JP4325362B2 - Fuel property determination device for internal combustion engine - Google Patents

Description

  The present invention relates to a fuel property determination device for an internal combustion engine that determines the property of fuel injected and supplied to an internal combustion engine such as an in-vehicle internal combustion engine.

Conventionally, as this type of fuel property determination apparatus (determination method), there is an apparatus (method) described in Patent Document 1, for example. That is, in this apparatus (method), the ignition timing of the air-fuel mixture is forcibly corrected to the progressive advance side, and it is determined whether or not knocking due to this correction has occurred, and when the occurrence of knocking is determined When the advance amount of the ignition timing is large, the octane number (fuel property) is high, and when the advance amount is small, it is determined that the octane number is low.
JP-A-4-136482

  According to such an apparatus (method), based on an indirect factor such as the operating state of the internal combustion engine (fuel mixture ignition timing), the characteristics (octane number) of the fuel injected and supplied to the engine from time to time. ) Can certainly be determined. However, in general, the frequency of knocking that occurs in an internal combustion engine depends not only on the octane number (fuel properties) of the fuel, but also on other disturbances such as individual differences of the internal combustion engine, weather conditions, and secular changes such as deposit adhesion. Is done. In particular, if deposits such as fuel or oil or carbides or oxides of their additives adhere to the surface of the inner wall of the cylinder to form a heat insulation layer, the temperature of the combustion chamber will rise and knocking will occur. The frequency of occurrence increases. Therefore, it is difficult to obtain an accurate octane number of the fuel with the above-described apparatus (method) that uniquely determines the octane number of the fuel based on the ignition timing of the air-fuel mixture. As described above, in the conventional fuel property determination device, a decrease in accuracy in determining the fuel property is inevitable.

  The present invention has been made in view of such circumstances, and provides a fuel property determination device for an internal combustion engine that can determine the fuel property with higher accuracy even in an environment in which a disturbance acts on the internal combustion engine. For the purpose.

In the following, means for achieving the above object and its effects are described.
According to the first aspect of the present invention, as a fuel property determination device for an internal combustion engine, an intake passage fuel injection valve that injects and supplies fuel into the intake passage of the internal combustion engine, and a cylinder that directly injects and supplies fuel to the combustion chamber of the engine There is a correlation between the fuel characteristics of the internal fuel injection valve and when the fuel is mainly supplied by the fuel injection by the in-cylinder fuel injection valve and when the fuel is mainly supplied by the intake passage fuel injection valve. A fuel property determination device for an internal combustion engine, comprising: a determination unit that compares a parameter to calculate a relative value and determines a property of the fuel based on the calculated relative value, Parameters that correlate with the properties of the fuel when fuel is supplied mainly by fuel injection by the injection valve, and fuel that is mainly supplied by fuel injection by the intake passage fuel injection valve Preliminary determination means for determining the fuel property based on any of the parameters correlated with the fuel property at the time of performing, and deposit adhesion to the intake passage fuel injection valve and the in-cylinder fuel injection valve An estimation means for estimating each amount, and whether or not deposits are biased on either one of the intake passage fuel injection valve and the in-cylinder fuel injection valve based on the estimated deposit adhesion amount A bias determining means, and when the bias determining means determines that deposit is biased to one of the intake passage fuel injection valve and the in-cylinder fuel injection valve, the preliminary determining means The fuel property is determined, and it is determined that no deposit is adhered to either the intake passage fuel injection valve or the in-cylinder fuel injection valve. When it is to its gist that determines fuel property by the determination means.

Many of the disturbances described above act in a similar manner on both the intake passage fuel injection valve and the in-cylinder fuel injection valve. For example, intake air temperature, intake air humidity, individual differences of elements other than the above fuel injection valves, aging, and the like. In this regard, according to the above configuration, in order to determine the properties of the fuel based on relative values obtained by comparing parameters correlated with the properties of the fuel when the fuel is mainly supplied by the fuel injection valves. Disturbances that act similarly on both the intake passage fuel injection valve and the in-cylinder fuel injection valve are canceled out, and as a result, a decrease in accuracy of fuel property determination due to the above-described disturbance is suppressed.
Deposits such as fuel and oil used in an internal combustion engine or carbides or oxides of their additives may adhere to the intake passage fuel injection valve and the in-cylinder fuel injection valve. Such a tendency is particularly strong in an in-cylinder fuel injection valve disposed in a combustion chamber of an internal combustion engine. For this reason, if the determination of the fuel property by the determination means is performed when the deposit adheres to either the intake passage fuel injection valve or the in-cylinder fuel injection valve, it is caused by the deposit adhesion. There is concern about a decrease in accuracy. In this regard, according to the above configuration, when it is determined by the bias determination means that the deposit is attached to one of the two fuel injection valves, the preliminary determination means determines the fuel property, When it is determined that no deposit is attached to either one of the two fuel injection valves, the determination of the fuel property by the determination means improves the reliability in determining the fuel property. It becomes like this.

