JP2531189B2 - Ignition device for internal combustion engine - Google Patents

Description

The present invention relates to an ignition device for an internal combustion engine, and particularly when the ignition coil is continuously energized, the ignition coil is forcibly turned off after being energized for a predetermined period. It was done like this.

[Conventional technology]

Conventionally, as disclosed in JP-A-57-65867,
There is known a method in which the control result performed earlier is fed back to control the energization to the subsequent ignition coil so that the energization time to the ignition coil becomes a required optimum energization time.
Further, in this conventional technique, when the duration of energization after the start of energization of the ignition coil exceeds a predetermined time, the primary current of the ignition coil is forcibly and gently cut off to prevent spark generation and circuit protection. It is disclosed that the cutoff state is continued by performing the operation and forcibly holding the detected current value large.

Further, in Japanese Patent Application Laid-Open No. 55-46030, a spark is generated by forcibly and gently interrupting the primary current of the ignition coil when the duration of energization after the start of energization of the ignition coil exceeds a predetermined time. What protects a circuit while preventing is disclosed.

Further, as disclosed in Japanese Patent Laid-Open No. 55-25558, by feeding back the charging voltage of the capacitor, which indicates the time of constant current control of the primary current of the ignition coil, the ignition coil 1 can be operated regardless of whether the battery voltage is high or low. It is known that feedback control is performed so that the period during which the next current reaches a predetermined current is a constant optimum time.

[Problems to be solved by the invention]

Since the above-mentioned forced cutoff of the primary current is performed to protect the semiconductor switching element such as the power transistor that controls the primary current of the ignition coil, the energization duration can be within the range allowed by the element. It is desirable to set it as short as possible. However, on the other hand, in order to ensure startability at a low cranking speed, a certain degree of forced shutoff is not performed before the normal ignition timing is reached at an extremely low speed such as when the internal combustion engine is started. It is desirable to set it for a long time.

In this way, the time until forced shutoff is set within a limited range that satisfies the contradictory conditions.
In the prior art disclosed in JP-A-55-46030 or JP-A-55-46030, since the time from the start of energization of the ignition coil is measured, the regular ignition timing arrives at a low rotational speed such as 20 rpm at the time of starting. Forced shutoff before
There is a problem that a high cranking speed is required for starting.

Further, in the conventional technique disclosed in Japanese Patent Laid-Open No. 55-25558, when the primary current of the ignition coil is cut off, the capacitor that generates a voltage signal according to the time of the constant current control starts discharging. There is a problem that the voltage signal fed back is reduced again and the subsequent energization time cannot be optimized.

Further, in view of the fact that the forced shutoff shown in the above-mentioned conventional technique mainly occurs after the engine stall, there is a possibility that the restart of the engine after the engine stall is not properly performed in the configuration of the above-described conventional technique. For example, if an engine stall occurs at a relatively high rotation speed of about 1000 rpm and forced shutoff is performed, the power supply start timing will be delayed by feedback control that attempts to shorten the power supply time at the subsequent restart, but that power supply start Since the timing is based on the energization time information in the high rotation state immediately before the engine stall, the energization start timing is for the restart performed at an extremely low speed such as 20 rpm where the engine speed is much lower than that at the engine stall. There is a problem in that the ignition spark is not properly set, and the ignition spark having the required intensity cannot be obtained at the required ignition timing.

Therefore, in view of the problems of the above-mentioned conventional techniques, the present invention realizes excellent startability and, even when the energizing current of the ignition coil is forcibly cut off due to engine stall or the like, good startability at the time of restart immediately thereafter. The purpose is to secure.

