JP5187289B2 - Control device for internal combustion engine - Google Patents

Description

  The present invention relates to a control device for an internal combustion engine that can be operated even when using a mixed fuel obtained by mixing a plurality of types of fuels having different properties.

  Conventionally, not only a single type of fuel, but also a mixture of multiple types of fuel (for example, a mixture of light oil and gasoline, and a mixture of light oil, gasoline, and ethanol) is used. A "multi-fuel compatible internal combustion engine" that can be operated is known (see, for example, Patent Document 1). The fuel properties (for example, volatility and ignitability) of such a mixed fuel vary depending on the type and ratio of the fuel included in the mixed fuel.

  When such fuel is supplied to the fuel tank, there are two types: “fuel to be supplied (fuel supply fuel)” and “fuel stored in the fuel tank before being supplied (fuel before supply)”. If they are different, the fuel property of “the fuel stored in the fuel tank after being refueled (fuel after refueling)” is different from the fuel property of the fuel before refueling. For example, if the fuel before refueling is a fuel consisting only of light oil and the fuel supplied is a fuel consisting only of gasoline, the fuel after refueling is a mixed fuel of light oil and gasoline. Some cetane numbers change before and after refueling. Therefore, when the fuel property of the fuel after refueling is changed from the fuel property of the fuel before refueling, the fuel property of the fuel after refueling is changed in order to execute fuel injection control and air amount control suitable for the fuel property of the fuel after refueling. It is necessary to obtain a new one.

  On the other hand, immediately after refueling, the fuel before refueling and the refueling fuel are not sufficiently mixed in the fuel tank, for example, there is a fuel with a relatively large proportion of the refueling fuel in the upper part of the fuel tank, There may be a fuel having a relatively large proportion of fuel before refueling in the lower portion of the fuel tank. That is, the fuel after refueling immediately after refueling is not uniformly mixed with the fuel before refueling. For this reason, even if the fuel property of the fuel after refueling is acquired immediately after refueling, the acquired fuel property is the same as the fuel property of the fuel (supplied fuel) actually supplied to the engine via the fuel injection valve or the like. There may be a gap.

  In order to deal with such a problem, one of the prior arts acquires the alcohol concentration (value representing fuel properties) of the fuel before refueling and the alcohol concentration of the fuel after refueling, and these alcohol concentrations exceed a predetermined value. In the case of a difference, the electric fuel pump provided in the fuel tank is operated for a “certain time” before the engine is started. Further, in this conventional technique, fuel injection control is performed based on the uniform alcohol concentration of the fuel after refueling. According to this, since the fuel after refueling is made uniform by being agitated before starting the engine, engine control according to the fuel properties of the fuel actually supplied to the engine can be performed (Patent Document). 2).

  However, in the above prior art, since the operation time of the electric fuel pump is a fixed time, if the fixed time is too long, the fuel in the fuel tank is agitated excessively and the battery power (ie, electric energy) There is a problem of wasteful consumption. Note that a stirring device for stirring the fuel in the fuel tank may be provided separately from the electric fuel pump.

JP-A-5-1931 JP-A-6-26414

  The present invention has been made in view of the above-described problems, and one of its purposes is to agitate the mixed fuel existing in the fuel tank after refueling by an appropriate amount so as not to hinder the operation of the engine. Another object of the present invention is to provide a control device for an internal combustion engine that can reduce the amount of energy consumed for agitation of fuel.

Specifically, the fuel injection control device for an internal combustion engine according to the present invention is:
An internal combustion engine that can be operated by using a fuel stored in a “single” fuel tank, in which a plurality of types of fuels having different “fuel property values representing fuel properties” determined according to the type of fuel are mixed A control device of
The fuel property value before refueling, which is the fuel property value of “the fuel stored in the fuel tank at the time before refueling the fuel tank”, and the fuel of “fuel replenished to the fuel tank by the refueling” Of the two values, a fuel property value that is a fuel property value and a fuel property value that is after fueling that is a fuel property value of “fuel stored in the fuel tank at a time point after the fueling to the fuel tank” Information acquisition means for acquiring at least one of the remaining amount of fuel after refueling, which is the amount of "the fuel stored in the fuel tank at a time after the refueling of the fuel tank";
Stirring means for stirring the fuel stored in the fuel tank;
The target value of the amount of fuel agitated by the agitating means is determined by two values: the acquired pre-fuel supply fuel property value, the acquired fuel supply fuel property value, and the acquired post-fuel supply fuel property value. Calculation based on at least one of them and the acquired post-refueling fuel remaining amount, and "the engine starts operation with the fuel stored in the fuel tank" from "the time after the refueling" Agitation amount control means for operating the agitation means so that "the agitation means agitates the fuel stored in the fuel tank by the target value of the agitation amount" in the period until
Is provided.

  According to this, as described below, whether or not the “fuel property value before refueling” differs from the “fuel property value (or fuel property value after refueling)” or how much they differ. It is possible to change the “stirring amount target value” based on whether or not the fuel is present and the remaining fuel amount after refueling. As a result, it can be avoided that the stirring means consumes useless energy.

Here, the stirring amount control means includes:
When the acquired pre-fuel supply fuel property value is different from the acquired fuel supply fuel property value, or the acquired pre-fuel supply fuel property value and the acquired post-fuel supply fuel property value are If it is a different value, the target value of the agitation amount is calculated so that the target value of the agitation amount increases as the remaining amount of fuel after refueling increases.
When the acquired pre-fuel supply fuel property value and the acquired fuel supply fuel property value are the same value, or the acquired pre-fuel supply fuel property value and the acquired post-fuel supply fuel property value are When the values are the same, the target value of the stirring amount may be set to zero.

