JPH09151777A - Fuel nature detecting device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect a nature of fuel as early as possible. SOLUTION: After leading to a prescribed cranking period (for instance, cranking rotational speed 3000rpm) (detected in S2), at each prescribed cycle (for instance, engine 1/2 turn), a rotational speed deviation ΔNe is detected, and, when an integrated value ΣDNE of this deviation (detected in S3) reads a prescribed value JDDNE or more (judged in S5), based on whether or not a number of time lapse cycles Cycl (detected in S4) is a prescribed value JDCYL or more, nature (heavy/light quality) of fuel in use in detected (S6, S7, S8). In this way, after starting operation, a fuel nature can be detected as early as possible.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improved technique for detecting the property of fuel currently used in an internal combustion engine.

[0002]

2. Description of the Related Art Conventionally, an apparatus for detecting a fuel property (a difference in vaporization rate depending on heavy and light of fuel used) and optimizing, for example, an increase correction amount of a fuel supply amount at the time of cooling in accordance with the detection result. Has been proposed (JP-A-5-1958).
40, see JP-A-4-252835).

The device disclosed in Japanese Patent Laid-Open No. 195840/1993 detects surge torque of the engine based on the rotational speed deviation and increases the amount of increase correction according to the water temperature which is set in advance with a margin. Is gradually reduced until the surge torque exceeding the allowable level is detected, so that the minimum increase correction amount (according to the fuel property) required for the fuel used at that time can be obtained. Therefore, the higher the vaporization rate of the fuel used, the lower the correction amount for increase is corrected.

However, in the above-mentioned conventional apparatus, when the amount of increase correction is suddenly reduced, there is a possibility that a large surge torque that affects drivability may be generated because the amount of increase correction is reduced below the optimum level of increase correction. The decrease correction speed of the increase correction amount cannot be increased, and therefore, it takes a comparatively long time to finally obtain the optimum level of the increase correction amount, and there is a period in which the exhaust property can be improved by the optimum increase correction amount. There is a problem that it is limited (that is, the fuel property cannot be detected early while ensuring the drivability), and the increase correction amount is corrected to the optimum level (in other words, the fuel property is detected) as soon as possible. I couldn't fully meet the demand for it.

Therefore, the applicants of the present application filed Japanese Patent Application No. 6-29.
In Japanese Patent Laid-Open No. 312-320, the time until the exhaust air-fuel ratio shows a change commensurate with the changed fuel supply amount with respect to the change in the fuel supply amount to the engine intake system (time lag).
Is affected by the difference in the wall flow forming characteristics and the evaporation characteristics due to the difference in the properties of the fuel used, so paying attention to the fact that the fuel properties can be detected by detecting the time lag. By forcibly changing the fuel supply amount stepwise and measuring the time until the air-fuel ratio change corresponding to the step change of the fuel supply amount occurs as data correlated to the fuel property (vaporization rate), We proposed a device that can detect the properties of fuel used in a short time immediately after starting.

[0006]

However, in the device disclosed in Japanese Patent Application No. 6-29312, since the air-fuel ratio of the engine intake air-fuel mixture is forcibly changed after starting, the air-fuel ratio of the engine intake air-fuel mixture is reduced. Target air-fuel ratio (eg theoretical air-fuel ratio)
Therefore, it is difficult to obtain the desired exhaust performance and operating performance, and even if the property of the fuel used can be detected in a short time immediately after the start, the property is determined after a predetermined operating state is reached after the start is completed. Since it is a configuration, it is necessary to determine the properties of the fuel used as early as possible from the start of start and to perform optimal engine control (air-fuel ratio control, ignition timing control, etc.) that matches the properties of the fuel used. It can be said that there is room for improvement, as it is not completely satisfactory.

The present invention has been made in view of such a conventional situation, and the property of the fuel used can be started from the start without deteriorating the exhaust performance and the driving performance for detecting the property of the fuel used. An object of the present invention is to provide a fuel property detecting device for an internal combustion engine, which can be detected as early as possible.

