JPH0122946Y2 - - Google Patents

Description

[Detailed explanation of the idea]

The present invention relates to an electronically controlled fuel injection internal combustion engine. In electronically controlled fuel-injected internal combustion engines, ignition timing is controlled by controlling the engine speed to N and the intake air amount to Q.
In this case, a table map of ignition timing for N and Q/N is stored in memory, one combination of rotational speed N and intake air amount Q is actually measured while the engine is running, and the actual value is corresponded to the actual value. The ignition timing is calculated from a table, and an ignition device such as an igniter is operated so that ignition is performed at the calculated ignition timing. The ignition timing is determined by the combination of the rotational speed N and the fuel injection amount T _p , and the fuel injection amount T _p is linearly proportional to Q/N (T _p = K x Q/N).
Therefore, the ignition timing can be calculated using the table of N and Q/N as described above. By the way, the fuel injection amount T _p is determined by Q/N,
Conventionally, this value was calculated using software processing. That is, Q converts the analog signal from the air amount sensor into a digital signal, while N
is in the form of a digital signal from the crank angle sensor.
It was taken into the CPU, and the CPU calculated the Q/N. However, recently, an IC element has appeared which obtains a pulse signal representing the fuel injection amount T _p through hardware processing from an analog signal from an air amount sensor and a digital signal from a crank angle sensor. When performing ignition timing control with an electronic control system that employs such an IC element, conventionally, although the pulse signal representing the fuel injection amount T _p is obtained from the IC element, the representative value of the fuel injection amount T _p is A map was created based on Q/N. in this case,
This requires an unnecessary step of processing the signal from the air amount sensor in the CPU to calculate the ignition timing. Therefore, in the present invention, a map is created between N and T _p as a substitute for Q/N, and the ignition timing is calculated from N and T _p actually measured during engine operation. Therefore, the amount of intake air is used to calculate the ignition timing.
The originally unnecessary step of incorporating it into the CPU is omitted. An embodiment of the present invention will be described below with reference to the drawings. In FIG. The fuel is introduced into the combustion chamber 20 together with the fuel from the fuel injection valve 18 through the fuel injection valve 18 . An ignition plug 22 is provided in the combustion chamber 20 and connected to an ignition coil 26 via a distributor 24 to connect the igniter 2
8 generates a high voltage current in the ignition coil at a predetermined crank angle, and ignition is performed by the ignition plug 22. Exhaust gas is taken out from the combustion chamber 20 to an exhaust manifold 30 and guided to a catalytic converter 36 via an exhaust pipe 34. The control circuit 40 controls the operation of the fuel injection valve 18 and the igniter 28, and receives signals from various sensors. That is, the air amount sensor 12 outputs an analog signal indicating the intake air amount Q, and the crank angle sensor 44 provided in the distributor 24 outputs an analog signal indicating the rotational speed of the distributor shaft, in other words, the rotational speed N of the engine. A signal is input. From the crank angle sensor 44, as shown in FIG.
A pulse signal that goes high every 180°CA is obtained.
Assuming the engine is a 4 cylinder cylinder, the top dead center (TDC)
occurs every 180° CA, and is constructed so that it rises just before the top dead center and falls at the top dead center. Note that although signals from other sensors are also input, these are omitted because they are not directly related to the present invention. In FIG. 3, which shows the configuration of the control circuit 40 in a block diagram, 50 is an analog IC element for generating fuel injection pulses, which receives the crank angle pulse from the waveform shaping circuit 51 and the analog signal from the intake air amount sensor 12. This IC element 50 is conceptually constructed as shown in FIG. That is, a pulse signal every 180° CA (TDC) from the crank angle sensor 44 (FIG. 2 b) is converted into a pulse signal every 360° CA (Fig. It enters the Q/N calculation circuit 503 as (c) in Figure 2.
The Q/N calculation circuit 503 calculates the Q/N from an analog signal indicating the intake air amount Q from the air amount sensor 12 and a crank angle signal representing the engine rotation speed N.
A pulse signal corresponding to is applied to one input of AND gate 504. The output from the monostable 501 is input to the other input of the AND gate 504, and as a result, the AND gate 504 receives the Q/N signal when the pulse width is smaller than the pulse width from the monostable. The output is output as is, and when the monostable pulse width is exceeded, the output is the same as the monostable pulse width. That is, the pulse width t _p of the T _p signal
The maximum t _pnax of is set by 501. The output of the AND gate 504 is connected to one input of an OR gate 505, and the other input of the OR gate 505 is connected to a second monostable 502, which is connected to a divide-by-half circuit 502.
Receives signal from 06. The OR gate 505 outputs a signal with a pulse width t _p corresponding to Q/N every 360° CA (FIG. 2, E). The monostable 506 guarantees the pulse width of the Q/N signal even if the pulse width t _p falls below a predetermined value, and the minimum pulse width t _pnio
Set. Returning again to FIG. 3, the T _p pulse shaping analog IC 50 is connected to the CPU 59 and the T _p signal is applied to its interrupt port. CPU5
9 has another interrupt port to which the crank angle signal from the waveform shaping circuit 51 is applied. Input interface circuit 52 receives signals from each digital sensor, and A/D converter 54 receives signals from each analog sensor. The output interface circuit 56 is connected to the igniter 28 and the injection valve 18. The CPU 59 is connected to these interfaces 52 and 56 and the A/D converter 54 via a bus 58, and is further connected to the ROM 60 and RAM 62. The configuration for realizing the ignition timing control according to the present invention is stored in the ROM 60 in the form of software. Before explaining this software, please refer to the second
The time chart shown in the figure clarifies the ignition timing control principle of the present invention and facilitates understanding of the software. In Figure 2, A indicates the crank angle, and 4
In a cylinder engine, top dead center (TDC) occurs every 180 degrees. FIG. 4B shows a crank angle signal from the crank angle sensor 44, which is configured to be at a high level for a predetermined period from before TDC to TDC every 180 degrees of crank angle. analog
The IC 50 generates a fuel injection pulse T _p every 360 degrees TDC as shown in E, and the pulse width t _p represents the fuel injection time as described above. Based on the pulse width t _p of this fuel injection pulse T _p , the CPU 59 calculates a map of the crank angle θ before the next TDC, and outputs an ignition output as shown in F so that ignition occurs at that crank angle. Incidentally, the injection pulse T _p is of course also used to drive the fuel injection valve 18, but since this is not directly related to the present invention, the following explanation will be omitted. The software configuration for realizing the time chart as shown in FIG. 2 will be explained below with reference to the flowcharts shown in FIG. 5 and subsequent figures. This software is of course stored in the ROM 60 in the form of a program. FIG. 5 shows a part of the main routine for calculating the ignition timing. At 100, it is determined whether the ignition timing calculation request flag f is 1 or 0. This flag f is set when ignition processing is performed as described later. If f=0, it is determined that calculation of ignition timing is unnecessary, branches to _N0 , and exits from this routine. f=
In the case of 1, the flag f is cleared at 102, the data of the engine rotation speed N stored in the RAM 62 is fetched at 104, and the pulse width t _p of the fuel injection pulse T _p stored in the RAM 62 is fetched at 106. Ingest data. At step 108, the ignition timing θ is calculated by map search from the actually measured N and pulse width _tp . That is, the ROM 60 stores the following table of ignition timing for many combinations of engine speed N and pulse width _tp .