  When the type of fuel supplied (fuel property value) is different from the type of fuel before fuel supply (fuel property value), in order to make the distribution of fuel before fuel supply and fuel supplied in the fuel tank uniform, fuel after fuel supply It is necessary to stir more as the remaining fuel amount in the tank after refueling increases. In other words, the distribution of the pre-fuel supply fuel and the fuel supply fuel in the fuel tank can be made substantially uniform even if the amount of agitation is reduced as the remaining amount of fuel after refueling is smaller. Therefore, according to the said structure, it can avoid that the stirring means consumes useless energy.

  However, when the fuel property value before refueling and the fuel property value before refueling are equal, or when the fuel property value before refueling and the fuel property value after refueling are equal, the fuel that has been refueled is the same type of fuel as the fuel before refueling. So there is no need to stir. In such a case, according to the above configuration, the target value of the stirring amount is set to “0”. Therefore, it is possible to avoid that the stirring means consumes useless energy.

Alternatively, the stirring amount control means includes
The fuel property value change rate d is such that “the target value of the agitation amount increases as it approaches 50%” and “the target value of the agitation amount increases as the fuel remaining amount after refueling increases”. The target value of the stirring amount may be calculated.

The fuel property value change rate d is:
A fuel property value of a single type of fuel of a plurality of types of fuel assumed to be used in the engine and having the smallest fuel property value of the same fuel (minimum property value fuel) is defined as Nmin. ,
The fuel property value of “a fuel having the largest fuel property value of the same fuel (maximum property value fuel)”, which is another single kind of fuel among a plurality of types of fuel assumed to be used in the engine Is Nmax,
The fuel property value after refueling is Nm1,
When the fuel property value before refueling is Nm0,
The difference between the fuel property value Nm1 after refueling and the fuel property value Nm0 before refueling with respect to the difference in fuel property value between the minimum property value fuel and the maximum property value fuel (Nmax−Nmin = | Nmax−Nmin |) Is a ratio of | Nm1-Nm0 |.

  This fuel property value change rate d limits the type of fuel used in the engine (the fuel that is expected to be used), and indicates that the fuel property value in the fuel tank does not change at all before and after refueling. 0% ", and the change rate of the fuel property value before and after the actual refueling when the fuel property value of the fuel in the combustion tank changes the most before and after the refueling is defined as" 100% " is there.

  For example, when it is assumed that the internal combustion engine is operated with “two kinds of fuels of light oil and gasoline”, and the fuel property value is “a cetane number that is an index value indicating the ignitability of fuel” as described later. In this case, the maximum property value fuel is light oil and the minimum property value fuel is gasoline. Therefore, if the fuel property value (cetane number) of light oil is Nmd and the fuel property value (cetane number) of gasoline is Nmg, the difference in the fuel property value between the maximum property value fuel and the minimum property value fuel is large. The length is Nmax−Nmin = Nmd−Nmg.

  Now, it is assumed that gasoline is supplied when only light oil is present in the fuel tank before refueling and the remaining fuel amount (remaining fuel amount before refueling) is V0. At this time, the fuel property value Nm1 after refueling approaches the fuel property value Nmg of gasoline as the amount of gasoline to be fueled increases. Therefore, the fuel property value change rate d increases from 0% to 100% as the amount of gasoline to be supplied increases from “0”.

  And, if the amount of gasoline to be refueled is V0, the fuel property value Nm1 after refueling is (Nmd + Nmg) / 2 from the calculation of (Nmd · V0 + Nmg · V0) / (V0 + V0). The rate d is 50%. That is, when the fuel property value change rate d is 50%, among the fuels assumed to be used, the “fuel with the largest fuel property value and the fuel with the smallest fuel property value” are 1: 1 and the fuel tank Will exist within. In this case, if the fuel in the fuel tank is not agitated, “change in fuel property value of fuel used for engine” or “fuel property value after refueling used for engine control and fuel actually used for engine” The difference between the fuel property value and the fuel property value is the largest.

  On the other hand, for example, when only light oil is present in the fuel tank before refueling, and the light oil is refueled, the fuel property value change rate d becomes 0%. That is, as in the case where the amount of fuel supplied is extremely small, even if fuel having the same fuel property value as the fuel present in the fuel tank is supplied, the fuel property value change rate d becomes 0%, There is no need to agitate the fuel in the fuel tank.

  On the other hand, for example, it is assumed that a slight amount of light oil remains in the fuel tank before refueling. In this case, the fuel property value Nm0 before refueling is the fuel property value Nmd of light oil, and is equal to the maximum fuel property value Nmax. At this time, if a large amount of gasoline is supplied, the fuel property value Nm1 after refueling is substantially the fuel property value Nmg of gasoline, which is substantially equal to the minimum fuel property value Nmin. Therefore, the fuel property value change rate d is approximately 100%. However, as understood from this example, the fuel property value change rate d is approximately 100% when the fuel before refueling is substantially “0”. Therefore, also in this case, it is not necessary to agitate the fuel in the fuel tank.

  As understood from the above, it is desirable to maximize the amount of stirring when the fuel property value change rate d is 50%, and the amount of stirring becomes “0” as the fuel property value change rate d approaches 0 or 100%. It is desirable to be close to Therefore, as described above, the fuel property value change rate d is “the target value of the agitation amount increases as it approaches 50%” and “the higher the fuel remaining amount after refueling, the greater the agitation amount. The target value of the stirring amount is calculated so that the target value becomes large. As a result, the amount of stirring can be reduced within a range that does not hinder the operation of the engine, so that it is possible to avoid the use of unnecessary energy by the stirring means.

