JPH01285661A - Ignition device for internal combustion engine - Google Patents

Abstract

PURPOSE:To resolve the long excitation time of an ignition coil by nullifying the calculated ignition timing and exciting the ignition coil synchronously with the rotation angle immediately before the top dead point or at the top dead point of each cylinder when an internal combustion engine is rotated at an extremely low speed. CONSTITUTION:Detection signals from a rotation angle sensor 2 provided on the crank shaft of an internal combustion engine and a reference angle sensor 3 are inputted to an MPU 5 via the wave-form shaping circuit 4 of an ECU 1 respectively to perform the preset calculation. An ignition signal is generated by a backup circuit 6 in response to the calculation result, the generated ignition signal is inputted to the power transistor 13 of an igniter 12, the primary current is fed to an ignition coil 15 from a power source V. In this case, when the rotating speed of the internal combustion engine is extremely low, the MPU 5 nullifies the calculated ignition timing and starts the excitation of the ignition coil 15 synchronously with the rotation signal immediately before the top dead point or at the top dead point of each cylinder. The excitation is completed after the elapse of the preset time.

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to an ignition device for an internal combustion engine that controls the primary current of an ignition coil using an output signal from a calculation means that calculates the optimum energization time and ignition timing according to the operating state of the internal combustion engine. More specifically, the present invention relates to an ignition device for an internal combustion engine that satisfactorily controls the primary current of an ignition coil when the engine's rotational speed is extremely low.

[Conventional technology]

Conventionally, in an electronic advance type ignition system installed in an internal combustion engine, at low speeds where rotational fluctuations are large, energization to the primary side of the ignition coil is started in synchronization with the output edge of the rotational angle signal, and the next rotational angle is Since it is designed to end at the output edge of the signal (just before top dead center), when starting the engine,
There was a problem in that the energization time was too long at extremely low engine speeds just before the engine stalled, resulting in increased heat generation in the power transistor that made up the igniter and the ignition coil. Furthermore, if the engine stalls immediately after starting energization of the ignition coil when the engine is running at extremely low rotation speeds, there is a problem in that the next output edge of the rotation angle signal is not detected and energization is not terminated. For this reason, the conventional ignition system
No. Publication, Nippon Denso Technical Report 37-058 and 56-07
As shown in No. 9, a device is disclosed in which the energization is terminated after a predetermined period of time has elapsed after the start of energization of the ignition coil, thereby preventing the power transistor of the igniter and the ignition coil from generating heat. [The problem that the invention tries to solve! ! ! ! ] However, Special Publication No. 62-37231, published by Nippondenso, $137-
In the conventional ignition devices shown in Nos. 058 and 56-079, which limit the energization time to a predetermined time, if the energization time is too short, it may cause premature ignition when starting the engine at a low temperature or at extremely low rotation speeds just before the engine stalls. In order to cause ignition, the energization time must be set to about 50W or more. However, setting the energization time to about 50 m or more will lengthen the constant current control time by the igniter and increase the heat generation of the power transistor.To solve this problem, the power transistor should be made with excellent heat resistance. In addition, the ignition coil must have a large primary resistance, which poses a problem in that it poses a major restriction on the design of the ignition device. This invention was made to solve the above problems, and its purpose is to eliminate the long energization time of the ignition coil when the internal combustion engine is running at extremely low speeds, and to shorten the constant current control time to configure the igniter. It is possible to reduce the heat generation of the power transistor, thereby making the power transistor inexpensive, and to reduce the heat generation of the coil by making the ignition coil have a small primary resistance.
Another object of the present invention is to provide an ignition device for an internal combustion engine that can improve the ignition performance by making the ignition coil have a small primary resistance so that the primary current rises quickly at high rotation speeds. [Means for Solving the Problems 1] In order to achieve the above object, the present invention includes a rotation angle sensor that detects the rotation of an internal combustion engine and outputs a rotation angle signal at a predetermined rotation angle position, and the rotation angle signal and the internal combustion engine. a calculation means for calculating the energization time and ignition timing of the ignition coil according to the operating state of the ignition coil and outputting a signal; and an igniter for controlling the primary current of the ignition coil based on the output signal from the calculation means. In an ignition system for an internal combustion engine, when the rotational speed of the internal combustion engine is a predetermined extremely low rotational speed, the ignition timing by the calculation means is disabled and synchronized with a rotation angle signal from just before top dead center to at top dead center of each cylinder. The gist of the invention is an ignition device for an internal combustion engine, which includes a fixed ignition means that starts energizing an ignition coil and then stops energization after a predetermined period of time. [Operation] Therefore, as the internal combustion engine rotates, the rotation angle sensor outputs a rotation angle signal at a predetermined rotation angle position, and the calculation means calculates the ignition coil energization time and ignition timing based on the rotation angle signal and the operating state of the internal combustion engine. is calculated. Then, based on the output signal from the calculation means, the ignition coil is activated by the igniter.
The next current is controlled. In addition, when the rotation speed of the internal combustion engine is extremely low, the ignition timing calculated by the calculation means is invalidated by the fixed ignition means, and the rotation angle signal from just before top dead center to at top dead center of each cylinder The energization of the ignition coil is started in synchronization with the ignition coil, and the energization is ended after a predetermined period of time has elapsed.

