JPH066924B2 - Method of controlling injection quantity of electronically controlled diesel engine - Google Patents

Description

Detailed Description of the Invention [Industrial applications]

The present invention relates to a method for controlling an injection amount of an electronically controlled diesel engine, and particularly suitable for use in a diesel engine for a vehicle equipped with a fuel injection pump of a solenoid valve spill type,
The fuel injection amount is controlled by an electromagnetic spill valve that is controlled to open and close according to the angle count and time count of the engine rotation angle signal, with the engine rotation angle signal output for each constant crank angle as a reference. The present invention relates to an improvement in an injection amount control method for an electronically controlled diesel engine.

2. Description of the Related Art In recent years, with the development of electronic control technology, particularly digital control technology, a so-called electronically controlled diesel engine that electronically controls a fuel injection pump of the diesel engine has been put into practical use. There are various methods of electronically controlling the fuel injection pump, and one of them is a so-called solenoid valve spill type fuel injection pump in which the fuel spill in the fuel injection pump is controlled by a solenoid valve. In this solenoid valve spill type fuel injection pump, the spill port is opened by the solenoid spill valve at the spill timing when the fuel injection amount reaches the target value, and the fuel injection amount is controlled by controlling the end of the pressure feeding of the fuel. To control. The electromagnetic spill valve is normally controlled to open and close by a control device which takes in a detection signal from an engine rotation sensor for detecting an engine rotation angle and a rotation speed and calculates and determines a fuel injection amount based on the rotation angle signal. ing. Specifically, since the injection amount is controlled by the rotation angle of the face cam corresponding to the plunger lift, a gear rotating in synchronization with the face cam is detected by the engine rotation sensor to calculate the rotation angle. In this case, if the number of engine rotation pulses output from the engine rotation sensor is infinite and the rotation angle can be determined only by the number of pulses, precise injection amount control is possible, but the number of pulses cannot be increased infinitely. Actually impossible, the angle per tooth is 11.25 °
The reality is that it is set to CA. Therefore, in the calculation of the rotation angle, the number of teeth is counted from the reference position, and between the teeth, the angle is converted into time and the time is counted. This time conversion is performed on the basis of the time required for rotation of a set crank angle, for example, 180 ° CA, and it is best to use the time at the time of spilling for 180 minutes of this 180 ° CA. Since it is impossible, the value calculated last time will be used.

[Problems to be Solved by the Invention]

Therefore, the angle → time conversion is not performed accurately, and especially when the number of teeth is small and the tooth-to-tooth spacing is long, the time count part with low accuracy becomes long and the accuracy of injection amount control deteriorates. Had. This is remarkable when the rotation speed is large and the rotation speed at the time of actual spilling and the previous average rotation speed often differ from each other at low rotation speeds. Therefore, the injection amount cannot be precisely controlled, the rotation fluctuation further increases, and the engine vibration increases. In order to solve such a problem, it is possible to increase the number of teeth of the rotation angle gear that rotates in synchronization with the face cam, but this gear needs to be housed in the fuel injection pump, and therefore, it is limited. Cutting a large number of teeth on the circumference of the diameter was difficult in terms of work and mass production. One of the applicants was already in Japanese Patent Application No. Sho 59-104949.
It has been proposed to improve the detection accuracy of the rotation angle by arranging a large number of magnetic poles having different polarities next to each other on the circumference, but there is a problem that the cost becomes high. On the other hand, as the one related to the present invention, the applicant has already filed Japanese Patent Application No. 58-232573, and based on a plurality of cycles of the detection signals sequentially generated when the rotation speed is below a predetermined value,
An inflection point at which the rotation speed of the engine turns from deceleration to acceleration is determined, and a reference position detection device is proposed in which the point is set as a reference position, which is the reference position in the engine rotation pulse. This is for the purpose of preventing erroneous detection of, and does not directly improve the control accuracy of the injection amount as in the present invention.

