JPH063166B2 - Method of controlling injection quantity of electronically controlled diesel engine - Google Patents

Description

Detailed Description of the Invention

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.

[Prior art]

2. Description of the Related Art In recent years, with the development of electronic control technology, particularly digital control technology, 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 electromagnetic spill type fuel injection pump in which fuel spill in the fuel injection pump is controlled by a solenoid valve. In this solenoid valve spill type fuel injection pump, when the fuel injection amount reaches the target value, the spill port is opened by the electromagnetic spill valve to control the end of the pressure feed of the fuel, thereby controlling the fuel injection amount. To do. 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, as shown in FIG.
The rotation angle was calculated by detecting the gear that rotates in synchronization with the face cam with the engine rotation sensor. 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. In reality, this is impossible, and the reality is that the angle per tooth is set to 11.25 ° CA. Therefore, the rotation angle (spill angle ANGsp) is calculated by counting the number of teeth from the reference position (missing tooth position) (angle count term Csp), and between the teeth, the angle is calculated as time. Is converted to and the time is counted (time count term Tsp). This time conversion is based on the set crank angle, for example 4
The time T45 required for rotation of 5 ° CA is used as a reference. For this time T45 of 45 ° CA, it is best to use the time at the time of spill, but since it is impossible, the value calculated previously (average value) 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 distance between the teeth is long, the time count with low accuracy becomes longer and the accuracy of the injection amount control decreases. Had. This is because the rotation fluctuation is large,
This is remarkable when the engine speed is low and the previous engine speed is often different from the actual engine speed. 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 increase the detection accuracy of the rotation angle by arranging a large number of magnetic poles having different polarities side by side on the circumference, but there is a problem that the cost becomes high. On the other hand, as related to the present invention, the applicant has already filed Japanese Patent Application No. 58-232573, in which the rotation speed of the engine is decelerated based on a plurality of cycles of detection signals which occur sequentially when the rotation speed is below a predetermined value. A reference position detection device is proposed, in which an inflection point at which the speed changes to an increased speed is obtained, and that point is used as a reference position. This is the reference position (partial tooth position) of the engine rotation pulse. This is to prevent erroneous detection, 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 it is possible to improve the accuracy of injection amount control by using a rotary angular gear having the same number of mass-producible teeth as the conventional one. An object of the present invention is to provide an injection amount control method for an electronically controlled diesel engine capable of obtaining 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 from the gist thereof in the drawing, to calculate the last spill previous settings crank Kakuma engine rotation time _{T n-1, i-1} , a step of storing, this spill previous settings crank Kakuma engine rotation time T _{n, i- Using} the procedure for calculating ₁ and the value T _{n-1, i-1} immediately before the previous spill and the value T _{n, i-1} immediately before the current spill of the engine rotation time between the set crank angles, the set crank at the current spill is used. a step of predicting calculate Kakuma engine rotation time T _{n, i,} the predicted set crank Kakuma engine rotation time of the current time of the spill T _n, with _i, by including a procedure for time conversion of the spill angle, The above object is achieved. According to the embodiment of the present invention, the engine rotation time Tn _{, i} between the set crank angles during the current spill is set to the engine rotation time T between the crank angles before the previous spill value of the immediately preceding cylinder.
_{n-1, i-1} and the engine rotation time T _{n, i-1} between the set crank angles immediately before the current spill and the engine rotation time T _{n-1, i} between the set crank angles during the previous spill of the cylinder are used to calculate T _{n, i} = T _{n-1, i} × Tn, _i-1 / T _n-1 , _i-1 (1) The prediction crank calculation is performed according to The engine rotation time can be accurately predicted.

[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. in controls, set crank Kakuma value of the last spill immediately before the engine rotation time T _{n-1, i-1} and the value T _n of this spill _immediately before using the _i-1, setting the crank Kakuma engine rotational time during this spill T _{n, i} is predicted and calculated, and the predicted spill angle engine rotation time during the current spill is used to perform time conversion of the spill angle. Therefore, it is possible to perform time conversion with high accuracy and to improve the accuracy of injection amount control, as compared with the case where an old engine rotation time is used as in the conventional case. Therefore, the rotation fluctuation is large,
According to the conventional method, smooth rotation with less engine vibration can be obtained even in a low rotation region where engine vibration is large.