  According to a second aspect of the present invention, in the fuel property determination apparatus for an internal combustion engine according to the first aspect, the relative value calculated by the determination means is any of a parameter difference and a ratio correlated with the fuel property. The gist of this is that.

  As the relative value, any one of a parameter difference and a ratio correlated with the fuel property can be used. And any of these values allows the component due to the disturbance to be canceled out favorably.

The invention described in claim 3 is the fuel property determination device for an internal combustion engine according to claim 1 or 2, before Symbol estimating means, the deposit adhesion amount for each fuel injection valve from the intake passage fuel injector The gist of the estimation is based on the fuel injection amount and the fuel injection amount from the in-cylinder fuel injection valve.

When deposit biased to one of the air intake passage fuel injection valve and the in-cylinder fuel injection valve is attached, the amount of fuel injected from the fuel injection valve is reduced. Therefore, it is effective to estimate the deposit adhesion amount for each fuel injection valve based on the fuel injection amount from the intake passage fuel injection valve and the fuel injection amount from the in-cylinder fuel injection valve, Also, the estimation accuracy is ensured.

According to a fourth aspect of the present invention, in the fuel property determination apparatus for an internal combustion engine according to any one of the first to third aspects, the property of the fuel is an octane number, and the parameter has a correlation with the property of the fuel. The gist of this is either the ignition timing or the knocking strength.

  In general, the lower the octane number of the fuel, the greater the strength of knocking that occurs in the internal combustion engine. Therefore, the knocking strength is a parameter correlated with the octane number of the fuel. Also, when knocking is detected, when the KCS (Knock Control System) is operated to avoid knocking by delaying the ignition timing of the mixture from the base ignition timing, the ignition timing corresponds to the frequency of occurrence of knocking. To be. Incidentally, the base ignition timing here corresponds to the ignition timing when knocking does not occur. In general, the lower the octane number of the fuel, the higher the frequency of knocking. Therefore, the ignition timing is a parameter correlated with the octane number of the fuel. For this reason, when the fuel property is the octane number of the fuel, it is particularly effective to use these parameters as parameters correlated with the fuel property.

(First embodiment)
A first embodiment of a fuel property determination apparatus for an internal combustion engine according to the present invention will be described below. The fuel property determination device for an internal combustion engine according to this embodiment is also fuel that is injected and supplied to the engine from time to time based on the operating state of the internal combustion engine, similarly to the conventional fuel property determination device (determination method) described above. The property (octane number) is determined. However, the fuel property determination device for an internal combustion engine according to this embodiment has the configuration described below, thereby suppressing a decrease in accuracy in determining the fuel property due to disturbance as described above. .

  FIG. 1 schematically shows a schematic configuration of a fuel property determination apparatus for an internal combustion engine. Although the internal combustion engine 10 is a V-type six-cylinder gasoline engine having six cylinders, only one cylinder is shown as a representative in FIG. 1 for convenience of explanation.

  As shown in FIG. 1, this apparatus is mainly configured of an internal combustion engine 10 that is a four-cycle reciprocating engine. The internal combustion engine 10 includes a cylinder 1 having a cylinder block 1a and a cylinder head 1b connected to the upper portion of the cylinder block 1a, and a piston 2 that reciprocates in the cylinder 1. Has been. In the cylinder 1, a combustion chamber 5 for combusting the air-fuel mixture is defined by the inner walls of the cylinder block 1 a and the cylinder head 1 b and the top surface of the piston 2.

