JPS5870029A - Apparatus for controlling timing for jetting fuel - Google Patents

Abstract

PURPOSE:To eliminate the influences such as the scatter of compression ratio of an engine, by detecting the combustion timing of an internal combustion engine by a photodetector, and controlling jetting timing adjusting means such that the measured value of the timing of combustion coincides with an aimed value. CONSTITUTION:An electrical control means 4 uses a crank shaft positional signal as the reference to determine the jetting timing aimed value from a detected signal from a running state detector 1. According to the difference between it and the actual combustion timing from the photodetector 3, the fuel jetting timing of the jet pump 6 is adjusted. Thus since the predetermined jetting timing can be effected very precisely, both purification of exhaust gas and lowering of the cost of fuel become possible.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel injection timing control device for a diesel engine.

In recent years, social demands for purifying exhaust gas and improving fuel efficiency have been increasing for diesel engines as well, and one effective way to achieve this is to finely and precisely control fuel injection timing according to engine operating conditions. There is a need for a fuel injection timing control device that achieves this goal.

Therefore, an injection timing control device has been proposed that detects operating conditions such as engine speed and injection amount using an electrical operating condition detector, and electrically controls the injection timing adjustment mechanism of the injection pump according to the operating condition. However, this type of device returns control results by detecting the operating amount of the operating member of the injection timing adjustment mechanism or the valve lift of the injection nozzle of the fuel injection system, and calculates the calculated target value. It is configured to compare and correct errors in injection timing, and has the ability to adapt to injection system buffiness and changes over time. The problem was that they did not have the ability to adapt to changes in time.

Therefore, in the present invention, the timing when the fuel injected into the cylinders of the engine actually starts to burn is detected as an electrical signal by a photodetector from light generated during combustion, and detection signals from various operating state detectors are also detected. This invention proposes an injection timing control device that detects an error in the actual combustion timing with respect to the target combustion timing calculated according to the engine The purpose of the present invention is to achieve a set combustion timing, that is, an injection timing t-, without being affected by variations in the injection system, changes over time in the injection system, variations in the compression ratio, or differences in fuel properties.

Hereinafter, one embodiment of the present invention shown in the t-diagram will be described.

Fig. 1 is an overall configuration diagram, and l is an operating state detector, which detects the engine speed, the amount of fuel injected into the engine, the intake pressure and intake air temperature for determining the intake air density, and the engine cooling water. It detects temperature, etc. and generates an electrical signal. 2 is a detector that detects the engine crankshaft position;
A reference position signal, that is, a reference combustion timing signal is generated at a constant rotation angle of the crankshaft. Reference numeral 8 denotes a photodetector, which detects when the fuel injected into the cylinders of the engine actually starts to burn, using the light generated during combustion. Configure. Reference numeral 4 denotes an electrical control means, which uses the crankshaft position signal as the reference combustion timing signal as a reference and uses the detection signal from the operating state detector 1 as a control buff meter to determine the optimal injection timing target value, that is, the combustion timing target value for the engine. At the same time, it compares it with the detection signal from the photodetector 8, and generates an electrical output to correct the error in accordance with the error in the actual combustion timing with respect to the target combustion timing. Reference numeral 6 denotes an injection timing adjusting means, which is driven by an electrical output from the electric control means and adjusts the fuel injection timing of the injection pump with respect to the reference combustion timing signal. 6 is a fuel injection cylinder, and 7 is a diesel engine.

In the operating state detector l, the engine rotation speed can be detected by placing an electromagnetic pickup facing a gear-shaped inductor engaged with the engine crankshaft and using a pulse number proportional to the rotation speed≠. In the embodiment, it is calculated from the cycle of the reference combustion timing signal. The amount of fuel injected into the engine, that is, the injection amount, is detected by an injection amount sensor 16, and specifically, it is determined and detected as an electrical signal by a position tube position detector of a fuel joint member of a fuel injection pump. As the position detector, a 3-meter meter or a differential transformer can be used, and a signal proportional to the amount of paper injection can be obtained. A semiconductor pressure sensor can be used as the rounded intake pressure sensor 18 for determining the amount of intake air, and a thermistor or the like can be used as the intake air temperature sensor 17.
Furthermore, a thermistor can be used as the engine cooling water temperature sensor 16.

