JPH10252530A - Fuel injection control device of diesel engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent remarkable deterioration of output performance by operating a first (second) injection amount for correcting the injection amount of each cylinder in such a manner that during idle stable state (no-load time above medium speed), an engine rotating speed is equal in all cylinders, and modifying and correcting the first and second correction amounts according to the operating condition of an engine. SOLUTION: Detection signals output from an acceleration lever opening sensor 16 and a rotation sensor 17 are input to a control unit, and a fuel injection pump 4 is controlled by the controller to conduct fuel injection control. According to various data of the operating condition, in the case of idle stable state, the rotating speed for every cylinder in a designated crank position is operated. A first injection amount correction amount is operated in such a manner that the rotating speeds of the respective cylinders are the same. At the time of deceleration, in the case of a cylinder injection amount variation operated rotating speed setting region, the second injection amount correction amount is operated in such a manner that the rotating speeds of the respective cylinders are the same. Thus, the injection correction amount is corrected to the operating condition of the engine to improve the output performance.

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, and more particularly, to a fuel injection control device for a diesel engine that corrects an injection amount variation for each cylinder.

[0002]

2. Description of the Related Art As a conventional fuel injection amount correction control technology for each cylinder, there is a technology as disclosed in Japanese Patent Application Laid-Open No. 61-44444. This means that the engine speed at a predetermined crank position before and after combustion in a stable state during idling is detected for each cylinder, and the difference between the detected speeds before and after combustion is determined for each cylinder, and this difference is calculated for all cylinders. A correction amount for correcting the injection amount of each cylinder is calculated and stored so as to be equal, and the correction value of the injection amount is corrected based on the operating state such as the engine speed and the load at that time to obtain a final injection amount. Is calculated.

[0003]

However, in such cylinder-by-cylinder fuel injection amount correction control, a direct injection diesel engine, particularly, a two-stage spring nozzle is used to reduce noise and improve idle stability. Regarding the engine, since the injection amount variation factor for each cylinder during idling is different from, for example, the injection amount variation factor for each cylinder in the full load range, it can be corrected in other operating regions where there is no correlation even when learning at idle. On the contrary, there is a possibility that the output performance is reduced or the exhaust performance is deteriorated.
That is, since the nozzle needle in the injection nozzle does not fully lift at idle, the fuel flow rate is not determined by the injection hole area but by the gap between the injection nozzle body and the nozzle needle. Since the needle is fully lifted, the restriction on fuel flow is the injection hole area. Therefore, as described above, since the injection amount variation factor for each cylinder differs in the full load region from that at the time of idling, learning cannot be performed at the time of idling. The present invention has been made in view of such a conventional problem. In particular, when a two-stage spring nozzle is applied to a direct injection type diesel engine, the pre-lift variation which is a main factor of the injection amount variation for each cylinder is considered. And calculating an injection amount correction amount due to each variation of the fuel flow rate during the full lift of the nozzle needle of the injection nozzle, and correcting the injection amount by correcting the injection amount correction amount according to the operating conditions of the engine. Thus, the above-mentioned problem is solved.

[0004]

