JPH09144591A - Fuel property detection device for internal combustion engine - Google Patents

Abstract

(57) 【Abstract】 PROBLEM TO BE SOLVED: To detect the property of fuel at high speed and with high accuracy. SOLUTION: The indicated mean effective pressure Pi is detected based on the in-cylinder pressure detection signal of an in-cylinder pressure sensor 16 from the start (cranking) start (detected in S1), and the number of injections (the number of operation cycles) i from the start of the start is determined. When the predetermined value HANN is reached (S
5), based on whether or not the calculated value of the indicated mean effective pressure Pi, for example, the integrated value Pis (calculated in S4), is greater than or equal to a predetermined value HANPi, the property (heavy or light) of the fuel used is detected. Therefore, the fuel property can be detected as early as possible from the start of the start.

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).
No. 40). The device disclosed in Japanese Patent Laid-Open No. 5-195840 detects surge torque of the engine based on the in-cylinder pressure, and provides an increase correction amount corresponding to a water temperature that is set in advance with a margin to an allowable level. By gradually reducing the amount of correction until a surge torque exceeding the limit is detected, the minimum amount of increase correction (depending on the fuel properties) required for the fuel used at that time can be obtained. The higher the vaporization rate of the fuel, the lower the correction amount for increase will be corrected.

However, in the above-mentioned conventional apparatus, when the amount of increase correction is sharply 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 applicant 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.

[0005]

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 though the property of the fuel used can be detected in a short time immediately after the start, the property is determined after the start. It is not possible to completely satisfy the requirement to determine the properties of the fuel used as early as possible and to perform optimal engine control (air-fuel ratio control, ignition timing control, etc.) that matches the properties of the fuel used, and this is an improvement. It can be said that there is room for

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.

[0007]

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, the engine start start condition detection means for detecting the engine start start condition, the elapsed time detection means for detecting the elapsed time after the engine start start condition is detected, and the in-cylinder pressure detection means for detecting the in-cylinder pressure of the engine. And an in-cylinder pressure information detected by the in-cylinder pressure cycle information detecting means for detecting in-cylinder pressure information for each predetermined operation cycle based on the in-cylinder pressure detected by the in-cylinder pressure detecting means. In-cylinder pressure information calculation means, the elapsed time after the engine start start condition is detected, and the calculated value of the in-cylinder pressure information calculated by the in-cylinder pressure information calculation means until the elapsed time after the engine start start condition is detected. And a fuel property detecting means for detecting the property of the fuel used.

According to the above configuration, for example, the in-cylinder pressure or the indicated mean effective pressure (from the cranking start) or the like (which corresponds to the in-cylinder pressure information) is detected, and the detected in-cylinder pressure or the indicated mean is detected. Since the property of the fuel used is detected based on the level of the calculated value of the effective pressure (for example, the integrated value) at the time when a predetermined time (or a predetermined operation cycle) has elapsed, With a simple configuration, the fuel property can be detected with high accuracy as early as possible after the start of starting.

That is, the vaporization characteristics and the like differ depending on the difference in fuel properties, which results in the ignitability and startability (the time required from the start to the complete explosion (complete ignition combustion is performed) (the number of operating cycles)). ], Etc. will be different. Therefore, if the calculated value (for example, integrated value) of the in-cylinder pressure information is observed in correspondence with the time from the start of operation (the number of operating cycles), the fuel property can be determined accurately and easily. It can be detected. In addition, in-cylinder pressure information (calculated value that is not an integrated value) is associated with the time from the start of startup (the number of operating cycles).
Although the fuel property can be detected by observing, the detection accuracy can be improved by using the integrated value. This is because from the start to the complete explosion, for example, once there is an initial explosion (the ignition and combustion occur for the first time after starting), the ignition and combustion are not performed for several operating cycles, and then the ignition and combustion are performed again. Since there is a situation that can lead to an explosion, just by observing the cylinder pressure information (calculated value that is not an integrated value) in correspondence with the time (starting cycle number) from the start of startup, it can be detected quickly and with high accuracy with an easy configuration. This is because it is 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 a predetermined operating condition is satisfied after starting and the property of the fuel used is detected, This makes it possible to detect the properties of the fuel used very early, and to completely avoid the situation of deteriorating drivability, exhaust performance, etc. due to the detection of the fuel properties.

