JPH01200060A - Octane number detecting device for engine - Google Patents

Abstract

PURPOSE:To prevent the erroneous judgement of octane number by integration- calculating the retardation quantity of ignition timing within a prescribed time and calculating the average value and judging the octane number of the used fuel of the basis of the magnitude of the average value, in order to suppress knocking. CONSTITUTION:An ignition timing control means 61 for an engine arbitrarily retards the ignition timing according to the intensity of generation of knocking which is detected by a knocking detecting means, and advances the ignition timing by a prescribed value when knocking vanishes. In this case, a calculating means 63 which integration-calculates the retardation quantity of the ignition timing of the control means 61 within a prescribed judgement period for the octane number which is set by a timer 62, in the posterior stage of the ignition timing control means 61. Then, the output of the calculating means 63 and the standard retardation value which is based on the regular gasoline having a low octane number and set by a standard value setting means 64 are compared by an octane number judging means 65, and the octane number of the used fuel is judged.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an engine octane number detection device.

(Prior art) In general, knocking, a mechanical vibration caused by abnormal combustion (detonation) of the air-fuel mixture in the engine combustion chamber in a gasoline engine, occurs when the end gas (unburned on the end side in the direction of flame propagation) occurs before the original flame propagation after ignition. mixture)
This is caused by spontaneous ignition and temporary rapid combustion. Therefore, as a means for suppressing knocking, a knock sensor, which is generally a vibration pickup, detects the knock intensity indicated by the mechanical vibration level, and retards the ignition timing by an arbitrary amount according to the detected knock intensity to prevent the piston from rising. A method has been adopted to prevent knocking by reducing the combustion pressure near the point by a predetermined amount and suppressing the increase in the compression pressure of the end gas to a predetermined range (see, for example, Japanese Patent Laid-Open No. 58-28957).

By the way, the intensity and frequency of occurrence of the above-mentioned knocking vary greatly depending on the type of gasoline fuel (octane number) used in the engine. Compared to regular gasoline, the anti-knock properties are higher and knocking is less likely to occur.

Therefore, if the output value of the knock sensor used in the above-mentioned knock prevention means, that is, the detected knock intensity, is compared and determined with a predetermined reference intensity, the octane value of the fuel used in the engine can be determined according to the knock intensity that occurs. can be determined.

As described above, the retard m of the ignition timing as a knock prevention measure also corresponds to the knock intensity.

Therefore, as disclosed in, for example, Japanese Patent Laid-Open No. 58-143169, the octane number of the fuel used is detected based on the amount of retard of the ignition timing when knocking occurs, and according to the detected value, for example, high-octane Some measures have been taken to change and adjust the standard ignition timing when regular gasoline is used in a tan gasoline-only specification vehicle.

(Problem to be Solved by the Invention) However, like the conventional engine octane number detection device, the octane number of the fuel used is determined simply based on the amount of retard of the ignition timing corresponding to the knock intensity. So, there are problems in the following points.

First, the amount of retard of the ignition timing is set according to the knock intensity. Therefore, unless the knock intensity is detected accurately and with high precision, there is always a risk of misjudgment. In particular, as is clear from the above description, a knock sensor is generally attached to the outer wall of an engine, such as a cylinder block, and indirectly picks up mechanically transmitted vibrations by a vibration pickup. If the /N ratio is insufficient or if mechanical vibrations are likely to occur due to deterioration of the engine itself or the mount over time, the possibility of erroneous determination increases.

Furthermore, if the reference slice level is increased in an attempt to avoid such erroneous determinations, the determination period will become longer and responsiveness will deteriorate, impairing practicality.

(Means for Solving the Problems) The present invention has been made for the purpose of solving the above problems, and includes a knocking detection means for detecting the occurrence of engine knocking, and a method for detecting the knocking. ignition timing control means for arbitrarily retarding the ignition timing of the engine in accordance with the intensity of knocking when the knocking is detected by the means; and advancing the ignition timing by a predetermined value when the knocking disappears. ignition timing retard crushed average value calculation means for calculating the average value of the ignition timing retard amount within a predetermined period when knocking occurs; and the retard amount calculated by the ignition timing retard amount average value calculation means. and octane number determining means for determining the octane number of the fuel used in the engine by comparing the octane number with a predetermined reference set value.