  The fuel property value may be configured to be represented by a cetane number.

  Each of a plurality of types of “fuels having different fuel properties” used in the engine has different cetane numbers. The cetane number is an index value indicating the ignitability of each fuel. For example, light oil and gasoline (possibly via, gasoline and alcohol fuel) are commonly used for engines. Of these fuels, diesel oil has the largest cetane number, gasoline has the largest cetane number, and alcohol has the smallest cetane number.

The information acquisition means includes
A pressure sensor that actually detects the pressure of the gas in the fuel tank;
A temperature sensor that actually detects the temperature of the gas in the fuel tank;
Including
Based on the gas pressure and the gas temperature detected before the refueling, the cetane number of the fuel stored in the fuel tank at the time prior to the refueling is calculated as the fuel property value before refueling. And the cetane number of the fuel stored in the fuel tank at the time after the refueling based on the pressure of the gas and the temperature of the gas detected at the time after the refueling. The fuel property value after refueling may be estimated.

  This configuration is particularly effective when two types of fuel are used. The vapor pressure characteristics of the various fuels stored in the fuel tank change according to the temperature. Therefore, when the temperature of the gas in the fuel tank is a certain temperature, the pressure of the gas changes according to the “mixing ratio of the two types of fuels being mixed”. Accordingly, a map showing the relationship between the gas pressure in the fuel tank, the temperature of the gas in the fuel tank, and the fuel mixing ratio is prepared in advance, and the vapor pressure (fuel) of the fuel mixture in the fuel tank is prepared. The mixing ratio can be obtained by obtaining the gas pressure in the tank) and the temperature of the gas in the fuel tank and applying these to the map, so the fuel of the fuel in the fuel tank can be obtained based on the mixing ratio. A property value can be estimated.

It is a schematic block diagram of the control apparatus of the internal combustion engine which concerns on each embodiment of this invention. 3 is a flowchart showing a “fuel agitation routine” executed by a CPU of the electric control device shown in FIG. 1. 3 is a flowchart showing a “target stirring time calculation routine” executed by the CPU of the electric control device shown in FIG. 1. 2 is a map showing a “relationship between gas temperature and gas pressure in a fuel tank” referred to by the CPU of the electric control device shown in FIG. 1. It is the graph which showed the relationship between the mixing rate of the gasoline in the fuel which consists of light oil and gasoline, and the pressure of the gas in a tank in case the temperature of the gas in a tank is predetermined temperature (t = t0). It is the flowchart which showed the "target stirring time calculation routine" which CPU of the electric control apparatus which concerns on 2nd Embodiment of this invention performs.

  Embodiments according to the present invention will be described below with reference to the drawings.

(First embodiment)
FIG. 1 is a diagram showing a configuration of a control device for an internal combustion engine according to an embodiment of the present invention. The internal combustion engine 10 is a four-cylinder in-cylinder injection internal combustion engine corresponding to three types of fuel, gasoline, light oil and alcohol, and is operated by diffusing and burning the supplied fuel. However, in the first embodiment, the engine 10 is assumed to use either light oil or gasoline as fuel. The engine 10 is mounted on the vehicle as a vehicle drive source (not shown). The engine 10 includes an intake system 20, an engine body 30, an exhaust system 40, a fuel supply system 50, and a control system 60.

  The intake system 20 includes an intake pipe 21 and an intake manifold 22 connected to the intake pipe 21. In the intake pipe 21, an air cleaner 23, a compressor 24 a of a supercharger 24, an intercooler 25, and a throttle valve 26 are arranged in order from the upstream side to the downstream side of the flow of air supplied to the engine 10.

  The engine body 30 opens and closes an intake port 31 connected to the intake manifold 22, an intake valve 32 that opens and closes the intake port 31, a piston 33, a crankshaft 34 coupled to the piston 33, an exhaust port 35, and an exhaust port 35. An exhaust valve 36 and a fuel injection valve 37 are provided. A combustion chamber 38 is formed in the engine body 30 by the cylinder head lower surface, the cylinder wall surface, the upper surface of the piston 33, and the like. The fuel injection valve 37 is opened in response to an instruction signal (fuel injection signal) from an electric control device 61 described later, and fuel is directly injected into the combustion chamber 38.

  When the intake valve 32 is opened, air is supplied to the combustion chamber 38 through the intake manifold 22 and the intake port 31. The fuel is injected from the fuel injection valve 37 and diffusely combusted when the air in the combustion chamber 38 is compressed by the compression operation of the piston 33. As a result, the piston 33 is pushed down and the crankshaft 34 rotates. Exhaust gas generated in the combustion chamber 38 is discharged from the combustion chamber 38 to the exhaust port 35 when the exhaust valve 36 is opened.

  The exhaust system 40 includes an exhaust manifold 41 connected to the exhaust port 35 and an exhaust pipe 42 connected to the exhaust manifold. In the exhaust pipe 42, a turbine 24b and an exhaust purification catalyst 43 of the supercharger 24 are disposed in order from the upstream side to the downstream side of the flow of exhaust gas discharged from the combustion chamber 38.

The turbine 24b is rotated by exhaust. Thereby, the compressor 24a is rotated and air is compressed. As a result, the supercharger 24 performs supercharging.
The exhaust purification catalyst 43 removes particulates and harmful substances contained in the exhaust that has passed through the turbine 24b.

  The fuel supply system 50 includes a fuel tank portion 51, an electric feed pump portion 52, a fuel supply pipe 53, a high pressure pump 54, and a common rail 55.

