JPH11236838A - Electronic control fuel injection device for diesel engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To dissolve the peak feeling of acceleration/deceleration at the sudden change time of an accelerator opening by deciding an injection increase/decrease amout by mulitiplying a prescribed coefficient to the difference between a basic target injection amount and prior target injection amount and also deciding the value added with this injection increase/decrease amount to prior target injection amount as a this time target injection amount. SOLUTION: When the fuel injection is controlled by ECM 2 for inputting the output signals of various kind of sensors for detecting a running state, at first, a basic target injection amount is calculated based on the respective detection signals of a rotational speed sensor 6 and accelerator opening sensor 8. Then, the damping target injection amount of acceleration/deceleration is decided after comparing this basic target injection amount with a prior target injection amount and then, various kind of correction is carried out on the damping target injection amount based on an intake pressure, water temperature, oil pressure and oil temperature and a final target injection amount is decided. In the prescribed crank angle before the fuel injection of respective cylinders, the pulse width of a solenoid valve in an injector 16 is decided based on the final target injection amount and the fuel is jetted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronically controlled fuel injection device for a diesel engine, and more particularly to an electronically controlled fuel injection device for a diesel engine that determines a target injection amount based on the operating state of a vehicle.

[0002]

2. Description of the Related Art In an electronically controlled fuel injection device for a diesel engine, a basic target injection amount is calculated (refer to a map) from a rotation speed and a load (mainly, an accelerator opening), and various basic values based on a water temperature, an intake pressure, etc. The final target injection amount of fuel is determined by making a correction.

[0003] During a transient (acceleration / deceleration) operation, the accelerator opening rapidly changes, so that the basic target injection amount and the final target injection amount change suddenly, and an acceleration / deceleration shock occurs because the engine speed cannot follow these. In order to prevent this, a control (acceleration / deceleration damping control) for gradually increasing / decreasing the target injection amount is disclosed in Japanese Patent Publication No. Hei 5-34498.

In Japanese Patent Publication No. 5-34498, a basic target injection amount is obtained from a map at the time of engine acceleration based on the engine speed and the accelerator opening. Then, the basic target injection amount is compared with a corrected injection amount obtained by adding a predetermined allowable increase amount according to the change amount of the accelerator opening to the previous target injection amount, and the smaller one is compared with the current target injection amount. Acceleration / deceleration damping control. further,
The final target injection amount of this time is determined by correcting this based on the water temperature, the intake pressure, and the like.

As a result, the injection amount during acceleration is gradually increased by an allowable increase amount, thereby preventing shock and smoke. Further, in Japanese Patent Publication No. Hei 5-34498, the driving fee in the damping control is changed by changing the allowable increase amount (the rapid acceleration increase amount> the gentle acceleration increase amount) according to the acceleration amount (the change amount of the accelerator opening). The ring is being improved.

[0006]

SUMMARY OF THE INVENTION
In the conventional damping control represented by No. 98, an optimum allowable increase amount must be set in advance for each of various operation states (the above-mentioned acceleration amount: the amount of change in the accelerator opening), and includes experiments and the like. It takes a lot of time (cost) for development.

[0007] Further, since it is necessary to prepare an allowable increase amount as map data in advance, a large-capacity memory is required in a controller that performs arithmetic processing, which also leads to an increase in cost. Furthermore, the above-mentioned Japanese Patent Publication No. 5-3449
In No. 8, when the accelerator opening is suddenly changed and the accelerator opening is stabilized after entering the acceleration (deceleration) state, the allowable increase is calculated from the accelerator change every time the target injection amount is calculated. The permissible increase / decrease amount greatly changes at the boundary between the time when the accelerator suddenly changes and the time when the accelerator stabilizes (in the same transient state).

That is, the target injection amount is increased by a relatively large width immediately after entering the transient state, but thereafter, the increase width suddenly becomes minimum and changes so as to approach the basic target injection amount with the minimum width. I do. As a result, there is a problem that a feeling of acceleration (deceleration) peaks out.

