JPH01237357A - Ignition timing controller of engine - Google Patents

Abstract

PURPOSE:To prevent any drop in engine output, in the case of an ignition controller by which the ignition timing of an engine is delayed when presence of knocking is acknowledged, by providing such a means as capable of making correction so that a knocking acknowledge level may be raised in an operational range where the delay angle of an ignition timing is more than a preset value. CONSTITUTION:A basic ignition timing is calculated by a control unit 14 during engine run from a basic fuel injection quantity calculated in response to the state of the engine run and number of revolutions of an engine. Also when the present state of engine run stays in a knock zone, a correction amount of knocking acknowledgment level is calculated on the basis of the delay angle of the ignition timing in the previous cycle. Subsequently, the knocking acknowledgment level obtained by applying integral processing to the output of a knock sensor 13 is corrected on the basis of said correction amount and the knocking acknowledgment level Vr after correction is compared with output Vn of a knock sensor 10. Generation of knocking is acknowledged subject to Vn>=Vr, and the final ignition timing is calculated by calculating the delay angle and addition it to the previous delay angle.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an ignition timing control device for an engine that retards ignition timing when the occurrence of knocking is detected.

Prior Art The knocking judgment level obtained by integrating the output of the knock sensor that detects engine vibration is compared with the output of the 7-trick sensor, and if the knock sensor output exceeds the knocking judgment level, knocking is determined and the engine is There are known knocking control devices that control the ignition timing of the
46 etc.).

Problems to be Solved by the Invention However, when knocking is detected, knocking can be prevented by retarding the ignition timing, but if the ignition timing is retarded, the engine It has been observed that the frequency of vibrations caused by combustion changes and the frequency level near the knocking detection frequency increases, resulting in a false determination that knocking has occurred even though knocking has not occurred. As a result, the ignition timing was retarded one after another, resulting in a significant reduction in engine output. That is, when knocking occurs under normal operating conditions, engine vibrations with a frequency around 3.5 Kflz occur, so the bandpass filter filters out the 3.5 Kflz of the engine vibrations detected by the knock sensor.
Only frequency components in a specific range including KHz are selectively extracted, and knocking is determined to have occurred when the detected vibration exceeds a predetermined knocking determination level. However, considering various operating conditions, The frequency of engine vibration due to knocking may be higher or lower than 3.5 KHz, so instead of just vibrations at frequencies around 3.5 KHz, a bandpass filter can be used to reduce vibrations from 1 to 6 KHz.
It was common to detect the occurrence of knocking by extracting vibrations at a frequency of Hz. However, when the occurrence of knocking is detected and the ignition timing is retarded, the vibrations at a frequency level around 4.5 KHz increase due to engine combustion, so even if no non-kinking occurs, However, the system often incorrectly determines that knocking has occurred, and as a result, the ignition timing is successively retarded, resulting in a significant drop in engine output.

OBJECTS OF THE INVENTION An object of the present invention is to provide an ignition timing control device for an engine that can accurately detect the occurrence of knocking and retard the ignition timing only when knocking occurs.

SUMMARY OF THE INVENTION This object of the present invention is achieved by providing means for correcting so that the horn kink determination level for non-kink detection becomes high in an operating range where the amount of retardation of ignition timing is equal to or greater than a predetermined value.

According to the present invention, even if the ignition timing of the engine is retarded and vibrations with a frequency around 4.5K) Iz occur due to combustion in the engine, in such a case, the horn kink determination level is set higher. This prevents vibrations caused by combustion in the engine from being mistakenly determined to be vibrations caused by knocking, and also prevents the ignition timing from being unnecessarily retarded, thereby preventing a decrease in engine output.

