JPH076872B2 - Engine knocking detector - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a device for detecting engine knock.

(Prior Art) An engine including a knock sensor for detecting a knocking state of the engine and controlling the engine based on a signal from the knock sensor to suppress knocking is known.

For example, JP-A-58-28597 discloses an example of a knocking control method. In this disclosed method, the engine is equipped with a vibration detecting element for detecting vibration, and the average value of the amplitude values of the electric signal from this vibration detecting element in a plurality of ignition cycles is calculated separately for each cylinder. The occurrence of knocking is stored for each cylinder, and the ignition timing is controlled in the retard direction for each cylinder.

Further, Japanese Patent Laid-Open No. 57-208432 also discloses a similar knocking detection device.

(Problems to be Solved) In the engine disclosed in JP-A-58-28597, knocking is detected for each cylinder, and ignition timing control corresponding to each cylinder is performed. ,
It is possible to perform knocking control with higher accuracy than a method in which knocking control is uniformly performed for each cylinder. In this type of knocking control device, knocking is detected by focusing on the fact that the vibration level in a normal operating state in which knocking does not occur and the vibration level when knocking occurs are different. Therefore, in order to perform appropriate knocking control, it is premised that the vibration level in a normal state where knocking does not occur is accurately grasped. In this case, the engine vibration level differs between when the engine is in the combustion stroke and when it is in the non-combustion period, but knocking occurs during the combustion period.Therefore, when detecting knocking, the vibration level during the combustion period is used as a reference. It is desirable to judge.

In the engine disclosed in JP-A-58-28597, knocking is discriminated based on the vibration level during the combustion period, so there is an advantage that knocking can be detected accurately. However, since the vibration level during the combustion period changes as the operating state changes, setting the reference value becomes complicated, and in certain operating states, it may not be appropriate to use it as the reference value. Therefore, the disclosed knocking control device has a problem that proper knocking control cannot be performed over the entire operation range.

Further, in the method disclosed in the above-mentioned Japanese Patent Laid-Open No. 57-208432, since knocking is determined by using only the vibration level in the non-combustion period, accurate knocking determination cannot be performed. There is.

(Means for Solving Problems) As described above, the vibration level of the engine is different between the combustion period and the non-combustion period and also changes with the operating state.
Therefore, even if a certain reference for knocking determination is set based on the vibration level in the combustion period over the entire operating region, knocking cannot be accurately determined.
Therefore, in order to set an accurate knocking determination level, it is necessary to appropriately consider the vibration level in the combustion period and the vibration level in the non-combustion period according to the operating state. Furthermore, in order to perform accurate control in the entire operating region of the engine, it is necessary to increase the accuracy to a higher level corresponding to the vibration level in the non-combustion period, that is, to the accuracy corresponding to the first reference value for the vibration level in the combustion period. I need to do it.

The vibration during the combustion period is the vibration in which the combustion pressure is the vibration source, and increases as the intake air amount increases. Further, the vibrations during the non-combustion period are vibrations in which the rotating body (camshaft, crankshaft, etc.), pistons, etc. act as vibration sources, and therefore the vibrations increase as the engine speed increases.

Since knocking occurs during combustion, it is possible to improve knocking detection accuracy by using a normal vibration level (when non-knocking occurs) during the combustion period as a knocking comparison level. However, in the transitional state, the vibration level changes with the change in the intake air amount, so that the accuracy of knocking detection decreases when the vibration level in the combustion period in the steady state is used as a reference. Therefore, in the transient operation state, it is rather more accurate to set the knocking determination reference value based on the vibration level during the non-combustion period. However, if the reference value based on the non-combustion period is fixed in the transient operation state, the accuracy will decrease.

The present invention is configured from such a point of view, and corrects the knocking determination reference value in order to accurately perform knocking determination in a transient operating state, particularly during acceleration.

That is, the engine knocking detection device according to the present invention includes a vibration detection unit that detects engine vibration, and a first reference value that is output from the vibration detection unit and that generates a first reference value from the vibration level during the combustion period of the engine. A second reference value is created from the vibration level in the non-combustion period of the engine by receiving the outputs of the reference creating means and the vibration detecting means.
The reference value creating means, the operating state detecting means for detecting the operating state of the engine, and the output from the operating state detecting means, and in the steady operation of the engine, the output of the vibration detecting means and the first The output from the vibration detecting means and the second reference value are received during the acceleration operation of the engine by receiving the outputs from the first comparing means for comparing the reference value to determine knocking and the operating state detecting means. A second comparing means for comparing and determining knocking; and a knocking determining means for selecting the first or second reference value according to an operating state and comparing with a signal from the vibration detecting means to determine knocking. In addition to the above, the second reference value is corrected based on the first reference value created in the steady operation state so that the second reference value increases as the first reference value increases.