Accordingly, the present invention provides an electronically controlled fuel injection device for a diesel engine that determines a target injection amount based on the operating state of a vehicle, and has a low development cost and a low product cost (EC
M) It is intended to reduce the cost and eliminate the feeling of acceleration / deceleration peaking off when the accelerator opening is suddenly changed.

[0010]

In order to achieve the above object, in an electronic control fuel injection device for a diesel engine according to the present invention, a controller determines a difference between a basic target injection amount and a previous target injection amount. An injection increase / decrease amount is determined by multiplying by a predetermined coefficient, and a value obtained by adding the injection increase / decrease amount to the previous target injection amount is determined as the current target injection amount.

That is, in the present invention, as shown in principle in FIG. 1, at the time of acceleration, the difference between the basic target injection amount Qbase and the previous target injection amount is multiplied by a predetermined coefficient Kacl. To the new target injection quantity Qds
I'm trying to get r. Even during deceleration, the difference between the basic target injection amount Qbase and the previous target injection amount is multiplied by a predetermined coefficient Kdcl, and this is subtracted from the previous target injection amount to obtain a new target injection amount Qdsr. ing. Therefore, the optimum allowable increase / decrease amount is determined in advance for each of the plurality of operation states, and a memory for storing the optimum allowable increase / decrease amount is not required, so that both development and product costs can be reduced.

Further, when the basic target injection amount changes suddenly due to a sudden change in the operating state and the basic target injection amount becomes stable after entering the transient state, the increase / decrease amount gradually decreases each time the target injection amount is calculated. . That is, as shown in FIG. 1, the target injection amount is increased or decreased by a relatively large width immediately after entering the transient state,
After that, it changes so as to smoothly converge to the basic target injection amount. Therefore, the amount of increase / decrease does not suddenly decrease during the acceleration / deceleration damping control, and the feeling of peaking during acceleration / deceleration can be eliminated.

The above-mentioned operating state detecting means can detect the rotational speed and load of the engine as the operating state.

Further, the controller uses a predetermined increase coefficient as the coefficient when the difference is equal to or larger than the acceleration threshold, and uses a predetermined decrease coefficient as the coefficient when the difference is equal to or smaller than the deceleration threshold. When the difference is between the two thresholds, the basic target injection amount can be used as the current target injection amount.

[0015]

FIG. 2 shows an embodiment of an electronically controlled fuel injection device for a diesel engine according to the present invention.
It is a cylinder direct injection engine, and the controller (EC) is controlled by output signals of various sensors provided in the intake system and exhaust system.
M) 2 is a system for performing fuel injection control.

More specifically, an equally-spaced gear 5 partially having a toothless portion 4 fixed to the crankshaft 3 of the engine 1
A rotation speed sensor 6 constituted by an electromagnetic pickup so as to be electromagnetically coupled with the controller 2 detects the rotation speed (NE) of the engine 1 and provides the rotation speed (NE) to the controller 2. An accelerator opening sensor 8 composed of a potentiometer detects the amount of depression of the accelerator pedal 7 (accelerator opening: ACL) and supplies the detected amount to the controller 2. The controller 2 converts the accelerator opening of the analog signal into a digital signal and takes it in. The rotation speed sensor 6 and the accelerator opening sensor 8 provide the engine 1
Of the minimum operation state detecting means.

The operating state detecting means preferably includes an intake pressure sensor 10 provided at a position shown in the drawing so as to detect the intake pressure of the intake pipe 9, and an engine water temperature provided at a head 11 above a cylinder 12 of the engine 1. A water temperature sensor 13 for detection, an intake air temperature sensor 14 for detecting the intake air temperature of the intake pipe 9 and the like are usually provided and connected to the controller 2.

A hydraulically operated unit injector 16 is provided above the cylinder 12 so that fuel is directly injected into the cylinder 12. The injector 16 is connected so that high-pressure oil is supplied from a high-pressure oil pump 18 and low-pressure fuel is supplied from a fuel pump 19 via an oil rail 17 placed beside the cylinder head 11. . This oil pump 18
Is pressure-controlled by the controller 2 via a control valve (RPCV) 19.

