JP2551500B2 - Ignition timing control device for internal combustion engine - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ignition timing control device for an internal combustion engine, and more specifically to knock control with a plurality of types of ignition timing control characteristics according to the octane number of the fuel used. In particular, the present invention relates to an ignition timing control device for an internal combustion engine in which the characteristic is changed under a predetermined condition in order to remedy the selection of the control characteristic due to an erroneous determination.

(Prior Art) Recently, an engine that uses a high octane fuel is being provided in response to a demand for higher output. In such an engine, when a planned high octane fuel is used and other octane fuels are used. Since the ignition timing to be set is different from that when is used, the control characteristic of the ignition timing is separately established according to the octane number. Also, the fuel actually used does not always have the expected octane number, so the octane number of the used fuel is judged from the knocking occurrence state, and the ignition timing is controlled by selecting the control characteristic corresponding to it. There is. One example is JP-A-1-96473.
The technique described in the publication can be mentioned.

By the way, when a plurality of types of control characteristics are set as described above, there is a possibility that the octane value of the fuel is erroneously determined to be low and a characteristic on the retard side is selected, thereby unnecessarily reducing the engine output.
Therefore, it is necessary to temporarily cancel the characteristic selected under an appropriate operation state and return to the control characteristic on the advance side. From this point, the applicant has previously proposed in Japanese Patent Application No. 63-51268 (Japanese Patent Laid-Open No. 1-224468) that the selected control characteristic is advanced when a predetermined time elapses while the engine speed is below a predetermined value. We are proposing a technology to force a shift to the side.

(Problems to be Solved by the Invention) However, this method is effective when the control characteristic on the retard side is selected by mistakenly determining that the low octane fuel is used when the high octane fuel is used. When octane fuel is used and the control characteristic on the retard side is properly selected, if the high octane characteristic on the advance side is changed, knocking frequently occurs and the control hunting is returned to the low octane characteristic again. There is an inconvenience.

Therefore, an object of the present invention is to provide an ignition timing control device for an internal combustion engine, which eliminates the inconvenience and appropriately switches the ignition timing characteristics without causing control hunting.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides, for example, claim 1
As described in the section, engine operating state detecting means for detecting the operating state of the engine including at least engine speed and engine load, knock detecting means for detecting knock occurring in the engine, at least low octane fuel depending on the octane number of the fuel used. Ignition timing control characteristics for vehicles and second for high octane fuels
The ignition timing control characteristic setting means for setting the control characteristics of a plurality of types of ignition timing consisting of the ignition timing control characteristics, the engine operating state detection means, the knock detection means, and the output of the ignition timing control characteristic setting means are input, Ignition timing determining means for selecting the control characteristic corresponding to the octane number of the fuel used based on the generation state and determining the ignition timing based on the operating state of the engine and the knock generation state, and the output of the ignition timing determination means. In an ignition timing control device for an internal combustion engine, which comprises an ignition means for inputting and igniting an air-fuel mixture in an engine combustion chamber,
When the determined ignition timing reaches the advance upper limit value of the control characteristic when the first control characteristic is selected and the ignition timing is determined, the ignition timing is set further to the advance side than the upper limit value. A control characteristic initialization means for advancing the ignition timing to the set reference value and changing the control characteristic of the ignition timing to the second control characteristic when it is detected that knock does not occur until the reference value is reached. Configured as

(Operation) When the ignition timing reaches the upper limit value of the selected control characteristic,
Since the control characteristics are changed after further advancing and confirming that knock does not occur during that time, for example, if it is accurately determined that low octane fuel is used, knock will occur and control characteristics will be changed. Therefore, control hunting does not occur. Further, when it is erroneously determined that the low octane fuel is used, knock does not occur, so that the characteristics on the advance side can be appropriately changed.

