.

To cope with this, in the present invention, when the actual injection period is deviated from the target injection period, the initial lift amount of the fuel injection nozzle 3 is corrected so that the actual injection period matches the target injection period. .

First, in order to make it possible to adjust the initial lift amount L1, in FIG. 10, a stepped portion 73a bored toward the nozzle 51 side is formed on the upper end side of the spacer 73 and the lower end of the second spring seat 64. A ring-shaped piezoelectric element 77 that is expandable and contractable in the axial direction of the nozzle holder 53 is provided therebetween.

A ring-shaped piezoelectric element 78 is also provided between the first stage valve opening pressure adjusting shim 60 and the set screw 56 in order to measure the actual injection period. This is because when the first spring 61 is compressed by the lift of the needle 51 via the push rod 59, the piezoelectric element 78 is distorted by the compressive load, so that the distortion is converted into a voltage to change the actual injection period. It can be measured.

Next, the correction contents of the initial lift amount executed by the control unit 11 will be described with reference to the flowchart of FIG.

At S31 and 32, the actual injection period T is read together with various operating conditions such as the engine speed Ne and the accelerator opening Acc, and at S33 and S34, the basic initial lift amount L _1N and the target injection period T _N are searched by a map search. Ask. In order to obtain the optimum characteristics of the basic initial lift amount shown in FIG. 12 with respect to the torque generated by the engine and the engine speed, FIG.
In order to obtain the optimum characteristics of the target injection period shown in No. 3, a map (not shown) is set with the accelerator opening Acc and the engine speed Ne as parameters, and these maps are searched for and obtained. That is why.

Here, the basic initial lift amount L _1N is as shown in FIG.
As described above, the higher the engine speed and the higher the torque, the larger the value. This is because if the initial lift amount is made small even in the high rotation speed range and the high load range, the injection period becomes long, and as a result, the combustion period is prolonged and the isovolume deteriorates, resulting in poor thermal efficiency (deterioration of fuel efficiency. With this, the smoke emission characteristics also deteriorate), so this is to be avoided.

In S35 of FIG. 11, the actual injection period T and the target injection period T _N are compared, and if they are equal, the flow of FIG. 11 ends. When they are not equal,
In steps S36 and 37, the injection period correction amount ΔT _N is calculated by the formula ΔT _N = T−T _N , and the initial lift correction amount ΔL ₁ is obtained by a table search from the injection period correction amount ΔT _N and the target injection period T _N. . The initial lift correction amount ΔL ₁ is set to the characteristic shown in FIG. 14, and is a value that increases as ΔT _N increases under the condition that T _N is constant, and increases as T _N increases under the condition that ΔT _N is constant. .

A value obtained by adding the correction amount ΔL ₁ to the basic initial lift amount L _1N in S38 is calculated as a target initial lift amount L ₁ , and these are stored in a predetermined address. ΔT _N
Is positive (that is, the actual injection period is longer than the target injection period), the initial lift amount is increased by ΔL _{1 and} vice versa.
When T _N becomes negative (the actual injection period is shorter than the target injection period), the initial lift amount is corrected by ΔL _{1 to the} decreasing side.

For example, when the actual injection period is longer than the target injection period, if the initial lift amount is corrected to the increasing side, the injection rate characteristic changes and the injection period becomes shorter as shown in FIG. This makes it possible to match the actual injection period with the target injection period. On the contrary, when the actual injection period is shorter than the target injection period, the actual injection period can be matched with the target injection period by correcting the initial lift amount to the decreasing side.

In this way, by correcting the initial lift amount of the injection nozzle 3 so that the actual injection period coincides with the target injection period, injection is performed especially in the medium and high load range in the low rotation range where the EGR rate is high. N due to the time lag
It is possible to prevent an increase in the amount of discharged Ox and smoke.

FIG. 16 shows a second embodiment. The illustrated fuel injection pump 81 is an oil feed rate control type fuel injection pump provided with so-called prestroke amount adjusting means (Japanese Patent Laid-Open No. 61-2).
No. 18769). The EGR rate control, swirl ratio control, and injection timing retard control are the same as in the first embodiment.