According to a first aspect of the present invention, there is provided a diesel engine fuel injection control device for detecting an engine operation state such as an engine speed and an accelerator opening. Means, and an idling stable state judging means for judging whether or not the engine is in an idling stable state by the engine operating state detecting means as input means, and when the idling stable state judging means judges that the engine is in an idling stable state, , The engine speed at a predetermined crank position is detected for each cylinder, and the first correction amount for correcting the injection amount of each cylinder is calculated and stored so that this speed is equal for all cylinders. At no load at or above the speed, the engine speed at the predetermined crank position is detected for each cylinder, and this speed is made equal for all cylinders. In addition, a second correction amount for correcting the injection amount of each cylinder is calculated and stored, and the first correction amount and the second correction amount are corrected according to the operating state of the engine to correct the injection amount. The configuration was adopted. According to a second aspect of the present invention, there is provided a fuel injection control device for a diesel engine.
As described above, the fuel injection control device for a diesel engine has a configuration in which a correction coefficient for optimizing the ratio of the injection amount correction amount based on the first correction amount and the second correction amount depending on the operation region is provided. According to a third aspect of the present invention, in the fuel injection control apparatus for a diesel engine according to the first or second aspect, each of the correction coefficients for correcting the first correction amount and the second correction amount according to an operation region is provided. It was set as the structure provided in. In the fuel injection control device for a diesel engine according to the fourth aspect, in the fuel injection control device for a diesel engine according to the first to third aspects, a nozzle body of the injection nozzle of the diesel engine may include:
While opening and closing the injection hole of the nozzle body, there is a nozzle needle urged in a direction to close the injection hole by a first spring, and an initial lift interval with the nozzle needle above the nozzle needle. The injection system was constituted by a two-stage spring nozzle provided with a push rod urged toward the nozzle needle by a second nozzle spring. According to a fifth aspect of the present invention, there is provided a fuel injection control apparatus for a diesel engine according to any one of the first to fourth aspects, wherein a middle speed no-load stable operation is performed once at the time of deceleration in combination with an automatic transmission. The control is performed so as to perform the speed control. In a diesel engine fuel injection control device according to claim 6, in a diesel engine combined with an automatic transmission and performing pilot injection, the pilot injection is stopped in an idle speed control state during deceleration, and the engine rotation at a predetermined crank position is performed. The number of rotations is detected for each cylinder, and a correction amount for correcting the injection amount of each cylinder is calculated and stored so that the number of revolutions is equal in all cylinders, and the correction amount is stored in accordance with the operating state of the engine. The configuration was modified so that the pilot injection amount was corrected.

[0005]

Hereinafter, the present invention will be described with reference to the drawings. FIG. 1 shows a schematic system of a common embodiment of the invention according to claims 1 to 5. In FIG. 1, an intake throttle valve 9 for controlling an intake air amount is provided in the middle of an intake pipe 2 of a diesel engine main body 1. The diaphragm device 1 is driven by a negative pressure to the intake throttle valve 9.
0, the opening degree is controlled by the negative pressure passage 14 and the pressure regulating valve 13. An air flow meter 24 is provided upstream of the intake throttle valve 9 as means for detecting the amount of intake air. Further, the middle of the intake pipe 2 and the exhaust pipe 3
The EGR valves 5 and 6 are connected to the EGR passages 5 and 6 to control an EGR amount.
Is provided. The EGR valve 7 is driven by the negative pressure, and the opening is controlled by the negative pressure passage 15 and the pressure regulating valve 12. On the other hand, the electric control type fuel injection pump 4 as a fuel injection means is provided with a rotation sensor 17 for detecting an engine rotation speed and an accelerator lever opening sensor 16 for detecting an accelerator lever opening. Also,
An intake throttle valve 20 for controlling intake swirl is provided between the diesel engine main body 1 and the intake manifold 19, that is, at each intake port 19A. In the present embodiment, a case of a diesel engine provided with two intake valves per cylinder is described. One of two intake ports 19A communicating with the two intake valves is a helical port, and the other is a helical port. A tangential port is provided, and an intake throttle valve 20 for controlling intake swirl is provided on the tangential port side, and the opening degree thereof is adjusted to control intake swirl generated in the combustion chamber. The opening degree of the intake throttle valve 20 for controlling the intake swirl is controlled by an actuator 21 having a diaphragm driven by a negative pressure, a negative pressure passage 22, and a pressure regulating valve 23. The above-described negative pressure is supplied by a vacuum pump 8, which is connected to the pressure regulating valves 12, 1 through a negative pressure passage 11.
3 and 23.

[0006] The detection signals output from the rotation sensor 17 and the accelerator lever opening sensor 16 are input to a control unit 18 from which control signals are sent to the pressure regulating valves 12, 13 and 23, respectively. Is output.

