JPS61187557A - Fuel injection timing control method of diesel engine - Google Patents

Abstract

PURPOSE:To improve the response performance in transient state by largely increasing at least the integration term in feedback control in comparison with the ordinary case when transient state is detected, in the feedback control of the ignition timing according to the deviation between the aimed ignition timing and the actual ignition timing. CONSTITUTION:When the feedback conditions for fuel injection timing are fulfilled, aimed ignition timing is calculated on the basis of each output signal of a revolution speed sensor (not shown in the figure) and an acceleration position sensor 20 in an ECU56. Then the deviation between the aimed ignition timing and the actual ignition timing obtained from the output of an ignition timing sensor 38 is calculated, and the fundamental injection timing calculated beforehand is corrected according to the deviation, and the timer mechanism of an injection pump is controlled according to the corrected injection timing. When it is detected in the above that an engine is in transient state such as acceleration, at least the integration term in feedback control is largely varied in comparison with the ordinary case.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to an injection timing control method for a diesel engine, and in particular, a method for controlling injection timing based on at least engine load and engine rotation speed, which is suitable for use in an electronically controlled diesel engine for automobiles equipped with an ignition timing sensor. Injection timing is fed back 1iI according to the deviation between the target ignition timing and the actual ignition timing detected using the ignition timing sensor.
The present invention relates to an improvement in a diesel engine injection timing control method.

[Prior art I] Japanese Patent Laid-Open No. 57-28842 and No. 58-25 regarding injection timing control for optimizing the exhaust gas purification performance of diesel engines, especially diesel engines for automobiles.
582, JP 58-192935, JP 59-15
3942, etc., an ignition timing sensor such as a flame sensor is installed at the end of combustion, and the ignition timing sensor detects the ignition timing in the downward direction of combustion (when the pressure in the cylinder suddenly rises due to combustion, or when the combustion light due to ignition is detected). By feeding back the detection results of the start-up timing), the actual ignition timing can be adjusted.
It has been proposed to provide feedback to the injection timing so that the required ignition timing is determined by the engine load, engine speed, etc. In such feedback control of the injection timing based on the output of the ignition timing sensor, the signal from the ignition timing sensor is normally adjusted to a certain threshold value vt, as shown by the solid line in FIG.
The waveform is shaped at t+, the actual ignition timing is calculated from the difference between the signal and the reference position, and the duty ratio of the timer control valve is corrected based on the difference between the target ignition timing and the actual ignition timing. (Problems to be Solved by the Invention) However, when the target ignition timing changes rapidly, such as during acceleration, the difference from the actual ignition timing becomes large, so it is necessary to control quickly. In this case, if it is not ignition feedback control but conventional timer position control, for example, 5
The eye of the timer position (jlli
There is no problem if you compare l with the current position, but in ignition feedback control, the previous ignition timing must be used. 1 in rotation
The interval of feedback control based on the ignition timing detected twice is about 150 milliseconds, and in such a transient state, the response will deteriorate unless the feedback gain is increased. On the other hand, in a steady state at high speed, if the gain is too high, the correction becomes too large, causing problems such as unstable injection timing. [Object of the Invention] The present invention has been made in order to solve the above-mentioned conventional problems, and in ignition feedback control, it is possible to improve responsiveness during transient times and to obtain stable injection timing during steady states. The purpose of the present invention is to provide a method for controlling injection timing of a diesel engine. [Means for Solving the Problems] The present invention provides a means for solving the problem according to the deviation between the target ignition timing determined based on at least the engine load and engine speed and the actual ignition timing detected using an ignition timing sensor. In the injection timing control method for a diesel engine that performs feedback control of the injection timing, as shown in Figure 1, there is a procedure for detecting a transient state, and at least an integral term of the feedback control is determined during the transient state. The above objective is achieved by including a step of making the process larger than usual.

