JPS5843584B2 - Ignition timing control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ignition timing control device for an internal combustion engine, and more particularly to an ignition timing control device that improves drivability and stability during sudden changes in operating conditions.

Recently, electronic ignition timing control devices have been developed that use arithmetic devices such as microcomputers to calculate ignition timing (advanced or retarded) based on engine operating variables such as engine speed and load. .

The above-mentioned electronic ignition timing control device can widen the control range of the ignition timing compared to conventional mechanical advance devices such as centrifugal advance devices and vacuum advance devices. It is characterized by the ability to easily set the most suitable ignition timing.

However, in the electronic ignition timing control device, the ignition timing is calculated based on the engine operating state, so when the operating state changes, the ignition timing may suddenly change discontinuously.

In particular, there is a method that divides operating conditions into several types, has a table that stores the ignition timing for each type, and reads out the ignition timing from those tables according to the operating condition. Set the ignition timing according to the cooling water temperature, (2) set the ignition timing according to the rotation speed when the idle switch is on, (3)
) During normal operation, the ignition timing is set by reading values stored in a table corresponding to the rotation speed and load (detected from suction negative pressure, intake air flow rate, or injection pulse width). When the states of (2) and (3) change, the corresponding table also changes, so there is a risk that the ignition timing may suddenly change discontinuously.

If the ignition timing suddenly changes, the torque generated by the engine will change suddenly, resulting in poor drivability, and the dwell angle will become unstable, causing the ignition coil to be energized for too long or too short. The power transistor is damaged or
If it is too short, ignition energy will be insufficient, and in severe cases, there is a risk of misfire or backfire.

The present invention has been made in view of the above problem, and it stores the ignition timing used in the previous ignition (hereinafter simply referred to as the previous time), compares it with the current calculated value, and calculates the difference. If the difference is outside the limit range that varies according to predetermined operating variables, the ignition timing is set to a value that is limited so that the difference is within the limit range, thereby preventing sudden changes in the ignition timing and improving stability. An object of the present invention is to provide an ignition timing control device that improves the drivability and stability of an engine by changing the ignition timing as quickly as possible without impairing the ignition timing.

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

FIG. 5 is a diagram showing the overall configuration of the present invention.

In FIG. 5, numeral 30 is a sensor group for detecting various operating variables of the engine, such as rotational speed and load, and corresponds to, for example, 7 to 12 in FIG. 1, which will be described later.

Reference numeral 31 denotes calculation means for calculating the ignition timing suitable for the operating condition of the engine in accordance with the outputs of the above-mentioned sensor group.

Note that the calculation means 31 calculates the ignition timing in synchronization with the engine rotation or periodically at fixed time intervals.

Further, 32 is a detection means for detecting at least one operating variable among rotational speed, load, engine temperature, and battery voltage.

Note that this detection means 32 can be omitted by sharing the output of the sensor group 30 when the operating variable to be detected is common to the sensor group 30.

Reference numeral 33 denotes a limit range calculation means for calculating a limit range according to the operating variables detected by the detection means 32.

The above limit range defines the allowable range for the difference between the previous ignition timing and the current ignition timing, with the upper limit being the limit when the current ignition timing is advanced compared to the previous time, and the lower limit being the limit when the current ignition timing is retarded. .

Furthermore, the storage means 34 stores and outputs the ignition timing used during the previous ignition.

Further, the difference calculation means 35 calculates the difference between the previous ignition timing given from the storage means 34 and the current ignition timing calculated by the calculation means 31.

Next, the limiting means 36 determines that the difference calculated by the difference calculating means 35 is
If it is within the limit range calculated by the limit range calculation means 33, the current calculated value is output as is as the ignition timing, and if the above difference is greater than the upper limit of the limit range (more than the limit on the advance side), the difference is the upper limit. If the difference is below the lower limit (more than the limit on the retard side), a value obtained by limiting the current calculated value so that the difference becomes the lower limit is output as the ignition timing.

Next, the control means 37 outputs an ignition signal when the ignition timing given by the restriction means 36 is reached, whereby the ignition device 38 (corresponding to 13 to 20 in FIG. 1 described later) is operated to perform ignition. It will be done.

In FIG. 5, portions 30, 31, 37, and 38 are the same as those of the conventional device, and portions 32 to 36 are characteristic portions of the present invention.

Next, the present invention will be explained based on examples.

FIG. 1 is a block diagram of one embodiment of the present invention.