(Function) According to the problem solving means of the present invention, first, the ignition timing is retarded by an arbitrary amount in accordance with the knock intensity detected by the knocking detection means to suppress knocking.

Then, when suppressing the knocking, the amount of retard of the ignition timing is accumulated within a predetermined period, and the average value is finally calculated, and the octane number of the fuel used is determined based on the magnitude of the average value. It is supposed to be done.

(Embodiment) FIGS. 1 to 4 show an octane number detection device for a supercharged engine according to an embodiment of the present invention.

First, FIG. 1 is a schematic diagram of the engine control system of the above-mentioned embodiment, and reference numeral l in the figure indicates an engine equipped with a turbocharger 6. In FIG.

The turbo supercharger 6 includes a compressor wheel 6a and a turbine wheel 6b, and these wheels are interconnected by a rotating shaft 7.

In the intake passage 2 that communicates with the intake manifolds 31 to 34 of each cylinder of the engine body 1, from the intake upstream side to the intake downstream side, an air cleaner 3, an air flow meter 4, and a compressor wheel of the turbo supercharger 6 are sequentially installed. 6a and a surge tank 5 are provided respectively.

The intake air taken in by the air cleaner 3 is measured by an air flow meter 4, compressed and pressurized by the compressor wheel 6a, and then supplied to the engine.

Also, the above engine! A turbine wheel 6b of the turbocharger 6 is provided in the middle of the exhaust passage 9,
The rotation of the turbine wheel 6b due to exhaust gas energy drives the compressor wheel 6a to supercharge the intake air. Further, the exhaust passage 9 is connected from the inlet side 8A to the outlet side 8A in the turbine housing portion of the turbine wheel 6b.
The inlet side 8A and outlet side 8B of the curved portion bypass the turbine housing and are provided with an exhaust gas relief passage 10, and the outlet 8B side end of the relief passage IO A waste gate valve 11 is installed in the section. The wastegate valve 11 is connected via a link lever 12 to an operating shaft of a wastegate actuator 13 made of a diaphragm, and the valve state is controlled by the wastegate actuator 13 during this time. The wastegate actuator 13 is connected to an intake pressure introduction passage 14 and an intake relief passage 1 to the intake passage 2 on the downstream and upstream sides of the compressor wheel 6a, respectively, via an electrically controlled three-way solenoid valve 15.
6, and the opening time of the three-way solenoid valve 15 is controlled by a boost pressure control signal Sp from the engine control unit 24, which will be described later. The opening period of the waste gate valve 2, that is, the relief amount of exhaust gas is adjusted to control the supercharging pressure of the intake air by the intake passage side compressor wheel 6a.

On the other hand, the reference numeral 22 is a distributor equipped with an engine speed and ignition timing pickup, and applies a high-voltage secondary current from an igniter (not shown) to the spark plugs 20, 20, etc. of the engine side number cylinders at a predetermined ignition timing. The actual engine speed NE and ignition timing G detected by the engine speed pickup and ignition timing pickup of the distributor 22 are as follows:
Each is input to the engine control unit 24.

Reference numeral 21 denotes a knock sensor (knock detection means) provided in the cylinder head of the engine main body l, which outputs a voltage output Vo according to the intensity of knocking in the engine, and outputs a voltage output Vo corresponding to the engine knocking intensity. , simply referred to as ECU) 24.

The ECU 24 is configured to include, for example, a microcomputer (CPU) as a calculation unit, a knock determination circuit, an octane number determination circuit, a memory (ROM and rLAM), an interface (I10) circuit, and the like. In addition to the above-mentioned detection signals, the interface circuit of the ECU 24 receives, for example, an engine starting signal (ECU trigger) from a starter switch (not shown),
An engine rotation speed detection signal NE from an engine rotation speed pickup, a detection signal Tw of engine cooling water temperature detected by a water temperature thermistor, and a throttle opening detection signal TVO detected by a throttle opening sensor.

Various detection signals necessary for various controls such as the crank angle signal θ, the air-fuel ratio such as the intake air amount detection signal Q detected by the air flow meter 4, ignition timing, knocking suppression, and octane number detection are also input.

