JPS61277849A - Electronic controller for internal-combustion engine - Google Patents

Abstract

PURPOSE:To enable parallel operation of fuel supply and ignition timing by applying start trigger onto engine rotation detecting means of first CPU with predetermined timing of crank angle signal to be fed to second CPU. CONSTITUTION:First CPU 1 for operating fuel injection has means for detecting at least one engine parameter or engine rotation. On the basis of crank angle signal T24 to be fed from crank angle sensor 16 immediately after provision of TDC signal from TDC sensor 15, second CPU 2 for operating the ignition timing will detect the first stage (0) and following stages in crank angle positions defined into six between TDC positions. Upon detection of stage 3, trigger signal is received from CPU 2 through operation starting trigger signal line 26 to execute operating program of CPU 1.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) This invention relates to an electronic control device for an internal combustion engine, and in particular,
This invention relates to an electronic control device equipped with a central processing unit that separately controls fuel supply and ignition.

(Technical background of the invention and its problems) As a conventional electronic control device for controlling the fuel injection amount and ignition timing of an internal combustion engine, for example, Japanese Patent Laid-Open No. 53-762
There are some such as those disclosed in No. 31. This control device consists of one central processing unit (hereinafter referred to as rCPUJ).
), in addition to an engine water temperature signal, an intake pipe absolute pressure signal, and a rotational position signal of the engine crankshaft, i.e. 1, a crank angle signal generated every time the crankshaft rotates by a predetermined angle in relation to the rotation of the crankshaft, 1. Engine operating parameters such as a reference position signal generated twice every rotation are introduced, and based on these input signals, the common CPU executes quantity calculations related to fuel injection amount and ignition timing control.

Incidentally, in recent years, in order to meet the demands for improved driving performance, the content of the calculation program for each controlled object has become more complex, and the amount of processing executed by the CPU has increased.

However, in conventional electronic control devices, multiple control objects are processed by a common CPU, which makes it impossible to cope with the increase in the amount of calculation processing for each control object as described above. At high engine speeds, when the time available for calculation processing is shorter than at low engine speeds, it is not possible to meet the demand for more accurate engine control. CPU with the highest computational processing power (for example,
Although it is possible to meet the above requirements by using a 32-bit, 64-bit, etc. If the engine operating parameters required for each engine are taken in by separate sensors, input circuits, etc., multiple CPUs each containing input circuits etc. will be required, making the device complicated and huge.
Difficulties are posed in maintenance.

(Object of the Invention) The present invention has been made in view of the above points, and its purpose is to control multiple control targets such as fuel injection amount and ignition timing without complicating the device. An object of the present invention is to provide an electronic control device for an internal combustion engine that enables more accurate and complicated control.

(Structure of the Invention) In order to achieve the above object, according to the present invention, an internal combustion engine electronically controls an internal combustion engine that electronically controls a fuel injection amount and ignition timing according to operating state parameters of the internal combustion engine. The control device includes a first central processing unit that calculates the fuel injection amount and a second central processing unit that calculates the ignition timing, and the second central processing unit includes: A crank angle position signal representing at least a predetermined crank angle position is input, and the first central processing unit has engine rotation speed detection means for detecting an engine rotation speed, which is one of the engine parameters; There is provided an electronic control device for an internal combustion engine, wherein the central processing unit No. 2 applies a start trigger to the engine rotation speed detecting means at a predetermined timing of the input crank angle signal.

(Embodiments of the invention) Examples of the invention will be described below based on the drawings. 1st
The figure is a diagram showing the overall configuration of an electronic control device according to the present invention. An electronic control unit (ECU) includes a first CPU 1 that controls fuel supply to the internal combustion engine, and a second CPU that controls ignition timing of the air-fuel mixture formed by the supplied fuel.
U2 is provided. The first CPU 1 has a read-only memory that stores various calculation programs executed by the first CPU 1 and various tables used to calculate the fuel injection amount, in other words, the opening time of the fuel injection valve 8. (hereinafter referred to as FROMJ) Random access memory (hereinafter referred to as rRA) that temporarily stores 3° calculation results, etc.
MJ) 4 is provided. The input side of the first CPUI is connected to a P that detects the value of the internal pressure in the intake pipe (not shown) of the internal combustion engine, converts it into a digital value, and outputs it.
The e-transducer 5 is connected to another transducer 6 that detects operating parameter values such as intake air temperature, engine cooling water temperature, throttle valve opening, and 0□ concentration in exhaust gas, converts them into digital values, and outputs them. It's faded. Further, a counter circuit 7 that counts the opening time of the fuel injection valve based on fuel injection time data to be described later is connected to the output side of the first CPUI, and the output line of this counter circuit 7 is connected to the fuel injection valve 8. It is connected to the. Further, drive signal lines for the EGR valve, solenoid valve for idle control, etc. are connected to actuators 9 for these valves. Note that the fuel injection valve 8 is arranged for each cylinder of the internal combustion engine, and accordingly, the counter circuit 7 is also provided with the same number of counters as the number of cylinders.