[0008]

For this reason, the fuel property detecting apparatus for an internal combustion engine according to the first aspect of the present invention is shown in FIG.
As shown in FIG. 5, a predetermined cranking timing detecting means for detecting a predetermined cranking timing, and a degree of change in the engine speed for each predetermined period from the predetermined cranking timing detected by the predetermined cranking timing detecting means are detected. Rotation speed change degree detecting means, calculated value detection means for detecting the calculated value of the rotation speed change degree for each predetermined period detected by the rotation speed change degree detecting means, and the predetermined cranking time has elapsed. A fuel property for detecting the property of the fuel used, based on the elapsed period detecting means for detecting a predetermined period, the calculated value detected by the calculated value detecting means, and the elapsed period detected by the elapsed period detecting means. And a detection means.

According to the above configuration, the degree of change in the engine rotation speed is detected for each predetermined period from the predetermined time during cranking for starting, the calculated value of the degree of change in the engine rotation speed, and the elapsed period. Since the property of the fuel used is detected on the basis of the correlation of No. 1, it is possible to detect the fuel property as early as possible from the start of starting (start of cranking).

That is, when the engine is ignited and burned during cranking, the engine speed rapidly changes, while the vaporization characteristics and the like differ due to the difference in fuel properties, which results in ignitability, startability, that is, starting start. Since the elapsed time required from (start of cranking) to complete explosion (to start complete ignition combustion) will be different, the calculated value of the degree of change in rotational speed for each predetermined period from the start of startup. By observing and the elapsed time, the fuel property can be detected with high accuracy and easily.

Although it is possible to detect the fuel property to some extent by observing only the rotational speed change degree (not the calculated value) in correspondence with the elapsed time from the start of the start, the calculated value can be detected as in the present invention. It is possible to improve the detection accuracy by using. This is because from the start to the complete explosion, for example,
Once there was an initial explosion (it will be ignited and burned for the first time after startup), ignition and combustion will not be performed for several cycles, and then
Since there is a situation where it will be ignited and burned again to the complete explosion,
It is highly possible that the fuel property is erroneously detected only by observing only the degree of rotation speed change (not the calculated value) in correspondence with the elapsed time from the start of the start, and the fuel composition is detected with high accuracy by the simple structure of the present invention. This is because it becomes difficult to improve accuracy.

According to the present invention as described above, for example, as compared with the conventional one in which the operating state is changed after the predetermined operating condition is satisfied after the completion of the start and the property of the fuel used is detected. Thus, the property of the fuel used can be detected very early, and a situation that deteriorates drivability, exhaust performance, etc. due to the detection of the fuel property can be completely avoided.

Further, according to the present invention, the fuel property can be detected early.
Then, based on the result, start-up and post-start increase
Correction coefficient K_ASAnd water temperature increase correction coefficient K_TWAnd acceleration increase correction
Number K _ACC(Then the air-fuel ratio), the fuel used at that time
If it is corrected early so that the
A positive value that can improve exhaust performance to the maximum.
A fuel ratio control device can be provided. Claim 2
In the invention, the fuel property detecting means is configured to detect the calculated value.
When the calculated value detected by the means exceeds a specified value
The elapsed period detected by the elapsed period detecting means is
Based on whether or not the fuel consumption exceeds the specified value,
It is configured to detect the property.

This makes it possible to detect the properties (heavy / light) of the fuel used with a very simple structure and quickly and with high accuracy. According to the third aspect of the invention, the predetermined value related to the elapsed period is variably set according to the temperature state. In the invention according to claim 4,
The predetermined value related to the calculated value is variably set according to the temperature condition.

According to the third and fourth aspects of the present invention, the ignition value, the startability, etc. are changed according to the change of the temperature condition such as the outside air temperature and the engine temperature, so that the calculated value and Even if the correlation with the elapsed time changes, the change in the correlation can be corrected, so that the detection accuracy of the fuel property can always be set to a desired accuracy even if the temperature state changes. . In the invention according to claim 5, the predetermined cranking time is configured as a time when the engine rotation speed during cranking reaches a predetermined rotation speed.

That is, when the fuel property is detected from the correlation between the calculated value and the elapsed time as in the present invention, for example, the degree of change in the engine speed is the speed of the starter motor (cranking speed). ) Change rate (the change rate of the starter rotation speed changes depending on the battery consumption degree), and the change rate of the starter motor rotation speed adversely affects the detection accuracy of the fuel property. Therefore, in order to eliminate this adverse effect as much as possible, for example, when a light fuel with good startability is used, the engine is started and starts to rotate by itself until it reaches a predetermined rotation speed near the low speed side (for example, 300 rpm). If the detection of the fuel property based on the degree of change in the engine rotation speed is not performed, the change in the rotation speed of the starter motor It is possible to eliminate the influence of the exhaustion degree, etc.) or the like Terri, it becomes possible to detect the fuel property with high precision while a simple configuration I following.