The ECU 24 is functionally equipped with, for example, a knock determination circuit section 50 as shown in FIG. 2 and an octane number determination circuit section 60 as shown in FIG. When the determination is made, the knocking suppression control described below is carried out, and the octane number determination circuit 60 determines the octane number of the fuel used at that time.

First, the knock determination circuit section 50 is shown in FIG. The output voltage of the knock sensor 21 (
(See Fig. 5) Vo is input, and its peak value within a certain period after ignition (knock judgment period; see Fig. 6 (a)) is detected by the next peak value detection section 52, while the comparison reference level is calculated. The unit 53 calculates the average value (knock determination reference value; see FIG. 6(b)) of the knock sensor output Vo when no knocking occurs within the knock determination period. and,
Next, both values are compared by a knock determination section 54, and if the peak value exceeds the average value, a knock signal is generated.

This knock signal is manually inputted to a microcomputer 35, which is a calculating section, to calculate the number of times the above-mentioned peak value exceeds the average value, and the knock intensity is determined according to the calculated value. This knock determination value is shown as a step-shaped signal waveform as shown in FIG. 6(c).

When the knock strength is determined as described above, the sixth
Converting the judgment value in figure (c) to the waveform Vf in figure 7 (a),
The ignition timing rgf is calculated and determined according to the judgment value level as shown in FIG. 7(b), and the ignition timing of the next cylinder is retarded or advanced by feedback control to control the optimum ignition timing. When the signal in FIG. 7 is sampled, converted into an actual logic signal, and expressed in an easy-to-understand manner, it becomes as shown in FIG. 8.

The microcomputer 35 also includes an octane number determination circuit 60 equivalently shown in FIG.

The octane number determination circuit section 60 first operates as shown in FIG. 7(b) above.
The ignition timing control means 61 forms an ignition timing control signal such as The ignition timing retard m average value calculating means 63 calculates the average value of 0-unit ET・AV, and the output θRET''AV of the ignition timing retard amount average value calculating means 63 is calculated by the reference value setting means 64. Compared to the standard retard value θ mouth EG based on regular gasoline with a low octane rating,
It is comprised of an octane number determining means 65 which determines whether it is regular gasoline if [θROεT-Av>θREGJ, or high octane gasoline if [θRET・AV<θREGJ].

Next, the operation of this octane number determination circuit section 60 will be explained in more detail with reference to the flowchart of FIG.

First, in step S1, the standard ignition advance angle OBASE (-〇■■o) is read out from the basic advance angle map (high-octane map) corresponding to the standard ignition timing setting means of the engine (high-octane exclusive specification) and set. Next, the operating state of the timer T that determines the regular determination time T EG for determining the use of regular gasoline, which is the original target of determination, is initially set.

Then, in step S3, the actual intake air IQ and engine speed NE of the engine in the current operating state are respectively read. Thereafter, the process further proceeds to step S4, where it is determined using these parameters as whether the current operating state belongs to a knock region where knocking is likely to occur, such as a low speed, high load operating region.

If the result is YES, the process advances to step S5 to actually determine the presence or absence of a knock signal, while if the result is no, the process directly returns to step S2 described above and repeats the operations up to this point.

There is a knock signal at the above step SθRET (Y E S
), when it is determined that knocking has actually occurred, the process proceeds to step S6, where the set determination time TREG of the regular determination timer T is decremented (TREG-1) for each cycle, and further Step S
In step 7, in synchronization with the start of decrement of the timer T, the ignition timing retard amount 0RET for each cycle is calculated.

Next, the process proceeds to step S8, and the calculated values 0RET, 0RET, . . . sequentially calculated in step S7 are integrated (Σ
θRET-θRε 1+θR1:Tt+θRET3・Fist・・θnETn) and go. This integration is performed until the timer T is decremented (T REG=0).

Next, the process proceeds to step S9, where it is determined whether the setting determination time TREG of the timer T has elapsed (TREG=0), and if YES (TREG=0), the process further proceeds to step S9.

. Based on the integrated value of step S8, calculate the average value of the ignition timing retard amount (ORET・^V−ΣθRE T / n
) is calculated.