The engine crankshaft position detector 2 is provided with an inductor that engages with the crankshaft, detects a reference position using an electromagnetic pickup, and obtains a reference combustion timing signal. An embodiment of the reference combustion timing signal is shown in FIG. 2 as a photodetector 8 which also serves as a rotational speed signal.

In this embodiment, a transistor is used as the photodetecting element. 1O is an engine glue cylinder head, and is provided with a screw hole to which a photodetector 3 can be attached. If is a housing, and 12 is a sapphire material through which combustion light can pass, and is fixed to the housing 11 because it can withstand vibration and heat sufficiently.

18 is an electrically insulating plate on which a phototransistor 14 as a photodetecting element is attached; 14&;

14b is its electrode.

When fuel is injected into the combustion chamber and combustion begins, the combustion light passes through the sapphire 12 and the phototransistor 14.
The electric signal of combustion is obtained between the electrodes 14a and 14b. This combustion signal is the intertwist firing timing signal.

Next, an example of the brick configuration of the electrical control means 4 is shown in FIG. 3. The electrical control means 4 includes a central processing unit (CPU) 41. A waveform shaping circuit 42 has a built-in microphone computer whose main elements are a memory (ROM) 44 and a memory (RAM) 45, and shapes the output signal of the crankshaft position sensor 3 and the output signal of the photodetector 8.
, various analog input signals from the operating status detector l
Mu/D converter 48 for D conversion. and a drive circuit 46 for amplifying the pulse output signal from the 0PU 41 and obtaining an electric signal that enables the injection timing adjustment means 6 to be driven.

Next, regarding the injection timing articulating means 5, a case will be described in which the present invention is applied to a fuel injection pump with a distribution source.

FIG. 4 is a sectional view of the main parts of the Bosch distribution type fuel injection pump. The timer piston 51 is connected to the p-touring Ss by a lever 54, and when the timer piston 51 moves to the left in the figure, the lobe ring 53 rotates to the right, and the fuel injection timing changes to the advance side. It is. 56
is a vane type fuel pump, which is rotated by a drive shirt (not shown) of the injection pump, and pumps fuel from the fuel tank to the pressure chamber inside the pump. 66 is an overflow check pulp, which prevents an excessive rise in pressure in the pump internal pressure chamber. The fuel in the pump internal pressure chamber B is injected into the engine and is guided to the timer piston high pressure chamber B through the throttle.

Therefore, the position of the timer piston 51 is determined by the balance between the pressure in the timer piston high pressure chamber B and the force of the timer screw return spring 52 in the low pressure chamber C, so that the position of the roller ring 68 is determined and the injection timing is determined. 5 is a pressure regulating valve that controls the pressure in the timer piston high pressure chamber B by changing the opening/closing time ratio by changing the ON/OFF time ratio of the drive pulse from the electric control means 4, and controls the timer piston position, that is, the injection timing. decide. Therefore, the electric control means 4 includes a spill ring position sensor 15 as an injection amount sensor that indirectly detects the injection amount, a cooling water wetness sensor 16 that detects the warm-up state of the engine, and the amount of air taken into the engine. When the detection signals indicating the operating conditions from the intake air temperature sensor 17 and the intake pressure sensor 18 are inputted to calculate the target combustion timing most suitable for the operating conditions of the engine, the actual combustion timing and the target combustion timing are calculated. The timer piston 51 is moved by determining the error with the combustion timing, changing the opening time of the pressure regulating valve 57 according to this error value, and controlling the pressure in the timer piston high pressure chamber B, thereby feeding back the injection timing. Control.

