JPH0442544B2 - - Google Patents

Description

TECHNICAL FIELD The present invention relates to an ignition timing control device for an internal combustion engine.

(Technical background of the invention and its problems) Ignition timing control during normal operation of an internal combustion engine uses a so-called TDC signal indicating a predetermined crank angle position of the engine crankshaft, a crank angle signal indicating a predetermined rotation angle of the crankshaft, and an intake air Calculates and sets the optimal ignition timing for the engine operating condition using various signals such as the internal pipe absolute pressure signal, engine temperature signal, and even intake air temperature signal as engine operating parameters,
Based on the set ignition timing, the energization of the ignition coil is controlled (hereinafter referred to as calculation ignition control).

However, when the detection of various engine operating parameters necessary for calculating the above-mentioned ignition timing has not been completed, such as when starting the engine, calculation ignition control cannot be performed.

Furthermore, at low temperatures, the viscosity of the engine oil and the sliding resistance of various parts of the engine increase, which may cause the engine speed to become unstable and cause rotational fluctuations during cranking or even during idling. In other words, the intervals at which the TDC signal and crank angle signal are generated are not constant and become unstable. If calculation ignition control is performed in such a case, it will not be possible to calculate and set appropriate ignition timing, which will make engine operation unstable and impede drivability.

Therefore, since the TDC signal is a pulse signal generated at a predetermined crank angle position before top dead center (TDC) at the end of the compression stroke of each cylinder, this TDC signal is used to determine when to start energizing the ignition coil and when to stop energizing the ignition coil. In other words, ignition timing control that enables so-called fixed ignition control to control the ignition timing, and switches the ignition control to either the fixed ignition control or the calculated ignition control at a predetermined value of the engine rotation speed. Devices have been proposed (eg US Pat. No. 3,756,212).

However, when switching between computational ignition control and fixed ignition control based only on the engine speed, there are the following problems.

That is, since the ignition energy stored in the ignition coil depends on the battery voltage, the calculation ignition control makes a correction to lengthen the energization time of the ignition coil when the battery voltage is low to prevent misfires and the like from occurring. However, when the engine is started, the battery voltage may drop suddenly due to the operation of the starter, for example, so if fixed ignition control is switched to calculated ignition control in such a case, it is difficult to perform the optimal control as described above, resulting in a misfire. etc. will occur, impeding drivability.

(Object of the Invention) The present invention has been made in order to solve such conventional problems, and an object of the present invention is to provide an ignition timing control device for an internal combustion engine that can optimize the switching timing of ignition control. purpose.

(Structure of the Invention) In order to achieve the above object, according to the present invention,
a first ignition control means for controlling energization of an ignition coil based on ignition timing set to an optimum value for engine operating conditions in accordance with operating parameters of the internal combustion engine; a crank angle position detection means for generating a crank angle signal based on the crank angle signal; a second ignition control means for controlling energization of the ignition coil depending only on the crank angle signal; and the first and second ignition control means. In an ignition timing control device for an internal combustion engine, the ignition timing control device for an internal combustion engine is provided with a switching control means for controlling switching of one of the ignition coils, wherein the switching control means controls a plurality of ignition timings including at least an engine rotation speed and a power supply voltage of a power source that supplies power to the ignition coil. It has a determining means for determining which of the first and second ignition control means should be switched in accordance with an operating parameter, and the determining means switches the ignition control means from the second ignition control means to the first ignition control means. When it is determined that the control should be switched to the first ignition control means, the control is switched to the first ignition control means after a predetermined number of crank angle signals corresponding to a period sufficient to at least calculate a stable engine rotational speed are generated from the time of the determination. There is provided an ignition timing control device for an internal combustion engine, characterized in that the setting of the ignition timing is completed during a period in which the predetermined number of crank angle signals are generated by the first ignition control means.

(Description of Embodiments) Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing the overall configuration of an ignition timing control device according to the present invention.

This ignition timing control device performs ignition control of, for example, a four-cylinder internal combustion engine (not shown), and is mainly configured with a central processing unit (hereinafter referred to as CPU) 10, and an input circuit 1 is connected to the input side of the CPU 10.
Various parameter sensors are connected via 1. More specifically, an absolute pressure P _BA sensor 12 that detects the absolute pressure P _BA in the intake pipe (both not shown) downstream of the throttle valve of the engine is inserted into the circumferential wall of the cylinder filled with cooling water in the engine body. , cooling water temperature
an engine water temperature (Tw) sensor 13 that detects Tw;
Battery voltage (V _B ) to detect battery voltage V _B
Sensor 14 and throttle valve opening (θ _TH ) sensor 1 that detects the valve opening θ _TH of the throttle valve in the intake pipe.
5 is connected to the CPU 10 via the level correction circuit 11a of the input circuit 11 and the A/D converter 11b. The A/D converter 11b converts each analog signal into a digital signal from the above-mentioned absolute pressure sensor 12, engine water temperature sensor 13, battery voltage sensor 14, and throttle valve opening sensor 15, which have been corrected to a predetermined voltage level by the level correction circuit 11a. Then, the digital signal is supplied to the CPU 10.

