JPS6267246A - Injection quantity control method of electronic control diesel engine - Google Patents

Abstract

PURPOSE:To make it possible to control the injection quantity in the transisting condition most adequately in a simple program, by correcting the average engine speed this time with the difference from the previous average engine speed and with the correcting value responding to the previous injection completion time. CONSTITUTION:The difference DNE between the average engine speed this time and the previous average engine speed is found in computing from the specific time in 180 deg.CA (crank angle) depending on the output of a crank angle standard sensor 44 is stored in ECU 56 in a specific timing. Then a correcting coefficient is found from the relation stored beforehand in the ROM of ECU 56 depending on the value of the spill command time computed previously. The average engine speed for determining the spill time this time is determined by adding the value multiplying the difference DNE of the average engine speed and the correcting coefficient to the average engine speed computed this time. The spill command time is computed depending on this average engine speed and the accelerator opening detected by an accelerator position sensor 20.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to an injection amount control method for an electronically controlled diesel engine, and particularly to an electronically controlled diesel engine for automobiles equipped with a solenoid valve spill type injection pump. The present invention relates to an improvement in an electronically controlled diesel engine injection method suitable for use in which the injection end timing is determined based on at least the engine load and the average engine speed. (Prior Art) In recent years, with the development of electronic control technology, especially digital control technology, so-called electronically controlled diesel engines, in which the injection pump of a diesel engine is electronically controlled, have been put into practical use.Injection pumps There are many ways to electronically control Il, but one of them is the so-called Ti solenoid valve spill method, in which the overflow timing of fuel in the injection pump (hereinafter referred to as spill timing) is controlled by a solenoid valve. There is a pump.In this solenoid valve spill type injection pump, when the fuel injection amount reaches the target value, the spill port is opened by the solenoid spill valve and the fuel is pumped by controlling the fuel pressure path. In an electronically controlled diesel engine using such an electromagnetic spill valve type injection pump, as shown in Fig. 6, the pressure in the plunger chamber is monitored and the spill command is period θsp
By changing the ``It l!'' Q: I'm trying to control DJ Kou Q. On the other hand, the spill command timing θsp is
As shown in FIG. 7, it is calculated using, for example, the average engine speed NE and the engine speed, for example, the accelerator opening fjJ A CC11. Here, the average engine speed N[ is the engine rotation pulse (
The required vI interval between N (hereinafter referred to as pulses) is determined as shown in Fig. 8. Therefore, the average engine speed NE should normally be 0 once for each injection in each cylinder. That is,
In the case of a 4-cylinder engine, 7j is sufficient for 180° CAffi. (Problem to be solved by the invention) However, every 180'CA, the average engine speed N
When calculating F, there is no problem if the engine is in a steady state, but during transients, the difference between the calculated average engine speed NF and the actual average engine speed NE- is calculated, so deceleration is required. Sometimes, as shown in FIG. 9, the average engine speed N[ becomes larger than the actual average engine speed NE-, and as is clear from the above-mentioned FIG. 7, the spill command timing O8
p is calculated a little, and chant 11) + ffi is insufficient,
severe problems) may lead to engine stall. On the other hand, during acceleration, the average engine speed NE is smaller than the sudden average engine speed NE-, so as is clear from FIG. If the amount is too high, the concentration of exhaust black smoke increases. In order to solve this problem, a method of calculating the average engine speed NE@n just before the spill period can be considered, but the calculation of the average engine speed NE has to be done at a constant timing every time in the program. On the other hand, as is clear from Figure 7, the spill command timing θsp changes due to the fact that the maximum 70' CA also changes and the program progresses from the calculation of the average engine speed NE to the spill timing. In practice, it is impossible to always calculate the average engine speed NE immediately before the first spill period due to periodic time delays. Therefore, in the past, the average engine speed NE had to be calculated frequently, for example every 45° CA, which made the equation complicated. [Objective of the Invention] 41 The present invention has been made to solve the above-mentioned conventional problems, and it is possible to calculate the average engine rotation speed, which has the highest load on the program, with a simple program, and further, An object of the present invention is to provide an injection amount control method for an electronically controlled diesel engine that can optimally control injection m even in a transient state. (Means for Solving the Problems) The present invention provides an injection amount control method for an electronically controlled diesel engine in which the injection end timing is determined based on at least the engine load and the average engine speed, as shown in FIG. As shown in the summary, there is a procedure for calculating the average engine rotation speed only once at a fixed timing for each injection in each cylinder, and a procedure for calculating the difference between the previous average engine rotation speed and the current average engine rotation speed. , a procedure for determining a correction value according to the previous injection end time, and the current average engine speed is corrected based on the difference and correction value, and the average engine speed for determining the injection end time is calculated by taking into account the acceleration/deceleration state. The above object is achieved by including a procedure for determining the engine speed.Furthermore, in an embodiment of the present invention, the average engine speed is set to 1.
