JPH063165B2 - Injection timing control method for electronically controlled diesel engine - Google Patents

Description

Detailed Description of the Invention [Industrial applications]

The present invention relates to an injection timing control method for an electronically controlled diesel engine, and in particular, an ignition signal obtained by detecting ignition in a combustion chamber, which is suitable for use in an electronically controlled diesel engine for an automobile equipped with an ignition timing sensor. And an improvement of an injection timing control method for an electronically controlled diesel engine in which the ignition timing is obtained from a crank angle signal as a reference position signal of the ignition timing and the injection timing is electronically feedback-controlled.

[Prior art]

In controlling the injection timing for optimizing the exhaust gas purification performance of a diesel engine, especially a diesel engine for automobiles, JP-A-57-28842 and JP-A-58-25 are known.
582, JP-A-58-192935, and JP-A-59-15.
3942 etc., an ignition timing sensor such as a fire sensor is installed in the combustion chamber, and the ignition timing in the combustion chamber by the ignition timing sensor (the timing when combustion light rises due to ignition or the pressure in the cylinder rises rapidly due to combustion). It is proposed that the injection timing be feedback-controlled so that the actual ignition timing becomes the target ignition timing determined by the engine load, the engine speed, etc. by feeding back the detection result of (the rising timing). In feedback control of the injection timing based on the output signal of the ignition timing sensor, as shown in FIG.
At the same time as the ignition signal (Fig. 8 (D)) obtained by detecting the ignition in the combustion chamber by the ignition timing sensor, it is generated at a predetermined position in synchronization with the rotation of the engine or the injection pump as a reference position signal of the ignition timing. A crank angle signal (Fig. 8 (B)) is required. Generally, only one cylinder is required as the ignition timing sensor, so a four-cylinder engine will obtain an ignition signal once at 720 ° CA. Therefore, in this case, the crank angle signal is preferably pump rotation synchronization (1 time / 720 ° CA) rather than engine rotation synchronization (1 time / 360 ° CA). Further, the conventional ignition timing feedback control according to the crank angle signal and the ignition signal is performed according to the procedure shown in FIGS. 9 and 10. That is, first, when the crank angle signal is input, the crank angle signal input interrupt routine shown in FIG. 9 is started, and the crank angle signal input time Tca is stored in step 110. Next, when the ignition signal is input, the ignition signal input interrupt routine shown in FIG. 10 is started, the ignition signal input time Tig is stored in step 210, and the difference between Tca and Tig and the average engine at that time are calculated in step 212. From the rotational speed NE, using the following equation, Tca
An angle (detection ignition timing) ACTig between −Tig is calculated. ACTig ← (Tig−Tca) / (60 × 10 ⁶ / NE × 3
60) (1) Then, the average engine speed NE and the injection amount command value Qfin
Using the target ignition timing TRGig calculated in advance, in steps 214 and 216, the magnitude relationship between the detected ignition timing ACTig and the target ignition timing TRGig is compared. When the detected ignition timing ACTig is larger than the target ignition timing TRGig, in step 218, the timer control valve that controls the injection timing by controlling the position of the timer piston for changing the rotational position of the roller ring. (Hereinafter TCV
The control duty ratio FTduty (referred to as)) is reduced to slightly advance. On the contrary, when the detected ignition timing ACTig is smaller than the target ignition timing TRGig, step 22
At 0, the control duty ratio FTduty is increased to make it slightly retarded. When the detected ignition timing ACTig matches the target ignition timing TRGig, the control duty ratio FTduty
Is left as is. In this way, the injection timing is feedback-controlled so that the detected ignition timing ACTig and the target ignition timing TRGig match. On the other hand, here, the crank angle signal is as shown in FIG.
Normally, an output waveform obtained electromagnetically by the relative movement of the pulsar 42P, which is a protrusion provided at a predetermined position on the pump drive pulley 42D, and the crank angle sensor 44, which is a magnet pickup in the vicinity of the pulsar 42P (Fig. 8 (A )) Is used after being corrugated (FIG. 8 (B)). At this time, in order to eliminate the influence of machining accuracy and position variation of the pulsar 42P and other tolerances of each part, the engine is set in an idle state before shipment, and the position where the crank angle signal is generated is the top dead center (hereinafter referred to as TDC) of the engine. )
On the other hand, the position of the crank angle sensor 44 is dynamically adjusted using a timing light or the like so as to be a predetermined position.