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 detection means is provided with an engine start start condition.
When the elapsed time after the detection of the case reaches the predetermined elapsed time,
Of the in-cylinder pressure information calculated by the in-cylinder pressure information calculating means.
Based on whether the calculated value is greater than or equal to the specified value,
It was configured to detect the properties (heavy / light) of the fuel for use.

This makes it possible to detect the properties (heavy / light) of the fuel used with a simple structure and quickly and with high accuracy. According to the third aspect of the invention, the predetermined elapsed time is variably set according to the temperature state.

In the invention according to claim 4, the predetermined value is variably set according to the temperature state. According to the invention described in claims 3 and 4,
Even if the in-cylinder pressure information changes due to changes in the intake air state (temperature and density) according to changes in the temperature conditions such as the outside air temperature and engine temperature, or the ignition characteristics and startability change according to the temperature conditions. However, since it is possible to suppress a decrease in the detection accuracy of the fuel property due to these changes, it is possible to always make the detection accuracy of the fuel property a desired accuracy. In the invention according to claim 5, the elapsed time is the number of operation cycles.

That is, if the fuel property is detected from the correlation between the elapsed time and the calculated value, for example, the rotation speed of the starter motor during starting (cranking) (cranking rotation speed) depending on the degree of battery consumption. And the number of operating cycles (calculated value of in-cylinder pressure information) is different even for the same elapsed time, resulting in deviation from the true correlation. If the fuel property is detected from the correlation between the number of operating cycles and the calculated value of the in-cylinder pressure information, the fuel property is detected from the correlation between the elapsed time and the calculated value. Since the influence of the degree of consumption can be eliminated, the fuel property can be detected with high accuracy while simplifying the configuration.

According to a sixth aspect of the invention, the number of operating cycles is detected based on the number of injections of the fuel injection valve. That is, the number of operating cycles can be detected based on the crank angle signal, the number of ignitions, the number of opening / closing of intake / exhaust valves, and the like. Even if there is no possibility that combustion will occur and fuel will not be injected at all, the number of operating cycles may be counted up.Therefore, there is a possibility that the detection accuracy of the fuel property may decrease. ,
If the number of operating cycles is detected based on the number of injections of the fuel injection valve, the above-mentioned fear can be avoided, and thus the accuracy of detecting the fuel property can be maintained high. .

[0016]

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. Referring to FIG. 2 showing an embodiment of the present invention, an internal combustion engine 1 includes an air cleaner 2, an intake duct 3, a throttle valve 4 and an intake manifold 5.
Air is sucked in through. 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 close the valve. The fuel injection valve 6 is energized by a drive pulse signal from a control unit 12 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. Further, each of the spark plugs 7 has an actual opening 6 as a cylinder pressure detecting means according to the present invention.
An in-cylinder pressure sensor 16 of the type mounted as a washer of the spark plug 7 as disclosed in Japanese Patent Laid-Open No. 3-17432 is provided so that the in-cylinder pressure P can be detected for each cylinder (or for a specific cylinder). ing. In-cylinder pressure sensor 16
Is configured to include a ring-shaped piezoelectric element and an electrode, and is sandwiched between the spark plug 7 and the cylinder head. The in-cylinder pressure sensor 16 may be of a type that is mounted as a washer of the spark plug 7 as described above, or may be of a type that directly detects the in-cylinder pressure by directly exposing the sensor section to the combustion chamber. .

