JP2013133791A - Control device of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To properly estimate a fuel concentration even if an engine is stopped in the middle of fuel switching after refueling and diffusion progresses during the stop, when estimating the fuel concentration at the position of a fuel injection valve in consideration of fuel movement in a fuel passage.SOLUTION: When the fuel is being switched (S204), it is determined whether a difference between a start time alcohol concentration ekalc at the position of a fuel property sensor and a concentration learning value EG at previous stop is larger than a predetermined reference value or not (S208). When the difference is larger than the reference value, a correction factor kis calculated (S210) based on a difference between a concentration at engine stop of a previous trip and a concentration at engine start of the present trip, a concentration distribution in the fuel passage at the engine stop of the previous trip and an elapsed time (soak time) from the engine stop to the start. When the difference is equal to or below the reference value, the correction factor kis set at 1 (S122). The correction factor kis used to correct a concentration estimate of fuel at the position of the fuel injection valve.

Description

  The present invention relates to a control device for an internal combustion engine, and more particularly to an apparatus having a function of estimating a fuel concentration immediately before being injected.

  For example, in the system disclosed in Patent Document 1, the fuel concentration immediately before being injected from the fuel injection valve is estimated by a model that takes into account the movement of the fuel from the fuel tank until it reaches the fuel injection valve, and the fuel accordingly The injection amount is controlled. This system has a cell for storing the fuel concentration in each region corresponding to the region obtained by equally dividing the volume of the fuel passage from the detection position of the fuel property sensor to the position where the injector is attached. When the volume of fuel for one region is consumed, the fuel concentration of each cell is shifted by one downstream, and the cells in the region corresponding to the detection position of the fuel property sensor are detected based on the fuel property sensor. The measured fuel concentration is stored. In the system of Patent Document 1, the movement of the fuel concentration is traced by shifting the cell data corresponding to each region in this way, and the value of the fuel concentration stored in the most downstream cell is controlled by the air-fuel ratio control. Used for.

  The system of Patent Document 1 further considers fuel mixing between regions during circulation in the fuel passage, calculates a diffusion coefficient for reflecting this based on the fuel flow rate, and uses the calculated diffusion coefficient. The fuel concentration is estimated. The diffusion coefficient is set to be larger as the fuel flow rate is smaller. Thereby, the difference between the fuel concentration at the detection position of the fuel property sensor and the fuel concentration of the fuel injected from the fuel injection valve is suppressed, and air-fuel ratio control can be performed more reliably.

JP 2011-111916 A

  However, in this configuration, when a plurality of types of fuel having different alcohol concentrations are supplied and the engine is stopped in the middle of the alcohol concentration change after refueling, when the engine is started next time, the diffusion proceeds while the engine is stopped. Therefore, the estimation using the information at the stop point deviates from the actual concentration. Therefore, in such a case, the apparatus of Patent Document 1 cannot properly control, and there is room for deterioration of drivability such as a start failure.

  The present invention aims to solve the problems of the prior art, and diffusion proceeds while the engine is stopped in estimating the fuel concentration at the fuel supply position in consideration of the movement of fuel in the fuel passage. Even in such a case, an improved control device for an internal combustion engine is provided so that estimation of fuel concentration can be appropriately executed.

In order to achieve the above object, the first invention provides
Storage means having a plurality of storage cells associated with each of a plurality of passage regions formed by dividing the volume of the fuel passage between the fuel property sensor installed in the fuel passage of the internal combustion engine and the fuel injection valve;
The fuel concentration data according to the output of the fuel property sensor is recorded in the memory cell corresponding to the region closest to the fuel property sensor, and the fuel concentration data stored in each of the memory cells according to the fuel consumption amount is recorded. Each data is shifted to the storage cell corresponding to the previous area in the fuel flow direction, and the fuel injection valve injects the fuel according to the fuel concentration data stored in the storage means and the fuel diffusion coefficient. Concentration estimating means for estimating the fuel concentration immediately before being performed;
An injection amount control means for controlling the fuel injection amount from the fuel injection valve in accordance with the fuel concentration estimated by the concentration estimation means;
An internal combustion engine control device comprising:
And a correction means for correcting the estimated fuel concentration based on the output of the fuel property sensor when the internal combustion engine is stopped and restarted. It is what.