(Example) Hereinafter, the Example of this invention is described. FIG. 1 shows the overall configuration of an ignition timing control system for an internal combustion engine according to the present invention. When described with reference to FIG. 1, reference numeral 10 denotes a multi-cylinder internal combustion engine for a vehicle, such as 6 cylinders. The internal combustion engine 10 is provided with an intake air passage 12, and the air introduced from the air cleaner 14 is introduced into the combustion chamber 20 of one cylinder via the intake manifold 18 while the flow rate thereof is adjusted by the throttle valve 16. A pipe 24 is connected to the intake air passage 12 at a proper position downstream of the throttle valve 16 and branched, and an intake air which measures the pressure of the intake air in the vicinity of the end portion of the branch passage by an absolute value to detect the engine load. A pressure sensor 26 is provided. In the vicinity of the cooling water passage 28 of the internal combustion engine 10, a water temperature sensor 30 as the engine water temperature detecting means is provided to detect the temperature of the engine cooling water, and at an appropriate position downstream of the throttle valve 16 of the intake air passage 12. Is provided with an intake air temperature sensor 32 to detect the temperature of the air taken in by the engine.

Further, a distributor 36 is provided in the vicinity of the internal combustion engine 10, and a magnet that rotates in synchronization with the rotation of a crankshaft (not shown) that rotates with the vertical movement of the piston 38 and a magnet facing it are provided inside the distributor 36. A Kunrank angle sensor 40 composed of a rotating body arranged in such a manner is housed and outputs a pulse signal at every predetermined crank angle. Furthermore, internal combustion engine
A piezoelectric knock sensor 44 for detecting vibration caused by knock generated from the combustion chamber 20 is provided at an appropriate position of the cylinder block 42 of the ten. Sensors such as the intake pressure sensor mentioned above
The outputs of 26, 30, 32, 40, 44 are sent to the control unit 50.

FIG. 2 shows the details of the control unit 50, which will be described with reference to FIG.
In addition, the output of the intake air temperature sensor 32 is input to the level conversion circuit 52 in the control unit and converted to a predetermined level, and then input to the microcomputer 54. The microcomputer includes an A / D conversion circuit 54a, an I / O 54b, a CPU 54
c, a ROM 54d, a RAM 54e, an operation counter and a timer (the counter and the timer are not shown). The output of the level conversion circuit is converted into a digital value in the A / D conversion circuit 54a in accordance with a command from the CPU 54c. After that, RAM54e
Is temporarily stored in. The output of the crank angle sensor 40 is input into the microcomputer via the I / O 54b after the waveform is shaped by the waveform shaping circuit 56.

Furthermore, the output of the knock sensor 44 is the control unit.
After being sent to 50, it is input to knock detection circuit 60. The knock detection circuit 60 includes a filter means 60a, a comparator means 60b, and a D / A conversion means 60c. In the comparator means 60b, a D / A conversion means from a microcomputer.
The knock state is detected by comparing the reference value sent through 60c with the sensor output value sent through the filter means 60a. When the knock sensor 44 of the resonance type that resonates at a frequency based on the knock to generate an output is used, the filter means 60a is unnecessary as shown by an imaginary line.

As is well known, the CPU 54c of the microcomputer 54 calculates the engine speed from the output of the crank angle sensor 40, determines the engine load condition from the output of the intake pressure sensor 26, and further determines the other operating conditions and the detected knock. The ignition timing is determined based on a control characteristic (hereinafter, referred to as a “zone”) set according to the octane fuel used from the occurrence state of the igniter, and an ignition device 70 including an igniter or the like is ignited via an output circuit 68, as described later. Directive and distributor
The ignition plug 72 of a predetermined cylinder is ignited through the
Ignite the mixture inside.

Next, the operation of the present control device will be described with reference to the flow chart of FIG. The characteristic of the present invention is not the ignition timing control itself but the switching of the control characteristics (hereinafter referred to as "zone reset") as described above. Therefore, the following description focuses on that point. Note that the program shown in FIG.
It is activated by interruption in the computer.

First, the engine cooling water temperature TW detected in S10 is compared with a predetermined value TWRS. This predetermined value is set to a value sufficient to judge whether or not the engine warm-up is completed, for example, 60 ° C. Assuming that the engine is in the constant temperature starting state, this determination is denied and the bit of the flag F-TWRS (described later) is set to 1 in S12, and then the process proceeds to S14, in which the zone type is determined.

