JPH02211381A - Ignition timing controller for internal combustion engine - Google Patents

Abstract

PURPOSE:To obtain the optimum driving characteristic without incurring the reduction of the engine output due to the unnecessary delayed angle by constituting a correction control range selecting means so that the switching of the correction control range is not carried out when the detected engine temperature is below a prescribed value. CONSTITUTION:An ignition timing controller is constituted of a correction control range selecting device 4 which receives the output of an octane number judging means 3 and selects the correction control range corresponding to the knock of the ignition timing according to the cotane number, ignition timing control means 5 which receives the outputs of an operation state detecting means 1 and a knock detecting means 2 and determines the ignition timing according to the operation state and an igniting means 6 which receives the output of the means 5 and ignites the mixed gas in an engine combustion chamber. An engine water temperature detecting means 7 for detecting the cooling water temperature of the engine is installed, and when the engine water temperature detected by the engine water temperature detecting means 7 is below a prescribed value, switching of the correction control range by the correction control range selecting means 4 is suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an ignition timing control device for an internal combustion engine, and more specifically, to a device for controlling the ignition timing in response to a knock in the ignition timing. The present invention relates to an ignition timing control device for an internal combustion engine that does not switch the correction control range when the water temperature is low.

(Prior art) When knocking occurs in an internal combustion engine, it makes an abnormal noise that causes discomfort to the passengers, and if left untreated, it can cause serious damage to the engine, so it is necessary to monitor the occurrence of knocking. It is a common practice to retard the ignition timing when knocking occurs, and after the knocking has stopped, to return the retarded ignition timing to the advanced side by waiting for an appropriate number of ignitions or an appropriate amount of time. As an example, the technique described in Japanese Patent Publication No. 57-12027 can be mentioned.

In addition, recently, engines that use high octane fuel are being provided in response to the demand for higher output, but there are two types of engines that use high octane fuel and normal octane fuel. Since the ignition timing to be set is different, there is also a technology that determines the octane number of the fuel used based on the state of knock occurrence and switches the ignition timing control range to control the ignition timing so that it corresponds to the octane number of the fuel actually used. For example, Japanese Patent Application Laid-Open No. 1983
The technique described in Japanese Patent No.-104776 can be mentioned. In this technology, when it is determined that the fuel has a low octane value, the ignition timing is fixed to a relatively retarded side to prevent frequent knocking.

(Problem to be Solved by the Invention) By the way, in an internal combustion engine, the combustion condition is not good when the cooling water temperature is low. This ensures operability during the warm-up process. Therefore, the difference (knock margin) between the set ignition timing and the knock occurrence ignition timing (knock zone) decreases, and the frequency of knock occurrence tends to increase when compared with the warm-up completed state. As a result, when determining the octane number of the fuel used based on the frequency of knock occurrences, even when fuel with a high octane number is used, the frequency of knock occurrences is determined to be higher than the predetermined value, and it is mistakenly assumed that normal octane fuel is being used. As a result, the ignition timing is fixed to a relatively retarded control range, and there is a risk that the engine's output may not be fully utilized even after warm-up is complete and normal operation is resumed. Ta.

Therefore, the present invention eliminates the above-mentioned drawbacks of the prior art, and prevents switching of the correction control range when the engine water temperature is in a low operating state, thereby avoiding unnecessary reduction in engine output due to erroneous determination of the octane number. An object of the present invention is to provide an ignition timing control device for an internal combustion engine.

(Means for Solving the Problems) In order to achieve the above object, the present invention, as shown in FIG. knock detection means 2 for detecting the occurrence of knock by detecting the vibration of the knock detection means; octane number determination means 3 for determining the octane number of the fuel by inputting the output of the knock detection means; inputting the output of the octane number determination means for determination; a correction control range switching means 4 for switching a correction control range in response to knock in the ignition timing according to the octane number, inputting the outputs of the correction control range switching means, the operating state detecting means, and the knock detecting means; The ignition timing control means 5 determines the ignition timing accordingly, and corrects the determined ignition timing within the selected correction control range when knocking is detected, and inputs the output of the ignition timing control means to control the engine combustion chamber. In the ignition timing control device for an internal combustion engine, the ignition timing control device includes an ignition means 6 for igniting an air-fuel mixture, and includes an engine water temperature detection means 7 for detecting the engine cooling water temperature, and the correction control range switching means adjusts the output of the engine water temperature detection means. When the detected engine water temperature is below a predetermined value, the correction control range is not switched.