  The cylinder head 1b is provided with an ignition plug 6 for igniting the air-fuel mixture in a manner protruding into the combustion chamber 5, and an in-cylinder fuel injection valve I2 as fuel supply means for injecting and supplying fuel to the combustion chamber 5. It is installed. Further, the cylinder head 1b has an intake port 7 for taking air, fuel or the like into the combustion chamber 5, and an exhaust port 8 for discharging exhaust gas generated by combustion of the air-fuel mixture from the combustion chamber 5 to the outside. Are provided with an intake valve 7a and an exhaust valve 8a for opening and closing these ports, respectively. Here, the intake port 7 is provided with an intake passage fuel injection valve I1 as fuel supply means for injecting and supplying fuel to the intake port 7. Although not shown, a throttle valve that opens and closes to adjust the intake air amount is provided upstream of the intake port 7. Further, an air flow meter for detecting the intake air amount and an intake air temperature sensor for detecting the temperature of the intake air are disposed further upstream of the throttle valve.

  Further, the in-cylinder fuel injection valve I2 and the intake passage fuel injection valve I1 include a fuel tank T in which used fuel is stored, a low-pressure fuel pump P1 that pumps fuel in the fuel tank T to each fuel injection valve, and The high-pressure fuel pump P2 is connected by pipes such as delivery pipes D1 and D2 that supply fuel to each cylinder. Each of these elements constitutes a fuel supply device. Then, the fuel in the fuel tank T is supplied to each fuel injection valve by this fuel supply device. Specifically, the fuel pumped up from the fuel tank T by the low-pressure fuel pump P1 is supplied to the intake passage fuel injection valve I1 provided in each cylinder through the delivery pipe D2 with a pressure of, for example, about 0.3 MPa. The fuel further pressurized by the high-pressure fuel pump P2 is supplied to the in-cylinder fuel injection valve I2 included in each cylinder through the delivery pipe D1 with a pressure of, for example, 8 MPa to 13 MPa.

  On the other hand, the cylinder block 1a and the cylinder head 1b are provided with a water jacket 1c serving as a cooling water passage for cooling both of them (for convenience, only the water jacket on the cylinder block 1a side is shown). The cylinder block 1a is provided with a water temperature sensor 1d for detecting the temperature of the cooling water flowing through the water jacket 1c, and a knock sensor 1e for detecting knocking by detecting high-frequency vibrations.

  A crankshaft 3 is connected to the lower end of the piston 2 via a connecting rod (connecting rod) 4, and the crankshaft 3 rotates following the reciprocating motion of the piston 2. A crank angle sensor 3 a that detects the rotation angle of the crankshaft 3 is disposed in the vicinity of the crankshaft 3.

  The fuel property determination apparatus for an internal combustion engine having the above-described configuration is configured to take in output signals from the crank angle sensor 3a, the water temperature sensor 1d, the knock sensor 1e, and various sensors such as an air flow meter to the electronic control unit 100. . The electronic control unit 100 controls the driving of the ignition plug 6, the intake passage fuel injection valve I1, the in-cylinder fuel injection valve I2, the low pressure fuel pump P1, the high pressure fuel pump P2, and the like based on signals from these sensors. To do.

  The electronic control device 100 is mainly configured to include a CPU (Central Processing Unit) 101, a ROM (Read Only Memory) 102, a RAM (Random Access Memory) 103, and a backup RAM 104. These elements are electrically connected to each other by a bidirectional bus (not shown) or the like. Here, the CPU 101 performs arithmetic processing based on a control program, a data map, etc. stored in the ROM 102. Specifically, the ROM 102 includes various control programs for performing valve timing control, air-fuel ratio control, ignition timing control, fuel injection timing control, maps for calculating target values corresponding to various conditions, and the like. Is stored. The RAM 103 is used to temporarily store data and calculation results during the calculation by the CPU 101 or data input from the various sensors. The backup RAM 104 is used to hold various data stored in the RAM 103 when power supply is stopped.

  Hereinafter, the principle of the octane number determination by the fuel property determination device for the internal combustion engine according to this embodiment will be described with reference to FIG. FIG. 2 shows a case where fuel injection (port injection) is performed using only the intake passage fuel injection valve I1 and a case where fuel injection (in-cylinder injection) is performed using only the in-cylinder fuel injection valve I2. 4 is a graph showing a comparison between the timing of ignition of the air-fuel mixture by the spark plug 6 (ignition timing) and the octane number of the fuel. In FIG. 2, the characteristic line indicated by “L1” indicates the port injection characteristic, and the characteristic line indicated by “L2” indicates the in-cylinder injection characteristic.