Here, the zone will be described with reference to FIG.
In the present invention, 0,1,2
Are set. That is, zone 0 defines the ignition timing control characteristics when using fuel having an octane number of about 100, zone 1 uses fuel having an octane number of about 95, and zone 2 defines the ignition timing control characteristics. Is set to the retard side as shown in FIG. Incidentally, reference characters AVLMT0, 1, 2 in the same figure define the advance upper limit value of each zone. For example, if it is judged that the ignition timing is in zone 2, the ignition timing may basically advance beyond AVLMT2. Can not. These advance angle upper limit values are variably determined from the engine speed and the engine load. The advance angle upper limit value AVL
MT0 is equal to the basic ignition timing. Also, the retardation-side discriminant values RDLMT0, 1, 2 are set in each zone, which are used to determine the zone as described later. The discriminant value on the retard side is variably determined based on only the engine speed,
Only the discriminant value RDLMT2 on the most retarded angle side is a fixed value. The knock correction value for the ignition timing is controlled between the advance angle upper limit value AVLMTn and the retard angle determination value RDLMTn in any of these zones.

Returning to FIG. 3, assuming that the engine has been started in the zone determination starting from S14, the zone has not yet been determined, the result in S14 and S16 is negative, and the process proceeds to S18, in which the knock correction value θKNOCK (initial It is determined whether or not the value (zero) exceeds the retard determination value RDLMT0 of zone 1 in the retard direction (the retard direction value is shown as a positive value in the flow charts of FIG. 3 and subsequent figures).

Thus, when the engine is started, it is determined that the
Proceed to 20, where it is determined to be zone 0.

Calculation of the knock correction value will be described with reference to FIGS. 5 to 9.

FIG. 5 is an explanatory flow chart showing an example in which the correction value is retarded according to the occurrence of knock.

Explaining with reference to the figure, first, it is determined in S100 whether knock has occurred, and if it is determined that knock has occurred, it is determined in S102 whether or not the value of the continuous retarded ignition number NAFTNK (described later) remains. When the program is started for the first time, the initial value is zero, and the result is negated, and the process proceeds to S104. As shown, this value is the knock frequency counter value C
It is set to increase stepwise in proportion to KNOCK.

Next, in S106, it is judged whether or not the continuous retarding process ignition number NAFTNK is zero, and when it is denied, the number is decremented by 1 in S108, and in S110, the retarding unit amount DKNOCK is added to the correction value θKNOCK. To determine whether the retard target value corrected in S112 exceeds the maximum angle discriminant value of zone 2, and if it is determined that the retard target value exceeds the maximum angle discriminant value in zone 2, the maximum retard reference value is corrected in S114. Replace with. This is to prevent the exhaust temperature from rising excessively. As is apparent from FIG. 5, when the continuous retarding ignition number NAFTNK is set to 2 or more, the retarding process is continuously performed even if the occurrence of knock is denied at the start of the next program. (S10
0,106,108,110).

FIGS. 7 to 9 show a case where the correction value is corrected to the advance side. Referring to the flowchart of FIG. 7, first, in S200, the continuous knock non-occurrence ignition number counter value NKN
It is determined whether or not OCK has exceeded a predetermined advance standby ignition number AVCNTN. If it is determined in S200 that no knock occurs during the predetermined number of ignitions, the process proceeds to S202, where the advance angle unit amount DADV is determined. FIG. 8 is a flow chart showing the subroutine, and the advance unit quantity is retrieved from the table shown in FIG. 9 in S202A. As shown, the advance angle unit is set based on the engine speed and the engine load. As will be described later, the zone reset is considered when the correction value is advanced and coincides with the advance upper limit value, but the advance upper limit value is variable depending on the engine speed and the engine load as described above. Since it is set, the advance angle unit amount gives the same characteristics.

Next, in S204, the correction value is subtracted by the advance unit amount to correct in the advance direction, and in S206, the continuous knock non-occurrence ignition number counter is reset to zero. Next, the process proceeds to S208, and it is checked for each zone whether or not the correction value thus corrected for the advance does not exceed the upper limit of the advance. That is, for example, when it is determined in S208 that it is in zone 2, the flags F-ZROK21, F are determined in S210 and 212.
After confirming that the bit of −ZRS21 (described later) is 0,
4 and the correction value is compared with the lead angle upper limit value for that zone.
If it is determined that the value is exceeded in the advance direction, the upper limit value is set as a correction value in S216. If it is determined in S210 or 212 that any bit of the flag is set to 1,
Proceeding to S218, the correction value is compared with a reference value RDRL1 (described later),
If it is exceeded in the advance direction, it is limited to that value in S220. When it is determined that the vehicle is in zone 1, S224-23
If it is determined that the vehicle is in zone 0 in step 4, the same type of check is performed in steps S236 to 238.