Here, the intake throttle valve 9 throttles the intake air during the EGR control to increase the differential pressure between the exhaust pressure and the intake pressure, thereby increasing the pressure E.
This is for EGR control to facilitate GR. The throttle is throttled mainly for improving exhaust gas and taking measures against noise at the time of idling or low load, and at the same time, the opening of the EGR valve 7 is controlled to execute EGR control. It has become so. This E
Specifically, the GR control introduces a negative pressure from the vacuum pump 8 to the diaphragm device 10 via the pressure adjusting valve 13 to throttle the intake throttle valve 9 and, at the same time, controls the duty of the negative pressure to the pressure adjusting valve 12. By controlling the dilution ratio with the atmosphere, the pressure guided to the pressure chamber of the EGR valve 7 is controlled, and the EGR rate is controlled by controlling the opening degree. The above-described EGR rate control and fuel injection control by controlling the fuel injection pump 4 are performed by the control unit 18.

FIG. 2 shows details of the fuel injection pump 4. Reference numeral 31 denotes a pump housing, 32 and 33 denote a low-pressure feed pump and a high-pressure plunger pump driven by a drive shaft 34, and a fuel inlet (not shown). The fuel sucked by the feed pump 32 is supplied to the pump chamber 35 in the pump housing 31 and the pump chamber 3
The air is sent to the plunger pump 33 through the suction passage 36 opening to the side 5. The plunger 37 of the plunger pump 33 has the same number of suction grooves 38 at the tip as the number of cylinders of the engine, and is integrally formed with a face cam 39 having the same number of cam ridges. The face cam 39 rotates together with the drive shaft 34. Roller ring 4
The roller 41 reciprocates by a predetermined cam lift over the roller 41 disposed at 0. Accordingly, the plunger 37 reciprocates while rotating, and with this reciprocating motion, the fuel sucked into the plunger chamber 42 from the suction groove 38 passes through the delivery port (not shown) communicating with the plunger chamber 42 to the delivery valve. Then, it is pressure-fed to the injection nozzle of each cylinder. Then, in order to control the fuel injection timing or the pre-stroke and the injection amount, the pump chamber 35 is controlled.
A fuel passage 43 is formed which communicates with the plunger chamber 42, and a high-speed solenoid valve 44 is interposed in the fuel passage 43. When the valve is opened, the solenoid valve 44 opens the plunger chamber 42.
And is closed for a predetermined period in the discharge stroke of the plunger pump 33 according to the operating condition of the engine according to a signal from the drive circuit 46. Fuel injection is started by closing the solenoid valve 44 during the plunger 37 pumping stroke,
Further, the injection is terminated by opening the solenoid valve 44, so that the fuel injection start timing or the fuel pumping start timing is controlled by the closing timing of the solenoid valve 44, and the injection amount is controlled in accordance with the valve closing period. It is. If the solenoid valve 44 is opened once during the fuel injection process by the plunger pump 33, pilot injection can be performed before the main fuel injection. Reference numeral 45 denotes a fuel cut valve which closes when the engine stops or the like, and reference numeral 47 denotes a distributor head. In the method of controlling the injection timing or the pre-stroke and the injection amount by electronic control, for example, the optimum injection timing or the pre-stroke corresponding to various engine conditions such as the rotation speed, accelerator opening, cooling water temperature, fuel temperature, etc. The injection amount (injection pulse width) is obtained by an experiment or the like, and the value is stored in a storage element such as a ROM of the control device. During actual engine operation, the engine speed is calculated from a signal of one pulse (reference pulse 201) for one rotation of the injection pump and a signal of 36 pulses (scale pulse 202) for one rotation as shown in FIG. The injection timing or the pre-stroke and the injection pulse width are read out in accordance with the rotation speed, the accelerator opening, the coolant temperature, the fuel temperature, and the like, and the injection timing or the pre-stroke and the injection amount are controlled.

As a control of the injection timing, there is an electronically controlled timer piston 120 as shown in FIG. This is to change the phase of the face cam 39 described above. The face cam 39 and the timer piston 120 are connected by a shaft (not shown), and by changing the position of the timer piston 120, the face cam 39 is changed via the shaft. It changes the phase. Timer piston 1
The position control of the high pressure chamber 12 of the timer piston 120
The fuel in the high-pressure chamber 122 is supplied to the timer spring 1 by guiding the fuel of the pump chamber pressure from the pump chamber 35 to the fuel cell 2 and changing the duty ratio of the timing control valve 124.
The position of the timer piston 120 is controlled by changing the amount withdrawn toward the low-pressure chamber 123 having 21.