【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 for detecting the temperature of intake air is provided downstream of an air cleaner (not shown). 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 linked to an accelerator pedal 17 arranged in the driver's seat and is configured to rotate in a non-linear manner in order to limit 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 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 valves 18, 22. In the cylinder head 10A of the diesel engine 10,
An injection nozzle 34, a glow plug 36, and an ignition timing sensor 38 whose tip faces the engine combustion chamber 10B are provided. 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 waveform-shaped to form the same input interrupt terminal of the CPU 56A. Waveforms for taking direct shaping circuit 56
T, a waveform shaping circuit 56U for shaping the output of the engine speed sensor 46 into the other input interrupt terminal of the CPU 56A directly, 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 5 according to the calculation result of the CPU 56A.
It is composed of a drive circuit 56X for driving 2 and a common bus 56Y for connecting the above-mentioned respective constituent devices to transfer data and instructions. The operation of the embodiment will be described below. In this embodiment, the fuel injection amount, that is, the spill angle is determined by
It 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. . Then step 120
Then, as shown in the following equation, the spill angle ANGsp is set to the angle per tooth of the engine rotation sensor 46, for example, 1
The angle count term Csp of the spill angle is calculated by dividing by 1.25 ° CA. ANGsp / 11.25 → Csp + remainder (2) Next, the remainder of this calculation result is calculated using the engine rotation time T45 ₂ between 45 ° CA during the current spill predicted and calculated by the later-described engine rotation pulse input interrupt routine. , Spill angle time count term Tsp is converted into time, and this routine is exited. Remainder _{× T45 2/4 → Tsp ...} (3) On the other hand, the waveform shaping circuit 5 from the engine rotation sensor 46
The processing according to the engine rotation sensor output pulse input via 6U is executed according to the engine rotation pulse input interrupt (ICAP) routine as shown in FIG. That is, every time a pulse is input from the engine speed sensor 46, the process goes to step 210 to increment the engine speed interruption counter Cnirq. Next, in step 212, the count value of the counter Cnirq is the angle count term Csp of the spill angle obtained in step 120.
It is determined whether or not In short, the determination in step 212 is 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 time, the process proceeds to step 214, and the time count of the spill angle obtained in the preceding step 120 is calculated at the current interrupt time Tint as shown in the following equation. The spill is prepared by adding the term Tsp to the output comparison register OCR. After the end of step 214 or when the result of the determination in the above step 212 is negative, the process proceeds to step 216, and it is determined whether or not the tooth-missing position corresponds to the reference position. When the judgment result is positive and it is judged that it is the reference position,
Proceeding to step 218, the counter Cnirq is cleared. After the step 218 is completed, or if the result of the determination in the above step 216 is negative, the routine proceeds to step 220, where the count value of the counter Cnirq is the set value which is the calculation timing of the engine rotation time T45n between 45 ° CA, 1 (Corresponds to 0 °), 5 (corresponds to 45 °), 9 (corresponds to 90 °), 1
It is determined whether it is 3 (corresponding to 135 °). If the determination result is positive, the process proceeds to step 222, where the interrupt time Tlint 45 ° CA before 45 ° CA is subtracted from the current interrupt time Tint to obtain the current 45 ° CA engine rotation time T45n as shown in the following equation. calculate. Tint−Tlint → T45n (4) Next, in step 224, the current interrupt time Tint is changed to the interrupt time Tlin before 45 ° CA in preparation for the next calculation.
Move to t. Next, in step 226, determines the count value of the counter Cnirq is, 45 ° CA between the set value is a prediction timing of the engine rotation time T45 ₂ during spill, whether it is for example 1. If the judgment result is positive,
Proceeding to step 228, the i-th
Engine rotation time T between 45 ° CA during cylinder spill this time
Prediction calculation of 45 ₂ , i is performed. T45 ₂ , i = T45 ₁ , i × T45 ₂ , _i-1 / T45
₁ , _i-1 (5) Here, T45 ₁ , i is the engine rotation time between 45 ° CA immediately before the current spill of the i-th cylinder, T45 ₂ ,
_i-1 is 45 ° at the time of the previous spill of the immediately preceding cylinder (i-1)
Inter-CA engine rotation time, T45 ₁ , _i−1, is also the 45 ° CA-engine rotation time immediately before the previous spill of the immediately preceding (i−1) th cylinder. In this equation (5), the ratio between the value immediately before the previous spill and the value at the previous spill in the immediately preceding cylinder is
Considering that the cylinder is also maintained, the engine rotation time T45 ₂ between 45 ° CA during the current spill of the cylinder concerned,
Since i is predicted and matches the actual engine rotation fluctuation state, highly accurate prediction calculation can be performed. After the step 228 is finished, the routine proceeds to step 230, where it is judged whether or not the count value of the counter Cnirq is a set value, for example, 9 at which the electromagnetic spill valve 50 should be closed in preparation for the next opening control. If the determination result is positive, the process proceeds to step 232, and as shown in the following equation, the current interrupt time Tin
The sum of t and the margin time until completion of the interrupt calculation is added to the output comparison register OCR, and the electromagnetic spill valve 5
Prepare to close 0. Tint + α → OCR (6) After step 232, or after steps 220 and 22 described above
If the result of the determination at 6 and 230 is negative, this input interrupt routine is ended. Although not shown, the electromagnetic spill valve 50 is opened and closed at the time set in the output comparison register OCR. FIG. 7 shows an example of the relationship between the engine rotation sensor output and the engine rotation time between 45 ° CA calculated from this in this embodiment. In the present embodiment, the engine rotation time between the set crank angles at the time of the current spill of the cylinder is predicted by the equation (5) described above, and therefore highly accurate prediction according to the actual rotation fluctuation method. Calculation can be done. Note that the method of predicting the engine rotation time between the set crank angles at the time of this spill is not limited to this.

