JPS60202360A - Decision of octane value - Google Patents

Abstract

PURPOSE:To enable automatic decision on octane value of fuel by identifying it based on the frequency of knockings after the lag angle reaches the upper limit value in the ignition timing of a gasoline engine. CONSTITUTION:It is determined whether the lag angle reaches the upper limit value in the ignition timing set to match the octane value of a specified fuel according to outputs of a cylinder identifying sensor 19 and an angle of rotation sensor 18 and the like. When the frequency of knockings detected with a knocking sensor 10 or the like after the arrival at the upper limit exceeds the specified value, a CPU30 judges that the octane value of the fuel is lower than the octane value of the specified fuel thereby enabling an automatic decision on the octane value.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to an octane number determination method for automatically determining the octane number of various fuels used in gasoline engines.

[Prior Art] Conventionally, fuels of various octane numbers have been provided as fuel for gasoline engines, particularly gasoline engines for vehicles.

However, gasoline engines and the various control devices surrounding them are designed in advance to obtain the best operating conditions when using fuel with a predetermined octane number. When used in a gasoline engine, effects such as knocking and deterioration of fuel efficiency may occur.

Therefore, as seen in Japanese Patent Laid-Open No. 58-57072, various efforts have been made, such as a technique in which an ignition timing control map corresponding to the difference in octane number is prepared in advance and the map is selected according to the fuel being used. being paid.

However, these methods also determine the octane number by simply operating a switch by the driver, which not only gives the driver a sense of complication (but also causes knocking if the driver forgets to operate the switch). occurs frequently, and the purpose cannot be achieved.

[Object of the Invention] The present invention was completed after intensive study by the inventor, and its purpose is to provide an octane number determination method that automatically determines the octane number of fuel used in a gasoline engine. There is.

[Structure of the Invention] The structure of the present invention to achieve the above object, as shown in the sample structural diagram of FIG. 1, performs ignition timing control with a predetermined retardation amount as an upper limit in accordance with fuel of a predetermined octane number. In the method for determining the octane number of a gasoline engine, knocking occurs at a predetermined frequency or more (P2) even after the ignition timing retard amount reaches the upper limit value (Pl), so that the 1992 valence of the fuel reaches the predetermined 1992 value. Judgment that the value is lower than the value (P3) t7. y′,
The gist is the A-phthane number determination method.

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

First, FIG. 2 is an explanatory diagram showing a gasoline engine and its peripheral equipment to which the method of the present invention is applied.

1 is a gasoline engine body dedicated to high octane fuel, 2 is a piston, 3 is a spark plug, 4 is an exhaust manifold, 5 is an oxygen sensor that is connected to the exhaust manifold 4 and detects the residual oxygen concentration in exhaust gas, 6 is an oxygen sensor Fuel in the intake air of Ganlin engine body 1! 7 is an intake manifold, 8 is an intake air temperature sensor that detects the temperature of the intake air sent to the gasoline engine main body 1, 9 is a water temperature sensor that detects the water temperature of the gasoline engine water, 10 is a Like the water temperature sensor 9, a knocking sensor is attached to the cylinder of the gasoline engine 1 and detects the occurrence of knocking in the gasoline engine 1; 11 is a throttle valve; 14 is an air flow meter that measures intake air Bl; 15 is a pulsation of intake air. Each represents a surge tank that absorbs .

16 is an igniter that outputs the high voltage necessary for ignition; 17 is a distributor that is linked to a crankshaft (not shown) and distributes the high voltage generated by the igniter 16 to the spark plugs 3 of each cylinder; 18 is a distributor A rotating stand sensor 19 is attached to the distributor 17 and outputs 24 pulse signals per one revolution of the distributor 17, that is, two revolutions of the crankshaft.
Cylinder discrimination lens that outputs one pulse signal per rotation of 7 - 'J120 is an electronic control circuit, 21 is a key switch, 2
2 represents a starter motor. -26 does not represent a vehicle speed sensor that is linked to the axle and optically transmits a pulse signal according to the vehicle speed.