The timing for calculating the number of injection times is set to 5 to 15° CA before the earliest injection end timing in terms of engine control. Further, in an embodiment of the present invention, when the angle from the calculation timing of the average engine rotation speed to the injection end timing, which is multiplied by the correction value by the difference, is 0' CA, the injection t of each cylinder is 0' CA.
The correction coefficient is set to 1 when the interval is equal to f4. [Operation] In the present invention, when determining the injection end timing based on at least the engine load and the average engine speed,
The average engine speed is calculated only once at a fixed timing for each injection of each cylinder, and the current average engine speed is calculated based on the difference between the previous average engine speed and the current average engine speed and the end timing of the previous injection. The rotational speed is corrected to obtain an average engine rotational speed for determining the injection end timing, taking into account the acceleration/deceleration state. Therefore, the average engine speed becomes a value that reflects the acceleration/deceleration state, and the injection amount can be optimally controlled even in a transient state using a simple graph. The timing for calculating 5 times is set at 5 times from the earliest injection end time under engine control.
If it is set before ~15° CA, the average engine speed can be calculated at the optimal timing. In addition, the correction value is a correction coefficient that is multiplied by the difference and becomes 0 when the angle from the calculation timing of the average engine speed to the injection end timing is 0° CA, and becomes 1 when it is equal to the injection interval of each cylinder. In some cases, the average engine speed can be corrected easily and accurately. (Example) Hereinafter, an example of an electronically controlled diesel engine for automobiles in which the injection M control method according to the present invention is adopted will be described in detail with reference to the drawings. As shown in the figure, an intake air temperature sensor 12 for detecting the temperature of intake air is provided downstream of an air cleaner (not shown). a turbine 14A rotated by thermal energy of the turbine 1;
A turbocharger 14 consisting of a compressor 14B rotated in conjunction with a compressor 4A is provided. The upstream side of the turbine 14A of the turbocharger 14 and the compressor 1
The downstream side of 4B is communicated via a wastegate valve 15 for preventing an excessive rise in intake pressure. The venturi 16 downstream of the compressor 14B includes:
A main intake throttle valve 18 is provided which is configured to rotate non-linearly in conjunction with an accelerator pedal 17 disposed at the driver's seat to reduce the flow rate of intake air to 1 blJ@ during idling. The opening degree A cap of the accelerator pedal 17 (hereinafter referred to as accelerator opening degree) is detected by an accelerator position sensor 20 . 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 10,
An injection nozzle 34 whose tip faces the engine combustion v10B, a glow plug 36, and an ignition timing sensor 38 are provided. Further, the cylinder block 10G of the diesel engine 10 is equipped with a water temperature sensor 40 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 pump drive shaft 42A that rotates in conjunction with the rotation of the crankshaft of the diesel engine 10, and a feed pump 42B (a second pump) fixed to the pump drive shaft 42A for pressurizing fuel. (The figure shows a 90" expanded state), a fuel pressure adjustment valve 42C for adjusting the fuel supply pressure, and the pump drive shaft 42A.
