JP2010014070A - Fuel injection control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel injection control device capable of appropriately controlling a quantity of fuel supplied into a cylinder of a vehicle using alcohol fuel by correcting a fuel injection quantity to an intake port when a temperature of the inside of an intake port is near a boiling point of alcohol fuel. <P>SOLUTION: An ECU 100 can calculates an evaporated fuel quantity from an adhesion fuel quantity of alcohol fuel injected to an intake port 8 by being provided with a fuel injection means, an adhesion fuel quantity calculation means, an evaporated fuel quantity calculation means, an evaporated fuel quantity correction means, and a fuel injection quantity correction means. The calculation of the evaporated fuel quantity using evaporation characteristics of alcohol fuel can be accurately executed by correcting the calculated evaporated fuel quantity based on an engine cooling water temperature when a temperature of a wall surface of the intake port 8 is near the boiling point of alcohol. The fuel injection quantity of the internal combustion engine when using 100% alcohol fuel can be optimally controlled by correcting the fuel injection quantity based on the correction quantity of the calculated evaporated fuel quantity. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a fuel injection control device. In particular, the present invention relates to a technique for controlling the fuel injection amount of a vehicle that uses a single component alcohol alone as fuel.

  In recent years, a system that can simultaneously use alcohol as an alternative fuel in addition to gasoline fuel has been put into practical use due to air pollution and changes in crude oil conditions. A vehicle (Flexible Fuel Vehicle) equipped with this system can travel not only with gasoline fuel but also with a mixed fuel of gasoline and alcohol, or with 100% alcohol.

  Such a FFV internal combustion engine employs a port injection type in the same manner as a conventional gasoline internal combustion engine, and an alcohol-containing fuel is injected into the intake port by an injector disposed in the intake passage. The fuel injected in this way is sucked into the combustion chamber together with air by introducing the in-cylinder negative pressure to the intake port as the intake valve opens. Part of the fuel injected into the intake port adheres to the wall surface of the intake port, and part of the attached fuel evaporates. In the steady state, the fuel adhesion amount and the evaporated fuel amount are constant, and the amount of fuel sucked into the combustion chamber is equal to the amount of injected fuel.

  However, during the transient operation of the internal combustion engine, the amount of adhering fuel and the amount of evaporated fuel increase and decrease due to changes in the intake air amount and the fuel injection amount. While this increase / decrease occurs, there is a difference between the amount of fuel sucked into the combustion chamber and the amount of fuel injected. Therefore, in order to suck the fuel amount required during the transient operation into the combustion chamber, it is necessary to correct the fuel injection amount based on the amount of fuel adhering to the wall surface of the intake port and the amount of evaporated fuel. Become.

  In order to suppress such a difference between the fuel injection amount and the fuel amount sucked into the cylinder, a technique for correcting the amount of fuel adhering to the port wall surface of the FFV engine based on the vapor pressure of the fuel is disclosed in Patent Document 1. Is disclosed.

  Also, Patent Documents 2 to 4 disclose techniques for correcting the adhesion rate of injected fuel to an intake port and the residual rate of adhered fuel in a gasoline engine using a fuel behavior model.

JP 2006-220010 A JP 2007-187071 A JP 2004-162588 A JP 2007-263047 A

  Here, the distillation behavior of a fuel that is a mixture of gasoline and alcohol shows a continuous distillation behavior due to the mixing of various components, whereas a single component alcohol is a discontinuous that evaporates all at once at its boiling point. Shows a typical distillation behavior (see FIG. 2). Therefore, the technique of Patent Document 1 has a problem that when the fuel is 100% alcohol, it is difficult to estimate the amount of fuel adhering to the wall surface of the intake port near the boiling point of the alcohol fuel from the vapor pressure of the fuel. . Patent Documents 2 to 4 are techniques for correcting the fuel injection amount on the premise of a gasoline engine. In order to apply to an internal combustion engine using alcohol fuel (especially 100% alcohol), the distillation behavior of alcohol is changed. Significant improvements are needed. As described above, in the conventional technology, there is a problem that it is difficult to accurately determine the amount of fuel adhering to the wall surface of the intake port and the amount of evaporated fuel with respect to the fuel injection control when using 100% alcohol fuel. .

  The present invention has been made in view of the above points, and corrects the fuel injection amount to the intake port when the temperature inside the intake port is near the boiling point of the alcohol fuel, so that the cylinder of the vehicle using the alcohol fuel is corrected. It is an object of the present invention to provide a fuel injection control device capable of optimally controlling the amount of fuel supplied inside.

  In order to solve this problem, a fuel injection control device according to the present invention is a fuel injection control device for an internal combustion engine comprising fuel injection means for injecting a single component alcohol fuel into an intake port, wherein the fuel injection means An attached fuel amount calculating means for calculating the amount of attached fuel adhering to the intake port among the fuel injected by the fuel, and an amount of evaporated fuel evaporating between the fuel adhering to the intake port until the next fuel injection An evaporative fuel amount calculating means, a cooling water temperature detecting means for detecting a cooling water temperature of the internal combustion engine, and an evaporative fuel amount for correcting a calculation result of the evaporative fuel amount calculating means based on a detection result of the cooling water temperature detecting means A fuel injection amount correction that corrects the fuel injection amount of the fuel injection unit based on the correction unit, the calculation result of the attached fuel amount calculation unit, and the correction result of the evaporated fuel amount correction unit. Characterized in that it comprises a means.

  With this configuration, the amount of fuel adhering to the intake port of 100% alcohol fuel and the amount of evaporated fuel are accurately calculated using the evaporation characteristics of alcohol, and the fuel injection amount is corrected based on the calculation result. Therefore, the fuel injection amount of the internal combustion engine when using 100% alcohol fuel can be optimally controlled. The adhering fuel amount calculating means and the evaporated fuel amount calculating means according to the present invention calculate the adhering fuel amount to the intake port wall surface and the adhering fuel evaporating fuel amount from the operating state of the internal combustion engine. Here, since the port wall surface temperature of the intake port is usually substantially the same as the engine coolant temperature, the intake port wall surface temperature can be obtained by detecting the engine coolant temperature. Therefore, by correcting the calculated amount of evaporated fuel based on the detection result of the engine coolant temperature, when the intake port temperature is near the boiling point of alcohol, the amount of evaporated fuel can be calculated accurately using the evaporation characteristics of alcohol fuel. Can be executed. Furthermore, the fuel injection amount of the internal combustion engine when using 100% alcohol fuel can be optimally controlled by correcting the fuel injection amount based on the obtained correction value of the evaporated fuel amount.

  As described above, the fuel consumption and the exhaust emission of the vehicle can be improved by optimally controlling the fuel injection amount during the transient operation. Furthermore, the startability of the internal combustion engine can be improved.

