JPH0718377B2 - 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 suitable for use in an electronically controlled diesel engine for an automobile, when electronically controlling an injection amount according to an engine operating state, at the time of starting, The present invention relates to an improvement in an injection amount control method for an electronically controlled diesel engine that commands an injection amount at startup that is determined by an engine temperature and an accelerator opening.

[Prior art]

In the so-called electronically controlled diesel engine, which is designed to electronically control the injection amount according to the engine operating state,
Conventionally, at the time of low temperature starting, if the engine cooling water temperature and the accelerator opening are constant, an almost constant starting injection amount is commanded.

[Problems to be Solved by the Invention]

However, diesel engines rely on self-ignition. Therefore, if a misfire occurs in a specific cylinder due to spray variation, glow temperature decrease, eddy current variation, etc. at low temperature startup, a large amount of unburned fuel remains in the combustion chamber, so the same is reapplied to that cylinder next time. When a large amount of injection is injected, the glow plug is significantly cooled, and it becomes more difficult to ignite, and there is a problem that misfire of the same cylinder is repeated several times and startability is significantly deteriorated. The present invention has been made to solve the above-mentioned problems with the conventional one, and it is an injection amount control method for an electronically controlled diesel engine capable of improving self-ignitability of a cylinder in which misfire has occurred and improving cold startability. The purpose is to provide.

[Means for solving problems]

The present invention, when electronically controlling the injection amount according to the engine operating state, at the time of starting, in the injection amount control method of the electronically controlled diesel engine for instructing the starting injection amount determined by the engine temperature and the accelerator opening degree, As shown in the outline of FIG. 1, a procedure for detecting a starting state, a procedure for detecting a misfire state from the engine rotation state at the time of starting, and identifying a cylinder in which a misfire has occurred, and a procedure for detecting a misfire state The above-described object is achieved by including a procedure of reducing the injection amount of the misfiring cylinder next time from the injection amount at the time of starting. Further, the embodiment of the present invention, the misfire state, 90% after top dead center
This is detected because the predetermined crank angle rotation time in the vicinity of ° C A (crank angle) is greater than or equal to the predetermined magnification as compared with the predetermined crank angle rotation time in the vicinity of the immediately preceding top dead center. In another embodiment of the present invention, the misfire state is detected because the average engine speed in the vicinity of 90 ° C after top dead center is smaller than the immediately preceding average engine speed. is there.

[Action]

The present invention electronically controls the injection amount according to the engine operating state, and at the time of starting, when instructing the starting injection amount that is determined by the engine temperature and the accelerator opening degree, at the time of starting,
When the misfire state is detected from the engine rotation state, the cylinder in which the misfire has occurred is specified, and the injection amount of the next misfire cylinder is reduced from the injection amount at startup. Therefore, the amount of fuel in the cylinder where the misfire has occurred is reduced, and the self-ignitability of the cylinder can be secured. Therefore, it is possible to prevent repeated misfires in the same cylinder and improve the low temperature startability. Further, the misfire state is detected because the predetermined crank angle rotation required time near 90 ° C. after top dead center is more than the predetermined magnification as compared with the predetermined crank angle rotation required time immediately before the top dead center. In the case of, the misfire state can be detected quickly and accurately. Further, when the misfire state is detected because the average engine speed in the vicinity of 90 ° A after top dead center is smaller than the immediately preceding average engine speed, the misfire state is easily detected. be able to.