That is, a relatively low-pressure fuel is supplied from a fuel pump 19 to a fuel chamber formed inside the injector 16, and this fuel is driven (stroke-driven) by high-pressure oil from an oil pump 18. The fuel is injected at an injection pressure independent of the engine speed by pressurizing with a plunger (not shown). The oil pressure at this time is detected by the sensor 21a, and the oil temperature is detected by the sensor 21b and fed back to the controller 2.

An electromagnetic valve (not shown) is provided in a path for supplying the high-pressure oil of the oil pump 18 from the oil rail 17 to the pressure-increasing plunger pressure receiving surface in the injector 16. The fuel injection is performed by controlling the energization (valve opening) by a control signal from the controller 2.

That is, the controller 2 determines the energizing time (pulse width or duty ratio) to the solenoid valve based on the target injection amount, and energizes the solenoid valve with this pulse width to thereby control the solenoid valve. Control the fuel injection amount. Reference numeral 22 denotes a glow plug for assisting engine start.

An EGR (exhaust gas recirculation) pipe 24 is connected from the exhaust pipe 23 of the engine 1 to the intake pipe 9 to reduce the combustion temperature of the engine 1 by returning a part of the exhaust gas to the intake side. The nitrogen oxides are reduced by lowering them. An EGR valve 25 is provided in the middle of the EGR pipe 24. The valve lift amount of the EGR valve 25 is controlled by a control valve (EVRV) 27 utilizing a negative pressure of a vacuum pump 26, and the lift amount (negative pressure) is detected by a sensor 29 and given to the controller 2. .

Further, an oil temperature sensor 30 provided at a position where an operating oil temperature of an automatic transmission (not shown) can be detected, and a shift position detection provided at a position where a shift position of a shift lever (not shown) can be detected. A switch 31 and a key switch 32 for detecting the position of an ignition key are connected to the controller 2.

For a more detailed description of the fuel injection control system, reference can be made to JP-A-6-511527.

FIG. 3 is a conceptual diagram showing the calculation of the target injection amount by the controller 2. First, the basic target injection amount Qbase is determined from the rotational speed NE detected by the rotational speed sensor 6 and the accelerator opening ACL detected by the accelerator opening sensor 8 with reference to a conventionally known map.

[0026] Next, the manner determined basic target injection quantity Qbase the previous damping control for determining a damping target injection amount Qdmp of acceleration and deceleration by comparing the target injection quantity Qds r bfr (corrected) . Conventionally, the damping target injection amount Qdmp is based on the intake pressure Pb detected by the intake pressure sensor 10, the water temperature Tw detected by the water temperature sensor 13, and the oil pressure and oil temperature detected by the sensors 21a and 21b. Various known corrections (for example, addition correction) are performed to determine the final target injection amount Qdsr. The controller 2 performs such a calculation at a fixed time cycle or a fixed crank angle cycle.

When the predetermined crank angle (BTDC 40 ° CA) before the fuel injection of each engine cylinder is reached, the controller 2 executes an interrupt process to determine the pulse width of the solenoid valve in the injector 16 based on the final target injection amount Qdsr. To determine.

FIG. 4 shows a flowchart of the damping control (correction) shown in FIG. First, calculate the difference ΔQ between the basic target injection quantity Qbase and the previous target injection quantity Qds r bfr obtained from the map of FIG. 3 (step S1). Then, this difference ΔQ is used as an acceleration determination value Δ
Compare with Qacl (step S2).

If the difference .DELTA.Q is larger than the acceleration determination value .DELTA.Qacl, it can be determined that the vehicle is in an acceleration operation state, and the routine proceeds to step S3, where the difference .DELTA.Q is multiplied by a predetermined acceleration damping coefficient Kacl (for example, 0.5). ones and by adding to the previous target injection quantity Qds r bfr, determine the acceleration damping target injection amount Qdmp. By repeating this, FIG.
As shown in (2), the acceleration damping toward the basic target injection amount Qbase is gradually executed.