The knock correction value thus determined is added to the basic ignition timing,
Furthermore, the final ignition timing is determined by adding other correction values such as the water temperature correction. However, since this point is known and has no relation to the gist of the present invention, further description will be omitted.

Returning to FIG. 3 again, as long as the correction value does not exceed the retarding direction of zone 0 in S18, the ignition timing is determined by determining that it is zone 0, but during the engine warm-up process, between the piston and the cylinder. Since the gap between the pistons is large, the piston hits the cylinder wall strongly during the combustion stroke, and in such a state the mechanical noise also increases due to the high viscosity of the lubricating oil.
It may be erroneously detected that knock has occurred from these noises even though knock has not occurred. As a result, the correction value is corrected to the retard side as described with reference to FIG. 5, which may exceed the retard determination value of zone 0 in S18 and may be determined to be zone 1 in S22. That is, even when fuel having an octane number of 100 corresponding to zone 0 is used, it may be determined to be zone 1 on the relatively retard side. Once it is determined to be in zone 1, the ignition timing is limited to the advance angle upper limit value of zone 1 as described above even if no knock has occurred, so that the engine output is unnecessarily lost.

In view of such inconvenience, in this example, it is made easy to reset the zone at the time when the warm-up is finished first. That is, if it is determined that the cooling water temperature exceeds 60 ° C in S10 after the warm-up ends, S
In step 26, it is judged whether the bit of the flag F-TWRS is reset to 0. Since this flag is set to 1 in S12, this determination is denied and the process moves to S28, in which the bit of the flag F-TWRS is reset to 0, and the bit of the flag F-TWZRS is set to 1. Next, in S30, the values of the timers TZRS21 and TZRS10 are set to the predetermined value TZ.
Replaced with RS21W and TZRS10W and flag F-ZRSF-ZRS2 in S32.
The bits of 1, F-ZROK10 and F-ZROK21 are reset to 0 (note that the bit of the flag F-ZROK10 is also reset to 0 in S24 even when it is determined to be zone 1 in S22). These flags and timer will be described later.

The zone reset determination is performed in cooperation with the procedure shown in the flowcharts of FIGS. FIG. 10 shows that the zone reset determination is permitted (the flags F-TWZRS, F-Z described above).
Responding to this, RS21, F-ZRS10 is indicated by bit-on), and Fig. 11 shows that zone reset permission (F-ZROK21,1 described above) is permitted.
(Indicated by 0 bit on).
It should be noted that the actual zone reset itself is performed under predetermined conditions upon receiving the zone reset permission in FIG.

Referring to FIG. 10, first, when the flag F-TWZRS indicating that the cooling water temperature exceeds 60 ° C. and the determination permission by the completion of the warm-up from the low temperature start has been established in S300 is confirmed, the process proceeds to S302. Then, the type of the zone is determined there. As described above, assuming that it is now erroneously determined to be zone 1, the determination in S302 is denied, the determination in S304 is affirmed, and the process proceeds to S306, where it is determined whether the correction value has returned to the advance angle upper limit value of zone 1. If it is determined that the angle has not been advanced, the timer TZR is determined in S308.
(To be described later) is reset (started), and the program is once ended. That is, the zone reset determination is not permitted until the ignition timing returns to the advance angle upper limit value of the zone.

If it is determined that the ignition timing has returned to the upper limit value at the time of starting the program several times, the process proceeds to S310 to determine whether or not the flag F-ZRS10 is bit-on. Since this flag was previously turned off in S32 of the flowchart of FIG. 3, the determination is denied and the process proceeds to S312, where the bit off of the reset permission flag is similarly confirmed, and the warm-up is performed in S314. It is confirmed that the bit of the reset determination permission flag by the end is on, and the process proceeds to S316, where the measured value of the timer TZR is compared with a predetermined value TZRS10,
The program is temporarily terminated until the time has elapsed.