[Problems to be Solved by the Invention]

However, the output waveform (FIG. 8 (A)) shows that the gap G between the crank angle sensor 44 and the pulsar 42P (11th
(See FIG. 12 and FIG. 12), the zero cross point (FIG. 8 (A)) of the output waveform shifts due to changes in the time constant and magnetic flux density on the circuit. 13 to 15 show examples of changes in the phase delay depending on the average engine speed NE and the size of the gap G. As is clear from FIG. 13 and FIG. 14, even if the gap G is wide, there is not much difference in idle speed from when the gap G is narrow. However, even if the idling adjustment is set to a predetermined value, a wide gap G causes a large delay at high revolutions in which the output is delayed, as shown in FIGS. 13 and 15. If ignition feedback is performed in this state, the reference position is delayed, so the detected ignition timing ACTig and the target ignition timing T
When RGig is matched, the ignition timing is retarded by the phase delay, as shown in FIG. 16, as compared with the case where the gap G is normal, and the injection timing is substantially delayed, and the exhaust temperature rises. There is a possibility of causing serious problems such as a decrease in output. On the contrary, if the gap G is too narrow, the injection timing advances, leading to a rise in the temperature of the combustion chamber, an increase in exhaust black smoke, deterioration of the emission, and the like.

[Object of the Invention]

Since the present invention has been made to solve the above-mentioned conventional problems, the injection timing can be accurately controlled regardless of the difference in the output waveform of the crank angle signal due to the variation in the gap between the crank angle sensor and the pulser. An object of the present invention is to provide an injection timing control method for an electronically controlled diesel engine.

[Means for solving problems]

According to the present invention, the input timing Tig of the ignition signal obtained by detecting the ignition in the combustion chamber and the signal obtained by detecting the passage of the pulser rotating according to the crank rotation by the crank angle sensor are waveform-shaped by the waveform shaping circuit. Based on the input timing Tca of the formed crank angle signal, the actual ignition timing AC
In an injection timing control method for an electronically controlled diesel engine in which the injection timing is electronically feedback-controlled so as to obtain Tig and match with the target ignition timing TRGig, as shown in the outline of FIG. A means for detecting the peak level Vpp of the signal before waveform shaping, and a reference of the peak level Vpp according to the deviation from the reference value of the gap between the pulsar and the crank angle sensor 44 when passing through the pulsar. A step of detecting a deviation from the value, and by using the detected deviation of the peak level, it is possible to reduce the timing deviation of the ignition timing due to the deviation from the reference value of the gap during the feedback control. Thus, the above-mentioned object is achieved. Further, in the embodiment of the present invention, the deviation of the peak level Vpp from the reference value is detected when the engine speed is within the set range. Further, in the embodiment of the present invention, the injection timing is relatively advanced as the peak level Vpp is smaller than the reference value. Also, in the embodiment of the present invention, the injection timing is corrected by shifting the reference position detected by the crank angle signal.

[Action]

The present invention has found that the phase difference between the signals output by the crank angle sensor changes according to the gap between the crank angle sensor and the pulser, which reduces the accuracy of feedback control of the injection timing. It is a thing. Also, the peak level V of the crank angle sensor
pp focuses on that it changes according to the gap between the crank angle sensor and the pulser. Therefore, in the present invention, the phase difference due to the gap shift is corrected by the peak level Vpp of the signal output from the crank angle sensor before waveform shaping, and the accuracy of feedback control of the injection timing is improved. . by this,
Even if the output waveform of the crank angle signal changes due to variations in the gap between the crank angle sensor and the pulser, optimal injection timing control can be performed. Further, when the deviation of the peak level Vpp from the reference value is detected when the engine speed is within the set range, the deviation can be easily and accurately detected. Also, the smaller the peak level Vpp is compared with the reference value,
When the injection timing is relatively advanced, the injection timing can be accurately corrected. Further, when the correction of the injection timing is performed by shifting the reference position detected by the crank angle signal, the injection timing can be easily corrected.