[Object of the Invention]

The present invention has been made to solve the above-mentioned conventional problems, and improves the accuracy of injection amount control by using a rotary angular gear having the same number of teeth as the conventional mass-producible teeth and a relatively inexpensive computer. Therefore, it is an object of the present invention to provide an injection amount control method for an electronically controlled diesel engine, which can obtain smooth rotation with less engine vibration.

[Means for solving problems]

The present invention controls a fuel injection amount by an electromagnetic spill valve that is controlled to open and close according to an angle count amount and a time count amount of the engine rotation angle signal on the basis of an engine rotation angle signal output at every constant crank angle. In the injection amount control method for the electronically controlled diesel engine,
As shown in the outline of the figure, a procedure for determining whether or not the engine rotation fluctuation is a problem in a low engine speed range except when the engine is started, and the rotation angle signal other than the operation range is determined. The procedure for determining the opening and closing timing of the electromagnetic spill valve by counting the time of the spill angle starting from the edge of either the rising edge or the falling edge, and, on the other hand, in the operating region where rotational fluctuation becomes a problem, The above object is achieved by including a procedure for determining the opening / closing timing of the electromagnetic spill valve by counting the time of the spill angle starting from both the rising edge and the falling edge of the signal.

[Action]

In the present invention, the fuel injection amount is controlled by the electromagnetic spill valve that is controlled to open and close according to the angle count and time count of the engine rotation angle signal with reference to the engine rotation angle signal output for each constant crank angle. When performing control, in an operating region where fluctuations in the engine rotation are a problem, the opening / closing timing of the electromagnetic spill valve is determined by counting the time of the spill angle starting from both the rising edge and the falling edge of the rotation angle signal. I have to. Therefore, in the operating region where the rotation fluctuation is a problem, the angle count can be doubled to improve the control accuracy, and the cost is not increased. On the other hand, in the operating region where the rotation fluctuation does not pose a problem, the spill angle is counted from the rising edge or the falling edge of the rotation angle signal as in the conventional case, and the spill angle of the electromagnetic spill valve is opened / closed. Is decided. In the present invention, the operating range in which the rotation fluctuation is a problem,
The operating range is the low engine speed range except when the engine is started. In such an operating region where the rotation fluctuation is a problem, both the rising edge and the falling edge are used, so that the frequency of occurrence of the rotation angle signal is doubled and the time count term is reduced, so that the prediction term is reduced. It is possible,
The control accuracy of the injection amount is improved. On the other hand, in the middle-high rotation range where the increase in the processing amount of the computer is a problem, the same control as the conventional one is performed, so that the calculation time can be sufficiently secured and it is not necessary to upgrade the computer.