【The invention's effect】

As described above, according to the present invention, it is possible to improve the accuracy of the injection amount control without increasing the cost by using the rotary angular gear having the number of teeth that can be mass-produced as in the conventional case. Therefore, there is an excellent effect that smooth rotation with less engine vibration can be obtained even in a low rotation region where the rotation fluctuation is particularly large and engine vibration is large in the conventional method.

[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. FIG. 8 is a diagram showing an example of the relationship between the engine rotation sensor output and the engine rotation time between 45 ° CA in the above embodiment, and FIG. 8 is the engine rotation sensor output and 4 in the conventional example. ° is a diagram showing an example of the relationship between CA engine rotation time. 10 ... Diesel engine, 42 ... Injection pump, 42E ... Gear (rotation angle gear) 46 ... Engine rotation sensor, 50 ... Electromagnetic spill valve, 56 ... Electronic control unit (ECU), ANDsp ... Spill angle, Csp ... Angle count term, Tsp ... time count term, T45n, i ... 45 ° CA engine rotation time of the cylinder concerned, T45n, i−1 ... 45 ° CA engine rotation time of the immediately preceding cylinder.

Claims (2)

[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 of the electronically controlled diesel engine, the engine rotation time T between the set crank angles immediately before the previous spill is controlled.
_The procedure for calculating and storing _{n-1, i-1} and the engine rotation time T between the set crank angles immediately before the current spill
_Using the procedure for calculating _{n, i-1} and the value T _{n-1, i-1 of the} engine rotation time between the set crank angles immediately before the previous spill and the value T _{n, i-1} immediately before the current spill, A procedure for predicting and calculating the engine rotation time T _{n, i} between the set crank angles at the time, and a procedure for performing time conversion of the spill angle by using the predicted engine rotation time T _{n, i} between the set crank angles at the present spill time. An injection amount control method for an electronically controlled diesel engine, which comprises: 2. The engine rotation time T _{n, i} between the set crank angles during the current spill _, T _{n-1, i-1 of the} engine rotation time between the set crank angles before the previous spill value of the immediately preceding cylinder and immediately before the current spill. Engine rotation time T between set crank angles
_{n, i−1} , using the engine rotation time T _{n-1, i} between the set crank angles at the time of the previous spill of the cylinder, the following equation T _{n, i} = T _{n-1, i} × T _{n, i-1} / The injection amount control method for an electronically controlled diesel engine according to claim ₁ , wherein the predictive calculation is performed by T _{n-1, i-1} .