JPH0351894B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel injection timing control device for controlling the fuel injection timing of a diesel engine in accordance with the ignition timing of fuel.

A configuration that detects the actual combustion timing of fuel in a cylinder of a diesel engine, and drives a fuel injection timing adjustment means to match the actual combustion timing with a target combustion timing calculated from signals from various operating state detectors. Conventionally, a fuel injection timing control means has been proposed in which the drive output of the fuel injection timing adjustment means is determined from the error between the target combustion timing and the actual combustion timing.

The present invention further improves this conventional device, improves control accuracy, and determines whether the ignition timing detector is malfunctioning or the fuel is cut off, and reliably prevents malfunctions when these ignition signals cannot be obtained. The object of the present invention is to provide a fuel injection timing control device that can perform the following steps.

FIG. 1 is an overall configuration diagram showing the configuration of an embodiment of the present invention and the flow of data within an electronic control unit.

The diesel engine 1 is supplied with fuel by injection from a fuel injection pump 2, and the fuel injection pump 2 is configured such that fuel injection is adjusted by an injection timing adjustment means 3. In the engine 1, the reference crank position, the actual timing of fuel ignition, the engine speed, and the accelerator position are detected by a reference position detector 4, an ignition timing detector 5, an accelerator position detector 6A, and a rotation speed detector 6D. .

The electronic control unit 10 calculates the target ignition timing θi from the rotational speed signal and the accelerator position signal, and calculates the basic duty ratio D _B from the target ignition timing θi and the rotational speed.
Calculate. Then, the actual ignition timing θ _R is calculated from the reference position signal from the reference position detector 4 and the ignition signal from the ignition timing detector 5, and an error calculation of θi−θ _R =Δθ is performed from the target ignition timing θi. Find Δθ.
An integral term ΔDi is determined from the error Δθ. Next, the output duty ratio D is calculated from the basic duty ratio D _B and the sum of the integral term ΔDi = ⁱ ΔDi, and a signal is output to the injection timing adjustment means 3 via the output means.

It also has a diagnosis function that determines whether the signal from the ignition timing detector 5 is being input normally. The output duty ratio D is calculated by setting the value to zero or the previous value. Then, this output duty ratio D is outputted through the output means to drive the injection timing adjustment means.

This specific configuration will be explained below with reference to the drawings. In FIG. 2, reference numeral 1 denotes a diesel engine, and fuel fed under pressure from a distribution fuel injection pump 2 is injected into each cylinder from a fuel injection nozzle 7. The fuel injection timing of the fuel injection pump 2 is adjusted by an injection timing adjustment means 3 called an electro-hydraulic timer.

The reference position detector 4 detects the reference crank position of the engine 1, and consists of a gear rotating in synchronization with the crankshaft of the engine 1 and an electromagnetic pickup facing the gear. This position detector 4 is also used to measure the engine speed.

The ignition timing detector 5 has a structure as shown in FIG. 4, for example. A rod-shaped body made of a light-transmitting material, for example, a heat-resistant glass rod 59 such as quartz glass, is set to penetrate the hollow part of a housing 58 made of a hollow cylindrical heat-resistant material. is adhesively fixed in the hollow part of the housing 58 using an appropriate adhesive 41. In this case, the heat-resistant glass rod 59 is set to protrude from the tip of the housing 58 by about 1 to 5 mm, and this protrusion functions as an ignition light detection section.

A light receiving element 61 such as a phototransistor for detecting ignition transmitted through the glass rod 59 is provided at the base end of the housing 58 and aligned in the axial direction of the glass rod 59. It is configured to detect ignition light and convert it into an electrical signal.

Figure 5 shows how the ignition timing detector is installed on a swirl chamber type diesel engine. 62 is a cylinder head, 63 is a piston, 64 is an exhaust valve, 65 is a swirl chamber, and 7 is a fuel injection nozzle. As shown in the figure, the ignition timing detector 5 passes through the cylinder head and is screwed onto the cylinder head 62. At this time, the ignition light detection section of the ignition timing detector 5 is preferably located at a position where the fuel spray injected from the fuel injection nozzle 7 hits and can wash away adhering soot and the like.