  In particular, the fuel injection control device according to the present invention includes an intake valve attached fuel amount calculating means for calculating an amount of attached fuel adhering to the intake valve out of fuel injected by the fuel injection means, and a fuel adhering to the intake valve. Among them, an intake valve evaporated fuel amount calculating means for calculating the amount of evaporated fuel evaporated until the next fuel injection, an intake valve wall surface temperature detecting means for detecting a wall surface temperature of the intake valve of the vehicle, and the intake valve Intake valve evaporated fuel amount correcting means for correcting the calculation result of the intake valve evaporated fuel amount calculating means based on the detection result of the wall surface temperature detecting means, and the fuel injection amount correcting means is the attached fuel amount calculating means. Of the fuel injection means based on the calculation result of the intake valve attached fuel amount calculation means, the correction result of the evaporated fuel amount correction means, and the correction result of the intake valve evaporated fuel amount correction means. Fuel injection It can be characterized in that corrected.

  By adopting such a configuration, not only the evaporation behavior of the fuel adhering to the wall surface of the intake port but also the evaporation behavior of the fuel adhering to the wall surface of the intake valve is considered more accurately. The amount and evaporation timing can be calculated. Therefore, the fuel injection control of the internal combustion engine when using alcohol fuel can be executed with higher accuracy, so that the fuel consumption and exhaust emission of the vehicle can be further improved and the startability of the internal combustion engine is improved. Can do.

  The fuel injection control device according to the present invention includes an attached fuel rate calculating means for calculating an attached fuel rate that adheres to the intake port among fuels injected by the fuel injection means, and a fuel that adheres to the intake port. Evaporative fuel rate calculating means for calculating an evaporative fuel rate that evaporates until the next fuel injection, and the attached fuel amount calculating means includes a fuel injection amount previously injected by the fuel injector and the attached fuel rate. Calculating the adhering fuel amount based on the calculation result of the calculating means, the calculation result previously calculated by the adhering fuel amount calculating means, and the residual fuel rate obtained from the calculation result of the evaporated fuel rate calculating means; Can be a feature.

  The rate of fuel adhering to the intake port wall surface and the rate of evaporated fuel correspond to the operating state of the internal combustion engine. Therefore, the fuel injection amount injected into the intake port is multiplied by the adhered fuel rate calculated from the operating state of the internal combustion engine, and the residual adhered fuel amount that has not evaporated with the fuel adhered in the previous cycle is obtained. Thus, the amount of fuel attached to the intake port wall surface can be calculated. In this way, the fuel injection amount to the intake port can be controlled with higher accuracy using the fuel behavior model.

  The fuel injection control device of the present invention further comprises an evaporated fuel rate calculating means for calculating an evaporated fuel rate that evaporates between fuels adhering to the intake port until the next fuel injection, and the evaporated fuel amount calculating means However, the evaporated fuel amount may be calculated based on a calculation result of the attached fuel amount calculating unit and a calculation result of the evaporated fuel rate calculating unit.

  The evaporated fuel rate of the fuel adhering to the intake port wall surface corresponds to the operating state of the internal combustion engine. Therefore, the evaporated fuel amount from the intake port can be calculated by multiplying the adhered fuel amount by the evaporated fuel rate calculated from the operating state of the internal combustion engine. In this way, the fuel injection amount to the intake port can be controlled with higher accuracy using the fuel behavior model.

  Furthermore, the fuel injection control device according to the present invention is such that the fuel injection amount correction means is configured to provide fuel for the fuel injection means when the detection result of the cooling water temperature detection means is between the evaporation start temperature and the boiling point of the fuel. It is possible to correct the injection amount.

  When the temperature of the intake port wall surface is lower than the boiling point of the alcohol fuel, the fuel adhering to the intake port wall surface does not evaporate and leaks into the combustion chamber. Further, when the temperature of the intake port wall surface exceeds the boiling point of the alcohol fuel, all the fuel injected into the intake port evaporates, and there is no fuel adhering to the intake port wall surface. In this case, since there is no alcohol fuel that evaporates at the intake port, the amount of fuel required for driving the vehicle may be injected into the intake port. On the other hand, when the temperature of the intake port wall surface is the alcohol fuel evaporation start temperature (boiling point -α ° C), the fuel adhering to the intake port wall surface gradually begins to evaporate, and the intake port wall surface temperature reaches the boiling point of alcohol fuel. In this case, all the fuel adhering to the wall surface of the intake port evaporates all at once. Therefore, by correcting the fuel injection amount to the intake port between the evaporation start temperature of the alcohol fuel and the boiling point at which the evaporation is completed, the fuel injection control of the internal combustion engine when using the alcohol fuel has higher accuracy. Therefore, the fuel consumption and exhaust emission of the vehicle can be further improved, and the startability of the internal combustion engine can be improved.

  In the fuel injection control device of the present invention, when the fuel injection amount correction means has a detection result of the intake valve wall surface temperature detection means between the evaporation start temperature and the boiling point of the fuel, the fuel injection means The fuel injection amount is corrected.

  When the internal combustion engine starts, the temperature in the intake port increases as the temperature of the internal combustion engine increases due to warm-up. Here, since the temperature of the intake valve wall usually rises faster than the intake port wall, the fuel adhering to the intake valve evaporates faster than the alcohol fuel adhering to the intake port. Therefore, by detecting the temperature of the wall surface of the intake valve and correcting the fuel injection amount based on the detection result, the evaporated fuel amount of the attached fuel in the intake port and the evaporation timing can be calculated more accurately.

  The fuel injection control device of the present invention may be characterized in that the cooling water temperature detecting means is provided in the vicinity of the intake port.

  The port wall surface temperature of the intake port can be obtained by detecting the engine cooling water temperature, but the intake port wall surface temperature can be detected more accurately by making the engine cooling water temperature detection location near the intake port. . Therefore, the fuel injection control of the internal combustion engine when using alcohol fuel can be executed with higher accuracy, so that the fuel consumption and exhaust emission of the vehicle can be further improved and the startability of the internal combustion engine is improved. Can do.

  According to the fuel injection control device of the present invention, the fuel injection amount to the intake port can be corrected based on the evaporated fuel amount when the wall surface temperature of the intake port and the intake valve is near the boiling point of the alcohol fuel. It is possible to optimally control the amount of fuel supplied into the cylinder of a vehicle that uses a single component alcohol fuel alone.

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings.

  Embodiment 1 of the present invention will be described with reference to the drawings. FIG. 1 is an explanatory diagram showing a schematic configuration of an engine 1 incorporating a fuel injection control device of the present invention. FIG. 1 shows only the configuration of one cylinder of the engine.

  The engine 1 is a multi-cylinder engine mounted on a vehicle, and each cylinder includes a piston 2 constituting a combustion chamber 1a. The piston 2 of each combustion chamber 1a is connected to the shaft of the crankshaft 3 which is an output shaft via a connecting rod 4, and the reciprocating motion of each piston 2 is converted into rotation of the crankshaft 3 by the connecting rod 4. The

  A crank angle sensor 5 is disposed near the axis of the crankshaft 3. The crank angle sensor 5 is configured to detect the rotation angle of the three crankshaft axes, and outputs the detection result to the ECU 100. Thereby, ECU100 can acquire the information regarding a crank angle. Further, a crank sprocket 6 is connected to one end of the crankshaft 3. The crank sprocket 6 rotates at the same cycle as the crankshaft 3. As the crank sprocket 6, a known sprocket having a plurality of teeth arranged on the outer periphery can be used. The crank sprocket 6 is meshed with a pinion gear of a starter motor 7 that is started when the engine 1 is started, and the engine 1 is cranked by the rotation of the ring gear accompanying the starter motor 7 being started.