  The device according to this embodiment is equipped with a KCS (knock control system) that, when knocking is detected by the knock sensor 1e, prevents the knocking by delaying the ignition timing of the air-fuel mixture from the base ignition timing. ing. Incidentally, the base ignition timing here corresponds to the ignition timing when knocking does not occur. When the system is in operation, the ignition timing corresponds to the frequency of knocking. Here, in order to distinguish from the base ignition timing, such an ignition timing is referred to as a knock ignition timing. In general, the lower the octane number of the fuel, the higher the frequency of knocking. Therefore, as shown in FIG. 2, the knock ignition timing is a parameter correlated with the octane number of the fuel.

  Here, it is also possible to determine the octane number of the fuel based on the characteristic line L1 or the characteristic line L2 in FIG. However, as described above, the occurrence frequency of the knocking depends not only on the octane number of the fuel, but also on other disturbances such as individual differences of the engine, weather conditions, and secular changes such as deposit adhesion. In particular, when deposits such as fuel, oil, or carbides or oxides of their additives adhere to the inner wall surface of the cylinder 1 to form a heat insulation layer, the temperature of the combustion chamber rises. Knocking occurs more frequently. For this reason, it has been described above that it is difficult to obtain an accurate octane number of fuel by such a method.

  In this respect, in the fuel property determination device of this embodiment, the difference between the knock ignition timing when performing port injection (characteristic line L1) and the knock ignition timing when performing in-cylinder injection (characteristic line L2). By determining the octane number of the fuel based on the above, the above-described decrease in determination accuracy is suppressed. Specifically, many of the disturbances act similarly on both the intake passage fuel injection valve I1 and the in-cylinder fuel injection valve I2. For example, intake air temperature, intake air humidity, individual differences of elements other than the above fuel injection valves, aging, and the like. Therefore, the fuel property determination device according to this embodiment compares the knock ignition timing when performing port injection (characteristic line L1) with the knock ignition timing when performing in-cylinder injection (characteristic line L2). The difference between these knock ignition timings is calculated, and the octane number of the fuel is determined based on the calculated difference in knock ignition timing. As described above, if the octane number determination is performed based on the difference between the knock ignition timing at the time of port injection and the knock ignition timing at the time of in-cylinder injection, the intake passage fuel injection valve I1 and the in-cylinder Disturbances acting on both of the fuel injection valves I2 in the same way are canceled out, and as a result, a decrease in the accuracy of fuel property determination due to the aforementioned disturbances is suppressed.

  Next, with reference to FIG. 3, the determination procedure when the octane number determination is performed by the fuel property determination device for the internal combustion engine according to this embodiment will be described. The process shown in FIG. 3 is repeatedly executed, for example, every predetermined crank angle or every predetermined time.

In the series of processes shown in FIG. 3, first, it is determined whether or not the octane number determination operation condition is satisfied. In particular,
(A) It is determined whether or not the engine is warming up. More specifically, it is determined whether or not the cooling water temperature detected from the water temperature sensor 1d has reached a predetermined value or more.
(B) It is determined whether or not the engine speed is stable. More specifically, it is determined whether or not the rate of change of the engine rotation speed detected by the crank angle sensor 3a or the like is equal to or less than a predetermined value.
(C) Determine whether the load is stable. More specifically, it is determined whether or not the rate of change of the load detected by an air flow meter or the like is a predetermined value or less.
(D) It is determined whether or not the KCS is operating. More specifically, it is determined whether or not the ignition timing is on the retard side with respect to the base ignition timing.
Etc. are performed (step S100).

  If it is determined in step S100 that the octane number determination operation condition is satisfied, then the knock ignition timing is acquired. More specifically, this knock ignition timing is acquired (calculated) based on the occurrence frequency of knocking detected by knock sensor 1e (step S110).

  Next, the injection method is switched from port injection to in-cylinder injection, or from in-cylinder injection to port injection (step S120). Then, as in step S110, the knock ignition timing is acquired (calculated) (step S130).

  Next, the knock ignition timing when performing port injection thus obtained is compared with the knock ignition timing when performing in-cylinder injection, and the difference between these knock ignition timings is calculated (step S140). Then, the octane number of the fuel is calculated (determined) based on the calculated difference in knock ignition timing (step S150). In this embodiment, the part that calculates (determines) the octane number of the fuel based on the calculated difference in knock ignition timing corresponds to the determination means.

  Then, based on the calculated (determined) octane number of the fuel, the injection method is switched to port injection or in-cylinder injection (step S160). Note that the various arithmetic processes described above are performed by the electronic control device 100.