[Operation j] In the present invention, depending on the deviation between the target ignition timing determined based on at least the engine load and engine speed and the actual ignition timing detected using the ignition timing sensor,
When performing feedback control i11 on the injection timing, at least the integral term of the feedback control is made larger during transient times than during steady state. Therefore, responsiveness is improved during transient times such as during acceleration, while stable injection timing can be achieved during steady state times. [Embodiment 1] Hereinafter, an embodiment of an electronically controlled diesel engine for automobiles in which the injection timing control method according to the present invention is adopted will be described in detail with reference to the drawings. As shown in FIG. 2, this embodiment includes an intake air temperature sensor 12 disposed downstream of an air cleaner (not shown) for detecting the temperature of intake air. The absorption%'i
A turbocharger 14 is provided downstream of the M sensor 12 and includes a turbine 14A rotated by thermal energy of exhaust gas and a compressor 14B rotated in conjunction with the turbine 14A. The turbocharger 14
The upstream side of the turbine 14A and the downstream side of the compressor 14B are communicated via a wastegate valve 15 to prevent the intake pressure from rising too much. The venturi 16 on the downstream side of the compressor 14B"F" is provided with a venturi for restricting the flow rate of intake air during idle time, etc.
A main intake throttle valve 18 is provided which is configured to rotate non-linearly in movement with an accelerator pedal 17 disposed at the driver's seat. The opening degree of the accelerator pedal 17 (hereinafter referred to as the accelerator opening degree) Accp is determined by the accelerator position sensor 2.
0 has been detected. A sub-intake throttle valve 22 is provided in parallel with the main intake throttle valve 18 , and the opening degree of the sub-intake throttle valve 22 is controlled by a diaphragm device 24 . Negative pressure generated by a 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 valve 18.22. In the cylinder head 10A of the diesel engine 1o,
An injection nozzle 34 whose tip faces the engine combustion chamber 10B, a glow plug 36, and an ignition timing sensor 38 are provided. Further, the cylinder block 10C of the diesel engine 10 is equipped with a water temperature sensor 40ffi for detecting the engine cooling water temperature. Fuel is fed under pressure to the injection nozzle 34 from an injection pump 42 . The injection pump 42 includes a drive shaft 42A that rotates with the rotation of the crankshaft of the diesel engine 10, and a feed pump 42B (FIG. 2 shows a feed pump 42B fixed to the drive shaft 42A for pressurizing fuel). ), a fuel pressure adjustment valve 42G for adjusting the fuel supply pressure, and a gear 4 fixed to the drive shaft 42A.
From the 2D rotational displacement to the reference position, e.g. top dead center (TDC)
A reference position sensor 44 made of, for example, a l1iti pickup, for detecting the engine rotation speed, and an engine rotation speed sensor 46 made of, for example, an electromagnetic pickup, for detecting the engine rotation speed from the rotational displacement of a gear 42E fixed to the drive shaft 42A. , an 0-cylinder 42H for reciprocating the face cam 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 90' unfolded ) and the timer piston 4
By controlling the position of 2J, the injection timing is adjusted to tl
J III timing control valve (hereinafter referred to as TCV)
) 48, and an electromagnetic spill valve 50 for controlling the fuel injection amount by changing the timing at which fuel is released from the plunger 42G via the spill port 42K.
a fuel cut solenoid 52 for cutting fuel;
Delivery valve 4 to prevent fuel backflow and backflow
It is equipped with 2L. A glow current is supplied to the glow plug 36 via a glow relay 37. As shown in detail in FIG. 3, the blue fire timing sensor 38 is
A cylindrical case 38A inserted and fixed into the cylinder head IOA of the diesel engine 1o, a light guide 38B made of quartz glass, for example, inserted into the center of the case 38A for transmitting combustion light, and the light A light receiving element 3 made of, for example, a silicon photodiode, for detecting the light transmitted by the conductor 38B and converting it into an electrical signal.
8C is provided. 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,
Reference position sensor 44, engine speed sensor 46, glow current sensor 54 that detects the glow current flowing to the glow plug 36, air conditioner switch, neutral safety switch output,! lil deviation, etc. are input to an electronic control unit (hereinafter referred to as ECU) 56 and processed, and the output of the ECU 36 determines the VSV28.3.
O, G1]-1J17-37, TCV48.1iffl
Subi/L. The valve 50, fuel cut solenoid 52, etc. are controlled. The ECU 36 is shown in detail in FIG. 4. The central processing unit for performing various arithmetic processing is as follows: C
(hereinafter referred to as PU) 56A, and a read-only memory (hereinafter referred to as RO) for storing control programs and various data.
A random access memory (hereinafter referred to as RAM) 56C for temporarily storing calculation data etc. in the CPU 56A, a clock 56D that generates a clock signal, and a buffer 56E. the water temperature sensor 40 output, the intake temperature sensor 12 output input via the buffer 56F, the intake pressure sensor 32 output input via the buffer 56G,
Buffer 56HJE: A multi-brake buffer (hereinafter referred to as MPX) 56 for sequentially taking in the output of the accelerator position sensor 20 etc. inputted by LL, and a buffer for converting the analog signal output to the MPX 56 into a digital signal. An analog-to-digital converter (hereinafter referred to as A, -'D converter) 56L and the output of the A, -'D converter 56L are converted to C.
Input/output port 56M for input to PU56A, starter signal inputted via buffer 56N, air conditioner signal inputted via buffer 56P, buffer 56
Torque converter signal input via Q, waveform shaping circuit 56