In a sixth aspect of the invention, the predetermined period is configured to be 1/2 engine revolution. As a result, the degree of change in the engine rotation speed is detected and calculated for each 1/2 revolution of the engine. This configuration is based on the detection limit of the degree of change in the engine rotation speed and the engine speed. This is desirable in that the degree of change detection accuracy and the fuel property detection accuracy can both be achieved. According to the seventh aspect of the invention, the degree of change in the engine rotation speed is the engine rotation speed deviation.

As a result, the fuel property can be detected with high accuracy and as quickly as possible while having a simple structure.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below.
Description will be given based on the attached drawings. In FIG. 2 showing the system configuration of the first embodiment of the present invention, air is taken into an internal combustion engine 1 from an air cleaner 2 through an intake duct 3, a throttle valve 4 and an intake manifold 5. In each branch of the intake manifold 5, a fuel injection valve 6 is provided for each cylinder. Note that the fuel injection system may be a so-called single-point fuel injection system in which one fuel injection valve supplies fuel to a plurality of cylinders, instead of each cylinder.

The fuel injection valve 6 is an electromagnetic fuel injection valve which is energized by a solenoid to open the valve, and deenergized to be closed, and the energization is controlled by a drive pulse signal from a control unit 12 which will be described later. The fuel, which is opened and pressure-fed from a fuel pump (not shown) and adjusted to a predetermined pressure by a pressure regulator, is intermittently injected and supplied to the engine 1.

A spark plug 7 is provided in each combustion chamber of the engine 1 to ignite sparks to ignite and burn the air-fuel mixture introduced into the cylinder. Exhaust gas is discharged from the engine 1 through the exhaust manifold 8, the exhaust duct 9, the catalyst 10 and the muffler 11. The control unit 12 that electronically controls the fuel supply to the engine is a CP
The fuel injection valve 6 is composed of a microcomputer including U, ROM, RAM, an A / D converter, an input / output interface, etc., receives input signals from various sensors, and performs arithmetic processing as described later. Control the operation of.

The various sensors include an intake duct 3
An air flow meter 13 is provided in the control unit 1 for outputting a signal corresponding to the intake air flow rate Q of the engine 1.
It is designed to output to 2. In addition, a crank angle sensor 14 is provided, and each reference angle position (for example, TD
The reference angle signal REF for each C) and the unit angle signal POS for each 1 ° or 2 ° are output. Then, in the control unit 12 to which these signals are input, the engine rotation speed Ne can be calculated by measuring the cycle of the reference angle signal REF or the number of generations of the unit angle signal POS within a predetermined time. Has become.

Although the water temperature sensor 15 for detecting the cooling water temperature Tw of the water jacket of the engine 1 is provided, the invention is not limited to this, and the engine temperature and the outside air temperature (or the intake air temperature) of other parts can be detected. A sensor may be provided. Here, the CPU of the microcomputer built in the control unit 12 performs arithmetic processing according to the program on the ROM to calculate the fuel injection amount (injection pulse width) Ti to the engine 1, and the fuel is injected at a predetermined injection timing. A drive pulse signal having a pulse width corresponding to the injection amount Ti (fuel supply amount) is output to the fuel injection valve 6.

The fuel injection amount Ti is the fuel injection amount Ti =
It is calculated as basic injection amount Tp × various correction coefficient Co + voltage correction amount Ts. The basic injection amount Tp is a basic injection amount determined based on the intake air flow rate Q and the engine rotation speed Ne, and the voltage correction amount Ts corresponds to an increase in the invalid injection amount due to a decrease in the battery voltage. This is the correction amount for.