  The fuel tank unit 51 includes a fuel tank 51a that stores fuel that has been refueled, and a fuel refueling unit 51b into which fuel is poured during refueling. The fuel supply part 51b is tubular and is provided on the upper part of the fuel tank 51a. The tip portion of the fuel supply portion 51b constitutes a fuel supply port. The oil filler port is opened and closed by an oil filler cap 51c. When the fuel filler opening is closed by the fuel filler cap 51c, the fuel tank 51a forms a sealed space.

  The electric feed pump unit 52 is disposed near the bottom of the fuel tank 51a. The electric feed pump unit 52 includes an electric feed pump 52a, a fuel suction unit 52b, a fuel pressure feeding unit 52c, a return unit 52d, and a pressure sensing type check valve 52e.

  The electric feed pump 52a is driven when electric power is supplied from a battery (not shown) in response to a signal (driving signal) from an electric control device 61 described later. When the electric feed pump 52a is driven, the fuel contained in the fuel tank 51a is sucked from the fuel suction portion 52b, and the fuel is fed through the fuel pumping portion 52c to the “fuel supply pipe 53 connected to the fuel pumping portion 52c”. The pressure is fed (supplied). The pumping amount per unit time of the electric feed pump 52a is constant.

  The check valve 52e is disposed in the return portion 52d. The check valve 52e opens when the fuel pressure in the fuel pumping section 52c becomes equal to or higher than a predetermined pressure. For example, when the electric feed pump 52a is driven when the engine 10 is not operated (that is, when fuel is not required for the engine 10), the fuel pressure in the fuel pumping section 52c becomes equal to or higher than a predetermined pressure. As a result, “the fuel in the fuel tank 51a” sucked into the electric feed pump 52a from the fuel suction part 52b is returned to the fuel tank 51a again through the return part 52d. Therefore, the fuel in the fuel tank 51a is agitated by the electric feed pump 52a. As described above, since the pumping amount per unit time of the electric feed pump 52a is constant, if the electric feed pump 52a is driven for a predetermined time T when the engine 10 is stopped, The fuel is stirred by an amount proportional to the predetermined time T. The amount of fuel stirred in the fuel tank 51a is also referred to as “stirring amount”.

  As described above, one end of the fuel supply pipe 53 is connected to the fuel pumping section 52c. Further, the other end of the fuel supply pipe 53 is connected to the fuel injection valve 37. The fuel supply pipe 53 is provided with a high pressure pump 54 and a common rail 55 in order from the upstream to the downstream in the flow of fuel. During operation of the engine 10, the fuel pressure-fed to the fuel supply pipe 53 by the electric feed pump unit 52 is boosted (pressurized) by the high-pressure pump 54 and supplied to the common rail 55. Therefore, when the fuel injection valve 37 is opened, the high-pressure fuel in the common rail 55 is injected into the combustion chamber 38.

  The control system 60 includes an electric control device 61 mainly composed of a microcomputer including a CPU, a ROM, a RAM, a backup RAM, and the like, and performs various controls related to the operation of the internal combustion engine 10. The backup RAM can hold data stored in the backup RAM even when an ignition key switch (not shown) is off.

  The electric control device 61 includes an accelerator opening sensor 62, a crank angle sensor 63, an alcohol concentration sensor 64, a fuel remaining amount sensor 65, a tank internal pressure sensor 66, a tank internal temperature sensor 67, a fuel filler sensor 68, an air amount sensor 69, and the like. The acquired values detected by these sensors are input.

The accelerator opening sensor 62 detects the operation amount of the accelerator pedal AP operated by the driver.
The crank angle sensor 63 generates a pulse when the crankshaft 34 rotates by a predetermined angle. This pulse is converted into an engine speed NE by the electric control device 61.
The alcohol concentration sensor 64 is disposed in the fuel refueling part 51b and detects the concentration of alcohol (ethanol in this example) contained in the fuel that is refueled (supplemented) to the fuel tank 51a through the fuel refueling part 51b. It has become. The concentration of alcohol is detected based on, for example, the dielectric constant of the fuel to be supplied.
The remaining fuel sensor 65 detects the amount of fuel remaining in the fuel tank 51a by detecting the position of the float that moves together with the liquid level of the fuel tank 51a.
The tank internal pressure sensor 66 is disposed in the upper part of the fuel tank 51a. The tank internal pressure sensor detects the pressure of the gas (gas) existing above the fuel tank 51a when the fuel tank 51a is in a sealed state.
The tank internal temperature sensor 67 is disposed at the upper part of the fuel tank 51a. The tank internal pressure sensor detects the temperature of the gas (gas) existing above the fuel tank 51a when the fuel tank 51a is in a sealed state.
The fuel filler sensor 68 generates a signal according to whether or not the fuel filler of the fuel filler 51b is closed by the fuel cap 51c.
The air amount sensor 69 is disposed in the intake pipe 21. The air amount sensor 69 detects the amount (flow rate) of air flowing through the intake pipe 21.

  The electric control device 61 transmits an instruction signal to each part of the engine such as the throttle valve 26, the electric feed pump unit 52 (electric feed pump 52a), and the fuel injection valve 37 based on the acquired values received from various sensors. It is like that.

  Next, a fuel agitation routine executed by the control apparatus for an internal combustion engine according to the first embodiment of the present invention will be described with reference to FIG. The CPU of the electric control device 61 executes the fuel agitation routine every time a predetermined time elapses regardless of whether an ignition key switch (not shown) is off or on. If the CPU is configured to perform this fuel agitation routine when the ignition key switch is on, the fuel agitation routine allows the electric feed pump 52a to operate even when there is an operation to start the engine 10. The starter (engine starter) (not shown) is not driven until the operation is stopped (see step S260 described later).