  In the first aspect of the present invention, when the internal combustion engine is stopped and restarted, the correcting means corrects the estimated fuel concentration based on the output of the fuel property sensor at the time of stopping and restarting. Even when the diffusion proceeds while the engine is stopped, the fuel concentration can be estimated appropriately.

The second aspect of the present invention
The internal combustion engine has an in-cylinder injection valve that injects fuel into the combustion chamber, and a port injection valve that injects fuel into the intake port,
The apparatus further comprises selection means for selecting fuel supply from the in-cylinder injection valve when the calculation by the correction means is after the closing timing of the intake valve.

  In the second aspect of the present invention, the internal combustion engine has an in-cylinder injection valve and a port injection valve, and when the selection means finishes the calculation by the correction means after the closing timing of the intake valve, Select fuel supply. Therefore, it is possible to appropriately estimate the fuel concentration while ensuring the calculation time by the correcting means.

The third aspect of the present invention provides
The selection means selects the fuel supply from the port injection valve from the end of the calculation until the closing timing of the intake valve when the end of the calculation by the correction means is before the closing timing of the intake valve, and from the closing timing of the intake valve The fuel supply from the cylinder injection valve is selected later.

  In the third aspect of the present invention, when the end of the calculation by the correcting means is before the closing timing of the intake valve, the selecting means selects the fuel supply from the port injection valve from the end of the calculation to the closing timing of the intake valve, After the closing timing of the valve, the fuel supply from the cylinder injection valve is selected. Therefore, even when a fuel with a high alcohol concentration is used, port injection excellent in low temperature startability can be utilized to the maximum extent.

It is a schematic diagram for demonstrating the structure of the system in Embodiment 1 of this invention. It is a figure for demonstrating the control in Embodiment 1 of this invention. It is a figure for demonstrating the relationship between the expansion coefficient used in Embodiment 1 of this invention, and a fuel flow volume. It is a figure which shows an example of the relationship between the distance from the position of a fuel property sensor, and density | concentration when there exists density | concentration diffusion. It is a figure which shows an example of the fuel concentration of each part of a fuel channel at the time of an engine stop and a restart. It is a flowchart for demonstrating the routine of control which a control apparatus performs in Embodiment 1 of this invention. It is a flowchart which shows the part which concerns on calculation of a correction coefficient among the control which a control apparatus performs in Embodiment 1 of this invention. It is a schematic diagram for demonstrating the structure of the system in Embodiment 2 of this invention. It is a flowchart for demonstrating the routine of control which a control apparatus performs in Embodiment 2 of this invention. It is a timing diagram which shows the state of various signals during execution of control of the implementation mobile 2 of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and the description thereof is simplified or omitted.

<Embodiment 1>
FIG. 1 shows the configuration of the entire system including peripheral devices in Embodiment 1 of the present invention. The system of FIG. 1 is applied to an internal combustion engine that can be operated with a gasoline / alcohol mixed fuel. The system of FIG. 1 includes a port injection valve 2 for supplying fuel to each cylinder of an internal combustion engine, and a fuel tank 4 for storing fuel. The port injection valve 2 can inject fuel into an unillustrated intake port. The port injection valve 2 and the fuel tank 4 are connected by a fuel passage 6. A fuel pump 8 is installed in the fuel passage 6 so that the fuel in the fuel tank 4 can be delivered to the port injector 2 at a predetermined flow rate. A fuel flow rate sensor 10 that generates an output corresponding to the fuel flow rate is installed downstream of the fuel pump 8. A fuel property sensor 12 that generates an output corresponding to the fuel concentration is installed downstream of the fuel pump 8 in the fuel passage 6.

  This system includes a control device 14. The control device 14 is electrically connected to the fuel property sensor 12 and receives the output of the fuel property sensor 12 to detect the fuel concentration. The control device 14 is electrically connected to the fuel pump 8 and the port injection valve 2. The control device 14 issues a control signal to the fuel pump 8 and the port injection valve 2, thereby controlling the fuel flow rate and the fuel injection amount from the port injection valve 2.