Further, the various correction coefficients Co are Co =
{1 + air-fuel ratio correction coefficient K _MR + water temperature increase correction coefficient K _TW + start and after start increase correction coefficient K _AS + acceleration increase correction coefficient K
_ACC + deceleration reduction correction coefficient K _DC + ...}. The air-fuel ratio correction coefficient K _MR is a coefficient for correcting the basic injection amount Tp so as to obtain an optimum air-fuel ratio with respect to the engine rotation speed Ne and the basic injection amount Tp (engine load). _KTW increases and corrects the injection amount as the cooling water temperature Tw is lower.

Further, the starting and post-starting amount increase correction coefficient K
_AS (starting amount increase correction means) is a coefficient for increasing the fuel amount at the time of starting to secure the starting property and the drivability immediately after starting. The lower the cooling water temperature Tw at the time of starting and immediately after starting, the lower the injection amount. Is set to tend to increase, and the increase correction amount is gradually decreased at a predetermined rate after the start so that it finally becomes zero. Furthermore, the acceleration increase correction coefficient K
_{The ACC} and the deceleration reduction correction coefficient K _DC are used to increase / decrease the injection amount in order to avoid fluctuations in the air-fuel ratio during acceleration / deceleration of the engine.

Here, the request for correction of the injection amount by the various correction coefficients Co changes depending on the properties of the fuel used, especially the heavy and light (vaporization rate) of the fuel, and when using a heavy fuel with a low vaporization rate, , The startup and post-starting increase correction coefficient K _AS , the water temperature increase correction coefficient K _TW, and the acceleration increase correction coefficient K _ACC
The demand for increasing the fuel consumption due to is larger than when using a light fuel with a high vaporization rate.

Therefore, the actual amount of increase in response to the increase correction request
The correction level is insufficient, which causes the air-fuel ratio to become lean.
Cannot be started and impair the stability of engine operation.
In order to prevent
Number K_AS, Water temperature increase correction coefficient K _TWAnd acceleration increase correction coefficient K
_ACCThe initial value of, for example,
Adapted to quality fuel.

However, if the actual fuel used is a light fuel, the increase correction amount becomes excessive at the initial value,
This leads to deterioration of exhaust properties (increase in emission amount of unburned fuel, etc.). Therefore, in the control unit 12 in the present embodiment, the heavy and light fuel (vaporization rate) is detected as described below, and the start-up and post-startup increase correction coefficient K _AS and the water temperature increase are detected according to the detection result. The correction coefficient K _TW and the acceleration increase correction coefficient K _ACC are corrected to values that match the actual fuel used.

The flowchart of FIG. 3 shows the control of the fuel property (heavy and light) by the control unit 12 and the correction control of various correction coefficients based on the detection result. The functions of the predetermined cranking timing detecting means, the rotational speed change degree detecting means, the calculated value detecting means, the elapsed time detecting means, and the fuel property detecting means according to the present invention are the same as those shown in FIG.
Control unit 1 as shown in the flow chart
2 is provided as software.

Here, according to the flow chart of FIG.
The detection control of the fuel property (heavy and light) performed by the control unit 12 and the correction control of various correction coefficients based on the detection result will be described. In step (denoted as S in the figure. The same applies hereinafter) 1, it is determined whether or not various calculation processes for fuel property detection have been completed.

If the answer is NO, it is determined that the various calculation processes have not been completed and the fuel property has not yet been detected, and the process proceeds to step 3 to detect the fuel property. If YES, it is determined that the various calculation processes have been completed and the fuel property has already been detected, and the present flow ends. In step 2, crank angle sensor 1
Engine rotation speed N calculated based on the detection signal from 4
e and a predetermined value STNE are compared, and if Ne ≧ STNE, the process proceeds to step 3, and if Ne <STNE, the present flow ends.

When Ne <STNE, for example, the changing speed of the engine rotation speed Ne is the changing speed of the rotation speed (cranking rotation speed) of the starter motor (the starter rotation speed depends on the degree of battery consumption). Since the change speed is different), the accuracy of fuel property detection based on the degree of change in the engine speed Ne, which will be described later, will be adversely affected. When a light fuel of good quality is used, the engine is started and starts to rotate by itself. The rotation speed near the low speed side (predetermined value STNE, for example, 300 rp
This is because the fuel property is not detected based on the degree of change in the engine rotation speed Ne until m).