As described above, according to the fuel property determination device for an internal combustion engine according to this embodiment, the following excellent effects can be obtained.
(1) As a fuel property determination device for an internal combustion engine, an intake passage fuel injection valve I1 that injects fuel into the intake passage of the internal combustion engine, and an in-cylinder fuel injection valve I2 that directly injects fuel into the combustion chamber of the engine And determination means for determining (calculating) the octane number of the fuel. Then, the determination means compares the knock ignition timing when performing the port injection with the knock ignition timing when performing the in-cylinder injection, and calculates the difference between these knock ignition timings. The configuration is such that the octane number of the fuel is determined (calculated) based on the difference in knock ignition timing. As a result, disturbances that act similarly on both the intake passage fuel injection valve I1 and the in-cylinder fuel injection valve I2 are canceled out, and as a result, a decrease in the accuracy of fuel property determination due to the above-described disturbance is suppressed.

(Second Embodiment)
Next, a second embodiment of the fuel property determination device for an internal combustion engine according to the present invention will be described. Similarly to the first embodiment, the fuel property determination device for an internal combustion engine according to this embodiment suppresses a decrease in accuracy in determining the fuel property (octane number) due to the disturbance as described above. Yes. However, the fuel property determination device for an internal combustion engine according to this embodiment further includes preliminary determination means described below, and the preliminary determination means is provided according to disturbances acting on the intake passage fuel injection valve I1 and the in-cylinder fuel injection valve I2, respectively. By properly using the determination means and the determination means, the reliability in determining the fuel property is also improved.

  Now, this fuel property determination apparatus is basically also an apparatus having the configuration shown in FIG. 1 as in the first embodiment. However, this apparatus is further provided with an air-fuel ratio sensor 8b composed of, for example, an O2 sensor as indicated by a broken line in FIG. More specifically, the air-fuel ratio sensor 8b is disposed downstream of the exhaust port 8, and the air-fuel ratio (the mass of air / the mass of fuel) is rich with respect to the stoichiometric air-fuel ratio (≈14.7). ) Or lean (thin) state.

  By the way, in the fuel property determination apparatus of the first embodiment, the above-described disturbance may be applied to one of the intake passage fuel injection valve I1 and the in-cylinder fuel injection valve I2.

  Therefore, in the fuel property determination device of this embodiment, in consideration of such circumstances, the octane number of the fuel is based on either the knock ignition timing when performing port injection or the knock ignition timing when performing in-cylinder injection. It is further provided with preliminary determination means for performing the determination. Then, it is determined whether a disturbance is acting on one of the intake passage fuel injection valve I1 and the in-cylinder fuel injection valve I2, and based on the determination result, the preliminary determination means, the determination means, Are used properly.

  Hereinafter, with reference to FIG. 4 as well, the determination procedure when the octane number determination is performed by the fuel property determination device for the internal combustion engine according to this embodiment will be described in detail. Here, it is determined whether deposits are biased toward either the intake passage fuel injection valve I1 or the in-cylinder fuel injection valve I2, and the preliminary determination means and the determination means are determined based on the determination result. And are used properly. The process shown in FIG. 4 is also repeatedly executed, for example, every predetermined crank angle or every predetermined time.

In the series of processes shown in FIG. 4, first, the basic injection amount is calculated based on the intake air amount detected by the air flow meter (step S200).
Next, based on the air-fuel ratio signal detected by the air-fuel ratio sensor 8b, an air-fuel ratio feedback coefficient FAF for correcting the air-fuel ratio that changes with time is calculated (step S210). Based on the steady tendency of the calculated air-fuel ratio feedback coefficient FAF, the base value is learned to improve the air-fuel ratio control accuracy during the internal combustion engine transient operation. This learning is performed for each operation region of the internal combustion engine, for example (step S220).

  Next, based on the calculated air-fuel ratio feedback coefficient FAF and the learned base value, the fuel injection amount from the intake passage fuel injection valve I1 and the fuel injection amount from the in-cylinder fuel injection valve I2 are respectively estimated. . Incidentally, this estimation is performed based on the fact that when deposits are deposited on these fuel injection valves, the amount of fuel injected from the fuel injection valves decreases (step S230). Next, based on the estimated fuel injection amount from each fuel injection valve, the deposit adhesion amount adhering to each fuel injection valve is estimated (calculated), respectively (step S240). In addition, the site | part which estimates this deposit adhesion amount corresponds to an estimation means. Then, it is determined from the estimated deposit adhesion amount to each fuel injection valve whether or not deposit is attached to either the intake passage fuel injection valve I1 or the in-cylinder fuel injection valve I2. Specifically, it is determined whether or not the difference between the deposit adhesion amount of the intake passage fuel injection valve I1 and the deposit adhesion amount of the in-cylinder fuel injection valve I2 is a predetermined value or more (step S250). Note that the portion where the deposit adhesion determination is made corresponds to the bias determination means.