  Connected to the combustion chamber 1a of each cylinder are an intake port 8 communicating with the combustion chamber 1a and an intake passage 9 connected to the intake port 8 and leading intake air from the intake port 8 to the combustion chamber 1a. . Further, each cylinder of the combustion chamber 1a is connected to an exhaust port 10 communicating with the combustion chamber 1a and an exhaust passage 11 for guiding the exhaust gas generated in the combustion chamber 1a to the outside of the engine. Further, the exhaust passages 11 connected to the respective cylinders merge on the downstream side to form a single merged exhaust passage 400.

  A plurality of intake valves and exhaust valves are provided corresponding to the intake passage and exhaust passage of the combustion chamber 1a of each cylinder. FIG. 1 shows one intake passage, one exhaust passage, one intake valve, and one exhaust valve. An intake valve 12 is disposed in each intake port 8 of the combustion chamber 1a, and an intake camshaft 13 for opening and closing the intake valve 12 is disposed. Further, an exhaust valve 14 is disposed at each exhaust port 10 of the combustion chamber 1a, and an exhaust camshaft 15 for opening and closing the exhaust valve 14 is disposed.

  The intake valve 12 and the exhaust valve 14 are opened and closed by the rotation of the intake camshaft 13 and the exhaust camshaft 15 to which the rotation of the crankshaft 3 is transmitted by a coupling mechanism (for example, a timing belt, a timing chain, etc.). 10 and the combustion chamber 1a are communicated and blocked. The phases of the intake valve 12 and the exhaust valve 14 are expressed with reference to the crank angle.

  The intake camshaft 13 has an electric VVT mechanism 16 which is a variable valve mechanism (hereinafter referred to as a VVT mechanism). The electric VVT mechanism 16 rotates the intake camshaft 13 with the electric motor 17 in accordance with an instruction from the ECU 100. As a result, the rotational phase of the intake camshaft 13 relative to the crankshaft 3 is changed, so that the valve timing of the intake valve 12 is changed. In this case, the rotational phase of intake camshaft 13 is detected by intake cam angle sensor 18 and output to ECU 100. Thereby, the ECU 100 can acquire the phase of the intake camshaft and can acquire the phase of the intake valve 12. Further, the phase of the intake camshaft 13 is expressed with reference to the crank angle.

  Further, the exhaust camshaft 15 has a hydraulic VVT mechanism 19. The hydraulic VVT mechanism 19 rotates the exhaust camshaft 15 with an oil control valve (hereinafter referred to as OCV) 20 in accordance with an instruction from the ECU 100. As a result, the rotational phase of the exhaust camshaft 15 relative to the crankshaft 3 is changed, so that the valve timing of the exhaust valve 14 is changed. In this case, the rotational phase of the exhaust camshaft 15 is detected by the exhaust cam angle sensor 21 and output to the ECU 100. Thereby, the ECU 100 can acquire the phase of the exhaust camshaft and the phase of the exhaust valve 14. Further, the phase of the exhaust camshaft 15 is expressed with reference to the crank angle.

  An air flow meter 22 that detects the amount of intake air passing through the intake passage 9 is installed in the intake passage 9 of the engine 1. A throttle valve 23 and a throttle position sensor 24 are installed in the intake passage 9. The air flow meter 22 and the throttle position sensor 24 output respective detection results to the ECU 100. Thereby, the ECU 100 can recognize the intake air amount sucked into the intake port 8 and the combustion chamber 1a.

  Each intake port of the engine 1 is provided with an injector 300. The injector 300 is supplied with high-pressure fuel through a fuel pipe from a fuel pump (not shown), and injects and supplies fuel to the intake port 8 according to an instruction from the ECU 100. The ECU 100 determines the fuel injection amount and the injection timing based on the intake air amount from the air flow meter 22 and the throttle position sensor 24 and the cam shaft rotational phase information from the intake cam angle sensor 18 and sends a signal to the injector 300. The injector 300 injects fuel at a high pressure at the fuel injection amount / injection timing instructed to the intake port 8 in accordance with a signal from the ECU 100. The high-pressure injected fuel is atomized and mixed with intake air, becomes a mixed gas suitable for combustion of the engine 1, and is supplied to the combustion chamber 1a when the intake valve 12 is opened. The leaked fuel from the injector 300 is returned to a fuel tank (not shown) through the relief pipe.

As alcohol fuel, methanol (CH ₃ OH, boiling point 64.7 ° C., density 0.79 g · cm ⁻³ ) or ethanol (C ₂ H ₅ OH, boiling point 78.3 ° C., density 0.79 g · cm ^−3). ) Can be applied. The engine 1 of this embodiment uses single component ethanol as fuel. The stoichiometric air-fuel ratio when the gasoline is 100% (ethanol 0%) is 14.7, whereas the stoichiometric air-fuel ratio when the fuel is 100% ethanol is 9.0. Here, the distillation behavior of ethanol and gasoline is shown in FIG. Gasoline with multiple components shows continuous distillation characteristics with respect to temperature, whereas single component ethanol evaporates at its boiling point (78.3 ° C), so discontinuous distillation Show properties. Therefore, when 100% ethanol fuel is used, the fuel adhering when the temperature of the wall surface of the intake port 8 is lower than the boiling point of ethanol starts to gradually evaporate from the vicinity of the boiling point of ethanol. When it reaches the boiling point, it evaporates all at once. When the temperature of the wall surface of the intake port 8 exceeds the boiling point of ethanol, all of the fuel injected into the intake port 8 evaporates, so there is no fuel adhering to the wall surface of the intake port 8. By utilizing this characteristic, the amount of fuel adhering to the wall surface of the intake port 8 and the amount of evaporated fuel when the temperature of the wall surface of the intake port 8 is near the boiling point of ethanol (78.3-α ° C.) to the boiling point are accurately determined. By recognizing, the amount obtained by subtracting the evaporated fuel amount from the required fuel injection amount can be set as the next fuel injection amount.

  The combustion chamber 1a of each cylinder is provided with a spark plug 26, and the ignition timing of the spark plug 26 is adjusted by an igniter 27. The mixed gas flowing in from the intake port 8 is compressed in the combustion chamber 1 a by the upward movement of the piston 2. The ECU 100 determines the ignition timing based on the position of the piston 2 from the crank angle sensor 5 and the cam shaft rotation phase information from the intake cam angle sensor 18 and sends a signal to the igniter 27. The igniter 27 energizes the spark plug 26 with electric power from the battery 200 at the instructed ignition timing in accordance with a signal from the ECU 100. The spark plug 26 is ignited by electric power from the battery 200, ignites the compressed mixed gas, expands the inside of the combustion chamber 1a, and lowers the piston 2. By changing this to the axial rotation of the crankshaft 3 via the connecting rod 4, the engine 1 obtains power. When the exhaust valve 14 is opened, the exhaust gas after combustion merges in the merged exhaust passage 400 through the exhaust port 10 and the exhaust passage 9, passes through the purification catalyst 401, and is discharged to the outside of the engine 1.