(Function) The ignition timing correction control range is configured not to change when the water temperature is low, so even though high octane fuel is being used at low water temperatures, it may be mistaken for normal octane fuel and the ignition timing control range will be retarded. It is not fixed to the side, so the engine output is not unnecessarily uniform.

(Example) The present invention will be described in detail below. FIG. 2 shows the overall configuration of an ignition timing control device for an internal combustion engine according to the present invention.
Referring to the figure, reference numeral 10 indicates a multi-cylinder internal combustion engine for a vehicle, which includes four cylinders or the like. The internal combustion engine 10 includes an intake air passage 12, and air flowing from an air cleaner 14 is introduced into the combustion chamber 20 of the - cylinder through an intake manifold 18 while its flow rate is adjusted by a throttle valve 16. A pipe 24 is connected to the intake air passage 12 at an appropriate position downstream of the throttle valve 16 to branch off, and near the end of the branch passage there is an intake air passage that measures the pressure of the intake air in absolute value to detect the engine load. Pressure sensor 26
is provided. Further, a water temperature sensor 30 serving as the engine water temperature detection means is provided near the cooling water passage 28 of the internal combustion engine 10 to detect the temperature of the engine cooling water, and is located at an appropriate position downstream of the throttle valve 16 in the intake air passage 12. An intake temperature sensor 32 is provided to detect the temperature of air taken into the engine.

Further, a distributor 36 is located near the internal combustion engine 10.
and a crank angle sensor consisting of a magnet that rotates in synchronization with the rotation of a crankshaft (not shown) that rotates as the piston 38 moves up and down, and a rotating body that is placed opposite the magnet. 40 is housed therein, and outputs a pulse signal at every predetermined crank angle. Further, a piezoelectric knock sensor 44 is provided at an appropriate position on the cylinder block 42 of the internal combustion engine 10 to detect vibrations caused by knocks generated from the combustion chamber 20. The outputs of the sensors 26, 30, 32°40.44 such as the intake pressure sensor mentioned above are:
It is sent to the control unit 5o.

FIG. 3 shows details of the control unit 50. To explain according to the figure, the outputs of the intake pressure sensor 26, water temperature sensor 30, and intake air temperature sensor 32 are inputted to a level conversion circuit 52 in the control unit to a predetermined level. After being converted into , it is input to the microcomputer 54 . The microcomputer includes an A/D conversion circuit 54a
, l1054 b, CPU54 cSROM54 d,
It is equipped with a RAM 54e, a calculation counter, and a timer (the counter and timer are not shown), and the output of the level conversion circuit is output from the A/D according to the command from the CPU 54c.
After being converted into a digital value in the conversion circuit 54a, R
Temporarily stored in AM54e. Further, the output of the crank angle sensor 40 is waveform-shaped in the waveform shaping circuit 56 and then input into the microcomputer via the l1054b.Furthermore, the output of the knock sensor 44 is sent to the control unit 50 and then , are input to the knock detection circuit 60. The knock detection circuit 60 includes filter means 60
a, comparator means 60b, and D/A conversion means 6
0c, and the filter means 60a has a comparator means 6
It is connected to the non-inverting input terminal of 0b, and its inverting input terminal is connected to the D/A conversion means 60c. Further, the comparator means 60b is connected to the microcomputer 54, and the microcomputer 54 is connected to the D/
It is connected to the A conversion means 60c. It should be noted that if a resonance type sensor that generates an output by resonating at a frequency based on knock is used as the above-mentioned knock sensor 44, the filter means 60a becomes unnecessary as shown by the imaginary line.

In this knock detection circuit 60, the sensor output is sent to the microcomputer 5 in the comparator means 60b.
The noise level is calculated and knock is determined by comparing it with the reference value set by the microcomputer 54, and to explain this point with reference to the timing chart of FIG. In the angular range (for example, ATDC 120 to 140 degrees), the noise level, which is the background value of engine vibration, is output as a comparison reference value to the D/A conversion means 60c. This angular range is referred to as a "noise gate" in FIG. show. The output value is D
It is converted into a -yt-log value by the /A conversion means 60c, and compared by the sensor output level comparator means 60b. The microcomputer 54 changes this noise level based on the comparison result. The noise level is set to be approximately near the peak value of the sensor output level.