[Table] The CPU 59 calculates the ignition timing θ by interpolation from the actually measured N and t _p taken in steps 104 and 106, respectively. FIG. 6 shows an interrupt routine that is started by the rising and falling edges of the crank angle signal. When this interrupt request enters the interrupt port of CPU59,
At 114, it is determined whether or not it is a falling edge. If it is determined that it is falling (time t ₁ in FIG. 2D), the process goes to 116 and calculates the time t ₂ at which energization to the igniter starts (that is, the rise of the ignition pulse). This calculation is t ₁
is overwritten by the free-run timer, and
The time T180 between TDC can be calculated, and θ is the fifth
It is calculated by the main routine explained in the figure,
In addition, since the duration time T _ON of the ignition pulse is known, it can be calculated. In the next step 118, the energization register is set to _t2 . When the time _t2 set in the register has elapsed, the CPU 59 starts time interrupt processing and outputs an ignition signal to the igniter 28 via the output interface 56. 120 indicates the setting of the ignition timing calculation request flag f, which is used in the above-mentioned main routine. If it is determined in step 114 that there is a rise, the process proceeds to step 122 in order to calculate the end time _t3 of the ignition output.
This can also be easily calculated since θ is known. In the next 124 registers this calculated t ₃
Set to . When this t ₃ is reached, the interrupt causes
The CPU 59 turns off the power to the igniter 28, and ignition is performed at the crank angle θ. 7 and 8 show routines for storing t _p in the RAM, of which FIG. 7 is an interrupt routine that starts at the rising edge of the crank angle signal. At 130, the current time _t1 is stored in box A of the RAM 62. FIG. 8 shows an interrupt routine that starts at the falling edge of the T _p pulse. At 132, the time t ₁ ' at that time is stored in the box B of the RAM 62, and at 134, the difference between B and A, that is, the pulse width t _p is stored in the RAM 62, and is used in the main routine to calculate θ, as described above.

[Brief explanation of the drawing]

Fig. 1 is the overall configuration of the internal combustion engine of the present invention, Fig. 2 is a time chart, Fig. 3 is a block diagram of the control circuit, Fig. 4 is a block diagram of the analog IC for _tp pulse shaping, Figs. Figures 6, 7, and 8 are flowcharts. 12... Air amount sensor, 16... Throttle valve, 18... Fuel injection valve, 20... Combustion chamber, 22
... Spark plug, 24 ... Distributor, 26
...Ignition coil, 28...Igniter, 40...
Control circuit, 44... Crank angle sensor, 50...
Analog IC for _Tp pulse shaping.

Claims (1)

[Scope of Claim for Utility Model Registration] Memory means for storing representative values of ignition timing for multiple combinations of engine speed and fuel injection amount in a fuel-injected internal combustion engine equipped with an electronically controlled ignition device; A first sensor that detects the amount of air during operation and generates an analog signal according to the amount of intake air; a second sensor that generates a pulse signal according to the rotational speed of the engine during operation; an electronic circuit that outputs a pulse signal having a pulse width according to the fuel injection amount from an analog signal indicating the intake air amount and a pulse signal indicating the rotation speed from the second sensor; pulse width detection means for detecting the fuel injection amount from the pulse width; and memory means for calculating the ignition timing corresponding to one combination of the rotation speed from the second sensor and the fuel injection amount from the pulse width detection means. An ignition timing control device for a fuel injection internal combustion engine, comprising an ignition timing calculation means and a drive means for outputting an activation signal to an ignition device so that the engine operates at the calculated ignition timing.