【Example】

An embodiment embodying the present invention will be described below with reference to FIGS. 1 to 15. Figure 1 shows the electrical schematic configuration of the ignition system, and shows the control device (
An electromagnetic pickup type rotation angle sensor 2 and a reference angle sensor 3 are connected to the ECU (hereinafter referred to as ECU) 1, which detects the rotation angle of the crankshaft built in the distributor. A rotation angle signal is output at every angle (30@ in this embodiment), and the reference angle sensor 3 outputs a reference angle signal at a predetermined crank angle before the top dead center of each cylinder of the engine. In this embodiment, the rising edge of the reference rotation angle signal NE is set near BTDC (before top dead center) 10@. The output signals of both the sensors 2 and 3 are sent to a waveform shaping circuit 4.
4(a), using the same waveform shaping circuit 4.
As shown in (b), the waveform-shaped rotation angle signal NE and reference angle signal G are inputted to a microcomputer (hereinafter referred to as MPU) 5 as a calculation means and fixed ignition means. The MPU 5 is a read-only memory (ROM) in which arithmetic circuits, control programs, and initial data are stored in advance.
, and a random access memory (RAM) in which various signals input to the MPU 5 and data required for arithmetic control are temporarily stored. from various sensors that detect the engine speed and various operating conditions of the internal combustion engine, such as an intake air amount sensor that detects the intake air amount, a cooling water temperature sensor that detects the cooling water temperature, and a battery voltage sensor that detects the battery voltage. The ignition coil energization time and ignition timing are calculated based on the human input signal, and the output signal IG
t (MPU). The output signal IGt (MPU) of the MPU5 is the ignition signal I
It is input to the bank up circuit 6 as an ignition signal generating means that outputs Gt, and this bank up circuit 6
A rotation angle signal NE and a reference angle signal G are input to the . As shown in FIG. 2, the backup circuit 6 includes a backup ignition signal generation circuit 7 and a fail determination circuit 8. As shown in FIG. 3, the bank-up ignition signal generation circuit 7 includes a fixed edge ignition signal generation circuit 9 and a fixed width ignition signal generation circuit 10 to which the rotation angle signal NE and reference angle signal G are input, and a signal switching circuit. It consists of 11. Based on the rotation angle signal NE and the reference angle signal G, the fixed edge ignition signal generation circuit 9 generates a high signal at the rising edge of the rotation angle signal NE before the top dead center of each cylinder, as shown in FIG. 4(C). level, and a fixed edge ignition signal B which becomes low level at the rising edge of the rotation angle signal NE near top dead center (TDC) is output. Further, the fixed width ignition signal generation circuit 10 generates a rotation angle signal NE near the top dead center (TDC) of each cylinder, as shown in FIG. 4(e), based on the rotation angle signal NE and the reference angle signal G.
It becomes high level at the rising edge of
In this embodiment, a fixed-width ignition signal C that becomes low level after five (5) lapses is output. Then, the signal switching circuit 11 determines the engine speed based on the input period of the rotation angle signal NE, that is, the interval between rising edges. The period is 17m
If the engine speed is less than 300 rpm (input cycle is 17 or more), the fixed edge ignition signal B is output as the ignition signal IGt (B/U), and if the engine rotation speed is less than 300 rp- (the input cycle is 17 or more), the fixed edge ignition signal C is output. Ignition signal IGt (B/U)
It is designed to be output as . The fail judgment circuit 8 of the backup circuit 6 receives the output signal IGt (MPU), the ignition signal IGt (B/U), the rotation angle body number NE, and the reference angle signal G, and the fail judgment circuit 8 receives the rotation angle signal NE. A failure of the MPU 5 is determined based on how many pulses of the output signal IGt (MPU) are input while a predetermined number of pulses are inputted, and if it is determined that the MPU 5 is normal, the output signal IGt (MPU) is