By the way, in this embodiment, a key switch 17 is provided, and a signal indicating the key position of the key switch 17 is input to the control unit 12.
In the control unit 12, the key switch 17
The engine start (cranking) start is detected based on that the key position of is set to the start position and the key position of the key switch 17 is changed from the start position to the ON position (start signal OFF). Complete explosion) completion (cranking end) can be detected.

The control unit 12 for electronically controlling the fuel supply to the engine includes a CPU, ROM, RAM,
It is composed of a microcomputer including an A / D converter, an input / output interface, etc., receives input signals from various sensors, performs arithmetic processing as described later, and controls the operation of the fuel injection valve 6. As the various sensors,
An air flow meter 13 is provided in the intake duct 3 and outputs a signal according to the intake air flow rate Q of the engine 1 to the control unit 12.

A crank angle sensor 14 is provided to output a reference angle signal REF for each reference angular position (for example, for each TDC) and a unit angle signal POS for each 1 ° or 2 °. Here, the engine rotation speed Ne can be calculated by measuring the cycle of the reference angle signal REF or the number of occurrences of the unit angle signal POS within a predetermined time.

Although the water temperature sensor 15 for detecting the cooling water temperature Tw of the water jacket of the engine 1 is provided, the present invention is not limited to this, and a sensor capable of detecting the engine temperature and the outside air temperature of other parts is provided. May be. 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 obtained by: fuel injection amount Ti = basic injection amount Tp × variable correction coefficient Co +
It is calculated as the 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, particularly the heavy or light quality (vaporization rate) of the fuel, and when a heavy fuel having a low vaporization rate is used. , 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 fuel property (heavy and light) detection by the control unit 12 and the correction control of various correction coefficients based on the detection result. It should be noted that the functions of the engine start condition detecting means, the elapsed time detecting means, the in-cylinder pressure cycle information detecting means, the in-cylinder pressure information calculating 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 (S is shown in the figure, the same applies hereinafter) 1, the key switch 1
It is determined whether or not the key position 7 is set to the start position (ignition ON), that is, whether or not the starting start condition is satisfied. It should be noted that if the start of start (start of cranking or start of ignition) can be detected, it may be detected by another method. If YES, the process proceeds to step 2, and if NO, the present flow ends.

In step 2, it is judged whether or not various calculation processes for detecting the fuel property have been completed. If 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 3, the injection number counter i of the predetermined cylinder is incremented (i = i + 1). The number of injections may be the number of ignitions or the number of opening / closing of the intake / exhaust valve, but if the number of ignitions or the number of opening / closing of the intake / exhaust valve is used, fuel may not be supplied and combustion may occur at all. Since there is a fear that the count value may be increased even when there is no fuel injection, it is preferable to set the number of injections as in the present embodiment from the viewpoint of the detection accuracy of the fuel property.

In step 4, the predetermined cylinder in a predetermined crank angle section (preferably including the combustion stroke) in one operation cycle measured while the injection number counter i is incremented in step 3 is selected. The indicated mean effective pressure Pi is calculated, and these are sequentially integrated to calculate an integrated value Pis (Pis = Pis + Pi). The cylinder pressure sensor 1
The value and maximum value (so-called Pmax) of the in-cylinder pressure P detected at 6 at a predetermined crank angle (for example, the compression top dead center position) are
It is also possible to use it in place of the Pi. Note that the average value of several operation cycles may be integrated instead of being limited to one operation cycle.

In step 5, the injection number counter i incremented in step 3, the predetermined value HANN,
Compare. When i ≧ HANN, the process proceeds to step 6. If i <HANN, repeat until i ≧ HANN. In step 6, the integrated value Pis is compared with a predetermined value HANPi. If Pis ≧ HANPi, go to step 7. If Pis <HANPi,
Go to step 8.