[Means for solving problems]

In order to achieve the above object, the present invention is an internal combustion engine that controls energization to the ignition coil in combination with an ignition signal generation circuit (1) for obtaining an optimal energization time of the ignition coil and generating an ignition signal indicating an energization period. In the ignition device for a vehicle, control means (3, 4, 5, 7) for intermittently energizing the ignition coil in response to the ignition signal and limiting an energizing current to the ignition coil to a predetermined value, Feedback signal generating means for detecting that the current supplied to the ignition coil is limited to a predetermined value by the control means, generating a feedback signal indicating the duration of the current limiting state, and feeding back the feedback signal to the ignition signal generating circuit. (8) and configured to start time measurement in response to the feedback signal and reset time measurement in response to the ignition signal. When the current limiting state is determined to have continued for a predetermined time or more, the energizing current to the ignition coil is further reduced from the current limiting state by the control means to interrupt the energizing current. A timer means (6) for continuing the generation of the feedback signal to the ignition signal generating circuit even in this energization cutoff state, canceling the energization cutoff state in response to the disappearance of the ignition signal, and stopping the feedback signal. ) And a technical means called an ignition device for an internal combustion engine.

The control means detects a current supplied to the ignition coil and outputs a detection current signal to a detection circuit (5) and compares the detection current value by the detection circuit with a predetermined value,
And a current control means (7) for outputting an energization limit signal when the detected current value exceeds a predetermined value, wherein the feedback signal generating means outputs the feedback signal in response to the energization control signal of the current control means. , It is determined that the feedback signal has continued for a predetermined time or more with the detected current value output by the timer means and input to the current control means as an excessive current value, and in particular, the energization limit signal is continuously output. Can be configured to.

The numbers given in parentheses are reference numerals of the corresponding configurations of the embodiments described later.

In the embodiments described later, the above control means includes a power transistor 3 as a semiconductor switching element that controls the current supplied to the ignition coil, a drive circuit 4 that drives the power transistor 3, and a current supplied to the ignition coil. And a current control circuit 7 that compares the detected current value with a predetermined value and outputs a current limiting signal when the detected current value exceeds the predetermined value. The drive circuit 4 includes an ignition signal. The power transistor 3 is driven in response to the ignition signal from the ignition signal circuit 1 as the generation circuit and the current limiting signal from the current control circuit 7.

In the embodiment described later, the timer means includes a capacitor 611, a comparator 612 that compares the charging voltage of the capacitor 611 with a predetermined value and outputs a timer signal when the charging voltage exceeds the predetermined value, and the comparator 612. Holding circuits 605, 606, and 609 that hold the timer signal of 612, and excess signal generation circuits 607 and 6 that give a signal corresponding to the excess current value to the detected current signal from the current detection circuit 5 according to the timer signal.
13 and charging control circuits 610, 601, and 608 that control the charging and discharging of the capacitor 611 by the feedback signal from the current limiting period detection circuit 8 and the ignition signal from the ignition signal circuit 1. In the embodiment described later, the charging control circuit indicates that the ignition signal from the ignition signal circuit 1 instructs the energization of the primary current, and the feedback signal from the current limit period detection circuit 8 indicates the current limit state. When the feedback signal does not indicate the current limit state or the ignition signal does not indicate the conduction of the primary current, the capacitor circuit 611 is allowed to charge only when Capacitor 611 by either
Is discharged to release the generation of the timer signal from the timer circuit 6.

[Operation and effect of the invention]

 The operation of the above-described configuration of the present invention will be described.

When the energization of the primary current to the ignition coil is started in response to the ignition signal, the primary current value gradually rises and eventually reaches a predetermined value to enter the current limiting state. When the ignition signal disappears, the primary current of the ignition coil is cut off, and
High voltage is output to the next side. In such one-cycle ignition operation, a feedback signal indicating a period in the current limiting state is generated and fed back to the ignition signal generating circuit. Based on this feedback signal, the ignition signal generation circuit can obtain the optimum energization time for the next ignition operation and generate the next ignition signal.