That is, the timer measures the elapsed time since the reset determination permission was established. Here, the predetermined value TZRS10 is set to, for example, 5 seconds. Although this value was previously replaced by TZRS10W in S30 of the flow chart of FIG. 3, the replacement value TZRS10W is set to 2 seconds, which is shorter than that value. That is, as described above, if the zone reset is performed immediately when the advance angle upper limit value AVLMTn is reached, control hunting may occur. Therefore, in the present invention, the zone reset is performed only when various conditions are satisfied. Configured. Therefore, even if the zone reset condition is satisfied, the predetermined period of time has elapsed, and it is necessary to confirm that the operating state is in a steady state and confirm that knocking does not occur during that period, and perform a careful reset. However, in the reset judgment at the end of warm-up, the measurement time was shortened because it is intended to remedy the erroneous zone determination due to the erroneous detection of knock.

When it is confirmed that 2 seconds have elapsed in S316 when the program is started several times, the process proceeds to S318, where the flag F-ZRS10 is set.
Is turned on (zone reset determination is permitted), the timer value is reset in S308, and the program ends. Here, the suffix 10 in the flag indicates that determination of reset from zone 1 to 0 is permitted.

After receiving the zone reset judgment permission,
Zone reset permission is performed on the chart. That is, in the figure, first, in S400, it is determined whether or not the knock frequency counter value CKNOCK is less than the predetermined value KN. Here, the knock frequency is determined from the ratio of the number of knock generation ignitions to the predetermined number of ignitions, for example, whether or not the number of knocks generated at 120 ignitions is less than 2 ignitions. When it is determined in S400 that the knock occurrence frequency is less than the predetermined value, it is subsequently determined in S402 whether the reset determination permission is established from zone 2 to 1. Since it is the permission to judge from zone 1 to 0, the judgment in S402 is denied, the judgment in S404 is affirmed, and the judgment in S4 is made.
When it is confirmed in 06 that the correction value has advanced to the reference value RDRL0, the bit of the flag F-ZROK10 is set to 1 in S408 to permit zone reset, and in S410, the zone reset determination permission flag becomes unnecessary. Bit off.

This will be described with reference to FIG. Although the figure shows the reset from zone 1 to zone 0,
In this embodiment, the zone reset is performed when the following condition is satisfied. That is, the knock correction value θKNOCK is the advance angle upper limit value AVLM of the zone.
Advance to T1 (S306 in Fig. 10) (point1) After that, a predetermined time TZRS10 (or TZRS10W) has passed (S316, 324 in Fig. 10) (point2) Zone reset judgment permission (F-ZRS10 =
1) is performed, and the ignition timing is advanced by a unit amount DADV.

When the ignition timing is further advanced and reaches the reference value RDRL0, the zone reset is permitted (F-ZROK10 = 1). (FIG. 11, S408) (point3) Next, when the state in which the engine operating state changes and the reference value RDRL0 matches the advance angle upper limit value AVLMT0 of the upper zone 0 is detected, the zone is actually changed from 1 to 0. Reset (S36 to S44 in Fig. 3) (point4) As shown in Fig. 4, the reference value RDRL0 is set to the advance side of ΔRL0 from the advance upper limit value of zone 1, but it advances to zone 0. There is a difference from the corner upper limit. However, since these advance angle upper limit values are variably set based on the engine speed and the load, they coincide in the low load side operation region. Therefore, the reset is actually performed in the same operation state to prevent a sudden change in the ignition timing characteristics (this reference value is the same for the zone 2 and RDRL1 = AVLMT2-ΔRL1). As shown by the broken line in FIG. 12, when the knock occurs in the middle of the advance and it is determined that the frequency is equal to or higher than the predetermined position, the zone reset is stopped (FIG. 11, S4).
12).

At the end of warm-up, as shown in FIG.
In step S38, if it is confirmed that the advance value has reached the reference value and the zone is reset from 1 to 0 in step S40, the flag F-ZROK10 is bit-off in step S42, and the flag is set in step S44. Since the F-TWZRS is bit-off, the reset due to the warm-up end is performed only once when the warm-up from the low temperature start is completed, and is not performed again until the engine is stopped thereafter.