It is also installed around the engine's camshaft, for example, and measures the top dead center (TDC) at the end of each cylinder's compression stroke.
a first predetermined crank angular position (e.g.
A _T04 sensor 17 that generates a _T04 signal pulse that falls at a second predetermined crank angle position (for example, 10°BTDC) is connected to the CPU 10 via a waveform shaping circuit 11d of the input circuit 11. has been done. The waveform shaping circuit 11d is the T ₀₄ sensor 17
The T ₀₄ signal pulse from is shaped into a rectangular pulse (pulses Sa ₄ and Sa ₂ in FIG. 2a) and supplied to the CPU 10. Here, the pulse width T of the T ₀₄ signal represents the time interval between the detection time of the first predetermined crank angle position and the detection time of the second predetermined crank angle position.

Similarly to the T ₀₄ sensor 17, the T ₂₄ sensor 16 is attached around the camshaft, and during one rotation of the camshaft, that is, during two rotations of the crankshaft (not shown), 24 sensors are placed at equal intervals (crankshaft generate pulses (at 30° intervals). _T24 sensor 16 is waveform shaping circuit 1
_T24 signal pulse (second
The pulses S ₃₅ , S ₄₀ ~ ₄₅ , S ₂₀ , etc. shown in figure b are the CPU
10.

On the other hand, an ignition circuit 20 is provided on the output side of the CPU 10, and a switching circuit 2 is provided on the output side of the ignition circuit 20.
1 to the primary coil 22a of the ignition coil 22.
is connected. Secondary coil 2 of ignition coil 22
2b is a spark plug 25a of each cylinder via a power distributor 24.
~25d. The ignition circuit 20
The primary coil 22a of the ignition coil 22 is connected to the ignition coil 22 via the switching circuit 21 in response to the energization control signal from the CPU 10.
A predetermined coil energizing power is supplied to the coil.

Furthermore, the waveform shaping circuit 11d and the switching circuit 2
A fixed ignition circuit 29 is inserted between 1 and 2, and this fixed ignition circuit 29 is connected to the primary coil 22a of the ignition coil 22 via the switching circuit 21 for a predetermined energization time defined by the pulse width T of the _T04 signal. energizes the coil.

The switching circuit 21 receives the switching signal a from the CPU 10 and switches and connects the primary coil 22a of the ignition coil 22 to either the ignition circuit 20 or the fixed ignition circuit 29.

Incidentally, a ROM 27 for storing calculation programs and the like and a RAM 28 for temporarily storing calculation results and the like are connected to the CPU 10 via a bus 26.

Next, the operation of the ignition timing control device configured as described above will be explained with reference to FIGS. 2 and 3.

In this ignition timing control device, the ignition circuit 2
Switching control between the calculation ignition control via the ignition circuit 29 and the fixed ignition control via the fixed ignition circuit 29 is performed depending on the operating state of the engine, etc., as will be described later.
First, with reference to Fig. 2, ignition control during normal operation (calculated ignition control) and fixed ignition control performed during predetermined operation will be explained, and then with reference to Fig. 3, calculation ignition control and fixed ignition control will be explained. The switching procedure will be explained.