Further, the accelerator position detector 6A indirectly detects the actual fuel injection amount of the fuel injection pump 2, and a potentiometer or the like can be used.

The temperature detector 6B detects the engine fuel temperature (THF), and the battery detector 6C detects the battery voltage (+B). Further, the cooling water temperature detector 6E detects the cooling water temperature (THW) of the engine.

The electronic control unit 10 includes an A/D converter 11,
It consists of waveform type circuits 12 and 13, a microcomputer 14, and an output circuit 15. A microcomputer processes 8 or 12 bit data and has a CPU, memory, timer, etc.

Then, the electronic control unit 10 includes an output circuit 1
A pulse with a duty ratio appropriate from 5 is given to the hydraulic timer 3 to control the fuel injection timing.

The hydraulic timer 3 has a configuration as shown in FIG. 3, for example. In Fig. 3, the timer piston 30 is connected to a roller ring 32 by a pin 31, and when the timer piston 30 moves to the left in the figure, the roller ring 32 rotates in the clockwise rotation direction, and the fuel injection timing is advanced. It changes from side to side.

A vane type fuel pump 33 is rotated by a drive shaft (not shown) of the injection pump, and pumps fuel from the fuel tank to the pump internal pressure chamber 34 . The fuel in the pressure chamber 34 is injected into the engine and is guided to the timer piston high pressure chamber 35 through the throttle. Therefore, the position of the timer piston 30 is determined by the position where the pressure in the high pressure chamber 35 and the force of the return spring 36 in the low pressure chamber 38 are balanced, and therefore the position of the roller ring 32 is determined, and the injection timing is determined. 37
is a pressure regulating electromagnetic valve which controls the pressure in the high pressure chamber 35 by changing the opening/closing timing ratio in response to a drive signal from the electronic control unit 10, thereby determining the timer piston position, that is, the injection timing.

In the electronic control unit 10, the A/D converter 11 is of a type that outputs a digital signal according to an analog input voltage, and outputs a pulse signal whose width corresponds to the actual injection amount. It also converts the analog outputs of the cooling water temperature detector and accelerator detector into digital signals with an appropriate number of bits.

In the electronic control unit 10, the input circuit 12 also includes an ignition timing detector 5 as shown in FIG.
A voltage corresponding to the intensity of the input light is generated in the phototransistor 61, and this is sent to the amplifier circuit 54.
The waveform shaping circuit 55 converts the signal into a rectangular wave. Therefore, the output voltage generated at point B
Vc becomes as shown in Figure 8c.

An example of the input circuit 13 is shown in FIG. In FIG. 7, 41 is a gear that rotates in synchronization with the crankshaft of the reference position detector 4, and 42 is an electronic pick-up of the reference position detector 4. An AC signal as shown in FIG. 8a is output.

When this AC signal is input to the input circuit 13, it is waveform-shaped and has a period as shown in FIG. 8b.
A pulse signal Vb of T _N is output. The engine rotation speed can be calculated by inputting the detection signal of the reference position detector 4 to the microcomputer 14 through the input circuit 13 and counting the pulse interval T _N by the microcomputer 14. Further, the detection signal of the ignition timing detector 5 is input to the microcomputer 14 through the input circuit 12, and the difference T _T between the pulse and the detection signal of the reference position detector 4 is counted.
If the rotational speed is taken into account, the crank angle required from the reference crank position to the actual ignition of fuel, that is, the actual fuel ignition timing with respect to the reference crank position is determined.

FIGS. 9 to 14 are flowcharts showing the processing performed by the microcomputer, and the flow will be explained accordingly. Figure 9 is the main routine, Figure 10
1 to 14 show various interrupt routines.

