JPH11247704A - Fuel injection timing controller of engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce storing and processing load of a controller by finding the target injection timing to be gradually changed by the coefficient and the calculation using the coefficient when the fuel injection timing is largely changed. SOLUTION: When the basic injection timing SOIbs is suddenly advanced at the time t1 , the fuel injection correction amount found by multiplying the difference ΔSOI1 between the basic injection timing and the just before target injection timing by the damping coefficient Kdmp (0.5) is added to the just before target injection timing, and the next damping correction injection timing SOId1 corrected to the advance side is found. Hereinafter, the similar processing is performed. When the difference becomes a judged value or less, the basic injection timing SOIbs is taken as the damping correction injection timing. A controller has only load of storage and calculation of the damping coefficient Kdmp, and it is not necessary to store many injection timing data in advance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection timing control device for an engine which suppresses a rapid change in the fuel injection timing of the engine.

[0002]

2. Description of the Related Art In recent years, as an electronically controlled fuel injection system for a diesel engine, by controlling a fuel injection amount, a fuel injection timing, and a fuel injection pressure, engine characteristics including output and fuel consumption and engine exhaust gas have been developed. Various types with improved characteristics have been developed. The fuel injection system for such an engine includes a needle valve that moves up and down in the main body to open and close an injection hole, and an electromagnetic valve that is supplied with a drive current for controlling the pressure action of a working fluid to move the needle valve up and down. The fuel injection timing, the injection amount, and the injection pressure of the fuel injected from the injector into the combustion chamber are controlled by the controller according to the operating state of the engine.

In such an electronically controlled combustion injection system, the basic injection timing is calculated for the fuel injection timing by referring to a predetermined map based on the engine speed and the fuel injection amount. The final target injection timing is determined by performing various corrections based on the water temperature, the intake air temperature, and the like. Therefore, when the engine speed or the fuel injection amount changes suddenly as in the case of acceleration / deceleration operation, the basic injection timing and the final target injection timing change suddenly, and the combustion state and drivability of the engine change suddenly.
It may cause discomfort to the driver.

[0004] In order to prevent such a change in the combustion state of the engine, there is a control for gradually advancing the fuel injection timing to a target injection timing during acceleration operation, that is, performing a damping control of the fuel injection timing. (As an example, Tokuho 3
-50899). The technology disclosed in this publication detects the degree of acceleration, that is, the acceleration, and increases the advance angle of the fuel injection timing at the time of rapid acceleration, and decreases the advance angle of the fuel injection timing at the time of gentle acceleration, thereby increasing the acceleration speed. The fuel injection timing is controlled in accordance with the reduction of the generation amount of NOx and white smoke.

In the control of the fuel injection timing, in order to determine the advance angle speed in accordance with the stepwise acceleration such as rapid acceleration or gentle acceleration, the optimum fuel injection timing is determined in advance in accordance with such acceleration. It is necessary to store the calculated fuel injection timing in the memory of the controller. In order to determine the optimal fuel injection timing in advance, it is necessary to repeat a number of experiments, and it takes a lot of effort and cost to develop the engine. Also, even if the advance angle is determined according to the stepwise acceleration rate, the fuel injection timing is controlled at the same advance rate for a certain range of acceleration rate. Then
Optimum control of the advance speed, such as taking a long time by performing many corrections of the fuel injection timing until the actual fuel injection timing reaches the target fuel injection timing, or performing rapid advance control Can not.

[0006]

Therefore, a large amount of fuel injection timing information is stored in advance in accordance with the acceleration level, and the stored fuel injection timing is read out to deal with the acceleration level stepwise. Rather than adopting the method described above, the solution is to determine the optimal fuel injection timing according to the acceleration state by performing the optimum advance or retard control according to the acceleration level by calculation for any acceleration level. There are issues to be addressed.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problem, and it is possible to calculate an acceleration and deceleration of an engine regardless of the degree of acceleration when the engine is operated. It is an object of the present invention to provide a fuel injection timing control device for an engine, which can obtain an optimum fuel injection timing and can reduce a load on a memory and a CPU of a controller.