As a conventional two-stage spring nozzle used in a direct injection diesel engine, for example, FIG.
There is something like that shown in The first in the nozzle holder 508
There is a first spring 512 for step opening pressure and a second spring 510 for second step opening pressure. The needle sliding shoulder 505 above the needle 504 in the nozzle 503 and the spacer 50
6, the nozzle lift (total lift) L2 is determined, and the first-stage lift, that is, the initial lift is determined by the gap L1 between the initial lift gap adjusting shim 507 and the spring seat. The first stage valve opening pressure adjusts the thickness of the first stage valve opening pressure adjusting shim 513, and the second stage valve opening pressure adjusts the thickness of the second stage valve opening pressure adjusting shim 511. Thus, the initial lift amount is determined by adjusting the thickness of the initial lift gap adjusting shim 507. First, the fuel is pumped by the fuel injection pump 4, and high-pressure fuel is introduced from the fuel inlet 501 through the fuel passage in the nozzle holder 508 into the nozzle 503 through a high-pressure fuel pipe (not shown). Then, when the pressure increases, the needle 504 is pushed up against the spring force of the first spring 512 through the gap adjusting shim 507 for initial lift and the push rod 509. This operation continues until the upper end of the initial lift gap adjusting shim 507 contacts the lower end of the spring seat 518. The gap L1 therebetween serves as a first-stage lift, that is, an initial lift. After the contact, the spring seat 518 is pushed up against the spring force of the second spring. And the needle 50
4 until the needle sliding shoulder 505 abuts on the lower end of the spacer 506, after which the needle 504 stops rising. That is, the needle sliding shoulder 5 of the needle 504
A gap L2 between the spacer 05 and the lower end of the spacer 506 serves as a nozzle lift (full lift). In the figure, 502 is a fuel passage, 514 is a set screw, 515 is a cap nut, 516 is a fuel spill hole, 517 is a spill bolt,
519 is a retaining nut.

By the above operation, the initial injection rate can be suppressed without lowering the oil feed rate on the injection pump side by suppressing the lift amount at the initial stage of injection, which is effective for noise reduction. In a direct injection diesel engine, the injection rate of the injection pump is high, so that it is difficult to control the injection amount at the time of idling with a normal single-spring nozzle. Since the injection amount per unit time can be reduced, the idle stability can be improved. As described above, especially in a direct injection type diesel engine in which the injection period is short at idling, the combination with the two-stage spring nozzle is effective to improve the idling stability. However, in all operating conditions, only the initial lift is used. The area is divided into an area, an area of initial lift + all lift, and an area of almost all lift only. During idling operation, only the initial lift is included in this range. Even if the injection amount variation for each cylinder is learned in this region, the initial lift variation for each cylinder is learned, and the total injection Since the variation in the hole area among the cylinders is a factor of the injection amount variation, the variation factors are different, and the learning of the injection amount variation for each cylinder when the idling is stable cannot be used for the correction of the injection amount for each cylinder in the entire operation region. .

Next, the operation will be described. 6 to 8 show flowcharts of the present embodiment. This flowchart shows the case of a combination with an automatic transmission. First, the flowchart for calculating the first injection amount correction amount will be described.

At step 601, the engine speed Ne,
Accelerator lever opening Acc, cooling water temperature Tw, fuel temperature Tf,
The data of the operating conditions such as the air flow meter output Va is read. Next, at step 602, it is determined whether or not the current operating condition is in the idling stable state. If it is determined in step 602 that the vehicle is not in the idle stable state, the process ends. If it is determined in step 602 that the engine is in the idling stable state, in step 603, the rotation speed of each cylinder at a predetermined crank position is calculated. Next, in step 604, the first injection amount correction amount △ Q1 of each cylinder is calculated so that the rotation speed of each cylinder at a predetermined crank position becomes the same. Next, in step 605, RO
M is stored in the predetermined address, and the processing ends.