Next, a method for calculating the actual combustion timing will be explained with reference to the timing chart shown in FIG. (1) is an output waveform when the crankshaft position is detected by an electromagnetic pickup serving as the crankshaft position sensor 2, and in this embodiment, the case of a four-cylinder engine is illustrated. Jin's signal (&) indicates that the engine crankshaft is 18.
It occurs at the TDO (top dead center) position every time it rotates 0°. (
b) is the output signal (&) of the crank shirt F position sensor 2
is a signal whose waveform has been shaped by the waveform shaping circuit 42. (
C) is an output signal of the phototransistor of the photodetector 3 that detects the actual combustion timing, and detects the timing when fuel is injected into the IJ cylinder and starts to burn. (d) is an output waveform obtained by shaping the output signal of the photodetector 3 by the waveform shaping circuit 42. The signals (b) and (d) above are sent to the CPU 41
is applied to the input boat and the combustion timing is calculated.

If a one-chip microcomputer is used as the microcomputer, the circuit block diagram of FIG. 8 shows the CPU 41. Memory ILOM44 and memory RA
MA3 is composed of one chip. For example, the circuit number MBL6801W2 made by Fujitsu can be applied, and in that case, the waveform-shaped output signal of the crankshaft position sensor 2 is sent to the input capture register #l,
This can also be realized by configuring the waveform-shaped output signal of the photodetector 30 to be applied to the implant capture register 2. In other words, (d) if the rising edge of the signal is earlier than the rising edges of both signals by T1 time, Tm = (180XT,)/
The angle is advanced by T degrees determined by 'I'N degrees. Here, T is the actual combustion timing, and TN is the time required for the engine link crankshaft to rotate 1/2, that is, to rotate the rotation plate 180 degrees. (If the rise of both signals is 12 hours later than the rise of signal (b), then T = (lsoxT)
/ T The actual combustion timing is determined as a retard angle of N degrees.

Here, the method for calculating the actual combustion timing in the case of retardation is (d
Since the ) signal is generated later than the (b) signal, when the time difference between the (d) signal and the (b) signal is measured as in the case of advance angle, T, / is measured. Therefore, when a value extremely larger than the actual engine advance angle amount is calculated, the calculation T,=Tx-T,' is performed to obtain T,7 as a retardation value. In other words, if the engine's advance angle is a crank angle of up to 10 degrees and the advance angle is a maximum of 3 degrees, then in the case of a retard, Ill, /9Tm is a value close to 180 degrees, which is the value that is actually used. Since this is not the value to be obtained, set a certain setting value, for example, Ts=lo'''r,
In the case of '>'I's, the calculation of T,=Ta-T,' is performed to calculate the actual combustion timing as a retard. The method described above applies when the crankshaft position signal is detected at the TDC of the engine.

Next, as another method for calculating the actual combustion timing, a method will be described in which the crankshaft position signal is generated on the retard side, which is wider than the value that can actually be obtained from the TDC of the engine. In other words, if the maximum amount of retardation is 3 degrees in practice, if the configuration is configured so that it occurs at 10 degrees on the retard side, only T1 will be measured at all times.
)7"'I'N) The actual combustion timing is determined at -10 degrees.If the value of T1 is read in a value outside the range of the set value, which is set with a margin within the practical value, , it is assumed that some abnormality has occurred in the control system or a malfunction due to outer thread noise, and the value is ignored and 1.
Control is performed using the previous value, or in the case of continuous occurrence, a certain fixed value is calculated as a diagnosis (self-diagnosis) and fail-safe processing.

Next, the operation of the apparatus having the above structure will be explained with reference to the diagram shown in FIG. In step lO, in order to calculate the engine rotation speed Hz, NI:6o/(TNX
2) Find r pm.

In step 10g, an engine operating state signal is read. That is, the injection amount signal QT from the spill position sensor as the injection amount sensor 15, the engine cooling water temperature sensor 1
The water temperature signal from 6, the intake temperature signal from intake temperature sensor 17, and the intake pressure signal from intake pressure sensor 18 are subjected to M/D conversion by A/D converter 48, and are stored in the corresponding RAM 45.

In step 10B, four known points O, I are selected from the three-dimensional map of the basic combustion timing based on the engine speed NB and the injection amount QT.
The basic combustion timing Tm is determined by Il type interpolation calculation. Figure 7 shows an example of a basic combustion timing map. tmm is the basic combustion timing data at the grid point. Next, the intake air density is corrected based on the intake pressure and the intake air temperature, and the water temperature is corrected based on the engine cooling water temperature to calculate the target combustion timing TM.