  Now, description will be made on the assumption that the operation of the engine 10 is stopped, the fuel tank 51a is refueled, and then the refueling is finished. In this case, the CPU starts the process from step S200 in FIG. 2 at a predetermined timing, proceeds to step S210, and determines whether or not the current time is “immediately after refueling is completed”.

  More specifically, when the ignition key switch is changed from on to off (that is, when the engine 10 is stopped), the CPU detects the remaining fuel amount L0 (engine) detected by the remaining fuel sensor 65. This is the remaining fuel amount at the time of stoppage, and when fuel is supplied, the remaining fuel amount L0 before refueling is stored in the backup RAM. Then, based on the signal from the fuel filler sensor 68, the CPU changes from the state where the fuel filler opening is opened to the closed state, and the remaining fuel detected by the fuel remaining amount sensor 65 at that time. When the amount L1 is larger than the engine remaining fuel amount L0 stored in the backup RAM, it is determined that the current time is “immediately after refueling is completed”.

  According to the above assumption, the current time is “immediately after refueling is completed”. Accordingly, the CPU makes a “Yes” determination at step S210 to proceed to step S220, and inputs an initial value 0 to the time counter T.

  Next, the CPU proceeds to step S230 to determine whether or not the value of the time counter T has exceeded a predetermined time (pump drive time, stirring time) T1. This predetermined time T1 is separately determined by a routine shown in FIG. At the present time, the value of the time counter T is 0 in step S220.

  At this time, if the predetermined time T1 is set to a value larger than 0, the CPU makes a “No” determination at step S230 to proceed to step S240 to operate the electric feed pump 52a. Next, the CPU proceeds to step S250 to increase the value of the time counter T by “1”. Thereafter, the CPU once ends this routine. As a result, the fuel stored in the fuel tank 51a starts to be agitated by the electric feed pump 52a.

  When the CPU starts the process of this routine again after a predetermined time has passed and proceeds to step S210, the CPU proceeds directly from step S210 to step S230 because it is not immediately after the end of refueling. Furthermore, if the value of the time counter T has not reached the predetermined time T1, the CPU executes the processes of steps S240 and S250. Such a process is repeated until the value of the time counter T reaches the predetermined time T1, so that the fuel stored in the fuel tank 51a is continuously stirred by the electric feed pump 52a, and the value of the time counter T is Increasing gradually.

  Thereafter, the value of the time counter reaches a predetermined time T1. At this time, when the CPU starts the process of this routine again and proceeds to step S210, the CPU proceeds to step S230 via step S210 and determines “Yes” in step S230. That is, the CPU determines that the fuel in the fuel tank 51a need not be stirred any further. Then, the CPU proceeds to step S260 to stop the operation of the electric feed pump 52a, and thereafter ends this routine. In this way, the electric feed pump 52a is operated until a predetermined time T1 has passed since the end of refueling, whereby the fuel in the fuel tank 51a is “operating time T1 and the pumping amount per unit time of the electric feed pump 52a. Is agitated by the amount of agitation according to the product.

  If the predetermined time T1 is set to “0”, when the CPU proceeds to step S230 immediately after refueling, the CPU determines “Yes” in step S230 and proceeds to step S260. Therefore, in this case, the electric feed pump 52a cannot be operated.

  Next, a method for calculating the predetermined time T1 referred to in step S230 of the above-described fuel agitation routine will be described. The CPU always monitors whether or not the current time is immediately after fuel supply, and determines that the current time is immediately after fuel supply, the “target stirring time (stirring amount) calculation routine shown in the flowchart of FIG. 3”. Is executed only once prior to the execution of the fuel agitation routine of FIG.

  Therefore, when the fuel supply is completed, the CPU starts the process from step S300 in FIG. 3 and proceeds to step S310, where “the value Nm0 representing the fuel property value before refueling” (hereinafter, “the fuel property value Nm0 before refueling”). Is read from the backup RAM. Next, the CPU proceeds to step S320, and calculates a value Nm1 representing the fuel property value after refueling (hereinafter referred to as “fuel property value Nm1 after refueling”). Note that the CPU stores the newly calculated fuel property value Nm1 after refueling in the backup RAM as “fuel property value Nm0 before refueling” in step S370 to be described later.

  Here, the fuel property value will be described. The fuel property value is a value that changes in accordance with a mixing ratio of “light oil, gasoline, and alcohol” that is assumed to be used (fuel supply) as a fuel, and is a value that represents the property of the fuel. The fuel property value is, for example, “octane number” when the engine 10 is a spark ignition type engine, and it is assumed that gasoline alone, alcohol alone, or fuel in which gasoline and alcohol are mixed is used. Also good. The fuel property value may be the stoichiometric air-fuel ratio of the fuel used. As described above, in the first embodiment, it is assumed that either light oil or gasoline is supplied to the fuel tank 51a in the engine 10, and the cetane number is used as the fuel property value.

  A specific method for obtaining the fuel property value (cetane number) in step 320 will be described below. Here, the fuel property value may be obtained by, for example, a well-known fuel property estimation method as described in JP-A-2008-163901.

  FIG. 4 is a graph showing the relationship between temperature and vapor pressure (that is, vapor pressure characteristics) for various fuels. In FIG. 4, line Cg shows the vapor pressure characteristic of gasoline, and line Cd shows the vapor pressure characteristic of light oil. The electric control device 61 stores these vapor pressure characteristics as a map in the ROM.