) is selected and output as the ignition signal IGL, and when the MPU 5 determines that there is an abnormality, it selects the ignition signal IGt' (B/U) output from the backup ignition signal generation circuit 7 and outputs it as the ignition signal IGt. It is designed to be output. An igniter 12 is connected to the fail determination circuit 8, and an ignition signal IGt is input to the base terminal of a power transistor 13. power transistor 13
The collector terminal of is connected to one end on the primary side of an ignition coil 15 that supplies ignition energy to an ignition power lug 14 provided for each cylinder of the engine. Then, the igniter 12 turns on the power transistor 13 in synchronization with the rising edge of the ignition signal IGt, causes the primary current 1 to flow from the power supply 1 to the ignition coil 15, and in synchronization with the falling edge of the ignition signal IGt. Turn off the power transistor 13, and the primary current! 1 and generates a secondary voltage. Next, the processing executed by the MPU 5 in the ignition device configured as described above will be explained according to the flowcharts shown in FIGS. 5-8. Note that this is a six-cylinder engine in which the rotation angle signal NE is input at every 30° crank angle. First, in step 1 (hereinafter simply referred to as 81) of the main loop shown in FIG. 5, the MPU 5 calculates the engine rotation speed NEI based on the rotation angle signal NE of the rotation angle sensor 2, and also calculates the engine rotation speed NEI based on the intake air amount sensor. Calculate engine load. Also, the battery voltage is calculated based on the input signal from the battery voltage sensor. In S2, it is determined whether the NEI calculated in S1 is less than the rotation speed NEFIX (300 rpm in this example) at which fixed ignition is performed, and the NEI is determined to be NEFIX.
If it is determined that the NEI is greater than or equal to EFIX, the process proceeds to S3 and the fixed ignition instruction flag
Proceeding to S4, the fixed ignition instruction flag XFIX is set to "1", that is, fixed ignition. Then, proceeding to S5, the ignition timing is calculated based on the engine speed NEI and engine load calculated in S1, and in the next <36, the NEI and battery The energization time t(1) of the ignition coil is determined based on the voltage. Also, the MPU 5 executes an interrupt process as shown in FIG. 6 every time the rotation angle signal NE from the rotation angle sensor 2 is input.511 It is determined whether the counter value of the top dead center discrimination counter CTDC at the time of the previous interruption is "4", that is, whether the interruption is at the top dead center (TDC) of each cylinder.
If the interrupt is at the top dead center, proceed to S12 and set the current counter value to "1"; if it is an interrupt other than the top dead center, proceed to S13 and set the current counter value to rCTDC+IJ and set it to 31.
Proceed to step 4. At step 314, it is determined whether the fixed ignition instruction flag XFIX is "1", that is, whether the engine rotation speed NEI is less than 300 rpm. If it is determined that XFIX is "1", the process proceeds to step 315, where fixed ignition processing is performed. On the other hand, when 314 determines that XFIX is "0", 3 is executed.
After proceeding to S16 and executing normal ignition processing, another interrupt processing is executed at S17, and the process returns to the main loop. In the fixed ignition process in S15, as shown in FIG. 7, it is determined whether the counter value CTDC is rlJ, that is, in S21, it is determined whether the interruption occurs at the top dead center of each cylinder, and if it is determined that it is not "1". Ends this routine without performing any processing. If it is determined in step 321 that the counter value CTDC is "1", that is, that the interruption occurs at the top dead center of each cylinder, the process advances to step S22, where the rotation angle signal N is output as shown in FIG.
The ignition signal IGt is output at the rising edge of E. Then, in S23, as shown in FIG. 1θ, time t1 of a free running timer built in the MPU 5 is stored in the RAM as the energization start time. Continuation (In S24, as shown in FIG. 8, when the time set in the interrupt generation register and the time measured by the free running timer match, the ignition signal IGt for ending energization is generated.