On the other hand, if it is found in step S2 that the difference ΔQ is smaller than the acceleration judgment value ΔQacl, the process proceeds to step S4, and the difference ΔQ is reduced to the deceleration judgment value ΔQ
Compare with dcl. When the difference ΔQ is smaller than the deceleration determination value ΔQdcl (here, given as a negative value), it can be determined that the vehicle is currently in the deceleration operation state, and the process proceeds to step S5, where a predetermined deceleration damping coefficient Kdcl is added to the difference ΔQ.
(For example, 0.5) is multiplied by the previous target injection amount Qds
The deceleration damping target injection amount Qdmp is obtained by adding to rbfr. By repeating this, the deceleration damping toward the basic target injection amount Qbase is gradually executed as shown in FIG.

When the difference ΔQ is larger than the deceleration determination value ΔQdcl in step S4, it can be determined that the vehicle is not in the acceleration operation state or the deceleration operation state. To end.

By repeating the above calculation routine, the damping control shown in FIG. 1 is realized.

In the above embodiment, the control is performed with the target injection amount. However, it goes without saying that the pulse width (duty ratio) of the command pulse for the solenoid valve in the injector may be corrected.

[0034]

As described above, the electronically controlled fuel injection system for a diesel engine according to the present invention increases or decreases the difference between the basic target injection amount determined from the operating state of the vehicle and the previous target injection amount by a predetermined amount. By multiplying the coefficient to determine the injection increase / decrease amount, and adding the injection increase / decrease amount to the previous target injection amount, the current target injection amount is determined, so that acceleration / deceleration under typical operating conditions is performed. It is sufficient to determine the coefficient, and it is not necessary to obtain the allowable increase / decrease amount itself in advance. Therefore, the development burden is reduced. Further, since the degree of damping changes in accordance with the above difference, it is possible to realize good drivability without feeling the acceleration / deceleration peaking out.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating the principle of an electronically controlled fuel injection device for a diesel engine according to the present invention.

FIG. 2 is a system configuration diagram showing one embodiment of an electronically controlled fuel injection device for a diesel engine according to the present invention.

FIG. 3 is a block diagram conceptually showing the operation of the electronically controlled fuel injection device for a diesel engine according to the present invention.

FIG. 4 is a flowchart of a control program executed by a controller in the electronically controlled fuel injection device for a diesel engine according to the present invention.

[Explanation of symbols]

1 is a diesel engine, 2 is a controller (EC
M), 3 is a crankshaft, 4 is a missing tooth portion, 5 is a gear,
6 is a rotational speed sensor, 7 is an accelerator pedal, 8 is an accelerator opening sensor, 9 is an intake pipe, 10 is an intake pressure sensor, 11
Is a cylinder head, 12 is a cylinder, 13 is a water temperature sensor, 14 is an intake air temperature sensor, 15 is an intake throttle valve,
5a is a throttle valve position sensor, 16 is an injector,
17 is an oil rail, 18 is an oil pump, 19 is a fuel pump, 20 is a control valve, 21a is a hydraulic sensor, 21b is a hydraulic sensor, 22 is a glow plug, 23 is an exhaust pipe, 24
Is an EGR pipe, 25 is an EGR valve, 26 is a vacuum pump, 27
Denotes a negative pressure control valve (EVRV), 29 denotes a negative pressure sensor, 30 denotes an oil temperature sensor of the automatic transmission, 31 denotes a shift position detection switch, and 32 denotes an ignition key switch unit. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (3)

[Claims] 1. An electronically controlled fuel injection system for a diesel engine in which a controller determines a basic target injection amount at regular intervals based on an operation state detected by an operation state detection means of a vehicle. The difference between the amount and the previous target injection amount is multiplied by a predetermined coefficient to determine the injection increase / decrease amount, and the value obtained by adding the injection increase / decrease amount to the previous target injection amount is determined as the current target injection amount. An electronically controlled fuel injection device for a diesel engine. 2. An electronically controlled fuel injection system for a diesel engine according to claim 1, wherein said operating state detecting means detects an engine speed and a load as an operating state. 3. The controller according to claim 1, wherein the controller uses a predetermined increase coefficient as the coefficient when the difference is equal to or larger than the acceleration threshold, and uses a predetermined decrease coefficient as the coefficient when the difference is equal to or smaller than the deceleration threshold. An electronically controlled fuel injection device for a diesel engine, wherein the basic target injection amount is used as a current target injection amount when the difference is between the two threshold values.