JPS61197744A - Method of estimating knocking resistant properties of fuel - Google Patents

Abstract

PURPOSE:To enable control of an internal combustion engine to an optimum state from right the starting, by a method wherein, even when fuel is fed during stop of the internal-combustion engine, knocking resistance properties value of fuel is estimated through effective utilization of a value learnt before. CONSTITUTION:A fuel amount of a gasoline engine 1 detected by a fuel sender gauge 21 attached to a fuel tank 22 is read in an ECU 20. A deviation between the fuel amount and a fuel amount stored in a backup RAM of CPU 20 and right before preceding stop is determined. When the deviation is higher than zero, knocking resistant properties value of current fuel is estimated by a given formula from a knocking resistant properties value, stored in a backup RAM of the ECU 20 learnt till a preceding time, a knocking resistant prioperties value, responding to lowermost octane value in gasoline on a market, and each fuel amount. Based on the knocking resistant properties value, a lead angle control range of ignition time control, within which knock control is performed, is set.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for estimating the anti-knocking characteristic value of a fuel, and in particular to a method for estimating the anti-knocking characteristic value of a fuel at the time of starting an internal combustion engine. This invention relates to a method for estimating knocking characteristic values.

[Prior art] In recent years, the use of unleaded gasoline with a low octane number in internal combustion engines has increased, reflecting social demands regarding lead pollution.However, there is also a demand for efficient operation of internal combustion engines. Recently, fuels with various octane numbers have come into use, such as the development of unleaded, high-octane gasoline. Therefore, it is necessary to change the control characteristics of the internal combustion engine depending on the octane number of the fuel used.

Although it is necessary to operate with a relatively advanced ignition timing, when using high-octane gasoline, higher output torque can be obtained by operating with a relatively advanced ignition timing. Furthermore, depending on the case, the air-fuel ratio may be controlled depending on the octane number.

Therefore, in order to switch such control according to the octane number of the fuel used in the internal combustion engine, conventional methods have been used to detect the operating state of the internal combustion engine, for example, the occurrence of knocking, and to memorize the ignition timing at that point. By using this method, the anti-knocking characteristic value based on the octane number of the fuel is learned, learned, and estimated, and the internal combustion engine is controlled based on the combustion. □ [Problems to be Solved by the Invention] However, even when learning the anti-knocking characteristic values of fuels, the following problems still remain.

(1) Although it is possible to learn the anti-knocking characteristic value of fuel and memorize the value of this anti-knocking characteristic value, once the internal combustion engine is stopped, it is possible to learn the value of the anti-knocking characteristic value. It is possible that fuel will be added. If the fuel is high octane (IL) when the anti-knocking characteristic value is learned
If the supplied fuel is a low-octane fuel, controlling the ignition timing etc. using the previously learned anti-knot characteristic value will change the anti-knock characteristic value of the fuel currently in use. Until learning is completed, knocking occurs frequently, which adversely affects the internal combustion engine.

(2) Therefore, when the internal combustion engine is stopped, the next time it is started, the learned anti-knotting characteristic value is not used, but the octane number of the fuel is assumed to be the lowest, and the ignition timing control etc. are performed from there. A control method is used in which the anti-knocking characteristic value is learned again.
Ru. In this case, -1 When restarting when high octane fuel is used and has not been refilled, or when high octane fuel is being used continuously, the learning of the fuel's anti-knocking characteristic value may be delayed. Until the project was completed, there were problems in that the full potential of the internal combustion engine could not be exploited and fuel efficiency could not be maximized.

Therefore, the present invention has been made for the purpose of proposing a suitable method for estimating the anti-knocking characteristic value of fuel. The anti-knocking characteristic value of the fuel is estimated using the value of 1. 5. The purpose of the present invention is to propose a method for estimating the anti-knocking characteristic value of fuel, which enables optimal control of the internal combustion engine immediately after starting.

l drunkenness L [Means to solve the problem].

In order to achieve the above object, the present invention solves the above problems.
We adopted the following configuration as a means to achieve this. That is, as shown in FIG.