an input/output port 568 for inputting the output of the ship's ignition timing sensor 38, etc. inputted via the CPU 56A;
the waveform shaping circuit 56R for directly inputting the output to the input interrupt terminal fcAP2 of the CPU 56A; and the waveform shaping circuit 56T for shaping the output of the reference position sensor 44 and directly inputting it to the same input interrupt terminal ICAP2 of the CPU 56A; A waveform shaping circuit 56 for waveform shaping the output of the engine rotation speed sensor 46 and directly importing it into the CPtJ56A.
a drive circuit 56V for driving the electromagnetic spill valve 50 according to the calculation result of the CPU 56A; a drive circuit 56W for driving the TCV 48 according to the calculation result of the CPU 56A; It is comprised of a drive circuit 56X for driving the fuel cut solenoid 52 according to the calculation result, and a common bus 56Y for connecting each component to transfer data and instructions. Here, the ignition signal output from the waveform shaping circuit 56R is
The reason why this signal is input not only to the input interrupt terminal ICAP2 of the PU 56A but also to the input/output port 56S is to distinguish it from the reference position signal output from the waveform shaping circuit 56T that is input to the same input interrupt terminal ICAP2. The effects of the embodiment will be explained below. Injection timing control in this embodiment is executed according to a flowchart as shown in FIG. That is, step 1 is executed every certain period of time, for example, 50 milliseconds.
10, the basic injection timing T[) base is calculated from, for example, the engine speed Ne and the accelerator opening A cap. Next, the process proceeds to step 112, where it is determined whether a feedback condition is satisfied based on, for example, the operating state (deceleration or absence) and the presence or absence of an ignition signal. If the determination result is negative, the process proceeds to step 114, and the basic injection timing TDb
Ase is the control duty ratio of TCV48 [)u
ty, this routine ends. On the other hand, if the determination result in step 112 is positive, the process proceeds to step 116, where the target ignition timing T Ra ta is calculated from the engine speed Ne and the accelerator opening degree ACp. The target ignition timing T RG ig is, for example, advanced from the ignition timing corresponding to the basic injection timing T D base. Next, the process proceeds to step 118, where the gA difference ΔIG between the target ignition timing T RG ig and the actual ignition timing ACTi determined from the output of the ignition timing sensor 38 is calculated as shown in the following equation. Δ ta=r RG + ACTi... (1)
Next, the process proceeds to step 120, in which an integral term Di and a proportional term Do are calculated for feedback control tIlV of the injection timing, as shown in the following equation, according to the determined deviation Δi. Dr-f(ΔIGn......
・ ... (2>Di-g (Δ rG)
(3) The integral term Di and the proportional term Do have a relationship with the deviation ΔIG as shown in FIG. 6, for example. Next, the process proceeds to step 122, where it is determined in another routine whether or not the vehicle is in an acceleration state based on, for example, the amount of depression of the accelerator pedal, that is, the differential value of the accelerator opening degree ACCD. If the determination result is positive, the process proceeds to step 124, where the integral term Qt obtained in step 120 is multiplied by 4 as shown in the following equation and is set as a new integral term Di. Di −Di X4 ・・・・・・・・・(
4) After the completion of step 124, or when the judgment result of step 122 is negative and it is judged that the acceleration state is not present, the process proceeds to step 126, and the basic injection timing TDbaSe is adjusted by the integral term Qi and the proportional term as shown in the following equation. By adding the term Dp, the control dignity ratio of TCV48 □
Find uty and end this routine. Duty −TDbase+Di +[)p = (5
) In this way, by setting the integral term Di of the feedback control during acceleration to four times the value of the steady state, responsiveness during acceleration can be improved without deteriorating the stability during steady state. In this embodiment, only the integral term D1 is increased during acceleration, so that the response can be improved for a relatively long period of time in a region where the proportional term Dp does not act in the dead zone, which is effective. Corrections can be made to In addition,
Methods to improve responsiveness during acceleration are not limited to this,
For example, it is also possible to increase the proportional term Dp together with the integral term DI. In the above embodiment, the acceleration state is detected from the differential value of the amount of depression of the accelerator pedal, but the method of detecting the acceleration state is not limited to this. Further, in the above embodiments, the present invention was applied to improving responsiveness during acceleration, but the scope of application of the present invention is not limited to this, and response can be similarly improved in transient states other than during acceleration. can improve sexual performance. In the embodiment described above, the engine load was detected from the accelerator opening degree A ccp output from the accelerator position sensor 20, but the method for detecting the engine load is not limited to this. In the embodiment described above, the present invention was applied to a supercharged diesel engine in which the fuel injection amount was controlled by the electromagnetic spill valve 50, but the scope of application of the present invention is not limited to this. It is clear that the present invention can be similarly applied to general diesel engines equipped with fuel injection amount control actuators other than electromagnetic spill valves. EFFECTS OF THE INVENTION As explained above, according to the present invention, there is an excellent effect that responsiveness during transient times can be improved without impairing stability during steady state.