In step 3, the rotational speed change (here, the deviation ΔNe is used for explanation, but the present invention is not limited to this, a change rate or the like may be used), and Ne is used.
Integrated value ΣDNE of ΔNe after ≧ STNE (=
ΣDNE ₋₁ + ΔNe) is calculated. It should be noted that ΔNe is, for example, ½ rotation of the engine (1 at crank angle) every predetermined period.
The deviation of the rotation speed Ne changed during the rotation of 80 ° (that is, the rotation speed Ne before ½ rotation and the latest rotation speed N).
However, in some cases, it may be a deviation every 1/4 rotation, every 1/1 rotation, every 1.5 rotations, every 2 rotations, etc. You can also In step 4, the number of elapsed cycles Cycl (= Cy
cl + 1) is incremented. That is, the number of times ΔNe has been integrated is calculated. The number of elapsed cycles corresponds to the elapsed period according to the present invention.

At step 5, the integrated value ΣDNE is compared with the predetermined value JDDNE. When ΣDNE ≧ JDDNE, the process proceeds to step 6, and when ΣDNE <JDDNE, step 3 is performed until ΣDNE ≧ JDDNE.
~ The process of step 5 is repeated. In step 6, the elapsed cycle number Cycl is compared with the predetermined value JDCYL. If Cycl <JDCYL, proceed to step 7,
If Cycl ≧ JDCYL, the process proceeds to step 8.

At step 7, since Cycl <JDCYL, the integrated value ΣDN of the deviation ΔNe of the engine speed Ne after the engine speed Ne becomes equal to or higher than the predetermined value STNE.
The number of cycles Cycl until E becomes equal to or greater than the predetermined value JDDNE is relatively small, and it can be determined that the completion of the start (complete explosion) was completed in a relatively short time. Therefore, the fuel currently in use has a high vaporization rate. It is determined that the fuel is “light fuel” (see FIG. 4 etc.), and then the process proceeds to step 9.

At step 8, since Cycl ≧ JDCYL, the integrated value ΣDN of the deviation ΔNe of the engine rotation speed Ne after the engine rotation speed Ne becomes equal to or higher than the predetermined value STNE.
Since the number of cycles Cycl until E becomes equal to or greater than the predetermined value JDDNE is relatively large, it can be determined that it took a relatively long time to complete the start (complete explosion), so the fuel currently in use has a low vaporization rate. It is determined that the fuel is “heavy fuel” (see FIG. 4 etc.), and then the process proceeds to step 9.

Then, in step 9, it is detected (determined).
The fuel consumption is increased to meet the fuel properties
Correction coefficient K_ASAnd water temperature increase correction coefficient K_TWAnd acceleration increase correction
Number K _ACCEtc. are made to be corrected. In addition, the above-mentioned
In step 6, the elapsed cycle number Cycl and the predetermined value JDC
Although it is configured to compare heavy and light by comparing with YL,
For more detailed detection of the properties of the fuel used,
Cycle number Cycl and integrated value ΣDN for each of a plurality of properties
The correlation with E (see FIG. 4 etc.) is stored in advance and the
Of the elapsed cycle number Cycl and the integrated value ΣDNE
The correlation is related to which one of the previously stored correlations.
Judging whether or not it hits the fuel used more precisely
It is also possible to detect the property.

Further, since the ignition performance (the required number of cycles until the complete explosion, the required period) differs depending on the engine temperature and the outside air temperature, either one or both of the predetermined value JDDNE or the predetermined value JDCYL is set. It is preferable to variably set according to the engine temperature, the outside air temperature, etc. so that the desired fuel property detection accuracy can be obtained (see FIGS. 4 to 7).

As described above, according to this embodiment, the integrated value ΣDNE of the deviation ΔNe of the engine rotation speed Ne after the engine rotation speed Ne becomes equal to or higher than the predetermined value STNE is the predetermined value JD.
Since the property (heavy and light) of the fuel used is detected based on the level of the number of cycles Cycl (elapsed period) until it reaches DNE or more, it is possible to start as early as possible from the start of starting. It becomes possible to detect the fuel property. Therefore, for example, as compared with the conventional one that detects the property of the used fuel by changing the operating state after the predetermined operation condition is satisfied after the start, the property of the used fuel can be detected very early, and It is possible to completely avoid a situation that deteriorates drivability, exhaust performance, etc. due to the detection of the fuel property.