【Example】

An embodiment of an electronically controlled diesel engine for an automobile, in which an injection timing control method according to the present invention is adopted, will be described in detail below with reference to the drawings. As shown in FIG. 2, the embodiment of the present invention is provided with an intake air temperature sensor 12 arranged 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 turbocharger 1
The upstream side of the turbine 14A and the downstream side of the compressor 14B of No. 4 are connected 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 position of the accelerator pedal 17 (hereinafter referred to as an accelerator opening amount) Accp 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 association with rotation of the crankshaft of the diesel engine 10.
A feed pump 42B for pressurizing the fuel, which is fixed to the pump drive shaft 42A (FIG. 2 shows a state in which it is expanded by 90 °), and a fuel pressure adjusting valve 42C for adjusting the fuel supply pressure, A crank angle sensor 44 similar to the conventional one for detecting a crank angle reference position, for example, top dead center (TDC) from the rotational displacement of the pump drive shaft pulley 42D fixed to the pump drive shaft 42A, and the same pump drive shaft. An engine speed sensor 46, which is, for example, an electromagnetic pickup, for detecting the engine speed from the rotational displacement of a gear 42E fixed to 42A, and a face cam 42F.
And a roller ring 42H for reciprocating the plunger 42G and changing its timing, and a timer piston 42J for changing the rotational position of the roller ring 42H (FIG. 2 shows a 90 ° unfolded state). And a TCV 48 for controlling the injection timing by controlling the position of the timer piston 42J, and a spill port 42
The electromagnetic spill valve 50 for controlling the fuel injection amount by changing the fuel escape timing from the plunger 42G via K, the fuel cut valve 52 for cutting the fuel, the backflow of fuel and the backward droop. And a delivery valve 42L for prevention. 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,
A crank angle sensor 44, an engine speed 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,
Neutral safety switch output, vehicle speed signal, etc.
It is input to an electronic control unit (hereinafter referred to as ECU) 56 for processing, and the output of the ECU 56 causes the V
The SVs 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 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, referred to as ROM), a random access memory (hereinafter referred to as RAM) 56C for temporarily storing operation data 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.
A multiplexer (hereinafter referred to as MPX) 56K for sequentially taking in an output, the output of the crank angle sensor 44 before waveform shaping, and an analog-digital converter for converting an analog signal of the MPX 56K output into a digital signal. 56L (hereinafter referred to as A / D converter) and the A / D converter
An input / output port 56M for taking in the output of the converter 56L to the CPU 56A, a starter signal input via the buffer 56N, an air conditioner signal input via the buffer 56P, and a torque converter signal input via the buffer 56Q, An input / output port 56S for taking in the output of the ignition timing sensor 38 or the like input through the waveform shaping circuit 56R to the CPU 56A, and waveform shaping of the output of the ignition timing sensor 38 to input interrupt terminal ICAP2 of the CPU 56A.
Waveform shaping circuit 56R for directly capturing into the CPU, and waveform shaping of the output of the crank angle sensor 44 into the CPU 56.
A waveform shaping circuit 56T for directly taking in the same input interrupt terminal ICAP2 of A, and the engine speed sensor 46
A waveform shaping circuit 56U for waveform shaping the output and directly fetching it into the CPU 56A, a drive circuit 56V for driving the electromagnetic spill valve 50 according to the calculation result of the CPU 56A, and a calculation result of the CPU 56A. Drive circuit 56W for driving the TCV 48 and the C
A drive circuit 56X for driving the fuel cut valve 52 according to the calculation result of the PU 56A, and a common bus 5 for connecting between the respective constituent devices and transferring data and commands.
6Y. Here, the ignition signal output from the waveform shaping circuit 56R is
Not only the input interrupt terminal ICAP2 of the PU 56A but also the input / output port 56S is input in order to distinguish it 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 crank angle signal input interrupt routine in this embodiment is as shown in FIG. 4, and after step 110 similar to the conventional example shown in FIG.