First, calculation ignition control is performed as follows. That is, the CPU 10 receives T ₀₄ from the T ₀₄ sensor 17.
Based on the signal and the T ₂₄ signal from the T ₂₄ sensor 16,
The crank angle stage (hereinafter simply referred to as "stage position") from the reference crank angle position of each cylinder is detected. That is, for example, T ₀₄ in FIG.
The T ₂₄ signal pulses S ₄₀ and S ₂₀ (FIG. 2b) detected immediately after the signal pulses Sa ₄ and Sa ₂ occur, for example, at the end of the compression stroke of the fourth and second cylinders, respectively.
If it occurs at the TDC position, CPU10
The reference crank angle position (TDC position) of the fourth cylinder is detected by the _T24 signal pulse _S40 input immediately after the generation of the _T04 signal pulse _Sa4 , and the reference crank angle position of the fourth cylinder and the subsequent second crank angle position are detected. The position of the first crank angle among the six divided crank angles between the reference crank angle positions of the cylinder, that is, the 0th stage position (the period between the rising points of pulses S ₄₀ and S ₄₁ in FIG. 2b is defined as the 0th stage) (Defined as position (hereinafter the same)) is detected. When this 0th stage position is detected, the subsequently input T ₂₄ signal pulses S ₄₁ , S ₄₂ . . .
Detect stage position... And CPU10
is the time interval of each stage, that is, the time interval ME _6i of each pulse generation of the T ₂₄ signal is measured with a clock pulse of a predetermined period, and the measured ME _6i values of each stage are added to calculate the Me value (=ME ₆₀ + ME ₆₁ ＋…＋ _ME65 ）
seek. This Me value is used for calculating the engine rotation speed Ne, etc.

The CPU 10 is located at a predetermined stage position (for example, the first
When the stage position) is detected, the ignition advance angle θIG, ignition coil energization time DUTY, etc. are calculated based on the output signals from the various parameter sensors described above. The ignition advance angle θIG is calculated based on the following equation (1).

θIG=θ _MA p+θIGCR ...(1) Here, the ignition advance angle θIG is expressed as the crank angle from the reference crank angle position (for example, the crank angle position at which the _T24 signal pulse _S20 in FIG. 2b is generated),
θ _MA p is the basic ignition advance angle, and its value is a parameter representing the engine speed Ne and engine load,
For example, it is given as a function of the intake pipe absolute pressure P _BA . Specifically, the Ne-
From the P _B -θIG map, a value corresponding to the detected absolute pressure value P _BA and the detected engine speed value Ne is read out as the θ _MA p value. Note that the engine speed Ne is calculated as the reciprocal of the value Me obtained as described above.
θIGCR is another advance/retard angle correction amount, and is determined by engine coolant temperature Tw, intake air temperature T _A , and the like.

Next, the CPU 10 calculates the energization time DUTY of the primary coil 22a of the ignition coil 22. This energization time DUTY is set to an optimal value in order to prevent both coil heating and spark plug misfire prevention, and is generally determined as a function of engine speed Ne, and the determined value is corrected by battery voltage V _B. .

Next, the CPU 10 controls the primary coil 2 from the ignition advance angle θIG and energization time DUTY obtained as described above.
2a energization start time TDUT and energization stop time
Calculate TIG. First, ignition advance angle θIG, energization time
Calculate backward from the reference crank angle position the crank angle position at which energization should start from DUTY to the primary coil 22a (the position corresponding to time t ₁ in Figure 2 c), and determine at which stage position this crank angle position at which energization should start. Determine whether Then, the determined stage position (#2 stage position in the illustrated example) is
The time required for the rotation of the crankshaft to reach the crank angle position at which energization should start is determined from the time t ₀ (FIG. 2 c) when the T ₂₄ signal pulse is input, and this time is defined as the energization start time TDUT. Similarly, it is determined from the ignition advance angle θIG which stage position is the crank angle position (the position corresponding to time _t3 in FIG. 2c) at which the energization of the coil 22a should be stopped. Then, the time required for the rotation of the crankshaft to reach the crank angle position at which energization should be stopped is determined from time t ₂ when the T ₂₄ signal pulse at the determined stage position (#4 stage position in the illustrated example) is input. The time is defined as the energization stop time TIG.

When the CPU 10 detects the T ₂₄ signal pulse (S ₄₂ ) at the stage position where the coil 22a should start energizing (time t ₀ ), the CPU 10 waits for the energization start time TDUT to elapse using the energization counter provided inside the CPU 10. , an energization control signal is supplied to the drive circuit 20 at the time when the energization start time TDUT has elapsed (time _t1 ). Then, from the time when the T ₂₄ signal pulse (S ₄₄ ) at the stage position where the energization of the coil 22a should be stopped (at time t ₂ ), the energization stop counter provided inside the CPU 10 determines the energization stop time.
Wait for TIG to elapse, and stop supplying the energization control signal to the drive circuit 20 when the energization stop time TIG has elapsed (time _t3 ).

The drive circuit 20 supplies coil energizing power to the primary coil 22a of the ignition coil 22 via the switching circuit 21 while being supplied with the energization control signal from the CPU 10. When the supply of coil energizing power from the drive circuit 20 is cut off, a high voltage is generated on the secondary coil 22b side of the ignition coil 22, and this high voltage is transmitted to the ignition plug (in the illustrated example) via the power distributor 24. The spark plug 25c) is supplied with the spark plug 25c), at which a spark discharge, ie, ignition, occurs.