In FIG. 9, step P1 is an initialization routine, which performs necessary initialization such as clearing the RAM, setting input/output ports, and setting initial values of each data when the power is turned on. In step P2, the reciprocal of the output pulse period T _N of the reference position detector 4 is taken and multiplied by a constant to obtain the rotational speed N _E . At this time, Figure 8b
An interrupt is generated at the rising edge of the output pulse of the reference position detector 4 shown in FIG. 10, and the pulse period T _N is set according to the reference position interrupt routine shown in FIG.
is found.

That is, in the reference position interrupt routine, the timer value ti at _the rising edge of the pulse shown in FIG _. Find (=ti−ti _-1 ).

Further, at the rising edge of the pulse signal from the ignition timing detector 5 shown in FIG. 8c, the actual ignition signal interrupt routine shown in FIG. 11 is activated. In this routine, the timer value tj at the rising edge of the pulse shown in FIG. 8c is read in step R15, ignition signal interrupt flags F1 and F2 are set to 1 in R16,
Next, in R17, the actual ignition timing T _T (=ti−tj) is determined from the reference position interrupt time ti, and the actual ignition timing interrupt routine is exited and the processing of the main routine is continued.
In this embodiment, the reference crank position signal is configured to generate one pulse per engine revolution, the ignition timing signal is detected from the first cylinder of the engine, and the control range of the ignition signal is set to BTDC (before top dead center) 5 °CA to ATDC
(After top dead center) 10°CA, the reference crank position signal is configured to be generated at BTDC10°CA. Therefore, as shown in FIGS. 8b and 8c, the actual ignition timing is calculated from the phase difference between the reference crank position signal and the ignition timing signal.

On the other hand, the ignition signal interrupt flags F1 and F2 at step R16 in FIG. 11 are provided to provide a diagnosis function and a fail-safe function, and are both set to 1 each time an ignition signal interrupts, as described above. . Further, the actual ignition timing T _T is calculated every time an ignition signal is generated.

Next, the ignition signal determination method will be explained with reference to FIG. In step R3, CN is a reference crank position signal, that is, a rotational speed signal interrupt counter, and as shown in FIG. 9, an ignition signal is inputted once every two pulses of the rotational speed signal are inputted. Therefore, if counter CN=2 is established, proceed to R4 and CN
=0. On the other hand, if CN≠2, proceed to R9 and add 1 to the counter CN. That is, it performs the calculation CN=CN+1 and exits from the interrupt routine. Next, in R5, determine whether the ignition signal interrupt flag F1=1,
If it is established, there is an ignition signal interrupt, and it is determined that the ignition signal is normal, the ignition signal interrupt flag F1 = 0 at R6, the error flag FER = 0 at R7,
At R8, the fuel cut flag FCUT is set to 0 and the routine exits from the reference position interrupt routine. On the other hand, when the ignition signal interrupt flag F1 = 0 in R5, there is no ignition signal interrupt even though the revolution pulse has been interrupted twice, so the injection amount Q is checked in the next R10. The set amount Q _S that indicates the injection amount Q,
For example, if it is larger than 10 mm ³ /st·cy ₁ , the engine is always ignited and burned, so it is assumed that the ignition sensor has failed and the error flag FER is set to 1 in the next R11, and the interrupt routine is exited. When Q<Q _S , it is determined that fuel is being cut during deceleration, etc., and the fuel cut flag FCUT is set to 1 in R12, and the interrupt routine is exited. The judgment flag F1 mentioned above,
F2, FCUT, FER and counter CN are steps
All are set to 0 in the initialization routine of P1.