After making preparations for outputting the end of energization to the IGt output port so as to output , a time t2 is obtained by adding the energization time tQ calculated in S6 of the main loop to the energization start time t1 stored in the above S23 in the interrupt generation register. Set. Then, when the time of the free running timer coincides with the time t2 entered in the ignition generation register, the ignition signal IGt is set to a low level as shown in FIG. 1O, and the energization is terminated. In this way, when it is determined that the rotation speed NEI calculated based on the rotation angle signal NE during normal operation of the MPU 5 is less than the extremely low rotation (300 rpm) at which fixed ignition is performed, the M
PU5 switches from normal ignition processing to fixed ignition processing. Then, energization is started at the rising edge of the rotational angle signal NE just before the top dead center of each cylinder, and the engine rotational speed NEI
Since the energization is terminated after the energization time t (1) determined based on the battery voltage and battery voltage, premature ignition is prevented, and the starter is prevented from locking, reversing, and knocking due to reverse torque, and operating performance is maintained. Next, the ignition process at the time of failure of the MPU 5 is described in Section 4.11.
This will be explained according to Figures 15 to 15. The fail judgment circuit 8 determines the number of pulses of the rotation angle signal NE and MP
If it is determined that the MPU5 is malfunctioning based on the number of pulses of the output signal IGt (MPU) of U5, the ignition signal IGt output from the backup ignition signal generation circuit 7
(B/U) is selected and output as the ignition signal IGt. At this time, the signal switching circuit 11 determines the engine speed based on the input cycle of the rotation angle signal NE, that is, the interval between rising edges, and determines that the engine speed is extremely low just before stalling, that is, 300 rpm or more (input cycle is less than 17w)
In this case, as shown in Fig. 4(C), the rotation angle signal NE becomes high level at the rising edge of the rotation angle signal NE before the top dead center of each cylinder, and the rotation angle signal NE near the top dead center (TDC) becomes high level. The fixed edge ignition signal B which becomes low level at the rising edge of is outputted to the fail judgment circuit 8 as the ignition signal IGt (B/U). In addition, the signal switching circuit 11 is used when the engine rotation speed is less than 30 Orpm (the input cycle is made by 17 or more).
In this case, as shown in Figure 4 (81), the top dead center of each cylinder (
The ignition signal IGt (B/ It is output to the fail judgment circuit 8 as U). When this MPU 5 is out of order, for example, when starting electricity at extremely low rotation speeds (for example, 10,100 rpm) at the rising edge of the two rotational angle signals NH just before the top dead center of each cylinder shown in FIG. The rising edge of the reference rotation angle signal NE is BTDC (before top dead center) lO
Since it is set near e, the energization time becomes as long as 50 - as shown in FIG. 12, and the temperature of the power transistor 13 increases as is clear from the graph shown in FIG. 13. That is, the heat generated by the transistor 13 increases. In order to prevent this heat generation, if the ignition coil 15 is turned off in 10+ seconds after starting, the BTDC will be approximately 3.
The ignition occurred at 4 degrees (-30 degrees This may cause the starter to lock, reverse rotation, or cause non-king. However, when the MPU 5 fails and the engine is at extremely low rotation speed, the signal switching circuit 11 causes the rotation angle signal NE of BTDCI Oo to change for a predetermined period of time (5 m in this embodiment) from the reference edge of the rotation angle signal NE, as shown in FIG. 11(C). As shown in Figure 15, the engine's required advance angle is near top dead center (TDC), which prevents premature ignition and prevents the starter from locking due to reverse torque.
Reverse rotation and knocking are prevented and driving performance is maintained. In this way, in this embodiment, even when the MPU 5 is normal,