Further, the fuel property is detected at an early stage, and based on the result, the start-up and post-starting increase correction coefficient K _AS , the water temperature increase correction coefficient K _TW, and the acceleration increase correction coefficient K _ACC (and eventually the air-fuel ratio ), If it is corrected early so as to match the fuel used at that time, the exhaust performance and the like can be improved to the maximum extent by the correction. In the present embodiment, the integrated value ΣDNE of the deviation ΔNe of the engine rotation speed Ne after the engine rotation speed Ne becomes equal to or higher than the predetermined value STNE.
The number of cycles C until the value becomes equal to or greater than the predetermined value JDDNE
Although it has been described that the property of the used fuel is detected based on ycl (elapsed period), if the change in the rotation speed of the starter motor does not affect the fuel property detection so much, the start (cranking) is started. (In this case, the start timing becomes the predetermined cranking timing of the present invention) From the time when the integrated value ΣDNE of the deviation ΔNe of the engine speed Ne is detected and the integrated value ΣDNE becomes the predetermined value JDDNE or more Based on the cycle number Cycle (elapsed period),
It can also be configured to detect the properties of the fuel used. That is, for example, the predetermined cranking time of the present invention may be detected based on, for example, that the ignition switch is turned on.

Further, in the present embodiment, the cooling water temperature Tw is used as the temperature condition according to the present invention, but the temperature of the outside air, the fuel temperature, the temperature of the engine body such as the cylinder head or the cylinder block is used. Of course, it is also good. Moreover, time can also be used as the elapsed period. A map may be used as the calculated value detecting means.

Next, a second embodiment for detecting the property of the fuel used more finely will be described. The second embodiment is substantially the same as the system configuration of the first embodiment (FIG. 2), and the fuel property detection control performed by the control unit 12 is the first embodiment (flow chart of FIG. 3). Different from

Therefore, only the fuel property detection control performed by the control unit 12 of the second embodiment will be described here with reference to the flowchart of FIG. Note that steps 1 to 5 and step 9 of the flowchart of FIG. 3 in the first embodiment are substantially the same in the second embodiment as well, so description thereof will be omitted.

That is, in the fuel property detection control of the second embodiment, as shown in the flowchart of FIG. 8, when steps 1 to 5 of the flowchart of FIG. 3 are executed, the routine proceeds to step 6A. In step 6A, the relationship among the “elapsed cycle number Cycl”, the “water temperature Tw at the time of starting”, and the “plurality of different fuel properties” is assigned in advance 3
With reference to the dimension map (shown in the flow), the fuel property currently in use is determined based on the actual elapsed cycle number Cycl and the actual start-up water temperature Tw.

After that, the process proceeds to step 9, and as in the case of the first embodiment, the start-up and post-start-up increase correction coefficient K _AS and the water temperature increase correction coefficient K _{TW are} adjusted in accordance with the judged fuel property. The process for correcting the acceleration increase correction coefficient K _{ACC and the} like is performed, and the present flow ends. As described above, according to the second embodiment, the three-dimensional map in which the relationships among the “elapsed cycle number Cycl”, the “water temperature Tw at the time of starting”, and the “plurality of different fuel properties” are assigned in advance is used. With a simple configuration, the fuel property can be detected more finely than in the first embodiment.

In both the first embodiment and the second embodiment, when the power is turned on, as shown in FIG. 9, ΣDNE ←
The reset process of 0, Cycle ← 0 is executed, and then the flowchart of FIG. 3 and the flowchart of FIG. 8 are executed.

[0048]

As described above, according to the fuel property detecting device for an internal combustion engine according to the invention described in claim 1, the engine speed of the engine speed is changed every predetermined period from a predetermined time during cranking for starting. The degree of change is detected, and the property of the fuel used is detected based on the correlation between the calculated value of the degree of change in the engine speed and the elapsed time. It is possible to detect the fuel property as early as possible. Further, according to the present invention as described above, for example, as compared with the conventional one in which the operating condition is changed and the property of the fuel used is detected after a predetermined operating condition is satisfied after the completion of start-up, it is extremely early. In addition to being able to detect the properties of the fuel used, it is possible to completely avoid a situation that deteriorates drivability, exhaust performance, etc. due to the detection of the fuel properties.