In a method for estimating the anti-knocking characteristic value of fuel for an internal combustion engine, estimating the anti-knocking characteristic value of the fuel used based on the operating state of the internal combustion engine (Step P1),
.

Memorize the knock resistance value and residual fuel amount that were learned just before stopping the internal combustion engine (Step P2), detect the fuel amount when starting the internal combustion engine (Step P3), and replenish the fuel while the engine is stopped. If it is determined that the
4) determines the anti-knocking characteristic of the fuel from the stored anti-knocking characteristic value and residual fuel amount, the detected starting fuel amount and a predetermined anti-knocking characteristic value lower than the anti-knocking characteristic value. Test the value (step ps
This is the structure of the method for estimating the anti-knocking characteristic value of fuel, which is characterized by the following.

The operating state of the internal combustion engine used for learning the anti-knocking characteristic value of fuel is, for example, the ignition timing at which knocking occurs in ignition timing control that uses a knock sensor to control the ignition timing. and the engine speed and load conditions at that time.

Determining whether or not the fuel supply was excessive during the stop □ (Sugetsubu P
4) can be performed by storing the output signal of the fuel amount detection means, for example, a level gauge, and comparing the output signals. At this time, in consideration of the detection accuracy of the fuel amount detection means used, it is also preferable to provide a predetermined width for the judgment.

In addition, as a level gauge, a type of fuel gauge whose resistance value changes depending on the amount of fuel (such as a fuel sender gauge),
Alternatively, various methods such as a liquid level gauge using ultrasonic waves can be considered.

Estimating the knocking resistance characteristic value of the fuel (step P5) is as follows:
Anti-knocking characteristic value OG and residual fuel amount vfO that have been learned up to the time of stopping the internal combustion engine, and fuel ff1 at the time of starting
It can also be determined, for example, as an average value from Vf and a predetermined anti-knocking characteristic 1i0 that is lower than the learned anti-knocking characteristic value OG. That is, the estimated anti-knocking characteristic value.

n is On= (OLX (Vf-Vfo)+0GxVfo)
/Vf ・11). In this case, the anti-knocking characteristic value of the fuel mixed with different types of fuels may not necessarily be the average value, and in addition, weighting coefficients of 1 and 2 are prepared in advance to give the predetermined anti-knocking characteristic of formula (1). It is also preferable to multiply the value OL and the learned anti-knocking characteristic value OG, respectively.

Note that a predetermined anti-knocking characteristic value OL lower than the learned anti-knocking characteristic value OG can be commercially available.

[Operations] The method for estimating anti-knocking characteristic values of fuel according to the present invention having the above configuration determines whether or not fuel has been refilled while the internal combustion engine is stopped, and when refueling has occurred, the refilled fuel Currently, the anti-knocking characteristic value is set as a predetermined anti-knocking characteristic value lower than the learned anti-knocking characteristic value.
This is to estimate the anti-knocking characteristic value of the fuel in the fuel tank. Therefore, whereas in the past, learning was performed from the lowest anti-knocking characteristic value each time at startup,
The previously learned anti-knocking characteristic value when there is no fuel replenishment, and the estimated anti-knocking characteristic value when there is refueling, can be used to control the internal combustion engine immediately after starting.

[Example] Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 2 shows an internal combustion engine in which ignition timing is controlled by a microcomputer as an embodiment of the present invention. In the figure, 1 is a gasoline engine, and 1
0 is a knock sensor attached to the cylinder block 15 of the gasoline engine 1. The knock sensor 10 is a well-known device that is composed of, for example, a piezoelectric element or an electromagnetic element, and converts mechanical vibrations into electrical amplitude fluctuations.

The distributor 17 is provided with crank angle sensors 18 and 19. The crank angle sensor 18 generates 24 pulses each time the distributor shaft rotates, ie, every 30 degrees of crank angle. The crank angle sensor 19 is for cylinder discrimination, and is used every time the distributor shaft makes one revolution, that is, every two revolutions of the crankshaft (72
For example, one pulse is generated every 0' CA) at a position slightly before the compression top dead center of the first cylinder. Knock sensor 1
The electrical signals from the 0° and crank angle sensors 18 and 19 are sent to an electronic control unit (ECU>20).