Further, fixed ignition control is performed via the fixed ignition circuit 29 and the switching circuit 21. That is, the crank angle positions indicated by the falling and rising points of the T ₀₄ signal pulse are set as the energization start time and the energization stop time, respectively, and the primary coil 22a of the ignition coil 22 is energized for a time corresponding to the pulse width T. It supplies power and controls ignition timing based on the crank angle position indicated by the T ₀₄ signal.

This fixed ignition control is performed under a predetermined engine condition in which the above-mentioned calculated ignition control cannot be performed, that is, during a predetermined period at the time of engine startup, when the intake pipe absolute pressure (P _BA ) sensor 12
This is performed after a failure or the like of the CPU 10 has been detected and initialized.

Next, the switching control procedure between the calculated ignition control and the fixed ignition control will be explained with reference to FIG. The control procedure program shown in FIG. 3 is executed every time the T ₀₄ signal is generated.

First, in the first step 31, it is determined whether stage #0 is detected or not, that is, immediately after the rise of the _T04 signal.
It is determined whether the _T24 signal has been detected.
As described above, stage #0 is the starting point for detecting the engine rotation speed, which is a basic parameter when performing computational ignition control. However, the engine starts from an arbitrary crank angle position of the crankshaft at the time of engine startup or initialization at the time of CPU runaway. Therefore, first, it is determined whether or not stage #0 is detected. If the determination result is negative (No), this program is terminated, and if the determination result is affirmative (Yes), the program proceeds to the next step 32.

In step 32, it is determined whether or not the detected engine speed NE is equal to or higher than a predetermined judgment speed IGCNE. If the result of the determination is negative (No), the process proceeds to step 35 (fixed ignition control), and if the result is affirmative (Yes). )
If so, proceed to step 33. Here, the predetermined discrimination rotation speed IGCNE is the discrimination value IGCNEH (for example,
Two discrimination values are set, the discrimination value IGCNEH (650 rpm) and the discrimination value IGCNEH (for example, 350 rpm).
(650 rpm) is used when changing from fixed ignition control to calculated ignition control, and the discrimination value IGCNEL (350 rpm) is used when changing from calculating ignition control to fixed ignition control. The reason why the hysteresis characteristic is set to the engine speed for determining the engine speed, which is one of the conditions for switching between the fixed ignition control and the calculated ignition control, is as follows.

In order to set the ignition timing in computational ignition control, it is necessary to be able to stably detect the engine speed, and as described above, this engine speed depends on the time interval of generation of the _T24 signal pulse.

However, in the early stages of engine startup, the engine temperature is low, so the crankshaft does not rotate smoothly due to the effects of the viscosity of the engine oil and the sliding resistance of various parts of the engine, and the time intervals at which the T ₂₄ signal pulses are generated become irregular, resulting in inaccurate It is difficult to detect the engine speed. Therefore, even if the crankshaft does not rotate smoothly when starting the engine, the engine is operated using fixed ignition control that ensures ignition when the crankshaft reaches a predetermined angle position, and the engine speed remains stable. When the engine speed rises to near the idling speed that can be detected in
The rotation speed was set at 650 rpm.

On the other hand, when switching from computational ignition control to fixed ignition control, that is, when the engine speed changes from an operating state where the engine is rotating stably to a state where the engine speed is lower, for example, when the engine speed changes to a lower speed that is temporarily induced by an electrical load, etc. In this case, the engine speed can be accurately detected until it reaches a lower value than at the time of starting, so in this case, a value lower than the above-mentioned discrimination value IGCNEH is detected.
Calculated ignition control allows operation to continue with optimal ignition timing up to IGCNEL (for example, 350 rpm).

Next, in step 33, the detected value of battery voltage is
It is determined whether or not V _B is greater than or equal to a predetermined value IGCEVB (e.g. 8V), and if the determination result is negative (No), proceed to step 35 (fixed ignition control), and if affirmative (Yes), proceed to step 34. Proceed to. That is, for example, when starting the engine, the battery voltage may drop rapidly due to starter operation immediately after starting, and then recover. If the battery voltage at the time of recovery is below the discrimination value IGCEVB (e.g. 8V), Fixed ignition control (step 35) is performed, and if the battery voltage is greater than the determination value IGCEVB, calculation ignition control (step 36) is performed through the determination of step 34, which will be described later.

