JP3967712B2 - Fuel injection control device for in-cylinder internal combustion engine - Google Patents

Description

  The present invention relates to an apparatus for controlling the amount of fuel injected into a combustion chamber in an in-cylinder injection internal combustion engine.

  2. Description of the Related Art An in-cylinder injection type internal combustion engine (hereinafter referred to as an engine) that injects fuel directly into a combustion chamber is known. In an in-cylinder injection type engine, fuel is normally boosted with a high-pressure pump, and the boosted fuel is injected into a combustion chamber. The high pressure pump is typically driven in synchronism with engine rotation. Since the engine speed is low when the engine is started, it may be difficult to boost the fuel, which may lead to insufficient fuel supply. This may deteriorate the startability of the engine.

  As a technique for improving such a start-up problem, Patent Document 1 described below describes a technique in which start-up fuel is supplied in advance to all cylinders during engine cranking and ignition is then started. .

On the other hand, it is known that part of the injected fuel adheres to the combustion chamber. A method of correcting the fuel injection amount based on the attached fuel has been proposed (see, for example, Patent Document 2).
Japanese Patent Laid-Open No. 10-18951 Japanese Patent Laid-Open No. 7-127296

  By supplying the starting fuel to all the cylinders in advance when the engine is started, and then starting ignition, the shortage of fuel supply can be solved and the engine startability can be improved. However, part of the starting fuel supplied without ignition may adhere to the combustion chamber or the piston. If the amount of fuel to be injected in the subsequent combustion cycle is calculated without considering this adhered fuel, there is a possibility that a desired air-fuel ratio cannot be realized. This not only deteriorates emissions but also may cause deterioration of startability.

  Accordingly, there is a need for a control device that can appropriately calculate the fuel injection amount for the subsequent combustion in consideration of the fuel adhering due to the fuel injection performed with ignition stopped.

  According to one aspect of the present invention, an apparatus for controlling the amount of fuel injected into a combustion chamber for a direct injection internal combustion engine is supplied to the internal combustion engine based on the current operating state of the internal combustion engine. The amount of fuel to be calculated is calculated as the required fuel amount. The control device injects fuel into the combustion chamber with ignition stopped, and accumulates the fuel in the combustion chamber. The amount of fuel adhering to the combustion chamber due to fuel injection when ignition is stopped is calculated as the amount of adhering fuel. The required fuel is corrected by the amount of adhered fuel, and the amount of fuel to be injected through the fuel injection valve in the next combustion is calculated.

  According to the present invention, the fuel injection amount for the subsequent combustion cycle is calculated in consideration of the fuel adhering to the fuel injection performed with the ignition stopped, so that the air-fuel ratio becomes a desired value. It can be converged.

  According to one embodiment of the present invention, when fuel is injected in a state where ignition is stopped at the time of starting the internal combustion engine, further, according to the fuel pressure detected at the time of starting the internal combustion engine, The amount of fuel adhering to the combustion chamber prior to fuel injection in the ignition stop state is calculated as the remaining adhering fuel amount. The total amount of adhering fuel is calculated by adding the amount of adhering fuel to the amount of adhering fuel. The amount of fuel to be injected through the fuel injection valve in the next combustion is calculated by correcting the required fuel amount by the total adhered fuel amount.

  If the engine is stopped before the engine reaches the warm-up state in the previous operation cycle and then the engine is started without being left for a sufficient time (soak), the fuel injected at the time of engine start in the previous operation cycle Some may remain in the combustion chamber. According to the present invention, the fuel injection amount for the subsequent combustion cycle is calculated in consideration of such remaining attached fuel, so that the air-fuel ratio is prevented from becoming rich with respect to a desired value. Can do.

  Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a configuration diagram of an internal combustion engine and its control device according to one embodiment of the present invention.

  An electronic control unit (hereinafter referred to as “ECU”) 1 includes an input interface 1a that receives data sent from each part of the vehicle, a CPU 1b that executes calculations for controlling each part of the vehicle, and a read-only memory (ROM) ) And a random access memory (RAM) 1c and an output interface 1d for sending control signals to various parts of the vehicle. The ROM of the memory 1c stores a program for controlling each part of the vehicle and various data. A program for realizing the fuel injection control according to the present invention, and data and tables used when executing the program are stored in this ROM. The ROM may be a rewritable ROM such as an EPROM. The RAM is provided with a work area for calculation by the CPU 1b. Data sent from each part of the vehicle and control signals sent to each part of the vehicle are temporarily stored in the RAM.

