JPS6056267B2 - engine ignition system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an engine ignition device that controls the closing rate of an output transistor that intermittents power supply to an ignition coil to an optimum value, and in particular, relates to an engine ignition system that controls the closing rate of an output transistor that intermittents power supply to an ignition coil to an optimum value. The time is measured, and this measured time is used as the basic data for the calculation of the ignition coil.
Therefore, it is an object of the present invention to provide an engine ignition system that can control the optimum closed circuit ratio with extremely high accuracy without being affected by power supply voltage fluctuations, the type of ignition coil, etc.

Embodiments of the invention shown in the figures will be described below.

That is, in FIG. 1, 1 is a reference signal generator that detects the reference rotation angle position of the engine's crankshaft (for example, each top dead center position of a multi-cylinder engine) and generates a reference signal. A magnetic modulation section (protrusion or notch) is provided on a rotating body driven by a rotor, and a magnetic pickup is fixedly provided opposite to the magnetic modulation section. 2 is an ignition timing control unit that generates an ignition timing signal by calculating the ignition timing with advance characteristic according to engine speed and intake negative pressure based on the reference signal; 3 generates a clock signal of a predetermined frequency; an oscillator; 4 is an n-bit counter that counts the clock signal within the period of the ignition timing signal to count the period corresponding to the number of rotations; 5 is an n-bit counter that calculates the rotation period measured by the counter to the ignition timing signal This is a register that temporarily stores data in synchronization.

6 is an ignition coil supplied with power from a DC power source (not shown); 7
8 is an output transistor connected in series to the ignition coil; 8 is a resistor for detecting the primary current of the ignition coil 6; 9 is a resistor for detecting the primary current of the ignition coil 6;
10 is a level detector that generates a timing signal when the voltage value of this resistor reaches a predetermined value; 10 is a differentiation circuit that differentiates the 0N, 0FF drive signal of the output transistor 7 and generates a reset signal at the 0N timing; 11 12 is a counter that counts the clock signal from the oscillator in synchronization with the reset signal from the differentiating circuit; 12 is a register that temporarily stores the value of the counter 11 when the output from the level detector 9 is generated; 13 is a register 14 is the register 5 which adds the high-order specific bit output of the output (n-bit binary value) of the register 5 to the output of the register 5.
A subtracter 15 subtracts the output of the adder 13 from the output of the ignition timing signal, and the output of the subtracter 14 is preset by the ignition timing signal, and the count signal is subtracted from the preset value until the counted value becomes zero. The preset counter 16 which generates an output when the preset counter 15 reaches the preset counter 15 is a flip-flop which generates a signal which is reset by the output of the preset counter 15 and the ignition timing signal to drive the output transistor 7 from 0N to 0FF.

Next, the operation of the device configured as described above will be explained.