Next, FIG. 3 shows a block diagram of the electronic control circuit 20 and its related parts.

Reference numeral 30 is a central processing unit (hereinafter simply referred to as CI) U that inputs and operates the data output from each sensor according to a control program, and performs other processing such as controlling the operation of various devices. 31 is a read-only memory (hereinafter simply referred to as ROM) in which control programs and initial data are stored; 32 is an electronic control circuit 2;
A random access memory (hereinafter simply referred to as RAM) in which data entered manually and data necessary for arithmetic control is temporarily read and written; A backup random access memory (hereinafter simply referred to as backup RAM) is a non-volatile memory backed up by a battery to hold data necessary for operation. 34 to 37 are a variety of output signals from each sensor. 38 is a memory for each sensor. 39 is an A/D converter that converts the analog No. 13 into a digital signal; 40 is an A/D converter that converts the output signal of 1 to the CPU 30; 40 is an A/D converter that converts the analog No. 13 into a digital signal; It represents an input/output port that sends each sensor signal to the CPU 30 and outputs control signals for the multiplexer 38 and A/D converter 39 from the CPU 30.

A buffer 1 41 sends the output signal of the oxygen sensor 5 to the comparator 18 and a waveform of the output signal of the cylinder discrimination sensor 19 to the rotor 42. 43 represents a shaping circuit for shaping the rotating table sensor. The output of the knocking sensor 10 is input to an integrating circuit 44 and a peak hold circuit 45, and the output of the peak bold circuit 45 is transmitted to an input port 46 via a gate circuit 45A, and the other sensor signals are directly transmitted to Alternatively, it is sent to the CPU 30 by the input/output port 46 via the buffer 41 or the like.

Furthermore, 47.48 is connected to CP via output port 49.50.
Fuel injection valve 6 and igniter 1 are activated by the signal from U30.
Each represents a drive circuit that drives 0. Also 5
1 is a path line for signals and data, 52 is a CP
It represents a clock circuit that sends a tarok signal at predetermined intervals to the LI 30, ROM 31, ΔM 32, etc. at predetermined intervals.

Next, a control program which is a main part of this embodiment will be explained.

FIGS. 4(A) and 5 are flowcharts of the first embodiment of the present invention.

FIG. 4 (A>) is a knocking detection routine used in the A fluoride number determination routine of FIGS. 5 and 6, which will be described later. This is a vibration detection sensor, and its detection output includes not only vibrations caused by knocking in the gasoline engine 10, but also noise components such as the old name of the valve.

Therefore, in order to accurately detect the occurrence of knocking from these detection outputs, the J knocking detection routine shown in FIG. 4 (Δ) is adopted.

The processing procedure of the tree routine will be described below with reference to the timing diagram of FIG. 4(B). The figure (B) shows the case of a 6-cylinder gasoline engine as an example. The diagram shows the crank rotation angle along the horizontal axis, and the order of the cylinders in which combustion occurs and the crankshaft rotation angle from the top dead center (hereinafter simply referred to as TDC) of the cylinders.

The waveforms <a> to ((j) in the figure represent signals corresponding to the times, and the waveform (a) is the signal that corresponds to the knocking sensor 10.
(b) The waveform is the output of the knocking sensor 10 (
(a) Waveform) is the input and output of the integrating circuit 44, (C) waveform is the timing signal output from the input port 46 to the beat hold circuit 45 and gate circuit 45A, (d) waveform is The output of the knocking sensor 10 (
(a) represents the output of the peak bold circuit 45 which inputs the waveform).

As is clear from the waveform (d'), the peak hold circuit 45 is turned on at the rising point of the timing signal of the waveform (C), and is turned off at the falling point. Further, the gate circuit 45A that receives the same timing signal (C) waveform is connected so that the gate is open while the timing signal <C) waveform is at a high level.

Knocking occurs at a crank angle of 30'CΔ to 60' from the top dead center of the cylinder where combustion is being performed.
This usually occurs during the period extending to CΔ, and this is to enable signal capture to be executed only during this period.