  Here, if it is determined that the deposit is biased toward one of the intake passage fuel injection valve I1 and the in-cylinder fuel injection valve I2, the preliminary determination means determines (calculates) the octane number of the fuel. Will be done. Specifically, the characteristic line L1 indicating the relationship of “knock ignition timing−fuel octane number” when performing the port injection shown in FIG. 2 and “knock ignition timing−fuel octane number” when performing in-cylinder injection are shown. The octane number of the fuel is determined based on one of the characteristic lines L2 indicating the relationship (step S251). In addition, the site | part which performs this determination corresponds to a preliminary determination means. On the other hand, if it is determined that no deposit is biased toward either one of the intake passage fuel injection valve I1 or the in-cylinder fuel injection valve I2, the determination means performs the determination procedure shown in FIG. Determination (calculation) of the octane number of the fuel is performed (step S252). The various arithmetic processes described above are also performed by the electronic control device 100.

  As described above, according to the fuel property determination device for an internal combustion engine according to this embodiment, the fuel property can be obtained even when deposit is biased to one of the intake passage fuel injection valve and the in-cylinder fuel injection valve. Reliability is ensured in determining.

  As described above, according to the fuel property determination device for an internal combustion engine according to the second embodiment, an effect similar to or equivalent to the effect (1) of the previous first embodiment is obtained. In addition, the following effects can be newly obtained.

  (2) Preliminary determination means for determining the octane number of the fuel based on either a knock ignition timing when supplying fuel by port injection or a knock ignition timing when supplying fuel by in-cylinder injection is provided. Further, estimation means for estimating the deposit adhesion amount respectively attached to the intake passage fuel injection valve I1 and the in-cylinder fuel injection valve I2, and the intake passage fuel injection valve I1 and the intake passage fuel injection valve I1 based on the deposit adhesion amount estimated by the estimation means There is further provided a bias determining means for determining whether deposits are biased toward any one of the in-cylinder fuel injection valves I2. Then, according to the determination result of the bias determination means, the preliminary determination means and the determination means described above are used properly. Accordingly, even when deposits are biased toward one of the intake passage fuel injection valve I1 and the in-cylinder fuel injection valve I2, more reliable determination of the fuel property is realized through the preliminary determination means. It becomes like this.

(Other embodiments)
In addition, each said embodiment can also be implemented with the following aspects.
In the second embodiment, the deposit adhesion amount for each fuel injection valve is estimated based on the fuel injection amount from each fuel injection valve, but the deposit adhesion amount estimation method is arbitrary. Further, the disturbance acting on each fuel injection valve is not limited to deposit adhesion. For example, the performance deterioration degree of each fuel injection valve due to disturbance such as physical impact or chemical action may be estimated.

  In each of the above embodiments, the knock ignition timing when in-cylinder injection is performed is compared with the knock ignition timing when port injection is performed, and the difference between these knock ignition timings is calculated. However, this calculated value is not limited to the difference in knock ignition timing, and may be, for example, the ratio of knock ignition timing. In short, a relative value between the knock ignition timing when performing in-cylinder injection and the knock ignition timing when performing port injection is sufficient.

  In each of the above embodiments, when fuel injection (in-cylinder injection) is performed using only the in-cylinder fuel injection valve I2, and when fuel injection (port injection) is performed using only the intake passage fuel injection valve I1. A comparison was made. However, this comparison is not limited to the case where fuel injection is performed using only each fuel injection valve. In short, it is sufficient to make a comparison between when the fuel is mainly supplied by the fuel injection by the cylinder fuel injection valve I2 and when the fuel is mainly supplied by the fuel injection by the intake passage fuel injection valve.

  In each of the above embodiments, the octane number of the fuel is calculated based on the difference in the knock ignition timing of each fuel injection valve, but whether the fuel is a high-octane fuel based on the difference in the knock ignition timing is determined. It is good also as a structure which determines only whether it is. Further, according to such a configuration, the configuration of the fuel property determination device itself can be simplified.