【Example】

An embodiment of an electronically controlled diesel engine for a vehicle, in which an injection amount control method according to the present invention is adopted, will be described in detail below with reference to the drawings. In this embodiment, as shown in FIG. 2, an intake air temperature sensor 12 is provided downstream of an air cleaner (not shown) for detecting the temperature of intake air. Downstream of the intake air temperature sensor 12, a turbocharger 14 including a turbine 14A that is rotated by the heat energy of exhaust gas and a compressor 14B that is rotated in conjunction with the turbine 14A is provided. The upstream side of the turbine 14A and the downstream side of the compressor 14B of the turbocharger 14 are communicated with each other through a waste gate valve 15 for preventing the intake pressure from rising too much. On the bench lily 16 on the downstream side 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 accelerator position sensor 20 detects an opening degree (hereinafter, referred to as an accelerator opening degree) Accp of the accelerator pedal 17. 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 through 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,
The engine fuel chamber 10B is provided with an injection nozzle 34, a glow plug 36, and an ignition timing sensor 38, the tip of which faces the engine fuel chamber 10B. 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 drive shaft 42A that is rotated in conjunction with the rotation of the crankshaft of the diesel engine 10 and a feed pump 42B (90 in FIG. 2) fixed to the drive shaft 42A for pressurizing fuel. ° C), a fuel pressure adjusting valve 42C for adjusting the fuel supply pressure, and a gear 4 fixed to the drive shaft 42A.
From 2D rotational displacement to a reference position, eg top dead center (TDC)
For detecting the engine rotation angle and the number of revolutions of the engine from the rotational displacement of a reference position sensor 44 formed of, for example, an electromagnetic pickup, and a gear (rotation angle gear) 42E also fixed to the drive shaft 42A. The engine rotation sensor 46 consisting of a pickup and the face cam 4
A roller ring 42H for reciprocating the 2F 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 ° expanded state). And a timing control valve (hereinafter TC) for controlling the injection timing by controlling the position of the timer piston 42J.
48) and an electromagnetic spill valve 50 for controlling the fuel injection amount by changing the fuel escape timing from the plunger 42G via the spill port 42K.
A fuel cut valve 52 for cutting the fuel when the engine is stopped and an abnormality, and a delivery valve 42L for preventing the backflow of the fuel and the backward dripping are provided. The gear 42E has a plane shape as shown in FIG. 3, for example. 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,
An electronic control unit (hereinafter referred to as ECU) includes a reference position sensor 44, an engine rotation sensor 46, a glow current sensor 54 for detecting a glow current flowing through the glow plug 36, an air conditioner switch, a neutral safety switch output, and a vehicle speed signal. ) 56 is input and processed,
According to the output of the ECU 56, the VSV 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. 4, 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 control program, various data, etc.). 56B, a random access memory (hereinafter referred to as RAM) 56C for temporarily storing operation data and the like 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 air 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.
Multiplexer (hereinafter MP
56K, an analog-digital converter (hereinafter referred to as an A / D converter) 56L for converting an analog signal of the MPX 56K output to a digital signal, and an output of the A / D converter 56L to the CPU 56A. Via the input / output port 56M for taking in the input, the starter signal input via the buffer 56N, the air conditioner signal input via the buffer 56P, the torque converter signal input via the buffer 56Q, and the waveform shaping circuit 56R. I / O port 56S for taking in the ignition timing sensor 38 output and the like input to the CPU 56A, and the waveform shaping for taking the waveform of the ignition timing sensor 38 output and taking it directly into the input interrupt terminal of the CPU 56A. The circuit 56R and the output of the reference position sensor 44 are subjected to waveform shaping and are connected to the same input interrupt terminal of the CPU 56A. Waveform shaping circuit 56T for writing set
And a waveform shaping circuit 56U for shaping the output of the engine speed sensor 46 and directly taking it into another input interrupt terminal of the CPU 56A, and driving the electromagnetic spill valve 50 according to the calculation result of the CPU 56A. Drive circuit 56V for driving the TCV 48 according to the calculation result of the CPU 56A, and the fuel cut valve 52 according to the calculation result of the CPU 56A.
And a common bus 56Y for connecting the respective constituent devices to transfer data and instructions. The operation of the embodiment will be described below. The determination of the fuel injection amount, that is, the spill angle in this embodiment is executed according to the routine in the main routine as shown in FIG. That is, first, in step 110, the spill angle ANGsp for opening the electromagnetic spill valve 50 is calculated from the engine speed Ne obtained from the output of the engine rotation sensor 46 and the accelerator opening Accp obtained from the output of the accelerator position sensor 20. To do. Next, the routine proceeds to step 112, where a double-precision flag set when the engine speed Ne is in the low speed range of 1200 rpm or less excluding the extremely low speed range of less than 400 rpm is set by the engine speed input interrupt routine to be described later. It is determined whether X2 is set. If the judgment result is negative,
In step 114, the spill angle ANGsp is divided by the angle per tooth of the rotary angle gear 42E, for example, 11.25 °, as shown in the following equation, as in the conventional case. Calculate the count term Csp, then
The remainder of this calculation result is converted into the time count term Tsp of the spill angle using the time T180 from the previous reference position, that is, the tooth-missing position, and this routine is exited. On the other hand, when the determination result of the above-mentioned step 112 is positive and it is determined that the control with the starting point of both the rising edge and the falling edge of the rotation angle signal as the starting point is necessary, step 11
6, the spill angle ANGsp is given by
An angle count term Csp of the spill angle is calculated by dividing by an angle per 1/2 tooth of the rotation angle gear 42E, for example, 5.625 °, and then the remainder of the calculation result is