In FIG. 1, numeral 1 denotes an arithmetic unit, which is composed of, for example, a microcomputer.

Further, 7 is a rotation sensor that outputs a signal s8 corresponding to the engine rotation speed, 8 is a negative pressure sensor that outputs a signal S2 that corresponds to the engine suction negative pressure, and 9 is a signal S that corresponds to the engine cooling water temperature.
10 is an idle switch that detects the idling state of the engine and outputs an idle signal S4.

Reference numeral 11 is a reference angle sensor that outputs a reference angle pulse S for each reference angle of the crank angle (for example, 120'), and 12 is a unit angle sensor that outputs a unit angle pulse S6 for each unit angle of the crank angle (for example, 1°). It is a sensor.

In the arithmetic section 1, the arithmetic device 2 includes each of the above-mentioned sensors 7 to
Each of the 10 signals (in addition to these, an injection pulse signal, a transmission shift position signal, a vehicle speed signal, etc. may be used as necessary) is input, and the ignition timing corresponding to the engine operating state is calculated by calculation. Alternatively, tables 3 to 5 store ignition timing in advance and are divided according to the type of each operating state (for example, table 3 is a temperature table, table 4 is a rotation speed table, and table 5 is a table corresponding to rotation speed and load). The basic value of the ignition timing is set by reading out the value corresponding to the operating state at that time from the table).

Next, the ignition timing used in the previous ignition stored in the memory 6 is compared with the current basic value, and if the difference between the previous value and the current basic value is within the specified limit range. For example, the above basic value is used as the current ignition timing, and if the above difference is outside the limited range, a value limited to the limited range is determined as the current ignition timing.

Then, from the time when the reference angle pulse S5 is given from the reference angle sensor 11, the ignition signal S7 is outputted at the time when the unit angle pulse S6 of the unit angle sensor 12 is given as many as the number corresponding to the determined ignition timing. .

This ignition signal S7 interrupts the primary circuit of the ignition coil 13, and sends the generated high voltage current to the spark plugs 15 to 20 via the power distributor 14.

Next, FIG. 2 is a flowchart showing the calculation process of the present invention, and shows the case where the ignition timing is calculated for each ignition.

First, at P□, the ignition timing is calculated (calculated value FADV) based on the above-mentioned signals S□ to S4.

Next, in P2, the limit range, that is, the upper limit value Lu (limit when the current ignition timing is more advanced than the previous one) of the allowable range of the difference between the above and the current ignition timing, and the lower limit value L/(the limit when the current ignition timing is slower than the previous one) (limit when angular) is calculated.

The upper limit value Lu and lower limit value Ll are set within a range that does not impair driveability or stability, depending on engine operating variables such as rotational speed, load, engine temperature, and battery voltage.

(Details on how to set Lu and Ll will be described later).

Next, in P3, the calculated value FADV and the previous pronunciation value PA
Find the difference X (X = FADV - PADV) with DV, and calculate the difference X
If is within the limit range (L/<X<Lu), go directly to P6, if the difference X is greater than the upper limit (Lu≦X), go to P6,
and, if the difference X is less than the lower limit (X≦−L7), the data is sent to P4.

In P, the value obtained by adding the upper limit value Lu to the previous value PADV is sent to P6 as the current value FADV, and in P4, the value obtained by subtracting the lower limit value Ll from the previous value PADV is sent to P6.

Next, in P6, the current value FADV is converted to the previous value PAD.
It is rewritten as V and stored, and FADV is outputted as the ignition timing at P7.

The calculations from 5TART to END described above are repeated for each ignition (every 120 degrees of crank angle in the case of a 4-cycle, 6-cylinder engine) in synchronization with the engine rotation.

Next, FIG. 3 is a flowchart showing another calculation process of the present invention, in which the ignition timing calculation is not synchronized with the engine rotation (
For example, this example shows a case where the process is performed at a fixed period.

The flowchart of FIG. 3 is the flowchart of FIG. 2 with P6 of the rewriting process removed, and the rewriting process is performed in synchronization with the rotation by P8 of a separate system.

In other words, in Fig. 3, the ignition timing is calculated not in synchronization with the rotation, but in synchronization with, for example, a clock signal of a constant cycle, but only the rewriting of the previous value and the current value is performed in synchronization with the rotation. The configuration is such that it is performed every period (for example, every 120 degrees).

Next, the upper limit value Lu and the lower limit value Ll will be explained.