Next, if the ignition signal is kept in a state of instructing energization for some reason such as engine stall, the ignition coil continues to be energized, and the current limiting state is continued. When the duration of the current limiting state continues for a predetermined time or longer, the timer means further reduces the current flowing to the ignition coil from the current limiting state and shuts it off, and continues the generation of the feedback signal. As a result, even if the current supplied to the ignition coil is forcibly cut off without using the ignition signal, it is possible to feed back the fact that the ignition signal is instructing the current supply by the feedback signal.

After that, when the ignition signal disappears to stop energization after returning to a normal state or restarting, the ballast circuit releases the energization cutoff state and stops the generation of the feedback signal, and the ignition signal that follows. Prepare to start energization by.

According to the present invention, since the forced cutoff is performed when the time in the current limiting state exceeds the predetermined time, for example, the starting of the ignition coil is performed at a low temperature when the Batter voltage is low and the cranking rotation speed is low. Since the forced cutoff is performed after the total of the time until the primary current reaches the predetermined value and the predetermined time that defines the duration of the current limit state has elapsed, the forced cutoff is performed before the arrival of the regular ignition timing. It is possible to reduce the number of revolutions performed and to start even at low cranking revolutions.

Moreover, since the feedback signal continues to be generated even when the energizing current to the ignition coil is forcibly cut off, the feedback signal does not reach the peak for the time period that regulates the forcible cutoff, and an abnormal state such as engine stall occurs. It is possible to indicate that there is, and for example, it is possible to set the energization start timing corresponding to the decrease in the rotation speed due to the stop of the ignition operation in the forced cutoff state to the next time.

Further, the timer means is configured not only to start the time measurement in response to the feedback signal but also to respond to the ignition signal and release the energization interruption state by the disappearance of the ignition signal to stop the generation of the feedback signal. Therefore, it is possible to quickly return to the normal operation by returning to the normal state or by cranking for restarting after the engine stall. For example, without turning off the power switch once after an engine stall, it is possible to shift to the restart by just performing the restart operation immediately after the engine stall, and by continuously generating the feedback signal, the power supply start timing suitable for the restart can be set. Excellent restartability can be obtained in combination with the setting.

〔Example〕

The embodiment of the present invention shown in FIG. 1 will be described below.

Reference numeral 1 denotes an ignition signal circuit that outputs a signal for controlling the on / off of the ignition coil 2 in synchronization with the rotation of the engine.
It has a closing angle control function for obtaining the optimum energizing time by feedback control of the current limiting time and outputting it as an ignition signal.

Reference numeral 2 is an ignition coil, 3 is a power transistor for connecting and disconnecting the primary current of the ignition coil 2, 4 is a drive circuit for controlling the power transistor 3 according to an ignition signal from the ignition signal circuit 1, and 5 is a drive circuit for the ignition coil 2. A current detection circuit for detecting the primary current, 6 is a timer circuit, 7 is a current value detected by the current detection circuit 5 and a reference voltage, and the primary current value of the ignition coil 2 is set to a predetermined value determined by the reference voltage. Is a current control circuit for limiting the current. Reference numeral 8 is a current limit period detection circuit for detecting a period during which the primary current of the ignition coil 2 is current limited by the output signal of the current control circuit 7. 9
Is a terminal connected to the positive electrode side of the constant voltage power supply, and 10 is a terminal connected to the positive electrode side of the battery.

The drive circuit 4 has resistors 401 to 404 and transistors 405 to 40
Composed of 7.

The current detection circuit 5 is composed of resistors 501 to 505. The timer circuit 6 is composed of resistors 601-607, transistors 608 and 609, an OR gate 610, a capacitor 611, and a comparator 612.

The current control circuit 7 has resistors 701 to 703 and transistors 704 to 71.
0, diodes 711 and 712, capacitor 713, and current sources 714 to 716.

The current limit period detection circuit 8 is composed of resistors 801-803 and a transistor 804.

 The operation of the embodiment shown in FIG. 1 will be described below.

Waveforms A to H in FIG. 2 represent signal waveforms at points A to H in FIG.

