JPH063162B2 - Method of controlling injection quantity of electronically controlled diesel engine - Google Patents

Description

Detailed Description of the Invention [Industrial applications]

The present invention relates to a method for controlling an injection amount of an electronically controlled diesel engine, and particularly to at least an engine load and an average engine rotation speed suitable for use in an electronically controlled diesel engine for an automobile equipped with a solenoid valve spill type injection pump. The present invention relates to an improvement in an injection control method for an electronically controlled diesel engine in which the injection end timing is determined based on the number.

[Prior art]

In recent years, with the development of electronic control technology, especially digital control technology, so-called electronically controlled diesel engines, which electronically control injection pumps of diesel engines, have been put into practical use. There are various methods of electronically controlling the injection pump, and one of them is a so-called solenoid valve spill system in which the fuel overflow timing (hereinafter referred to as spill timing) in the injection pump is controlled by a solenoid valve. There is an injection pump. In this electromagnetic valve spill system injection pump, when the fuel injection amount reaches the target value, the spill port is opened by the electromagnetic spill valve to control the fuel injection amount by controlling the end of the pressure feed of the fuel. I am trying. In an electronically controlled diesel engine using such an electromagnetic spill valve type injection pump, as shown in FIG. 6, the fuel injection amount Q is controlled by changing the spill command timing θ _sp for releasing the pressure in the plunger chamber. I am trying to do it.
On the other hand, the spill command timing θ _sp is calculated by, for example, the average engine speed NE and the engine load, for example, the accelerator opening A _ccp , as shown in FIG. 7. Here, the average engine speed NE is calculated as shown in FIG. 8 by the required time between engine rotation pulses (hereinafter referred to as NE pulses) input at each predetermined crank angle. Therefore, the average engine speed NE is calculated once for each injection of each cylinder, that is, 180 ° CA for a four-cylinder engine.
You can do it every time.

[Problems to be Solved by the Invention]

However, the average engine speed N per 180 ° CA
When E is calculated, there is no problem if the engine is in a steady state, but during transition, a difference occurs between the calculated average engine speed NE and the actual average engine speed NE ', so during deceleration, As shown in FIG. 9, the average engine speed NE becomes larger than the actual average engine speed NE ′, and as is apparent from FIG. 7, the spill command timing θ _sp
Is calculated a little, and when the injection amount is insufficient,
It may lead to engine stall. On the contrary, during acceleration, the average engine speed NE becomes smaller than the actual average engine speed NE ', so that as is apparent from FIG. 7, the spill command time θ _sp is calculated to be large and the injection amount is There was a problem that the concentration of exhaust black smoke increased due to excess. In order to solve such a problem, a method of calculating the average engine speed NE immediately before the spill time is conceivable, but the calculation of the average engine speed NE is performed according to the program.
The spill command timing θ _sp changes by about 70 ° CA at the maximum, as can be seen from FIG. 7, whereas the spill command timing θ _sp changes from the calculation of the average engine speed NE, while the spill command timing θ _sp changes every time. In practice, it is impossible to always bring in the calculation of the average engine speed NE immediately before the spill time because there is an irregular time delay for the program to advance by the time. Therefore, conventionally, the average engine speed NE has to be calculated frequently, for example, every 45 ° CA, which is complicated in terms of the program.

[Object of the Invention]

The present invention has been made to solve the above-mentioned conventional problems, and it is possible to calculate the average engine speed with the highest load on a program with a simple program, and to optimize the injection amount even in a transient state. It is an object of the present invention to provide an injection amount control method for an electronically controlled diesel engine, which can be controlled in a controlled manner.

[Means for solving problems]

The present invention relates to an injection amount control method for an electronically controlled diesel engine in which the injection end timing is determined based on at least the engine load and the average engine speed NE _sp for determining the injection end timing. As shown, the average engine speed calculation procedure for calculating the average engine speed NE only once at a fixed timing for each injection of each cylinder, and the previous average obtained in the procedure for calculating the average engine speed. A procedure for calculating a difference DNE between the engine speed NE-1 and the current average engine speed NE, and a procedure for obtaining a correction value Kn that becomes larger as the previous injection end timing is later,
According to the acceleration / deceleration state of the engine rotation based on the difference DNE, the current average engine rotation speed NE is corrected so as to increase during acceleration of the engine rotation and decrease during deceleration of the engine rotation. ,
The larger the correction value Kn, the greater the degree of this correction, and the above-mentioned acceleration / deceleration state is taken into consideration. The average engine speed NE for determining the injection end timing for determining the injection end timing.
_The object is achieved by including a procedure for obtaining _sp . The embodiment of the present invention is also directed to the average engine speed NE.
Is to be calculated only once, 5 to 15 ° CA before the earliest injection end timing in engine control. Further, in the embodiment of the present invention, the correction value Kn is set to the difference D
When the angle from the calculation timing of the average engine speed NE, which is multiplied by NE, to the injection end timing is 0 ° CA, 0,
The correction coefficient Kn is 1 when it is equal to the injection interval of each cylinder.