Further, 21 is attached to the fuel tank 22 and the fuel amount Vf
This is a fuel sender gauge that serves as a fuel amount detection means. This signal is also sent to ECtJ20. Roughly speaking, a voltage signal corresponding to the intake air flow rate Q of the engine is sent to the ECLJ 20 from an air flow sensor 24 provided in the intake passage 23 of the engine. On the other hand, the ECLI 20 outputs an extreme signal to the igniter 26, which causes the igniter 26 to control the primary current of the ignition coil 28 intermittently. The high voltage current generated by the ignition coil 28 is sent to the ignition plug 30 of each cylinder via the distributor 17, and as a result, an ignition spark is formed at the ignition timing according to the ignition signal.

The gasoline engine 1 is provided with a cooling water temperature sensor 33 that detects the cooling water temperature, an 02 sensor 34 that detects the oxygen concentration in exhaust gas, and the like. ECtJ20
uses these operating state parameters to perform, for example, fuel injection control that determines the fuel injection amount and controls the fuel injection valve 36, air-fuel ratio control, etc., but these are not directly related to the present invention. Therefore, we will only briefly touch upon it in the following explanation.

FIG. 3 shows an example of the configuration of the ECU 20 shown in FIG. The voltage signal from the airflow sensor 24 is sent to the buffer 4
0 to an analog multiplexer (MPX) 42, selected according to instructions from a central processing unit (CPU) 43, and applied to an analog-to-digital (A/D) converter 44. The input data representing the intake air flow rate Q converted into a binary signal by the A/D converter 44 is:
It is taken into the CPU 43 via the input/output port 46.

Similarly, feel sender gauge 21. The signal from the cooling water temperature sensor 33 is also configured to be input via buffers 48 and 49.

The pulses from the crank angle sensor 18 for every 70° crank angle and the pulses for every 720° crank angle from the crank angle sensor 19 are rectangularly shaped in the waveform shaping circuit 53 and then input into the microcomputer via the input port 56. be taken in. The output signal of the knock sensor 10 is passed through an input circuit 58 consisting of a buffer that performs impedance conversion and a bandpass filter whose passband is a frequency band specific to non-king (7 to 8K>). After being sent to the /D converter 59 and converted into a binary signal, it is taken into the microcomputer via the input port 56.

Note that the output signal from the 02 Yancer 34 is inputted via the buffer 60 and then binarized as a lean/rich signal by the comparator 62 and taken in via the input port 56.

On the other hand, the fuel injection valve 36 is controlled through the internal circuit 66 of the CPU 43, and the i-control of the igniter 26 is performed through another output port lower and drive circuit 68, and fuel injection amount control 9 ignition timing control is performed, respectively. .

In addition to the above-mentioned circuits and elements, the ECU 20 includes a dedicated memory (ROM > 71) that stores control programs in advance, and a temporary storage memory (R) that temporarily reads and writes data, etc.
AM>73, a backup RAM 75 that receives battery backup and stores data even after the key switch is turned off, a CLOCK 77 that supplies a reference clock to the entire ECLI 20, and a CPU 43. ROM71. R.A.
M73. Backup RAM75. Output port 46
, input port 56. It is configured to include a bus 79 for interconnecting the output port 4.67 and others, and executes the following control. .

FIG. 4 is a flowchart showing the control executed in this embodiment, and in each step, the following processing/determination, etc. are performed.

Step 100: Read the fuel ωVf of the gasoline engine 1 inspected by the fuel sender gauge 21.

Step 110: Fuel amount Vf and backup RAM75
The amount of fuel stored in Vfo just before the gasoline engine was stopped last time,! Find the deviation Vc of :.

Step 120: Determine whether the deviation VC is greater than zero.

Step 130: Current anti-knocking characteristic value Qn of fuel
is set as the anti-knocking characteristic value OG learned previously and stored in the backup RAM 75.