  The internal combustion engine (hereinafter referred to as “engine”) 2 is a direct injection gasoline engine. The engine 2 can comprise, for example, four cylinders, only one of which is shown. A combustion chamber 5 is formed between the piston 3 of the cylinder and the cylinder head 4. A concave cavity 6 is formed at the center of the upper surface of the piston 3.

  A fuel injection valve 7 and a spark plug 8 are attached to the cylinder head 4 so as to face the combustion chamber 5. The valve opening time of the fuel injection valve 7 is controlled by the ECU 1. The fuel is injected from the fuel injection valve 7 toward the cavity 6 of the piston 3 and collides with the upper surface of the piston 3 including the cavity 6 to form a fuel jet. The spark plug 8 ignites a spark in accordance with a control signal from the ECU 1 and burns the air-fuel mixture in the combustion chamber 5.

  An intake pipe 13 is connected to the engine 2 via an intake valve 12. A throttle valve 14 is provided on the upstream side of the intake pipe 13. The opening degree of the throttle valve 14 is controlled by the ECU 1. A throttle valve opening sensor (θTH) 15 connected to the throttle valve 14 detects the opening of the throttle valve 14 and supplies it to the ECU 1.

  An intake pipe pressure (Pb) sensor 16 and an intake air temperature (Ta) sensor 17 are provided on the downstream side of the throttle valve 14 of the intake pipe 13 and detect the intake pipe pressure Pb and the intake air temperature TA, respectively, and detect them as an ECU 1. Send to.

  The engine water temperature (TW) sensor 18 is attached to a cylinder peripheral wall (not shown) filled with cooling water in the cylinder block of the engine 2, detects the temperature TW of engine cooling water, and sends it to the ECU 1.

  The engine 2 is provided with a crank angle (CRK) sensor 19. The crank angle sensor 19 outputs a CRK signal and a TDC signal, which are pulse signals, to the ECU 1 as the crankshaft rotates. The CRK signal is a pulse signal output at a predetermined crank angle (for example, 30 degrees). The ECU 1 calculates the rotational speed NE of the engine 2 according to the CRK signal. The TDC signal is a pulse signal output at a crank angle related to the TDC position of the piston.

  An exhaust pipe 22 is connected to the downstream side of the engine 2 via an exhaust valve 21. The exhaust pipe 22 is provided with a linear air-fuel ratio sensor (LAF) 23 that detects the air-fuel ratio of the exhaust gas. The linear air-fuel ratio sensor 23 detects a wide range of air-fuel ratios ranging from lean to rich. The detected air-fuel ratio is sent to the ECU 1. Downstream of the linear air-fuel ratio sensor, a three-way catalyst 24 is provided that realizes the maximum purification action for HC, CO, and NOx when the stoichiometric air-fuel ratio is operating.

An O ₂ sensor 25 is provided downstream of the three-way catalyst 24. The O ₂ sensor 25 is a binary exhaust gas concentration sensor. The O ₂ sensor 25 outputs a high-level signal when the air-fuel ratio is richer than the stoichiometric air-fuel ratio, and outputs a low-level signal when the air-fuel ratio is leaner than the stoichiometric air-fuel ratio. The output electrical signal is sent to the ECU 1. An adsorption NOx catalyst 26 is provided downstream of the O ₂ sensor 25. The adsorption NOx catalyst 26 adsorbs NOx in an oxidizing atmosphere and reduces NOx in a reducing atmosphere.

  A signal sent to the ECU 1 is passed to the input interface 1a. The input interface 1a converts an analog signal value into a digital signal value. The CPU 1b processes the converted digital signal, performs an operation according to a program stored in the memory 1c, and generates a control signal to be sent to the actuator of each part of the vehicle. The output interface 1d sends these control signals to the fuel injection valve 7, the spark plug 8, the throttle valve 14, and other actuators.

  FIG. 2 is a block diagram of a high-pressure fuel system from the fuel tank to the fuel injection valve according to an embodiment of the present invention. There are two passages from the fuel tank 31 to the fuel injection valve 7, one is a first passage 37 for supplying fuel from the fuel tank 31 via a high-pressure pump 34, and the other bypasses the high-pressure pump 34. It is the passage 39 to do. An electromagnetic valve 38 is provided in the bypass passage 39, and the opening and closing of the electromagnetic valve 38 is controlled by the ECU 1. A fuel pressure (PF) sensor 40 is provided in the pressure chamber 36, detects the pressure of the injected fuel (fuel pressure), and sends it to the ECU 1.