The CPU 30 inputting the above waveform is shown in Fig. 4 (Δ).
The occurrence of knocking is detected as follows according to 70-di-ir-t.

When CI) U 30 moves to the processing of Wood Luzin, step 100 is first executed, and the output of the integration circuit 44 and the output of the peak hold circuit 45 via the gate circuit 45△ are synchronized with the rotation angle of the crankshaft. Load. That is,
The output of the integrating circuit 44 is rAJ in synchronization with the top dead center of each cylinder.
Next, the crankshaft rotating table 9 from the top dead center of each cylinder
The output from the gate circuit is taken in as rBJ in synchronization with 0' CA ((b) and (d) in Figure 4(B)).
>Reference).

Next, step 110 is executed, and the magnitude relationship between these captured information values rAJ and rBJ is determined. Here K
is a predetermined constant, which absorbs the amplification function inherent in the integrating circuit 44, the peak bold circuit 45, and the gate circuit 45Δ, and the output rBJ of the gate circuit 45A becomes
This is to determine a so-called threshold level at which it is determined that knocking occurs when a predetermined output difference exists compared to the output rAJ of the integrating circuit 44. Since the possibility of knocking occurring at the top dead center of each cylinder is extremely low, the knocking sensor 10 at this time
It is assumed that the output of the gasoline engine 1 detects vibrations other than knocking, and the knocking 10 output, which is greater than the output at the time of the engine by a predetermined multiplier (K), is detected from the crankshaft angle of 15° CΔ for a period of 90408 days. When this is detected within the range, it is determined that knocking has occurred in the gasoline engine 1. In this step 110, B<KX△
If it is determined that the knocking (
Let's go! Assuming that the value is not 1, the variable N is set to 1'0. Also, when it is determined that B≧KxA, Fu:1
It is determined that a -ng has occurred, and the process moves to the next step 130.

Step 130 uses a constant L (L>K) to determine the degree of knocking. Output B of knocking sensor 10
If B≧LxA is large, a very human-like vibration occurs at the same stage as the one that occurred in gasoline engine 1, and the next step 1
At step 40, the variable N is set to "2", and if B<LXA, the knocking is small and the process proceeds to step 150, where the variable N is set to "'1".

Based on the output processing of the knocking sensor 10 performed as described above, the A-tank number determination routine of this embodiment shown in FIG. 5 is executed. This routine goes further and not only determines the octane number, but also the determined IC.
Using the results, describe a method to prevent the occurrence of knocking by changing the maximum h1 that the exhaust temperature will allow when using fuel with a specific tank number in the gasoline engine 1. ing. This routine is interrupted by the CI U 30 for each DC of each cylinder, for example.

When the CPLJ 30 shifts to processing of this routine, step 200 is executed first. Here, the contents of the flag FA are determined. As will be explained later, the flag FA is the one that is hit at ``11'' when it is judged that the gasoline engine 1 is using low octane fuel.If the flag FA is ``1'', the next step 210 is executed. If the process from to step 213 is other than [1], step 2
20 is executed.

Steps 210 to 213 are the ignition timing control method after it is determined that low octane fuel is already being used, and as usual, in step 210, it is determined whether or not knocking is currently occurring. That is, the above-mentioned figure 4 (
The contents of the variable N written as a result of the execution of the knocking detection routine of A> are searched. If N=O, it is determined that knocking has not occurred and step 211
By advancing the current ignition timing by a predetermined amount, the gasoline engine 1 can generate higher torque and approach advance angle control with good fuel efficiency [), and in the case of N22, to suppress the occurrence of knocking. It is a predetermined amount than the current ignition timing [
Then, in step 212, the angle is retarded.

Step 213 includes steps 211 a3 and 2
In the step performed after the ignition timing control of step 12, the new ignition timing retardation amount set by the above ignition timing control is preset to the maximum retardation m01- for low octane number.
Determine whether the value is smaller than 1, and if θ
If it exceeds H, it is reset to the maximum retard amount θ1-1, and a guard process is performed to prevent execution of retard control by more than θl in any case. low octane fuel 1
'31 has low anti-knock properties and tends to cause knocking, which tends to cause damage to the gasoline engine 1. Therefore, the maximum kneading angle θ (-1 is the maximum allowable increase in exhaust temperature) for low octane. need to be delayed.