[Action]

During a transition in which the engine speed rapidly changes, the difference between the calculated average engine speed NE and the actual average engine speed becomes large, and correct control cannot be performed. In order to prevent this, the difference DNE between the previous average engine speed NEi-1 and the current average engine speed NEi is calculated, and the correction value Kn is calculated according to the previous injection end timing, and these difference DNE and Based on the correction value Kn, the average engine speed NE _sp for determining the injection end timing in consideration of the acceleration / deceleration state is obtained. Therefore, the average engine speed NE _ps for determining the injection end timing becomes a value reflecting the acceleration / deceleration state, and the injection amount can be optimally controlled even in the transient state with a simple program. Further, when the timing for calculating the average engine speed NE only once is 5 to 15 ° CA before the earliest injection end timing in engine control, the average engine speed is calculated at the optimum timing. be able to. Further, the correction value Kn is multiplied by the difference DNE, and is 0 when the angle from the calculation timing of the average engine speed NE to the injection end timing is 0 ° CA, and is 1 when it is equal to the injection interval of each cylinder. When the coefficient Kn is used, the average engine speed can be corrected easily and accurately.

【Example】

Hereinafter, an embodiment of an electronically controlled diesel engine for an automobile, in which an injection amount control method according to the present invention is adopted, will be described in detail with reference to the drawings. In this embodiment, as shown in FIG. 2, an intake air temperature sensor 12 is provided downstream of an air cleaner (not shown) for detecting the temperature of intake air. A turbocharger 14 including a turbine 14A that is rotated by the heat energy of the exhaust gas and a compressor 14B that is rotated in conjunction with the turbine 14A is provided downstream of the intake air temperature sensor 12. The upstream side of the turbine 14A of the turbocharger 14 and the downstream side of the compressor 14B are connected to each other via a waste gate valve 15 for preventing an excessive rise in intake pressure. In the venturi 16 downstream of the compressor 14B,
A main intake throttle valve 18 is provided which is configured to rotate in a non-linear manner in conjunction with an accelerator pedal 17 provided in a driver's seat for limiting the flow rate of intake air during idling or the like. An opening degree of the accelerator pedal 17 (hereinafter referred to as an accelerator opening degree) A _ccp is detected by an accelerator position sensor 20. An auxiliary intake throttle valve 22 is provided in parallel with the main intake throttle valve 18, and the opening degree of the auxiliary intake throttle valve 22 is controlled by a diaphragm device 24. The negative pressure generated by the negative pressure pump 26 is supplied to the diaphragm device 24 via a negative pressure switching valve (hereinafter referred to as VSV) 28 or 30. An intake pressure sensor 32 for detecting the pressure of intake air is provided downstream of the intake throttle valves 18, 22. In the cylinder head 10A of the diesel engine 10,
An injection nozzle 34, a glow plug 36, and an ignition timing sensor 38 whose tip faces the engine combustion chamber 10B are provided. Further, the cylinder block 10C of the diesel engine 10 is provided with a water temperature sensor 40 for detecting the engine cooling water temperature. Fuel is pumped from the injection pump 42 to the injection nozzle 34. The injection pump 42 includes a pump drive shaft 42A that is rotated in conjunction with the rotation of the crankshaft of the diesel engine 10, and a feed pump 42B (second) fixed to the pump drive shaft 42A for pressurizing fuel.
(The figure shows a state of being developed by 90 °), a fuel pressure adjusting valve 42C for adjusting the fuel supply pressure, and the pump drive shaft 42
A crank angle reference sensor 44, which is, for example, an electromagnetic pickup, for detecting a crank angle reference position, for example, top dead center (TDC) from the rotational displacement of the pump drive pulley 42D fixed to A, and also fixed to the pump drive shaft 42A. An NE pulse for detecting the engine speed or the like from the rotational displacement of the gear 42E that has been generated, for example, an engine rotation sensor 46 composed of an electromagnetic pickup, a face cam 42F and a plunger 42G are reciprocated, and the timing thereof is changed. Roller ring 42H and a timer piston 42J for changing the rotational position of the roller ring 42H (FIG. 2 shows a 90 ° unfolded state).
And a timing control valve (hereinafter referred to as TCV) 48 for controlling the injection timing by controlling the position of the timer piston 42J, and a fuel escape timing from the plunger 42G via the spill port 42K. The electromagnetic spill valve 50 for controlling the fuel injection amount and the fuel cut valve 52 for cutting the fuel
And a delivery valve 42L for preventing backflow of fuel and backward drip. A glow current is supplied to the glow plug 36 via a glow relay 37. The intake temperature sensor 12, the accelerator position sensor 20, the intake pressure sensor 32, the ignition timing sensor 38, the water temperature sensor 40,
Crank angle reference sensor 44, engine rotation sensor 46,
A glow current sensor 54 for detecting a glow current flowing through the glow plug 36, a key switch, an air conditioner switch, a neutral safety switch output, a vehicle speed signal, etc. are input to an electronic control unit (hereinafter referred to as ECU) 56 and processed. By the output of the ECU 56, the VSV 28, 30, the glow relay 37, the TCV 48,
The electromagnetic spill valve 50, the fuel cut valve 52, etc. are controlled. As shown in detail in FIG. 3, the ECU 56 includes a central processing unit (hereinafter referred to as a CPU) 56A for performing various arithmetic processes, and a read-only memory (hereinafter, referred to as a CPU) for storing control programs and various data. 56B, a random access memory (hereinafter referred to as RAM) 56C for temporarily storing operation data and the like in the CPU 56A, a clock 56D for generating a clock signal, and a buffer 56E. Output of the water temperature sensor 40, output of the intake temperature sensor 12 input via a buffer 56F, output of the intake pressure sensor 32 input via a buffer 56G, and accelerator position sensor 20 input via a buffer 56H.