According to the present invention, in detecting knocking,
Means for creating a first reference value based on the vibration level during the combustion period and a second reference value based on the vibration level during the non-combustion period are respectively provided, and these reference levels are appropriately selected according to the operating state. I try to determine knocking. For example, during steady operation in which the vibration level changes little, the first level based on the vibration level during the combustion period
The knocking is detected according to the reference value of. Then, in a transient operating state such as during acceleration when the vibration level in the combustion period changes, knocking is determined based on the second reference value based on the motion level in the non-combustion period.

Furthermore, in order to further improve the accuracy of the second reference value, the second
The second reference value is created by correcting the reference value of 1 based on the first reference value.

(Effect of the invention) According to the present invention, since the fluctuation of the vibration level is small, it is based on the second reference value based on the vibration level during the non-combustion period that enables stable knocking determination and the vibration level during the accurate combustion period. The first reference value and the first reference value are appropriately used according to the operating state, and in a predetermined operating region such as when knocking occurs, the vibration level changes and is adopted as the reference value. Since it is not appropriate, the reference value is not created based on the vibration level during the combustion period, and the second reference value is created by correcting the first reference value based on the vibration level during the non-combustion period. There is. Therefore, according to the present invention, an appropriate reference value for knocking determination can be set through the pre-driving region, and as a result, reliable and accurate knocking detection can be performed.

(Description of Embodiments) Hereinafter, embodiments of the present invention will be described with reference to the drawings.

Referring to FIG. 1, the engine 1 of this example is a four-cylinder reciprocating engine, and each cylinder includes a piston 3 that slides inside a cylinder block 2. A space above the piston 3 constitutes a combustion chamber 4, and an intake port 5 and an exhaust port 6 are opened in the combustion chamber 4. An intake valve 7 and an exhaust valve 8 are combined with the intake port 5 and the exhaust port 6, respectively. In intake port 5,
The intake passage 9 is communicated with, and an air cleaner 10 is attached to an upstream end of the intake passage 9. An air flow meter 11 for detecting the intake air amount is arranged downstream of the air cleaner 10, and a throttle valve 12 is arranged further downstream. An intake air temperature sensor 11a for detecting the intake air temperature is attached to the air flow meter 11. A surge tank 13 is formed downstream of the throttle valve 12, and an injector 14 for injecting and supplying a fuel amount is arranged further downstream to form an intake system. The exhaust passage 15 communicates with the exhaust port 6 to form an exhaust system.

Further, an ignition plug 16 is exposed to the combustion chamber 4, and an ignition coil unit 17 is provided to control the ignition timing of the ignition plastic 16.

A water temperature sensor 19 for detecting the cooling water temperature is attached to the water jacket 18 formed in the shilling block 2, and a knock sensor 20 for detecting knocking by detecting engine vibration is attached. Furthermore, in the cylinder head of the engine 1 of this example,
A crank angle sensor 21 that detects a crankshaft rotation angle from the rotation of a camshaft (not shown) is provided. In the engine 1 of this example, a signal for identifying the supply cylinder is obtained from the signal from the crank angle sensor 21.

Further, the engine 1 of this example is provided with a controller 22 preferably including a microcomputer in order to control fuel injection and ignition timing. Further, the engine 1 of this example is provided with a knock detection circuit 23 that cooperates with the controller 22 to detect knocking.

Signals representing the intake air amount and the intake air temperature from the air flow meter 11 and the intake air temperature sensor 11a are input to the controller 22, respectively.

The controller 22 also receives a throttle opening sensor 12a for detecting the opening of the throttle valve 12, a signal from the water temperature sensor 19, a crank angle signal and a cylinder identification signal from the crank angle sensor 21, and a starter signal. It is like this. It should be noted that the signal indicating the engine vibration from the knock sensor 20 is once input to the knock detection circuit 23, is subjected to predetermined processing in the knock detection circuit 23, and then is input to the controller 22.