Further, the microcomputer 54 calculates a predetermined coefficient (appropriately set according to the operating condition) based on the noise level in an appropriate rank angle range (ATDCIO to 50 degrees) including the fuel condition shown as "knock gate" in FIG. The knock determination level is calculated by multiplying the knock determination level by the value of the knock determination value), and the calculated knock determination level is output to the comparator means 60b via the D/A conversion means 60c. The comparator means 60b compares the sensor output level with the knock determination level, and determines that a knock has occurred when the sensor output exceeds the knock determination level. Note that the calculation of the noise level and knock judgment level in such a knock detection method is performed using a software method in the microcomputer 54, but it may also be detected in an analog manner using a hardware circuit. Various methods may be used to generate the sensor output, such as using the average value of the sensor output.

In addition, in the microcomputer 54, the CPU 54c
As is well known, the engine speed is calculated from the output of the crank angle sensor 40, the engine load condition is determined from the output of the intake pressure sensor 26, and the basic ignition timing is determined by searching the basic ignition timing map stored in the ROM 54d. Calculate the water temperature,
The basic ignition timing is corrected from other operating parameters such as intake temperature, and when there is a knock condition, the correction control range (described later) is adjusted.
The ignition timing is further corrected in the zone) to calculate the final ignition timing, and an ignition device 70 consisting of an igniter or the like is commanded to ignite via the output circuit 68.1. distributor 3
6, the spark plug 72 of a predetermined cylinder is ignited to ignite the air-fuel mixture in the combustion chamber 20.

Next, the operation of this control device will be explained with reference to the flow chart in FIG. Incidentally, the program shown in FIG. 5 is started by interruption in the microcomputer at every predetermined crank angle.

First, after reading the engine speed Ne and the cooling water temperature Tw in SIO, the process proceeds to S12, where the detected engine speed is compared with a predetermined idle speed NeIDL to determine whether the engine is in the idle speed range. This predetermined idle speed is appropriately set to a value such as 750 rpm, which is sufficient to determine whether or not the engine speed is in the idle range.

If it is determined in S12 that the rotation speed is not in the idle rotation range, the process proceeds to S14, where the timer counter Cl0L (down counter) that measures the time in the idle rotation area is reset, and the process proceeds to S16, where the zone which is the correction control range described above is reset. It is determined whether the flag FZONEI is set to 1 or not. Here, to briefly explain the zones with reference to FIG. 6, as mentioned above, the device according to the present invention is based on an on-vehicle internal combustion engine in which the ignition timing is set based on the use of high-octane fuel. . Since high octane fuel is not always used even in such in-vehicle internal combustion engines, the octane number of the fuel actually used is estimated based on the state of knock occurrence, and the ignition timing can be adjusted accordingly. The correction control range (zone) is different depending on the knock. That is, the number of knocks (knock frequency θKN) that occurs during a predetermined number of ignitions is calculated,
If it is within the predetermined value, it is determined that high octane fuel is being used and the zone is set to "ZONEO", and if it exceeds the predetermined value, it is determined that normal octane fuel is being used and the zone is set to "ZONEO". 1°. Figure 6 shows these two types of zones. As shown, "' ZO
The retard angle upper limit value θRDLMT at the time of knock occurrence is the same for NE O'' and "ZONB 1", but the advance angle upper limit value θADVLMT on the return side after the knock ends is set differently; In "ZONE O", it is possible to return to zero (same as basic ignition timing θig-BASH), but in "ZONE O", it is fixed to the predetermined value θprx before that.In other words, when the planned high octane fuel If it is determined that a fuel other than 1 is being used, the basic ignition timing is set to the advanced side assuming the use of high octane fuel, so determining the ignition timing based on that basic value will cause knock. Since this may occur frequently, the ignition timing is controlled by retarding the ignition timing by a predetermined value from the basic value to prevent frequent knocking, rather than returning the ignition timing to the basic value even after the knocking that has occurred has stopped. As mentioned above, as a result, the engine output is limited.

In addition, even in such a control method, zone determination is canceled when a change in the operating state is expected, and in this embodiment, as will be described later, zone determination is performed when the engine continues to be in an idling state for a predetermined period of time. are being discarded.

Returning again to the flow chart in FIG. 5, the flag F ZONEI is reset to O in the judgment of S16, that is, the current zone is not "ZONE 1" (for low octane) but "ZONE O" (for high octane). When it is determined that the cooling water temperature Tw is determined to be
Compare with NE. It goes without saying that this predetermined water temperature TwZONE is selected to be an appropriate value such as 65° C., since the present invention aims to eliminate the inconvenience caused by the cold advance setting.