Next, in FIG. 9, the accelerator position α is calculated in step P3. At this time, a program interrupt is made after the A/D conversion routine performed in the timer interrupt routine 1 shown in FIG. 12 is completed, and the accelerator position α is determined from the time difference Tα obtained in the program interrupt routine shown in FIG.
That is, in the timer interrupt routine 1 shown in FIG. 12, an interrupt is activated at regular intervals, and the value T _S of the timer at the time of activation is read in R20. A/D converter 11
starts A/D conversion at this point. A/ with R21
The end point of the output pulse of the D converter 11 is monitored, and when the A/D conversion is completed, the program jumps to the program interrupt routine shown in FIG. Then, the timer value T _E at the end of A/D conversion is
Read in R25 and subtract the time T _S from the time T _E to find the time difference Tα. This time difference Tα is a value indicating the output pulse width of the A/D converter 11, and has a value depending on the accelerator position.

Next, in step P4, the injection amount Q is calculated from the accelerator position α and the engine rotational speed _NE . Examples showing the relationship between the accelerator position α, the engine speed N _E and the injection amount Q are shown in FIGS. 15 and 16. 1st
Figure 5 shows what is called a maximum-minimum governor pattern, in which the injection amount increases in proportion to the accelerator position. Here, α ₁ represents the relationship between the engine rotation speed and the injection amount in the no-load idling operating state and α ₆ in the engine maximum load state. Further, between α ₁ and α ₆ , the injection amount increases successively to α ₂ , α ₃ , α ₄ , and α ₅ depending on the accelerator position. FIG. 16 shows what is called an all-speed cabana pattern, and as shown, the injection amount is determined from the accelerator position and the engine speed. Here, the injection amount can be determined using a map or a calculation formula.

In step P5, the signal from the engine coolant temperature detector 6E is input via the A/D converter 11 in the same manner as in step P3, and coolant temperature data THW is calculated.

In step P6, the basic ignition timing θ _B is calculated from the rotational speed N _E and the injection amount Q using a map or a calculation formula. Calculate the ignition timing θ _S at startup using a map or calculation formula using the cooling water temperature data THW to obtain the angle characteristics.
Find θi at the target ignition timing θi = MAX (θ _B , θ _S ).
FIG. 17 shows an example of the relationship between rotational speed, injection amount, and basic ignition timing, and FIG. 18 shows an example of the relationship between cooling water temperature and ignition timing at startup.

In step P7, the rotational speed N _E and the target ignition timing θi
From this, calculate the basic duty ratio (basic drive output) D _B using a map or calculation formula. FIG. 19 shows an example of the relationship among the rotation speed, target ignition timing, and basic duty ratio.

In step P8, the signals of the battery voltage detector 6C and fuel temperature detector 6B are inputted via the A/D converter 11 in the same manner as in step P3, and the battery voltage data +B and fuel temperature data are respectively input.
Calculate THF. In P9, the corrected duty ratio Db is calculated using +B and THF. This is solenoid valve 3
Since the response of 7 changes depending on the battery voltage, this is corrected by changing the duty ratio. Also, since the viscosity of the fluid (fuel) changes depending on the fuel temperature, this is also corrected by changing the duty ratio. Therefore, the correction amount is calculated in P9.

Next, in P10, the difference Δθi=θij−θij ₋₁ between the previous target ignition timing θij ₋₁ and the current target ignition timing θij is calculated, and the expected correction amount Dd is calculated according to the magnitude of Δθi. This P10 is a process for improving the responsiveness of the timer piston 30, and has the effect of quickly converging to the target ignition timing when the amount of change Δθi of the target ignition timing per unit time is large.

In step P11, it is determined whether the error flag FER=1 or not, and if the ignition sensor system has failed and the ignition signal is not being input, step P12 is executed.
Proceed to failsafe processing. That is, in P12, the output duty ratio D is calculated using the formula D=D _B +Db+Dd, and the process proceeds to step 2, where the above-described processes are sequentially repeated. In P11, when FER=0, that is, the ignition sensor system is normal, the process proceeds to P13, where it is determined whether the fuel cut flag FCUT=1. When not in the fuel cut state, FCUT=0, and proceed to P14.

At P14, look at the ignition signal interrupt flag F2,
If there is an ignition signal interrupt, F2=1 and the process proceeds to P15. In P15, F2 is set to 0 and the following error calculation is stopped until the next ignition signal interrupt occurs.