When the ignition signal A (FIG. 2A) from the ignition signal circuit 1 is at a high level, the power transistor 3 is OFF, and when the ignition signal A is at a low level, the power transistor 3 is basically ON.

As shown in the period up to time t1 in FIG. 2, when the ignition signal A is at high level, the transistor of the drive circuit 4
405 and 407 are on, and power transistor 3 is off
In this state, the primary current of the ignition coil 2 does not flow. Further, the output of the OR gate 610 of the timer circuit 6 becomes high level, the transistor 608 is turned on, and the electric charge stored in the capacitor 611 is discharged through the resistor 601.
The capacitor charging voltage E at the point becomes almost 0V.

Next, when the ignition signal A is switched from the high level to the low level at time t1 or time t4 in FIG. 2, the transistors 405 and 407 of the drive circuit 4 are turned off, the power transistor 3 is turned on, and the ignition coil 2 is turned on. Primary current flows. This primary current causes a voltage drop voltage B (FIG. 2B) in the resistor 501 of the current detection circuit 5, and this voltage is detected and output as a detection signal H. This signal H is applied to the base of the transistor 705 of the current control circuit 7, and the current control circuit 7 uses the signal H and the voltage of the terminal 9 connected to the resistors 701 and 702 and an internal constant voltage power supply (not shown). The determined reference voltage (point C in FIG. 1) is compared.

When the primary current value reaches the reference voltage at time t2 or t5 in FIG. 2, in the current control circuit 7, the collector potential of the transistor 706 rises and the emitter potential of the transistor 710 rises. The signal is given to the drive circuit 4 as a signal, and the transistor 406 of the drive circuit 4
Operates in the conducting direction, and the transistor 407 also operates in the conducting direction. The base current of the power transistor 3 is reduced by the operation of the transistor 407 in the conduction direction, and the primary current value of the ignition coil 2 is limited to a predetermined value determined by the current control circuit 7. Thus, in order to limit the energizing current of the primary current of the ignition coil to a predetermined value, a feedback loop regarding the energizing current value is formed.

When this current limitation is started, the current limitation period detection circuit 8
Detects the emitter potential of the transistor 710 of the current control circuit 7 with the transistor 804 via the resistors 801 and 802, and the transistor 804 is turned on. The output signal D of the current limit period detection circuit 8 is fed back to the ignition signal circuit 1 as a feedback signal for a feedback loop relating to the current limit time for making the current limit time an optimum time, and is also input to the timer circuit 6. Has been done. Therefore, the output of the OR gate 610 of the timer circuit 6 becomes low level when the current limiting is started, and the transistor 60
8 turns off. Therefore, the capacitor 611 starts charging via the resistor 602.

When the engine is operating normally, the ignition signal A switches to a high level before the charging voltage of the capacitor 611 reaches the reference voltage (voltage at point F in FIG. 1), as shown at time t3 in FIG. Then, the charging voltage of the capacitor 611 is reset.

However, due to some abnormality such as engine stop (stalling), the ignition signal A may remain at a low level, such as between times t4 and t7 in FIG. In this case, the capacitor 611 is continuously charged through the resistor 602 by the above operation, and when it is charged to the voltage at the point F, the timer output G which is the output of the comparator 612 as shown at time t6 in FIG.
Reverses and switches to high level. This signal is applied to the base of the transistor 705 of the current control circuit 7 via the resistor 607 and the diode 613. Therefore, transistor 7
The base voltage of 05 becomes higher than the reference voltage at the point C, the transistor 710 operates in the conducting direction and the transistors 406 and 407 operate in the conducting direction based on the above-described current limiting operation principle, and the base voltage of the power transistor 3 Decrease
A feedback loop about the current flow turns to reduce the primary current. At this time, the base potential of the transistor 705 does not change while the detected current is large because the high-level output of the comparator 612 is applied. Therefore, the transistors 710, 406, 407 transition by a feedback loop until they are fully conductive. Therefore, all the current flowing through the resistor 403 flows through the transistor 407, the base voltage of the power transistor 3 does not flow, the power transistor 3 is turned off, and the primary current of the ignition coil 2 is cut off.