  The fuel pump 32 is activated in response to the ignition switch being turned on. The fuel adjusted to a predetermined pressure (for example, 0.35 MPa) by the pressure regulator 33 is supplied to the high-pressure pump 34 and the electromagnetic valve 38. The high-pressure pump 34 is connected to the cam shaft of the engine 2 and operates in synchronization with the rotation of the engine 2. The pressure regulator 35 operates so that the output pressure of the high pressure pump 34 is supplied to the pressure chamber 36 until the fuel pressure output from the high pressure pump 34 reaches a predetermined high pressure value (for example, 8 MPa). When the pressure of the fuel output from the high pressure pump 34 is in the vicinity of the predetermined high pressure value, the fuel pressure is operated to be maintained at the high pressure value.

  When the electromagnetic valve 38 is open, the output pressure of the pressure regulator 33 is supplied to the pressure chamber 36, so the fuel pressure PF is low. On the other hand, when the solenoid valve 38 is closed, the output pressure from the high-pressure pump 34 is supplied to the pressure chamber 36, so the fuel pressure PF becomes high. Thus, the fuel pressure PF can be controlled to a low pressure and a high pressure.

  When the engine 2 is not in the start mode, the solenoid valve 38 is closed to control the fuel pressure PF to the high pressure side. When the engine 2 is in the start mode, the fuel pressure may not be increased by the high pressure pump 34 because the engine speed is low. Therefore, when the engine 2 is in the start mode, the solenoid valve 38 is opened to control the fuel pressure PF to the low pressure side.

  FIG. 3 is a diagram conceptually showing a fuel supply mode when the engine 2 is in the start mode according to one embodiment of the present invention. When the ignition of the engine 2 is turned on, cranking is started. During cranking, as shown in the state (a), the starting fuel is supplied to the combustion chambers of all the cylinders. This starting fuel is not ignited.

  After supplying the starting fuel to the combustion chambers of all the cylinders, a normal combustion cycle including intake, compression, expansion, and exhaust stroke is started. When the combustion cycle is started, the starting fuel typically accumulates in the cavity 6 of the piston 3 as shown in state (b). In this state, fuel for realizing a desired air-fuel ratio is injected into the combustion chamber, and ignition is performed.

  When the engine is started, the engine speed is low, so the pressure of the fuel cannot be increased and there is a risk of insufficient fuel supply. In particular, when the outside air is extremely cold, a large amount of fuel is required to start the engine well. According to the present invention, since ignition is started in a state where the starting fuel is added, it is possible to avoid fuel shortage at the time of starting the engine, and thus it is possible to realize a good startability of the engine.

  With reference to FIG. 4, correction of the fuel injection amount by the attached fuel will be described. Assume that Tout (n) of fuel is injected from the fuel injection valve 7 into the combustion chamber in the current combustion cycle. Here, n is an identifier for identifying the combustion cycle.

  Of this fuel injection amount Tout (n), an amount corresponding to (A × Tout (n)) directly contributes to combustion. The remaining amount (1-A) × Tout (n) is taken as an incremental Fwin in the fuel Twp (n−1) already attached in the combustion chamber (formula (1)). Here, A is called a direct rate, and indicates a ratio of fuel directly used for combustion in the current fuel cycle out of the fuel injected in the current combustion cycle, and is given by 0 <A <1.

Fwin (n) = (1-A) × Tout (n) (1)
Of the adhered fuel amount Twp (n−1), an amount corresponding to B × Twp (n−1) contributes to combustion (formula (2)). Here, B is referred to as a carry-off rate, and indicates a ratio of fuel used for combustion in the current combustion cycle in the attached fuel amount Twp (n−1), and is given by 0 <B <1.

Fwout (n) = B × Twp (n-1) (2)
As a result, the value obtained by adding (A × Tout (n)) and Fwout (n) is actually the amount of fuel used for combustion in the current combustion cycle.

  On the other hand, in order to obtain a desired engine output, an amount of fuel to be supplied to the engine in this combustion cycle (referred to as a required fuel amount) Tcyl (n) is determined. The fuel injection amount Tout (n) is calculated so that the required fuel amount Tcyl (n) matches (A × Tout (n)) + Fwout (n) (Equations (3) and (4)). .

Tcyl (n) = A · Tout (n) + Fwout (n) (3)
Tout (n) = (Tcyl (n) −Fwout (n)) / A
= (Tcyl (n) -B * Twp (n-1)) / A (4)
In response to the injection of the fuel injection amount Tout (n), the attached fuel is updated as shown in Expression (5).