In step 104, the actual combustion timing Tm is calculated from the crankshaft position signal and the actual combustion signal using the method described above. In step 106, an error Tx l IL:TM-Tm is calculated from the target combustion timing TM obtained in step 10B and the actual combustion timing Tm obtained in step 104. Determine whether it is positive or negative. If T bi > Tmu, then T phoenix L〉0
Then, jump to step 109 and set the duty.
By increasing the ratio and increasing the OFF time of the pressure regulating valve 67, the position of the timer piston 51 is moved to the advance side. Also T
If M<Tum, T 11 (becomes O, jumps to step 108, reduces the duty ratio, and turns off the pressure regulating valve 6).
The time is decreased and the position of the timer piston 51 is moved to the retard side. When TM=Tm, Tl1lIL=O, and the duty ratio outputs the same value as the previous time. In other words, if the actual measured value T is lower than the target value TM, the regulating valve 57 increases the OFF time so that the timer piston high pressure chamber B
The pressure is increased and the timer piston 51 is moved to the advance side to advance the combustion timing, that is, the injection timing, so that it matches the target value.

Steps 101 to 109 for each pressure regulating valve control cycle below
Repeat the process.

It should be noted that various structures other than those described above can be used as the photodetector 3. For example, the light from the combustion chamber is guided to a predetermined position by an optical fiber, etc., and then light-to-electrical light conversion is performed. You can also do this.

As described above, the present invention detects the timing when fuel injected into the cylinders of an engine actually starts to burn using a photodetector as an electrical signal, and calculates the timing according to detection signals from various operating state detectors. In order to detect an error with respect to the target combustion timing and control the actual value of the combustion timing to match the target value by the injection timing adjustment means according to the error,
It is possible to accurately achieve the set combustion timing, that is, injection timing, without being affected by variations in the engine and fuel injection system, changes over time, variations in compression ratio, or differences in fuel properties, achieving both exhaust purification and fuel consumption reduction. There is an excellent effect that can be done.

[Brief explanation of the drawing]

FIG. 1 is a pull diagram showing the overall configuration of an embodiment of the present invention, and FIG. 1 is a structural explanatory diagram showing an example of the photodetector in FIG. 1.
FIG. 8 is a configuration diagram showing an example of the electrical calculation means in FIG. 1;
Fig. 4 is a structural explanatory diagram of the injection timing joint means when the present invention is applied to a distribution type fuel injection pump, Fig. 5 is a timing chart illustrating the method of calculating the actual combustion timing, and Fig. 6 is the electrical calculation means. A flowchart showing the processing steps in
Fig. 7 is a diagram showing a two-dimensional map of basic combustion timing. Electrical control means, b... Injection timing adjustment means, 6... Injection bonder, γ
・-Diesel engine, 14...Photofungistar,
15...Injection amount sensor, 16...Cooling water temperature sensor,
17... Intake temperature sensor, 18... Intake pressure sensor, 4
1...CPU. 44...Memory ROM% 4S...Memory RAM%
46...ff1llll path, 51... timer piston, 57-... pressure regulating valve. Representative Patent Attorney Takashi Okabe's ■Toyota 4th Figure 5 1"1 Figure 7 Nn-I Nn Nn+I NE->Continued from Figure 6, Page 1 Within Toyota Motor Corporation Applicant Toyota Motor Corporation 1 Toyota-cho, Toyota City

Claims (1)

[Claims] An operating state detector that detects the operating state of the internal combustion engine, an injection timing adjustment means that adjusts the timing of fuel injection into the engine by the fuel injection cylinder, and a timing when the fuel injected into the cylinders of the engine actually starts to burn. A target combustion timing is calculated based on the detection signal of the operating state detector, and the actual combustion timing detector detects the target combustion timing using the light generated during combustion. 2. A fuel injection timing control device comprising: an electric control means for controlling the injection timing adjustment means so as to correct an error from the actual combustion timing detected by the fuel injection timing control means.