According to the present invention, there is provided a basic injection timing calculating means for calculating a basic injection timing for injecting fuel in accordance with an engine speed and a target fuel injection amount, and calculating a difference between the basic injection timing and the immediately preceding target injection timing. Difference calculating means for calculating, determining means for determining whether the difference exceeds a predetermined determination value, and, when the difference exceeds the determination value,
An injection timing correction amount is obtained by multiplying the difference by a coefficient, and the immediately preceding target injection timing is corrected according to the injection timing correction amount to calculate the next damping correction injection timing, and the difference exceeds the determination value. If not,
The present invention relates to a fuel injection timing control device for an engine, comprising: a damping correction injection timing calculating means for setting the basic injection timing to the next damping correction injection timing.

In the fuel injection timing control device for an engine, the coefficient is a value smaller than one. An injection timing correction amount that is always smaller than the difference calculated by the difference calculation means is obtained.

Since the present invention is configured as described above, it operates as follows. That is, the basic injection timing calculation means calculates the basic injection timing for injecting fuel according to the engine rotation speed and the target fuel injection amount, which is the operating state of the engine at that time. The target fuel injection amount is usually determined based on data such as a map determined in advance corresponding to the rotation speed of the engine and the accelerator depression amount. The difference calculating means calculates a difference between the basic injection timing calculated by the basic injection timing calculating means and the target injection timing immediately before calculated by the target injection timing calculating means. The determining means determines whether the difference exceeds a predetermined determination value. If the difference exceeds the judgment value, the damping correction injection timing calculation means
An injection timing correction amount is obtained by multiplying the difference by a coefficient, and the immediately preceding target injection timing is corrected according to the obtained injection timing correction amount to calculate a damping correction injection timing of the next period.
If the difference does not exceed the determination value, the basic injection timing calculated by the basic injection timing calculation means is set as the next damping correction injection timing. Therefore, if the difference between the basic injection timing and the immediately preceding target injection timing exceeds the determination value, the difference is multiplied by a predetermined coefficient to determine the injection timing correction amount. And the damping correction injection timing is obtained only by the calculation using the coefficient.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an engine fuel injection timing control device according to the present invention will be described below with reference to the accompanying drawings. FIG. 4 is a schematic diagram of an entire system including an engine fuel injection system to which the engine fuel injection timing control device according to the present invention is applied. Engine 1
Although only one injector 11 is shown in FIG. 4, the engine 1 is a multi-cylinder four-cycle direct-injection diesel engine such as a four-cylinder engine for obtaining high output. The engine 1 has a cylinder block 2 and a cylinder head 3. The reciprocating motion of a piston 4 slidable in a cylinder liner formed in the cylinder block 2 and the rotating motion of a crankshaft 6 connect the two. It is converted via the connecting rod 5.

Electronically controlled fuel injection system 1 for engine 1
0 is a hydraulically operated unitized injector 1
1 is adopted. The injector 11 is disposed in the cylinder head 3, operates with engine oil as a working fluid, and injects fuel directly into the combustion chamber 7 by increasing the pressure of the fuel to a predetermined fuel injection pressure. I do. The fuel whose pressure has been increased to a relatively low pressure by the fuel pump 12 is supplied to a pressure increasing chamber (not shown) formed inside the injector 11 through a fuel supply pipe 13. The engine oil is pressurized to a high pressure by a high-pressure oil pump 14, accumulated in a high-pressure oil manifold (oil rail) 15, and supplied from the high-pressure oil manifold 15 to a pressure chamber (not shown) in each injector 11. The high-pressure engine oil supplied to the pressure chamber acts on a pressure-intensifying plunger (not shown) to cause a stroke of the pressure-increasing plunger,
The fuel in the pressure intensifying chamber is increased in pressure and injected from an injection hole formed at the tip of the injector 11.

