JPS58197470A - Ignition timing controller - Google Patents

Abstract

PURPOSE:To make the optimum ignition timing controllable at every cylinder, by finding a crank angle in time of the maximum of pressure at each cylinder, while controlling the ignition timing at every cylinder so as to cause the given value to become the same as all cylinders equally. CONSTITUTION:Pressure sensors 1-4 are installed at every cylinder each, and each sensor outputs each of pressure signals S1-S4 corresponding to pressure inside a combustion chamber. These pressure sensors 1-4 use a piezoelectric element that is installed in the position of a washer of an ignition plug. The output value of each of pressure sensors 1-4 is converted into a binary code by an AD converter 10 via a multiplexer 9. This binary code is inputted into an operation device 7. At this operation device 7, a crank angle in time of the maximum of pressure at each cylinder is found. Furthermore, the ignition timing at each cylinder is calculated in a direction capable of compensating differences among cylinders. With this, ignition is well performed in optimum conditions at all cylinders all the time.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ignition timing control device for a spark-ignition internal combustion engine.

As a conventional ignition timing control device, 9 methods detect the pressure in the combustion chamber of an engine and control the ignition timing so that the pressure reaches a predetermined value at a position where the pressure reaches its maximum value. There is a method such as No. 56429 of 1953.

There are some differences depending on the engine, but the pressure inside the combustion chamber.

When the ignition timing is set so that the position where the force is at its maximum value is at the crank angle ATDC←1 dead center - 20° (after L dead center), the torque generated by the engine becomes maximum.

Furthermore, as shown in Fig. 1, the position θ□ where the combustion chamber pressure reaches the maximum value Pm is a position slightly delayed from TDC (top dead center), but by changing the ignition timing θ0,
can be moved (the faster θ0, the faster the brocade).

Therefore, the ignition timing is controlled 1 as in the method described in -1-, and the position where the combustion chamber pressure reaches its maximum value is ATDC 10°~
If it is set at the 20° position, the torque generated by the two engines can be controlled to be maximized.

However, in the conventional device as described above, all cylinders are uniformly controlled using the average value of all cylinders, so taking into account variations in size and temperature between cylinders, it is not always possible to reach the optimal ignition timing. It wasn't.

The present invention has been made to solve the above problems, and an object of the present invention is to provide an ignition timing control device that can control the ignition timing to the optimum ignition timing for each cylinder.

- In order to achieve the objects set forth in the present invention.

The combustion chamber pressure is detected for each cylinder, the crank angle at maximum pressure is determined for each cylinder, and the ignition timing is controlled for each cylinder so that the value is the same for all cylinders.

The present invention will be described in detail below based on the drawings.

FIG. 2 is a diagram showing an embodiment of the present invention, and shows the case of a 4-stroke, 4-cylinder engine.

In FIG. 2, pressure sensors 1 to 4 are provided for each cylinder, and output pressure signals 81 to S4 corresponding to the combustion chamber pressure. Note that 1 to 4 correspond to the first to fourth cylinders, respectively. As the pressure sensors 1 to 4, for example, pressure sensors 9 are used in which a piezoelectric element is installed at the position of a washer of a spark plug.

,,4' Next, the crank angle sensor 5 detects that the crankshaft is 21! ! Every time one rotation (720°) is made, a reference pulse S5 is output at a predetermined position 9, for example, compression I-dead center (TDC) of the first cylinder.

Also, for every unit angle of the crankshaft, for example, 1°, a unit pulse S
Outputs 6.

Next, the control device 6 controls the arithmetic device 7. Memory 8. Multiplexer9. AD converter 10. Register 11. counter 12
and a comparator 13. In addition.

This control device 6 can be constituted by 9, for example, a microcomputer, in which case 7 is a CPU.

8 corresponds to RAM and ROM, and 11 to 13 correspond to input/output interfaces.

Next, the ignition device 14 is connected to the power source 151, the ignition coil 16. Transstar 17. It is composed of a dust diffuser 18 and spark plugs 20A to 20D. and control device 6
A high voltage is generated in the ignition coil 16 at the time when the ignition signal S7 is applied (when S7 falls).

At that time, the spark plug (one of 20A to 20D) selected by the dust distributor 18 is configured to generate spark discharge and ignite.