On the other hand, the second CPU 2 includes a ROM II and a RAM that have the same functions as in the first cPUl.
12 are provided. A waveform shaping circuit 13 is connected to the input side of the second CPU, and this waveform shaping circuit M13 (7)
A cylinder discrimination (CYL) sensor 14 that outputs a one-pulse signal T01 for cylinder discrimination at a predetermined crank angle position of a specific cylinder of the engine on the input side;
A reference crank angle signal T is generated at a predetermined crank angle position of BTDC (before top dead center) of each cylinder every 80° rotation. A top dead center (TDC) sensor outputting 4 15. and a crank angle sensor 16 which outputs a signal T24 of one pulse every time the crankshaft rotates by 30 degrees. Further, on the output side of the second CPU 2, a turn-on counter 17 and a turn-off counter 18 are connected in parallel.
An ignition circuit 21 and a distributor 22 are sequentially connected to the flip-flop circuit 19 through the ignition circuit 21 and a distributor 22, and spark plugs 23a to 23d arranged for each cylinder are connected to the distributor 22. The ignition circuit 21 is provided with a well-known ignition coil (not shown) consisting of a primary coil and a secondary coil for generating high voltage. Further, the turn-on counter 17 and the turn-off counter 18 both use down counters, and as will be described later, energization start timing data calculated by the second CPU 2 is set in the turn-on counter 17, and the energization start time data, which will be described later, is set in the turn-on counter 17. In the crank angle position range to be started (hereinafter simply referred to as "energization stage"), the clock pulse is subtracted from the stage starting point to define the timing of energization to the primary coil of one ignition circuit 21. On the other hand, the turn-off force counter 18 is set with the ignition timing data calculated by the second CPU 2 in the same manner as described above, and the 29 is subtracted and counted by clock pulses from the stage start point at a predetermined ignition stage to be described later. It determines when to cut off the current to the secondary coil and generates high voltage for ignition on the secondary coil side.

Further, the following signal lines are connected between the first CPU I and the second CPU 2.

First, the cylinder discrimination (CYL) signal T. A signal line 25 marked □ is connected between the output side of the waveform shaping circuit 13 and the input side of the first CPUI. In addition, a signal line 2G that provides a trigger signal for starting calculations to the first CPU 2 is connected from the second CPU 2 to the first CPU 2, and communication lines 27 and 28 for data transfer are connected between the CPU 2 and the CPU 2. It is connected. The communication line 28 is for transferring data such as engine parameters and transmission command signals from the first CPU 2 to the second CPU 2, and the communication line 27 is for transferring data such as engine parameters and transmission command signals from the second CPU 2 to the first CPU 2. This is for sending a confirmation signal, etc. in response to the above-mentioned transmission command. Each CPU
I, 2 are provided with a parallel-to-serial conversion circuit and a serial-to-parallel conversion circuit at the transmitting end and receiving end of each communication line 27 and 28, respectively, in order to serially and asynchronously transfer data as described later. is installed. Code 29 is Me
This Me counter 29 has a second CPU
A lead-out line 3o for a start trigger signal is connected from the CPU 2, and its output side is connected to the first CPUI. Me counter 29c No. 277) CPU2 is BTDC90, for example.
The count value is stored in a register (not shown) by a start trigger signal generated when the crank angle position of `` is detected, the count value is reset to zero, and counting of clock pulses of a constant frequency is started again. Therefore,
The count value stored in the register of the Me counter 29 represents the number of clock pulses between the current and previous occurrences of the start trigger signal, ie, the time interval between occurrences of the start trigger signal.

This count value is read by the first CPUI and used to calculate a parameter Me that is proportional to the reciprocal of the engine speed Ne, and this parameter Me is one of the parameters when calculating the fuel injection amount as information representing the engine speed. used as one.

