JPH0350908B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ignition timing control device for an engine that controls ignition timing depending on the occurrence of knocking.

As a conventional example of an ignition timing control device for this type of engine, the one shown in Japanese Patent Application Laid-Open No. 162032/1983 is known, but the ignition timing control device shown in this publication does not cause engine vibrations such as knocking. Even though there are vibrations caused by nozzles other than knocking, all engine vibrations above a certain level are detected as knocking vibrations, and if the detection rate of knocking vibrations is greater than a preset reference value, the ignition is activated. Since the ignition timing is delayed and the ignition timing is advanced if it is smaller than the reference value, if there is nozzle vibration above a certain level, even if no knocking is actually occurring, this can be detected as knocking. As a result, there was a problem in that the unnecessary retardation of the ignition timing caused a loss in engine output.

In view of the problems of conventional engine ignition timing control devices as described above, the present invention provides an engine that improves the combustion characteristics and output characteristics of the engine by preventing unnecessary ignition timing retardation. The purpose of this device is to provide an ignition timing control device that includes a vibration sensor that outputs a signal corresponding to engine vibration, an operating state sensor that detects the operating state of the engine, and basic information for each engine operating state. A first storage device that stores the ignition timing in advance; a second storage device that stores the frequency of occurrence of engine vibration of a predetermined level or higher relative to the amount of ignition timing retardation for each engine operating state; an effective ignition timing calculating means for calculating an effective ignition timing from the basic ignition timing obtained from the first storage device and a retard amount at the previous ignition in the operating state; ignition execution means for executing the ignition; vibration determination means for detecting the occurrence of engine vibration accompanying the ignition execution; Increasing correction is made, and when vibration does not occur, reduction correction is made by a predetermined value, and this is
vibration occurrence frequency updating means for updating and storing in a storage device as the latest vibration occurrence frequency in the operating state, and increasing a previous retard amount in the operating state stored in the second storage device by a predetermined value when vibration occurs; a retard amount updating means that corrects the retardation amount and also decreases the retardation amount by a predetermined value when vibration does not occur, and updates and stores this in the second storage device as the latest retardation amount in the operating state; a comparison means for comparing the latest vibration occurrence frequency in the stored operating state with a vibration occurrence frequency corresponding to a retardation amount that is larger than the latest updated retardation amount by a predetermined amount; As a result, if the deviation is other than zero, the above control is continued as is, and if it is zero, the retard amount after the above update is corrected to the decreasing side, and this is updated and stored in the second storage device. The present invention is characterized by comprising a control circuit having control continuation means for subsequently continuing the above control.

The ignition timing control device for an engine according to the present invention will be described below based on an embodiment shown in the accompanying drawings. First, prior to explaining the configuration of the ignition timing control device, the technical background on which the present invention is based will be explained. To explain, this invention detects engine vibration directly from the engine using a vibration sensor. There are two causes of engine vibration, one of which is knocking vibration caused by premature ignition timing (excessive ignition advance). The other one is noise vibration other than knocking, so in order to control the ignition timing more accurately depending on the engine operating condition, it is necessary to clearly distinguish between knocking vibration and noise vibration and respond to knocking vibration. This was done with the focus on the need to perform ignition timing control.

While searching for a method to distinguish between this knocking vibration and noise vibration, the inventor discovered that since knocking vibration is caused by premature ignition timing, the inventor decided to delay the ignition timing (increase the amount of ignition retardation). However, since noise vibration is a phenomenon unrelated to ignition timing, it cannot be reduced no matter how much the ignition timing is delayed. We came to the conclusion that it should be possible to clearly distinguish between knocking vibration and noise vibration by examining the frequency of occurrence of engine vibration above a certain level when changing the engine vibration.

Furthermore, in order to understand this quantitatively, we plotted the ignition timing retard amount on the horizontal axis and the frequency (probability) of occurrence of engine vibration above a certain level on the vertical axis. When the frequency of engine vibration was investigated, as shown in Figure 2, as the amount of retardation gradually increased from 0, the frequency of engine vibration gradually decreased, and after reaching a certain amount of retardation θ _K. It was possible to obtain a curved characteristic line l in which the frequency of occurrence of engine vibration is parallel to the horizontal axis and does not change at all in each operating state, no matter how large the retardation amount is.