The electronically controlled fuel injection system 10 includes a controller 20 as an electronic control unit (ECM). The controller 20 receives a detection signal from each detecting means for detecting the operating state of the engine 1, The controller 20 controls the high-pressure oil pump 14, the flow control valve 16, the injector 11 based on these detection signals.
Of the electromagnetic valve 17 and the like are controlled.

Specifically, the detecting means for detecting the operating state of the engine 1 inputted to the controller 20 includes the following. Rotation speed Ne of engine 1
The crank angle sensor 21 detects the gear 8 (having 57 teeth at equal intervals) which is fixed to the crankshaft 6 and rotates and has a missing tooth (3 teeth) 9 in a part of the periphery. It consists of an electromagnetic pickup. From the number of times the missing tooth (for three teeth) portion 9 is detected and the time required for it,
The rotation speed of the crankshaft 6 is determined. The accelerator depression amount sensor 22 for detecting the accelerator depression amount (or the accelerator opening) Ac includes a potentiometer for detecting the depression stroke of the accelerator pedal. The engine temperature sensor for detecting the engine temperature is a water temperature sensor 23 (or an oil temperature sensor for detecting the lubricating oil temperature) which is provided on the cylinder head 3 and detects the cooling water temperature Tw circulating through the cylinder head 3. . Cooling water temperature Tw
Can be used as a representative value of engine friction. Further, in order to detect the rail pressure and the oil temperature in the high-pressure oil manifold 15, the high-pressure oil manifold 15 is provided with a pressure sensor 24 and a temperature sensor 25.

The intake pipe 26 of the engine 1 has an intake pipe 26
An intake pressure sensor 27 for detecting the intake pressure of the intake air and an intake air temperature sensor 28 for detecting the intake air temperature are provided.
The opening of the intake throttle valve 29 provided in the intake pipe 26 is controlled by a control signal from the controller 20, and the position of the throttle valve is detected by a position sensor 30. In order to reduce NOx, the engine 1
An EGR (exhaust gas recirculation) pipe 32 for recirculating a part of the exhaust gas to the intake pipe 26 is connected between the exhaust pipe 31 and the intake pipe 26. The valve lift position of the EGR valve 33 provided in the middle of the EGR pipe 32 is determined by the controller 2
0 is controlled by using a negative pressure of a vacuum pump 34 as a vacuum source whose introduction is controlled by a pressure regulating valve (EVRV) 35 controlled by 0, and the valve lift position is detected by a pressure sensor 36 as a valve lift negative pressure. . Further, the controller 20 includes a shift position sensor 37 of the automatic transmission and a warm-up switch 3 operated to promote warm-up of the engine 1.
8, and a signal from an air conditioner switch 39 as an auxiliary machine are also input.

The injection pressure of the fuel injected from the injector 11 is the pressure in the high-pressure oil manifold 15, that is,
Determined by oil rail pressure. The oil rail pressure in the high-pressure oil manifold 15 is controlled by controlling the opening of a flow control valve 16 attached to the high-pressure oil pump 14 to control the amount of oil leaked from the flow control valve 16. The flow control valve 16 is a normally open or normally closed control valve. The opening of the flow control valve 16 is controlled by, for example, a duty ratio of a control pulse current which is a control signal from the controller 20.

The injector 11 is provided with a solenoid valve 17, and the solenoid valve 17 is provided with a high-pressure oil manifold 1
5 is arranged in an oil path from the oil chamber to the pressure chamber in the injector 11. By opening and closing the solenoid valve 17, the supply of high-pressure oil in the high-pressure oil manifold 15 to the pressure chamber in the injector 11 and the discharge from the pressure chamber are controlled, and the high-pressure oil supplied to the pressure chamber is increased in pressure. A pressure action is exerted on the plunger to increase the pressure of the fuel in the pressure intensifying chamber and perform fuel injection.