The pre-stroke amount adjusting means is a control sleeve 86 guided by a plunger 84 as shown in FIG.
The control sleeve 86 moves up and down in the axial direction of the plunger 84 in accordance with the movement of the pin 90 attached to the injection sleeve, thereby changing the prestroke amount of the injection pump. Incidentally, 91 is an actuator (rotary solenoid) for driving the control rod 89, 83
Is a barrel.

The details of the injection pump 81 are as follows.
In FIG. 16, a control sleeve 86 is mounted around the plunger 84, and the position of the control sleeve 86 determines the fuel pumping start timing. The sleeve 85 opens and closes the opening (fuel supply hole) 84b to the fuel chamber side of the passage 84a provided in the axial center of the plunger 84, which connects the fuel chamber 87 into which the fuel is fed and the pressurizing chamber 85, and the plunger 84 When the opening 84b is closed from the lower end of the sleeve 86 in the ascending process, the communication with the fuel chamber 87 is cut off and the pressure in the pressurizing chamber 85 starts to increase. After that, when the pressure of the pressurizing chamber 85 exceeds the valve opening pressure of the discharge valve 88 due to the rise of the plunger 84, the fuel is pumped toward the fuel injection nozzle.

When the port 84c branching from the passage 84a communicates with the spill hoat 86a provided in the middle of the sleeve 86 due to the rise of the plunger 84, the pressurizing chamber 85
Communicate with the fuel chamber 87 again, and the pressure feeding of fuel is completed.

A control rod 8 having an axis in a direction perpendicular to the plane of FIG. 16 and rotatable about the axis.
9 and a notch groove 84c fixed to the control rod 89 and provided on the outer peripheral surface of the control sleeve 86 (see FIG. 17).
By moving the position of the sleeve 86 up and down by the sleeve position adjusting mechanism including the pin 90 that fits into the
The fuel pumping start time can be advanced or delayed.

The branch port 84c is the plunger 84.
Since it is opened as an inclined groove around it, the plunger 84
The rotational position around the axis line of (1) is displaced in the direction perpendicular to the paper surface of FIG. 16 by displacing the rack (plunger rotation adjusting mechanism) 94 engaging with the ball 93 fixed on the sleeve 92, so that the communication timing with respect to the spill hoat 86a is increased. It is possible to change and change the fuel pumping end timing, that is, the fuel injection amount.

Next, FIGS. 18 and 19 show a phase adjusting mechanism 100 for advancing and retarding the cam phase of the fuel injection pump 81 (see Japanese Patent Laid-Open No. 58-48719).

This is the pump shaft (cam shaft) 81a of the fuel injection pump 81 and the rotor 10 to which the engine rotation is transmitted.
The pump shaft 8 for rotating the engine, which is interposed in the connecting portion with 1
The transfer phase for 1a is variably adjusted.

Rotating disk 1 coaxially coupled to pump shaft 80a
The rotating body 101 is rotatably supported by the shaft portion 102 of 03.

Then, in order to impart a phase difference to the rotation transmitted from the rotary body 101 to the rotary disk 103, if necessary,
As a mechanism for connecting the turntable 103 and the rotating body 101 so as to be relatively displaceable in the rotation (circumferential) direction, first, the turntable 103 has a pair of circular holes 103a equidistant from the center of rotation.
The first eccentric cam 105 is inserted therein. In addition, the circular hole 105a provided in the eccentric cam 105
The second eccentric cam 106 is inserted in the.

Eccentric pin 106b of the second eccentric cam 106
Penetrates into the rotating body 101 from the side, and the eccentric pin 105b of the first eccentric cam 105 is connected to the cylinder 107.
It is connected to the piston 107a housed in.

The cylinder 107 is integrally attached to the turntable 103 in the radial direction of the shaft 102, and the oil chamber 107b thereof is provided.
The pressure oil supplied through the inner peripheral passage 102a of the shaft portion 102 is guided to the. The piston 107a moves to a position where this supply pressure and the return spring 107c are balanced.