  The exhaust passages 9 of the cylinders merge downstream to form a merged exhaust passage 400, and a purification catalyst 401 is provided at the end of the merged exhaust passage 400. The purification catalyst 401 is used to purify the exhaust gas of the engine 1. For example, a three-way catalyst or a NOx occlusion reduction type catalyst is applied, and these purification catalysts 401 are different depending on the displacement of the engine 1, the use area, and the like. May be installed in combination. The purification catalyst 401 is provided with a catalyst temperature sensor 402. The ECU 100 can recognize the temperature of the purification catalyst 401 by receiving a signal from the catalyst temperature sensor 402 and determine whether or not the purification catalyst 401 is in the active temperature range.

  A water jacket is provided around the combustion chamber 1a, and engine cooling water for cooling the combustion chamber 1a circulates inside the water jacket (not shown). Further, the water jacket is provided with a water temperature sensor 28 for measuring the engine cooling water temperature (Tw). Here, since the port wall surface temperature of the intake port 8 is normally substantially the same as the engine cooling water temperature Tw, the ECU 100 can apply Tw received from the water temperature sensor 28 as the wall surface temperature of the intake port 8. The water temperature sensor 28 corresponds to engine cooling water temperature detecting means for detecting the cooling water temperature of the engine 1.

The battery 200 is a secondary battery using lead dioxide (PbO ₂ ) as a positive electrode, spongy lead (Pb) as a negative electrode, and dilute sulfuric acid (H ₂ SO ₄ ) as an electrolyte, and a charge / discharge cycle depending on their chemical reaction. To implement. When the power generation amount of an alternator (not shown) exceeds the power usage amount of each electrical component, the battery 200 charges the excess power and stores it in the battery. The battery 200 uses the electric power stored in the battery 200 in order to operate the starter motor 7 when the engine 1 is started or to properly operate electrical components such as the ECU 100 while the vehicle is running. Discharge. As the battery 200, for example, a 12 [V] system can be applied, but a high voltage specification such as a 42 [V] system can also be applied.

  The ECU 100 is a computer including a CPU (Central Processing Unit) that performs arithmetic processing, a ROM (Read Only Memory) that stores programs and the like, and a RAM (Random Access Memory) that stores data and the like. The ECU 100 reads the detection results of the crank angle sensor 5, the cam angle sensors 18 and 21, the air flow meter 22, the throttle position sensor 23 and the water temperature sensor 28, and operates the VVT mechanisms 16 and 19, the injector 300, and the spark plug 26. The operation operation of the engine 1 such as ignition timing is integratedly controlled. Further, the ECU 100 calculates the amount of attached fuel that adheres to the wall surface of the intake port 8 among the fuel injected from the injector 300. Then, the ECU 100 calculates the amount of evaporated fuel that evaporates between the fuel adhering to the wall surface of the intake port 8 until the next fuel injection. Further, the ECU 100 corrects the calculated evaporated fuel amount based on the signal from the water temperature sensor 28. Then, ECU 100 corrects the fuel injection amount of injector 300 based on the obtained correction value of the evaporated fuel amount. The ECU 100 corresponds to an attached fuel amount calculating means, an evaporated fuel amount calculating means, an evaporated fuel amount correcting means, and a fuel injection amount correcting means.

[Necessity of fuel injection amount correction]
FIG. 3 is an explanatory diagram showing a schematic configuration during fuel injection of the engine 1. FIG. 3 shows only the configuration of one cylinder of the engine. When the engine 1 is started, ethanol fuel is injected into the intake port 8 by the injector 300 disposed in the intake passage 9. The ethanol fuel injected in this manner is sucked into the combustion chamber 1 a together with air by introducing the in-cylinder negative pressure to the intake port 8 as the intake valve 12 is opened, but is injected into the intake port 8. Part of the fuel that has been deposited adheres to the wall surface of the intake port 8 or the like. Further, the wall surface temperature of the intake port 8 increases as the warm air advances.

  In this case, the behavior of the ethanol fuel attached to the wall surface of the intake port 8 is as follows: (1) When the temperature of the wall surface of the intake port 8 is lower than the ethanol evaporation start temperature, the fuel attached to the wall surface of the intake port 8 does not evaporate. The liquid drip into the combustion chamber 1a. (2) When the temperature of the wall surface of the intake port 8 is near the boiling point of ethanol (evaporation start temperature), the fuel adhering to the wall surface of the intake port 8 gradually starts to evaporate. (3) When the temperature of the wall surface of the intake port 8 reaches the boiling point of ethanol, all the fuel adhering to the wall surface of the intake port 8 evaporates all at once. (4) When the temperature of the wall surface of the intake port 8 exceeds the boiling point of ethanol, all the fuel injected into the intake port 8 evaporates, and there is no fuel adhering to the wall surface of the intake port 8. Therefore, in the above cases (1) and (4), since there is no ethanol fuel that evaporates at the intake port 8, the ECU 100 instructs the injector 300 to inject the fuel amount required for driving the vehicle into the intake port 8. Just go to On the other hand, in the cases (2) and (3), when the ECU 100 gives an instruction to inject the fuel amount required for driving the vehicle into the intake port 8, the ECU 100 sets the intake port 8 in addition to the injected fuel from the injector 300. Since the evaporated fuel is added, the amount of fuel sucked into the combustion chamber 1a becomes excessive.

  Therefore, in order to suck the amount of fuel required during transient operation into the combustion chamber 1a, the amount of evaporated fuel attached to the wall surface of the intake port 8 is obtained, and the amount of evaporated fuel is calculated from the required amount of fuel injection. It is necessary to inject the subtracted fuel injection amount into the intake port 8, that is, to correct the fuel injection amount.

Here, the amount of attached fuel adhering to the wall surface of the intake port 8 and the amount of evaporated fuel from which the attached fuel evaporates can be calculated from the fuel behavior model. If the adhesion rate of the fuel to the wall surface of the intake port 8 is R, the evaporation rate of the fuel that evaporates between the adhering fuels until the next fuel injection is P, and the injection amount of the fuel to the intake port 8 is fi. When the fuel injection amount in the k-th cycle is fi _k , the attached fuel amount fw _{k + 1} in the k + 1 cycle and the evaporated fuel amount fv _{k + 2} in the k + 2 cycle can be expressed as the following equations (1) and (2). .
[Attached fuel amount in the (k + 1) th cycle]
fw _{k + 1} = (1-P) · fw _k + R · fi _k (1)
[Evaporated fuel amount in the k + 2 cycle]
fv _{k + 2} = P · fw _{k + 1} (2)
By using the relationship of the above formulas (1) and (2), it is possible to calculate the adhered fuel amount fw _{k + 1} of the (k + 1) th cycle from the fuel injection amount fi _k of the kth cycle, and further, the adhered fuel amount of the (k + 1) th cycle. The fuel vapor amount fv _{k + 2} in the (k + 2) th cycle can be calculated from fw _{k + 1} . That is, if the adhesion rate R and the evaporation rate P of the ethanol fuel injected into the intake port 8 of the engine 1 can be obtained, the evaporated fuel amount can be calculated, so that the next time based on the calculated evaporated fuel amount. The fuel injection amount can be corrected.