  This system assumes a region where the volume V1 of the fuel passage from the fuel property sensor 12 of the fuel passage 6 to the port 2 before the port injection valve is divided into n-1 and divided so as to intersect the fuel flow direction. . The control device 14 corresponds to each of a total of n + 1 regions including these regions, a region where the fuel property sensor 12 is installed (inlet region), and a region where the port injector 2 is installed (exit region). Thus, a cell (memory cell) is provided. Each cell stores the fuel concentration in the corresponding region (fuel concentration data) and the detection time at which the fuel concentration was detected. In the following embodiments, each cell is numbered in order from the front of the fuel flow direction of the fuel passage 6 so that the cell corresponding to the inlet region is 0th and the cell corresponding to the outlet region is nth. It is assumed that

FIG. 2 is a diagram for explaining a method of storing fuel concentration and detection time data in cells in a corresponding region in the first embodiment of the present invention. FIG. 2 (a) shows the fuel concentration E _s (i) stored in each cell i at a certain point in time, and FIG. 2 (b) shows that the volume (V1 / ( The concentration E _{s + 1} (i) to be rewritten in each cell i is shown at the time point s + 1 when the fuel of n-1)) is consumed. Hereinafter, in the detailed description of the invention, the volume (V1 / (n-1)) of one region is referred to as "unit volume".

Specifically, as shown in FIG. 2 (a), after the concentration E _s (i) is recorded in each cell at a certain time s, when the fuel moves again by the unit volume, the time shown in FIG. 2 (b). At s + 1, the fuel concentration recorded in each cell and its detection time are shifted to a cell corresponding to one downstream area. That is, the concentration E _{s + 1} (i) of the i-th cell at the time point s + 1 is equal to the fuel concentration E _s (i-1) recorded in the previous i-1th cell at the time point s. Become. Similarly, the detection time is stored at time s + 1 to i-th cell T _{s + 1} (i), the time T _s which has been recorded in the immediately preceding the i-1 th cell at a previous point in time s (i-1).

Further, the output of the fuel property sensor 12 is periodically read, and the fuel concentration is repeatedly detected. The average value of the detected concentration is stored as the concentration of the fuel in the region where the fuel property sensor 12 is installed at the time of the data shift described above. That is, at the time point s + 1 at which the above data is shifted, the fuel concentration is recorded as the fuel concentration E _{s + 1} (0) in the 0th cell corresponding to the region where the fuel property sensor 12 is installed.

In the first embodiment, when the data shift, that is, when the fuel moves by the unit volume, the fuel concentration E _{s + 1} (i) stored in the i-th cell corresponding to the outlet region is the fuel diffusion coefficient k. ₁ , where k ₂ is a correction coefficient related to diffusion while the engine is stopped, the calculation is performed according to the following equation (1).

  The data of each cell is shifted when the fuel of the unit volume moves, but it does not matter at which point it is shifted. , S + 1 is not described, and only the cell number i is displayed and is expressed as fuel concentration E (i) and concentration detection time T (i).

  Here, in the above formula (1), the fuel concentration stored in the (n−1) th cell is estimated to be a value detected when the n−1th fuel passes through the fuel property sensor 12. That is, the movement of the fuel passage 6 of the fuel was tracked by sequentially shifting the cell data until the fuel moved from the region where the fuel property sensor 12 was installed to the region immediately before the port injector 2. It is a value.

However, since the fuel is mixed with the surrounding fuel by concentration diffusion while passing through the fuel passage 6, it is considered that the actual fuel concentration deviates from the fuel concentration stored in the cell. Therefore, in the first embodiment, the fuel concentration is calculated with a delay in the concentration change by applying the diffusion coefficient k ₁ as in the above equation (1) in consideration of the concentration diffusion of the fuel.