【Example】

An embodiment of an electronically controlled diesel engine for a vehicle, in which an injection amount control method according to the present invention is adopted, will be described in detail below with reference to the drawings. In this embodiment, as shown in FIG. 2, an intake air temperature sensor 12 is provided downstream of the air cleaner 11 for detecting the temperature of intake air. Downstream of the intake air temperature sensor 12, a turbine rotated by the heat energy of exhaust gas.
The turbocharger 14 is provided with 14A and a compressor 14B that is rotated in conjunction with the turbine 14A.
The upstream side of the turbine 14A of the turbocharger 14 and the downstream side of the compressor 14B are communicated with each other through a waste gate valve 15 for preventing an excessive rise in intake pressure. The bench lily 16 on the downstream side of the compressor 14B has a main intake throttle valve that is configured to rotate in a non-linear manner in conjunction with an accelerator pedal 17 arranged in the driver's seat for limiting the flow rate of intake air during idling. Eighteen are equipped. Opening of the accelerator pedal 17 (hereinafter referred to as accelerator opening)
Accp is detected by the accelerator 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 a diaphragm device.
Controlled by 24. Negative pressure generated by a negative pressure pump (not shown) 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. The cylinder head 10A of the diesel engine 10 has an injection nozzle 3 with its tip facing the engine fuel chamber 10B.
4, a glow plug 36 and an ignition sensor 38 are provided. Also, the cylinder block 10C of the diesel engine 10
There is a water temperature sensor 40 for detecting the engine cooling water temperature.
Is provided. 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 rotation of a crank shaft (not shown) of the diesel engine 10, and a feed pump 42B that is fixed to the pump drive shaft 42A and pressurizes fuel. (Fig. 2 shows a 90 ° unfolded state), the fuel pressure adjusting valve 42C for adjusting the fuel supply pressure, and the rotational displacement of the pump drive pulley 42D fixed to the pump drive shaft 42A from the crank angle of the engine. A crank angle sensor 44 made of, for example, an electromagnetic pick-up for detecting a reference position, for example, top dead center (TDC), and an engine rotation pulser fixed to the pump drive shaft 42A (hereinafter N
An engine rotation sensor (hereinafter referred to as NE sensor) 46, which is fixed to the roller ring 42H and is composed of, for example, an electromagnetic pick-up, for detecting the engine rotation angle and the tooth-missing position from the rotational displacement of 42E. Face scum
A roller ring 42H for reciprocating the 42F and the plunger 42G and changing the timing thereof, and a timer piston 42J for changing the rotational position of the roller ring 42H.
(Fig. 2 shows a state of 90 ° unfolding) 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 an electromagnetic spill valve (hereinafter referred to as SPV) 50 for controlling the fuel injection amount by changing the fuel escape timing from the plunger 42G via the spill port 42K,
Fuel cut valve (hereinafter FC
(Referred to as V) 52 and a delivery valve 42L for preventing backflow of fuel and backward drip. As shown in detail in FIG. 3, the NE pulsar 42E has a gear shape in which teeth 42E1 for pulse transmission on the outer circumference are provided with toothless teeth 42E2 in accordance with the number of cylinders. Intake temperature sensor 12, accelerator sensor 20, intake pressure sensor
32, ignition sensor 38, water temperature sensor 40, crank angle sensor 4
4. The NE sensor 46, key switch, air conditioner switch, neutral safety switch output, vehicle speed signal, etc. are input to an electronic control unit (hereinafter referred to as ECU) 56 for processing, and by the output of the ECU 56, VSV28, 30, TC
V48, SPV50, FCV52, etc. are controlled. As shown in detail in FIG. 4, the ECU 56 has a central processing unit (hereinafter referred to as CPU) 5 for performing various arithmetic processes.
6A, a read-only memory (hereinafter referred to as ROM) 56B for storing a control program, various data, and the like, and a random access memory (hereinafter referred to as RAM) for temporarily storing operation data and the like in the CPU 56A. ) 56C
, A clock 56D that generates a clock signal, and a buffer 5
Output of the water temperature sensor 40 input via 6E, buffer
The intake air temperature sensor 12 output input via 56F, the intake pressure sensor 32 output input via a buffer 56G,
The accelerator sensor 20 input via the buffer 56H
Multiplexer for sequentially capturing outputs (hereinafter MPX
56K, an analog-digital converter (hereinafter, referred to as an A / D converter) 56L for converting an analog signal of the MPX56K output to a digital signal, and the A / D converter 56L output to the CPU 56A. Input / output port 56M for capturing, starter signal input via buffer 56N, air conditioner signal input from air conditioner via buffer 56P, torque converter signal input from automatic transmission via buffer 56Q , An input / output port 56S for taking in the output of the ignition sensor 38 or the like input via the waveform shaping circuit 56R to the CPU 56A
, The waveform shaping circuit 56R for shaping the output of the ignition sensor 38 directly into the output interrupt terminal ICAP2 of the CPU 56A, and the same input interrupt terminal of the CPU 56A for shaping the output of the crank angle sensor 44. A waveform shaping circuit 56T for directly fetching into the ICAP2, a waveform shaping circuit 56U for directly shaping the engine rotation (NE) signal of the NE sensor 46 output into the CPU 56A, and a calculation result of the CPU 56A. Drive circuit 56V for driving the SPV50 and the CP
A drive circuit 56W for driving the TCV48 according to the calculation result of U56A, and the FCV52 according to the calculation result of the CPU56A.
A drive circuit 56X for driving the device and a common bus 56 for connecting between the respective constituent devices and transferring data and instructions
It consists of Y and. Here, the ignition signal of the waveform shaping circuit 56R output is
Not only input interrupt pin ICAP2 of A, but also input / output port 56S