  Here, the fuel adhesion rate R and the evaporation rate P vary according to the operating state of the engine 1. That is, the amount of fuel adhering to the wall surface of the intake port 8 by the ethanol fuel injected by the injector 300 and the amount of evaporated fuel evaporating the ethanol fuel adhering to the wall surface are determined by the load and speed of the engine 1 and the opening / closing of the intake valve 12. It changes appropriately according to the timing, the wall surface temperature of the intake port 8, and the like. Therefore, a rule for specifying each of the adhesion rate R and the evaporation rate P in relation to the engine load Kl, the engine speed Ne, the valve timing VT, and the engine coolant temperature (wall surface temperature of the intake port 8) Tw in advance. By preparing and making the ECU 100 set the adhesion rate R and the evaporation rate P according to the rules, the more accurate adhesion rate R and the evaporation rate P can be set according to the operating state of the engine 1.

  In this case, the fuel injected into the intake port 8 is more easily vaporized as its temperature is higher, so the adhesion rate R becomes a smaller value. Further, the fuel injected into the intake port 8 is more easily taken into the combustion chamber 1a as the intake pipe pressure of the engine 1 is higher, so the adhesion rate R becomes a smaller value. As described above, the fuel adhesion rate R changes significantly according to the fuel temperature and the intake pipe pressure. Therefore, after calculating the adhesion rate R, the fuel adhesion rate R is corrected based on the fuel temperature and the intake pipe pressure. An accurate adhesion rate R can be calculated.

  Subsequently, the operation of the engine 1 will be described along the control flow of the ECU 100. FIG. 4 is a flowchart showing an example of processing of the ECU 100. The engine 1 of this embodiment includes fuel injection means, attached fuel amount calculation means, evaporated fuel amount calculation means, evaporated fuel amount correction means, and fuel injection amount correction means, so that the alcohol fuel injected into the intake port adheres. The fuel vapor amount can be calculated from the fuel amount. Then, by correcting the calculated amount of evaporated fuel based on the engine coolant temperature, when the intake port temperature is near the boiling point of alcohol, the calculation of the amount of evaporated fuel using the evaporation characteristics of the alcohol fuel can be accurately executed. Can do. Furthermore, the fuel injection amount of the internal combustion engine when using 100% alcohol fuel can be optimally controlled by correcting the fuel injection amount based on the obtained correction value of the evaporated fuel amount.

  The control of the ECU 100 starts when an engine start request is made, that is, when the ignition switch is turned on. First, in step S1, the ECU 100 detects the engine speed Ne, the load factor K1, the valve timing VT, and the engine cooling water temperature Tw of the engine 1, and is recorded in advance in the ECU 100 based on these detection results. Referring to the map, the fuel adhesion rate R and the evaporation rate P to the intake port 8 are calculated. In this case, the calculated adhesion rate R may be corrected based on the fuel temperature and the intake pipe pressure. After completing the process of step S1, ECU 100 proceeds to the next step S2.

  In step S2, the ECU 100 calculates a required fuel injection amount Q0 necessary for driving the vehicle from a map determined by the vehicle engine speed Ne and the load factor Kl. After finishing the process of step S2, ECU 100 proceeds to step S3.

  In step S3, the ECU 100 determines whether or not the detected engine coolant temperature Tw is within a range from Tw0-α to Tw0. Here, Tw0 can be set to the boiling point (78.32 ° C.) of the ethanol fuel, and Tw0-α can be set to a temperature (78.32-α ° C.) at which the ethanol fuel starts to evaporate. If the engine coolant temperature Tw is in the range of Tw0-α to Tw0 (step S3 / YES), the ECU 100 determines that the fuel adhering to the wall surface of the intake port 8 has evaporated, and proceeds to step S5. If engine coolant temperature Tw is not within the range of Tw0-α to Tw0 (step S3 / NO), ECU 100 determines that the fuel adhering to the wall surface of intake port 8 has not evaporated, and proceeds to the next step S4.

  If the determination result in step S3 is NO, the ECU 100 proceeds to step S4. In step S4, the ECU 100 determines that the fuel injection amount correction amount QADJ for the next intake port 8 is zero, that is, the fuel injection amount is not corrected. After completing the process of step S4, ECU 100 proceeds to step S6.

If the determination in step S3 is yes, the ECU 100 proceeds to step S5. In step S5, the ECU 100 multiplies the fuel injection amount (fi _k ) injected by the injector 300 last time by the adhesion rate R calculated in step S1 based on the equations (1) and (2) of the fuel behavior model described above. And the amount of fuel adhering to the previous intake port (fw _k ) multiplied by the residual adhering fuel rate (1-P) obtained from the evaporation rate P calculated in step S1 is added to the intake port 8 The amount of fuel adhering to (fw _{k + 1} ) is calculated. Further, the ECU 100 calculates the evaporated fuel amount (fv _{k + 2} ) by multiplying the calculated amount of fuel adhering to the intake port 8 (fw _{k + 1} ) by the evaporation rate P calculated in step S1. Then, the ECU 100 applies the calculated evaporated fuel amount (fv _{k + 2} ) as the correction amount QADJ of the fuel injection amount to the next intake port 8. When the processing of step S5 is completed, ECU 100 proceeds to next step S6.

  In step S6, the ECU 100 obtains a difference Q0-QADJ between the required fuel injection amount Q0 calculated in step S2 and the fuel injection amount correction amount QADJ calculated in step S5, thereby obtaining the next fuel to the intake port 8. The injection amount Q is calculated. FIG. 5 is an explanatory view showing an example of fuel injection control executed by the ECU 100. As the engine 1 that has started is warmed up, the temperature of the intake port 8 also gradually increases. In this case, the ethanol fuel adhering to the wall surface of the intake port 8 has a temperature of the wall surface of the intake port 8 that is lower than the evaporation start temperature of ethanol fuel (less than 78.32-α ° C.) or the temperature of the wall surface of the intake port 8 is ethanol. When the boiling point of the fuel (78.32 ° C.) is exceeded, there is no ethanol fuel that evaporates in the intake port 8. Therefore, the amount of fuel injected into the intake port 8 is the required fuel injection amount Q0 required for driving the vehicle (FIG. 5 (a)). On the other hand, when the temperature of the wall surface of the intake port 8 is near the boiling point of ethanol fuel (78.32-α ° C.), the ethanol fuel adhering to the wall surface of the intake port 8 starts to gradually evaporate, and the temperature of the wall surface of the intake port 8 When the boiling point of the fuel is reached, all the fuel adhering to the wall surface of the intake port 8 evaporates all at once. Therefore, during the period from the evaporation start temperature of the ethanol fuel to the boiling point at which the evaporation is completed, in addition to the fuel injected from the injector 300, the fuel evaporated from the wall surface of the intake port 8 is also sucked into the combustion chamber 1a (FIG. 5 ( b)). Therefore, the amount of evaporated fuel from the wall surface of the intake port 8 is set as the fuel injection amount correction amount QADJ, and the value obtained by subtracting the correction amount QADJ from the required fuel injection amount Q0 is set as the fuel injection amount Q to the next intake port 8. Thus, the amount of ethanol fuel sucked into the combustion chamber 1a can be controlled to the amount of fuel required for driving the vehicle (FIG. 5 (c)). When the processing of step S6 is completed, ECU 100 proceeds to next step S7.

