JP2629204B2 - Ignition timing control device for internal combustion engine - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an ignition timing control device for an internal combustion engine,
The ignition timing learning control is performed by newly setting the lower limit of the retard amount based on the knock generation point for each operation region in a certain operating state of the engine and giving a learning value common to all operation regions based on this point. The present invention relates to an ignition timing control device for an internal combustion engine.

2. Description of the Related Art Conventionally, in an ignition timing control device with a knocking control device in an electronically controlled internal combustion engine, an ignition timing corresponding to a rotation speed and an engine load is calculated by an electronic advance angle system. When ignition occurs, the ignition timing is retarded by a signal from a knock sensor. That is, when knock is detected, the ignition timing is retarded by a certain angle until knock is no longer generated. The retard amount is not unlimited, the maximum retard amount is determined by the engine speed and the engine load, and the retard amount by the knock control device is between the basic ignition timing and the ignition timing determined by the maximum retard amount. moving. Then, when knock does not occur, the ignition timing control device advances the ignition timing. When knocking occurs again after the advance, retard correction is performed in the same manner as described above.

[Problems to be solved by the invention]

However, in the conventional ignition timing control device, when the basic ignition timing is set under the condition that knock is hardly generated in a case where a wide range of fuel octane numbers and environmental conditions are supported,
Conversely, when knock is most likely to occur, an excessive knock always occurs at the moment when the operating state of the engine shifts to the operating region where knock occurs. This is because in the conventional ignition timing control device, the ignition timing is not retarded unless knock occurs.Since the knock control device does not operate at the moment when the engine load suddenly changes for the first time, an excessive knock is generated. It happens.

To prevent this, JP-A-55-78168 and JP-A-5-78168
As disclosed in JP-A-9-103945, there is an ignition timing control device incorporating learning control. The ignition timing control device incorporating the learning control has a learning value for each of a plurality of operating regions, and stores the ignition timing at which knock occurred once in the region as a learning value. When the condition enters the range, the ignition timing is controlled based on the learned value.

However, even in the conventional ignition timing control device introducing the learning value, the learning value is updated based on the basic ignition timing, and the learning value is not updated unless the operation range is reached, Less frequent learning,
There is a problem that excessive knock is generated when the operation state is first shifted from a certain operation state to a certain operation state.

The present invention solves the above-mentioned conventional problems, performs learning control by determining a learning value that takes only one value in a conventional learning region based on the ignition timing in a state where knock is likely to occur in the engine, and The update of the learning value is performed in the same manner over the entire operating range of the engine regardless of the progress of the operating state, thereby preventing an excessive retardation and an excessive knock when the operating state of the engine suddenly changes. An object is to provide an ignition timing control device.

[Means for solving the problem]

FIG. 1 shows a configuration of an ignition timing control device for an internal combustion engine according to the present invention which solves the above problems.

An ignition timing control device according to the present invention includes a knocking detection unit that detects knocking occurring in an engine, a basic ignition timing calculation unit that calculates a basic ignition timing according to an operation state of the engine, and A delay amount lower limit value calculating means for calculating a predetermined retard amount lower limit value; and a retard correction amount for advancing the ignition timing when knocking does not occur and the ignition timing is retarded when knocking does not occur. Means for calculating a retardation correction amount for calculating, and a retardation amount for calculating an instantaneous lower limit value of a retardation amount based on a lower limit value of a retardation amount and a learning value defined as a single value in a learning area for correcting the same. An instantaneous lower limit value calculating means, a learning value updating means for updating a learning value such that a difference between the retardation correction amount and the retardation amount instantaneous lower limit value falls within a predetermined range in a predetermined operation region, and a retardation correction amount. Retardation amount limited by instantaneous lower limit of retardation amount And control means, the retard correction amount limited by the retard correction amount limiting means, characterized in that they are composed of the ignition timing correction means for controlling a correction to the ignition timing to the basic ignition timing.