Is also input to the reference input signal of the waveform shaping circuit 56T input to the same input interrupt terminal ICAP2. The operation of the embodiment will be described below. The injection amount control at the time of starting in this embodiment is executed according to the flow chart as shown in FIG. That is, the NE sensor
46, except for the missing tooth position, the specified crank angle, for example 11.2
The routine is started in synchronization with the NE signal as shown in FIG. 6, which is input at every 5 ° C., and at step 110, the difference between the current start time CAPT and the previous start time BCAPT is calculated as shown in the following equation. Is stored in the NE pulse interval TNINT and step 1
At 12, the next startup time CAPT is set to the previous startup time in preparation for the next time.
BCAPT. TNINT ← CAPT-BCAPT (1) Next, in step 114, the counter CNIRQ counting the NE pulse number is updated as shown in FIG. Next, the routine proceeds to step 116, where it is judged whether or not the NE pulse number CNIRQ is zero indicating immediately after the tooth-missing position. If it is zero, the counter i counting the number of cylinders i at step 118 is set to 0 → 1 →
Update in the order of 2 → 3 → 0 (in case of 4-cylinder engine). After the completion of step 118 or if the result of the determination in step 116 is negative, the process proceeds to step 120, where the NE pulse number CNI
It is determined whether RQ is a predetermined value, for example, 9. If the result of the determination is positive, the routine proceeds to step 122, where the engine water temperature and the engine speed NE are calculated from the engine water temperature and the engine speed NE using the relationship shown in FIG. Calculated injection quantity at startup (spill angle) Qs
The cylinder starting correction amount Qsta (i + 1) of the next cylinder is subtracted from ta to obtain the final starting injection amount Qsta '. Qsta '← Qsta-Qsta (i + 1) (2) Therefore, the cylinder start correction amount Qsta i this time is the injection amount at start.
If 0.4 times Qsta, the final starting injection amount Qst
a'is reduced to 0.6 times the starting injection amount Qsta. After the end of step 122, the routine proceeds to step 124, where the cylinder start correction amount Qsta i for this time is initialized to zero. Next, in step 126, it is determined whether the NE pulse number CNIRQ is a set value near TDC, for example, 5. If the determination result is positive, the NE pulse interval TNINT of this time is set to the TDC vicinity NE pulse interval TNINTi for determining the misfire state in step 128. After the end of step 128, or if the result of the determination in step 126 above is negative, the procedure proceeds to step 130, where the NE pulse number CNI
It is determined whether or not RQ is a set value in the vicinity of 90 ° C after top dead center (ATDC), for example, 13. If the judgment result is positive,
In step 132, it is determined from the starter signal and the average engine speed, for example, whether the engine is in the starting state (STA MODE). If the determination result is positive, the process proceeds to step 134, and the NE pulse interval TNINT of this time, that is, ATDC 90 ° C near A N
It is determined whether or not the E pulse interval is a set multiple of the immediately preceding TDC vicinity NE pulse interval TNINTi, for example, 0.9 times or more. If the judgment result is positive, it is judged as a misfire state, and the step
In 136, set the start correction amount Qsta i for each cylinder to the start injection amount Q
Store the set times of sta, for example 0.4 times. On the other hand, if the result of the determination at the preceding step 130, 132, or 134 is negative, the cylinder-by-cylinder starting correction amount Qsta i is left at zero. Here, the misfire condition is determined from the ratio of the NE pulse interval near TDC and the NE pulse interval near ATDC 90 ° C A. The instantaneous engine speed at the start is normally as shown by the solid line A as shown in FIG. Although it has been changing, broken line B is the same as when a misfire occurs.
The NE pulse interval near ATDC 90 ° C A at the time of misfire becomes sharply longer than the NE pulse interval at the time of no misfire. The method of detecting the misfire state is not limited to this.
It may be determined that the average engine speed in the vicinity of ° C A is smaller than the immediately preceding average engine speed. Here, the average engine speed is calculated, for example, from the immediately preceding 180 ° C required time for each 45 ° C of NE pulse number CNIRQ = 1, 5, 9, 13 and is normally shown in FIG. However, when the engine misfires, it becomes as shown by the dotted line D. Therefore, under normal conditions, ATDC is near 90 ° C, that is, CNIRQ = 1.
Average engine speed NE13 at 3 is TDC or CNIRQ =
It is almost the same as the average engine speed NE5 in 5, but NE13 is significantly smaller than NE5 at the time of a misfire. Yotsutte
For example, it is possible to determine misfire because NE13 is lower than NE5 by a set value, for example, 50 rpm or more. Also, the injection amount Qsta 'at the final start is calculated with the NE pulse number CNIRQ = 9 because the spill angle (spill timing) that determines the injection amount is from the NE pulse number CNIRQ of 4 to 8 at the start. This is because the injection amount Qsta ′ at the final start can be calculated with the NE pulse number CNIRQ = 9, and the injection amount of the next cylinder can be set with a margin without interfering with the injection amount of the previous cylinder. . In addition, the command of the calculated injection amount at the time of starting can be issued at 30 to 60 ° C. after TDC immediately before the target cylinder. In the present embodiment, the misfire state is determined by determining that the NE pulse interval TNINT near ATDC 90 ° C. A is the NE pulse interval TN near TDC immediately before.
Although it was detected because it was 0.9 times or more of INTi, the method of detecting the misfire state is not limited to this, and for example, it can be determined as the misfire state when the set magnification is 0.80 to 1.00 or more. . Further, in the above embodiment, when the misfire state is detected, the starting injection amount of the next cylinder (after 720 ° C for a four cylinder engine) is reduced to 0.6 times the normal injection amount. The method of reducing the injection amount at startup is not limited to this,
For example, it can be set to a value 0.4 to 0.8 times the starting injection amount Qsta.