By the way, in general, when the temperature of the gas in the tank is a certain temperature (t = t0), as shown in FIG. 5, the pressure of the gas in the tank is “all the fuel after refueling consisting only of light oil and gasoline. It increases in proportion to the mixing ratio x representing the ratio of gasoline to be occupied. Therefore, as is apparent from FIG. 5, when the acquired value of the tank internal pressure sensor 66 is Pm, the mixing ratio x is obtained by the following equation (1). That is, the vapor pressure characteristic of the mixed fuel of light oil and gasoline having a mixing ratio x changes as shown by the line Cm in FIG.

  Therefore, in step S320, the CPU first acquires output values of the tank internal pressure sensor 66 and the tank internal temperature sensor 67. Next, the CPU reads “gasoline vapor pressure Pg and light oil vapor pressure Pd” in the output value of the tank temperature sensor 67 from the map shown in FIG. Then, the CPU substitutes the output value Pm of the tank internal pressure sensor 66 and the “gasoline vapor pressure Pg and light oil vapor pressure Pd” read out from the map into the equation (1), thereby obtaining the mixing ratio x. calculate.

Thereafter, the CPU substitutes the fuel property value Nm1 after refueling by substituting the calculated mixing ratio x, the known fuel property value Nmg of gasoline, and the known fuel property value Nmd of light oil into the following equation (2). calculate.

  Next, the CPU proceeds to step S330, and determines whether or not the pre-fuel supply fuel property value Nm0 and the post-fuel supply fuel property value Nm1 acquired in steps S310 and S320, respectively.

  At this time, if Nm1 is different from Nm0, the CPU makes a “Yes” determination at step S330 to proceed to step S340, where the remaining fuel amount (fuel remaining amount after refueling) L1 in the fuel tank 51a after refueling. Is acquired from the fuel remaining amount sensor 65.

  Next, the CPU proceeds to step S350, and applies the acquired post-refueling fuel remaining amount L1 to the “map that defines the relationship between the remaining fuel amount after refueling and the predetermined time T1” stored in the ROM in advance. A predetermined time T1 is calculated. The longer the fuel remaining amount L1 after refueling, the longer the time for stirring the fuel by operating the electric feed pump 52a (that is, increasing the amount of stirring). In other words, the smaller the remaining fuel amount L1 after refueling, the shorter the fuel agitation time (that is, the smaller the agitation amount), the more uniform the fuel. Therefore, the “map that defines the relationship between the remaining fuel amount after refueling and the predetermined time T1” is set such that the predetermined time T1 for operating the electric feed pump 52a increases as the remaining fuel amount L1 after refueling increases. . Thereafter, the CPU proceeds to step S370.

  On the other hand, if Nm1 is equal to Nm0, the refueled fuel is the same type of fuel as the pre-refueling fuel remaining in the fuel tank a51 before refueling, and therefore it is not necessary to agitate the fuel after refueling by the electric feed pump 52a. . If Nm1 is equal to Nm0, the CPU makes a “No” determination at step S330 to proceed to step S360, and sets the predetermined time T1 to 0. Thereafter, the CPU proceeds to step 370.

  In step S370, the CPU stores the fuel property value Nm1 after refueling calculated in step S320 in the backup RAM as the “fuel property value Nm0 before refueling” for the next calculation, and ends this routine.

  As described above, when the refueling fuel and the fuel before refueling have different fuel property values, the control device according to the first embodiment has the electric feed pump 52a for a longer time as the remaining fuel amount L1 after refueling increases. The amount of agitation is further increased by operating. Therefore, since the electric feed pump 52a is operated for an appropriate time, it is possible to avoid wasting energy for fuel agitation.

(Second Embodiment)
Next, a second embodiment according to the present invention will be described. The second embodiment is different from the first embodiment only in that the CPU of the electric control device executes the “target stirring time (stirring amount) calculation routine shown in FIG. 6” instead of the routine shown in FIG. Is different. Therefore, hereinafter, this difference will be mainly described. Of the steps shown in FIG. 6, steps that perform the same processing as the steps shown in FIG. 3 are given the same reference numerals as those of FIG. 3, and detailed descriptions thereof are omitted as appropriate. Also in the second embodiment, it is assumed that either light oil or gasoline is used for the engine 10 as fuel.

  The CPU executes the target agitation time calculation routine shown in FIG. 6 at the same timing as the target agitation time calculation routine in the first embodiment. The CPU acquires the fuel property value Nm0 before refueling, the fuel property value Nm1 after refueling, and the remaining fuel amount L1 after refueling by executing the processes of step S310, step S320, and step S340.

  Next, the CPU proceeds to step S450, and calculates a basic time T0 for calculating the predetermined time T1 based on the post-refueling fuel remaining amount L1 in the fuel tank 51a after refueling acquired in step S340. The process in step S450 is the same process as step S350 in FIG. Therefore, the basic time T0 is calculated so as to become longer as the fuel remaining amount L1 after refueling increases.

Next, the CPU proceeds to step S460, and calculates the fuel property value change rate d by applying the obtained post-fuel supply fuel property value Nm1 and the pre-fuel supply fuel property value Nm0 to the following equation (3). .

Each value in the equation (3) is as follows.
Nmin is a fuel property value of a fuel (minimum property value fuel) that is a single type of fuel among the plurality of types of fuel assumed to be used in the engine 10 and has the smallest fuel property value. is there.
Nmax is a fuel property value of a fuel (maximum property value fuel) that is a single type of fuel of a plurality of types of fuel assumed to be used in the engine 10 and has the largest fuel property value of the same fuel. is there.
As described above, in this embodiment, it is assumed that two types of gasoline and light oil are used, and the fuel property value is a cetane number. Therefore, Nmin is the cetane number Nmg of gasoline, and Nmax is cetane of light oil. The value is Nmd.