In P16, the actual ignition timing θ _R is determined from T _T obtained in R17 _.
Calculated using the formula = (T _T /T _N ) x 360 (°CA). In P17, θ _R obtained in P16 is averaged.
For example, there is an averaging method in which the previous value θ _R i _-1 and the current value θ _R I are stored and θ _R =(θ _R i +θ _R i _-1 )/2.

In P18, the error Δθ is calculated from the target ignition timing θ _i and the actual ignition timing _R from Δθ=θi−θ _R , and the integral amount ΔDi is calculated according to the value of this Δθ. In P19, the integral amount ΔDi
Find the sum Di from Di= 〓 ⁱ ΔDi. Therefore, Di is updated every time the ignition signal interrupts, and variations in the engine, injection system, etc., changes over time, etc. are calculated as the offset amount Di, and the target ignition timing always matches the actual ignition timing, that is, θi - θ _R = 0. In the next step P20, the output duty ratio D is calculated in order to be controlled so that the output duty ratio D is controlled as follows. That is, D=D _B +Db+Dd+Di
The output duty ratio D is calculated using the following calculation formula, and the process returns to step P2. FIG. 20 shows an example of the relationship between Δθi and the expected correction amount Dd, and FIG. 21 shows an example of the relationship between Δθ and the integral amount ΔDi.

If FCUT=1 at step P13, that is, the fuel is cut off during deceleration, etc., the process jumps to P20. Similarly, when F2=0 in step P14, that is, when there is no ignition signal interrupt, the process also jumps to P20. At this time, since error calculation etc. are being performed, the sum of the integral terms is
For Di, the value when the previous ignition signal interrupt occurred is used. For example, if the engine is running at 600 rpm, the ignition signal interruption is 200 m.
It occurs once every sec, but the main routine goes through one cycle every few msec, so the value of Di is no longer determined due to errors, and as the rotation speed increases, the ignition signal interrupt interval becomes shorter and cannot be uniquely defined. This is a process to eliminate it.

After proceeding to step P12 or P20, the program returns to P2 and output duty ratio D
Repeat the same process to calculate . In this way, while the program is drawing a loop and proceeding with calculations, the timer interrupt routine 2 shown in Figure 14 occurs at certain fixed time intervals, R30 processes the fixed time interrupt, and R31 sends the calculation to the output circuit 15. Outputs a pulse with the specified duty ratio. Timer interrupt routine 2 occurs in synchronization with the drive output cycle.

In this embodiment, the corrected duty ratio Db was obtained using the battery voltage + _B and the fuel temperature THF to obtain the output duty ratio D. It can also be controlled by calculating it as In addition, the expected term Dd was calculated from the change in the target ignition timing, but the basic duty ratio
It is also possible to obtain it from the change in D _B.

Next, a second embodiment will be explained with reference to FIG. 22. However, only processing routines that are different from the first embodiment described above will be explained. The process is executed up to step P11, and if FCUT=1 in step P13, that is, the fuel is cut off, the process jumps to P12, where the output duty ratio is calculated using the formula D=D _B +Db+Dd, and the integral term is calculated in P21. Return to P2 with the sum Di=O. Further, since the processing after P14 is the same as that in the first embodiment, the explanation here will be omitted.

Next, a third embodiment will be explained with reference to FIG. 23. In the reference calculation position interrupt routine, that is, the rotation speed signal interrupt routine, the first
Execute the process described in the example, and when F1≠1 in R5,
In other words, when there is no ignition signal interruption, it jumps to R13. In R13, when the accelerator position α is greater than or equal to a certain set value αS, that is, when the injection amount pattern is a maximum-minimum governor pattern as shown in FIG. correspondingly, for example αs
= 5%, a relationship such that Q is 10 mm ³ /st·cy1 is established, so if there is no ignition signal at that time, it is assumed that the ignition signal system is malfunctioning, and the process proceeds to R11 and returns with an error flag FER=1. Also α
When <αs, the fuel cut state is determined and the fuel cut flag FCUT=1 is returned. Therefore, if the engine has the injection amount pattern shown in FIG. 15, it is possible to accurately determine at the accelerator position whether there is a failure in the ignition sensor system or a fuel cut state.