Further, according to the present invention, the fuel property is detected at an early stage, and based on the result, the air-fuel ratio is corrected at an early stage so as to match the fuel used at that time. It is possible to provide an air-fuel ratio control device capable of maximally improving the above. According to the second aspect of the present invention, the properties (heavy / light) of the fuel used can be detected quickly and accurately with an extremely simple configuration.

According to the third and fourth aspects of the present invention, the ignition value, the startability, etc. are changed according to the change of the temperature condition such as the outside air temperature and the engine temperature, so that the calculated value and Even if the correlation with the elapsed period changes, the change in the correlation can be corrected, so that the detection accuracy of the fuel property can always be set to a desired accuracy. Claim 5
According to the invention described in (1), it is possible to eliminate the influence of the change in the rotation speed of the starter motor (the degree of consumption of the battery, etc.), and thus it is possible to detect the fuel property with high accuracy with a simple configuration. it can.

According to the sixth aspect of the present invention, the detection limit of the degree of change of the engine rotation speed and the detection accuracy of the degree of change of the engine rotation speed, that is, the detection accuracy of the fuel property are well compatible with each other. You can According to the invention described in claim 7, the fuel property can be detected with high accuracy and as quickly as possible while having a simple structure.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of the present invention.

FIG. 2 is a system schematic diagram showing the first embodiment of the present invention.

FIG. 3 is a flowchart illustrating a fuel property detection control according to the above embodiment and correction control of various correction coefficients based on the detection result.

FIG. 4 is a diagram (Tw) for explaining a difference between the cycle number Cycl (elapsed period) from the start of counting the cycle number (elapsed period) and ΣDNE due to a difference in fuel property.
= 25 ° C).

FIG. 5 is a diagram (Tw) for explaining the difference in the correlation between the number of cycles Cycl (elapsed period) from the start of counting the number of cycles (elapsed period) and ΣDNE due to the difference in fuel property.
= 10 ° C).

FIG. 6 is an example of a table for variably setting a predetermined value JDDNE based on an engine temperature (Tw), an outside air temperature, or an intake air temperature.

FIG. 7 is an example of a table for variably setting a predetermined value JDCYL based on an engine temperature (Tw), an outside air temperature, or an intake air temperature.

FIG. 8 is a flowchart illustrating a fuel property detection control of the second embodiment and correction control of various correction coefficients based on the detection result.

FIG. 9 is a flowchart illustrating processing when power is turned on.

[Explanation of symbols]

 1 Engine 12 Control unit 14 Crank angle sensor 15 Water temperature sensor

Claims (7)

[Claims] 1. A predetermined cranking timing detecting means for detecting a predetermined cranking timing, and a degree of change in engine rotational speed for each predetermined period from the predetermined cranking timing detected by the predetermined cranking timing detecting means. Rotation speed change degree detecting means, calculation value detecting means for detecting a calculation value of the change degree of the rotation speed for each predetermined period detected by the rotation speed change degree detecting means, and the predetermined cranking time has elapsed. A fuel property for detecting the property of the fuel used, based on an elapsed period detecting means for detecting a predetermined period, a calculated value detected by the calculated value detecting means, and an elapsed period detected by the elapsed period detecting means. A fuel property detection device for an internal combustion engine, comprising: a detection means. 2. The fuel property detecting means, when the calculated value detected by the calculated value detecting means is a predetermined value or more, the elapsed period detected by the elapsed period detecting means is a predetermined value or more. The fuel property detecting device for an internal combustion engine according to claim 1, wherein the property of the fuel used is detected according to whether or not the fuel is used. 3. The fuel property detecting device for an internal combustion engine according to claim 2, wherein the predetermined value relating to the elapsed period is variably set according to the temperature state. 4. The fuel property detecting device for an internal combustion engine according to claim 2, wherein the predetermined value related to the calculated value is variably set according to the temperature condition. 5. The predetermined cranking time is a time when the engine speed during cranking becomes a predetermined speed, according to any one of claims 1 to 4. Fuel property detection device for internal combustion engine. 6. The fuel property detection device for an internal combustion engine according to claim 1, wherein the predetermined period is 1/2 rotation of the engine. 7. The method according to claim 1, wherein the degree of change of the engine speed is an engine speed deviation.
5. A fuel property detection device for an internal combustion engine according to any one of 1.