JPS6048629B2 - Engine ignition timing control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an engine ignition timing control device that retards ignition timing when knocking occurs. This relates to a control device.

Generally, the ignition timing of an engine needs to be determined depending on the engine condition so that the engine can be operated optimally.

Conventional ignition timing control devices detect the engine speed and load, advance the ignition timing when the engine speed is high, and conversely advance the ignition timing when the engine speed is low. When the load is small, the ignition timing is advanced, and when the load is large, the ignition timing is coupled, so the ignition timing can be adjusted to the minimum advance value at maximum torque.
The so-called MBT (Minimumadvance for
Best Torque). However, in operating ranges such as low engine speeds and high loads, if the ignition timing is advanced with emphasis on torque, knocking will occur before the MBT is reached, making it impossible to operate the engine stably. In order to solve this problem, a knocking detection circuit has been conventionally provided as shown in Japanese Patent Application Laid-Open No. 54-142425 or Japanese Patent Application Laid-open No. 55-5468, and when knocking occurs, the above-mentioned knocking detection circuit is activated. The ignition timing is set according to the output,
Ignition timing control devices designed to prevent knocking have been considered. By the way, when considering the mechanism of engine knocking, it differs greatly between when the engine is warmed up and when it is cold.

For example, when knocking is replaced with engine vibration, which is relatively related to knocking, when the engine is warmed up, the engine vibration gradually increases as shown in Figure 5a, and when it exceeds a certain amplitude d, knocking occurs. On the other hand, when the engine is cold, as shown in the figure, the engine vibration is small at first, but it suddenly increases and knocking occurs instantaneously. This means that when the same transient state (acceleration) occurs when the engine is warmed up and when it is cold, the time it takes to enter the knocking region is shorter when the engine is cold, where the air density is higher, than when it is warmed up, and when the engine is in the evaporation atomization state. This is thought to be because the knocking zone in the combustion chamber is smaller when the engine is cold, so the level at which knocking is triggered is smaller. However, conventional ignition timing control devices do not take into account the fact that the knocking generation mechanism differs depending on the engine temperature, and the knocking detection level is fixed with respect to the engine temperature. When the engine is warmed up (see Figure 5a), the ignition timing can be brought as close to MBT as possible to the extent that knocking occurs in the low-speed, high-load range where knocking is relatively likely to occur when the engine is warmed up. Sometimes there is a problem that the detection of knocking is too slow to prevent the occurrence of knocking.On the other hand, when the detection level B is low (see Figure 5b), it is possible to reliably prevent the occurrence of knocking when the engine is cold, but when the engine is Even though knocking had not yet occurred during warm-up, the ignition timing was retarded early and the ignition timing could not be brought closer to the MBT, resulting in a reduction in output and fuel efficiency.

This invention was made in view of the fact that the knocking characteristics depend on the engine temperature as mentioned above, and when the engine is warmed up, the detection level of the knocking detection circuit is raised to adjust the ignition timing to the very limit of knocking occurrence. M.B.T.
To provide an engine ignition timing control device which is capable of reliably preventing the occurrence of knocking by lowering the detection level of a knocking detection circuit when the engine is cold to detect knocking earlier. The purpose is

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows an engine ignition timing control device according to an embodiment of the present invention, and in the figure, 1 indicates non-. a knocking sensor made of, for example, a piezo element that detects the knocking as engine vibration; 2 a filter that extracts a vibration signal of a predetermined frequency as output A from the vibration signal of the knocking sensor 1; 3 a detection level setting circuit that sets a detection level B; 4 is a comparison circuit that compares the output A of the filter 2 and the detection level B of the detection level setting circuit 3; 5 is an integration circuit that integrates the output C of the comparison circuit 4; the circuit from the filter 2 to the integration circuit 5; This constitutes a knocking detection circuit 6 that detects engine knocking.

Further, 7 is an engine cooling water temperature sensor that detects the engine cooling water temperature, and 8 is a correction signal generator that generates a correction signal for correcting the comparison level of the comparison level setting circuit 3 according to the cooling water temperature detected by the sensor 7. The sensor 7 and the correction signal generation circuit 8 constitute a correction circuit 9 for correcting the detection level B of the knocking detection circuit 6.