A guard is provided in this step to prevent retardation exceeding the maximum retardation amount θH in any case.

Step 220 is a determination step that is executed when it is not determined that low octane fuel is still being used, and here the content of the flag FB is determined. Flag FB is the ignition of gasoline engine 1 for high octane 1 song + 1. 'lrou is already the maximum retardation amount θ for high octane
The flag FB is set to "1" if +11J at the time of ignition has reached the maximum retard amount θL. If it is determined in this step that FB is not 11, the ignition timing control for high octane from step 221 to step 226 is executed, and if B is (1), step 230 is processed.

First, the ignition timing control for high octane number from step 221 to step 226 will be explained.

This control is almost the same as normal ignition timing control, and first, in step 221, it is determined whether or not the gasoline engine 1 is currently causing knocking, as shown in FIG. 4 (A) above. The judgment is different from the contents of the variable N obtained by the knocking detection routine. And N= rO
If J, proceed to step 222 to perform advance angle control;
If >0, the process moves to step 223.

The sub-tube 222 performs advance angle control in predetermined angle increments, and the process of this routine ends.

In step 223, the amount of retardation in the current ignition timing control is 6.
This is to judge whether there is still room for retardation compared to the maximum retardation amount θL for 3932 valence, and the maximum retardation amount OL for high octane and the current retardation amount θ. If it is determined that θ≦θL, the process moves to step 224, where a predetermined amount is added to the current retard amount of 0 to make the retard even larger, and the processing of this routine ends. On the other hand, θ〉
If it is determined that θL, step 225 is executed.

Step 225 determines that the ignition timing control has already reached the maximum d angle I port θL for bird octane, sets the aforementioned flag FB to "1", and proceeds to the next step 22.
Move on to 6.

Step 226 is to set a variable CΔ used for time measurement /j as described later to an initial value NOOJ, and the completion of this step completes the implementation of this routine.

Next, step 230 is executed when it is determined in step 220 that FB=1, that is, ignition timing control using the maximum retardation amount θL for the convex A tank number has already been executed.
The following will be explained.

In step 230, the variable CΔ set in MOOJ in step 226 is decremented by 1 degree.C1 Calculate how many times this routine has been executed since the time when the retardation reaches the maximum retardation amount θL for high octane.1c This is the next step. Then, in the next step 231, it is determined whether or not this decremented variable C△ satisfies CA>O.
I will do it.

If it is determined in step 231 that CA>O, step 232 is executed, and if CA≦0, step 234 is executed.

Step 232 is a step of determining whether the value of the variable N indicating the current knocking occurrence state set by the 1=knocking determination routine shown in the flowchart of FIG. 4(A) is N=2. If N=2, it is assumed that large knocking is occurring in the gasoline engine 1 despite the current ignition timing control using the maximum angle mθL for high octane numbers, and the variable CB for the large knocking count is incremented in step 233. Also,
If N<2, then ``no knocking has occurred, or even if GJ has occurred, it is small, and the processing of this routine ends.

Step 234, which is executed when it is determined in step 231 that CA≦0, resets the flag FB. The flag FB is set when the 04th stage of ignition is set to the maximum retard amount θL for 63932 valence as mentioned above.
If this FB is set to "1" by the process of step 220, the processes after step 230 will be forcibly executed in the next process of this routine. Therefore, after that, normal ignition timing 1
Instead of performing 1Jtllll, the variable CB is incremented every time the variable N=2 in steps 232 and 233. Therefore, the processing of the step of counting the occurrence of knocking is completed on the condition that this routine with CA≦0 has been executed 100 [11i1t'j lines, and the flag FB is reset to restart normal ignition. It's back to the 11 system 911 mode.