Next, zone reset at the time of high load will be described.

In FIG. 10, if the result in S300 is NO, then in S320, the engine speed NE is compared with a predetermined speed NEZR. This predetermined number of revolutions is a low number of revolutions such as about the idling number of revolutions.

If it is determined in S320 that the engine speed has exceeded the idle range, then in S322 the load condition of the engine is determined by comparing the intake pressure PBAD with a predetermined value PBKNZ. This predetermined value is set to a value sufficient for discriminating the high load state. FIG. 13 shows the characteristic thereof. As shown in the figure, the predetermined value PBKNZ is set variably with respect to the engine speed, and zone reset is judged in a region where knock easily occurs to confirm its suitability. When it is determined in S322 that the vehicle is in a high load state, the process proceeds to S302 and subsequent steps, and a zone reset determination during high load is performed.

Here again, taking the reset from zone 1 to 0 as an example, the determination in S302 is denied, the determination in S304 is affirmed, and the correction value θKNOCK reaches the advance upper limit value of zone 1 in S306. To wait. When the arrival is confirmed in S306, the process proceeds to S324 via S310, 312, 314, and confirms that the timer value has passed a predetermined time (5 seconds). When it is confirmed that the time has elapsed, the routine proceeds to S326, where the counter value CZRS10 for counting the number of reset determination permits is compared with a predetermined value ZRS10.
This reset determination permission number counts the number of times the reset determination permission is canceled after the knocking occurs more than a predetermined frequency after the reset determination permission is established, and the predetermined value is appropriately set to 5 times or the like. When this step is looped for the first time, the determination is naturally denied, and the process proceeds to S328, where the counter value is incremented, the bit of the reset determination permission flag is set to 1 in S318, and the program is temporarily terminated. still,
When it is determined in S322 that the program is not in the high load state at the next and subsequent program startups, the count value is decremented through S332 to 338, and the timer value is also reset in S340.

When it is determined that the count value has reached the predetermined number of times in S326 when the program is started several times, the process proceeds to S330, and the timer value TZRS10 (for example, 5 seconds) is set to TZR10L (for example, 25 seconds).
To rewrite. That is, it is changed so that the zone reset permission is hard to be established, which means that the operation state such as being interrupted by knocking each time with the intention of zone reset is using fuel with a low octane number,
This is because even if the zone is reset, it is expected that the zone will be returned to the original zone again, and that the ignition timing control characteristics will change frequently. Therefore, control hunting is avoided by configuring such that zone reset is unlikely to be established in such an operating state. After it is confirmed that the correction value reaches the reference value in the flow chart of FIG. 11 when the zone reset determination permission is made in S318 (S4
04-410), the zone is reset after waiting for the reference value to coincide with the advance angle upper limit value of zone 0 in the flow chart of FIG. 3 (S36-44). That is, as shown in FIG. 13, the zone reset is determined when the engine is in a high load range equal to or higher than a predetermined rotation speed, and the zone reset is executed at a low load where the predetermined value matches the advance angle upper limit value. With this configuration, it is possible to wait for a decrease in the engine speed even when the zone is erroneously determined during acceleration, as compared to the case where the zone reset is determined at the predetermined engine speed previously proposed by the present applicant. And zone reset is possible. Also, if it is correctly determined that the vehicle is in zone 1 (or 2) using low octane fuel, if the zone is uniformly reset when the engine speed drops, knock will occur in the upper zone and the zone must be changed again. However, as described above, the standby time is extended and the angle is advanced to make a determination in an area where knock is likely to occur, which makes it difficult to perform zone reset when using low octane fuel and prevents control hunting. can do.

Although the zone reset has been described for zones 1 to 0, the situation is the same when resetting from zone 2 to 1. That is, if it is determined in S34 that the correction value exceeds the retardation determination value RDLMT1 of zone 1 in FIG.
At 48, it is determined to be zone 2, and thereafter the ignition timing characteristic is controlled based on it. Thus, in this state, when the warm-up ends (S300 in FIG. 10) or the engine reaches a high load (S322 in FIG. 10), S342 to S360 to S342 to S360 (S362, 364) in the flowchart of FIG. ), The zone reset judgment permission from zone 2 to zone 1 is established,
In the flow chart of FIG. 11, the zone reset permission from zone 2 to 1 is established through S400, 402, 414 to 418, and the reference value RDRL1 of zone 2 and the progress of zone 1 are passed through S50 to S58 in FIG. Angle upper limit AVLMT
Waiting for a match with 1, reset to zone 1 is executed.