  Next, the CPU proceeds to step S470, in which the fuel property value change rate d obtained in step S460 is stored in advance in the “map defining the relationship between the fuel property value change rate d and the correction coefficient k”. Is applied to the correction coefficient k. According to this map, the correction coefficient k is set so as to increase as the fuel property value change rate d approaches 0.5, while toward 0 as the fuel property value change rate d approaches 0 and 1. It is set to be smaller. That is, the correction coefficient k becomes the maximum value “1” when the fuel property value change rate d is 0.5, and becomes the minimum value “0” as the fuel property value change rate d approaches 0 and 1.

  As the fuel property value change rate d approaches 0.5, the difference between the fuel property value of the fuel supply fuel and the fuel property value Nm0 before refueling increases, so the fuel property in the fuel distribution in the fuel tank portion 51 after refueling. The value variation is large. Accordingly, at this time, the correction coefficient k is set so as to increase the amount of stirring by the electric feed pump unit 52. On the other hand, the closer the fuel property value change rate d approaches 0 or 1, the smaller the difference between the fuel property value of the fuel supply fuel and the fuel property value Nm0 before refueling, so in the fuel distribution in the fuel tank portion 51 after refueling. Variations in fuel property values are small. Therefore, at this time, the correction coefficient k is set so as to reduce the amount of stirring by the electric feed pump unit 52.

  Next, the CPU proceeds to step S480, and calculates the predetermined time T1 by multiplying the basic time T0 obtained in step S450 by the correction coefficient k obtained in step S470. The predetermined time T1 calculated in this way is referred to in step S230 of the fuel agitation routine shown in FIG. 2 as in the first embodiment.

  In step S370, the CPU stores the fuel property value Nm1 after refueling in the backup RAM as “fuel property value Nm0 before refueling” for the next calculation, and ends this routine.

  According to the second embodiment, not only the fuel remaining amount L1 after refueling but also the fuel property value change rate d is used when determining the operation time of the electric feed pump 52a. Therefore, since the electric feed pump 52a is operated for an appropriate time so that the variation of the fuel property value in the fuel distribution in the fuel tank 51a after refueling is reduced, useless energy is consumed for stirring the fuel. Can be avoided.

As described above, the control device for an internal combustion engine according to the present invention is
Operation is possible using fuel that is a mixture of multiple fuels with different fuel property values (Nm) representing the properties of the fuel determined according to the type of fuel and stored in one fuel tank (51) A control device for an internal combustion engine,
The fuel property value (Nm0) before refueling, which is the fuel property value of the fuel stored in the fuel tank at the time before refueling the fuel tank, and the fuel at the time after the refueling to the fuel tank After refueling fuel property value (Nm1), which is the fuel property value of the fuel stored in the tank, and after refueling, which is the amount of fuel stored in the fuel tank at the time after the refueling to the fuel tank Information acquisition means (tank internal pressure sensor 66, tank internal temperature sensor 67) for acquiring the remaining amount of fuel (L1);
Stirring means (electric feed pump unit 52) for stirring the fuel stored in the fuel tank;
Based on the pre-fuel supply fuel property value, the post-fuel supply fuel property value, and the post-fuel supply remaining fuel amount acquired by the information acquisition unit, the target value (T1) of the amount of fuel stirred by the stirring unit is determined. And the stirring means stirs the fuel stored in the fuel tank in a period from the time after the refueling to the time when the engine starts operation with the fuel stored in the fuel tank. Stirring amount control means (electric control device 61) for operating the stirring means so as to stir only the target value of the amount.

  That is, the control device for an internal combustion engine according to each embodiment of the present invention is configured such that when fuel is supplied to an internal combustion engine that can be used by mixing a plurality of types of fuel having different fuel properties, before the engine is started, Then, the fuel property value Nm0 of the fuel before refueling remaining in the fuel tank 51a and the fuel property value Nm1 of the fuel after refueling are acquired and compared. When the fuel property value Nm0 before refueling and the fuel property value Nm1 after refueling are different, the electric feed pump 52a provided in the fuel tank portion 51 is operated, and the remaining fuel amount L1 after refueling or the remaining fuel amount L1 after refueling The fuel in the fuel tank 51a is agitated only for a predetermined time T1, which is calculated based on the fuel property value change rate d. As a result, the electric feed pump 52a can be operated for a predetermined time T1, which is determined to be necessary according to the state of the fuel in the fuel tank 51a, to stir the fuel. Therefore, when the fuel is agitated using the electric feed pump 52a, the fuel in the fuel tank 51a is agitated so as to be sufficiently uniform without causing an excessive operation to waste battery power. can do.

  The present invention is not limited to the above embodiment, and various modifications can be employed within the scope of the present invention. For example, the present invention can be applied even when it is assumed that any of light oil, gasoline, and alcohol is used as the fuel in the internal combustion engines according to the above embodiments.

・給油後燃料性状値Ｎｍ１を下記の（５）式に基づいて求める。なお、（５）式の右辺における給油前燃料性状値Ｎｍ０は、（５）式に基づいて前回求められた給油後燃料性状値Ｎｍ１である。

In this case, when it is determined that alcohol is contained in the fuel supply fuel based on the output value of the alcohol concentration sensor 64 (that is, when it is determined that the fuel supplied is a mixed fuel of gasoline and alcohol), What is necessary is just to calculate the fuel property value (cetane number) after refueling as follows.
The alcohol concentration z in the fuel supply fuel is acquired based on the output value of the alcohol concentration sensor 64.
The fuel supply fuel amount Ly is calculated by subtracting the fuel remaining amount L0 before refueling from the fuel remaining amount L1 after refueling.
-Obtain the cetane number Ny of the fuel supply fuel based on the following equation (4). In formula (4), Nma is the cetane number of the alcohol.