The engine speed NE is within a set range, for example, 2950-30
Determine if it is within 50 rpm. When the determination result is positive and it is determined that the deviation of the peak level of the crank angle signal before waveform shaping from the reference value needs to be detected, the routine proceeds to step 122, where the crank angle signal peak level Vpp ( According to FIG. 8 (A)), RO
Pre-stored in M56B. As shown in FIG.
Using the relationship between the peak level Vpp and the correction time ΔTca,
The correction time ΔTca is calculated and stored in memory. Next, the routine proceeds to step 124, where the corrected crank angle signal input time Tca ′ (μsec) is calculated by adding the correction time ΔTca to the crank angle signal input time Tca obtained at step 110, as shown in the following equation: To memory. Tca ′ ← Tca + ΔTca (2) Therefore, for example, when the peak level Vpp is smaller than 1.7 V when the gap G is normal, the correction time ΔTca <0.
And Tca ′ <Tca. Next, in the ignition signal input interrupt routine shown in FIG.
After completion of step 210 similar to the conventional example shown in FIG. 10, the detected ignition timing ACTig is calculated by the following equation (3) at the end of equation (1) at step 230. ACTig ← (Tig−Tca ′) / (60 × 10 ⁶ / NE × 360) (3) After step 230, the same step 214 as the conventional example
Then, the procedure similar to the conventional example is performed thereafter. Therefore, as shown in FIG. 7, when the peak level Vpp is smaller than the reference value 1.7V, the detected ignition timing ACTig becomes a larger value than when it is the reference value. And the injection timing is advanced to the same injection timing as when the reference value is 1.7V. On the contrary, when the peak level Vpp is larger than the reference value 1.7V, the detected ignition timing ACTig is calculated to be a smaller value than when the peak value Vpp is the reference value, so that the injection timing is delayed as compared with the conventional case, and , Reference value 1.
The injection timing is the same as when it is 7V. In addition, step 12 of the crank angle signal input interrupt routine shown in FIG.
Even outside the determination rotation range of 0, the correction time ΔTca is stored in the memory, so the correction is performed in the entire area. In this embodiment, the deviation of the peak level Vpp before waveform shaping of the crank angle signal from the reference value (1.7 V in the embodiment) is set in the setting range of the engine speed NE (29 in the embodiment).
Since it is detected when the speed is 50 to 3050 rpm), the deviation of the peak level Vpp from the reference value can be detected easily and accurately. The method of detecting the deviation of the peak level Vpp from the reference value is not limited to this. For example, the deviation may be detected when the engine speed NE is in another setting range, or the deviation may be made to correspond to the engine speed. It is also possible to detect the deviation of the peak level Vpp from the reference value in all engine speed regions by providing a map of the reference value. Further, in this embodiment, as shown in FIG. 5 described above, the injection timing is relatively advanced as the peak level Vpp of the crank angle signal is smaller than the reference value. The time can be corrected accurately. In addition,
The method of correcting the injection timing according to the deviation of the peak level Vpp from the reference value is not limited to this, and it is also possible to make a stepwise correction, for example. Further, in the present embodiment, the injection timing is corrected by correcting the reference position detected by the crank angle signal by a correction time ΔT.
Since it is performed by shifting by ca, the injection timing can be easily corrected. The method of correcting the injection timing is not limited to this, and it is also possible to correct the detected ignition timing ACTig calculated by the formula (1) of the conventional example or to correct the target ignition timing TRGig. It is possible. In the above-described embodiment, the present invention is applied to the automobile diesel engine with the turbocharger in which the fuel injection amount is controlled by the electromagnetic spill valve 50, but the application range of the present invention is not limited to this. However, it is obvious that the same can be applied to a general electronically controlled diesel engine equipped with a fuel injection amount control actuator other than the electromagnetic spill valve.