Since the present embodiment is configured as described above, even if erroneous detection of knocking during warm-up and erroneous zone determination can be performed, it can be reliably corrected at the end of warm-up.

In addition, since the zone reset is determined at the time of high engine load regardless of the engine speed, even if the zone is incorrectly determined during acceleration, correction can be made without waiting for the engine speed to decrease, and low When an octane fuel is used and a zone corresponding to the octane fuel is properly selected, there is no danger of occurrence of control hunting because the zone is not uniformly reset after waiting for a decrease in the engine speed.

Further, in the zone reset, the determination time is set to be relatively long and the advance is made to monitor the occurrence of the knock, so that the zone reset can be surely performed and the control hunting can be avoided.

In the above, the timer value (S316, 324, 350, 354) in the flow chart of FIG. 10 is indicated by time, but this may be the number of ignitions.

Also, in the flow chart of FIG. 10, when the predetermined number of times has been confirmed in S326, the timer value is changed from 5 seconds to 25 seconds in S330. In this case, the changed value should be kept constant at 25 seconds. Instead, it may be variable in proportion to the counted number, for example, 3 times = 20 seconds, 5 times = 25 seconds, and 7 times = 30 seconds.
Needless to say, this value may be the number of ignitions.

Although ΔRL0,1 has been described with reference to FIG. 4, this value may be a fixed value or a variable value. In particular, in the determination of the zone reset due to the end of the warm-up, in addition to shortening the timer value (flow chart S30 in FIG. 3) or separately from the above, in order to facilitate the zone reset, the value of ΔRL0,1 is changed. It may be made smaller and the arrival at the reference value RDRL0,1 may be accelerated.

(Effect of the invention) When the determined ignition timing reaches the advance upper limit value of the first control characteristic, the ignition timing control device for the internal combustion engine according to claim 1 further advances the advance angle beyond the upper limit value. Since the ignition timing is advanced to the reference value determined on the side and the second control characteristic is changed when it is detected that knock does not occur until the reference value is reached, for example, use of low octane fuel If it is accurately determined that knocking does not occur and the control characteristics are not changed, control hunting does not occur. Further, when it is erroneously determined that the low octane fuel is used, knock does not occur, so that the characteristics on the advance side can be appropriately changed.

The apparatus according to claim 2 is configured such that after the ignition timing reaches the advance upper limit value, the advance is advanced after confirming the elapse of a predetermined period, so the initialization is performed after confirming the stability of the operating state. be able to.

The apparatus according to claim 3 is adapted to change when the ignition timing reaches the reference value and then the reference value coincides with the advance upper limit value of the two-control characteristic. Therefore, the ignition timing changes abruptly at the time of change. Therefore, there is no sudden torque fluctuation.

The apparatus according to claim 4 is provided with counting means for counting the number of times the ignition timing reaches the advance upper limit value, and when the count value reaches the predetermined value, the predetermined period is extended, so that knock occurs. As a result, it is difficult to perform the initialization in the operating state where the initialization is often interrupted, and thus the control hunting can be prevented.

Since the apparatus according to the fifth aspect is provided with the same counting means and is configured to extend for a predetermined period according to the counted value, it is possible to achieve the same effect as the preceding paragraph.

In the apparatus according to the sixth aspect, since the occurrence of knock is detected from the knock frequency, it is possible to improve the initialization accuracy without being affected by the knock that occurs sporadically.

The apparatus according to claim 7 is configured such that the advance angle is performed in a predetermined operation state. Therefore, by performing the advance angle in a region where knock is likely to occur, for example, in a high load state, initialization is made difficult, resulting in a result. Therefore, control hunting can be prevented.