The operation of the control device 6 will be explained below.

The control device 6 performs calculations as shown in the flowcharts of FIGS. 3 and 4. What is the firing order?

1st. Third. 4th. This is the second cylinder.

First, the calculation shown in FIG. 3 will be explained.

The arithmetic unit 7 inputs the reference pulse S5 and the unit pulse b6, and controls an internal counter (not shown) as follows. That is, when the reference pulse S5 is manually applied, the counter is reset, and thereafter the counter is counted up by five human-powered pulses S6.

When the count number is 0 to 60, that is, when the compression stroke of the first cylinder is ATDCO° to ATDC60',
The multiplexer 9 is controlled to output one signal Sl for the first cylinder.
input, convert it into a digital signal with the AD converter 10, and calculate the crank angle (count number) when the value reaches the maximum value (the largest value in - explosion strokes) when the count number is 60. At this time, the data is stored at a predetermined location in the memory 8 (calculations P1 to P6 in FIG. 3).

That is, r　P2 converts S into a digital signal.

Next, at P3, the value of 81 (digital value) at that time is compared with MAX (previous Sabato value of 81) stored in the memory 8.

If YES in P3, that is S, > MAX, go to P4, store the value of 81 at that time as the new MAX in memory 8, and set the crank angle at that time to AM.
After memorizing it as AX, go to P5.

If the answer is No at P3, go to P5 immediately. Therefore, S,
Find the maximum value of and the crank angle at that time.

Next, in P5, it is determined whether or not the angle is 60°, and if it is 60°, the process goes to P6.

At P6, the crank angle AMA when SI reaches its maximum value
Transfer X to memory 8 and use MA for the second calculation.
Set X to 0.

In the same way, the count number is 180 to 240 (3rd cylinder A
TDCO°~60°), the third cylinder pressure signal s3
.

360 to 420 (4th cylinder ATDCO° to 60°), the 4th cylinder pressure signal is 84,540 to 600 (2nd cylinder ATDCO° to 60°).
When the cylinder ATDCO° to 60°), the pressure signal S2 of the second cylinder is AD converted, and the crank angle when each value reaches the maximum value is stored in a predetermined location in the memory 8.

The crank angles listed below are converted into values from 1] dead center of each cylinder and stored. Therefore, the maximum count number for the 3rd cylinder is A3-180, and for the 4th cylinder, it is A4-, '4fi.
rl.

In the second cylinder, A2-540 is calculated and stored.

That is, the stored value 1- is a value corresponding to the compression stroke for each cylinder (-the time when the pressure reaches the maximum from the dead center is expressed as the maximum pressure angle below the crank angle of A).

Moreover, the value of the maximum pressure hour angle in 1- is stored as the result of the past four calculations for each trough cylinder, and is sequentially updated each time a new result is received.

Therefore, in the case of 4 cylinders, 4X4=+6 values are always stored.

Next, the calculation shown in FIG. 4 will be explained.

In the calculation shown in FIG. 4, the count number of a counter (not shown) in the calculation device 7 described in 01f is 110. 290. 47
This is done by issuing an interrupt every time 0 or 650 is reached.

The four counts shown in -1- each indicate the position of the compression stroke 1 of each cylinder - 70 degrees before dead center (BTDC 70 degrees).

In FIG. 4, first, P7 calculates the ignition timing using the normal procedure.

This calculation is performed, for example, as follows.

First, engine rotational speed information (obtained by measuring the number of unit pulses s6 input within a predetermined time), intake air amount information, melo/torre opening information, etc., which are not shown in FIG. 2, are input.

Next, it is determined whether or not it is idle (when the throttle/7 torque valve is fully closed), and when it is idle, the ignition is pre-stored in the memory 8 as a value corresponding to 9 rotation speeds as shown in Figure 5 (A). Search for period D (indicated by the lead angle value of TDC). Also when not idle.

As shown in FIG. 5(B), the ignition timing is retrieved, which has been previously stored in the memory 8 as a value corresponding to the rotational speed and intake air amount.

Next ij, Ps ”C・Imaichi calculation is 110° (3rd cylinder o
-F-death Mif 70°),
If YES, go to P9.

