JPS6361775A - Ignition control device for internal combustion engine - Google Patents

Abstract

PURPOSE:To enable prevention of heat generation of an ignition coil even during the occurrence of an engine stop, by a method wherein, after a given time responding to an engine state lapses commencing in the starting of a primary coil, a primary current is disconnected even if it is not an ignition timing. CONSTITUTION:An engine control device 10 inputs engine running information from a rotation angle sensor 1, a load sensor 2, a water temperature sensor 3, and a battery voltage sensor 4 to a CPU 14. It computes and ignition timing and an energizing time optimum to engine running conditions, and outputs a computing ignition signal to a hard soft switching circuit 13. In which case, since a value being K-times as high as a preceding energizing time is set in the output comparing resistor of the CPU 14, even if no signal from the rotation angle sensor 1 is inputted, when an energizing time being K-times or more lapses commencing in energization of a primary current, an ignition coil 20 is brought into a non-energizing state, and the high current lock state of a power transistor 15 is rendered ineffective. This constitution enables the ignition coil 20 to be prevented from heat generation even during the occurrence of an engine stop.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to an ignition control device for an internal combustion engine.

[Conventional technology]

Conventionally, in order to prevent heat generation in the ignition coil due to no energization of the primary current in the ignition coil when the engine stalls, a system has been devised that cuts off the energization of the primary current after a certain period of time has elapsed after starting the energization of the primary current. (For example, Japanese Patent Laid-Open No. 58-211561).

[Problem that the invention seeks to solve]

However, in the conventional system described above, the primary current is cut off after a certain period of time after energization starts, so this certain period of time must be set to the longest time that corresponds to the worst conditions of the internal combustion engine. Therefore, there was a problem in that it was not possible to sufficiently prevent the ignition coil from generating heat when the engine stalled.

Therefore, the present invention is designed to effectively prevent the ignition coil from generating heat even when the engine is stalled depending on the engine condition.

[Failure to solve the problem]

Therefore, as shown in FIG. 1, the present invention includes an engine state detection means for detecting the operating state of an internal combustion engine, and an ignition timing and energization time for calculating ignition timing and energization time according to the engine state detected by the engine state detection means. time calculation means; ignition coil intermittent means for intermittent primary current of the ignition coil according to the calculated ignition timing and energization time; energization time K multiplication means for multiplying the calculated energization time by; The present invention provides an ignition control device for an internal combustion engine, which includes an energization cutoff means that cuts off the primary current when a current supply time equal to or longer than the above-described current supply time has elapsed since the start of current supply.

[Effect]

Thereby, the primary current of the ignition coil is intermittent by the ignition coil intermittent means according to the ignition timing and energization time calculated by the ignition timing and energization time calculation means according to the engine state. Then, the calculated energization time is multiplied by the energization time K multiplication means, and when the energization time multiplied by the time has elapsed since the start of energization of the primary current, the energization cutoff means cuts off the primary current.

〔Example〕

The present invention will be described below with reference to embodiments shown in the drawings.

FIG. 2 shows the system configuration of the first embodiment of the present invention. 1
is a rotation angle sensor that is attached to an internal combustion engine (not shown) and detects the rotation angle of the engine (for example, it outputs one pulse signal for each cylinder, but it also outputs multiple pulses such as a reference position signal and an angle signal) (a signal sensor may also be used), 2 is a load sensor that detects the engine load, 3 is a load sensor that detects the engine load.
4 is a water temperature sensor that detects the engine cooling water temperature, and 4 is a battery voltage sensor. These signals are taken into an engine control unit (ECU) 10.

The signal of the rotation angle sensor 1 is input to the waveform shaping circuit 11, the output thereof is input to the hardware/software switching circuit 13 and the CPU 14 constituting the microcomputer, and the output of the hardware/software switching circuit 13 drives the power transistor 15. Then, the primary current of the ignition coil 20 is applied. Furthermore, by cutting off the current to the ignition coil 20 at the ignition timing, a high voltage for ignition is generated at the optimum timing. Signals from the load sensor 2, water temperature sensor 3, and battery voltage sensor 4 are input to the A/D converter 12 and A/D converted, and the A/D converted signals are taken into the CPU 14. The calculation output (calculated ignition signal, hardware/software switching signal) from the CPU 14 is output to the hardware/software switching circuit 13 . In the hardware/software switching circuit 13, CPU1
With the switching signal from 4, the rotation angle signal (fixed ignition signal) generated at a fixed angle position of the internal combustion engine can be used as it is as the ignition signal (signal for driving the power transistor 15), or the calculated ignition signal from the CPU 14 can be used. It is configured to switch whether to use it as an ignition signal or not.

Next, the operation of the above configuration will be explained.