[Brief description of drawings]

FIG. 1 is a schematic diagram of an ignition timing control device for an internal combustion engine according to the present invention, FIG. 2 is a block diagram showing details of a control unit thereof, and FIG. 3 is a zone setting and zone reset operation of the control device. Flow chart, FIG. 4 is an explanatory view showing zones, FIG. 5 is a flow chart showing retard correction of knock correction value, and FIG. 6 is an explanation showing continuous retarding ignition number characteristic used therein. FIG. 7 is a flow chart showing the advance angle correction of the knock correction value, FIG. 8 is a flow chart showing the search of the advance angle unit amount as the subroutine, and FIG. 9 shows the characteristics of the advance angle unit amount. FIG. 10 is a flow chart showing zone reset determination permission, FIG. 11 is a flow chart showing zone reset permission, and FIG. 12 is an explanatory timing chart showing zone reset and FIG.
FIG. 13 is an explanatory diagram showing the zone reset operation area. 10 internal combustion engine, 12 intake air passage, 14 air cleaner, 16 throttle valve, 18 intake manifold, 20 combustion chamber, 24 pipe, 26 intake pressure sensor, 28 ... Cooling water passage, 30 ... Water temperature sensor, 32 ... Intake air temperature sensor, 36 ... Distributor, 38 ... Piston, 40 ... Crank angle sensor, 42 ... Cylinder block, 44 ... Knock sensor, 50 ... Control unit, 52 ……
Level conversion circuit, 54 ... microcomputer, 60 ...
... knock detection circuit, 68 ... output circuit, 70 ... ignition device

Claims (7)

(57) [Claims] Claims: 1. a. Engine operating state detecting means for detecting the operating state of the engine including at least engine speed and engine load; b. Knock detecting means for detecting knock occurring in the engine; c. Octane number of fuel used. Ignition timing control characteristic setting means for setting a plurality of types of ignition timing control characteristics corresponding to at least a first ignition timing control characteristic for low octane fuel and a second ignition timing control characteristic for high octane fuel, d. The output of the engine operating state detecting means, the knock detecting means, and the ignition timing control characteristic setting means is input, and the control characteristic corresponding to the octane number of the fuel used is selected based on the knocking generation state. Based on that, the engine operating state and knocking are selected. The ignition timing determining means for determining the ignition timing from the generation state of the engine, and e. The ignition means for inputting the output of the ignition timing determining means to ignite the air-fuel mixture in the engine combustion chamber, In the ignition timing control device for an internal combustion engine, f. When the first control characteristic is selected and the ignition timing is determined, when the determined ignition timing reaches the advance upper limit value of the control characteristic, When the ignition timing is advanced to a reference value set further to the advance side than the upper limit value, and when it is detected that knock does not occur until the reference value is reached, the ignition timing control characteristic is set to the second control. An ignition timing control device for an internal combustion engine, comprising: a control characteristic initialization means for changing to a characteristic. 2. The control characteristic initialization means further comprises a measuring means for measuring an elapsed period after the ignition timing reaches the advance upper limit value of the first control characteristic, and the measurement period reaches a predetermined period. The ignition timing control device for an internal combustion engine according to claim 1, wherein the ignition timing is advanced to the reference value after it is confirmed. 3. The advance upper limit value of the first and second control characteristics is variably set according to the engine operating state, and the control characteristic initialization means sets the ignition timing to reach the reference value. After that, when the reference value coincides with the advance upper limit value of the second control characteristic or is located on the advance side thereof, the control characteristic of the ignition timing is changed to the second control characteristic. The ignition timing control device for an internal combustion engine according to claim 1. 4. The control characteristic initialization means further comprises counting means for counting the number of times the ignition timing reaches the advance upper limit value of the first control characteristic, and when the count value reaches a predetermined number, The ignition timing control device for an internal combustion engine according to claim 2, wherein the predetermined period is extended. 5. The control characteristic initialization means further comprises counting means for counting the number of times the ignition timing has reached the advance angle upper limit value of the first control characteristic, and extends the predetermined period according to the count value. The ignition timing control device for an internal combustion engine according to claim 2, wherein the ignition timing control device is configured as described above. 6. The ignition timing control device for an internal combustion engine according to claim 1, wherein the control characteristic initialization means detects the occurrence of the knock based on a knock occurrence frequency within a predetermined period. 7. The internal combustion engine according to claim 1, wherein the control characteristic initialization means starts the advance when the engine operating state is in a predetermined region. Ignition timing control device.