[Action]

According to the ignition timing control apparatus for an internal combustion engine of the present invention, a new instantaneous lower limit of the retard amount is newly created by a learning value common to all operation regions with reference to a predetermined lower limit of the retard amount, and the engine is knocked. Even when the operating state shifts from the hardly occurring state to any operating state in which knock is likely to occur, the retard amount from the basic ignition timing is instantaneously corrected by the retard amount instantaneous lower limit value.

〔Example〕

 Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 2 schematically shows an entire configuration of an embodiment of an ignition timing control device for an internal combustion engine according to the present invention.

In FIG. 2, 10 is a cylinder block of the engine, and 12 is a knock sensor attached to the cylinder block 10. Knock sensor 12 is formed of, for example, a piezoelectric element or an electromagnetic element, and is a known sensor that converts mechanical vibration into electrical amplitude fluctuation. Reference numeral 14 denotes a distributor. The distributor 14 is provided with crank angle sensors 16 and 18. The crank angle sensor 16 is for cylinder discrimination. If this engine has six cylinders, one pulse is generated each time the distributor shaft makes one rotation, that is, every two rotations of the crankshaft (every 720 ° CA). . The occurrence position is set, for example, like the top dead center of the first cylinder. The crank angle sensor 18 generates 24 pulses each time the distributor shaft makes one rotation, that is, generates a pulse every 30 degrees of the crank angle.

Electric signals from knock sensor 12 and crank angle sensors 16 and 18 are sent to control circuit 20. A signal representing the amount of intake air from an air flow meter 24 provided in an intake passage 22 of the engine is also sent to the control circuit 20. On the other hand, an ignition signal is output from the control circuit 20 to the igniter 26, and the spark current generated by the igniter 26 is distributed to the ignition plug 28 of each cylinder via the distributor 14.

The engine is usually provided with various other sensors for detecting operating state parameters, and the control circuit 20 also controls the fuel injection valve 30 and the like, but since these are not directly related to the present invention, These are all omitted in the following description.

The electric signal from the air flow meter 24 is sent to an analog multiplexer (MPX) 32 via a buffer 30,
A / is selected according to the instruction from the microcomputer.
After being applied to the D converter 34 and converted into a binary signal, it is taken into the microcomputer via the input / output port 36.

A pulse at every crank angle of 720 ° from the crank angle sensor 16 is applied to the interrupt request signal generation circuit 40 via the buffer 38. On the other hand, the crank angle from the crank angle sensor 18
The pulse every 30 ° is applied to the interrupt request signal generation circuit 40 and the speed signal generation circuit 44 via the buffer 42. The interrupt request signal generation circuit 40 generates various interrupt request signals from each pulse every 720 ° and every 30 ° of the crank angle. These interrupt request signals are applied to the microcomputer via the input / output port 46. The speed signal generating circuit 44 determines the engine speed Ne from the cycle of the pulse at every 30 ° crank angle.
Make a hexadecimal signal. This rotation speed signal is sent to the microcomputer via the input / output port 46.

The output signal of the knock sensor 12 is sent to the peak hold circuit 50 through a buffer for impedance conversion and a buffer / filter circuit 48 including a band-pass filter whose pass band is a knock-specific frequency band (7 to 8 kHz). The peak hold circuit 50 has an input / output port 46 and a line 52.
Only when a "1" level signal is applied from the microcomputer via the microcomputer, the output signal from the knock sensor 12 is taken in and the hold operation of the maximum amplitude is performed. A reset signal is input via the input / output port 46 and the line 70, and the maximum amplitude is reset. The output of the peak hold circuit 50 is converted into a binary signal by the A / D converter 54 and sent to the microcomputer via the input / output port 46.
However, A / D conversion of the A / D converter 54 is started by an A / D converter applied from the microcomputer via the input / output port 46 and the line 56.
This is performed by the D conversion start signal. When the A / D conversion is completed, the A / D converter 54 notifies the microcomputer of the completion of the A / D conversion via the line 58 and the input / output port 46.

On the other hand, when an ignition signal is output from the microcomputer to the drive circuit 60 via the input / output port 46, the signal is converted into a drive signal, the igniter 26 is energized, and the igniter 26 is activated according to the duration and the duration of the ignition signal. Ignition control is performed.