In another preferred embodiment of the present invention, the means for correcting the knocking determination level allows only vibration components in a narrow band of frequencies including frequencies around 4.5 KHz to pass when the retard amount is equal to or greater than a predetermined value. Using the knocking judgment level obtained by integrating the output of the bandpass filter, when the retardation amount is less than a predetermined value, the knocking judgment level is obtained by integrating the output of the bandpass filter that passes vibration components of a wider frequency band. The knocking determination level is configured to be corrected by using the knocking determination level. In this way, by configuring the knocking determination level correction means, it is possible to more appropriately correct the erroneous determination of knocking due to engine vibrations with a frequency around 4 or 5 Kflz, which is caused by retarding the ignition timing when knocking occurs. It becomes possible to prevent this.

Example Hereinafter, an example of the present invention will be described based on the accompanying drawings.
Add detailed explanation.

FIG. 1 is an overall schematic diagram of a rotary engine including an engine knocking detection device according to an embodiment of the present invention.

In FIG. 1, a rotary piston engine E includes a rotor housing 1 having a trochoid inner peripheral surface 1a,
A casing 3 consisting of side housings 2 located on both sides of the casing 3, and a rotor 5 that rotates planetarily around an eccentric shaft 4 while sliding its top edge on the trochoid inner circumferential surface 1a.
It is composed of. A side intake port 6 is opened in the wall surface of the side housing 2.
A fuel injection valve 8 is provided in the intake passage 7 connected to the engine, and spark plugs 9a and 9b are provided in the trochoid inner peripheral surface 1a of the low-cool housing 1. The rotary piston engine E configured in this way has a rotor 5
According to the planetary rotational motion of A series of steps for discharging gas from the exhaust port 11 to the exhaust passage 12 is repeated. A knock sensor 13 is provided on the outer wall of the rotor housing 1. The output signal of the knock sensor 10 is manually input to the control unit 14, and the output signal of the knock sensor 10 is input to the control unit 14, and the output signal is sent to the spark plugs 9a, 9b.
The ignition timing of is controlled by the control unit 14. 15 is a lubricating oil supply valve.

FIG. 2 is a block diagram of an engine ignition timing control device provided in the control unit 14 according to an embodiment of the present invention.

In FIG. 2, the engine ignition timing control device 20 includes:
A band pass filter 2 that selectively passes only the frequency components of 1 to 5 KHz from the output signal of the knock sensor 13.
1. An integration circuit 22 that integrates the output signal of the bandpass filter 21 and generates a knocking determination level signal Vref.
, the output signal Vn of the bandpass filter 21 and the integrating circuit 2
The knocking determination level signal Vref output from 2 is compared with Vr obtained by correcting it according to the amount of retardation of the ignition timing, and if the output signal Vn is equal to or higher than the knocking determination level signal Vr, knocking has occurred. The computer unit 24 determines this, retards the ignition timing, and outputs an ignition signal to the Eve knife 23.

FIG. 3 is a flowchart showing a method of controlling the engine ignition timing control device according to the embodiment of the present invention shown in FIG.

First, an engine rotation speed detection signal detected by an engine rotation speed sensor (not shown) and an intake air amount detection signal detected by an air flow sensor are read into the control unit 14, the basic fuel injection amount Tp is calculated, and the engine rotation speed is The basic ignition timing IGB is calculated from the number and the basic fuel injection amount Tp. Next, the control unit 14 determines whether the operating state is in the knock zone based on the read engine speed and the calculated basic fuel injection amount Tp.

As a result, when it is determined that it is not in the knock zone, the control unit 14 calculates the final ignition timing IG by adding the normal correction C to the basic ignition timing IGB according to the following formula, and calculates the final ignition timing IG. Output to.

IG=lGB +IGN +C (1) On the other hand, when it is determined that the knock zone is present, the control unit 14 performs a preliminary adjustment based on the ignition timing retard amount IG in the previous cycle. , the knocking determination level correction amount A is calculated using the stored map. FIG. 4 shows an example of a knocking judgment level correction amount calculation map, in which the knocking judgment level correction amount A
is set to zero when the ignition timing retard amount IG is below a predetermined value, increases linearly when it exceeds a predetermined value, and becomes constant when it reaches a predetermined value.

When the knocking determination level correction amount A is calculated in this way, the knocking determination level Vr is calculated using the following equation.