3 step 140: Current fuel anti-knocking characteristic value Qn
is estimated using the following equation (2).

0n=(kl・0L−VC102・OG・Vfo)/V
f -... (2>Here, 1. and 2 are weighted parameters predetermined to obtain the average value,
OL each refers to the anti-knocking characteristic value corresponding to the lowest octane number in the octane number range of commercially available gasoline used in internal combustion engines. Therefore, the estimation of octane number by the above formula (2) is:
If the fuel replenished during the stoppage was Ganlin with the lowest octane rating, this means that the anti-knocking characteristic value of the current fuel is estimated to be on the safest side.

Step 150: Set 0 in the advance angle control range of ignition timing control for performing knock control based on the anti-knocking characteristic value On.

Step 160: Perform ignition advance control as well-known knock control in the advance angle control range Δθ.

Step 170: It is determined whether the current operating state of the gasoline engine 1 is within the learning range of the anti-knocking characteristic value of the fuel. The learning area may be, for example, the entire operating range in which knock control is performed, or it may be a part of the operating range in which the occurrence of knocking can be detected extremely reliably. Learning of the value will be performed in this operating state, and this will be determined.

Step 180: The anti-knocking characteristic value OG is learned from the advance angle value for ignition timing control for a predetermined operating state of the gasoline engine 1, and updated.

Step 190: Determine whether learning is completed. Knock control by ignition timing control is performed by controlling ignition timing based on detection of knocking. Since the advance value of the knock limit differs depending on the operating conditions such as the load and rotation speed of the gasoline engine 1, knock control is performed at several points under different operating conditions, and the anti-knocking characteristic value of the fuel is learned. Learning is complete when stable results are obtained.

Step 200: The learned anti-knocking characteristic value OG of the fuel is thereafter processed to become the anti-knocking characteristic value Qn used for knock control and the like.

Step 210: Read fuel ff1Vf.

Step 220: Processing is performed to set the fuel amount Vf to the fuel amount fo for storage. That is, the remaining amount of fuel is updated.

This control routine consisting of the above steps starts from step 100 when the gasoline engine 1 is started. First, step 100 to step 120
Based on the current fuel amount Vf detected by the fuel sender gauge 21 and the fuel amount VfO stored immediately before the gasoline engine 1 was stopped last time, it is determined whether refueling was performed while the gasoline engine 1 was stopped. Make a judgment as to whether or not. When refueling is not being performed, that is, when the judgment at step 120 is rNOJ, the anti-knocking characteristic value OG learned the last time the gasoline engine 1 was operated is used as the anti-knocking characteristic value On in the following control. Perform the setting process (Step 1)
30), while when fuel is refilled (step 120)
When the determination is rYEsJ), the anti-knocking characteristic value Qn is estimated using the above equation (2) (step 140).
).

After either of steps 130 and 140 are executed, in steps 150 and 160, the anti-knocking characteristic value Qn
Based on this, knock control is performed by advancing the ignition timing, and in step 170 it is determined whether the operating state of the gasoline engine 1 is within the learning range. If it is determined that it is in the learning area, the anti-knocking characteristic value is learned from the advance angle value determined by the knock control, and the value of the anti-knocking characteristic value OG is updated (purchase step 180). In the subsequent step 190, it is determined whether or not learning of the anti-knocking characteristic value is considered to be completed, that is, one set of learning is performed in a plurality of operating states of the gasoline engine 1, and the learned anti-knocking characteristic value is not caused by disturbances such as noise. Determine whether the value has been learned as a stable value. If the learning can be considered complete, a process is performed in which the learned anti-knocking characteristic value OG is set to be used as the anti-knocking characteristic value On in subsequent knock control, etc. (step 200) Step 17
When it is determined in step 0 that the operating state of the gasoline engine 1 is not in the learning range, or when it is determined in step 190 that learning is not completed, or after step 200 is completed, the process proceeds to step 210, The fuel amount Vf is read again, and in the following step 220, the backup RAM 7 is
A process of updating the pre-stop fuel amount Vfo stored in 5 is performed.

After the above processing, the process returns to step 150 and the steps 150 to 210 described above are repeatedly executed.

