JPH11236844A - Electronic control fuel injection device for diesel engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To dissolve an idling feeling generated at the quick speed reduction time by making a prescribed injection amount a this time target injection amount when a prior target injection amount exceeds the prescribed injection amount and making a value reduced with the prior target injection amount by a prescribed reduction width this time target injection amount at the prescribed injection amount or less time, at the speed reduction time of a vehicle. SOLUTION: At the running time of a vehicle, when the sudden speed reduction operation of an engine is detected in a controller 2, the prior injection amount Qi-1 is compared with a pre-determined prescribed injection amount QTO and when it is Qi-1 >QTO, the prescribed injection amount QTO is decided as a new target injection amount. While, when it is Qi-1 <QTO, the injection amount reduced with the prior injection amount Qi-1 by a prescribed reduction width β is decided as a new target injection amount Qi . In other words, when prior injection amount Qi-1 -prescribed injection amount QTO=α is big, the prior injection Qi-1 is reduced to the prescribed injection amount QTO at one stroke and thereafter, the idling feeling is dissolved by reducing the prior injection amount Qi-1 by the target injection amount Qi reduced by the prescribed reduction width β.

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 rapid deceleration operation from the engine driving state, the accelerator opening rapidly changes, so that the basic target injection amount and the final target injection amount sharply decrease. Is generated. In order to prevent this, a control method (damping control) for gradually reducing the target injection amount by a preset optimum allowable increase / decrease amount is disclosed in Japanese Patent Publication No. 5-75907.

[0004] Further, Japanese Patent No. 25,254 discloses a control for changing the amount of reduction of the target injection amount according to whether the previous injection amount during deceleration is equal to or larger than the no-load (no-load) injection amount Q _T0 .
76183. That is, in this patent, as shown in FIG. 1A, when the relationship of the previous injection amount Q _i-1 > the no _- load injection amount Q _T0 is satisfied, for example, when the engine is rapidly decelerated from the driving state, a large reduction amount “Δ3” To eliminate the feeling of idle running, and conversely, the previous injection amount Q _i-1 at the time of deceleration from the engine braking state, etc.
<When the relationship of the no-load injection amount Q _T0 is established, the control is performed so as to eliminate the deceleration shock and reach the current target injection amount Q _i by setting the small reduction amount “Δ0.7”.

[0005]

[Problems to be solved by the invention] Japanese Patent Publication No. 5-75907
In the conventional damping control represented by the above, various operating conditions (rotational speed, accelerator opening change, water temperature, vehicle speed, etc.)
Each time, the optimal allowable increase / decrease must be set in advance,
A great deal of effort (cost) is required for development including experiments.
Furthermore, since the allowable increase / decrease amount is provided as map data, a large-capacity memory is required in the controller, which also leads to an increase in cost.

In Japanese Patent No. 2576183, the amount of reduction is changed with the no-load injection amount as a boundary. However, since each amount of reduction is predetermined, the previous injection amount is much larger than the no-load injection amount. When the vehicle decelerates from the state, a feeling of idle running (a hatched portion in FIG. 1A) still occurs.

Further, when decelerating from the no-load injection amount or more, as shown in FIG. 5, the amount is reduced across the no-load injection amount Q _T0 , but depending on the previous injection amount Q _{i- 1 at} this time, , The initial loss ranges below the no-load injection amount Q _T0 are γ and δ, which are different from each other,
The feeling when the engine brake starts to be effective is not constant, giving the driver a sense of incompatibility.

Therefore, the present invention provides an electronically controlled fuel injection device for a diesel engine in which a controller determines a basic target injection amount in a fixed cycle based on the driving state detected by the driving state detecting means of the vehicle. The purpose of the present invention is to eliminate the feeling of idling caused when the vehicle decelerates, and to improve the feeling when the engine brake starts to work.

[0009]

In order to achieve the above object, an electronically controlled fuel injection device for a diesel engine according to the present invention comprises a controller which controls a vehicle to decelerate from an operating state (such as the engine speed and load) of the vehicle. When the previous target injection amount exceeds the predetermined injection amount in the deceleration state, the predetermined injection amount is determined as the current target injection amount, and the previous target injection amount is equal to or less than the predetermined injection amount. In the case of, a value obtained by reducing the previous target injection amount by a predetermined reduction width is determined as the current target injection amount.

That is, in the present invention, as shown in principle in FIG. 1 (2), when the previous injection amount Q _i-1 > the predetermined injection amount Q _T0 at the time of rapid deceleration from the engine driving state, the the predetermined injection amount Q _T0 as a new target injection amount, when a previous injection amount Q _i-1 <predetermined injection amount Q _{T 0} is new and reduced the previous injection amount Q _i-1 at a predetermined reduced width β It is set to be obtained, such target injection amount Q _i.

In this manner, when the previous injection amount Q _{i-1 -the} predetermined injection amount Q _T0 = α is large, the previous injection amount Q _i-1 is reduced to the predetermined injection amount Q _{T0 at} once, and thereafter, the previous injection amount Q _i0 is reduced. Since the quantity Q _i-1 <the predetermined injection quantity Q _T0 , the previous injection quantity Q _i-1 can be reduced by the predetermined reduction width β to obtain a new target injection quantity Q _i . No. 25761 shown above.
The feeling of idling like No. 83 can be eliminated.