[Brief explanation of drawings]

FIG. 1 is a flowchart without showing the gist of the injection timing control method for a diesel engine according to the present invention. FIG. Sectional view including part block diagram, 3rd
The figure is a vertical cross-sectional view showing the configuration of the ignition timing sensor used in the above embodiment, FIG. 4 is a block diagram similarly showing the configuration of the electronic side unit, and FIG.
Flowchart showing routine for controlling injection timing, No. 6
The figure is a flow chart showing an example of the relationship between the deviation between the target ignition timing and the actual ignition timing, and the integral term and the proportional term used in the routine, and Fig. 7 is a line showing an example of the output signal of the ignition timing sensor. It is a diagram. DESCRIPTION OF SYMBOLS 10... Diesel engine, 17... Accelerator pedal, 2o... Accelerator position sensor, A ccp... Accelerator opening degree, 34... Injection nozzle, 38... Ignition timing sensor, 42... Injection pump, 42J...Timer piston, 44...Reference position sensor, 46...Engine speed sensor, Ne...Engine speed, 48...Timing control valve (TCV), 56... Electronic control unit (ECU), TDbaSe...basic injection timing, TRG io...target ignition timing, ACTi...actual ignition timing, ΔIG...deviation, outy...control duty ratio .

Claims (1)

[Claims] (1) A diesel engine that performs feedback control of the injection timing according to the deviation between the target ignition timing determined based on at least the engine load and engine speed and the actual ignition timing detected using an ignition timing sensor. An injection timing control method for an engine, comprising: a step of detecting a transient state; and a step of making at least an integral term of feedback control larger during a transient state than during a steady state. Method.