-Obtain the fuel property value Nm1 after refueling based on the following equation (5). In addition, the fuel property value Nm0 before refueling on the right side of the equation (5) is the fuel property value Nm1 after refueling obtained previously based on the equation (5).

  Furthermore, the present invention can also be applied to a spark ignition type internal combustion engine corresponding to two types of fuels, gasoline and alcohol. In this case, the fuel property of the mixed fuel may be estimated by detecting the alcohol concentration with an alcohol concentration sensor and acquiring the mixing ratio of gasoline and alcohol.

  Furthermore, in the embodiment according to the present invention, the cetane number indicating the ignitability of the fuel is adopted as the index value indicating the fuel property value. However, the index value indicating the other properties and various mixed fuel concentrations is acquired. May be substituted. For example, regarding the various fuels used, in addition to the above-mentioned octane number and theoretical air-fuel ratio, the fuel index value may be determined in consideration of the level of evaporability and the level of heat generation.

  In addition, the device for stirring the fuel in the fuel tank unit 51 may not be the electric feed pump 52a, but may be an electric fuel stirring device (for example, an electric propeller) provided separately from the electric feed pump 52a. May be. Furthermore, although the said embodiment controlled the amount of stirring by the operating time of the electric feed pump 52a, you may control by changing the pumping amount of the electric feed pump 52a. Further, the information acquisition means may be configured to acquire the fuel property value, the amount of fuel supply, and the like based on a signal transmitted from the “fueling device provided at a gas station or the like” to the electric control device 61. Good.

  DESCRIPTION OF SYMBOLS 10 ... Internal combustion engine, 51 ... Fuel tank part, 52 ... Electric feed pump part, 61 ... Electric control apparatus, 64 ... Alcohol concentration sensor, 65 ... Fuel remaining amount sensor, 66 ... Tank internal pressure sensor, 67 ... Tank internal temperature sensor

Claims (5)

A control device for an internal combustion engine that can be operated by using a fuel in which a plurality of types of fuels having different fuel property values representing the properties of the fuel determined according to the type of fuel are mixed and stored in one fuel tank Because
The fuel property value before refueling, which is the fuel property value of the fuel stored in the fuel tank at the time before refueling the fuel tank, and the fuel property value of the fuel replenished to the fuel tank by the refueling At least one of two values of a fuel property value and a fuel property value after refueling that is a fuel property value of fuel stored in the fuel tank at a time after the fueling to the fuel tank, and the fuel Information acquisition means for acquiring the amount of fuel after refueling, which is the amount of fuel stored in the fuel tank at a time after the refueling of the tank;
Stirring means for stirring the fuel stored in the fuel tank;
The target value of the amount of fuel agitated by the agitating means is determined by two values: the acquired pre-fuel supply fuel property value, the acquired fuel supply fuel property value, and the acquired post-fuel supply fuel property value. And calculating based on at least one of them and the acquired post-refueling fuel remaining amount, and from the time after the refueling to the time when the engine starts operation with the fuel stored in the fuel tank Stirring amount control means for operating the stirring means so that the stirring means stirs the fuel stored in the fuel tank by the target value of the stirring amount during the period of
The control apparatus of the internal combustion engine provided with. The control apparatus for an internal combustion engine according to claim 1,
The stirring amount control means includes
When the acquired pre-fuel supply fuel property value is different from the acquired fuel supply fuel property value, or the acquired pre-fuel supply fuel property value and the acquired post-fuel supply fuel property value are If it is a different value, the target value of the agitation amount is calculated so that the target value of the agitation amount increases as the remaining amount of fuel after refueling increases.
When the acquired pre-fuel supply fuel property value and the acquired fuel supply fuel property value are the same value, or the acquired pre-fuel supply fuel property value and the acquired post-fuel supply fuel property value are The control apparatus for an internal combustion engine, wherein the target value of the stirring amount is set to 0 when the values are the same. The control apparatus for an internal combustion engine according to claim 1,
The stirring amount control means includes
Of the plurality of types of fuel assumed to be used in the engine, a single type of fuel having the smallest fuel property value of the same fuel and a plurality of types of fuel of the same type The fuel property value after refueling and the before fueling with respect to the magnitude of the difference in fuel property value with the maximum property value fuel that is the fuel with the largest fuel property value of the other single type of fuel The target value of the agitation amount increases as the fuel property value change rate represented by the ratio of the difference between the fuel property value and the fuel property value approaches 50%, and the remaining fuel amount after refueling increases. The control device for an internal combustion engine, wherein the target value of the stirring amount is calculated so that the target value of the stirring amount becomes large. The control apparatus for an internal combustion engine according to claim 2 or 3,
The control apparatus for an internal combustion engine, wherein the fuel property value is a cetane number. The control apparatus for an internal combustion engine according to claim 4,
The information acquisition means includes
A pressure sensor that actually detects the pressure of the gas in the fuel tank;
A temperature sensor that actually detects the temperature of the gas in the fuel tank;
Including
Based on the gas pressure and the gas temperature detected before the refueling, the cetane number of the fuel stored in the fuel tank at the time prior to the refueling is calculated as the fuel property value before refueling. And the cetane number of the fuel stored in the fuel tank at the time after the refueling based on the pressure of the gas and the temperature of the gas detected at the time after the refueling. Configured to estimate the fuel property value after refueling,
Control device for internal combustion engine.

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