  The ECU 100 determines whether or not there is an ignition OFF request in step S7. If there is no ignition OFF request (step S7 / NO), the ECU 100 returns to step S1 and repeats the above processing. When there is a request for ignition OFF (step S7 / YES), the ECU 100 ends the control process.

  As described above, the engine 1 according to the first embodiment calculates the amount of evaporated fuel of ethanol fuel adhering to the intake port 8 based on the operating state of the internal combustion engine, and the calculated amount of evaporated fuel is based on the engine coolant temperature. Thus, when the wall surface temperature of the intake port 8 is near the boiling point of ethanol, the calculation of the evaporated fuel amount using the evaporation characteristic of the ethanol fuel can be accurately executed. Further, by correcting the next fuel injection amount based on the calculated evaporated fuel amount, the fuel injection amount of the internal combustion engine when using 100% alcohol fuel can be optimally controlled. Thus, by optimally controlling the fuel injection amount during the transient operation, the fuel consumption and exhaust emission of the vehicle can be improved, and the startability of the internal combustion engine can be improved.

  Further, the engine 1 of the first embodiment can also correct the adhesion rate R calculated from the operating state of the internal combustion engine based on the fuel temperature and the intake pipe pressure. Since the fuel adhesion rate R changes significantly according to the fuel temperature and the intake pipe pressure, after calculating the adhesion rate R, the fuel adhesion rate R is corrected based on the fuel temperature and the intake pipe pressure. R can be calculated.

In the engine 1 of the first embodiment, the amount of fuel adhering to the intake port 8 (fw _{k + 1} ) is determined based on the equation (1) of the fuel behavior model, and the fuel injection amount (fi _k ) injected by the injector 300 last time. Multiplied by the adhesion rate R calculated from the operating state of the internal combustion engine, and the amount of fuel adhering to the previous intake port (fw _k ) and the residual adhesion determined from the evaporation rate P calculated from the operating state of the internal combustion engine It can be calculated by adding the product of the fuel rate (1-P).

Further, in the engine 1 of the first embodiment, of the ethanol fuel adhering to the intake port 8, the amount of evaporated fuel (fv _{k + 2} ) evaporated until the next fuel injection is expressed by the equation (2) of the fuel behavior model. Based on the calculated fuel amount adhering to the intake port 8 (fw _{k + 1} ), the evaporation rate P calculated from the operating state of the internal combustion engine can be multiplied.

  Further, the engine 1 of the first embodiment determines the fuel injection amount when the detection result of the engine cooling water temperature Tw is between the ethanol fuel evaporation start temperature 78.32-α ° C. and the boiling point 78.32 ° C. It can correct | amend with the cooling water temperature Tw. The ethanol fuel adhering in the intake port 8 evaporates when the wall surface temperature of the intake port 8 is between the evaporation start temperature (78.32-α ° C) and the boiling point (78.32 ° C) of the ethanol fuel. Therefore, the fuel injection control of the internal combustion engine when using ethanol fuel can be executed with higher accuracy by setting the amount of evaporated fuel during this period as the correction amount for the next fuel injection amount. Exhaust emission can be further improved, and startability of the internal combustion engine can be improved.

  The engine 1 according to the first embodiment can detect the engine coolant temperature Tw near the intake port 8. In this embodiment, the wall surface temperature of the intake port 8 is detected by detecting the engine coolant temperature Tw. However, the wall surface temperature of the intake port 8 can be detected more accurately by making the Tw detection location near the intake port 8. Can be detected. Therefore, the fuel injection control of the internal combustion engine when using ethanol fuel can be executed with higher accuracy, so that the fuel efficiency and exhaust emission of the vehicle can be further improved and the startability of the internal combustion engine is improved. Can be made.

  Next, a second embodiment of the present invention will be described. The engine 50 of the present embodiment has substantially the same configuration as the engine 1 of the first embodiment, but the engine 50 calculates the amount of fuel that adheres to the intake valve out of the injected fuel. A calculating means; an intake valve evaporating fuel amount calculating means for calculating an evaporated fuel amount that evaporates until the next fuel injection among the fuel adhering to the intake valve; an intake valve wall surface temperature detecting means for detecting a wall surface temperature of the intake valve; The engine 1 is different from the engine 1 in that it includes an intake valve evaporated fuel amount correcting means for correcting the evaporated fuel amount from the intake valve based on the detection result of the intake valve wall surface temperature detecting means.

  FIG. 6 is an explanatory diagram showing a schematic configuration of an engine 50 incorporating the fuel injection control device of the present invention. FIG. 6 shows only the configuration of one cylinder of the engine. The engine 50 according to the present embodiment includes an ECU 100 inside the vehicle as in the first embodiment. The ECU 100 corresponds to an intake valve attached fuel amount calculating means, an intake valve evaporated fuel amount calculating means, and an intake valve evaporated fuel amount correcting means. Further, the engine 50 includes an intake valve wall temperature sensor 500 in the vicinity of the intake valve 12. As the intake valve wall temperature sensor 500, a non-contact type sensor that detects the wall surface temperature Tv of the intake valve 12 using infrared rays or the like can be used. The intake valve wall temperature sensor 500 corresponds to intake valve wall surface temperature detecting means for detecting the wall surface temperature of the intake valve. When the engine 1 is started, as the engine temperature rises due to warm-up, the temperature in the intake port 8 also rises. Here, since the temperature of the intake valve 12 usually rises faster than the wall surface of the intake port 8, the fuel attached to the intake valve 12 evaporates faster than the ethanol fuel attached to the intake port 8. Therefore, by detecting the temperature of the intake valve 12 by the intake valve wall temperature sensor 500 and correcting the fuel injection amount based on the detection result, the evaporated fuel amount of the attached fuel in the intake port 8 and the evaporation are more accurately detected. Timing can be calculated.

  Subsequently, the operation of the engine 50 will be described along the control flow of the ECU 100. FIG. 7 is a flowchart illustrating an example of processing of the ECU 100. In addition, about the process similar to Example 1, the same reference number is attached | subjected in drawing and the detailed description is abbreviate | omitted. Similar to the first embodiment, the control of the ECU 100 starts when an engine start request is made, that is, when the ignition switch is turned on.

  First, in step S8, the ECU 100 detects the engine speed Ne of the engine 50, the load factor Kl, the valve timing VT, the engine coolant temperature Tw, and the intake valve wall temperature Tv, and based on these detection results. Then, referring to a map recorded in the ECU 100 in advance, the fuel adhesion rate R and the evaporation rate P to the intake port 8 and the adhesion rate Rv and the evaporation rate Pv to the intake valve 12 are calculated. In this case, the calculated adhesion rates R and Rv may be corrected based on the fuel temperature and the intake pipe pressure. After finishing the process of step S8, the ECU 100 proceeds to the next step S9.