When it is determined in 31B that the cooling water temperature is equal to or higher than the predetermined value and that the cooling water has been warmed up, the process proceeds to 320, where the value of the counter CKN that counts the knock frequency (JN, specifically, the knock frequency) is determined to be the predetermined frequency. CKNZONE or more, for example, it is determined whether knock occurs at 40th ignition out of 200 ignitions.If it is negative, the process proceeds to S22, where the zone determination flag is reset to zero and the same ZONE O' is determined), and at S24. The advance angle upper limit value θADVLMT is set to zero (degrees), and when the answer is affirmative, the knock frequency counter is reset in S26, and then the process proceeds to 528, where the zone determination flag is set to 1 (determined as "ZONE 1"), S
At step 30, the advance angle possibility is fixed at a predetermined value θFIX.

When it is determined in 31B that the current water temperature is lower than the predetermined value, the process jumps to S22 without determining the knock frequency in S20. Therefore, 32
There is no possibility that the ignition timing will advance to ZONE 1 and be determined to be in ZONE 1 and the degree of advancement will be limited. Therefore, the ignition timing will not be unnecessarily fixed to the retard side.

Furthermore, when it is determined in 316 that the engine is in "ZONE 1", the process jumps to 328 and subsequent steps, and when it is determined in S12 that the engine is in the idle rotation range, the process advances to S32 and decrements the idle rotation continuation time measurement counter Cl0L. , 334, when it is confirmed that the knock frequency counter CKN has reached zero, the knock frequency counter CKN is reset in 336, and the process proceeds to S22 and thereafter to adjust the correction control range.
NE O”.

That is, even when it is determined that ZONE 1 (for low octane) is selected, the determination is temporarily discarded after a predetermined period of idle state has elapsed to obtain control flexibility.

As described above, the ignition timing control device according to the present embodiment does not perform zone determination when the water temperature is less than a predetermined value, and the advance angle upper limit value of the zone is not limited.
Since the ignition timing is controlled as if it were in the engine, the engine output is not unnecessarily suppressed after warm-up.

(Effect of the invention) In the ignition timing control device for an internal combustion engine according to the present invention,
An engine water temperature detection means is provided to detect the engine cooling water temperature,
The correction control range switching means inputs the output of the engine water temperature detection means and does not switch the correction control range when the detected engine water temperature is below a predetermined value. Even when the engine shifts to the operating state, the engine is not forced into unnecessary retardation, resulting in an unnecessary drop in engine output, and it is possible to obtain optimal operating characteristics while avoiding knocking.

[Brief explanation of the drawing]

Fig. 1 is a diagram corresponding to claims of the present invention, Fig. 2 is a schematic diagram of a control device according to the present invention, Fig. 3 is a block diagram showing details of the control unit, and Fig. 4 is a knock detection circuit in the control unit. FIG. 5 is a flow chart showing the operation of this apparatus, and FIG. 6 is an explanatory diagram showing zones (correction control ranges) used in the flow chart. 1... Operating state detection means (intake pressure sensor 26, crank angle sensor 40), 2... Knock detection means (knock sensor 44, knock detection circuit 60, microcomputer 54L) 3... Octane number determination means (micro・
computer 54), 4...correction control range switching means (
Microcomputer 54), 5... Ignition timing control means (microcomputer 54), 6... Ignition means (ignition device 70, distributor 36, spark plug 72), 7... Engine water temperature detection means (water temperature sensor 30
), 50... Control unit, 54... Micro computer, 60... Knock detection circuit Applicant: Honda Motor Co., Ltd. Agent Patent attorney: Yoshi 1) Yutaka

Claims (1)

[Scope of Claims] a. Operating state detection means for detecting the operating state of the engine including at least the engine speed and engine load; b. Knock detection means for detecting the occurrence of knock by detecting engine vibration; c. d) an octane number determining means inputting the output of the knock detecting means to determine the octane number of the fuel; a correction control range switching means for switching, e, inputting the outputs of the correction control range switching means, the operating state detecting means, and the knock detecting means to determine the ignition timing according to the operating state, and when knock is detected; An internal combustion engine comprising: ignition timing control means for correcting the ignition timing determined in a selected correction control range; The ignition timing control device includes g, engine water temperature detection means for detecting the engine cooling water temperature, and the correction control range switching means inputs the output of the engine water temperature detection means so that the detected engine water temperature is a predetermined value. An ignition timing control device for an internal combustion engine, characterized in that the correction control range is not switched in the following cases.