【The invention's effect】

As described above, according to the present invention, the fuel amount of the cylinder in which the misfire has occurred is reduced, so that the self-ignitability of the cylinder can be secured. Therefore, it has an excellent effect that the startability can be improved.

[Brief description of drawings]

FIG. 1 is a flow chart showing a gist of a method of controlling an injection amount of an electronically controlled diesel engine according to the present invention, and FIG. 2 shows an overall configuration of an embodiment of an electronically controlled diesel engine for an automobile to which the present invention is applied. FIG. 3 is a plan view showing the shape of the engine rotation (NE) pulser used in the above embodiment, and FIG. 4 is a view showing the structure of the electronic control unit. Block diagram shown, No. 5
Similarly, FIG. 6 is a flow chart showing an NE pulse input interrupt routine for determining the final starting injection amount, FIG. 6 is a diagram showing an example of the NE pulse in the above embodiment, and FIG. Similarly, FIG. 8 is a diagram showing an example of a method of calculating the hourly injection amount, and FIG. 8 is a diagram showing an example of a variation state of the engine speed at the time of starting depending on the presence or absence of misfire. 10 …… Diesel engine, 42 …… Injection pump, 42E …… Engine rotation (NE) pulser, 46 …… Engine rotation (NE) sensor, 50 …… Electromagnetic spill valve (SPV), 56 …… Electronic control unit (ECU) ), TNINT …… NE pulse interval, Qsta …… starting injection amount, Qsta i, Qsta (i + 1) …… cylinder start correction amount, Qsta ′ …… final starting injection amount, TNINTi …… TDC vicinity NE pulse interval .

Claims (3)

[Claims] 1. A method for controlling an injection amount of an electronically controlled diesel engine for instructing an injection amount at startup, which is determined by an engine temperature and an accelerator opening degree at the time of electronically controlling the injection amount according to an engine operating state. , The procedure to detect the starting state, and at the time of starting, detect the misfire state from the engine rotation state,
An electronically controlled diesel engine characterized by including a procedure for identifying a cylinder that has misfired, and a procedure for reducing the injection amount of the next misfiring cylinder from the injection amount at startup when a misfire condition is detected. Injection amount control method. 2. In the above misfire condition, the predetermined crank angle rotation required time near 90 ° C. A after top dead center is a predetermined magnification or more as compared with the predetermined crank angle rotation required time immediately before top dead center. The injection amount control method for an electronically controlled diesel engine according to claim 1, wherein the detection is performed. 3. The method according to claim 1, wherein the misfire state is detected because the average engine speed in the vicinity of 90 ° A after top dead center is smaller than the immediately preceding average engine speed. An injection amount control method for the electronically controlled diesel engine described.