JPH0413534B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel injection control method for an electronically controlled diesel engine, and more particularly to a fuel injection control method for an electronically controlled diesel engine that is optimal for improving drivability during acceleration.

The injection quantity Q characteristic with respect to the engine speed Ne of a diesel engine changes depending on the accelerator opening as shown in Figure 1, but as is clear from the figure, when the accelerator is suddenly depressed, the fuel injection quantity changes rapidly. Changes to In particular, in manual transmission vehicles, where the driving force of the engine is directly transmitted to the wheels, acceleration shock occurs because the fuel injection amount changes rapidly in response to sudden accelerator pedal depression. There is no problem if you press the accelerator appropriately according to the gear position, but if you are not familiar with the car or if you make a driving mistake and suddenly press the accelerator in a low gear position, acceleration shock will be unavoidable and it will be extremely difficult to drive. I was having a bad time.

An object of the present invention is to provide a fuel injection control method for an electronically controlled diesel engine that reduces acceleration shock during acceleration in a manual transmission (M/T) vehicle.

The present invention is designed to gradually increase the amount of fuel from at least a predetermined amount before the target value of the fuel injection charge to the target value without abruptly changing the fuel injection amount in response to a sudden change in accelerator depression. be. Specifically, the injection amount may be gradually increased to the target value from the time of acceleration, or the injection amount may be increased all at once to a certain amount at the time of acceleration, and then gradually increased to the target value. The latter is particularly suitable when the fuel injection amount command value increases rapidly. Moreover, each of the above-mentioned controls may be changed according to changes in engine speed, vehicle speed, accelerator opening, etc.

FIG. 2 shows a fuel injection pump and a control device suitable for applying the present invention.

The fuel injection pump 1 includes a drive shaft 11 driven by an engine, a gear 12 and a roller 13 provided at the end of the drive shaft,
A cam plate 1 loosely connected to the roller 13
4. A pump having a spill port 50 therein and coupled to the plate 14 for sending fuel to the injection nozzle 2 of the engine; a plunger 15; a fuel pump for sending fuel to the injection nozzle 2 and the timer piston 16; 17. A timer position sensor 18 that electrically detects the position of the timer piston 16, a timing control valve 19 that determines advance angle adjustment, and an electromagnetic pickup sensor as a rotation speed detector that outputs a pulse signal according to the rotation speed of the gear 12. 20, a spill ring 21 that is driven by a linear solenoid to adjust the injection amount; a linear solenoid 2 that drives the spill ring 21;
2. Coil 2 constituting the linear solenoid 22
3, a plunger 24 that drives the spill ring 21, a spill position sensor 25 that detects the amount of movement of the plunger 24, and an FCV 2 that controls on/off the amount of fuel to the pump/plunger 15.
6 (consisting of excitation coil 27 and valve 28),
It consists of a delivery valve 56 and a regulating valve 29 for preventing backflow or dripping of fuel from the pump plunger 15.

The cam plate 14 rotates and reciprocates together with the pump plunger 15. This reciprocating motion is caused by the cam plate 14 riding on the roller 13, which is rotatable but fixed in the axial direction of the shaft. The fuel is distributed by rotating the pump plunger 15. Regarding the adjustment of the injection quantity, the maximum injection quantity is determined by the effective stroke of the pump plunger 15. Excess fuel in the pump is removed from orifice 3.
0 to the pump 17 side. In addition, the linear solenoid 22 in the fuel pump 1 and the FCV
26 is controlled by the control device 3, and for this purpose output signals from various sensors are taken in. That is, the engine rotation speed signal S _N from the electromagnetic pickup sensor 20 and the spill position sensor 25
These are pump-side information and engine-side information of the output signal S _S of . Note that the timer position sensor 18 is used for timing control and is not related to the present invention, so a description thereof will be omitted. Engine side information includes an output signal S _a of the intake air temperature sensor 5 provided in the intake manifold 4, an output signal S _P of the intake pressure sensor 6 also provided in the intake manifold 4, and an output signal of the water temperature sensor 7 that measures the engine cooling water temperature. Accelerator sensor 9 that detects S _W and the amount of depression of accelerator 8
There is an output signal _SACC respectively, but some of this information is also used for air-fuel ratio control. The figure is shown here to show that the control device 3 handles other processes as well as controlling the linear solenoid 22.

FIG. 3 is a detailed block diagram of the control device 3 shown in FIG.

With a central processing unit (CPU) 31 as the core, a read-only memory (ROM) 32 stores processing programs and monitor programs for executing various processes, and temporarily stores calculation contents and output contents of each sensor. A random access memory (RAM) 33 and an input circuit 34 are connected to the CPU 31 via a bus line 35, and have a backup memory for storing calculation contents, setting values, etc. even when the power is turned off.
A so-called microcomputer is configured.
The output devices connected to the CPU 31 and controlled are the linear solenoid 22 and the FCV 26.
The FCV 26 is driven via the drive circuit 36, and the linear solenoid 22 is driven by the D/A converter 3.
7. Driven through each of the servo amplifiers 38 and further through a drive circuit 39. The input/output circuit 34 is for taking in sensor output, and is for receiving sensor output from each sensor 5,
Outputs of 6, 7, 9, 25 (buffers 40, 41,
42, 43, 44) are sequentially or selected by a multiplexer (MPX) 45, converted into a digital signal by an A/D converter 46, and then outputted to the bus line 36. Further, a rotation speed detector 20 for detecting the engine rotation speed is provided, and its output signal is waveform-shaped by a waveform shaping circuit 47 and then sent to the CPU 31.

A clock circuit 47 is provided to send clock pulses to the CPU 31, each input/output circuit 34, the A/D converter 46, and the D/A converter 37.