The engine control device IO takes in engine operating information from a rotation angle sensor 1, a load sensor 2, a water temperature sensor 3, a battery voltage sensor 4, etc. through a waveform shaping circuit 1.1, an A/D converter 12, etc., with a CPU 14, It calculates the optimum ignition timing for the engine operating conditions, and outputs a calculated ignition signal to the hard/soft switching circuit I3. In addition, when the engine speed is low, the engine speed fluctuation becomes large, so hard ignition control is used (the rotation angle signal is used as the ignition signal), but the switching signal is also controlled by the CPU.
4 to the hard/soft switching circuit 13, and is set to hard ignition control using a fixed ignition signal.

Based on the output signal from the hard/soft switching circuit 13, the power transistor 15 energizes the primary current of the ignition coil 20. Also, by cutting off the current to the ignition coil 20 at the ignition timing, a high voltage for ignition is generated at the optimum timing.

FIGS. 3 and 4 show program flowcharts of the main parts of the CPU 14. The routine 200 in Fig. 3 operates on one side of the edge of the rotation angle sensor signal [the edge that occurs near the top dead center of each cylinder (Fig. 5 (the position of all middle-colored squares))]. There is.

First, in step 201, the current time of occurrence is saved. In the next step 202, the energization start or ignition timing calculated by the CPU 14 is set in the output comparison register (OCR) in the CPU 14, and this routine is exited.

Internal interrupt processing (OCi processing) 300 shown in FIG. 4 is started when the time difference between the set value of the output comparison register (OCR) and the current time timer becomes zero. Step 30
1 saves the current occurrence time. Next step 3
In step 02, it is determined whether or not the energization has started, and if the energization has not started, the process advances to step 305 and ends the current interrupt process.

If energization is to start, the process advances to step 303 and the previous energization time T is determined. Set the value multiplied by N as TRC.

This energization time TON is determined from the rotation speed, battery voltage, etc.
OCR the TRC from the required energization start to ignition timing
is set, the process proceeds to step 305, and the current interrupt processing is ended.

Next, the operation will be explained using the time chart of FIG.

Conventionally, as shown in Fig. 5 fb), each edge ■, ■
In order to output the ignition signal from
(Time required to start energizing from Edge ■), DC2 (
Since it is controlled based on the time corresponding to the ignition timing from the edge (), if a large rotation drop or engine stall occurs, the ignition signal becomes energized and the power transistor remains conductive.

However, in this embodiment, normally, a down count value is sent to the OCR at each edge of the rotation angle sensor signal, that is, the DCI is set to the OCR at the edge . ), that is, at the timing when the ignition signal is turned on, the OCR is informed of the previous energization time T.
Set the value (TRC) multiplied by oN. This TRC
When the edge of ■ in Figure 5(a) comes during the down count, by resetting DC2 to 0CR, DC2
After a period of time equivalent to , ignition occurs.

Even if the engine stalls and the signal from the rotation angle sensor l is not input, the value obtained by multiplying the previous energization time T.N by (TRC) is set in ocR at the timing shown by ■ in Fig. After the TRC time, the ignition coil 20 becomes de-energized and the power transistor 15 is no longer locked in the large current state.

Another embodiment of the present invention will be described according to FIG.

In the embodiment described above, the previous energization time T is used to determine the TRC0 value. Although the value multiplied by N is a constant value, this value may be a function of the rotational speed NE (K=NEXK'K (for example, 1/200)).

Alternatively, the value may be changed stepwise depending on the rotational speed as shown in FIG.

〔Effect of the invention〕

As described above, in the present invention, the primary current is cut off even when the ignition timing is not reached after a predetermined period of time according to the engine condition has elapsed after the start of energization of the secondary coil, so that the ignition can be started even when the engine is stalled depending on the engine condition. This has the excellent effect of effectively preventing heat generation in the coil.

[Brief explanation of the drawing]

FIG. 1 is a diagram corresponding to the claims of the present invention, FIG. 2 is a block diagram showing a first embodiment of the present invention, and FIGS. 3 and 4 are for explaining the operation of the CPU in the device shown in FIG. FIG. 5 is a time chart for explaining the operation of the device shown in FIG. 2, and FIGS. 6 and 7 are engine speed-value characteristic diagrams in other embodiments of the device of the present invention. 1 to 4...Rotation angle sensor, load sensor, water temperature sensor, battery voltage sensor constituting engine state detection means, 14
... CPU, 15 ... Power transistor forming ignition coil intermittent means, 20 ... Ignition coil.

Claims (3)

[Claims] (1) Engine condition detection means for detecting the operating condition of the internal combustion engine; ignition timing/energization time calculation means for calculating the ignition timing and energization time according to the engine condition detected by the engine condition detection means; ignition coil intermittent means for intermittent primary current of the ignition coil according to the ignition timing and energization time; and an energization time K that multiplies the calculated energization time by K.
An ignition control device for an internal combustion engine, comprising a doubling means and an energization cutoff means for cutting off the primary current when the energization time multiplied by the K times or more has elapsed since the start of energization of the primary current. (2) The ignition control device for an internal combustion engine according to claim 1, wherein the value multiplied by K changes depending on the engine speed. (3) The ignition control device for an internal combustion engine according to claim 1, wherein the energization time is calculated according to the battery voltage.