A crank angle reference sensor 44 consisting of, for example, an electromagnetic pickup is used to detect a crank angle reference position, for example, top dead center (TDC>) from the rotational displacement of a pump drive pulley 42D fixed to the pump drive shaft 42A. For example, the engine rotation sensor 46 consisting of an i-pickup, the face cam 42F, and the plunger 42G are reciprocated, and their timing A roller ring 42H for changing the rotational position of the roller ring 42H, a timer piston 42J for changing the rotational position of the roller ring 42H (FIG. 2 shows a state in which it is expanded by 90 inches), and a timer piston 42J for controlling the position of the timer piston 42J. A timing control valve (hereinafter referred to as TCV) 48 for controlling the injection timing by controlling the injection timing, and an electromagnetic valve for controlling the fuel injection amount by changing the timing for releasing fuel from the plunger 42G via the spill boat 42K. The glow plug 36 includes a glow relay 37. A glow current is supplied through 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,
Crank angle base It sensor 44, engine rotation sensor 46,
The glow current sensor 54 that detects the glow current flowing through the glow plug 36, the key switch, the air conditioner switch, the neutral left switch output, the vehicle speed signal, etc. are input to an electronic control unit (hereinafter referred to as ECU) 56 and processed. , the output of the ECU 36 causes the VSV 28.30, glow relay 37, TCV 48, electromagnetic spill valve 50. The fuel cut valve 52 and the like are controlled. As shown in detail in FIG. 3, the ECU 36 includes a central processing unit (hereinafter referred to as CPU) 56A for performing various calculation processes, and a read-only memory (hereinafter referred to as CPU) for storing control programs, each scale data, etc. , a random access memory (hereinafter referred to as RAM) 56B for temporarily storing data such as data in the CPU 56A, a clock 56D for generating a clock signal, and a buffer 56E. The output of the water temperature sensor 40 is input via the intake air temperature sensor 12, the output of the intake air temperature sensor 12 is input via the buffer 56F, and the output of the intake air temperature sensor 12 is input via the buffer 56G.
The output of the intake pressure sensor 32 is inputted via a buffer 56H, and the output of the accelerator position sensor 2 is inputted via a buffer 56H.
A multiplexer (hereinafter referred to as
an analog-to-digital converter (hereinafter referred to as an A/D converter) 56 for converting an analog signal output to the MPX 56 into a digital signal; [Input/output port 56M for inputting output to CPU 56A, starter signal input via buffer 56N, air conditioner signal input via buffer 56P, torque converter signal input via buffer 56Q, waveform shaping The input/output port 56S inputs the ignition timing = 12-sensor 38 output etc. to the CPU 56A via the circuit 56R, and the input/output port 56S for inputting the ignition timing sensor 38 output etc. into the CPU 56A, and the waveform shaping of the ignition timing sensor 38 output to the input interrupt terminal ICAP2 of the CPU 56Δ. The waveform shaping circuit 56R for direct input and the waveform shaping of the crank angle reference sensor 44 output are sent to the CPU 5.
6A, a waveform shaping circuit 56T for direct input to the same input interrupt terminal ICAP2, and the engine rotation sensor 46.
The output is waveform-shaped and sent to the CPU 56 as an NE pulse.
A waveform shaping circuit 56U for direct input to A and front &lC
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, and 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 ht valve 52, and a common bus 56Y for connecting each component to transfer data and commands. Here, the ignition signal output from the waveform shaping circuit 56R is
The reason why it is input not only to the input interrupt terminal ICΔP2 of the PU 56A but also to the input/output port 56S is to distinguish it from the reference position 11ff1 of the output of the waveform shaping circuit 56T that is input to the same input interrupt terminal ICAP2. The effects of the embodiment will be explained below. The calculation of the spill command timing θsp in this embodiment is based on the fourth
It is executed according to the flowchart shown in the figure. That is, first, in step 110, since the NE pulse is, for example, one pulse before the smallest spill command timing θsp for engine control (CNE=O in the embodiment), it is determined whether it is the timing to calculate the average engine speed NE. Determine whether or not. If the determination result is positive, the process proceeds to step 112, where the average engine speed NE is calculated from the time required for 180° OA. Next, the process proceeds to step 114, where the difference DNE between the average engine speed NE evaluated this time and the previous average engine speed NE is determined and stored. Next, the process proceeds to step 116, and according to the previously calculated value of the spill command timing θsp, a relationship as shown in FIG. 5, for example, which is stored in advance in the ROM 56B, is used.
Find the correction coefficient Kn. Then proceed to step 118;
As shown in the following formula, the average engine speed N calculated this time
E, the difference DNE multiplied by the correction coefficient) (n) is added to find the average engine speed NEsp for determining the spill timing, taking into account the acceleration/deceleration state. NEsp←NE+Kn xDNE ----------( 1
) Next, the process proceeds to step 120, in which the above-mentioned seventh
The spill command timing θsp is calculated using the relationship shown in the figure. According to this embodiment, during deceleration, the difference DNE becomes negative and the average engine rotation NEsp for determining the spill command timing becomes larger than the average engine rotation speed NE, so that the spill command timing θ
The sp becomes larger, which can solve the problem of insufficient injection amount during deceleration. On the other hand, during acceleration, the difference DNE becomes positive and the average engine speed NEsc for determining the spill command timing becomes larger than the average engine speed NE, so the spill command timing θsp becomes smaller and the exhaust black smoke during acceleration becomes smaller. can suppress the increase in In this embodiment, the timing at which the average engine speed NE is calculated only once is the pulse immediately before the earliest spill command timing on the engine &+JII.