The diffusion coefficient k ₁ in the above equation (1) is set in relation to the fuel flow rate. FIG. 3 is a diagram for explaining the relationship between the diffusion coefficient k ₁ and the fuel flow rate used in Embodiment 1 of the present invention. In FIG. 3, the horizontal axis represents the average fuel flow [l / h], and the vertical axis represents the diffusion coefficient k ₁ . The diffusion coefficient is a positive value and is generally set between 0 and 25. As shown in FIG. 3, since the diffusion of the fuel decreases as the fuel flow rate increases, the diffusion coefficient k ₁ is also set to a small value. Further, since the concentration diffusion of the fuel increases when the fuel flow rate is extremely small, the diffusion coefficient k ₁ is also set to a large value. Since the diffusion coefficient k ₁ is a percentage ratio, it is divided by 100 in equation (1).

  Since the relationship between the fuel flow rate and the concentration diffusion differs depending on the diameter, length, etc. of the fuel passage, the relationship between the fuel flow rate and the diffusion coefficient is obtained by experiments in advance for each system, Are stored as a map that relates to each other.

On the other hand, a plurality of types of fuels having different alcohol concentrations are refueled, and the engine is operated in the middle of the alcohol concentration switching after refueling (that is, until all the fuel before refueling is injected and no longer exists in the fuel passage 6). When the engine is stopped, when the engine is started next time, the diffusion proceeds while the engine is stopped. Therefore, the estimation using the information at the time of stopping deviates from the actual concentration. In such a case, control cannot be performed properly, and drivability deterioration such as start-up failure may occur. Therefore, in the first embodiment, the estimated fuel concentration is corrected by multiplying the correction coefficient k ₂ in consideration of the fuel concentration diffusion while the engine is stopped.

  In this embodiment, fuel diffusion in the liquid layer in the fuel passage 6 becomes a target phenomenon, so it is considered appropriate to apply Fick's diffusion law. Fick's diffusion law is expressed by the following equation (2).

  Here, D is a diffusion coefficient, which is a physical property value specific to alcohol indicating the rate at which alcohol diffuses in gasoline. x is a position, which is a distance from the position of the fuel property sensor 12 to the position of the port injection valve 2 and depends on the design of the fuel system. J is a diffusion bundle, which is the amount of solute that diffuses per unit time. The diffusion flux J is a change in alcohol concentration at the position of the fuel property sensor 12 (concentration difference between when the engine of the previous trip is stopped and when the engine of the current trip is started), concentration distribution in the fuel passage 6 when the engine of the previous trip is Also, there is a correlation with the elapsed time from the engine stop to the start (that is, the soak time), and mapping is performed in advance by a test. In general, the above formula (2) is, for example, that the alcohol concentration at the position of the fuel property sensor 12 is high and the fuel is switched at the position of the fuel property sensor 12, and the alcohol concentration increases from the downstream side to the port injection valve 2. When the soak time elapses from a stepwise low state and the diffusion proceeds, as shown in FIG. 4, the curve is such that the concentration continuously attenuates as the distance from the position of the fuel property sensor 12 increases. .

On the other hand, as shown in FIG. 5, the fuel concentration when the engine is stopped and started next time during the changeover of the fuel is the concentration distribution in the fuel passage 6 when the engine is stopped on the previous trip, and the fuel property sensor 12. It changes continuously as it goes downstream from the position. Therefore, in this embodiment, the concentration difference between the engine stop of the previous trip and the engine start of the current trip, the concentration distribution in the fuel passage 6 when the engine of the previous trip is stopped, and the elapsed time from the engine stop to the start (that is, Alcohol at the position of the port injector 2 by calculating the diffusion flux J of each cell by a predetermined function and integrating the above equation (2) at the position x over the entire length of the fuel passage 6 based on the soak time). A correction coefficient k ₂ for estimating the density can be calculated. In this embodiment, when the internal combustion engine is stopped and restarted, the estimated fuel concentration is corrected based on the output of the fuel property sensor at the time of stopping and at the time of restarting, so that the diffusion progressed while the engine was stopped. Even in this case, the estimation can be appropriately performed.

  FIG. 6 is a flowchart for explaining a control routine executed by the control device 14 in the first embodiment of the present invention. In the routine of FIG. 6, the integrated fuel movement amount Q1 is calculated (S102). The integrated fuel movement amount Q1 is obtained from the fuel flow rate q1 [l / h] detected according to the output of the fuel flow rate sensor 10.