The microcomputer uses the input / output ports 36 and 46 described above.
And a microprocessor (MPU) 62, a random access memory (RAM) 64, a read only memory (ROM) 66, a backup random access memory (B-RAM) 69 that retains the stored contents even when the power is turned off, not shown. Clock generation circuit, memory control circuit, and bus connecting these
It mainly comprises 68 and the like, and executes various processes according to a control program stored in the ROM 66.

The ROM 66 contains a map of the basic ignition timing ABSE expressed by the engine speed and the engine load, and a knock limit value (1 to 3) slightly smaller than the knock limit value according to the engine speed and the engine load when using regular gasoline. A map of the advanced retard amount is stored in advance.

Next, the operation of the control circuit 20 of FIG. 2 will be described.
FIG. 3 shows an interrupt routine executed at every 90 ° CA of BTDC before the top dead center of each cylinder.

In step 301, first, the engine speed Ne and the engine load Q / N
(In this embodiment, the intake air amount per one rotation of the engine is adopted as the engine load.) Then step
The basic ignition timing ABSE corresponding to the engine speed Ne and the engine load Q / Ne read in 302 is calculated using the above-mentioned map. The basic ignition timing ABSE is shown by a solid line in the ignition timing-torque characteristic diagram of FIG. Then, in step 303, the retard amount upper limit value AKCS _max , the retard amount instantaneous upper limit value tAKCS _max ,
The lower limit of the amount of retardation AKCS _min and the instantaneous lower limit of the amount of delay tAKCS
Calculate _min . Note that AKCS _max and AKCS _min are
0 and stored in ROM66, tAKCS _max and tAKCS _min
It is stored in RAM64.

The retard amount upper limit value AKCS _max is a maximum retard amount that is meaningless even if the ignition timing is further retarded. Instantaneous upper limit value of retard amount tAKC
Smax is a retard amount upper limit AKCSmax corrected (advanced) by a learning value AGKCS described later, and is calculated by the following equation after engine operation.

tAKCSmax = AKCSmax−AGKCS... At first, since AGKCS is 0, tAKCSmax = AKCSmax. However, after the institution enters the learning area even once, AGKCS
Initial value (AGKCS used first after entering the learning area)
Is the AGKCS that was last learned last time.

The lower limit of the retard amount AKCS _min is newly set in the present invention, and is slightly (about 1 to 3 °) smaller than the knock limit value depending on the engine speed and the engine load when regular gasoline is used. This is the amount of retardation advanced. The instantaneous lower limit value tAKCS _min of the retard amount is the upper instantaneous value tAKCS _{max of the} retard amount.
Similarly, the lower limit of the amount of retardation AKCS _min is learned and corrected using the following equation: tAKCS _min = AKCS _min -AGKCS.
Similarly to the above-mentioned retard instantaneous upper limit value tAKCS _max , initially tAKCS _min =
AKCS _min , but after the institution enters the learning area even once, the initial value of AGKCS (the first used AGKCS in the learning area) is the last and last learned AGKCS.

When step 303 ends, the process proceeds to step 304, where it is determined whether the tAKCS _min value is a positive value or a negative value. tAKCS
_{If the min} value is a positive value (YES), the process proceeds to step 306, but t
When the AKCS _min value is a negative value (NO), the process proceeds to step 305 and tA
Reset the KCS _min value to 0. This is because the basic ignition timing ABSE is the maximum torque point and it is useless to advance the angle beyond this value, so the lower limit value is set to 0.