Therefore, the first eccentric cam 105 is rotated by the eccentric pin 105b according to the position of the piston 107a, which causes the second eccentric cam 106 to rotate.
With respect to the rotation direction, the rotational direction of the rotary body 101 and the rotary disk 103 connected via the eccentric pin 106b is changed.

As a result, the rotational phase of the pump shaft 80a of the fuel injection pump 80, that is, the cam 81, changes with respect to the engine rotation, and the fuel feed rate changes.

The oil pressure from the oil pump 109 guided to the oil chamber 107b of the cylinder 107 changes according to the opening of the control valve 108, and the oil pressure decreases as the opening of the control valve increases.

In the first embodiment, the initial lift amount of the two spring nozzles shown in FIG. 10 is corrected according to the difference between the actual injection period and the target injection period. The fuel feed rate of the fuel feed rate control type fuel injection pump 81 is corrected according to the difference between the actual injection period and the target injection period. In the second embodiment, the 2-spring nozzle is not necessary.

This will be described with reference to the flowchart of FIG. FIG. 20 corresponds to FIG. 11 and includes S41 and S4.
2, S43, S44, S45 and S46 are different from FIG. Description of the same parts as in FIG. 11 is omitted.

Note that S41, S43, and S45 will be described first, and S42, S44, and S46 will be collectively described later.

In S41 of FIG. 20, the basic cam phase DQ _N is obtained by map search. The basic cam phase DQ _N is calculated based on the engine speed Ne and the accelerator opening Acc as shown in FIG.
However, as shown in FIG. 25, the cam speed (lift speed) differs depending on the cam phase of the fuel injection pump. By changing it, it is possible to change the fuel oil feed rate. Even if the fuel pressure feeding period from the fuel injection pump (the period from the communication between the pressurizing chamber 85 and the fuel chamber 87 being blocked by the sleeve 86 until the communication is restarted) is the same, if the cam phase is advanced, the cam speed is increased. Since the high speed region can be used, the oil transfer rate is increased, and conversely, the retarded angle is decreased, the oil transfer rate is decreased. The basic oil feed rate is set to increase as the accelerator opening decreases, and therefore the cam phase advance value is increased in the low accelerator opening range.

At S43, the cam phase correction amount ΔDQ is obtained from the injection period correction amount ΔT _N by a table search, and this cam phase correction amount ΔIT is obtained at S45 as the basic cam phase DQ.
_The cam phase is corrected by adding it to _N , and the corrected value is stored in a predetermined address as the target cam phase DQ.

As shown in FIG. 22, the cam phase correction amount ΔDQ is a value that increases as ΔT _N increases.
For example, when ΔT _N is positive (the actual injection period is longer than the target injection period), the cam phase is corrected by ΔDQ to the advance side (that is, the cam is changed to the left side in FIG. 25 with the pumping start timing being constant). By doing so, the oil feed rate is increased, and the injection period is thereby shortened. Therefore, the actual injection period and the target injection period can be matched. On the contrary, when ΔT _N becomes negative (the actual injection period is shorter than the target injection period), the oil feed rate is reduced (the injection period is lengthened) by the correction of the cam phase delay angle, and the actual injection period is changed to the target injection period. You can match the period.

However, in this injection pump 81, FIG.
As shown in, when the prestroke amount is increased,
While the injection amount remains constant, the injection timing is retarded and the oil feed rate is increased, so even if the actual injection period is made to match the target injection period, Since the injection timing is retarded at the same time when the oil feeding rate is increased by the advance angle correction of S42,
S44 and S46 are provided and correction for that purpose is performed.