As described above, according to the present invention, even when it is impossible to detect the ignition timing, such as in the case of a failure or fuel cut, the basic ignition timing is calculated based on the target ignition timing calculated according to the engine speed and the accelerator opening. Since the injection timing adjustment means can be controlled according to the control amount, sudden changes in the injection timing can be prevented and injection timing control that is always appropriate to the operating conditions can be continued, which is excellent for purifying engine exhaust gas and improving fuel efficiency. It has a positive effect.

[Brief explanation of drawings]

FIG. 1 is an overall configuration diagram for clearly showing the configuration of the present invention, FIG. 2 is an overall configuration diagram showing a first embodiment of the invention, and FIG. 3 is a diagram showing the injection timing adjustment means shown in FIG. 2. 4 is a partial sectional view showing the ignition timing detector shown in FIG. 2; FIG. 5 is a sectional view showing how the ignition timing detector is mounted on the engine; FIG.
7 is an electric circuit diagram showing each of the input circuits shown in FIG. 2, FIG. 8 is a signal waveform diagram at each part of the input circuit shown in FIGS. 6 and 7, and FIGS. A flowchart for explaining the operation of the embodiment,
FIG. 15 is a diagram showing a maximum-minimum injection amount pattern, FIG. 16 is a diagram showing an all-speed injection amount pattern, and FIG. 17 is a characteristic diagram showing an example of basic ignition timing determined by engine speed and injection amount.
Fig. 18 is a characteristic diagram showing an example of the ignition timing at startup determined by the engine cooling water temperature, Fig. 19 is a characteristic diagram showing an example of the basic duty ratio determined by the engine speed and target ignition timing, and Fig. 20 is a characteristic diagram showing the target ignition timing. FIG. 21 is a characteristic diagram showing an example of the relationship between the expected term Dd and the rate of change in ignition timing Δθi. FIG. 21 is a characteristic diagram showing an example of the relationship between the integral term ΔDi and the error Δθ. FIG. 22 is a characteristic diagram showing an example of the relationship between the integral term ΔDi and the error Δθ. FIG. 23 is a flowchart for explaining the operation of the third embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Diesel engine, 2... Fuel injection pump, 3... Injection timing adjustment means, 4... Reference position detector, 5... Ignition timing detector, 6A... Accelerator position detector, 10... Electronic control Unit, 30...
...Timer piston, 37...Solenoid valve.

Claims (1)

[Scope of Claims] 1. A fuel injection timing control device that has an injection timing adjustment means for electrically calculating a control amount, and controls the injection timing by displacing the injection timing adjustment means, comprising: an ignition timing detector for detecting the actual ignition timing θ _R of fuel injected into the cylinder of the engine via the injection timing adjusting means; and the operating condition detector. a target ignition timing calculation means for calculating a target ignition timing θi according to the engine rotational speed and the accelerator opening degree detected by the ignition timing detector; determination means for determining the basic control amount D _B of the injection timing adjustment means according to the target ignition timing θi, regardless of whether the condition is satisfied;
basic control amount calculation means for calculating the error Δθ between the actual ignition timing θ _R and the target ignition timing θi;
Accordingly, a correction value calculating means for calculating a correction value Di of the basic control amount D _R ; and a final control amount D of the injection timing adjusting means by correcting the basic control amount D _B with the correction value Di. and final control amount calculation means for calculating and driving the injection timing adjustment means according to the final control amount D, and the final control amount calculation means is configured to control at least the target ignition timing when the condition is not satisfied. A fuel injection timing control device characterized in that a final control amount D is calculated in accordance with the basic control amount D _B corresponding to the basic control amount D B.