Next, as shown in FIG. 2, the parallel-serial conversion circuits and the series-
The parallel conversion circuit on the communication line 28 side will be explained.

Reference numeral 31 is a parallel-to-serial conversion circuit that adds 8-bit command or operating parameter value data, a command or data discrimination bit, and start and stop bits.
A latch circuit 32 latches 1 bit as 1 frame (Fig. 7), and 11-bit data input in parallel from this latch circuit 32 is input via a signal line 34, 1 bit for each clock pulse input. It is composed of a shift register 33 for serial transfer. The output terminal of the shift register 33 is the output port 351 communication line 28
and is connected to the input end of the shift register 39 on the second CPUZ side via the input port 36. This shift register 39 and latch circuit 38 constitute a serial-to-parallel conversion circuit 37, and the transferred 11-bit data is stored in the shift register 38 by the reverse procedure of the parallel-to-serial conversion circuit 31. Note that reference numeral 40 is an input line for clock pulses input to the shift register 39.

The clock pulses input from this input line 4o and the clock pulses input from the signal line 34 on the transmitting side are asynchronous but have the same pulse period. shift register 3
9, a signal corresponding to a stop bit of data, which will be described later, is supplied to the clock input terminal of the latch circuit 38 via an output line 41. is used as a signal to notify that the data transfer for the first frame has been completed, as in the case of transferring the data for the first frame.

Next, the operation will be explained with reference to FIGS. 3 to 7.

First, ignition timing control by the second CPU 2 will be described.

The second CPU 2 receives CYL from each sensor 14 to 16.
Signal T0, TDC signal T, and crank angle signal T
24 is waveform-shaped by the waveform shaping circuit 13 and inputted (FIGS. 3(,) to (C)). Among these, CYL signal T. □ is also input to the first CPUI via the signal line 25 as a signal for determining the order of fuel injection to each cylinder. Note that the stage in FIGS. 3 and 4 uses a crank angle signal T24 to measure the crank angle between two adjacent top dead centers (TDCs).
The crank angle from each rise of T24 to the next rise of the crank angle signal T24 is divided into six regions at one interval, and each region is called a stage and numbered from 0 to 5. The second CPU 2 executes a crank interrupt processing program (FIG. 4(b)) which is executed every time the crank angle signal T24 is generated as an ignition timing control program, and an end of the crank interrupt processing program which is executed in the third stage. Two processing programs, the θIG-DUTY calculation processing program (Fig. 4 (C)), which is performed subsequently to Prioritize execution.

First, in the crank interrupt process, the energization stage (in the example of FIG. 4, stage 2
), a predetermined stage at which the turn-off counter 18 should be started (stage 4 in the example of FIG. 4), a predetermined stage at which the first CPU (to be described later) should execute FI calculation processing (stage 3 in the example of FIG. 4), etc. A stage determination is made. In particular, the second CPU 2 performs the third stage determination. In particular, when the second CPU 2 detects the third stage, it sends the first CPU via the calculation start trigger signal [26].
Provides a trigger signal to the PUI.

As a result, a trigger signal is supplied to the FI in the first CPUI. This allows FI in the first CPUI to
Computation processing begins. The second CPU 2 further performs control such as detection of the generation time interval ME, i of the crank angle signal T24 and activation of the turn-on counter 17 and the turn-off counter 18 in crank interrupt processing.

On the other hand, in the θIG-DUTY calculation process, the advance angle control value θI
G, energization control value DUTY (coil energization time ratio % to TDC signal generation time interval);

Calculation of each data of energization timing TDUT and ignition timing TIG is executed.

The arithmetic processing of each of the above data will be explained in more detail.

The advance angle control value θIG is calculated according to the following equation (1) from various factors such as the engine rotational speed Ne, the intake pipe absolute pressure PBA, and the engine coolant temperature Tw.

θIG=θMAP+θIGCR...(1) Here, θ
MAp indicates the basic advance angle value, which is read from the map stored in ROMII based on the engine speed Ne and intake pipe absolute pressure PEA, and θIGCR is a correction variable value for the basic advance angle value, and is the engine cooling water temperature Tw. , read out from the table stored in the ROM II according to the intake air temperature TA, atmospheric pressure PA, etc.