Multiplexer (hereinafter MP
56K, an analog-digital converter (hereinafter referred to as an A / D converter) 56L for converting an analog signal of the MPX 56K output to a digital signal, and an output of the A / D converter 56L to the CPU 56A. Via the input / output port 56M for taking in the input signal, the starter signal input via the buffer 56N, the air conditioner signal input via the buffer 56P, the torque converter signal input via the buffer 56Q, and the waveform shaping circuit 56R. I / O port 56S for taking in the output of the ignition timing sensor 38 and the like input to the CPU 56A, and waveform shaping of the output of the ignition timing sensor 38 to input interrupt terminal IC of the CPU 56A.
The waveform shaping circuit 56R for directly capturing into AP2,
A waveform shaping circuit 56T for waveform-shaping the output of the crank angle reference sensor 44 and directly fetching it into the same input interrupt terminal ICAP2 of the CPU 56A, and a waveform shaping of the output of the engine rotation sensor 46 to generate the NE pulse as the C pulse.
A waveform shaping circuit 56U for directly fetching into the PU 56A,
A drive circuit 56V for driving the electromagnetic spill valve 50 according to the calculation result of the CPU 56A, and the CPU 5
A drive circuit 56W for driving the TCV 48 according to the calculation result of 6A, and a drive circuit 5 for driving the fuel cut valve 52 according to the calculation result of the CPU 56A.
6X, and a common bus 56Y for connecting the respective constituent devices to transfer data and instructions. Here, the ignition signal output from the waveform shaping circuit 56R is
The input to the input interrupt terminal ICAP2 of the PU 56A as well as to the input / output port 56S is for distinguishing from the reference position signal of the waveform shaping circuit 56T output to the same input interrupt terminal ICAP2. The operation of the embodiment will be described below. The calculation of the spill command timing θ _sp in this embodiment is executed according to the flowchart shown in FIG. That is, first, at step 110, since it is, for example, the NE pulse (CNE = 0 in the embodiment) immediately before the smallest spill command timing θ _{sp in} engine control, this is the timing for calculating the average engine speed NE. Or not. If the determination result is positive, the process proceeds to step 112, and the average engine speed NE is calculated from the time required for 180 ° CA. Next, the routine proceeds to step 114, where the difference DNE between the average engine speed NE calculated this time and the previous average engine speed NE is calculated and stored. Next, the routine proceeds to step 116, where it is stored in the ROM 56B in advance according to the value of the spill command timing θ _sp calculated previously.
For example, using the relationship shown in FIG. 5, the correction coefficient Kn
Ask for. Next, the routine proceeds to step 118, where the difference DN is added to the average engine speed NE calculated this time as shown in the following equation.
The average engine speed NE for determining the spill timing, which is obtained by adding E multiplied by the correction coefficient Kn and adding the acceleration / deceleration state.
ask for _sp . NE _sp ← NE + Kn × DNE (1) Next, the routine proceeds to step 120, where the seventh engine speed is calculated according to the determined average engine speed NE _sp and the accelerator opening A _ccp detected by the accelerator position sensor 20. The spill command timing θ _sp is calculated using the relationship shown in the figure. According to the present embodiment, during deceleration, the difference DNE becomes negative and the spill command timing determination average engine speed NE _sp becomes greater than the average engine speed NE, so the spill command timing θ _sp
Is increased, and the shortage of the injection amount during deceleration can be resolved. Conversely, during acceleration, on the contrary, the difference DNE becomes positive and the spill command timing determination average engine speed NE _sp becomes greater than the average engine speed NE, so the spill command timing θ _sp becomes smaller and the exhaust gas during acceleration The increase of black smoke can be suppressed. In the present embodiment, the timing at which the average engine speed NE is calculated only once is the pulse immediately before the earliest spill command timing in engine control, so the average engine speed NE is calculated at an appropriate timing. can do. The timing for calculating the average engine speed NE only once is not limited to this. Further, in this embodiment, the average engine speed NE obtained by the difference DNE between the previous average engine speed and the current average engine speed is determined according to the previous spill command timing θ _sp.
The angle from the calculation timing to the spill command time is 0 °
Since the average engine speed NE of this time is corrected by multiplying the correction coefficient Kn that becomes 0 when CA is 0 and 1 when it is equal to the injection interval (180 ° CA) of each cylinder, it is for determining the spill command timing. Average engine speed NE _sp
Can be obtained easily and accurately. The method of correcting the average engine speed NE according to the difference DNE and the previous spill command time is not limited to this. In the above-described embodiment, the present invention is applied to the electronically controlled diesel engine for automobiles with a turbocharger, in which the fuel injection amount is controlled by the electromagnetic spill valve 50, but the scope of application of the present invention is this. However, the present invention is not limited to the above, and is obviously applicable to a general diesel engine in which the injection end timing is controlled by a fuel injection amount control actuator other than the electromagnetic spill valve.