Using the time T180 from the previous missing tooth position, the time is converted into the time count term Tsp of the spill angle, and this routine is exited. ANGsp / 5.625 → Csp + remainder (3) Remainder × T180 / 32 → Tsp (4) On the other hand, from the engine rotation sensor 46 to the waveform shaping circuit 5
The processing according to the engine rotation sensor output pulse input via 6U is executed according to an engine rotation input interrupt (ICAP) routine as shown in FIG. That is, every time a pulse is input from the engine rotation sensor 46, the step 210 is entered to increment the engine rotation pulse interrupt counter Cnirq. Next, in step 212, it is determined whether or not the count value of the counter Cnirq is equal to the angle count term Csp of the spill angle obtained in the preceding step 114 or 116. This step 2
The determination of 12 is basically to determine whether or not there is a spill time before the next engine rotation interruption. When the determination result of step 212 is positive and it is determined that there is a spill timing, the routine proceeds to step 214, where the spill angle of the preceding step 114 or 116 is obtained at the current interrupt time Tint as shown in the following equation. Time count term T
Put the value with sp added in the output register OCR and use it as the spill reference. Tint + Tsp → OCR (5) After the end of step 214 or when the result of the determination in the previous step 212 is negative, the process proceeds to step 216, and it is determined whether or not the input edge selection flag XIedg is set. . If the determination result is positive, that is, if it is determined to be a rising interrupt, the routine proceeds to step 218, where the engine rotation pulse rising interrupt counter Cnirq ₁
Is incremented. When the double precision flag X2 is reset and the engine is running at high speed, the contents of the engine rotation pulse rising interrupt counter Cnirq ₁ match the contents of the engine rotation pulse interrupt counter Cnirq. After the step 218 is completed, or if the result of the determination in the above step 216 is negative, the process proceeds to step 220, and it is determined whether or not it is the missing tooth position corresponding to the reference position. When the determination result is positive and it is determined that the reference position is reached, the routine proceeds to step 222, where counters Cnirq and Cnirq are counted.
_{When 1} is cleared and at step 224, the time T1 of 180 ° CA from the previous missing tooth position to the current missing tooth position is T1.
The engine speed Ne is calculated using 80. Next, at step 226, the engine speed Ne is 400 rpm.
It is determined whether or not it is a low rotation range of 1200 rpm or less excluding an extremely low rotation range of less than. Here, except for the extremely low rotation speed region of less than 400 rpm, it is not possible to determine whether the first output of the engine rotation sensor 46 is a rising or a falling, and the rotational fluctuation situation does not pose a problem. This is to exclude when the engine is started. On the other hand, the reason for excluding the case where it is higher than 1200 rpm is that the rotation fluctuation does not pose a problem in the medium-high speed rotation range of the engine. If the determination result of the above-mentioned step 226 is positive, the procedure proceeds to step 228, the double precision flag X2 is set, and
Processing is performed based on both the rising edge and the falling edge of the engine rotation pulse. On the other hand, if the determination result of the above-mentioned step 226 is negative, the routine proceeds to step 230, where the double precision flag X2 is reset and the time count starting from only the rising edge of the engine rotation pulse is performed as in the conventional case. To be seen. After completion of the preceding step 228 or 230, or if the determination result of the preceding step 220 is negative, the process proceeds to step 232, and the count value of the rising interrupt counter Cnirq ₁ is electromagnetic spill in preparation for the next opening control. It is determined whether or not the set value at which the valve 50 should be closed, for example, 9 is set.
When the determination result is positive, that is, when it is determined that it is time to close the electromagnetic spill valve 50, step 2
34, and as shown in the following equation, this interrupt time Tint
In the output comparison register OCR, add the margin time α until the interruption calculation is completed to the electromagnetic spill valve 5
Prepare to close 0. Tint + α → OCR (6) After the end of step 234 or if the result of the determination in step 232 is negative, the process proceeds to step 236, and the double precision flag X2 is selected in order to select the edge at the next interrupt. Is set or not. If the determination result is positive, it is an area where both edge interruptions are made, so the routine proceeds to step 238, the input edge selection flag XIedg is inverted, and this routine is ended. On the other hand, if the result of the determination at the previous step 236 is negative and it is determined that the area is an interrupt for rising edges only, the process proceeds to step 240, the input edge selection flag XIedg is set, and an interrupt is generated only for rising edges. The routine ends as it is done. Although not shown, the electromagnetic spill valve 50 is opened and closed at the time set in the output comparison register OCR. FIG. 7 (A) shows an example of the relationship between the output of the conventional engine rotation sensor, the spill angle, the angle count term, and the time count term, which are similar to those of the conventional engine rotation sensor, at the time of middle and high speed rotation in this embodiment. Further, FIG. 7B shows an example of the relationship among the output of the engine rotation sensor, the spill angle, the angle count term, and the time count term at low speeds except when the engine is started in this embodiment. As is clear from the figure, in the operating region where the rotational fluctuation becomes a problem, the time count term becomes small, so that the injection amount control accuracy is improved. On the other hand, in the middle-high speed region, the same control as the conventional one is performed, so that a sufficient calculation time is secured and it is not necessary to upgrade the computer. In the present embodiment, the operating range in which the rotational fluctuation is a problem is the low rotational range excluding the extremely low engine speed range, so that the operating range in which the rotational fluctuation is a problem can be easily determined. This extremely low rotation speed range mainly corresponds to when the engine is started. Note that the method of determining the operating region in which the rotation fluctuation is a problem is not limited to this, and it is also possible to determine the engine start time from information other than the engine speed, for example, the starter output.