Regarding Vr = Vref + A, the computer unit 24 compares the output Vn of the knock sensor 0 that has passed through the bandpass filter 21 with the knocking determination level Vr.

As a result, when Vn≧Vr, it is determined that knocking has occurred, and the retard amount △IGR is calculated using the knob to calculate the retard amount, and this is added to the previous retard amount, and the equation (1) is calculated. The final ignition timing is calculated and output to the Eve knife 23.

On the other hand, when Vn≦Vr, it is determined that knocking has not occurred, and the advance angle amount IG is calculated using the advance angle amount calculation map, and this is subtracted from the previous retard amount. The current retard amount is calculated so that the ignition timing is advanced from the previous one, and the final ignition timing is calculated using equation (1) and output to the Eve knife 23.

As described above, in this embodiment, while the ignition timing retardation amount IGN is small, the occurrence of knocking is determined using the normal knocking determination level, and the ignition timing retardation amount IG becomes large. Therefore, in operating conditions where engine vibrations at a frequency around 4.5 KHz increase beyond a predetermined value, the knocking determination level is corrected to be higher, which prevents erroneous determination that horn kink has occurred. be done.

FIG. 5 is a block diagram of an engine ignition timing control device provided in the control unit 14 according to another embodiment of the present invention.

In FIG. 5, the engine ignition timing control device 20 is
A band pass filter 3 that selectively passes only frequency components of 1 to 5 KHz from the output signal of the knock sensor 13.
The output signals of the bandpass filter 32 and bandpass filter 31.32, which selectively pass only the frequency components of 1 and 3.5 to 5KHz, are integrated to produce a first knocking determination level signal vr1 and a second knocking determination level signal, respectively. Integrating circuits 33 and 34 that generate the signal Vr2, the output signal Vn of the bandpass filter 31, and the first knocking determination level signal Vr output from the integrating circuit 33 or 34, or the second knocking determination level signal Vr2
The output signal Vn of the bandpass filter 31 is compared with the first knocking determination level signal Vr to determine whether knocking has occurred.

Alternatively, when the second non-kink determination level signal vr2 is exceeded, the computer unit 24 determines that knocking has occurred, retards the ignition timing, and outputs an ignition signal to the igniter 23.

FIGS. 6(a) and 6(b) are graphs showing the characteristics of bandpass filters 31 and 32, respectively. 6th
As shown in FIG. 3(a), the bandpass filter 31 has a characteristic of passing only vibrations in the frequency band of 1 to 6 kHz, and the bandpass filter 32 has the characteristic of passing only vibrations in the frequency band of 1 to 6 kHz.
As shown in b), it has a characteristic of passing only vibrations in the frequency band of 3°5 to 5 KHz.

FIG. 7 is a flowchart showing a method of controlling the engine ignition timing control device according to the embodiment of the present invention shown in FIG.

In FIG. 7, first, an engine rotation speed detection signal detected by an engine rotation speed sensor (not shown) and an intake air amount detection signal detected by an air flow sensor are
Control Unison) 141: The basic fuel injection amount Tp is calculated, and the basic ignition timing I G B is calculated from the engine rotation speed and the basic fuel injection amount Tp. Next, the control unit 14 determines whether the operating state is in the knock zone based on the read engine speed and the calculated basic fuel injection amount Tp.

As a result, when it is determined that it is not in the knock zone, the control unit 14 calculates the final ignition timing IG by adding the normal correction C to the basic ignition timing IGB according to equation (1), and Output to.

On the other hand, when it is determined that the engine is in the knock zone, the computer unit 24 compares the ignition timing retard amount IG in the previous cycle with a pre-stored predetermined value α.

As a result, when the retardation amount IGN is large and equal to or greater than the predetermined value α, engine vibration at a frequency around 4.5 KHz increases due to engine combustion. Using the second knocking judgment level signal Vr= obtained by integrating the output of the bandpass filter 32, which has the characteristic of passing only vibrations in a band, by the integrating circuit 34, the output Vn of the bandpass filter 31 and the second knocking judgment level are determined. It is determined whether or not the difference S from the signal Vr2 is greater than or equal to a predetermined value β determined in advance experimentally, thereby determining whether or not knocking has occurred.