In the knock detection circuit 23, as the input signal from the knock sensor 20, only a signal having a frequency within a predetermined range is selected by passing through the bandpass filter 24.

In the knock detection circuit 23, the signal passed through the bandpass filter 24 is adapted to be directly input to the comparator 25, and half-wave rectification integration is performed via switches 26 and 27, which are preferably semiconductor switches. It is adapted to be input to circuits 28 and 29.

The switches 26 and 27 are selectively opened at a predetermined timing in response to a command from the controller 22, so that the signal passed through the bandpass filter 24 is activated by the switches 26 and 27 functioning as a gate circuit. It is selectively input to the half-wave rectification integration circuit 28 or 29 accordingly. Half-wave rectification integrator circuits 28 and 29 are circuits for determining the determination level for performing knock determination, and integrate the signal of the corresponding switch 26 or 27 during the open period, and switch 26 or 27 is closed. At that moment, the integrated value is input to the controller 22.

The switch 26 is opened when the cylinder is not in the combustion period, and the switch 27 is opened when the cylinder is in the combustion period. Therefore, the half-wave rectification integration circuit 28 determines the knocking determination comparison level during the non-combustion period, and the half-wave rectification integration circuit 29 determines the knocking determination comparison level during the combustion period. Then, these half-wave rectifying and integrating circuits 28 and 29 are
The knocking determination comparison level signal determined by the switch 22 is selectively output from the controller 22 to the comparator 25 in response to the operation of the switches 26 and 27, and the bandpass filter 24
Is compared with the signal after passing through, and the level of knocking is determined by this.

The signal indicating the knocking intensity I _K output from the comparator 25 is once input to the integrating circuit 30 and integrated for a predetermined time.
The period during which the signal is integrated in the integrating circuit 30 is controlled by the controller 22. Further, the controller 22 is a half-wave rectification integrating circuit 28, 29 and an integrating circuit.
A reset signal is output to 30 with a predetermined tamming to clear these circuits.

The control of this example will be described below.

FIG. 3 shows a flowchart of the background routine of the control of this example. The controller 22 constantly executes this background routine.

Referring to FIG. 3, the controller 22 first initializes the system and reads signals from various sensors.

That is, the signals from the air flow meter 11, the water temperature sensor 19, the intake air temperature sensor 11a, the starter signal for detecting the drive state of the engine, and the idle switch signal for detecting the idle state are read. Next, the controller 22 calculates the intake air amount by calculating the read data, and also calculates the change amount ΔQ _a of the intake air amount. Next, the controller 22 executes the transient determination flag setting subroutine shown in FIG. 4 to set the flag F _A for determining whether the engine 1 is in the transient state.

Referring to FIG. 4, the controller 22 determines the change amount | ΔQ _a |
Is greater than the predetermined value Kg, it is determined that the engine 1 is in a transient state, that is, in an unsteady state such as an acceleration state or a deceleration state. In this case, the flag F _A is set to 1. On the other hand, when the intake air change amount | ΔQ _a | is smaller than the predetermined value Kg, the controller 22 determines that it is in the steady state, and the flag F _A
Is set to 0. In this example, even if the flag F _A is once set to 1 after the transient state is determined, even if the intake air change amount | ΔQ _a | decreases and the engine 1 returns to the steady state thereafter. The flag F _A is kept at 1 until the combustion state of the engine 1 stabilizes after a lapse of a predetermined time. That is, when the flag F _A is set to 1, the controller 22 changes the intake air change amount | ΔQ _a |
If but becomes smaller than the predetermined value Kg, set the timer C to a predetermined value K _A, until the timer C is 0 so as to reduce the timer C for each execution of the routine, the flag F _A
Is maintained at 1.

Next, control of ignition timing as knocking control according to one embodiment of the present invention will be described.

FIG. 5 shows a flowchart of the interruption routine. The interruption routine of FIG.
Each time a cylinder identification signal generated every 0 ° is input to the controller 22, it is interrupted and executed.

Further, FIG. 6 shows a flow chart of an interrupt routine for controlling the knock detection circuit 23 to obtain an appropriate knock correction advance angle Θ _Kn and finally determining the ignition timing to be output.

The interrupt routine of FIG. 6 is executed every time the crank angle signal generated every 30 ° of crank rotation angle is input to the controller 22 regardless of the execution of the background routine of FIG. 3 and the transient determination flag setting routine of FIG. It is designed to be interrupted and executed.

When the interrupt routine of FIG. 5 is executed, the cylinder discrimination counter n and the sixth cylinder for performing knock correction control
The counter T for determining the work procedure of the routine shown in the figure is forcibly reset and set to n = 0 and T = −1, respectively.

Referring to the time charts of FIGS. 6 and 7, the controller 22 first increments the counter T by one each time this routine is executed. Since the engine 1 of this example is a 4-cycle engine, and the interrupt routine of FIG. 6 is executed every 30 ° of crank rotation, the cylinder stroke is executed every 6 times of this routine. Will be switched. Since the routine of FIG. 6 is designed to control each cylinder corresponding to the expansion stroke of each cylinder, the controller 22 sets T = 0 when the crank angle signal is input six times. Reset. Also, at this time,
Since the next cylinder starts the expansion stroke in the ignition order, the controller 22 increments the cylinder discrimination counter n by one. Further, in this routine, the cylinder identification counter m for the cylinder to start the expansion stroke next is prepared, and 1 is also added to this counter m. The engine 1 of this example has four
Since it is a cylinder engine, when the counter m reaches 4, m = 0 is set. Next, the controller 22 performs a predetermined process according to the value of the counter T.

When the counter T is 2, the controller 22 first closes the switch 27 functioning as the gate for the knock signal of the combustion period of the knock detection circuit 23 shown in FIG. 2, and the switch functioning as the gate of the non-combustion period. Open 26. Then, the controller 22 reads the integration value I _F for half-wave rectifying and integrating circuit 29 for integrating the signal from the knock sensor 20 in order to make the knock determination comparison level S _Fn cylinders each combustion period.
Further, the controller 22 uses an integration circuit 30 that represents the knock strength.
Read the integral value I _K of.

Next, the controller 22 executes a subroutine shown in FIG. 8 for determining the knock intensity and the knock correction advance angle Θ _Kn of the ignition timing to calculate the knock correction advance value Θ _Kn for each cylinder. In addition, the controller 22 has a counter T = 2.
In this state, the comparison level calculation subroutine shown in the flowchart of FIG. 9 is executed, and the knock determination comparison level S _Fn during the combustion period, the knock determination comparison level S _Fn during the combustion period, and the knock determination comparison level S _N during the non-combustion period are executed. A correction coefficient D _n between and is obtained.

When the counter T = 3, the controller 22 executes the subroutine for calculating the ignition advance control value shown in the flowchart of FIG. 10 to calculate the final ignition advance Θ _Ig .

At the counter T = 4, the controller 22 closes the switch 26 functioning as a gate during the non-combustion period and integrates the signal from the bandpass filter 24 to obtain the knock determination comparison level S _N during the non-combustion period. Circuit 28
Read the integral value I _N of. In addition, the controller 22
The subroutine shown in the figure is executed to calculate the knock determination comparison level S _N during the non-combustion period and determine the output value S _OUT to the comparator 25.

When the counter T = 5, the controller 22 outputs the knock determination comparison level output value S obtained by the subroutine of FIG.
_OUT is output to the comparator 25 and each of the integration circuits 28, 29 and 30 of the knock detection circuit 23 is reset.

At counter T = 0, the controller 22 opens the burn period gate or switch 27.

Then, when the counter T = 6, the expansion stroke of the cylinder is completed, so the controller 22 causes the counter T to end.
Is reset to 0, and the cylinder identification counters n and m
Is added one by one. As a result, when the interrupt routine of FIG. 6 is executed next, the series of operations described above is performed for the cylinder for which the expansion stroke is started next.

Next, a procedure for obtaining various variables used in the interrupt routine of FIG. 6 will be described.

First, referring to FIG. 9, a knock determination comparison level S _Fn for each cylinder and a correction coefficient D _n for calculating a knock determination comparison level S _N for a non-combustion period from the comparison level S _Fn. The procedure for obtaining is described.

In FIG. 9, the controller 22 indicates the oldest knock strength I _F stored in the map A (n, 300) that stores the signal from the integrating circuit 30 representing the knock strength I _F in the combustion period for each cylinder. to erase. In this example, the integration circuit for each cylinder
The data from 30 are stored in the map A (n, 300) for 300 pieces.

Next, the controller 22 is stored in a predetermined storage location for the cylinder at the output or map the latest knock intensity I _F A of the integrating circuit 30 (n, 300). Next, the controller 22 obtains the average value A of the stored knock strength I _F of the cylinder. Then, this average value A is multiplied by a constant correction coefficient K _F to calculate a knock determination comparison level S _Fn in the combustion period of the cylinder.

Next, the controller 22 corrects the knock determination comparison level S _Fn in the combustion period of the cylinder and updates the correction coefficient D _n for obtaining the knock determination comparison level S _N in the non-combustion period.

In this case, in this example, in order to obtain the knock determination comparison level S _N in the reliable non-combustion period, whether or not knocking occurs is monitored, and the counter C _T is used to determine whether knocking does not occur for a certain period. The correction coefficient D _n is updated only when the operating state of the engine 1 is a steady state. That is, when knocking occurs, the counter C _T is set to 300, and when knocking does not occur, the counter C _T is decremented by 1 to obtain the counter C _T.
Becomes 0 and the flag F _A = 0, the ratio E _{n for the first time} to obtain the ratio E _n between the knock determination comparison level S _Fn in the combustion period and the knock determination comparison level S _{N in the} non-combustion period The correction coefficient D _n is updated by multiplying the current correction coefficient D _n .

Next, a procedure for obtaining the knock determination comparison level S _N in the specific combustion period and a procedure for _obtaining the output value S _OUT of the comparison level facing the comparator 25 will be described with reference to FIG.

In Figure 11, controller 22, non-combustion obtained in non-signal representative of the knock intensity of the combustion period I _N, a constant correction factor K _m, O _m and routines of the ninth diagram is output from the integrating circuit 30 Using the correction coefficient D _n between the knock determination comparison level S _N of the period and the knock determination comparison level S _Fn of the combustion period, the knock determination comparison level S _N of the non-combustion period is set to S _N = (K _m × I _N +
It is given as O _m ) × D _n . Since the knock determination comparison level S _N obtained in this routine is required for the cylinder to be subjected to the expansion stroke next, the coefficients K _m , O _m and D _n used to obtain this comparison level S _N are The value corresponding to the cylinder which performs the expansion stroke next is used for each.

Since knocking occurs when the cylinder is in the combustion state, it is desirable to make a determination using the knock determination comparison level of the combustion period in order to accurately determine whether knocking has occurred. However, when the engine is in a transient state such as during acceleration, the vibration level due to combustion changes, and it becomes difficult to set the knock determination comparison level for an appropriate combustion period.

In view of such circumstances, in the present example, in setting the knock determination comparison level, the controller 22 outputs to the comparator 25 depending on whether the operating state is a steady state or a transient state such as acceleration. Set the proper knock judgment comparison level output value S _OUT . During transient operation in which the combustion vibration level of the engine changes, that is, when the flag F _A is 1, the controller 22 sets the knock determination comparison level S _N in the non-combustion period as the output value S _OUT . Further, when the engine is in steady operation, that is, when the flag F _A is not 1, the controller 22 sets the knock determination comparison level S _Fn in the combustion period as the output value S _OUT .

Next, a procedure for _obtaining the knock correction advance angle Θ _Kn of the ignition timing will be described with reference to FIG.

In this example, the vibration generated in each cylinder is detected by using the single knock sensor 20, and knocking is detected by comparing the knock determination comparison level S _Fn and the vibration detection value set for each cylinder in advance, and the value is constant. The knocking occurrence status of the period is examined, the averaging process is performed to determine the knocking strength within that period, and the ignition timing control is performed for each cylinder based on this result, whereby knock control is performed. There is. Therefore, the knock sensor 20 must distinguish the input engine vibration signal and judge knocking for each cylinder.

However, in this configuration, since the positional relationship with the knock sensor 20 differs depending on the cylinder, the level of the signal indicating the engine vibration input to the knock sensor 20 differs depending on the cylinder.

In this embodiment, in view of these circumstances, the average sets the knock determination comparison level S _Fn for each cylinder, i.e. determination cycle J _n for determining knocking for each cylinder, a knock intensity generated separately The period for calculating the knocking strength for the ignition timing control by changing the processing is changed according to the cylinder.

In this case, in this example, the determination cycle J _n is set to be longer as the detection sensitivity of the knock sensor 20 becomes lower, for example, as the cylinder is farther from the knock sensor 20.

Further, in this example, learning control for the knock correction advance angle Θ _Kn is also performed, and the cycle R _n for updating this learning value is also the same as the knock determination cycle J _n of the knock sensor 20. The cylinders with lower detection sensitivity are made longer.

Next, the controller 22 determines whether or not the operating region is in the feedback region for performing knock control, and if it is not in the feedback region, the ignition timing is not corrected by the knock correction advance angle Θ _Kn. Therefore, in this example, the value of the knock correction advance angle Θ _Kn and other parameters are cleared.

If it is in the feedback area, the controller 22 determines a zone configured by subdividing the feedback area. Then, when the zone is the same as when the present routine was executed last time, the knock correction advance angle Θ _Kn stored as the learning value is adopted as the knock correction advance angle Θ _Kn to be used for the control.

Next, the controller 22 determines from the output value of the integrating circuit 30 whether knocking has occurred.

When knocking occurs, the controller 22 stores each knocking intensity I _K in a predetermined memory location B (n, C _En ) corresponding to the cylinder and determines the value of the flag F _B. , It is determined whether the knocking is the first knocking in the knocking determination cycle.

And if the knock is the first one,
Controller 22 depending on the value of the knock intensity I _K, determines the determination period L _n for determining the average level of the knocking intensity I _K.

In this case, when the determination cycle L _n is once determined, it is not preferable to change the cycle L _n during the determination period, so the flag F _B is set to 1 so that the determination cycle does not change. There is.

Then, the counter C _En determination period plus one counter C _En
This routine is repeatedly executed until L _n is reached. When knocking does not occur during the determination period, 0 is stored in the predetermined storage location B (n, C _En ).

However, in the knock determination operation described above, when the knocking strength I _K is large, it is desirable to perform prompt knock control regardless of whether the determination period is in progress. When the knocking intensity larger than the knocking strength I _K detected at the beginning of the determination period occurs, the determination work is immediately stopped and the knock correction advance angle Θ _Kn is calculated. That is, in the place where the first knocking strength B (n, 0) is larger than the detected knocking strength I _K , the counter C at that time is
The value of _En is put in the value of the cycle L _n to change the cycle.

Then, the controller 22 obtains the average value of the knocking strength I _K stored in the memory location B (n, C _En-1 ) when the predetermined determination period has elapsed. In addition, the controller 22
Calculates an ignition timing correction amount Θ _K according to the determined average knocking strength I _K.

Next, the controller 22 corrects the current knock correction advance angle Θ _Kn by the correction amount Θ _K to obtain a new knock correction advance angle Θ _Kn.
Set _Kn .

Further, in this case, the controller 22 is the counter C _En ,
Clear flag F _B.

Further, in the ignition timing control of the cylinder, it is desirable to keep the ignition timing appropriate by making the retard amount as small as possible unless an abnormality such as knocking occurs. From this point of view, in this example, if knocking does not continue for a certain period of time, the knocking correction advance angle Θ _Kn is corrected to be small.
That is, when the knocking using a counter C _En does not occur, if the counter C _En by the counter C _En to be added each time reaches a predetermined value J _n × K _J is set for each cylinder, the current knock Corrected advance angle Θ _Kn to predetermined value Δ
Θ is subtracted to set a new knock correction advance angle Θ _Kn .

Further, the controller 22 stores the knock correction advance angle Θ _Kn newly set in the above procedure in the map for learning value calculation.
Then, if the learning value update conditions such as whether the operation state is steady, the operation state of the same zone continues for a predetermined time, and the learning value update period R _n has passed, the learning value of the zone is satisfied. Update Θ _GnMAP .

Next, the procedure for obtaining the ignition advance angle Θ _Ig for giving the final ignition timing will be described with reference to the flowchart of the ignition timing control routine shown in FIG.

Referring to FIG. 10, the controller 22 first determines from the read various data whether or not the engine 1 is in the starting state, and if it is in the starting state, sets the ignition timing to a predetermined constant value. . Next, the controller 22 determines whether the engine is in the idle state, and when it is in the idle state, calculates the idle advance angle Θ _IDL and sets it as the ignition advance angle Θ _Ig . Further, in an operating state that is neither the start-up nor the idle state, that is, in the normal operating state, the controller 22 determines the basic advance angle Θ _BASE using a map based on the engine speed N _e and the intake air amount Q _a. To do. In this case, the controller 22 further calculates the water temperature correction advance angle Θ _{WT of the} ignition timing based on the signal from the water temperature sensor 19 and the intake air temperature correction advance angle Θ _{A based} on the signal from the intake temperature sensor 11a.