By controlling the operation of the solenoid valve 17 by the timing and duration of the control current supplied from the controller 20, the timing and duration of supply of high-pressure oil to the pressure chamber in the injector 11 are controlled.
The injection timing and the injection amount of the fuel injected from the fuel cell are controlled. That is, the controller 20 determines the energization period (pulse width) to the solenoid valve based on the target fuel injection amount determined by the calculation of the target fuel injection amount, and energizes the solenoid valve with this pulse width to thereby control the fuel. The injection amount is controlled. The crank angle detected by the crank angle sensor 21 is supplied to the solenoid valve 17 together with a detection signal of each sensor for detecting that the piston has reached the compression top dead center of the reference cylinder or each cylinder or a predetermined position before the compression top dead center. It is used for controlling the energization start timing and energization period of the driving current to be driven. The structure of the injector 11 having the pressure-increasing plunger and the fuel injection system itself having the injector can be, for example, those disclosed in Japanese Patent Application Laid-Open No. 6-511526. However, the fuel injection timing control device for an engine according to the present invention is not limited to the fuel injection system having the above-described injector, but includes a pressure control chamber to which high-pressure fuel is supplied and a needle valve for fuel pressure. Of course, the present invention is also applicable to an injector of a type that moves up and down.

FIG. 1 is a conceptual diagram showing the calculation of the target fuel injection timing applied to the engine fuel injection timing control device according to the present invention. The calculation of the fuel injection timing is performed by the controller 20. Basic injection timing calculation means 4
0 indicates the basic injection timing SOIb with reference to data such as a predetermined map based on the engine rotation speed Ne and the target fuel injection amount Q, which are the operating state of the engine at that time.
s (SOI; Start Of Inject)
tion). Note that the target fuel injection amount Q usually corresponds to the engine rotation speed Ne and the accelerator depression amount Ac,
It is calculated with reference to data such as a predetermined map.

The damping correction injection timing calculating means 41
This is calculation means for performing damping correction of the fuel injection timing in the present invention. Damping correction injection timing calculation means 41
Indicates a basic injection timing SOIbs calculated by the basic injection timing calculation means 40 and a target injection timing calculation means 42 (described later).
Is calculated by multiplying the difference ΔSOI from the immediately preceding target injection timing SOIb by a coefficient, to obtain an injection timing correction amount, and corrects the immediately preceding target injection timing SOIb according to the injection timing correction amount to perform the next damping correction. Is calculated. The coefficient is a predetermined value and is set to a value smaller than 1. In addition, as the injection timing immediately before obtaining the difference ΔSOI from the basic injection timing SOIbs, the immediately preceding target injection timing SOIbs
Instead of Ib, the target injection timing SOIb immediately before calculated by the damping correction injection timing calculation means 41 may be adopted.

The target injection timing calculating means 42 calculates the damping correction injection timing SOId calculated by the damping correction injection timing calculating means 41 based on the cooling water temperature Tw detected by the water temperature sensor 23 and the intake air temperature Tboost detected by the intake air temperature sensor 28.
The final target injection timing SOI is calculated by making corrections based on various operating states such as. The controller 20 repeatedly executes the calculation in each of the calculation means 40 to 42 at a constant time cycle. The controller 20 determines the timing of energizing the drive current to the solenoid valve 17 of the fuel injection system 10 based on the target injection timing SOI obtained by the calculation performed in this manner, and determines the determined energization timing. At this time, the solenoid valve 17 is energized to control the fuel injection timing from the injector 11.