In computational ignition control, as mentioned above, when calculating and setting the ignition timing, the battery voltage V _B is detected,
The energization time of the ignition coil 22 is corrected according to the battery voltage to prevent misfires due to insufficient ignition energy. However, if the switch is made to computational ignition control when there is a large change in battery voltage when starting the engine, there is a possibility that ignition energy will be insufficient during the set energization time and a misfire will occur. On the other hand, fixed ignition control energizes the ignition coil over a time interval corresponding to the pulse width T of the T ₀₄ signal.
The time interval corresponding to the pulse width T becomes longer as the engine speed decreases. In other words, by setting the pulse width T of the T ₀₄ signal to an appropriate size, even if the battery voltage is low enough to cause a misfire with computational ignition control, fixed ignition control can achieve ignition that does not cause a misfire. This means that energy can be supplied.

Next, in step 34, it is determined whether the calculation of the ignition advance angle θIG necessary for the calculation ignition control has been completed.
This determination is made based on the number of occurrences of the T ₀₄ signal.
That is, in order to calculate the ignition advance angle θIG, it is first necessary to determine the engine speed. By the way, in order to accurately determine the engine speed, the ME _6i value at each stage from #0 to #5 must be detected, and this requires that the crankshaft is at least
Must be rotated by 1 TDC interval (180°). Then, calculation of the ignition advance angle is executed at a predetermined stage (for example, #0 stage) between the TDC position when the engine rotates by 1 TDC interval and the next TDC position. Therefore, the number of elapsed TDC positions is monitored based on the number of occurrences of the T ₀₄ signal, and if the number of occurrences of the T ₀₄ signal reaches a predetermined number (for example, 2) after step 34 is executed for the first time, and the engine rotational speed obtained during this period is When the calculation of the ignition advance angle θIG is completed based on Ne, it is determined that the calculation of the ignition timing is completed. This step
If the result of the determination in step 34 is affirmative (Yes), the process proceeds to step 36, where calculation ignition control is executed, and if the result is negative (no), the process proceeds to step 35, where fixed ignition control is continued.

(Effects of the Invention) As described in detail above, according to the ignition timing control device for an internal combustion engine of the present invention, the first ignition control means for controlling the energization of the ignition coil based on the ignition timing set by calculation, and the crankshaft A switching control means that performs switching control with a second ignition control means that controls energization of the ignition coil depending only on the angle signal,
It is determined which of the first and second ignition control means should be switched in accordance with a plurality of operating parameters including at least the engine rotation speed and the power supply voltage of the power source that supplies electric power to the ignition coil. , the switching control can be executed accurately and misfires can be prevented. Further, when it is determined that control should be switched from the second ignition control means to the first ignition control means, a predetermined number of times corresponding to a period sufficient to at least calculate a stable engine rotational speed from the time of the determination means. After the crank angle signal is generated, the switching control is performed by the first ignition control means, and the setting of the ignition timing is completed during a period in which the predetermined number of crank angle signals are generated by the first ignition control means. Therefore, more appropriate ignition timing can be obtained, and driving performance when switching ignition control can be improved.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing the configuration of the ignition timing control device according to the present invention, Fig. 2 is a timing chart showing how the T ₀₄ signal and T ₂₄ signal are generated, and the calculation timing of the ignition advance angle θIG, etc.; The figure is a flowchart showing the switching control procedure. 10...CPU, 14...V _B sensor, 16...
T ₂₄ sensor, 17... T ₀₄ sensor, 20... Ignition circuit, 21... Switching circuit, 22... Ignition coil,
29...Fixed ignition circuit.

Claims (1)

[Claims] 1. A first ignition control means that controls energization of an ignition coil based on ignition timing set to an optimal value for engine operating conditions according to operating parameters of the internal combustion engine, and detects at least one predetermined crank angle position of the engine crankshaft. a crank angle position detecting means for generating a crank angle signal; a second ignition control means for controlling energization of the ignition coil depending only on the crank angle signal;
and a switching control means for controlling switching to either one of the second ignition control means, the switching control means comprising:
and a determining means for determining which of the first and second ignition control means should be switched to in accordance with a plurality of operating parameters including at least engine rotational speed and a power supply voltage of a power source that supplies electric power to the ignition coil. At the same time, the determination means determines the second
When it is determined that control should be switched from the ignition control means to the first ignition control means, a predetermined number of said crank angle signals corresponding to a period sufficient to calculate at least a stable engine rotational speed from the time of said determination. is characterized in that the switching control is performed by the first ignition control means after the occurrence of , and the setting of the ignition timing is completed during a period in which the predetermined number of crank angle signals are generated by the first ignition control means. Ignition timing control device for internal combustion engines.