  Next, the fuel concentration x is detected (S104). The fuel concentration x is detected based on the output of the fuel property sensor 12. Next, the integrated density value X1 is calculated (S106). The concentration integrated value X1 is obtained by adding the fuel concentration x detected in step S104 to the currently stored concentration integrated value X1 each time this routine is executed. The accumulated concentration value X1 is an accumulation of the fuel concentration x detected each time this routine is executed until the fuel moves by the unit volume. This value is used to calculate the average concentration of the fuel.

  Next, 1 is added to the integration number counter c1 (S108). The cumulative number counter c1 is set to zero as an initial value, and stores the number of routines executed until the fuel for the unit volume passes.

  Next, it is determined whether or not the integrated fuel movement amount Q1 is equal to or greater than the unit volume of fuel (V1 / (n-1)) (S110). Here, if the cumulative fuel movement amount Q1 ≧ unit volume (V1 / (n-1)) is not established, the fuel injection amount is calculated based on the fuel concentration Es (n) in the outlet region at the currently recorded time point s. Control is executed (S112).

  On the other hand, if it is confirmed in step S110 that the accumulated fuel movement amount Q1 ≧ unit volume (V1 / (n−1)), then the average flow rate S1 is calculated (S114). The average flow rate S1 is calculated according to the following equation (3).

Average flow rate S1 = Volume V1 / {t-T (n-1)} (3)
In formula (3), T (n-1) is the current concentration, and the fuel concentration stored in the n-1st cell, that is, the cell corresponding to the area immediately before the exit area is detected. Time, and t represents the current time. That is, by dividing the volume V1 by the elapsed time from the detection of the fuel concentration in the region immediately before the outlet region to the current time t, the fuel in the region immediately before the outlet region is transferred from the fuel property sensor 12 to the port injector. 2 The average flow rate S1 up to the region immediately before is calculated.

Next, the diffusion coefficient k ₁ is calculated (S116). As described above, the diffusion coefficient k ₁ is a value determined according to the average flow rate S 1 calculated in step S 114, and is calculated according to the map stored in the control device 14.

Next, the fuel concentration E (n) stored in the nth cell corresponding to the exit area, the fuel concentration E (n-1) of the cell immediately before it, and the diffusion coefficient obtained in step S116 According to k1, the fuel concentration is calculated by the above equation (1). This value is stored as the fuel concentration E (n) of the nth cell (S118). Equation (1) includes a correction coefficient k ₂ , and this correction coefficient k ₂ is set to a different value depending on the time from when the engine is stopped to when it is restarted by the processing routine of FIG. 7 described later. Will be.

  Next, the fuel concentration data stored in each cell from the 0th cell to the (n-2) th cell is shifted to the next cell and recorded (step S120). That is, the fuel concentration recorded from the 0th to the (n-2) th is shifted and recorded as the fuel concentration data of the 1st to the (n-1) th cells.

  Next, the average density value is stored in the 0th cell corresponding to the entrance area (S122). That is, the fuel concentration E (0) = X1 / c1. In other words, the fuel concentration E (0) is recorded as an average value of the fuel concentration obtained by dividing the integrated value X1 of the fuel concentration detected while the fuel for the unit volume moves by the counter c1 of the number of times of detecting the fuel concentration. Is done.

  Next, the time data stored in each cell from the 0th cell to the (n-1) th cell is shifted to the next cell and recorded (S124). That is, the detection time data recorded from the 0th to the (n-1) th is shifted and recorded as the time data of the 1st to nth cells. Next, the current time t is recorded as time data T (0) in the 0th cell (S126).

  Next, the accumulated fuel movement amount Q1 and the accumulated number counter C1 are initialized to both zero (S128, S130). Next, the fuel injection amount is set according to the fuel concentration E (n) recorded in the nth cell (S112). Thereafter, this routine is repeated, and the current value of the fuel concentration E (n) of the cell is maintained until the newly accumulated fuel movement amount becomes the unit volume, and the fuel injection set based on this concentration is maintained. When the air-fuel ratio control is executed according to the amount and the movement of the fuel for the unit volume is confirmed, the fuel concentration E (n) is again calculated and detected in the cell of the data shift and the inlet region. The average value of the fuel concentration is stored.