The signal generator 1 generates a reference signal for each reference angle according to the rotation of the engine, and the ignition timing control unit 2 uses this reference signal as a reference to adjust the ignition timing with advance characteristics according to the engine rotation speed and intake negative pressure. is calculated to generate an ignition timing signal. The counter 4 is reset by this ignition timing signal, and at the same time measures the ignition timing signal period by sequentially counting the clock signal from the oscillator 3. In synchronization with the ignition timing signal, the counter 4 stores the ignition timing period in the register 5. The output (n-bit binary value) TO of the corresponding counter 4 is stored. On the other hand, the counter 11 is reset by the output of the differentiating circuit 10 (generated at the ON timing) for differentiating the ON/OFF drive signal of the output transistor 7, and at the same time sequentially counts the clock signal of the oscillator 3. When the voltage drop across the resistor 8, which is proportional to the primary current value of the ignition coil 6 energized by ON of the transistor 7, reaches a predetermined value, the level detector 9 stores the count value of the counter 11 at this point in the register 12; That is, the output corresponding to the energization time required for the primary current to reach the specified value is stored. The n-bit binary output T1 stored in this register 12 is generated by the adder 13 by shifting the output of the upper specific bit number of the rotation period output (n-bit binary output) stored in the register 5. will be added. Therefore, this addition output TON is obtained by adding the output T2, which is several percent (constant ratio) of the output of the register 5, to the register T1 (T1+
T2). The subtracter 14 receives the rotation period output T stored in the register 5. The energization time output TON of the adder 13 is subtracted from (TO-TON) to generate an output (TOpp) corresponding to the cut-off time of the ignition coil 6. This cutoff (0FF) time output (TOFF) is preset in the preset counter 15 every time the above-mentioned ignition timing signal occurs, and the clock signal of the oscillator 3 is subtracted from the preset value and counted, and becomes 0N at the time when the counted value reaches zero. A timing signal is generated. The flip-flop 16 is set and reset by the 0N timing signal and the ignition timing signal of the preset counter 15, and generates 0N and 0FF drive signals for the transistor 7, thereby determining the closing rate of the transistor 7. Therefore, during the ON period of the transistor 7, the energization time required for the primary current to reach the specified value within the ignition cycle is detected and stored, and the energization time T is determined from the ignition cycle TO.

Time T subtracted by N. It is determined by setting FF as the primary current cutoff time in the next ignition cycle,
The ON time of the output transistor 7 can be controlled to the time required for the primary current to substantially reach the specified value, and the circuit is closed to the optimum value regardless of variations in the primary current rise characteristics of the ignition coil 6 and fluctuations in the power supply voltage. There are things you can do to control the rate. Note that the adder 13 corrects the time output required for the primary current to reach the specified value in accordance with the rotation period, but this is because the ignition period fluctuates at low speeds such as when starting the engine, and the primary current In order to ensure the minimum necessary current application time even when the current application time fluctuates unstably in each ignition cycle, control is performed to give a longer current application time at lower speeds. In the above embodiment, the rotation period is measured by measuring the period of the ignition timing signal obtained by controlling the timing of the reference signal, but the same effect can be obtained by measuring the period of the reference signal. In this case, the counter 4 and register 5 may be configured to be triggered by the reference signal.

As described above, according to the present invention, the time required for the primary current of the ignition coil to reach a specified value is measured, and the time required for the primary current of the ignition coil to reach a specified value is subtracted from the specified rotation period. By setting the 0N timing of the output transistor to the time when Regardless of differences in the primary current rise characteristics due to variations or fluctuations in the power supply voltage, the circuit can always be controlled to the optimum closing time, making it possible to control the closing rate with extremely high accuracy.

In addition, the open circuit time of the output transistor subtracted from the rotation period is determined by calculating the upper specific bit output of the rotation period count value with respect to the count output value that measures the time required for the primary current of the ignition coil to reach a specified value. Since it is determined by digit matching and addition, it is possible to provide a closing time that is a composite of a predetermined ratio time of the rotation period with a simple configuration, and even when the engine rotation is unstable at low speed. A simple configuration can reliably secure the energization time of the ignition coil.

[Brief explanation of drawings]

The figure is a block circuit diagram showing one embodiment of the present invention.

Claims (1)

[Claims] 1. An output transistor connected in series to the power supply circuit of the ignition coil, a primary current detection means for detecting that the primary current of the ignition coil has reached a specified value, and 1 of the ignition coil.
energization time counting means for measuring and storing the time from the start of energization of the next current to the time when the output of the primary current detection means is generated by counting clock signals; Rotation period counting means for measuring and storing by counting signals; addition means for digit-aligning and adding the high-order specific bit output of the output of the rotation period counting means to the output of the energization time counting means; and the rotation period counting means. subtracting means for subtracting the output of the adding means from the output of the means; and timer means for determining the closing timing of the output transistor after a time corresponding to the output of the subtracting means has elapsed from the timing determined based on the ignition timing signal. Equipped with an engine ignition system.