From this characteristic diagram l, it can be seen that in the region of the retardation amount smaller than the retardation amount θ _K corresponding to the bending point A of this characteristic diagram l, as the retardation amount is increased, the engine vibration increases above a certain level. Since the frequency of occurrence of has decreased, it means that knocking vibration was occurring in this region (this region is called a knocking occurrence region), and the retardation amount θ _K corresponding to this bending point A In the region where the retardation amount is larger, the frequency of engine vibration does not change even if the retardation amount is increased, which means that knocking vibration is not occurring in this region, only noise vibration is occurring. (This area is called the knocking non-occurrence area).

Therefore, in order to maximize the engine output without causing knocking, it is necessary to adjust the retard amount to correspond to each operating state of the engine.
What is necessary is to make it as close as possible to the bending point A of the characteristic diagram l as shown in the figure.

The ignition timing control device of the present invention is based on the above-mentioned technical background, and is designed to always perform ignition near the appropriate amount of retardation at which knocking does not occur.In order to obtain this appropriate amount of retardation, Learning control of ignition timing is performed.

Hereinafter, the engine ignition timing control device of the present invention will be described using an ignition timing control device Z installed in an automobile engine 1 shown in FIG. 1 as an example. A crank angle sensor 5 for detecting the crank angle of the engine 1, a negative pressure sensor 6 for detecting the negative pressure in the intake pipe 2, and a vibration sensor 7 for detecting engine vibration are provided. . Among these sensors, a crank angle sensor 5 and a negative pressure sensor 6 constitute an operating state sensor that detects the operating state of the engine. Based on the signals input from each sensor, the control circuit 10 controls the ignition coil 8 to control the ignition timing of the spark plugs 3, 3, . . .

Further, as described above, this ignition timing control device Z is configured to perform ignition at an ignition timing near the retard amount corresponding to the bending point A of the characteristic diagram 1 (FIG. 2) in each operating state. In order to obtain the characteristic diagram l in each operating state, two storage devices,
That is, as shown in FIG. 5, a read-only first storage device has a basic ignition timing map in which reference ignition timing _θB is written in correspondence with each operating state of the engine 1, that is, engine speed N and manifold negative pressure P. (ROM) 11, and a table numerically expressing the correlation between the retard amount and the frequency of knocking (corresponding to the characteristic diagram l) as shown in FIG. A second storage device 12 for both reading and writing has a knock frequency table written in correspondence with the operating state of the engine, and by updating and setting each table value in the knock frequency table to an appropriate value for each ignition, Finally, the bending point A of the early characteristic diagram l in each operating state is found, and thereafter ignition is performed at the ignition timing of the retard amount corresponding to this bending point A.

Below, the procedure for setting the appropriate ignition timing will be explained with reference to the control flow chart shown in FIG. Set the ignition timing corresponding to the area. That is, the eighth
As shown in the figure, the crank rotation period T ₀ (=t ₂ − _{t 1} ) is calculated from time t ₁ at the previous crank angle BTDC 90° and time t ₂ at the current BTDC 90° (step 21).
Also, from this rotation period T ₀ to the current rotation speed N
(Step 22), and further calculate this rotation speed N
The current operating range of the engine is determined from the manifold negative pressure P detected by the negative pressure sensor 6 (step 23) (step 24), and the current operating range is determined from the basic ignition timing map in the first storage device 11. Read out the basic ignition timing θ _B corresponding to (step
twenty five). For example, if the manifold negative pressure is within the range of Pm _-1 to Pm and the engine speed is Nn _-1 to Nn
If it is within the range of , the basic ignition timing is θ _Bo , _n .

Next, this basic ignition timing θ _B and the retard amount θ _K previously set by the control procedure as described later (if this control is the first time, this retard amount θ _K will be 0). ), the current ignition timing θ (=θ _K +θ _B ) is calculated (step 26).