FIG. 2 is a flowchart showing a calculation routine for determining the fuel injection timing at which fuel is injected in the engine fuel injection timing control device according to the present invention. This routine is executed by the damping correction injection timing calculating means 41 shown in FIG. This flowchart is
It comprises the following steps (S1 to S4). (1) The difference between the basic injection timing SOIbs calculated by the basic injection timing calculation means 40 and the immediately preceding target injection timing SOIb calculated by the target injection timing calculation means 42 is calculated, and ΔSO
Substituted into I (S1). (2) It is determined whether or not the absolute value of the difference ΔSOI calculated in S1 exceeds a predetermined difference determination value, SOILv (S2). (3) As a result of the determination in S2, the difference ΔSO calculated in S1
If the absolute value of I exceeds the determination value SOILv,
Since the change in the fuel injection timing is large, the damping correction should be performed.
1 is a predetermined damping coefficient K for the difference ΔSOI.
dmp (for example, 0.5) is added to the immediately preceding target injection timing SOIb to obtain the immediately preceding target injection timing SIb.
OIb is corrected so that the next damping correction injection timing SO
Id is obtained (S3). The fact that the absolute value of the difference ΔSOI exceeds the predetermined difference level SOILv is a condition for executing the correction of the injection timing by the damping correction injection timing calculation means 41. (4) As a result of the determination in S2, the difference ΔSO calculated in S1
If the absolute value of I does not exceed the determination value SOILv, the change in fuel injection timing is small and it is not necessary to perform damping correction. (S4). Difference Δ
The fact that the absolute value of the SOI falls below the determination value SOILv is an escape condition for the correction of the injection timing by the damping correction injection timing calculation means 41. The target injection timing calculating means 42 calculates the final target injection timing SOI for the damping correction injection timing SOId calculated by the above calculation routine. The next target injection timing SOIb becomes the immediately preceding target injection timing SOIb when the next calculation routine is executed.

FIG. 3 is a graph showing how the target injection timing SOI changes over time when the fuel injection timing calculation routine shown in FIG. 2 is executed. Here, the target injection timing SOI is the time before compression top dead center (positive in the upward direction), and the damping coefficient Kdmp is set to 0.5. The calculation time is executed every Δt. At time t ₁ , it is assumed that the basic injection timing SOIbs calculated by the basic injection timing calculation means 40 rises stepwise greatly. Basic injection timing SOIbs and differential DerutaSOI ₁ between the target injection timing SOIb immediately before the target injection timing calculating means 42 is calculated is determined (S1), the difference DerutaSOI ₁ is determined to be greater than a predetermined determination value SOILv (S2), the damping correction injection timing calculating means 4
1, are multiplied by a damping coefficient Kdmp the difference DerutaSOI ₁ is added to immediately before the target injection timing SOIb, calculates the result as damping correction injection timing SOID ₁ of the next (S3; however, the coolant temperature Tw and the intake air temperature Tboos
t is not corrected).

At the next operation time t ₂ , the routine shown in FIG. 2 is repeatedly executed. That is, the target injection timing SOID ₁ next to the immediately preceding, is greater than the difference _{ΔSOI 2 (= SOIbs-SOId 1} ) is still level SOILv the basic injection timing SOIbs (S2), ΔSO
SOID ₂ obtained by adding the value obtained by multiplying the damping KDMP to I ₂ in _{SOId 1 (= SOId 1 + Kdmp} × ΔS
OI ₂ ) as the next damping correction injection timing (S
3). Thereafter, the same processing as described above is repeated until the difference between the target injection timing and the basic injection timing SOIbs becomes smaller than the level SOILv, and the target injection timing is gradually advanced. At time t _n , the basic injection timing S
The difference DerutaSOI _n with OIbs is determined to be smaller than the level SOILv (S2), damping correction injection timing SOID _n the next is set to the basic injection timing SOIbs (S4).

In the above case, the basic injection timing SOIbs
Is the injection timing control in the case where the basic injection timing SOIbs is greatly retarded in a stepwise manner, the target injection timing is gradually retarded at the angle before the top dead center. . FIG. 3, at time t _m, state of the target injection timing changes are shown in the case of the basic injection timing SOIbs fell sharply in steps. The difference ΔSOI between the target injection timing and the basic injection timing SOIbs becomes a negative value, and the addition processing in S3 is a subtraction.