  In step S9, the ECU 100 calculates a required fuel injection amount Q0 required for driving the vehicle from a map determined by the vehicle engine speed Ne and the load factor Kl. After completing the process of step S9, ECU 100 proceeds to step S10.

  In step S10, the ECU 100 determines whether or not the detected engine coolant temperature Tw is within a range from Tw0-α to Tw0. Here, Tw0 can be set to the boiling point (78.32 ° C.) of the ethanol fuel, and Tw0-α can be set to a temperature (78.32-α ° C.) at which the ethanol fuel starts to evaporate. If the engine coolant temperature Tw is within the range of Tw0-α to Tw0 (step S10 / YES), the ECU 100 determines that the fuel adhering to the wall surface of the intake port 8 has evaporated, and proceeds to step S12. If the engine coolant temperature Tw is not within the range of Tw0-α to Tw0 (step S10 / NO), the ECU 100 determines that the fuel adhering to the wall surface of the intake port 8 has not evaporated, and proceeds to the next step S11.

  If the determination result in step S10 is NO, the ECU 100 proceeds to step S11. In step S11, the ECU 100 determines that the correction amount QADJw based on the amount of fuel evaporated from the wall surface of the intake port 8 is zero among the correction amount of the fuel injection amount to the intake port 8 next time. When the ECU 100 finishes the process of step S11, it proceeds to step S13.

If the determination in step S10 is yes, the ECU 100 proceeds to step S12. In step S12, the ECU 100 multiplies the fuel injection amount (fi _k ) injected by the injector 300 last time by the adhesion rate R calculated in step S1 based on the equations (1) and (2) of the fuel behavior model described above. And the amount of fuel adhering to the previous intake port (fw _k ) multiplied by the residual adhering fuel rate (1-P) obtained from the evaporation rate P calculated in step S1 is added to the intake port 8 The amount of fuel adhering to (fw _{k + 1} ) is calculated. Further, the ECU 100 calculates the evaporated fuel amount (fv _{k + 2} ) by multiplying the calculated amount of fuel adhering to the intake port 8 (fw _{k + 1} ) by the evaporation rate P calculated in step S1. Then, the ECU 100 applies the calculated evaporated fuel amount (fv _{k + 2} ) as the correction amount QADJw of the fuel injection amount to the next intake port 8. When the processing of step S12 is completed, ECU 100 proceeds to next step S13.

  In step S13, the ECU 100 determines whether or not the detected intake valve wall temperature Tv is within a range from Tv0-α to Tv0. Here, Tv0 can be set to the boiling point (78.32 ° C.) of the ethanol fuel, and Tv0-α can be set to a temperature (78.32-α ° C.) at which the ethanol fuel starts to evaporate. When the intake valve wall temperature Tv is within the range of Tv0-α to Tv0 (step S13 / YES), the ECU 100 determines that the fuel adhering to the wall surface of the intake valve 12 has evaporated, and proceeds to step S15. When the intake valve wall temperature Tv is not within the range of Tv0-α to Tv0 (step S13 / NO), the ECU 100 determines that the fuel adhering to the wall surface of the intake valve 12 has not evaporated, and proceeds to the next step S14. .

  If the determination result in step S13 is NO, the ECU 100 proceeds to step S14. In step S11, the ECU 100 determines that the correction amount QADJv based on the amount of fuel evaporated from the wall surface of the intake valve 12 is zero among the correction amount of the fuel injection amount to the intake port 8 next time. After completing the process of step S11, ECU 100 proceeds to step S16.

If the determination in step S13 is yes, the ECU 100 proceeds to step S15. In step S15, the ECU 100 multiplies the fuel injection amount (fi _k ) injected by the injector 300 last time by the adhesion rate Rv calculated in step S1 based on the equations (1) and (2) of the fuel behavior model described above. And the amount of fuel adhering to the previous intake valve (fwv _k ) multiplied by the residual adhering fuel rate (1-Pv) obtained from the evaporation rate Pv calculated in step S8, is added to the intake valve 12 The amount of fuel adhering to (fwv _{k + 1} ) is calculated. Further, the ECU 100 calculates the evaporated fuel amount (fvv _{k + 2} ) by multiplying the calculated amount of fuel adhering to the intake valve 12 (fwv _{k + 1} ) by the evaporation rate Pv calculated in step S8. Then, the ECU 100 applies the calculated evaporated fuel amount (fvv _{k + 2} ) as the correction amount QADJv of the fuel injection amount to the next intake port 8. After finishing the process of step S15, the ECU 100 proceeds to the next step S16.

  In step S16, the ECU 100 obtains a difference Q0−QADJw−QADJv between the required fuel injection amount Q0 calculated in step S9 and the fuel injection amount correction amounts QADJw and QADJv calculated in steps S12 and S15. The fuel injection amount Q to the intake port 8 is calculated. FIG. 8 is an explanatory view showing an example of fuel injection control executed by the ECU 100. As the engine 50 that has started is warmed up, the temperatures of the intake port 8 and the intake valve 12 gradually increase. In this case, the ethanol fuel adhering to the wall surfaces of the intake port 8 and the intake valve 12 is when the temperature of the intake port 8 wall surface and the intake valve 12 wall surface is less than the evaporation start temperature of ethanol fuel (less than 78.32-α ° C.) Alternatively, when the temperature of the wall surface of the intake port 8 and the wall surface of the intake valve 12 exceeds the boiling point of ethanol fuel (78.32 ° C.), there is no ethanol fuel that evaporates in the intake port 8. Therefore, the amount of fuel injected into the intake port 8 is the required fuel injection amount Q0 required for driving the vehicle (FIG. 8 (a)). On the other hand, when the temperature of the wall surface of the intake port 8 is near the boiling point of ethanol fuel (78.32-α ° C.), the ethanol fuel adhering to the wall surface of the intake port 8 starts to gradually evaporate, and the temperature of the wall surface of the intake port 8 When the boiling point of the fuel is reached, all the fuel adhering to the wall surface of the intake port 8 evaporates all at once. Therefore, during the period from the evaporation start temperature of the ethanol fuel to the boiling point at which the evaporation is completed, in addition to the injected fuel from the injector 300, the fuel evaporated from the wall surface of the intake port 8 is also sucked into the combustion chamber 1a (FIG. 8 ( b)). Similarly, while the temperature of the wall surface of the intake valve 12 is from the evaporation start temperature of the ethanol fuel to the boiling point where the evaporation is completed, the fuel evaporated from the wall surface of the intake valve 12 in addition to the fuel injected from the injector 300 is also in the combustion chamber 1a. Inhaled. In this case, since the temperature of the intake valve 12 usually rises faster than the wall surface of the intake port 8, the fuel attached to the intake valve 12 evaporates at an earlier timing than the ethanol fuel attached to the intake port 8 ( FIG. 8 (c)). Therefore, the amount of evaporated fuel from the wall surface of the intake port 8 and the amount of evaporated fuel from the wall surface of the intake valve 12 are respectively calculated, and values subtracted from the required fuel injection amount Q0 as fuel injection amount correction amounts QADJw and QADJv. By setting the fuel injection amount Q to the intake port 8 next time, the amount of ethanol fuel sucked into the combustion chamber 1a can be controlled to the fuel amount required for driving the vehicle (FIG. 8 (d)). ). After finishing the process of step S16, the ECU 100 proceeds to the next step S17.