The engine speed Ne used for calculating the oMAp value is given from the Me counter 24 built in the second CPU 2, and the value Me is determined by the crank angle shown in FIG. 3(c) and FIG. 4(a). Each interval of each stage O to 5 of the signal T24 is determined by a clock pulse of a constant period (fixed clock pulse).
Additional fee Me (
=Mes, +ME, 1+MEa*+MEaa+ME@4
+MEsi).

Further, the energization control value DUTY is a function of the engine rotation speed Ne, and is read out from the table stored in the ROMII as described above, and is given by correcting this read value with the battery voltage. 'The ignition here is BTDCO~
This is performed within a range of 60°, in other words, it is performed on either stage 4 or 5. Specifically, the turn-off counter 18 starts counting the data input to the turn-off counter 18 from the rise of the stage 4, and when the count reaches 0, the power to the secondary coil is cut off. The input value to this turn-off counter 18 is
Then, the TIG is a one-time angle conversion value, and its value is obtained from the advance angle control value θIG and the Me value obtained as described above.

Similarly, the energization start time TDUT is also the advance angle control value θ1G.
, is a value obtained by converting the angle determined by the energization control value DUTY and the Me value, and thereby any position between the stages can be set.

Then, when the stage start point at which the ignition coil should start being energized is detected, the turn-on counter 17 starts counting, and when the count value reaches O after counting down the value corresponding to the TDUT value, that is, the set energization starts. When the timing is reached, the flip-flop circuit 19 is set, and the primary coil of the ignition circuit 21 starts to be energized. As described above, the flip-flop circuit 19 is reset from the start of stage 4 to the ignition timing TIG.

The flip-flop circuit 19 is reset to the ignition circuit 2.
Outputs the energization off signal to 1, and outputs the energization off signal to 2 at the timing of energization off.
Next, a high voltage for ignition is generated in the coil, and the plug 22 is ignited at the specified advance angle position.

On the other hand, the first CPU 1 executes the FI calculation processing program. This FI calculation processing is performed by the trigger signal q which is output from the CPU 2 to the CPUI via the signal line 26 when the crank angle position of the stage 3, that is, the BTDC 90' is detected in the crank interrupt processing on the second CPU 2 side.
Execution begins upon receiving the input. Further, the timing at which the trigger signal q is activated is changed depending on the engine operating state, such as engine speed Ne, intake pipe absolute pressure PBA, etc., and the injection timing is thereby controlled. In this FI calculation process, the intake pipe absolute pressure signal PB^ from the PBA transducer 5, the throttle valve opening signal θTH1, the O in the exhaust gas,
, 'a degree detection value, etc., reading of Me data counted by the Me counter 29, calculation of the fuel injection time T0LIT, which will be described later, and counter of a predetermined cylinder in the counter circuit 7 at the end of the calculation. Executes startup control, etc.

The above-mentioned fuel injection time T o UT is calculated by the following equation.

TogT=Ti　XK1+K.

Here, Ti indicates the basic fuel injection time of the fuel injection valve 8, and this basic fuel injection time Ti is, for example, the absolute pressure P in the intake pipe.
It is read out from the ROM 3 based on BA and the engine speed Ne. K and 2 are supplementary coefficients and correction variables respectively calculated according to the engine parameter signals from the various sensors mentioned above, and depending on the engine operating state,
Starting characteristics.

Calculations are performed based on predetermined calculation formulas so that various characteristics such as exhaust gas characteristics, fuel efficiency characteristics, and engine acceleration characteristics are optimized. The first CPUI is the fuel injection time T as described above.
At the same time as the calculation of the fuel injection time Tou is completed, the data of the fuel injection time Tou is set in the counter of a predetermined cylinder in the counter circuit 7, and the counter is activated. The counter subtracts this data and supplies a valve opening time signal having a value corresponding to the fuel injection time data as a drive signal to the fuel injection valve 8 to control the fuel supply amount.

Next, data transfer such as engine operating parameter values via the data transfer signal lines 27 and 28 will be described. This data transfer is executed by a serial asynchronous method, and the above-mentioned crank interrupt processing executed by the second CPU 2, θ
The IG-DUTY calculation process and the FI calculation process executed by the first CPUI are executed when they are not being executed (this is referred to as "background"). First, when the first CPU is in the background where the FI calculation process is not being performed, the first CPU 2 sends a transmission command 5END to the second CPU 2 via the communication line 28, as shown in FIG.
Send to. In response, if the second CPU 2 is not in the processing execution state such as crank interrupt processing but in the data reception enabled state, it responds to the first CPU via the communication line 27 with an acknowledgment signal ACK indicating the data reception enabled state. do. After the response, the first CPU 1 uses a clock pulse to shift the shift register 3.
Drive 3. This drive causes the shift register 33 to shift.