Further, 10 is an engine rotation speed detection circuit that detects the engine rotation speed, and 11 is an output E of the engine rotation speed detection circuit 10.
12 is a retard amount control circuit that controls the ignition timing retard amount G according to the output F of the adder circuit 11, and 13 is a synchronization circuit according to the engine rotation. A signal generator that generates pulses, 14 is a signal generator 13
15 is an ignition circuit having an ignition switch 15a, an ignition coil 15b, and a spark plug 15c.

In the above, circuits 10, 11, 12 and igniter 1
4 constitutes an ignition timing control circuit 16 that controls the ignition timing of the engine. Next, the operation of this apparatus will be explained with reference to FIGS. 2 to 5. First, when the engine is not knocking, the engine speed detection circuit 1
0 detects the engine speed with the characteristics shown in FIG. The amount of retardation is set as the output G according to the characteristics shown in FIG.
The engine is ignited by the ignition circuit 15.

In this way, the ignition timing of the engine is controlled according to the engine speed. By the way, when the engine knocks, the knocking sensor 1 detects engine vibration and outputs a vibration signal output A shown in FIG. , the output C of the comparator circuit 4 becomes as shown in FIG. 2b, and it is detected that knocking has occurred.

This output C is then integrated by the integrating circuit 5, and its output D becomes as shown in FIG. The adding circuit 11 adds the output D of the integrating circuit 5 to the output E of the engine rotation speed detection circuit 10, and the output F is, for example, the engine rotation speed N,,N2.
Accordingly, the output F becomes as shown in FIG. 2d, and this output F is input to the retard amount control circuit 12, so that the retard amount of the output H of the igniter 14 becomes as shown in FIG. 2e. When knocking is detected in this way, the ignition timing is retarded by the amount of retardation determined by the engine speed, plus the amount of output D shown in Figure 2c.
This prevents knocking from occurring. When the engine is warmed up, the detection level B of the knocking detection circuit 6 is set high as shown in FIG. The ignition timing is set to M until it reaches the knocking limit.
It can be made close to BT and is advantageous in terms of output and fuel efficiency. On the other hand, when the engine is cold, the engine coolant temperature sensor 7 detects a decrease in the coolant temperature, and the correction signal generation circuit 8 generates a correction signal to adjust the detection level B of the detection level setting circuit 3 to the fifth level. lower as shown in Figure b. Therefore, when knocking is about to occur when the engine is cold, the knocking is detected as soon as possible, and the ignition timing is retarded early to reliably prevent knocking. In the above embodiment, an ignition timing control circuit that controls the ignition timing based only on the engine speed is shown, but it is also possible to control the ignition timing depending on the intake negative pressure, The ignition timing may be controlled depending on both the negative pressure and the negative pressure.

As described above, according to the present invention, in the engine ignition timing control device that retards the ignition timing when knocking occurs, the detection level of the knocking detection circuit is adjusted when the engine is warmed up and when the engine is cold. When the engine is warmed up, the detection level is raised to bring the ignition timing close to the knocking limit, and when the engine is cold, the detection level is lowered to quickly detect knocking and ensure that knocking is prevented. This has the effect of enabling efficient engine ignition timing control.

[Brief explanation of drawings]

FIG. 1 is a block circuit diagram of an engine ignition timing control device according to an embodiment of the present invention, FIG. 2 a to e are signal waveform diagrams of each part of FIG. 1, and FIG. Engine speed-output voltage characteristic diagram of the detection circuit, Figure 4 is the first
The input voltage vs. retardation amount characteristic diagram of the retardation amount control circuit shown in FIG. 6... Knocking detection circuit, 9... Correction circuit, 1
6...Ignition timing control circuit, B...Detection level.

Claims (1)

[Claims] 1.Equipped with an ignition timing control circuit that controls the ignition timing of the engine according to the engine speed or load, and a knocking detection circuit that detects engine knocking, and when knocking occurs, the ignition timing control circuit An ignition timing control device for an engine that retards ignition timing is provided with a correction circuit that increases the knocking detection level of the knocking detection circuit when the engine temperature is high and lowers it when the engine temperature is low based on a signal related to the engine temperature. An engine ignition timing control device characterized by: