JPH0742926B2 - Engine ignition timing control device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine ignition timing control device that detects engine knocking and controls ignition timing so as to suppress knocking.

(Prior Art) An engine is known that includes a knock sensor for detecting a knocking state of the engine, and controls the ignition timing of the engine based on a signal from the knock sensor to suppress knocking.

For example, Japanese Patent Application Laid-Open No. 58-28597 discloses a control device that suppresses knocking by controlling such ignition timing. In this disclosed device, the engine is equipped with a vibration detection element for detecting vibration, and the average value of the amplitude values of the electric signal from this vibration detection 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.

(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. However, if the ignition timing is controlled so as to be delayed in order to suppress knocking as described above, there is a problem that the engine torque decreases. Therefore, from the viewpoint of torque performance, it is desirable to reduce the retard amount from the optimum ignition timing as much as possible.

Therefore, in this kind of knocking control device, when knocking occurs, the ignition timing is retarded by a predetermined amount, and when knocking does not occur, feedback control of the ignition timing that advances the ignition timing so as to approach the optimum ignition timing. Is supposed to do. However, the influence of the ignition timing on the torque performance is not uniform, and the amount of torque drop tends to increase as the retard amount increases. If the feedback control amount of the ignition timing is reduced in order to reduce the torque fluctuation, there is a problem that the responsiveness of knocking control deteriorates and it becomes impossible to effectively suppress knocking.

(Means for Solving the Problems) The present invention is configured in view of the above circumstances, and is capable of effectively suppressing knocking with good responsiveness, and
An object of the present invention is to provide an engine ignition timing control device capable of minimizing torque fluctuations caused by ignition timing control for suppressing knocking.

The ignition timing control device of the present invention is based on knocking detection means for detecting knocking and a signal from the knocking detection means. When knocking occurs, the ignition timing is retarded, and in an operating state where knocking does not occur. In an ignition timing control device for an engine that performs feedback control of the ignition timing so as to advance the ignition timing, the feedback control amount of the ignition timing is decreased in response to an increase in the ignition timing retarding amount due to the knocking. It is characterized by being configured as follows.

According to the present invention, when performing the feedback control of the ignition timing for suppressing the knocking, the feedback control amount is set in consideration of the influence of the retard amount of the ignition timing on the torque performance. That is, the feedback control amount is set to be relatively large in the vicinity of the optimum ignition timing where the influence of the change in the ignition timing on the torque performance is relatively small, and the control amount is reduced as the retard amount from the optimum ignition timing increases. To control.

(Effect of the Invention) According to the present invention, since the feedback control amount of the ignition timing is set to be relatively large near the optimum ignition timing, knocking can be suppressed with good responsiveness. In this region, the change of the ignition timing does not significantly affect the torque performance, so that there is no fear that a large torque fluctuation will occur. Then, as the retard amount from the optimum ignition timing increases,
Since the feedback control amount is controlled to be small, it is possible to reduce the torque fluctuation caused by the knocking control in the state where the retard amount is large. Therefore, according to the present invention, knocking can be effectively suppressed, and torque fluctuations due to ignition timing control for suppressing knocking can be suppressed as much as possible.

(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 sensor 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 that detects the intake air temperature is attached to the air flow sensor 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 plug 16.

Further, a water temperature sensor 19 for detecting a cooling water temperature is attached to a water jacket 18 formed in the cylinder 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 the present example, a signal for identifying the cylinder can be 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. Referring also to FIG. 2, the controller 22 receives signals representing the intake air amount and the intake air temperature from the air flow sensor 11 and the intake air temperature sensor 11a, 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. As for the 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 controller 22, the signal that has passed through the bandpass filter 24 is directly input to the comparator 25 on the one hand, and on the other hand, is input to the circuit 23 that creates a reference level for knocking determination. It The signal from the comparator 25 is input to the knock determination circuit 26 to determine knocking. Then, the signal from the knock determination circuit 26 is
It is input to the cylinder determination circuit 27 and the circuit in which the knocking signal is generated is specified. The controller 22 is provided with means for calculating the ignition timing retard amount Θ _K for each cylinder.
In this case, the knocking signal for each cylinder from the cylinder discriminating circuit 27 is input to the average retardation amount calculation circuit 28 provided for each cylinder, and the average value of the knocking signals within a predetermined time range
▼, ▲ ▼, ▲ ▼, and ▲ ▼ are calculated. Then, the signal from the average retardation amount calculation circuit 28 is input to the retardation amount calculation circuit 29 for calculating the ignition timing retardation amounts Θ _K1 , Θ _K2 , Θ _K3 , and _K4 provided for each cylinder. It

Further, the signal from the water temperature sensor 19 is input to the circuit 30 which calculates the correction value Θ _WT of the retard angle amount according to the water temperature. Further, the signal from the intake air temperature sensor 11a is a correction value Θ _AT according to the intake air temperature.
Is input to the circuit 31 for calculating Further, the signals from the air flow sensor 11 or the throttle valve opening sensor 12a and the crank angle sensor 21 are input to the memory 32 and the memory 32 receives the signals.
The basic retardation amount Θ _BASE is calculated from the map stored in 32.

The controller 22 calculates a final ignition timing Θ _IG by performing a predetermined calculation based on these calculated retard amounts, and inputs this value to the ignition signal generation circuit 33. Then, when the ignition timing of the cylinder comes, an ignition signal is output to the igniter 34.

The control of this example will be described below.

FIG. 3 shows a flowchart of the ignition timing control routine.

Referring to FIG. 3, the controller 22 first initializes the system, determines from the various read data whether the engine 1 is in the starting state, and if it is in the starting state, sets the ignition timing. Hard ignition is performed by setting a predetermined constant value. When the engine is not started, the ignition timing is switched to soft ignition which is determined based on the calculated 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 the operating state that is not at the time of starting and is not in the idle state, that is, in the normal operating state, the controller 22 is
The basic advance angle Θ _BASE is determined using a map based on the engine speed N _e and the intake air amount Q _a . And the controller
22 further calculates a water temperature correction advance angle Θ _{WT of the} ignition timing based on the signal from the water temperature sensor 19 and an intake air temperature correction advance angle Θ _AT from the signal from the intake noise sensor 11a.

Next, the controller 22 executes the subroutine shown in the flowchart of FIG. 4 to calculate the knock correction advance angle Θ _Kn .

Referring to FIG. 4, the controller 22 determines the cylinder N and reads the knocking strength I _K. Next, the controller 22 determines the operating state to determine whether it is in the knocking control region, and when it is not in the knocking control region, knocking control based on the ignition timing of this example is not performed. When the knocking has occurred, in accordance with the knock intensity I _K that its occurrence, the retard amount Θ
Calculate _R. Next, the controller 22 calculates the correction value K _R according to the value of the retard angle amount Θ _R. In this case, the correction value K _R is stored in a predetermined memory as a map of a function of the retard amount theta _R, is set to be smaller larger the retard amount theta _R increases.

Next, the controller 22 determines the current knock correction advance angle Θ _Kn.
A new knock correction advance angle Θ _Kn is calculated only when is _smaller than or equal to the preset maximum knock correction advance angle Θ _Kmax . That is, in the control of this example, the knock correction advance angle Θ _Kn is limited so as to minimize the adverse effect on the torque performance.

Then, the controller 22 corrects the current knock correction advance angle Θ _Kn and calculates a new knock correction advance angle Θ _Kn = Θ _kn + Θ _R × K _R.

If knocking has not occurred, the controller 22 determines the current value of the knock correction advance angle Θ _Kn , and if the value of the correction advance angle Θ _kn is positive, decreases the retard amount. The correction value K _A for is read from the map. The correction value K _A is given as a function of the average knock correction advance angle, and is set so as to decrease as the knock correction advance angle increases.

Next, the controller 22 determines the current knock correction advance angle Θ _Kn.
The new knock correction advance angle Θ _Kn = Θ _kn − Θ
Calculate _A x K _A. In this case, the advance amount Θ _A is the ignition timing correction amount when knocking does not occur. As described above, in the control of the present example, when knocking does not occur, the retard amount is gradually decreased to control the ignition timing to approach the optimum ignition timing, and the control amount is retarded. The larger the angular amount, the smaller the angular amount, so that large torque fluctuations do not occur.

Through the above processing, the calculation of the knocking control subroutine is completed, and the controller 22 continues the processing of the routine of FIG. 3 again.

Next, in FIG. 3, the controller 22 calculates the ignition advance angle Θ _Ig to be output as the final ignition advance value by calculating the various advance angle correction values obtained in the above procedure, and Θ _Ig = Θ _BASE + Θ _AT
+ Θ _WT −Θ _Kn

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.

According to the control of this example described above, the ignition timing is controlled so as to approach the optimum ignition timing as much as possible, and when knocking occurs, a predetermined retard control of the ignition timing is performed, It is designed to effectively suppress knocking. In this case, the relationship between the ignition timing and the torque fluctuation is
As shown in FIG. 5, the retard amount from the optimum ignition timing, or
As the amount of advance angle increases, the tendency for the torque to decrease becomes more pronounced. Therefore, if control is performed with the same retard angle control amount Θ _K simply in response to the occurrence of knocking, in a driving state with a large retard angle amount, as shown in the figure, the torque change ΔT ₂ is a driving amount with a small retard angle amount. The torque change becomes larger than the torque change ΔT ₁ in the state, the occupant's discomfort increases, and the output performance is not preferable. In view of this point, in the control of the present example, as described above, the control amount of the ignition timing is decreased as the offset amount from the optimum ignition timing increases. This minimizes torque fluctuations,
Knocking can be effectively suppressed.

[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 block diagram of a controller, FIG. 3 is a flowchart of an ignition timing control routine, FIG. 4 is a flowchart of a knocking control subroutine, and a fifth flowchart. The figure is a graph showing the relationship between ignition timing and torque change. 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, 24 …… bandpass filter, 25 …… comparator, 34
...... Igniter.

Claims (1)

[Claims] 1. A knocking detection means for detecting knocking, and based on a signal from the knocking detection means, retards the ignition timing when knocking occurs, and in an operating state in which knocking does not occur, sets ignition timing. In an ignition timing control device for an engine that performs feedback control of ignition timing so as to advance, it is configured to decrease the feedback control amount of the ignition timing in response to an increase in the ignition timing retarding amount due to the knocking. An engine ignition timing control device characterized by the above.