  The ECU 100 determines whether or not there is an ignition OFF request in step S17. If there is no ignition OFF request (step S17 / NO), the ECU 100 returns to step S8 and repeats the above processing. If there is a request for turning off the ignition (step S17 / YES), the ECU 100 ends the control process.

  As described above, the engine 50 of the second embodiment calculates the amount of evaporated fuel of ethanol fuel adhering to the wall surface of the intake port 8 and the wall surface of the intake valve 12 based on the operating state of the internal combustion engine, and calculates the calculated evaporation. By correcting the fuel amount based on the engine coolant temperature and the intake valve wall surface temperature, the evaporated fuel using the evaporation characteristics of ethanol fuel when the intake port 8 wall surface temperature and the intake valve 12 wall surface temperature are near the boiling point of ethanol. The amount can be calculated accurately. Further, by correcting the next fuel injection amount based on the calculated evaporated fuel amount, the fuel injection amount of the internal combustion engine when using 100% alcohol fuel can be optimally controlled. Thus, by optimally controlling the fuel injection amount during the transient operation, the fuel consumption and exhaust emission of the vehicle can be improved, and the startability of the internal combustion engine can be improved.

  Note that the engine 50 of the second embodiment can also estimate the wall surface temperature of the intake valve 12 from the operating state of the internal combustion engine without using the intake valve wall temperature sensor 500. The amount of change ΔTv in the wall temperature Tv of the intake valve 12 includes the combustion gas heat reception amount Qb, the contact surface heat reception amount Qs, the fuel vaporization heat amount Qf, the intake gas heat reception amount Qgin generated when the intake valve 12 is opened, and the blowback heat reception amount. It can be represented by Qgback. Therefore, it is possible to accurately calculate the total amount of heat received by the intake valve 12 by separately estimating these parameters based on the operating state of the internal combustion engine and integrating the estimated values. The intake valve 12 wall temperature Tv can also be accurately estimated based on the total amount of heat received thus calculated.

  The above embodiments are merely examples for carrying out the present invention. Therefore, the present invention is not limited to these, and various modifications and changes can be made within the scope of the gist of the present invention described in the claims.

It is explanatory drawing which showed schematic structure of the engine incorporating the fuel-injection control apparatus of Example 1. FIG. It shows the distillation behavior of ethanol and gasoline. 1 is an explanatory diagram illustrating a schematic configuration of one cylinder of an engine according to Embodiment 1. FIG. The flow of the control which ECU of Example 1 performs is shown. An example of fuel injection amount correction performed by the ECU is shown. It is explanatory drawing which showed schematic structure of the engine incorporating the fuel-injection control apparatus of Example 2. FIG. The flow of control which ECU of Example 2 performs is shown. An example of fuel injection amount correction performed by the ECU is shown.

Explanation of symbols

1 Engine 1a Combustion chamber 2 Piston 3 Crankshaft 5 Crank angle sensor 8 Intake port 10 Exhaust port 12 Intake valve 13 Intake camshaft 14 Exhaust valve 15 Exhaust camshaft 16 Electric variable valve mechanism (Electric VVT mechanism)
17 Electric motor 18 Intake cam angle sensor 19 Hydraulic variable valve mechanism (hydraulic VVT mechanism)
20 Oil control valve (OCV)
21 Exhaust cam angle sensor 28 Water temperature sensor (engine cooling water temperature detection means)
100 ECU (attached fuel amount calculating means, evaporated fuel amount calculating means, evaporated fuel amount correcting means, fuel injection amount correcting means)
300 Injector (fuel injection means)
500 Intake valve wall temperature sensor

Claims (7)

A fuel injection control device for an internal combustion engine comprising fuel injection means for injecting a single component alcohol fuel into an intake port,
An adhering fuel amount calculating means for calculating an adhering fuel amount adhering to the intake port among the fuel injected by the fuel injection means;
An evaporative fuel amount calculating means for calculating an evaporative fuel amount that evaporates before the next fuel injection among the fuel adhering to the intake port;
Cooling water temperature detecting means for detecting the cooling water temperature of the internal combustion engine;
An evaporated fuel amount correcting means for correcting the calculation result of the evaporated fuel amount calculating means, based on the detection result of the cooling water temperature detecting means;
A fuel injection amount correction unit that corrects a fuel injection amount of the fuel injection unit based on a calculation result of the attached fuel amount calculation unit and a correction result of the evaporated fuel amount correction unit;
A fuel injection control device comprising: Of the fuel injected by the fuel injection means, an intake valve attached fuel amount calculating means for calculating an attached fuel amount attached to the intake valve;
Among the fuel adhering to the intake valve, an intake valve evaporated fuel amount calculating means for calculating an evaporated fuel amount that evaporates until the next fuel injection;
Intake valve wall surface temperature detecting means for detecting the wall surface temperature of the intake valve of the vehicle;
An intake valve evaporated fuel amount correcting means for correcting the calculation result of the intake valve evaporated fuel amount calculating means based on the detection result of the intake valve wall surface temperature detecting means;
The fuel injection amount correcting means includes a calculation result of the attached fuel amount calculating means, a calculation result of the intake valve attached fuel amount calculating means, a correction result of the evaporated fuel amount correcting means, and an intake valve evaporated fuel amount correction. 2. The fuel injection control apparatus according to claim 1, wherein the fuel injection amount of the fuel injection means is corrected based on a correction result of the means. An adhering fuel rate calculating means for calculating an adhering fuel rate adhering to the intake port among the fuel injected by the fuel injection means;
Evaporative fuel rate calculating means for calculating an evaporative fuel rate that evaporates between the fuel adhering to the intake port until the next fuel injection,
The attached fuel amount calculating means includes a fuel injection amount previously injected by the fuel injection means, a calculation result of the attached fuel rate calculating means, a calculation result previously calculated by the attached fuel amount calculating means, and the evaporated fuel rate. 3. The fuel injection control apparatus according to claim 1, wherein the amount of attached fuel is calculated based on a residual fuel rate obtained from a calculation result of a calculation means. An evaporative fuel rate calculating means for calculating an evaporative fuel rate that evaporates between fuel adhering to the intake port until the next fuel injection;
3. The evaporated fuel amount calculating unit calculates the evaporated fuel amount based on a calculation result of the attached fuel amount calculating unit and a calculation result of the evaporated fuel rate calculating unit. Fuel injection control device.   The fuel injection amount correction means corrects the fuel injection amount of the fuel injection means when the detection result of the cooling water temperature detection means is between the evaporation start temperature and the boiling point of the fuel. Item 5. The fuel injection control device according to any one of Items 1 to 4.   The fuel injection amount correction unit corrects the fuel injection amount of the fuel injection unit when the detection result of the intake valve wall surface temperature detection unit is between the evaporation start temperature and the boiling point of the fuel. The fuel injection control device according to claim 5. The fuel injection control device according to any one of claims 1 to 6, wherein the cooling water temperature detection means is provided in the vicinity of the intake port.

Images