FIG. 4 is a flowchart showing the processing of the embodiment of the present invention. In this process, the fuel injection amount is increased at once by a fixed amount β at the time of acceleration, and then increased stepwise by an amount α smaller than β up to the target value.

First, in step 101, intake air temperature (THA), engine speed (N _E ), accelerator opening ( _ACCP ), and intake pressure (P _M ) are measured by the intake air temperature sensor 5, electromagnetic pickup sensor 20, accelerator sensor 9, and intake air pressure. Based on the data read from each of the sensors 6, the fuel injection amount Q _I to be injected this time is calculated in step 102.

Upon completion of calculation of the current injection amount Q _I in step 102, the process moves to step 201. step
In step 201, it is determined whether the control based on the increase β has already been performed or not based on whether the flag FLAG is 1 or not. If FLAG is not set, step
Moving on to step 202, compare the difference between the previous fuel injection amount Q _I-1 and the current fuel injection amount Q _I , (Q _I − _{Q I-1} ), and β.
Determine whether acceleration is occurring. That is, if (Q _I −Q _I-1 )>β, it is determined that acceleration is occurring, and if (Q _I −Q _I-1 )<β, it is determined that there is no acceleration. Step if no acceleration
The fuel injection amount calculated in step 102 is injected, but during acceleration, in step 203, the previous injection amount Q _I-1 is added with a constant increase value β (Q _I-1 + β) to the current value Q _I
(β correction value for Q _I in step 102), and at the same time, in step 204, a flag FLAG is set.
The Q _I obtained in step 203 is stored in step 107, and the linear solenoid 22 is driven to perform a predetermined fuel injection. After this, the process is step 101
Returning to step 201, the presence or absence of FLAG is checked (if β is increased, FLAG is naturally set and FLAG = 1), and the process is moved to step 104, where α is increased to the target value. .

In step 104, a predetermined increase step value α according to various engine characteristics is applied to the previous injection amount.
Q _I-1 and this (Q _I-1 + α) is the target injection amount Q _I
It is assumed that the amount of injection (Q′ _I-1 ) is one injection amount that is divided into multiple injections. Then, in step 105, it is determined whether the first increase value exceeds the target value _QI . If Q _I > Q′ _I-1 , the target value has been reached and there is no need to increase the amount further, so move on to the next process, and if Q _I < Q′ _I-1 , increase the amount by α. Execute. If Q _I > Q′ _I-1, proceed to step 106.
Remember Q′ _I-1 as Q _I , and then write Q _I in step 107.
Store it in RAM33 as Q _I-1 . In other words, Q′ _I-1 , which corresponds to one dose of stepwise increase by α, is
Assume that the current fuel injection amount Q _I is,
This is further assumed to be the injection amount Q _I-1 injected one time previously in step 107. Meanwhile, step 105
If Q _I <Q′ _I-1 , then the target value Q _I
Since it is necessary to increase the injection amount by α multiple times until the injection amount reaches the previous injection amount, the process advances to step 107 to memorize only the previous injection amount, and then to step 108.
Q _I is converted into a control output V _spp for the D/A converter 39 and output in step 109 . Based on this control output _Vspp , the linear solenoid 22 moves by a predetermined amount to move the spill ring 21. Note that if it is not acceleration, the process moves from step 202 to step 107 and the subsequent processing is performed.

If (Q _I <Q' _I-1 ) in step 105, the FLAG is reset in step 205 in preparation for the next injection process, and then the process moves to step 107.

According to this embodiment, by increasing the amount of injection at the initial stage, there is an advantage that it is possible to provide a feeling of acceleration while reducing acceleration shock.

In addition, in each of the above embodiments, the amount is increased in stages regardless of the vehicle speed, so when applied to high-speed driving, etc., an acceleration delay occurs, which is inconvenient. Therefore, the vehicle speed may be detected and the stepwise increase may be canceled depending on the vehicle speed, or the number of stages of the stepwise increase may be changed. Similarly, the control mode can be changed depending on the accelerator opening degree in a high engine speed or a high speed range of the shift lever.

As is clear from the above, according to the present invention, acceleration shock can be reduced by providing a step of increasing the fuel injection amount in at least a part of the fuel injection control during acceleration.

[Brief explanation of drawings]

Fig. 1 is an injection characteristic diagram of a diesel engine, Fig. 2 is a configuration diagram of a fuel injection pump and control device suitable for applying the present invention, and Fig. 3 is a detailed block diagram of the control device 3 shown in Fig. 2. , FIG. 4 is a flowchart showing an embodiment of the present invention. 1...Fuel injection pump, 3...Control device, 5...
...Intake temperature sensor, 6...Intake pressure sensor, 9...Accelerator sensor, 15...Pump plunger,
20... Electromagnetic pickup sensor, 21... Spill ring, 22... Linear solenoid, 26...
FCV, 31... central processing unit, 32... ROM,
33... RAM, 34... Input circuit, 35... Bus line, 36... Drive circuit, 37... D/A converter, 38... Servo amplifier, 39... Drive circuit, 40, 41, 42, 43, 44...buffer, 45...multiplexer, 46...A/D converter.

Claims (1)

[Scope of Claims] 1. A fuel injection control method for an electronically controlled diesel engine in which the fuel injection amount in the diesel engine is controlled via an electronically controlled fuel injection pump while calculating the injection amount based on the operating state of each part of the engine. , electronic control characterized in that when an acceleration state is determined, the fuel injection amount is increased by a certain amount at once, and then the amount is increased stepwise to a fuel injection amount target value at a predetermined increase rate smaller than the certain amount. Diesel engine fuel injection control method. 2. The fuel injection control method for an electronically controlled diesel engine according to claim 1, characterized in that the control is canceled and the increase rate is changed depending on the running state or driving state of the vehicle.