  In each of the above embodiments, the property of the fuel to be determined is the octane number, and the ignition timing (knock ignition timing) is used as a parameter correlated with the octane number of the fuel. However, these parameters are not limited to the ignition timing, and may be parameters that are correlated with the octane number of the fuel. For example, knocking strength, air-fuel ratio, PM emission amount, or the like can also be used as such parameters. Further, the property of the fuel to be determined is not limited to the octane number, and may be a distillation characteristic or an aromatic component amount.

  In each of the above embodiments, the determination process shown in FIG. 3 or FIG. 4 is repeated every predetermined crank angle or every predetermined time, but this determination process is executed only once every engine start. Also good.

  In each of the above embodiments, it is assumed that the determination unit and the preliminary determination unit are stored in the ROM 102 as a program, for example. However, the determination unit and the preliminary determination unit can be realized by a dedicated circuit using hardware. is there.

The block diagram which shows typically the schematic structure about 1st Embodiment of the fuel-characteristics determination apparatus of the internal combustion engine concerning this invention. The graph which shows the principle of the octane number determination in the same embodiment. The flowchart which shows the process sequence about the fuel property determination process of the embodiment. The flowchart which shows the process sequence of the fuel property determination process about 2nd Embodiment of the fuel property determination apparatus of the internal combustion engine concerning this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Cylinder, 1d ... Water temperature sensor, 1e ... Knock sensor, 2 ... Piston, 3 ... Crankshaft, 3a ... Crank angle sensor, 4 ... Connecting rod, 5 ... Combustion chamber, 6 ... Spark plug, 7 ... Intake port, 7a DESCRIPTION OF SYMBOLS ... Intake valve, 8 ... Exhaust port, 8a ... Exhaust valve, 8b ... Air-fuel ratio sensor, 10 ... Internal combustion engine, 100 ... Electronic control unit, 101 ... CPU, 102 ... ROM, 103 ... RAM, I1 ... Intake passage fuel injection valve , I2 ... In-cylinder fuel injection valve, P1 ... Low pressure fuel pump, P2 ... High pressure fuel pump, T ... Fuel tank.

Claims (4)

An intake passage fuel injection valve for injecting fuel into the intake passage of the internal combustion engine;
An in-cylinder fuel injection valve that directly injects fuel into the combustion chamber of the engine;
Parameters that correlate with the properties of the fuel when the fuel is mainly supplied by the fuel injection by the in-cylinder fuel injection valve and when the fuel is mainly supplied by the fuel injection valve by the intake passage fuel A fuel property determination device for an internal combustion engine, comprising: a determination unit that calculates a relative value and determines the property of the fuel based on the calculated relative value ;
Parameters that correlate with the properties of the fuel when fuel is supplied mainly by fuel injection by the in-cylinder fuel injection valve and fuel that is supplied when fuel is mainly supplied by fuel injection by the intake passage fuel injection valve. Preliminary determination means for determining the fuel property based on one of the parameters correlated with the property, and estimation for estimating the deposit amount attached to the intake passage fuel injection valve and the in-cylinder fuel injection valve, respectively And bias determination means for determining whether deposits are biased toward one of the intake passage fuel injection valve and the in-cylinder fuel injection valve based on the estimated deposit amount. Prepared,
When it is determined by the bias determination means that deposits are biased on either the intake passage fuel injection valve or the in-cylinder fuel injection valve, the preliminary determination means determines the fuel property, and the intake air When it is determined that no deposit is biased toward either one of the passage fuel injection valve and the in-cylinder fuel injection valve, the fuel property is determined by the determination means.
A fuel property determination apparatus for an internal combustion engine. The fuel property determination device for an internal combustion engine according to claim 1, wherein the relative value calculated by the determination means is any one of a difference and a ratio of parameters correlated with the property of the fuel. The fuel property determination apparatus for an internal combustion engine according to claim 1 or 2,
The internal combustion engine characterized in that the estimation means estimates a deposit adhesion amount to each fuel injection valve based on a fuel injection amount from the intake passage fuel injection valve and a fuel injection amount from the in-cylinder fuel injection valve. Fuel property judgment device. The property of the fuel is an octane number, and the parameter correlated with the property of the fuel is either ignition timing or knocking strength.
The fuel property determination apparatus for an internal combustion engine according to any one of claims 1 to 3 .

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