In step 7, since the integrated value Pis of the indicated mean effective pressure Pi when the number of fuel injections reaches a predetermined number from the start is equal to or higher than the predetermined value HANPi, the start can be performed in a relatively short time (complete. Since it can be determined that the fuel has been used (explosion), it is determined that the fuel currently in use has a high vaporization rate and is “light fuel” (see FIG. 4, etc.), and then the process proceeds to step 9. In step 8, the integrated value Pis of the indicated mean effective pressure Pi from the start to the predetermined number of fuel injections is the predetermined value H.
Since it is smaller than ANPi, it can be judged that it took a relatively long time to start (complete explosion), so the fuel currently in use is
It is determined that the vaporization rate is low and 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 integrated value Pis and the predetermined value HANPi
Although it was configured to distinguish heavy and light by comparing and,
If you want to precisely detect the properties of the fuel used, select multiple
Correlation between the number of injections and the integrated value Pis for each property of
Etc.) in advance and based on the correlation.
It is also possible to finely detect the properties of the fuel used.
is there.

Further, the in-cylinder pressure P, which is generated when the intake air temperature and the like differ depending on the engine temperature and the outside air temperature, and hence the integrated value Pi
Since the value of s also differs, and the ignition performance (time until complete explosion) varies depending on the engine temperature and the outside air temperature, the predetermined value HANN or the predetermined value HA
It is preferable to variably set one or both values of NPi according to the engine temperature, the outside air temperature, etc. so that the desired fuel property detection accuracy can be obtained (FIG. 4 to FIG.
(See FIG. 7).

As described above, according to the present embodiment, the in-cylinder pressure or the indicated mean effective pressure (in other words, in-cylinder pressure information) is detected from the start of starting (from the start of cranking), and the detected in-cylinder pressure or the in-illustration is shown. It is possible to detect the properties (heavy and light) of the fuel used based on the level at which the accumulated value of the average effective pressure has reached a prescribed cycle (or prescribed time), so it can be started from the start. It is possible to detect the fuel property as early as possible. 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 starting and post-starting increase correction coefficient K _AS , the water temperature increase correction coefficient K _TW, and the acceleration increase correction coefficient K _ACC are used. If it is corrected early so as to comply with, the exhaust performance and the like can be maximally improved by the correction. Note that, for example, in order to secure the accuracy of detecting the in-cylinder pressure of the in-cylinder pressure sensor 16 (correction of zero drift), the start condition is satisfied after a few cycles (or a short fixed time) from the start of the start, and then the in-cylinder pressure or the indicated average is satisfied. The effective fuel is detected, and based on the level at which the integrated value of the detected in-cylinder pressure or the indicated average effective pressure is at a predetermined cycle (or a predetermined time) after the start condition is satisfied, The property (heavy / light) of may be detected.

Further, in the case where the fuel property is detected from the correlation between the elapsed time and the integrated value, the rotation speed (cranking rotation speed) of the starter motor during start-up depends on, for example, the degree of battery consumption. Differently, the number of operating cycles (integrated value of in-cylinder pressure information) is different even for the same elapsed time and deviates from the true correlation. However, as in the present embodiment, the correlation between the number of cycles and the integrated value is If the fuel property is detected from the relationship, the influence can be eliminated, and the structure is simplified and highly accurate compared to the structure that detects the fuel property from the correlation between the predetermined time and the integrated value. The fuel property can be detected.

Further, in the present embodiment, the cooling water temperature Tw is used as the temperature state 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.

[0042]

As described above, according to the fuel property detecting device for an internal combustion engine according to the invention described in claim 1, the in-cylinder pressure information for each predetermined operation cycle is detected and detected after the start start condition is satisfied. Since the calculated value of the in-cylinder pressure information is detected based on what level the calculated value of the in-cylinder pressure information is at when a predetermined time (or a predetermined operation cycle) has elapsed from the start of the start, it is relatively easy. With such a configuration, it becomes possible to detect the fuel property with high accuracy as early as possible after the start of starting.