In parallel with the processing of FIG. 6 described above, the control device 14 executes a correction coefficient calculation routine shown in FIG. The routine shown in FIG. 7 is a correction coefficient based on the concentration difference before and after the engine start, the concentration distribution in the fuel passage 6 when the engine is stopped on the previous trip, and the elapsed time when there is a start request and the fuel is being switched. k ₂ is calculated, and in other cases, the correction coefficient k _{2 is set} to 1.

  In FIG. 7, the control device 14 first calculates whether a start request for the current trip has been made (S202), and if negative, the process is returned. If there is a start request, it is then determined whether the fuel is being switched (S204). This determination is made based on whether the accumulated fuel consumption from the previous refueling exceeds the volume V1 of the fuel passage 6.

If the determination is affirmative, that is, the fuel is being switched, the starting alcohol concentration ekalc and the engine water temperature ethw are acquired (S206). Next, it is determined whether the difference between the acquired starting alcohol concentration ekalc and the concentration learning value EG at the previous stop is larger than a predetermined reference value (S208). If the difference is larger than the reference value, the correction coefficient k ₂ is the difference in concentration between the previous trip when the engine is stopped and the current trip when the engine is started, and the fuel when the previous trip is stopped. Based on the concentration distribution in the passage 6 and the elapsed time from the engine stop to the start (that is, the soak time), the calculation is performed according to the map stored in the control device 14 (S210).

On the other hand, if the difference is equal to or smaller than the reference value, the correction coefficient k ₂ is set to 1 (S122), the fuel concentration E (n) calculated in the process of FIG. 6 therefore, the engine is stopped and restarted It is no different from the case without it. Further, even if not in a fuel switch in step S204, the correction coefficient k ₂ is set to 1.

  As a result of the above processing, in the first embodiment, when the engine is stopped and restarted, the estimated fuel concentration is corrected based on the output of the fuel property sensor at the time of stopping and restarting. Therefore, even when the diffusion proceeds while the engine is stopped, the fuel concentration can be estimated appropriately.

<Embodiment 2>
A second embodiment of the present invention will be described. In the second embodiment, in a system having a port injection valve and an in-cylinder injection valve, the fuel supply from the in-cylinder injection valve is selected when the calculation end related to the correction of the fuel concentration is after the closing timing of the intake valve. Is. In addition, when the calculation related to the correction is completed before the intake valve closing timing, the fuel supply from the port injection valve is selected from the calculation completion to the intake valve closing timing, and after the intake valve closing timing, the in-cylinder is selected. Select the fuel supply from the injector.

  FIG. 8 is a schematic diagram for explaining the overall configuration of the system according to the second embodiment of the present invention. As shown in FIG. 8, this system has two fuel injection valves for each cylinder: a port injection valve 2 for injecting fuel into the intake port and an in-cylinder injection valve 52 for injecting fuel into the combustion chamber. A first fuel passage 6 communicating with the port injection valve 2 and a second fuel passage 56 communicating with the in-cylinder injection valve 52 are provided. The first fuel passage 6 and the second fuel passage 56 branch near the outlet of the fuel pump 8 and are connected in parallel to each other. A high pressure pump 58 is provided in the second fuel passage 56.

  A fuel flow sensor 10 and a fuel property sensor 12 are provided in the first fuel passage 6, and a fuel flow sensor 60 and a fuel property sensor 62 are provided in the second fuel passage 56. These sensors enable individual flow rate detection and concentration estimation for each fuel passage 6, 56. The remaining mechanical configuration of the second embodiment is the same as that of the first embodiment.