Finally, proceed to step SI+, and convert the calculated value 0RET・AV to the standard retard 1ORFG (ORET・LT) set based on regular gasoline.
EG) (On+4・^■〉θF pressure G?), and if the above calculated value θRET・AV is YES, it is determined that it is regular gasoline, while the opposite is ＼
If it is 0, it is determined that it is high octane gasoline.

If it is determined in step Sll that the gasoline is regular gasoline, the process advances to step Slt and the reference ignition timing OBASE-θ set in step S1 is set.
11■0 is reset to θ13AsE=θREG to control the ignition timing thereafter. On the other hand, in the case of high octane, the process directly returns to step S2.

According to the configuration of the above-described embodiment, when high-octane gasoline is used, even if the detection signal Vf of the noise sensor 21 described above contains a noise component due to mechanical vibration other than engine knock, The detection signal Vf itself is shown as the average value of the peak level within a predetermined knock judgment period, and the ignition timing retard m itself that is controlled correspondingly is also shown as the average value within the regular judgment time TREG. . Then, this average value is calculated based on the DC component within the above-mentioned judgment time T REG of the amount of retard at the time of ignition corresponding to each vibration component as shown by diagonal lines in FIGS. 9(a) and (b), for example. It is calculated by dividing the integrated value (knock component retard amount > noise component retard amount) by the number of integrations.
The accuracy of the calculated average value 0RET·AV is high and almost does not include the retard claw due to the above-mentioned noise component.

(Effects of the Invention) As described above, the present invention includes a knocking detection means for detecting the occurrence of knocking in an engine, and when the knocking detection means detects the occurrence of knocking, the engine In an engine, the engine is equipped with ignition timing control means that arbitrarily retards the ignition timing and advances the ignition timing by a predetermined value when the knocking disappears. Average retard amount for the period
The octane number of the fuel used in the engine is determined by comparing the ignition timing retard amount average value calculation means for calculating the average value and the retard amount calculated by the ignition timing retard amount average value calculation means with a predetermined reference setting value. The invention is characterized in that it is provided with an octane number determination means for determining the octane number.

That is, in the configuration of the present invention, first, the ignition timing is retard-controlled by an arbitrary amount in accordance with the knock intensity detected by the knocking detection means to suppress knocking.

When suppressing knocking, the ignition timing retard amount is accumulated within a predetermined period, and the average value is finally calculated, and the octane number of the fuel used is determined based on the magnitude of the average value. It is designed to be judged.

Therefore, it is possible to reliably avoid erroneous judgments caused by mechanical vibrations or the like that are not caused by knocking, and since there is no need to set a high slice level, it is possible to respond with good responsiveness within a short period of time.

[Brief explanation of the drawing]

FIG. 1 is a system diagram of an engine octane number detection device according to an embodiment of the present invention, FIG. 2 is a block diagram of a knock determination circuit of the same embodiment, and FIG. 3 is a block diagram of the octane number determination circuit of the same embodiment. FIG. 4 is a flowchart showing the octane number determination operation of the octane number determination circuit shown in FIG. An example waveform diagram,
6 to 8 are time charts showing the operation of the knock determination circuit shown in FIG. 2 in the above-mentioned embodiment apparatus, and FIG.
The figure is a time chart showing the operation of the octane number determination circuit of FIG. 3. ■... Engine body 2... Intake passage 6... Turbo supercharger 21... Knock sensor 22... Distributor 24... Engine control unit 30...・
-Filter circuit 35...Microcomputer 50...Knock judgment circuit section 60...Octane number judgment circuit section 61...Ignition timing control means 62...Timer 63...Ignition timing Retard amount calculation means 64...
Reference value setting means 65... Octane number determination means

Claims (1)

[Claims] 1. Knocking detection means for detecting the occurrence of knocking in the engine, and when the knocking detection means detects the occurrence of knocking, the ignition timing of the engine is arbitrarily retarded according to the intensity of the knocking, while the above-mentioned knocking disappears. ignition timing retard amount average value calculation for calculating the average value of the ignition timing retard amount within a predetermined period when knocking occurs, in an engine equipped with ignition timing control means for advancing the ignition timing by a predetermined value if the knocking occurs. and octane number determination means for determining the octane number of the fuel used in the engine by comparing the retard amount calculated by the ignition timing retard amount average value calculation means with a predetermined reference setting value. Engine octane number detection device.