Once the ignition timing θ is determined, an ignition time corresponding to this ignition timing is calculated (steps 27, 28), and ignition is performed at this ignition time (step 29).
Furthermore, after the ignition is executed, the time to start energizing the ignition coil 8 is calculated in preparation for the next ignition (steps 30, 31), and energization is started at the predetermined energization start time (step 32).

When the spark plug 3 is ignited and combustion occurs in the cylinder, engine vibration occurs, and vibrations above a certain level are detected by a vibration sensor 7.
The knock intensity I _K is read from the output of the vibration sensor 7 (step 33), and based on this it is determined whether a knock has occurred (step 34). That is, when the knock strength I _K =0, it is determined that no knock has occurred, and conversely, when I _K >0, it is determined that a knock has occurred.

Once the presence or absence of knock occurrence is confirmed by the knock judgment, next, the knock frequency table (Fig. 6) containing the table (Fig. 7) in which the knock occurrence frequency and retardation amount in each driving range is written is checked. The retard amount θ _K and the knock frequency Cl of each table are appropriately corrected depending on the presence or absence of a knock and are rewritten as a new retard amount θ _K and knock frequency Cl.

That is, if it is determined that a knock has occurred as a result of the knock judgment, the previously set retardation amount θ _K and the retardation are calculated from the table value corresponding to the operating state in the knock frequency table, for example Tab (n, m). The knock frequency Cl corresponding to the amount θ _K is read out, and first, the previous knock frequency is
Add 0.01 to Cl to obtain the new knock frequency Cl (step 35). In addition, when a knock occurs in this way, the value of the knock frequency is increased by 1%, but in this case, the knock frequency Cl must be a value of 0≦Cl≦1, so check whether Cl>1. Check (step 36), and if Cl > 1, forcefully
Set Cl=1 (step 37).

Furthermore, since a knock occurred at the previously set retard amount θ _K , in order to eliminate this knock it is necessary to increase the retard amount in accordance with the knock strength I _K value. A new retard amount θ _K is obtained by adding a corrected retard amount K·I _K (K: retard constant) to the angular amount θ _K (step 38).

On the other hand, if it is determined that there is no knock, the new knock frequency Cl is set to the value obtained by subtracting 0.01 from the previous knock frequency Cl by performing the operation that is completely opposite to the operation described above when it was determined that there is a knock. (Cl−0.01)
In addition, a new retard amount θ _K is set to a value (θ _K −Δθ _A ) that is delayed by a constant value Δθ _A from the previous retard amount θ _K (steps 39 and 40).

Next, determine whether the new retard amount θ _K obtained as described above is in the knock occurrence region or in the non-knock occurrence region (in other words, on which side of the bending point A of the characteristic curve l is it located?) is determined, and the retard amount θ _K is corrected as necessary.

That is, the knock frequency Cl (updated value) corresponding to the retard amount θ _K of the predetermined table Tab (n, m) of the knock frequency table corresponding to the operating region and the retard angle that is one class larger than the retard amount θ _K. Difference between knock frequency (Cl+ _{1) corresponding to quantity (θK} + ₁ ) △C [=Cl−C(l+ ₁ )]
is calculated (step 41), and it is checked whether ΔC>0 (step 42) (see Figure 3).

Here, if ΔC>0, the value of the retard amount θ _K is located closer to the knocking occurrence region than the bending point A of the characteristic diagram l, and therefore there is no need to correct it. vice versa,
When △C=0, the retardation amount θ _K is determined by the characteristic diagram l
It can be seen that the engine vibration is on the non-knocking region side from the bending point A, and that the generated engine vibration is due to noise vibration. Therefore, in this case, it is necessary to reduce the retard amount, and for this reason, the new retard amount θ _K obtained by the knock judgment is reduced (advanced) by a predetermined retard amount △θ _F (θ _K
−△θ _F ) as the updated value of the retardation amount θ _K
(n, m) (step 43). In this case, since the retard amount θ _K must not be a negative value, θ _K
It is checked whether θ K <0 (step 44), and if θ _K >0, it is left unchanged, and if θ _K <0, it is further updated as θ _K =0 (step 45).