In P9, the four values of the maximum pressure hour angle of the third cylinder stored in the memory 8 are read out, and the average value θ37 is read out.
0. is calculated, and a correction amount d3 based on the following formula is calculated.

When θ31,1≧20, da −= ds +220
> θ3 +++ > 15, d3=dh+1θ3m=I
When 5, da = d5 When 15〉03m>10, d3=d5-110≧θ3
．． When n, d3=d5-2'' As described in 1, when the average value θ3m is 15, that is, when the pressure in the combustion chamber reaches its maximum value, the angle of cracking is ATDCI 5° (15° of the explosion stroke). At this time, the correction amount d3 is kept as the reference correction amount d1, and when θ31□ is larger or smaller than 15, the correction amount is increased or decreased accordingly.

Note that the value of the reference correction amount d5 is 1, for example, 0.

Further, when the correction amount d3 is d3=2, it means that the ignition timing is advanced by 2 degrees from the ignition timing calculated in P7, and when it is da--2, it means that the ignition timing is retarded by 2 degrees from I).

Next, the PIO calculates 7O-(D+d3) and transfers the value to the register 11 in FIG.

For other cylinders, the average value θ for the cylinders that undergo the secondary ignition stroke is similar to the above. Calculate m (n is 1 to 4),
Based on this, 7O-(D+dn) is calculated and transferred to register H.

Therefore, register 1 stores the value 7O-(D+dn) for the cylinder that will undergo the ninth ignition stroke.

Next, the creation of the ignition signal S7 will be explained.

In FIG. 2, register H stores the value 70 (D+dn) for the cylinder that will undergo the next ignition stroke as described above.

The arithmetic unit outputs the reset signal S8 at the same time as the interrupt timing shown in FIG. 4, that is, at 110°, 290°, 470", and 650°.

The counter 12 is reset by a reset signal S8, and then counts up the unit pulse S6 which is manually input.

The comparator 13 compares the value of the counter 12 and the value of the register 11, and outputs an ignition signal S7 that falls when the two match.

The above signal waveform is shown in FIG.

As can be seen from FIG. 6, at a point T (1) advanced by p+d3 from 180° (compression stroke of the third cylinder - dead center), the ignition signal S7 falls and two ignitions are performed.

As shown in Fig. 7 (broken line A is ignition timing, solid line B is torque), if the ignition timing is advanced by two (increasing the value of D+d), the crank/glide angle at maximum pressure, that is, the above-mentioned maximum pressure The angle becomes smaller.

Therefore, as in the present invention, the ignition timing should be controlled for each cylinder so that the average value of the maximum pressure hour angle for each cylinder is set to a predetermined value (for example, ATDC+5'').

Regardless of variations between cylinders or changes over time, it is possible to maximize the generated torque even in the same cylinder.

As described below, the present invention is configured to detect the combustion state of each cylinder and provide each cylinder with the ignition timing that maximizes the generated torque. It is possible to always perform optimal ignition in all cylinders, regardless of aging.

This has the effect of improving fuel efficiency.

[Brief explanation of drawings]

Fig. 1 is a combustion chamber pressure characteristic diagram, Fig. 2 is an embodiment of the present invention, Figs. 3 and 4 are an embodiment of a flowchart showing calculations of the present invention, and Fig. 5 is an ignition timing characteristic diagram. 6 is a signal waveform diagram of the device shown in FIG. 2, and FIG. 7 is a diagram showing the relationship between generated torque, ignition timing, and crank angle at maximum pressure. Explanation of symbols 1 to 4...Pressure sensor 5...Crank angle sensor 6...
...Control device 7...Arithmetic device 8 -Memory
9...Multiplexer 10...AD converter
11 Register 12 Counter 13・
・Comparator 14・Ignition device 15...Power supply 16・
・1 ignition coil 17...transistor 18...
Distributor 20A-20D/Spark Plug Attorney Junnosuke Nakamura

Claims (1)

[Claims] In a multi-cylinder internal combustion engine, means for transmitting a signal corresponding to the combustion chamber pressure of each cylinder, and calculating and storing a crank angle at which the pressure of the explosion stroke of each cylinder is maximized based on the signal, - An ignition timing control/device comprising means for calculating ignition timing for each cylinder so that the crank angle at the maximum pressure is the same for all cylinders.