The average engine speed NE can be calculated at appropriate timing. Note that the timing at which the average engine speed NE is calculated only once is not limited to this. In addition, in this embodiment, the difference DNE between the previous average engine speed and the current average engine speed is added to the average engine speed N determined according to the previous spill command timing θsp.
The angle from the calculation timing of E to the spill command timing is O
”01 Injection interval for each cylinder at OA (180' OA)
Since the current average engine speed NE is corrected by multiplying it by n, the average engine speed NEsp for determining the spill command timing can be easily and accurately calculated. Note that the method of correcting the average engine speed NE according to the difference ONE and the previous spill command timing is not limited to this. Although the present invention was applied to an electronically controlled automotive diesel engine equipped with a turbocharger in which the amount of fuel injection was controlled by the No. It is obvious that the present invention can be similarly applied to a general diesel engine in which the injection end timing is controlled by a control actuator. [Effects of the Invention] As explained above, according to the present invention, The injection amount can be optimally controlled even in transient conditions by using the average engine speed calculated in It has excellent effects such as being able to prevent insufficient injection amount during acceleration and an increase in exhaust black smoke during acceleration.

[Brief explanation of drawings]

FIG. 1 shows an electronically controlled diesel engine according to the present invention. 2 is a sectional view including a partial block diagram showing the overall configuration of an embodiment of an electronically controlled diesel engine for automobiles in which the present invention is adopted. FIG. 4 is a block diagram showing the configuration of the electronic control unit used in the embodiment, FIG. 4 is a flowchart showing a routine for calculating the spill command timing, and FIG. 5 is a flow chart of the routine. Figure 6 shows an example of the relationship between the previous spill command timing and the correction coefficient used in
Figure 7 is a diagram showing an example of the relationship between spill command timing and plunger lift, that is, injection amount; Figure 7 is a diagram showing an example of the relationship between average engine speed, accelerator opening, and spill command timing; The figure is a diagram showing a method of calculating the average engine speed from the engine rotation pulse, and Figure 9 is a diagram showing an example of the relationship between the average engine speed during transient (deceleration) and the actual average engine speed. It is. 10...Diesel engine, 20...Accelerator position sensor, ACCI)...Accelerator opening, 42 ・=・1. FI DI pump, 46... Engine rotation sensor, 50... Electromagnetic spill valve, 56... Electronic control unit (ECU), NE... Average engine speed, DNE... Previous average engine speed The difference this time is 1
(n...Correction coefficient, NE St)...Average engine rotation speed for determining spill command timing, θsp...Spill command timing, Q...Medium tJ1 amount. Agent Takaya Ronmatsu Yama Keisuke

Claims (3)

[Claims] (1) In an injection amount control method for an electronically controlled diesel engine in which the injection end timing is determined based on at least the engine load and the average engine speed, the average engine speed is determined at a constant timing for each cylinder injection. A procedure for calculating the number only once, a procedure for calculating the difference between the previous average engine rotation speed and the current average engine rotation speed, a procedure for calculating a correction value according to the previous injection end time, and a procedure for calculating the difference and correction. An injection amount of an electronically controlled diesel engine, comprising: a step of correcting the current average engine rotation speed based on the current average engine rotation speed and calculating an average engine rotation speed for determining injection end timing, taking acceleration/deceleration conditions into consideration; Control method. (2) Injection in the electronically controlled diesel engine according to claim 1, wherein the timing of calculating the average engine speed only once is 5 to 15 degrees CA before the earliest injection end timing in engine control. Volume control method. (3) The correction value is multiplied by the difference, and is a correction coefficient that is 0 when the angle from the calculation timing of the average engine speed to the injection end timing is 0° CA, and 1 when it is equal to the injection interval of each cylinder. An injection amount control method for an electronically controlled diesel engine according to claim 1.