【The invention's effect】

As described above, according to the present invention, the injection amount can be optimally controlled even in the transient state with the average engine speed calculated for each injection of each cylinder. Therefore, the logic for calculating the average engine speed, which has the highest load on the program, can be greatly simplified. Further, there is an excellent effect that it is possible to prevent an insufficient injection amount during deceleration and an increase in exhaust black smoke during acceleration.

[Brief description of drawings]

FIG. 1 is a flow chart showing the gist of an injection amount control method for an electronically controlled diesel engine according to the present invention, and FIG. 2 shows the overall configuration of an embodiment of an electronically controlled diesel engine for an automobile to which the present invention is adopted, A sectional view including a partial block diagram, FIG. 3 is a block diagram showing the configuration of the electronic control unit used in the above embodiment, and FIG. 4 is the same.
FIG. 5 is a flow chart showing a routine for calculating the spill designation time, and FIG. 5 is a diagram showing an example of the relationship between the previous spill command timing and the correction coefficient, which is used in the routine.
FIG. 7 is a diagram showing an example of the relationship between the spill command timing and the plunger lift, that is, the injection amount. FIG. 7 is a diagram showing an example of the relationship between the average engine speed and the accelerator opening and the spill command timing. FIG. 9 is a diagram showing a method of calculating an average engine revolution speed from an engine revolution pulse, and FIG. 9 is a diagram showing an example of a relationship between an average engine revolution speed during transition (during deceleration) and an actual average engine revolution speed. Is. 10 ... Diesel engine, 20 ... Accelerator position sensor, _Accp ... Accelerator opening degree, 42 ... Injection pump, 46 ... Engine rotation sensor, 50 ... Electromagnetic spill valve, 56 ... Electronic control unit (ECU), NE ... Average engine speed , DNE ... difference between previous and current average engine speed, K _n ... correction coefficient, NE _sp ... average engine speed for determining spill command timing, θ _sp ... spill command timing, Q ... injection amount.

Claims (3)

[Claims] 1. An injection amount control method for an electronically controlled diesel engine, wherein an injection end timing is determined based on at least an engine load and an average engine speed NE _sp for determining an injection end timing. , An average engine speed NE calculation procedure for calculating the average engine speed NE only once at a fixed timing each time, and the previous average engine speed NEi-1 and the current engine speed NEi-1 obtained in the average engine speed calculation procedure. The procedure of calculating the difference DNE from the average engine speed NEi, the procedure of obtaining a correction value Kn that becomes larger as the previous injection end timing is later, and the engine speed acceleration / deceleration state based on the difference DNE Correct the average engine speed NE this time so that it increases during acceleration of rotation and decreases during deceleration of engine rotation. At this time,
The larger the correction value Kn , the greater the degree of this correction, and the above-mentioned acceleration / deceleration state is taken into consideration. The average engine speed NE for determining the injection end timing for determining the injection end timing.
An injection amount control method for an electronically controlled diesel engine, characterized by including a procedure for obtaining _sp . 2. The invention according to claim 1, wherein the timing for calculating the average engine speed NE only once is 5 to 15 ° CA before the earliest injection end timing in engine control.
An injection amount control method for an electronically controlled diesel engine according to the item. 3. The correction Kn is 0 when the angle from the calculation timing of the average engine speed NE to the injection end timing multiplied by the difference DNE is 0 ° CA, and 1 when it is equal to the injection interval of each cylinder. The injection amount control method for an electronically controlled diesel engine according to claim 1, wherein the correction coefficient Kn is