【The invention's effect】

As described above, according to the present invention, using the rotary angular gear having the same number of teeth as the mass production and the relatively inexpensive computer, the accuracy of the injection amount control in the necessary operating range can be achieved without cost up. Can be improved. Therefore, there is an excellent effect that it is possible to reduce engine vibration and rotation fluctuation.

[Brief description of drawings]

FIG. 1 is a flow chart showing the gist of a method for controlling an injection amount of an electronically controlled diesel engine according to the present invention, and FIG. 2 shows an 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 plan view showing a rotary angular gear used in the above-mentioned embodiment, and FIG. 4 is a block diagram showing the configuration of the electronic control unit, and FIG. 7 is a flow chart showing a routine in the main routine for calculating the spill angle, and FIG. 6 is a flow chart showing an engine rotation pulse input interrupt routine for processing the output of the engine rotation sensor. (A) and (B) are diagrams showing comparative examples of the relationship between the engine rotation pulse, the spill angle, the angle count term, and the time count term at the time of middle-high speed rotation and low-speed rotation in the above embodiment. That. 10 ... Diesel engine, 42 ... Injection pump, 42E ... Gear (rotation angle gear), 46 ... Engine rotation sensor, 50 ... Electromagnetic spill valve, 56 ... Electronic control unit (ECU), Ne ... Engine speed, ANGsp ... Spill angle , Csp ... angle count term, Tsp ... time count term, X2 ... double precision flag, XIedg ... input edge selection flag.

Claims (1)

[Claims] 1. A fuel injection amount is controlled by an electromagnetic spill valve whose opening and closing is controlled according to an angle count and a time count of the engine rotation angle signal with reference to an engine rotation angle signal output at every constant crank angle. In the injection amount control method for an electronically controlled diesel engine to be controlled, a procedure for determining whether or not it is an operating region of an engine low rotation range except when the engine is started, in which engine rotation fluctuation becomes a problem, and the operation In areas other than the range, there is a procedure for determining the opening / closing timing of the electromagnetic spill valve by counting the time of the spill angle starting from either the rising edge or the falling edge of the rotation angle signal, and on the other hand, the rotation fluctuation becomes a problem. In the operating region, the spill angle time is counted from both the rising edge and the falling edge of the rotation angle signal to determine the opening / closing timing of the electromagnetic spill valve. Procedures and the electronic control diesel engine injection control method which comprises a stipulated.