Next, the controller 22 reads out the knock correction advance angle Θ _Kn obtained by executing the interrupt routine shown in the flowcharts of FIGS. 6 and 7.

Further, the controller 22 calculates the acceleration correction advance angle Θ _ACC for performing the advance angle correction in the acceleration state, and at the same time calculates the various advance angle correction values obtained in the above procedure to obtain the final ignition advance value. Ignition advance angle Θ _Ig that should be output as Θ _Ig = Θ _BASE +
It is given as Θ _AT + Θ _WT − Θ _Kn − Θ _ACC .

Then, the controller 22 stores the finally obtained ignition advance value Θ _Ig in a predetermined internal counter until the ignition timing of the cylinder.

As described above, according to the control of the present example, in calculating the knocking strength I _K of each cylinder obtained by the averaging process for the fixed period, the knock determination period is set according to the sensitivity of the signal in the knock sensor 20. Therefore, it is possible to more appropriately determine the knocking strength. Therefore, in the engine of this example, the ignition advance angle Θ _Ig for each cylinder can be appropriately calculated using the single knock sensor 20, and as a result, accurate knock control by ignition timing control can be performed. .

In this example, the case where the ignition timing is controlled to perform knock control has been described, but the present invention is not limited to the ignition timing,
The present invention can be similarly applied to arbitrary control performed for factors that affect the operating state effective for suppressing knocking, such as the air-fuel ratio and EGR amount.

[Brief description of drawings]

FIG. 1 is an overall schematic diagram of an engine according to an embodiment of the present invention, FIG. 2 is a detailed diagram of a knock detection circuit, FIG. 3 is a background routine flowchart, and FIG. 4 is a transient determination flag setting routine flowchart. FIG. 5 is a flowchart of an interrupt routine executed when a cylinder identification signal is input, FIG. 6 is a flowchart of an interrupt routine executed when a crank signal is input, and FIG. 7 is correspondence of various signals. A time chart showing the relationship, FIG. 8 is a flowchart of a subroutine for calculating knock intensity determination and knock correction advance angle, FIG. 9 is a flowchart of a subroutine for obtaining a knock determination comparison determination level in the combustion period, and FIG. 10 is ignition advance. FIG. 11 is a flowchart of a subroutine for calculating the angle, and FIG. 7 is a flowchart of a subroutine for calculating a comparison determination level output value to a knock detection circuit. 1 ... Engine, 2 ... Cylinder block, 3 ... Piston, 4 ... Combustion chamber, 5 ... Intake port, 6 ... Exhaust port, 7 ... Intake valve, 8 ... Exhaust valve, 9 ... Intake aisle,
10 …… Air cleaner, 11 …… Air flow meter, 12
...... Throttle valve, 13 ...... Surge tank, 14 …… Injector, 15 …… Exhaust passage, 16 …… Spark plug, 20 ……
Knock sensor, 21 …… Crank angle sensor, 22 …… Controller, 23 …… Knock detection circuit, 24 …… Band pass filter, 25 …… Comparator, 26,27 …… Switch, 28,29 ……
Half-wave rectification integrator circuit, 30 ... Integrator circuit.

Claims (1)

[Claims] 1. A vibration detecting means for detecting engine vibration,
A first reference creating unit that receives an output from the vibration detecting unit and creates a first reference value from a vibration level in an engine combustion period, and a second reference value from an output of the vibration detecting unit from a vibration level in an engine non-combustion period Second reference value creating means for creating a reference value for the engine, an operating state detecting means for detecting an operating state of the engine, and an output from the operating state detecting means. The first comparing means for comparing the output with the first reference value to determine knocking and the output from the operating state detecting means receive the output from the vibration detecting means and the first comparing means during the acceleration operation of the engine. Second comparing means for comparing knocking by comparing with a reference value of 2, and selecting the first or second reference value according to an operating state and comparing with a signal from the vibration detecting means. The second reference value is increased based on the first reference value created during the steady operation, and the second reference value is increased in the direction of increasing the second reference value. An engine knocking detection device characterized by correction.