As mentioned above, every time there is ignition, a knock judgment is made on the engine vibration that occurs at that time, and the retard amount θ _K and knock frequency Cl written in the table Tab (n, m) corresponding to each operating region are updated. According to
The value of the retardation amount θ _K can be gradually focused on the retardation amount corresponding to the bending point A of the characteristic diagram l. Therefore, the more this kind of update control is repeated, the more the retardation amount θ _K and the knock frequency Cl will approach the bending point A of the characteristic diagram l, and the more the engine is operated throughout the entire operating range, the more the knock occurs. It becomes possible to operate the engine with the ignition timing near the bending point A of the characteristic diagram 1, at which the maximum engine output can be obtained without the engine turning off.

Next, to explain the effects of the present invention, the engine ignition timing control device of the present invention calculates the occurrence probability of knocking vibration and noise vibration in each operating range of the engine and the characteristics of the ignition timing retardation amount by learning. , From this characteristic, the amount of retardation is determined to be the amount of retardation corresponding to the boundary between the knocking region where knocking occurs and the knocking non-occurrence region where knocking does not occur, in other words, the maximum engine output without knocking. Since the retardation amount is as close as possible to the amount of retardation that can be obtained, even noise vibrations are detected as knocking vibrations if the engine vibration is above a certain level, and the amount of retardation of the engine's ignition timing is adjusted accordingly. This eliminates the need for a conventional engine ignition timing control device that unnecessarily increases the amount of retardation and causes a decrease in engine output, and the combustion characteristics and output characteristics of the engine can be improved accordingly. There is.

[Brief explanation of drawings]

FIG. 1 is a system diagram of an engine ignition timing control device according to an embodiment of the present invention, and FIGS. 2 and 3 are characteristic diagrams showing the correlation between the amount of retardation and the frequency of occurrence of knocks and loud noises. Figure 4 is an ignition timing control flowchart, Figure 5 is a basic ignition timing map, Figure 6 is a knock frequency table, Figure 7 is a table within the knock frequency table, and Figure 8 is a graph of crank angle and ignition coil. FIG. 3 is a diagram showing a relative relationship between energization timings. 1...Engine, 5...Crank angle sensor,
6... Negative pressure sensor, 7... Vibration sensor, 10
...Control circuit, 11...First storage device, 12...
Second storage device.

Claims (1)

[Claims] 1. A vibration sensor that outputs a signal corresponding to engine vibration, an operating state sensor that detects the operating state of the engine, and a first storage device that stores in advance the basic ignition timing for each engine operating state. a second storage device that stores the frequency of occurrence of engine vibration of a predetermined level or higher with respect to the amount of ignition timing retardation for each engine operating state; and a basic ignition value determined from the first storage device corresponding to the engine operating state. an effective ignition timing calculation means for calculating an effective ignition timing from the timing and a retard amount of the previous ignition in the operating state; an ignition execution means for executing ignition based on the effective ignition timing;
A vibration determination means detects the occurrence of engine vibration due to execution of the ignition, and when vibration occurs, increases the frequency of vibration occurrence in the previous operating state stored in the second storage device by a predetermined value, and vibration occurrence frequency updating means for reducing the frequency by a predetermined value when the vibration occurs, and updating and storing this in the second storage device as the latest vibration occurrence frequency in the operating state; The previous amount of retardation in the operating state is corrected by increasing it by a predetermined value, and when vibration does not occur, it is corrected by decreasing it by a predetermined value, and this is updated and stored in the second storage device as the latest amount of retardation in the operating state. a retardation amount updating means, a vibration occurrence frequency corresponding to the latest vibration occurrence frequency in the operating state updated and stored in the second storage device and a retardation amount that is larger by a predetermined amount than the latest updated retardation amount; and a comparison means for comparing the difference between the two, and if the deviation is other than zero as a result of the comparison by the comparison means, the above control is continued as it is, and if it is zero, the retard amount after the above update is re-corrected to the decreasing side. an ignition control device for an engine, comprising: a control circuit having control continuation means for continuing the control after updating and storing the updated information in the second storage device.