In the next step 235, this routine performs 10 steps as described above.
During execution 0 times, it is determined whether the contents of the argument variable acB are greater than 10 in accordance with the occurrence of large knocking. Here, if CB>10, the flag FA is set to "1" in step 236, and CB≦1
If it is 0, the CB is cleared and this routine ends.

Among the steps of this routine, steps 223, 225, 226, and 230 to 237 represent the process for determining the octane number.

Through the processing of this routine as described above, the octane number of the fuel used in gasoline 1 engine 1 can be automatically determined.

Jj, in this routine, S of '1J10 other than knocking
/N ratio, etc., if large knocking occurs in gasoline engine 1 more than 10 times while this routine is executed 100 times in a row, gasoline engine 1 uses fuel with a low octane rating. Although the method for determining whether the engine is running has been explained, the knocking frequency for determination can be set arbitrarily depending on the performance of the knocking sensor 10, the characteristics of the gasoline engine 1, etc.

Next, as one example of the above, an embodiment in which the performance of the knocking sensor 10 is considered will be described.

FIG. 6 is a flowchart in which the octane number is determined in addition to the octane number determination routine shown in FIG. 5, taking into account the rotational speed N of the gasoline engine 1 and the continuous occurrence of large knocking. As for knocking, the sensor 10 detects the vibration of the gasoline engine 1, so when the gasoline engine 1 rotates, it detects vibrations other than knocking that occur in the gasoline engine 1 due to various vibrations such as valve hitting noise. may be detected. Therefore, the condition for determining the octane number is when the rotational speed NE of the gasoline engine 1 is low to medium rotational speed (NE<4000 rpm). Furthermore, from the detection results of the knocking sensor 10, it is clear that the possibility that low octane fuel is being used is higher in cases where large knocking occurs continuously or intermittently. It is. On the other hand, in this flowchart, in consideration of these cases, a weight is applied to the occurrence of continuous large knocking, so that the octane number can be determined more accurately.

Hereinafter, each step in FIG. 6 will be explained in detail while comparing it with the first embodiment.

Each step represented by step numbers 300 to 337 is the same as step numbers 200 to 237 in the flowchart of the first embodiment shown in FIG. This is what we do.

In this routine, new alphanumeric characters are added to the step numbers, and these steps perform the following processing.

Step 320A is executed when the i■ angle suspension has already reached the maximum retard amount OL due to the ignition timing control in step 323. In the first embodiment, this step is not necessary, and the next step 225 and step 226 are immediately performed, the flag FB is let, and the variable CA is set. However, in this routine, in this step 320A, the rotation speed NE of the gasoline engine 1 is
Determine whether the rotation speed is low or medium speed, NE<400Or11
If it is 111, more accurate data can be obtained from the output of the knocking sensor 10, so the flag FB is set and steps 325 and 326 are executed only when NIE<4000 rpm. In other cases (NIE
≧4000 rpm), the processing of this routine ends.

Step 330A also involves determining the rotational speed NE of the gasoline engine 1 in the same manner as described above. This step is
This step is provided immediately before step 332 and step 333, which determines whether or not a narrow large knock has occurred in the gasoline engine 1 within the time period until the variable CA becomes 1-01. These counting processes are performed only when rotation is being performed, that is, when NE < 400 Orpm.
i The routine ends after processing step 330C without counting the large knocks.

The newly added steps from step 330B to step 330F are for weighting cases where large knocking occurs continuously or intermittently when counting large knockings. In the first embodiment, if large knocking had occurred in step 232, the variable CB was simply incremented by 1 and counted; however, in this routine, a newly added step performs the following processing. It will be done.

First, in step 332, when large knocking is detected, step 330B is executed and variable CC is incremented.

Here, the variable CC is a new number set to indicate the occurrence of large knocking. Also, check that there is no major knocking or that the rotational speed NE is 400 O.
If it is greater than or equal to rpm, this variable CC is retold in step 330C.

Step 330D determines 117 whether the variable CC incremented to 1 in step 330B is 2 or more.
i ”l. Large knocking occurs continuously (CC 2)
It is determined whether the error is occurring or is occurring intermittently (CG=1). If CC is 2, go to next step 330F; if CG=1, go to step 333J
Ru.