The control performed by the control apparatus 14 of Embodiment 2 is demonstrated. In FIG. 9, the control device 14 first calculates whether a start request for the current trip has been made (S302), and if not, the process is returned. If there is a start request, the starting alcohol concentration ekalc and the engine water temperature ethw are acquired (S304). Next, it is determined whether the difference between the acquired starting alcohol concentration ekalc and the concentration learning value EG at the previous stop is larger than a predetermined reference value (S306). The difference between the starting alcohol concentration ekalc and the concentration learning value EG may be any one of the fuel passages 6 and 56, and both are compared with the reference value and either is larger than the reference value. In this case, it may be configured to be affirmed in step S306. When the difference is larger than the reference value, the correction calculation request flag shown in FIG. 10 is set (= 1), and in response thereto, the density correction calculation including the calculation of the correction coefficient k ₂ is started. (S308). As described above, this calculation is stored in the control device 14 based on the concentration difference between the engine stop of the previous trip and the engine start of the current trip, and the elapsed time from the engine stop to the start (that is, the soak time). Calculated according to the map. Further, the concentration correction calculation here is performed for both the first fuel passage 6 and the second fuel passage 56.

  Next, it is determined whether or not the correction calculation is incomplete (S310). In the first cycle in which the start request is made, the result is affirmed here, and the execution of the port injection is temporarily stopped (S312). Then, the process is looped until the correction calculation is completed (S314).

  When the correction calculation is completed, the correction calculation completion flag shown in FIG. 10 is set (= 1), and in response to this, the starting required injection amount eqst is acquired (S316). This starting required injection amount eqst is calculated by a map based on the fuel concentration (alcohol concentration) corrected by the correction calculation and the starting water temperature ethw acquired in step S304. The startup required injection amount eqst is calculated for both the port required injection amount eqst1 when using the port injection valve 2 and the in-cylinder required injection amount eqst2 when using the in-cylinder injection valve 52.

  Next, based on the acquired required start injection quantity eqst, the required start injection quantity eqst (in-cylinder required injection quantity eqst2 in this case) of the injection start timing required to be supplied by the in-cylinder injection valve 52 is set. An allowable limit einj_limit is calculated (S318). The injection start timing allowable limit einj_limit is the latest injection start timing that is permitted when the in-cylinder injection valve 52 supplies the total required injection amount eqst at the start. When the injection is started later than this, the entire amount is injected. It will not be possible.

  Next, it is determined whether the correction calculation completion timing is before the injection start timing allowable limit einj_limit (S320). If the determination is negative, the in-cylinder injection valve 52 also determines the required starting injection amount eqst (that is, the cylinder). Because the entire required injection amount eqst2) cannot be supplied, the first ignition is skipped (S334).

  When the determination in step S320 is affirmative, that is, when the correction calculation is completed before the injection start timing allowable limit einj_limit, fuel injection is performed by at least one of the port injection valve 2 and the in-cylinder injection valve 52. . First, it is determined whether the correction calculation completion timing is before the intake valve closing timing (IVC) (S322). If the correction calculation completion is after the intake valve closing timing, that is, if the correction calculation completion is after the intake valve closing timing, the corrected injection amount is corrected. Since the fuel supply using the information cannot be performed by the port injection valve 2, the start injection required injection amount eqst (that is, the in-cylinder required injection amount eqst2) is supplied by the in-cylinder injection valve 52. (S330).

  On the other hand, when the determination in step S322 is affirmative, that is, when the correction calculation is completed before the intake valve closing timing, at least part of the fuel supply by the corrected injection amount can be performed by the port injection valve 2. For this reason, in this embodiment, the fuel supply from the port injection valve 2 is selected from the end of the calculation to the closing timing of the intake valve, and the fuel supply from the in-cylinder injection valve 52 is selected after the closing timing of the intake valve. The First, injection by the port injection valve 2 is executed using the information of the port required injection amount eqst1 until the intake valve closing timing (IVC) (S324), and the cylinder is obtained by subtracting the amount of fuel injected. The inner required injection amount eqst2 is corrected (S326). The in-cylinder required injection amount eqst2 thus corrected is supplied by the in-cylinder injection valve 52 after the intake valve is closed (S328).