Therefore, for example, the property of the fuel used is detected at an extremely early stage, as compared with the conventional device in which the property of the fuel used is detected by changing the operating condition after a predetermined operation condition is satisfied after the start. At the same time, it is possible to completely avoid a situation in which the drivability, the exhaust performance and the like are deteriorated due to the fuel property detection. 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 early so as to match the fuel used at that time. It is possible to provide an air-fuel ratio control device that can be improved. According to the second aspect of the present invention, the properties (heavy / light) of the fuel used can be detected quickly and accurately with a simple configuration. According to the inventions of claims 3 and 4, even if the state (temperature or density) of the intake air changes according to the change of the temperature state such as the outside air temperature or the engine temperature, and the cylinder pressure information changes, Alternatively, even if the ignition characteristics, the startability, and the like change according to the temperature state, it is possible to suppress a decrease in the detection accuracy of the fuel property due to these changes, so that the detection accuracy of the fuel property is always the desired accuracy. can do. Claim 5
According to the invention described in (1), since the fuel property is detected from the correlation between the number of operation cycles from the start of the start and the calculated value of the in-cylinder pressure information, the elapsed time and the calculated value of the in-cylinder pressure information are simply compared. Compared with the configuration that detects the fuel property from the correlation, it is possible to suppress the adverse effect on the detection accuracy due to the difference in cranking rotation speed during starting, etc., and detect the fuel property with high accuracy while simplifying the configuration. be able to. According to the invention as set forth in claim 6, the number of operating cycles is not counted up when the fuel is not injected and there is no possibility of combustion, so that the detection accuracy of the fuel property is reliably maintained at a high level. can do.

[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 an embodiment of the present invention.

FIG. 3 is a flowchart illustrating a fuel property detection control according to the above embodiment.

FIG. 4 is a diagram for explaining the difference between the number of operation cycles (or elapsed time) from the start of startup and Pis due to the difference in fuel property (at Tw = 25 ° C.).

FIG. 5 is a diagram for explaining the difference between the number of operation cycles (or elapsed time) from the start of start-up and Pis due to the difference in fuel property (at Tw = 10 ° C.).

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

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

[Explanation of symbols]

 1 Engine 6 Fuel Injection Valve 12 Control Unit 14 Crank Angle Sensor 15 Water Temperature Sensor 16 Cylinder Pressure Sensor 17 Key Switch

Claims (6)

[Claims] 1. An engine start start condition detecting means for detecting an engine start start condition, an elapsed time detecting means for detecting an elapsed time after the engine start start condition is detected, and an in-cylinder pressure detecting means for detecting an in-cylinder pressure of the engine. And, based on the in-cylinder pressure detected by the in-cylinder pressure detecting means, in-cylinder pressure cycle information detecting means for detecting in-cylinder pressure information for each predetermined operation cycle, and in-cylinder pressure information detected by the in-cylinder pressure cycle information detecting means. In-cylinder pressure information calculation means, the elapsed time after the engine start start condition is detected, and the calculated value of the in-cylinder pressure information calculated by the in-cylinder pressure information calculation means until the elapsed time after the engine start start condition is detected. A fuel property detecting device for an internal combustion engine, comprising: a fuel property detecting means for detecting a property of a used fuel based on the above. 2. The fuel property detection means, when the elapsed time after the engine start start condition is detected reaches a predetermined elapsed time,
The internal combustion engine according to claim 1, wherein the property of the fuel used is detected based on whether or not the calculated value of the in-cylinder pressure information calculated by the in-cylinder pressure information calculation means is equal to or greater than a predetermined value. Fuel property detector. 3. The fuel property detecting device for an internal combustion engine according to claim 2, wherein the predetermined elapsed time is variably set according to a temperature state. 4. The fuel property detection device for an internal combustion engine according to claim 2 or 3, wherein the predetermined value is variably set according to a temperature state. 5. The fuel property detecting device for an internal combustion engine according to claim 1, wherein the elapsed time is the number of operating cycles. 6. The fuel property detection device for an internal combustion engine according to claim 5, wherein the number of operation cycles is detected based on the number of injections of the fuel injection valve.