【The invention's effect】

As described above, according to the present invention, optimum injection timing control is performed according to the operating conditions of the engine, regardless of changes in the output waveform of the crank angle signal due to variations in the gap between the crank angle sensor and the pulser. It has an excellent effect that

[Brief description of drawings]

FIG. 1 is a flow chart showing the outline of the injection timing 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 a configuration of an electronic control unit used in the above-described embodiment, and FIG.
Flow chart showing a crank angle signal input interrupt routine, fifth
FIG. 6 is a diagram showing an example of the relationship between the peak level of the crank angle signal and the correction time, which is used in the routine, and FIG.
FIG. 7 is a flow chart showing an ignition signal input interrupt routine used in the above embodiment, and FIG. 7 is a crank angle signal when the gap between the crank angle sensor and the pulser in the embodiment is normal and wide. FIG. 8 is a diagram showing an example of a relationship between a crank angle sensor output waveform, a crank angle signal, an ignition timing sensor output waveform, and an ignition signal. FIG. 10 is a flowchart showing an example of a conventional crank angle signal input interrupt routine, FIG. 10 is a flowchart showing an example of a conventional ignition signal input interrupt routine, and FIG. 11 shows a mounting state of a pulsar and a crank angle sensor. , A cross-sectional view of a pump drive pulley, twelfth
FIG. 13 is a transverse sectional view taken along line XII-XII in FIG.
FIG. 14 is a diagram showing an example of the relationship between the average engine speed and the phase delay when the gap between the crank angle sensor and the pulsar changes, and FIG. 14 shows the crank angle sensor when the gap changes at idle speed. FIG. 15 is a diagram showing a comparison of output waveforms, and FIG. 15 is a diagram showing a comparison of output waveforms of a crank angle sensor when a gap is changed at high speed rotation.
FIG. 6 is a diagram showing a comparative example of the relationship between the crank angle signal and the ignition signal when the gap between the crank angle sensor and the pulser is normal and when the gap is wide in the conventional example. 10 ... Diesel engine, 38 ... Ignition timing sensor, 42 ... Fuel injection pump, 42P ... Pulsar, 44 ... Crank angle sensor, 48 ... Timer control valve (TCV), Tca ... Crank angle signal input time, ACTig ... Detected ignition timing, TRGig ... Target ignition timing, FTduty ... Control duty ratio, Vpp ... Peak level of crank angle signal, ΔTca ... Correction time, Tca '... Crank angle signal input time after correction.

Claims (4)

[Claims] 1. An input timing Tig of an ignition signal obtained by detecting ignition in a combustion chamber, and a signal obtained by detecting passage of a pulser rotating according to crank rotation by a crank angle sensor by a waveform shaping circuit. Based on the input timing Tca of the waveform-shaped crank angle signal, the actual ignition timing A
In the injection timing control method of the electronically controlled diesel engine, in which CTig is obtained and the injection timing is electronically feedback-controlled so as to match the target ignition timing TRGig, the peak level Vpp of the crank angle signal before waveform shaping is calculated. And a procedure for detecting a deviation of the peak level Vpp from a reference value according to a deviation of a gap between the pulsar and the crank angle sensor from a reference value when the pulsar passes through. The use of the detected deviation of the peak level reduces the timing deviation of the ignition timing due to the deviation of the gap during the feedback control from the reference value. Timing control method. 2. The injection timing control method for an electronically controlled diesel engine according to claim 1, wherein the deviation of the peak level Vpp from the reference value is detected when the engine speed is within a set range. 3. The injection timing control method for an electronically controlled diesel engine according to claim 1, wherein the injection timing is relatively advanced as the peak level Vpp is smaller than a reference value. 4. The injection timing control method for an electronically controlled diesel engine according to claim 1, wherein the correction of the injection timing is performed by shifting a reference position detected by a crank angle signal.