Fig. 4 is a diagram showing the relationship between the reference angle signal A and the primary current B of the ignition coil.
, M2. A case will be exemplified in which the current ignition and the next energization are set at that point when M3... is output.

First, Fig. 4A is an example of normal operation, and the ignition advance angle is BT.
The case where DC40' (40° before top dead center) and dwell angle (energization angle) are constant at 40° are shown.

As can be seen from Fig. 4A, when the reference angle signal M0 is obtained, the current ignition timing Tn and the next energization timing TN2 (M
20° before 2).

Next, Figure 4 shows an example where energization becomes impossible due to a sudden change in the ignition advance angle. Indicates a sudden change in condition.

In this case, the current ignition timing TF3 and the next energization timing TN4 are set when the reference angle signal M3 is given, and the next ignition timing TF is set when the reference angle signal M3 is given.
4 and the next energization timing TN.

However, since the ignition advance angle and dwell angle suddenly change from the reference angle signal wind, the next ignition timing TF4 will be earlier than the next energization timing TN4, making ignition impossible.

Therefore, when setting the upper limit (red u) and lower limit L/ of the ignition timing change range to a constant value, set it at least within a range that does not cause ignition failure as described above, that is, a range where the energization timing is always earlier than the ignition timing. Just do it.

Next, a case will be described in which the upper limit value Lu and the lower limit value Lll are changed in accordance with the operating variables.

The energization time of the ignition coil varies depending on the required ignition energy.

That is, in a region where the required energy is large due to unstable combustion, such as during idling, it is necessary to lengthen the energization time.

However, since the rotational speed is low, even if the energization time is long, the dwell angle will be a small value.

Therefore, if the ignition advance angle changes significantly under such conditions, the energization time will change greatly, which increases the risk of misfire.

On the other hand, when the rotational speed is high, the dwell angle becomes short as the current application time even for dogs.

Therefore, even if the ignition advance angle changes considerably, the dwell angle is originally large, so the change in the energization time will be small.

As mentioned above, while the ignition advance angle is changing, there is a close relationship with the dwell angle, and the required dwell angle is determined according to each operating variable. If it is determined according to the operating variables, the ignition advance angle can be changed most quickly without fear of misfire.

Note that the dwell angle is mainly influenced by the rotational speed, load, engine temperature, and battery voltage, so if the upper limit L and lower limit of the limit range are set based on these operating variables, the dwell angle can be efficiently It is possible to control the ignition advance angle.

As can be seen from the above explanation, it is clear that what has been said regarding the restriction on changes in the ignition advance angle can also be applied to changes in the dwell angle.

As explained above, according to the present invention, there is no fear that the ignition timing will suddenly change discontinuously when the operating condition changes, and therefore the change in generated torque becomes smooth, improving drivability and stability. Since the angle does not become unstable, there is no risk of misfire, and the ignition timing can be changed most quickly without the risk of misfire.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, FIGS. 2 and 3 are flowcharts showing the calculation process of the present invention, FIG. 4 is a relationship diagram between the reference angle signal and the primary current of the ignition coil, and FIG. 5
The figure is a diagram showing the overall configuration of the present invention. Explanation of symbols, 1... Arithmetic unit, 2... Arithmetic device, 3 to 5... Table, 6...
Memory, 7...Rotation sensor, 8...Negative pressure sensor, 9...Temperature sensor, 10...
・Idle switch, 11...Reference angle sensor,
12...Unit angle sensor, 13...Ignition coil, 14...Distributor, 15-20...
...Spark plug.

Claims (1)

[Claims] 1. In an electronic ignition timing control device that calculates ignition timing in synchronization with engine rotation or periodically at regular intervals based on various operating variables of the engine, the ignition timing used in the previous ignition is memorized. a storage means, a difference calculation means for calculating the difference between the previous ignition timing and the currently calculated ignition timing, and detecting at least one operating variable among rotational speed, load, engine temperature, and battery voltage. detection means;
A limit range calculation means that calculates a limit range according to the operating variable detected by the detection means, and if the above difference is within the above limit range, the current calculated value is used as the ignition timing, and the above difference is the limit range. It is equipped with a limiting means that outputs a limited value as the ignition timing so that the difference becomes the upper limit when it is above the upper limit of the range, and so that the difference becomes the lower limit when it is below the lower limit. An ignition timing control device characterized in that the difference between the ignition timing and the ignition timing of the ignition timing is limited to within a limit range that varies depending on the operating variable detected by the detection means.