In this embodiment, it is set to β-0.

On the other hand, the retard amount IGN is not so large,
When the value is less than the predetermined value α, 4.
Since it is considered that engine vibrations at frequencies around 5 KHz will not increase, the output of the band pass filter 31, which has a characteristic of passing only vibrations in the frequency band of 1 to 5 KHz, is integrated by an integrating circuit 33. Using the obtained first knocking determination level signal Vr, the output Vn of the bandpass filter 31 and the first knocking determination level signal Vr are determined.
, It is determined whether or not knocking has occurred depending on whether the difference S between the two is positive or not.

As a result of determining whether knocking has occurred in this manner, when it is determined that knocking has occurred, the computer unit 24 calculates the retard amount ΔIGR using the retard amount calculation map stored in advance, and calculates the retard amount ΔIGR. In addition to the previous retard amount, the final ignition timing is calculated using equation (1) and output to the igniter 23.

On the other hand, when it is determined that knocking has not occurred, IGA is calculated for the advance angle amount using the advance angle amount calculation map stored in advance, and the ignition timing is advanced from the previous time. Subtract this from the previous retard amount,
The current retard amount IG,l is calculated, and the final ignition timing is calculated using equation (1) and output to the igniter 23.

As described above, in this embodiment, in an operating region where the amount of retardation of the ignition timing is large and engine vibration at a frequency around 4.5 KHz increases, the knocking determination level is set in the frequency band of 3.5 to 5 KHz. Since the second knocking determination level signal Vr2 obtained by integrating the output of the band-pass filter 32, which has a characteristic of passing only vibrations of , in the integrating circuit 34, is used, erroneous determination of knocking is prevented.

The present invention is not limited to the above-mentioned examples, but various modifications can be made within the scope of the invention described in the claims, and these are also included within the scope of the present invention. Needless to say.

Effects of the Invention According to the present invention, there is provided an ignition timing control device for an engine that can accurately detect the occurrence of knocking, and therefore prevents a decrease in engine output without unnecessarily retarding the ignition timing. becomes possible.

[Brief explanation of the drawing]

FIG. 1 is an overall view of an engine including an ignition timing control device for a rotary engine according to an embodiment of the present invention, and FIG.
FIG. 3 is a block diagram of the ignition timing control device for an engine according to an embodiment of the present invention, and FIG.
The figure is a graph showing an example of a knocking determination level correction amount calculation map. FIG. 5 is a block diagram of an engine ignition timing control device according to another embodiment of the present invention, and FIG.
FIG. 5 is a graph showing the characteristics of the bandpass filters 31 and 32 used in the embodiment, and FIG. 7 is a flowchart of the ignition timing control device for the engine. E... Rotor'J-piston engine, 1... Rotor housing, 1a... Trochoid inner peripheral surface of rotor housing, 2
...Side housing, 3...Casing, 4...Eccentric shaft, 5...Rotor, 6...Side intake port, 7...Intake passage,
8...Fuel injection valve, 9a, 9b...Spark plug, 10...Working chamber, 11...Exhaust port, 12...
- Exhaust passage, 13... Knock sensor, 14... Control unit, 15... Lubricating oil supply valve, 20... Engine ignition timing control device, 21.31.
32...Band pass filter, 22.33.34...
・Integrator circuit, 23...Igniter, 24...Computer unit.

Claims (1)

[Claims] Engine ignition timing control that compares a knocking determination level with the output of a knock sensor, determines that knocking has occurred when the knocking sensor output exceeds the knocking determination level, and retards the engine's ignition timing. An ignition timing control device for an engine, characterized in that the device is provided with means for correcting the knocking determination level so that it becomes high in an operating region where the amount of retardation of the ignition timing is equal to or higher than a predetermined value.