  Note that if negative in step S310, that is, if the correction calculation has been completed, fuel can be supplied temporally by either port injection or in-cylinder injection, so normal control is performed (S332). Normal control is performed according to the injection range of each injection valve determined in advance according to the required load and the engine speed. For example, during cold start, weak stratified combustion (injection of fuel from the port injection valve 2 in the expansion to intake stroke) and injection of fuel from the in-cylinder injection valve 52 in the latter half of the compression stroke to promote warm-up of the catalyst The air-fuel mixture is stratified and the ignition timing is retarded, thereby increasing the exhaust gas temperature to promote catalyst warm-up and improving cold emission performance. By using both the port injection valve 2 that injects in the expansion to the intake stroke and the in-cylinder injection valve 52 that injects in the first half of the intake stroke so as to achieve an optimal combustion state, a homogeneous air-fuel mixture is produced and the injected fuel is used separately. The air compressed by the heat of vaporization is cooled to improve the charging efficiency and increase the output.At the time of high load operation and cold, air-fuel ratio feedback control is not performed, and homogeneous combustion is performed The correction operation request flag and the correction calculation completion flag is reset for example when stopping i.e. the end of the trip of the engine.

  As a result of the above processing, in the second embodiment, as shown in FIG. 10, when the end of the calculation related to the correction of the fuel concentration is after the intake valve closing timing (IVC), the in-cylinder injection valve 2 Is selected (S322, S330). Therefore, it is possible to appropriately estimate the fuel concentration while ensuring the calculation time for correction.

  In the second embodiment, when the calculation related to the correction of the fuel concentration is completed before the intake valve closing timing (IVC), the fuel supply from the port injection valve 2 is selected from the calculation completion to the intake valve closing timing. The fuel supply from the in-cylinder injection valve 52 is selected after the intake valve closing timing. Therefore, even when a fuel with a high alcohol concentration is used, port injection excellent in low temperature startability can be utilized to the maximum extent.

  Embodiments of the present invention are not limited to the above-described embodiments, but include all modifications, applications, and equivalents included in the spirit of the present invention defined by the claims. Therefore, the present invention should not be construed as being limited, and can be applied to any other technique belonging to the scope of the idea of the present invention.

  For example, the present invention can be suitably applied not only to an engine that can use a gasoline / alcohol mixed fuel but also to other engines that can use a plurality of types of fuels having different properties. The present invention can also be suitably applied to, for example, a two-bank V-type engine. When the fuel passage is branched, the fuel concentration can be estimated for each branch.

2 port injection valve 4 fuel tank 6, 56 fuel passage 8 fuel pump 10, 60 fuel flow sensor 12, 62 fuel property sensor 14 controller 52 in-cylinder injection valve 56 second fuel passage

Claims (3)

Storage means having a plurality of storage cells associated with each of a plurality of passage regions formed by dividing the volume of the fuel passage between the fuel property sensor installed in the fuel passage of the internal combustion engine and the fuel injection valve;
The fuel concentration data according to the output of the fuel property sensor is recorded in the memory cell corresponding to the region closest to the fuel property sensor, and the fuel concentration data stored in each of the memory cells according to the fuel consumption amount is recorded. Each data is shifted to the storage cell corresponding to the previous area in the fuel flow direction, and the fuel injection valve injects the fuel according to the fuel concentration data stored in the storage means and the fuel diffusion coefficient. Concentration estimating means for estimating the fuel concentration immediately before being performed;
An injection amount control means for controlling the fuel injection amount from the fuel injection valve in accordance with the fuel concentration estimated by the concentration estimation means;
An internal combustion engine control device comprising:
And a correction means for correcting the estimated fuel concentration based on the output of the fuel property sensor when the internal combustion engine is stopped and restarted. A control device for an internal combustion engine. A control device for an internal combustion engine according to claim 1,
The internal combustion engine has an in-cylinder injection valve that injects fuel into the combustion chamber, and a port injection valve that injects fuel into the intake port,
The control apparatus for an internal combustion engine, further comprising selection means for selecting fuel supply from the in-cylinder injection valve when the calculation by the correction means is after the closing timing of the intake valve. A control device for an internal combustion engine according to claim 2,
The selection means selects the fuel supply from the port injection valve from the end of the calculation until the closing timing of the intake valve when the end of the calculation by the correction means is before the closing timing of the intake valve, and from the closing timing of the intake valve A control device for an internal combustion engine, which selects fuel supply from a cylinder injection valve later.

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