In this embodiment configured as described above, if fuel is refilled while the gasoline engine 1 is stopped, the refilled fuel is regarded as the fuel with the lowest octane number, and the fuel tank 22 is Anti-knocking estimates the anti-knocking characteristic value OG of Ganrin within the engine and uses it for subsequent knock control, while if there is no refueling, the previously learned anti-knocking characteristic value OG is directly used for knock control, etc. It is configured to be used as a characteristic value Qn. Therefore, if there is a fuel replenishment, the
Instead of assuming that the knocking resistance characteristic value of the fuel is the lowest and starting knock control by controlling the ignition timing from there, as in the past, the knocking resistance characteristic value is estimated as an average value using a weighting parameter, and knock control is started from there. Control etc. can be started. Further, if fuel is not refilled, the previously learned anti-knocking characteristic value can be used to perform optimal ignition timing control from the beginning. As a result, according to this embodiment, the gasoline engine 1
Ignition timing control after starting the engine can be started from a more advanced side than before without compromising safety. Therefore, the output is improved and the fuel consumption is also improved.

There is also a method of manually switching the octane number, that is, inputting a discrimination signal for high octane fuel or low octane fuel into the ECU using a manual changeover switch, etc., and selecting whether control for high octane fuel or control for low octane fuel is performed. Compared to the so-called fuel switch method, it also has the advantage of being able to restore proper ignition timing control according to the octane number in a short time. - Although one embodiment of the present invention has been described above using knock control based on ignition timing control, the present invention is not limited to this embodiment in any way. It is also suitable to apply it to a control system. In addition, when calculating the expected fuel consumption in a system that displays travel and distance based on the remaining fuel amount, the fuel efficiency of a fuel having an anti-knocking characteristic value estimated by the method for estimating the anti-knocking characteristic value of a fuel of the present invention is 1.5. Various applications are also possible, such as use for precise correction of air-fuel ratio control based on the anti-knocking characteristic value of fuel.

As detailed above, according to the method for estimating the anti-knocking characteristic value of fuel according to the present invention, even if fuel is refilled while the internal combustion engine is stopped, the engine can be refilled without compromising safety. This provides an excellent effect in that the anti-knocking characteristic value of the fuel immediately after starting the internal combustion engine can be estimated as a value close to the actual anti-knocking characteristic value. Therefore, compared to the conventional case where control is performed by assuming that the fuel has the lowest octane number, the time required for transient and transitional control is reduced to 100%, which improves output as well as fuel efficiency. A secondary effect can also be obtained.

[Brief explanation of drawings]

FIG. 1 is a basic configuration diagram of the present invention, FIG. 2 is a schematic configuration diagram showing the configuration of a gasoline engine in which knock control is performed and its peripheral equipment as an embodiment of the present invention, and FIG. FIG. 4, which is an electrical configuration diagram centered on the ECLJ 20, is a flowchart showing a control example in the same embodiment. 1... Gasoline engine 10... Knock sensor 18... Crank angle sensor 20... ECtJ 21... Fuel sender gauge 24... Air flow sensor 26... Igniter 30... Spark plug 36 ...Fuel injection valve

Claims (1)

[Scope of Claims] 1. In a method for estimating the anti-knocking characteristic value of fuel for an internal combustion engine, which learns the anti-knocking characteristic value of the fuel used based on the operating state of the internal combustion engine, the anti-knocking characteristic value learned immediately before the internal combustion engine is stopped. The value and residual fuel amount are memorized, and when the internal combustion engine is next started, the fuel amount is detected, and if it is determined that fuel has been replenished while the engine is stopped, the memorized anti-knocking characteristic value and Anti-knocking characteristic value of the fuel is estimated from the residual fuel amount, the detected starting fuel amount, and a predetermined anti-knocking characteristic value lower than the anti-knocking characteristic value. Estimation method. 2. The anti-knocking characteristic value estimation method of fuel according to claim 1, wherein the learning of the anti-knocking characteristic value is performed based on the ignition timing of the internal combustion engine.