Specifically, in S42, the basic prestroke amount P _SN is obtained by map search. A map (not shown) having the accelerator opening Acc and the engine speed Ne as parameters so that the optimum characteristics of the basic prestroke amount shown in FIG. 23 with respect to the torque and the engine speed generated by the engine can be obtained. It is set, and these maps are searched and requested. The pre-stroke amount is usually
Since it is defined by the cam lift amount at the timing of starting the pressure feeding, if the prestroke amount is increased, the injection timing moves to the retard side, so the injection timing is advanced in the high rotation range and the high load range. As described above, the prestroke amount is reduced as the rotational speed and torque increase.

In S44, the prestroke correction amount ΔP _S is obtained by map search from the injection period correction amount ΔT _N and the target injection period T _N, and this prestroke correction amount ΔP _S is S
At 46, the pre-stroke amount is corrected by adding it to the basic pre-stroke amount P _SN , and the corrected value is stored at a predetermined address as the target pre-stroke amount P _S.

[0075] Pre-stroke correction amount [Delta] P _S is and have set the characteristics of FIG. 24, large negative value as [Delta] T _N becomes large in T _N set criteria, also [Delta] T _N is T _N in certain conditions The larger the value, the more negative the value.

In this way, when the oil feed rate is corrected according to the difference between the actual injection period and the target injection period, the prestroke amount is Δ when the actual injection period is longer than the target injection period.
When the pressure feed start timing is shortened by shortening P _{S and the} actual injection period becomes shorter than the target injection period, the pre-stroke amount is increased by ΔP _S and the pressure feed start timing is delayed, so that the actual injection period and the target injection period are reduced. Even when the oil feed rate is corrected so that the two values match, the pressure feed start timing does not change.

In the first embodiment, the distribution type fuel injection pump and the two-spring nozzle have been described, but the present invention is not limited to this, and the present invention is also applied to each of the column type and camshaftless type fuel injection pumps and unit injectors. (These three types of fuel injection pumps are collectively referred to as jerk type fuel injection pumps including unit injectors). Further, in the second embodiment, the case where the oil feed rate control type is applied to the column fuel injection pump has been described, but the present invention is not limited to this, and the fuel feed rate control type may be applied to other fuel injection pumps. Can be applied.

[0078]

According to the first aspect of the present invention, the initial lift amount of the nozzle is determined so that the actual injection period coincides with the target injection period, so that the NOx is accompanied by the deviation of the injection period especially in the high EGR rate state. It is possible to prevent an increase in the amount of smoke and smoke emitted.

In the third aspect of the present invention, the cam phase is determined so that the actual injection period coincides with the target injection period, so that the amount of NOx or smoke emission accompanying the deviation of the injection period particularly in the high EGR rate state occurs. Can be prevented from increasing.

In the fifth aspect of the invention, when the prestroke amount is increased, the injection amount is kept constant, the injection timing is retarded, and the fuel feeding rate is increased. Even when the cam phase is determined so that the actual injection period and the target injection period match, the injection timing does not change.

[Brief description of the drawings]

FIG. 1 is an overall schematic configuration diagram showing a first embodiment of the present invention.

FIG. 2 is a control characteristic diagram of an exhaust gas recirculation rate.

FIG. 3 is an explanatory diagram of swirl generation means.

FIG. 4 is an explanatory view showing the operating state of the same.

FIG. 5 is a control characteristic diagram of a swirl ratio.

FIG. 6 is a sectional view of a distribution type fuel injection pump.

FIG. 7 is a sectional view of part of the same.

FIG. 8 is a control characteristic diagram of fuel injection timing.

FIG. 9 is a control block diagram of fuel injection timing.

FIG. 10 is a sectional view of a two-spring nozzle.

FIG. 11 is a flowchart for explaining correction of an initial lift amount.

FIG. 12 is a control characteristic diagram of a basic initial lift amount L _1N .

FIG. 13 is a control characteristic diagram of a target injection period T _N.

FIG. 14 is a control characteristic diagram of an initial lift correction amount ΔL ₁ .

FIG. 15 is a characteristic diagram of an injection rate.

FIG. 16 is a cross-sectional view of a fuel injection rate control type fuel injection pump of a second embodiment.

FIG. 17 is a perspective view for explaining a prestroke variable mechanism.