Next, a flow chart of the calculation of the second injection amount correction amount will be described. In step 701, the engine speed N
e, accelerator lever opening Acc, cooling water temperature Tw, fuel temperature T
f. Read various data of operating conditions such as the air flow meter output Va. Next, at step 702, it is determined whether or not the current operating condition is the time of deceleration. Step 702
If it is determined that the vehicle is not decelerating, the process ends. If it is determined in step 702 that the vehicle is decelerating, it is determined in step 703 whether or not it is in a cylinder-by-cylinder injection amount variation calculation rotation speed setting area. Step 703
If it is determined that the rotation speed is not in the cylinder-by-cylinder injection amount variation calculation rotation speed setting region, the process ends.

If it is determined in step 703 that the engine speed is within the cylinder-by-cylinder injection amount variation calculation rotational speed setting area, then in step 704, the cylinder-by-cylinder injection amount variation calculation rotational speed is set. Next, in step 705, the rotation speed of each cylinder at a predetermined crank position is calculated. Next, step 7
At 06, the second injection amount correction amount △ Q2 of each cylinder is calculated so that the rotation speed of each cylinder at a predetermined crank position becomes the same. Next, in step 707, the data is stored at a predetermined address in the ROM, and the processing ends.

Finally, a calculation flowchart of the injection amount correction amount under each operating condition will be described. In step 801,
Various data of operating conditions, such as the engine speed Ne, the accelerator lever opening Acc, the cooling water temperature Tw, the fuel temperature Tf, and the air flow meter output Va, are read. Next, step 802
Then, the first injection amount correction amount ８０Q1, the second injection amount correction amount △ Q2, the area correction coefficient K, the first correction coefficient K1, and the second correction coefficient K2 are calculated based on the data read in step 801. . The first injection amount correction amount １Q1 and the second injection amount correction amount △ Q
2 reads the learning value from the ROM, and the area correction coefficient K, the first correction coefficient K1, and the second correction coefficient K2 are, for example, as shown in FIGS.
Characteristics such as 2 are stored in advance. Here, the area correction coefficient K is a coefficient for correcting whether the current operation area has a larger injection amount ratio in the above-described initial lift area or the entire lift area. It is getting smaller. The first correction coefficient K1 and the second correction coefficient K2 are coefficients for correcting the first injection amount correction amount ΔQ1 and the second injection amount correction amount ΔQ2, respectively, based on the engine speed and the load. Next, in step 803, based on the value read in step 802, the injection amount correction amount △ Q
Is calculated by the following equation: ΔQ = K × ΔQ1 × K1 + (1−K) × ΔQ2 × K2. In step 804, the result is stored in a predetermined address of the ROM, and the processing is ended. Further, as described above, the fuel injection pump can also perform pilot injection for noise reduction or the like. Since the pilot injection has a small injection quantity, the sensitivity of the combustion variation due to the variation of the injection quantity for each cylinder is very large, and the effect when control can be performed with high accuracy is great, but conversely, the deterioration rate when the injection quantity varies. Is also big. Therefore, at the time of deceleration, the pilot injection is stopped, and as a single-stage injection, the injection amount variation for each cylinder is corrected in the same manner as above, and the cylinder-to-cylinder variation of the pilot injection amount and the cylinder-to-cylinder variation of the main injection amount are corrected. Is also possible.

[0017]

As described above, the injection amount correction amount due to the pre-lift variation, which is the main factor of the injection amount variation for each cylinder, and the fuel flow variation at the time of full lift of the nozzle needle of the injection nozzle is calculated. And
In addition, by correcting the injection amount correction amount according to the engine operating condition and correcting the injection amount, engine vibration,
It is possible to prevent the output performance and the smoke emission characteristics from being significantly deteriorated.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic system of an embodiment.

FIG. 2 is a diagram showing details of a charge injection pump of the present embodiment.

FIG. 3 is an explanatory diagram showing a reference pulse and a scale pulse of the present embodiment.

FIG. 4 is a diagram showing an electronically controlled timer piston of the present embodiment.

FIG. 5 is a view showing a two-stage spring nozzle used in a direct injection diesel engine.

FIG. 6 is a flowchart illustrating the present embodiment.

FIG. 7 is a flowchart illustrating the present embodiment.

FIG. 8 is a flowchart illustrating the present embodiment.

FIG. 9 is a diagram showing a relationship between engine speed and torque.