Every time a clock pulse is input, the data DATA containing the engine operating parameter values input in parallel through the latch circuit 32 is output one bit at a time while being shifted. 2 to CPU 2. The shift register 39 in the second CPU 2 serially latches the transferred data DATA one bit at a time using a clock pulse input from the signal line 40.

The latch circuit 38 is driven at the input timing of the last stop bit following this data DATA, and the data DATA is transferred from the shift register 39 to the latch circuit 38.
Bits are latched at the same time.

The data DATA latched by the latch circuit 38 is
It is written into the RAM 12 by the writing process of the CPU 2. Note that the second CPU 2 is also provided with a request instruction for requesting the first CPU 1 to transfer data. Therefore, the RAM 12 in the second CPU 2 has the first
When transferring 62 bytes of data, in which the latest values of each engine operating parameter are always written, like the RAM 4 on the CPU side of the
CPU 2 first reads 1 byte of data DATA 1.
After receiving , it sends an acknowledgment signal ACK to the first CPUI, and then receives the subsequent 1 byte of data DATA 2.

Note that when interrupt processing occurs in the CPU during such data transfer, the clock pulses to the shift registers 33 and 39 become non-input, the data transfer is interrupted, and priority is given to the interrupt processing. After this interrupt processing ends, data transfer is resumed.

Note that the fuel supply control in this invention may be any control such as fuel injection amount or injection timing, and the ignition control may be any control such as ignition timing or energization time.

(Effects of the Invention) As detailed above, according to the electronic control device for an internal combustion engine of the present invention, the first central processing unit calculates the fuel injection amount and the second central processing unit calculates the ignition timing. a processing unit, the second central processing unit receives at least a crank angle position signal representing a predetermined crank angle position; The second central processing unit has an engine rotation speed detection means for detecting the rotation speed, and the second central processing unit applies a start trigger to the engine rotation speed detection means at a predetermined timing of the input crank angle signal. , it is possible to perform calculations on the fuel supply amount and ignition timing control objects in parallel, increasing the amount of calculation processing for each control object among these multiple control objects, and further reducing the time available for calculation processing. Expensive CPU with high processing power even for high speed control
The effect is that accurate and complex control can be achieved without using the . In addition, the input stage processing circuit such as the waveform shaping circuit for the crank angle position signal is operated by the second CPU.
Since it is possible to share the same equipment, it is not necessary to use an expensive CPU, and together with this, it is possible to reduce the product cost.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the overall configuration of an electronic control device for an internal combustion engine that implements the method of the present invention, and FIG. 2 shows latch circuits, shift registers, etc. that perform data transfer between the first and second central processing units. 3 is a block diagram of a data transfer circuit consisting of; FIG. 3 is a timing chart showing the pulse generation timing of the TDC signal, crank angle signal, etc.;
Fig. 4 is a timing chart showing when to start energizing the ignition coil, when to stop energizing, etc. Figs. 5 and 6 are timing charts showing the timing of transferring data such as engine operating parameter values, and Fig. 7 is a timing chart showing when to transfer data such as engine operating parameter values. FIG. 2 is a block diagram showing the structure of one frame of data. 1... first central processing unit (CPU), 2...
Second central processing unit (CPU), 5... Intake pipe absolute pressure transducer, 8... Fuel injection valve. 16...Crank angle sensor, 23a-23d...
Spark plug, 26...Trigger signal line for starting calculation, 27.2
8... Communication line for data transfer, 31... Parallel-serial conversion circuit, 37... Series-parallel conversion circuit.

Claims (1)

[Claims] 1. In an electronic control device for an internal combustion engine that electronically controls a fuel injection amount and ignition timing according to operating state parameters of the internal combustion engine, a first center that calculates the fuel injection amount; and a second central processing unit that calculates ignition timing, the second central processing unit receives at least a crank angle position signal representing a predetermined crank angle position; The first central processing unit has engine rotation speed detection means for detecting the engine rotation speed, which is one of the engine parameters, and the second central processing unit has a predetermined value of the input crank angle signal. An electronic control device for an internal combustion engine, characterized in that a start trigger is applied to the engine rotation speed detection means at a timing.