Further, the predetermined amount of decrease when the previous injection amount is less than the predetermined injection amount is obtained by multiplying the difference between the basic target injection amount and the previous injection amount by a predetermined coefficient. If a new target injection amount is obtained by subtraction, an optimum allowable increase / decrease amount may be obtained in advance for each of various operation states as in Japanese Patent Publication No. 5-75907, or a memory for storing the same. Is also unnecessary, and both development and product costs can be kept low.

In addition, since the initial decrease amount in the region below the predetermined injection amount changes in correlation with the parameter (basic target injection amount) representing the degree of deceleration originally requested by the driver, FIG. The state of the prior art as described above can be avoided, and the deceleration feeling when the engine brake enters is extremely good. The controller can determine the deceleration state based on whether or not the difference between the basic target injection amount and the previous target injection amount is equal to or smaller than a predetermined deceleration constant.

Here, the above-mentioned predetermined injection amount Q _T0 is desirably a no-load injection amount that changes according to an operating state such as a rotation speed. However, in order to simplify control logic, the predetermined injection amount Q _T0 can be substituted for the no-load injection amount. It may be a fixed value.

[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 coolant temperature provided at a head 11 above a cylinder 12 of the engine 1. A water temperature sensor 13 for detecting the air temperature, 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. . The high-pressure oil 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, the difference ΔQ is compared with the acceleration determination value ΔQacl (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, the acceleration damping toward the basic target injection amount Qbase when the engine is in the accelerated state is gradually executed.

The above-described acceleration damping control is given only as an example, and various other known control methods may be used.

On the other hand, if it is found in step S2 that the difference ΔQ is smaller than the acceleration determination value ΔQacl, the process proceeds to step S4, and the difference ΔQ is reduced to
Compare with dcl (here a negative value). When the difference ΔQ is smaller than the deceleration determination value ΔQdcl may determine that the current deceleration operating state, the routine proceeds to step S5, further comparing the previous target injection quantity Qds r bfr a predetermined injection quantity Qdcl.

[0032] As a result, the process proceeds to step S6 when it is found that the previous target injection quantity Qds r bfr ≦ predetermined injection amount Qdcl, multiplied by a predetermined deceleration damping factor Kdcl (e.g. 0.5) to the difference ΔQ (since ΔQ minus values actually subtraction) added to the previous target injection quantity Qds r bfr things to determine the deceleration for damping target injection amount Qdmp.

If the difference ΔQ is larger than the deceleration determination value ΔQdcl in step S4, the process proceeds to step S7, and the basic target injection amount Qbase is set to the damping target injection amount Qdmp. In step S5, the previous target injection amount Qds
When it is determined that rbfr> the predetermined injection amount Qdcl, the process proceeds to step S8, and the predetermined injection amount Qdcl is ended as the damping target injection amount Qdmp. By repeating the above calculation routine, deceleration damping control toward the basic target injection amount can be realized as shown in FIG.

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.

[0036]

As described above, the electronically controlled fuel injection system for a diesel engine according to the present invention determines the deceleration state from the operating state, and when the deceleration state is reached, the previous target injection amount is determined by the predetermined injection amount. When the predetermined injection amount is greater than the predetermined target injection amount, the predetermined target injection amount is determined to be the current target injection amount. Since the injection amount is determined, a desirable deceleration state that is not too abrupt can be obtained, so that the feeling of idling can be eliminated. Further, since the fuel injection amount does not decrease over the predetermined injection amount, the user does not feel uncomfortable when starting the engine braking.

[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 a conventional example and 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.

FIG. 5 is a principle diagram for explaining a disadvantage of a conventional example.

[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 pressure sensor, 21b is an oil temperature 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.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Tadashi Uchiyama, Inventor 8, Fujisawa-shi, Kanagawa Prefecture Isuzu Motors Fujisawa Plant

Claims (5)

[Claims] 1. An electronically controlled fuel injection device 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. Determine the deceleration state,
In the deceleration state, when the previous target injection amount exceeds a predetermined injection amount, the predetermined injection amount is determined as the current target injection amount, and when the previous target injection amount is equal to or less than the predetermined injection amount, the previous injection amount is determined. An electronically controlled fuel injection device for a diesel engine, characterized in that a value obtained by reducing the target injection amount by a predetermined reduction width is determined as a current target injection amount. 2. The diesel engine according to claim 1, wherein the controller sets a value obtained by multiplying a difference between the basic target injection amount and a previous target injection amount by a predetermined reduction coefficient as the predetermined reduction amount. Electronically controlled fuel injector for the engine. 3. The controller according to claim 1, wherein the controller determines the deceleration state based on whether a difference between the basic target injection amount and a previous target injection amount is equal to or smaller than a predetermined deceleration constant. Electronically controlled fuel injection device for diesel engines. 4. An electronically controlled fuel injection device for a diesel engine according to claim 1, wherein said predetermined injection amount is a no-load injection amount. 5. 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.