FIG. 10 is a diagram showing a relationship between an engine speed and a region correction coefficient K.

FIG. 11 is a diagram illustrating a relationship between an engine speed and a first correction coefficient K1.

FIG. 12 is a diagram illustrating a relationship between an engine speed and a second correction coefficient K2.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Diesel engine 2 Intake pipe 3 Exhaust pipe 4 Fuel injection pump (I / P) 5 EGR passage 6 EGR passage 7 EGR valve 8 Vacuum pump 9 Throttle valve 10 Diaphragm device 11 Negative pressure passage 12 Pressure regulating valve 13 Pressure regulating valve 14 Negative Pressure passage 15 Negative pressure passage 16 Accelerator lever opening sensor 17 Rotation speed sensor 18 Control unit 19 Intake manifold 20 Intake throttle valve 21 Actuator 22 Negative pressure passage 23 Pressure regulating valve 24 Air flow meter 31 Pump housing 32 Feed pump 33 Plunger pump 34 Drive Shaft 35 Pump chamber 36 Suction passage 37 Plunger 38 Suction groove 39 Face cam 40 Roller ring 41 Roller 42 Plunger chamber 43 Fuel passage 44 Solenoid valve 45 Fuel cut valve 46 Drive circuit 47 Distributor head 120 Timer piston 121 Timer spring 122 High pressure chamber 123 Low pressure chamber 124 Timing control valve 501 Fuel inlet 502 Fuel passage 503 Nozzle 504 Needle 505 Needle sliding shoulder 506 Spacer 507 Initial lift gap adjusting shim 508 Nozzle holder 509 Push Rod 510 Second spring 511 Second stage valve opening pressure adjusting shim 512 First spring 513 First stage valve opening pressure adjusting shim 514 Set screw 515 Cap nut 516 Fuel spill hole 517 Spill bolt 518 Spring seat 519 Retaining nut

Claims (6)

[Claims] 1. An engine operating state detecting means for detecting an engine operating state such as an engine speed and an accelerator opening, and an idle stable state determining means for determining whether the engine is in an idle stable state by the engine operating state detecting means. Means, the idle stable state determination means,
When it is determined that the engine is in the idling stable state, the first correction amount for detecting the engine speed at the predetermined crank position for each cylinder and correcting the injection amount of each cylinder so that this speed is equal in all cylinders. Is calculated and stored, and when no load is applied at a medium speed or higher, the engine speed at a predetermined crank position is detected for each cylinder, and the injection amount of each cylinder is set so that this speed is equal in all cylinders. A diesel engine characterized by calculating and storing a second correction amount to be corrected, correcting the first correction amount and the second correction amount according to the operating state of the engine, and correcting the injection amount. Fuel injection control device. 2. The fuel injection of a diesel engine according to claim 1, wherein a correction coefficient for optimizing a ratio of the injection amount correction amount based on the first correction amount and the injection amount correction amount according to the operation region is provided. Control device. 3. A diesel engine fuel injection control device according to claim 1, wherein a correction coefficient for correcting the first correction amount and the second correction amount is provided for each operation region. 4. A nozzle needle urged in a nozzle body of an injection nozzle of the diesel engine to open and close an injection hole of the nozzle body and to be urged in a direction to close the injection hole by a first spring. An injection system is constituted by a two-stage spring nozzle in which the nozzle needle and a push rod urged toward the nozzle needle by a second nozzle spring with an initial lift interval are provided above the nozzle needle. 4. The fuel injection control device for a diesel engine according to claim 1, wherein: 5. The fuel injection of a diesel engine according to claim 1, wherein in combination with an automatic transmission, during deceleration, control is performed such that the medium speed no-load stable operation is performed once, and then idle speed control is performed. Control device. 6. In a diesel engine combined with an automatic transmission and performing pilot injection, the pilot injection is stopped in an idle speed control state during deceleration, and the engine speed at a predetermined crank position is detected for each cylinder. A correction amount for correcting the injection amount of each cylinder is calculated and stored so that the number of rotations becomes equal in all the cylinders, and the correction amount is corrected according to the operating state of the engine. And a fuel injection control device for a diesel engine.