FIG. 18 is a sectional view of a main part of a cam phase adjusting mechanism.

FIG. 19 is a front view of a cam phase adjusting mechanism.

FIG. 20 is a flowchart for explaining correction of an oil feed rate.

FIG. 21 is a control characteristic diagram of the basic cam phase DQ.

FIG. 22 is a control characteristic diagram of a cam phase correction amount ΔDQ.

FIG. 23 is a control characteristic diagram of a basic prestroke amount P _SN .

FIG. 24 is a control characteristic diagram of a prestroke correction amount ΔP _S.

FIG. 25 is a cam speed characteristic diagram.

FIG. 26 is an oil transfer rate characteristic diagram.

FIG. 27 is a diagram corresponding to the claim of the first invention.

FIG. 28 is a diagram corresponding to a claim of the third invention.

FIG. 29 is a diagram corresponding to the claim of the fifth invention.

[Explanation of reference numerals] 1 distribution type fuel injection pump 3 2 spring nozzle 11 control unit 77 piezoelectric element (initial lift amount adjusting means) 78 piezoelectric element (actual injection period detecting means) 81 oil feed rate control type fuel injection pump 100 cam Phase adjustment mechanism

Claims (7)

[Claims] 1. A fuel injection control device for a diesel engine including a jerk-type fuel injection pump for pressure-feeding fuel by a plunger, wherein a needle lifts in stages according to the pressure of the pressure-feed fuel, and a nozzle for injecting fuel in multiple stages. Means for adjusting the initial lift amount according to the control amount, means for calculating the target injection period based on the engine speed and load, means for detecting the actual injection period, and this actual injection period and the target injection period A fuel injection control device for a diesel engine, which is provided with means for performing comparison with a period and determining a control amount for the initial lift amount adjusting means so that they match each other. 2. The control amount determining means includes a means for calculating a basic initial lift amount according to an operating condition, a means for calculating an initial lift correction amount according to a difference between an actual injection period and a target injection period, and The fuel injection control device for a diesel engine according to claim 1, further comprising means for determining a value obtained by correcting the basic initial lift amount with an initial lift correction amount as the control amount. 3. A fuel injection control device for a diesel engine equipped with a fuel injection pump that pumps fuel by a plunger, a means for adjusting a cam phase of the fuel injection pump according to a control amount, and a target injection period for the engine. Means for calculating the actual injection period, means for calculating the actual injection period, and comparison between the actual injection period and the target injection period, and control to the cam phase adjusting means so that they match each other. A fuel injection control device for a diesel engine, which is provided with means for determining an amount. 4. The control amount determining means includes means for calculating a basic cam phase according to an operating condition, and means for calculating a cam phase correction amount according to a difference between the actual injection period and the target injection period. The fuel injection control device for a diesel engine according to claim 3, further comprising means for determining a value obtained by correcting the basic cam phase with a cam phase correction amount as the control amount. 5. A means for adjusting a prestroke amount of the fuel injection pump according to a control amount and a comparison between the actual injection period and a target injection period are performed, and the prestroke amount adjustment is performed so that they match each other. 5. A fuel injection control device for a diesel engine according to claim 3, further comprising means for determining a control amount for the means. 6. The control amount determining means calculates a basic prestroke amount according to an operating condition and a prestroke amount correction amount according to a difference between the actual injection period and the target injection period. And a means for determining a value obtained by correcting the basic prestroke amount by the prestroke amount correction amount as the control amount.
The fuel injection control device for the diesel engine according to 1. 7. An exhaust gas recirculation rate controllable means, a swirl ratio controllable means, a fuel injection timing controllable means, a medium speed / medium load range and a low speed full load range. The higher the exhaust gas recirculation rate and the lower the rotation speed, the larger the swirl ratio,
Further, a means for determining each control amount for the three adjusting means is provided so that the fuel injection timing is delayed until after the compression top dead center in a state of a high exhaust gas recirculation rate. 7. The fuel injection control device for a diesel engine according to any one of 1 to 6.