As described above, in the control of the fuel injection timing according to the present invention, the difference between the basic injection timing and the immediately preceding target injection timing is multiplied by a predetermined coefficient to thereby perform the injection for the next damping correction injection timing. Since the amount of timing correction is obtained, the time required to reach the basic injection timing, as seen in the conventional case where the value of the difference is divided into two stages and the advance angle is corrected in stages, is observed. The number of corrections of the injection timing does not increase or the abrupt advance / retard control is not performed, but converges on the basic injection timing with the appropriate number of corrections. The damping coefficient Kdmp is set to 0.5 in the above embodiment, but is not limited to this. It can be changed depending on the value of the difference ΔSOI. That is, too high ΔSO
For I, the correction width of the injection timing can be adjusted by reducing the damping coefficient Kdmp or the like. Furthermore,
In the calculation routine for obtaining the fuel injection timing, in S2, the determination value SOILv is fixed, but the determination value when entering the correction of the injection timing after S3 is set to be smaller than the determination value when exiting from the correction of the injection timing. It can be set large. In the above embodiment, the damping coefficient Kd
Although mp and the determination value SOILv are set to the same value when the injection timing is advanced and when the injection timing is retarded, they may be set to different values.

[0027]

The fuel injection timing control device for an engine according to the present invention is constructed as described above, and the damping correction injection timing calculating means includes a basic injection timing determined according to the operating state of the engine and a target injection timing immediately before. If the difference from the injection timing exceeds the determination value, an injection timing correction amount is obtained by multiplying the difference by a damping coefficient, and the immediately preceding target injection timing is corrected according to the injection timing correction amount to correct the next damping correction injection timing. If the above difference does not exceed the judgment value, the basic injection timing is set to the next damping correction injection timing. Therefore, whatever the acceleration is, the basic injection timing is calculated according to the degree of the acceleration. It is possible to determine the fuel injection timing that provides optimal advance or retard control, and it takes time to reach the target fuel injection timing, There is no possibility to be controlled. In addition, since a method of previously obtaining a large number of fuel injection timings in a stepwise manner with respect to the degree of acceleration and storing them in the memory is not adopted, the load on the memory and the CPU of the controller can be reduced.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of calculation for calculating a target injection timing applied to an engine fuel injection timing control device according to the present invention.

FIG. 2 is a flowchart showing a calculation routine for obtaining a target injection timing in the engine fuel injection timing control device according to the present invention.

FIG. 3 is a graph showing an example of a change in a target injection timing when a calculation routine for calculating an injection timing of an engine shown in FIG. 2 is executed.

FIG. 4 is a diagram showing an example of an electronically controlled fuel injection system to which the engine fuel injection timing control device according to the present invention is applied;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Engine 10 Electronic control fuel injection system 11 Injector 14 High pressure oil pump 15 High pressure oil manifold 17 Solenoid valve 20 Controller 40 Basic injection timing calculation means 41 Damping correction injection timing calculation means 42 Target injection timing calculation means Ne Engine speed Q Target fuel injection Amount SOIbs Basic injection timing SOIb Target injection timing immediately before SOId Next damping correction injection timing ΔSOI difference SOILv Judgment value Kdmp Damping coefficient

Claims (2)

[Claims] 1. A basic injection timing calculating means for calculating a basic injection timing for injecting fuel in accordance with an engine speed and a target fuel injection amount, and calculates a difference between the basic injection timing and the immediately preceding target injection timing. Difference calculating means, determining means for determining whether the difference exceeds a predetermined determination value, and when the difference exceeds the determination value, the difference is multiplied by a coefficient to reduce the injection timing correction amount. And calculating the next damping correction injection timing by correcting the immediately preceding target injection timing according to the injection timing correction amount.
An engine fuel injection timing control device for an engine, comprising: damping correction injection timing calculation means for setting the basic injection timing to the next damping correction injection timing when the difference does not exceed the determination value. 2. The fuel injection timing control system for an engine according to claim 1, wherein said coefficient is smaller than 1.