Step 333 is the same as in the first embodiment, and simply increments the variable CB that counts the occurrence of large knocking. However, when large knocking occurs continuously, step 330E is executed and the variable CB is incremented. It adds "2" to the contents all at once. CB for this
When large knocking occurs continuously, the content of the noise level rises rapidly, and at other times, it gradually rises or becomes stagnant. When step 333 or step 330E is executed, the processing of this routine ends.

After changing the contents of the variable CB in this way, the contents of CB and the predetermined amount are compared as in the first embodiment, and if the predetermined value is greater than the predetermined value, it is determined that the gasoline engine 1 is using fuel with a low octane number. It is to judge. In this routine, the predetermined value is set to "20" as shown in step 330F.

This is because "2" is added to the variable CB at once when large knocking occurs continuously as described in step 330F.

In order to determine that the fuel in the gasoline engine 1 is of low octane value through this routine that performs the processing as described above, the S/N ratio of the knocking sensor 10 must be high and this routine must be executed 100 times. This is when CB becomes greater than 20 due to either large knocking occurring 10 or more times in a row, or 20 or more large knocking occurring intermittently, or a combination of these.

Therefore, when comparing the first embodiment, it is possible to detect the octane number with higher precision by the knocking sensor 10, and the variable C
Since a change occurs in the increase in B, it is possible to improve the accuracy of octane number determination.

J3, in the first embodiment and the second embodiment, the maximum angle suspension θH for low octane numbers and the maximum retardation amount θL for high octane numbers.
has been explained as a fixed constant, but as in the technology used, these maximum retard angles mO11 and θ are expressed as variables related to the rotation tyNIE of the gasoline engine 1. Even if the relationship is as shown in FIG. 7, there is no change in the implementation of the present invention. In this case, the relationship θH>θL holds true for all rotational speeds NE.

[Effects of the Invention] As explained above, the octane number determination method of the present invention allows the gasoline engine, which is controlled to use fuel with a predetermined octane number, to reach the maximum retard amount in the ignition 0.1 period control. Even after retarding the engine, the knocking is still in the specified class 1!
This is a method of determining that the A-octane number is lower than the predetermined octane number when 1 or more occurs.

Therefore, the octane number of the fuel used in the gasoline engine can be automatically determined without any operation by the driver, and the driver does not feel inconvenienced in any way.

Furthermore, if the method of the present invention is used to determine the octane number and then control the gasoline engine in accordance with the octane number, no matter what kind of fuel is used in the gasoline engine, abnormal temperature rises in the exhaust gas will be avoided. prevent,
In addition to avoiding overheating, the frequency of knocking can be minimized, which greatly reduces the possibility of damage to the gasoline engine.

[Brief explanation of the drawing]

FIG. 1 is a basic flowchart of the present invention, FIG. 2 is a schematic diagram of a gasoline engine and its peripheral equipment in which an embodiment of the present invention is utilized, FIG. 3 is a block diagram of an electronic control device, and FIG. figure(
A) is a flowchart forming a part of the first embodiment and the second embodiment, FIG. 4<8) is an explanatory diagram of the process, and FIG.
Flowcharts 17-1 to 17-1 of the embodiment, FIG. 6 is a flowchart of the second embodiment, and FIG. 7 is an explanatory diagram showing an example of changes to the rotational speed for maximum retardation. 1... Gasoline engine 10... Knocking sensor 18... Rotation speed sensor 20... Electronic control circuit 30... CPU 44... Integrating circuit 45... Peak hold circuit 46... Game i・Circuit Figure 3 N07 Figure 4 (A)

Claims (1)

[Claims] In an octane number determination method for a gasoline engine in which ignition timing is controlled using a predetermined retard amount as an upper limit value in accordance with fuel of a predetermined octane number, knocking occurs at a predetermined frequency even after the ignition timing retard amount reaches the upper limit value. An octane number determination method that determines that the octane number of the fuel is lower than the predetermined octane number due to the occurrence of the above.