When the primary current is cut off, the transistor 710 is in the ON state, and the current limit period detection circuit 8
The transistor 804 of No. 2 continues to be in the ON state although the ignition coil 2 is not actually energized. Therefore, the feedback signal D continues to be output even after the primary current is forcibly cut off, and is input to the ignition signal circuit 1 as the current limit time detected by the current limit period detection circuit 8. Then, the ignition signal circuit 1 causes the falling timing of the ignition signal A output next to the time t7 in FIG. 2 so that the current limit time at the time of the next ignition, for example, the restart after the engine stall becomes a predetermined value. The (energization start timing) is feedback-controlled.

It should be noted that time t7 in FIG. 2 shows the time when the internal combustion engine is cranked by a restart operation or the like and the ignition signal A changes again, and when the ignition signal A is input to the OR gate 610, the timer circuit 6 is reset and all signals are returned to the initial state. Since the reset operation is performed by the ignition signal A in this way, after the engine stall, the driver returns the key switch from the IG position to the OFF position and then re-engages it.
It is possible to restart by simply operating from the IG position at the time of engine stall to the starter position immediately after, without operating the position and starter position.

The reference voltage of the timer circuit 6 (voltage at point F in FIG. 1)
By changing or switching depending on the battery voltage, it is possible to have a characteristic depending on the battery voltage in the time from the start of current limitation to the interruption.

Further, the resistor 602 can be replaced with a current source, and the charging characteristic of the capacitor 611 may be changed according to the battery voltage.

[Brief description of drawings]

FIG. 1 is an electric circuit diagram showing an embodiment of the device of the present invention.
The drawings are waveform charts of respective parts provided for explaining the operation of the apparatus shown in FIG. 1 …… Ignition signal circuit, 2 …… Ignition coil, 3 …… Power transistor, 4 …… Drive circuit, 5 …… Current detection circuit, 6 ……
Timer circuit, 7 ... Current control circuit, 8 ... Current limit period detection circuit.

Claims (2)

(57) [Claims] 1. An ignition device for an internal combustion engine, which is combined with an ignition signal generating circuit (1) for generating an ignition signal indicating an energization period by obtaining an optimum energization time of an ignition coil. Control means (3, 4, 5, 7) for intermittently energizing the ignition coil in response to an ignition signal and limiting an energizing current to the ignition coil to a predetermined value, and the ignition coil by the control means. Feedback signal generating means (8) for detecting that the energizing current is limited to a predetermined value, generating a feedback signal indicating the duration of the current limiting state, and feeding the feedback signal back to the ignition signal generating circuit; Timer means configured to initiate a time measurement in response to a feedback signal and reset the time measurement in response to the ignition signal. Together with the current limit blocks the energizing current to further reduce the current limit by the control means energizing current to the ignition coil and is determined that continues for a predetermined time or longer,
Even in this energization cutoff state, the generation of the feedback signal to the ignition signal generation circuit is continued, and the energization cutoff state is released in response to the disappearance of the ignition signal,
Timer means (6) for stopping the feedback signal
An ignition device for an internal combustion engine, comprising: 2. The control means detects a current flowing to the ignition coil and outputs a detection current signal to a detection circuit (5), and compares the detection current value by the detection circuit with a predetermined value to detect the current. A current control means (7) for outputting an energization limiting signal when the current value exceeds a predetermined value, wherein the feedback signal generating means outputs the feedback signal in response to the energization limiting signal of the current control means, When it is determined that the detected current value output by the timer means and input to the current control means is an excessive current value and the feedback signal has continued for a predetermined time or more, the energization limit signal is continuously output. The ignition device for an internal combustion engine according to claim 1, wherein the ignition device is an internal combustion engine.