In step 308, the retard correction amount (hereinafter, referred to as knock control retard amount) AKCS is updated. The details of this update are shown in FIG. This update is performed every 120 ° CA (top dead center TDC). Knocking occurs at the top dead center TD of the stroke of a certain cylinder
This is performed when knock has occurred between C and the next top dead center TDC (step 401). Only when knock has occurred (YES), in step 402, the knock control retard amount AKCS is set to the angle α ( CA).
Then, after the retard processing is performed in step 402, the count value of the counter is cleared in step 403, and the process returns. The update of the knock control retard amount AKCS is also performed every predetermined time during which no knock occurs. At this time, in step 404, the count value of the counter is set to a predetermined time, for example, 0.4
It is determined whether or not sec has been exceeded, and after a predetermined time has elapsed, as shown in step 405, knock control retard amount AKCS is advanced by angle β (CA). And step 40
After returning the count value of the counter to 0 at 6, the program returns.

In step 309, the knock control retard amount AKCS updated as described above is used to calculate the retard amount instant upper limit value tAKCS _max and the retard amount instant lower limit value tAKC calculated in step 303.
Guard at S _{min so} that the knock control retard amount AKCS falls within this range. As described above, at the initial stage after the start of the engine operation, at the stage where the learning control is not yet performed, tAKCS _max = AKCS _max and tAKCS _min = AKCS _min. Value AKCS
It is first guarded by _max and the retard amount lower limit AKCS _min .

Step 310 is for updating the learning value AGKCS for correcting the upper and lower limit values of the retard amount.
Shown in the figure. The learning value AGKCS is stored in the B-RAM 69 of the control circuit 20.
Is stored in

Steps 501 and 502 are for determining whether or not the operating state of the engine is in a knock control learning control execution region.
The engine speed Ne is within a range between the predetermined speeds x and y, for example, 100 r
When it is within the range from pm to 6000 rpm, and when the retard amount upper limit AKCS _max is equal to or greater than the predetermined crank angle z (for example, 10 ° CA), it is considered that the learning control execution region of the knock control is executed. In other cases, the learning value AGKCS is guarded from 0 to AGKCS _max in step 507.

In the following step 503, knock control retard amount AKCS
Is compared with the instantaneous lower limit value of the retardation amount tAKCS _min . If the difference is smaller than a (for example, 2 to 4 ° CA) (YES), the process proceeds to step 504, and the learning value AGKCS is changed by p (for example, 0.1 to 1 ° CA). to add. As a result, the range tAKCS _{min to} tAKCS _max of the knock control retard amount AKCS moves by p toward the advance side. In step 505, the knock control retard amount AKCS is compared with the retard amount instantaneous lower limit value tAKCS _min, and the difference is b (for example, 4 to 6).
° CA) or more (YES), the process proceeds to step 506, where the learning value AG
Subtract q (for example, 0.1 to 1 ° CA) from KCS. Thus, the range of the knock control retard amount AKCS is tAKCS _min ~
tAKCS _max moves by q to the retard side. Step 507 is the guard of the learning value AGKCS, 0 from AGKCS _max (e.g. 7
~ 10 ° CA).

By the above control, the knock control retard amount AKCS is always within the range of a to b on the retard side from the retard amount instantaneous lower limit value tAKCS _min .

When the update of the learning value AGKCS in step 310 is completed, the process proceeds to step 311 in which the ignition timing correction calculation is performed by using the expression (ABSE
-AKCS), and the spark plug 28 sparks at the corrected ignition timing.

Next, the operation of the ignition timing control device for an internal combustion engine of the present invention described above will be described with reference to FIG.

FIG. 6 shows ignition timing and torque characteristics in a certain rotation range of the engine for each engine load. When the operating state of the engine enters the learning region from outside the learning region, the retard amount AKCS from the basic ignition timing ABSE obtained in step 308
Is instantaneously guarded to the lower limit of the retard amount instantaneous lower limit value AKCS _min . The retard amount instantaneous lower limit value tARCS _min is set on the a-b advance angle side from the last and last obtained AKCS.

After that, the retard amount AKCS is updated according to the occurrence of knock,
When the knock does not occur, the retard amount AKCS is reduced. When the difference from the instantaneous lower limit value AKCS _min of the retard amount becomes less than a, the learning AGKCS
Increases, and the retard amount lower limit instantaneous AKCS _min moves to the advance side. When a knock occurs, the retard amount AKCS is increased, and when the difference from the instantaneous lower limit value of the retard amount AKCS _min becomes b or more, the learning value A
GKCS decreases, and the instantaneous retardation lower limit value AKCS _min moves to the retard side.