In addition, even when the MPU 5 is abnormal, if the engine speed becomes less than an extremely low speed (300 rpm), ignition is activated for a predetermined period of time at the rising edge of the reference rotation angle signal NE just before top dead center of each cylinder. Since the coil is energized, even if the engine stalls after the ignition coil 15 starts to be energized, the heat generated by the power transistor 13 that constitutes the igniter 12 is reduced, thereby making the power transistor 13 less expensive. At the same time, the ignition coil 15 can be made to have a small primary resistance to reduce coil heat generation. Further, by making the ignition coil 15 have a small primary resistance, the rise of the primary current during high rotation can be accelerated, thereby improving the ignition performance. In the above embodiment, an ignition device was described in which the rotation angle sensor 2 that outputs a rotation angle signal every 30@crank angles was used and the ignition signal IGt was output based on the reference angle signal of the reference angle sensor 3. As shown in Figure 16, the ignition system uses a rotation angle sensor that outputs a rotation angle signal near the top dead center of each cylinder without using a reference angle signal, and in the same way as above, the engine rotation speed (or rotation angle signal The ignition signal may be switched between a fixed-width ignition signal and a fixed-width ignition signal depending on the input period (input period). Also, in the above embodiment, a 6-cylinder engine was described, but
It goes without saying that this method can be applied to engines such as 3.4 cylinders. [Effects of the Invention] As detailed above, according to the present invention, the long energization time of the ignition coil during extremely low rotation of the internal combustion engine is eliminated, the constant current control time is shortened, and the heat generated by the power transistor constituting the igniter is reduced. As a result, the power transistor can be made inexpensive, and the ignition coil can be made with a small primary resistance to reduce coil heat generation; This has the excellent effect of accelerating the rise of the primary current at high rotation speeds and improving ignition performance.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the electrical configuration of an embodiment embodying the present invention, FIG. 2 is a block diagram showing a backup circuit, FIG. 3 is a block diagram showing a backup ignition signal generation circuit, and FIG. 4 5 is a flow chart showing the main routine executed by the microcomputer, and 6 is a waveform diagram for explaining the action during backup.
The figure is a flowchart showing interrupt processing using rotation angle signals.
Fig. 7 is a flowchart showing fixed ignition processing, Fig. 8 is a flowchart showing ignition time energization end cent processing, Fig. 9 is a map of energization time using power supply voltage and engine speed as parameters, and Fig. 10 is MPU 11 is a waveform diagram for explaining the fixed ignition process executed by
The figure is a graph showing the relationship between the engine speed and the input period of the rotation angle signal, Figure 13 is a graph showing the relationship between the ignition coil energization time and the temperature of the power transistor, and Figure 14 is the graph showing the relationship between the engine speed and the fully closed Fig. 15 is a graph showing the relationship between the engine speed and the ignition timing, and Fig. 16 is a graph showing the relationship between the engine speed and the ignition timing. It is. In the figure, 2 is a rotation angle sensor, 3 is a reference angle sensor, 5 is a microcomputer as calculation means and fixed ignition means,
12 is an igniter, and 15 is an ignition coil. Patent applicant: Nippondenso Co., Ltd. Agent: Patent attorney On 1) Hironobu Figure 6 Figure 10 1-cylinder TDC 5-cylinder TDC

Claims (1)

[Scope of Claims] 1. A rotation angle sensor that detects the rotation of the internal combustion engine and outputs a rotation angle signal at a predetermined rotation angle position; An ignition device for an internal combustion engine, comprising a calculation means for calculating ignition timing and outputting a signal, and an igniter for controlling a primary current of an ignition coil based on the output signal from the calculation means, comprising: a rotation speed of the internal combustion engine; is at a predetermined extremely low rotation, the ignition timing by the calculation means is disabled and energization of the ignition coil is started in synchronization with the rotation angle signal from just before top dead center to top dead center of each cylinder, and then An ignition device for an internal combustion engine, comprising a fixed ignition means that terminates energization after a certain period of time.