As described above, in the device of the present invention, the knock control correction value AKCS is first limited in any operation region by the retardation amount instantaneous lower limit value tAKCS _min set for each region, and the retardation amount instantaneous lower limit value tAKCS _min The learning value AGKCS is updated so as to maintain a certain relationship with the learning value AGKCS. Then, the learning value A of the present invention
GKCS is a single value irrespective of the operating range of the engine through the conditions of the engine speed Ne and the engine load Q / Ne.

Therefore, as shown in the three-dimensional map of FIG. 7, the basic ignition timing ABSE is determined as shown by a solid line corresponding to the engine speed Ne and the engine load Q / Ne. When the upper limit value AKCS _max is set as shown by a broken line and the lower limit value AKCS _min is set as shown by an alternate long and short dash line, for example, the fuel is changed from regular gasoline to high-octane gasoline. When the deviation of the instantaneous lower limit value tAKCS _{min to} the advance side is calculated, the learning amount AGKCS is common, so the retardation amount instantaneous lower limit value tAKCS _min becomes the retardation lower limit value as shown by the two-dot chain line in FIG. It shifts in a plane parallel to the value AKCS _min . Therefore, no matter what kind of operation the engine that changes the fuel to high-octane gasoline thereafter performs the optimal ignition advance in each operation region, and does not generate excessive knock.

When this engine stops using high-octane gasoline and returns to using regular gasoline, if it is calculated in an operating region where the retardation amount instantaneous lower limit tAKCS _min is shifted to the retard side, the learning value AGKCS Since the retarding amount instantaneous lower limit value tAKCS _min is retarded throughout the entire operation range by the operation, excessive knock does not occur.

〔The invention's effect〕

As described above, according to the ignition timing control apparatus for an internal combustion engine of the present invention, the execution ignition timing at the moment when the operating state shifts to any operating region in which knock occurs is the retard angle calculated last in the previous learning region. Since it can always be set to the side advanced by a certain amount from the amount AKCS, there is an effect that excessive knock and excessive retard do not occur.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the configuration of an ignition timing control device for an internal combustion engine according to the present invention, FIG. 2 is a schematic configuration diagram of an engine equipped with the ignition timing control device for an internal combustion engine according to the present invention, and FIGS.
FIG. 2 is a flowchart showing the operation of the control device shown in FIG. 2, and FIG. 6 is an ignition timing chart for explaining the operation of the device of the present invention.
FIG. 7 is a three-dimensional map for explaining the operation of the device of the present invention. 10 ... engine cylinder block, 12 ... knock sensor,
14 ... Distributor, 16,17 ... Crank sensors, 20 ... Control circuit, 22 ... Intake passage, 24 ... Air flow meter, 28 ... Spark plug, 30 ... Fuel injection valve.

Claims (1)

(57) [Claims] 1. Knock detecting means for detecting knocking occurring in an engine; basic ignition timing calculating means for calculating a basic ignition timing in accordance with an operation state of the engine; and a predetermined delay in accordance with an operation state of the engine. A delay amount lower limit value calculating means for calculating an angular amount lower limit value, and a retard angle for calculating a retard correction amount for delaying the ignition timing when knocking occurs and advancing the ignition timing when knocking does not occur. Correction amount calculating means; and a retard amount instantaneous lower limit for calculating the retard amount instant lower limit value based on the retard amount lower limit value and a learning value defined as a single value in a learning area for correcting the retard amount lower limit value. Value calculation means; learning value updating means for updating the learning value such that a difference between the retardation correction amount and the instantaneous retardation lower limit value is within a predetermined range in a predetermined operation region; Correction amount is the instantaneous retard amount lower limit And an ignition timing correction means for controlling the ignition timing by correcting the basic ignition timing based on the retardation correction amount limited by the retardation correction amount restriction means. Engine ignition timing control device.