Twp (n) = (1-B) × Twp (n-1) + Fwin (n) (5)
In this embodiment, the direct rate A and the carry-off rate B are determined based on the current operating state of the engine (typically, the engine speed NE and the intake pipe pressure PB).

  FIG. 5 is a block diagram of a fuel control device according to an embodiment of the present invention. Each functional block is typically realized by a software program stored in the memory 1c.

  The required fuel calculation unit 51 calculates the required fuel amount Tcyl (n) based on the current operating state of the engine according to the equation (6).

Tcyl (n) = Ti (n) × Ktotal (n) (6)
Ti is a basic fuel, and is determined based on the detected engine speed NE and the intake pipe pressure PB. Ktotal indicates a correction coefficient. Ktotal is determined according to, for example, a correction coefficient Ktw determined according to the engine coolant temperature TW, KAST considered when the engine is started, a correction coefficient KWOT determined according to the engine load state, and the intake air temperature. Calculated by multiplying by KTA, air-fuel ratio correction coefficient KO2, etc.

  The fuel injection amount calculation unit 52 receives the current attached fuel Twp (n−1) from the attached fuel calculation unit 55. The fuel injection amount calculation unit 52 calculates the amount Tout (n) of fuel to be injected in the current combustion cycle according to the above equation (4). In this way, the fuel injection amount Tout (n) is obtained by correcting the required fuel amount Tcyl (n) by the adhered fuel amount Twp (n-1).

  In response to the ignition switch being turned on, the mode selection unit 53 generates a mode signal Mode in which a value of zero is set. The mode signal Mode is sent to the injection valve driving unit 54.

  Further, in each combustion cycle after cranking, the mode selection unit 53 selects one of the intake stroke injection and the compression stroke injection based on the current operating state of the engine. In the intake stroke injection, fuel is injected in the first half of the intake stroke in order to draw air into the combustion chamber. In the intake stroke injection, the air-fuel mixture is uniformly dispersed in the combustion chamber while being uniformly burned in a richer state than stratified combustion. The intake stroke injection is performed when the engine load is relatively large (for example, during acceleration).

  In the compression stroke injection, fuel is injected in the latter half of the compression stroke for compressing the intake air. In the compression stroke injection, stratified combustion is performed in an extremely lean state (for example, the air-fuel ratio is 24 or more) while the air-fuel mixture is biased near the spark plug. The compression stroke injection is performed when the engine load is relatively small (for example, idling operation).

  The mode selection unit 53 generates a mode signal Mode having a value of 1 if the intake stroke injection is selected, and generates a mode signal Mode of 2 if the compression stroke injection is selected. The mode signal is passed to the injection valve driving unit 54.

  If the value of the received mode signal Mode is zero, the injection valve drive unit 54 drives the fuel injection valve 7 so that a predetermined starting fuel Tcyl_start is injected during cranking. The starting fuel Tcyl_start can be determined based on the current operating state of the engine (engine water temperature, intake air temperature, etc.).

  If the value of the received mode signal Mode is 1, in order to realize the intake stroke injection, the fuel injection valve 7 is driven so that the fuel injection amount Tout is injected in response to the arrival of the intake stroke.

  If the value of the received mode signal Mode is 2, in order to realize the compression stroke injection, the fuel injection valve 7 is driven so that the fuel injection amount Tout is injected in response to the arrival of the compression stroke.

  When the ignition cut unit 56 determines that the injected fuel is not ignited, the ignition cut unit 56 prohibits transmission of a control signal to the spark plug 8. In this embodiment, the ignition cut is performed when the ignition switch of the engine is turned on. When the ignition cut unit 56 receives the mode signal Mode having a value of zero, the ignition cut unit 56 prohibits the transmission of the control signal to the spark plug 8 in order to perform the ignition cut. Thereby, the injected starting fuel is stored in the combustion chamber without ignition.

  The attached fuel calculation unit 55 receives the mode signal Mode. If the value of the received mode signal Mode is zero, the amount Twp_igoff of the fuel adhering to the start-up fuel being injected in the ignition cut state is calculated.

  Further, if the attached fuel calculation unit 55 receives the mode signal Mode having a value of zero, the attached fuel calculation unit 55 calculates the amount of attached fuel Twp_remain already remaining in the combustion chamber when the ignition switch is turned on.

  When the engine was started before the engine was warmed up in the previous operation cycle, and then the engine was started without being allowed to stand (soak) for a sufficient period of time, it was injected when the engine was started in the previous operation cycle. Part of the fuel may remain in the combustion chamber. The attached fuel calculation unit 55 calculates such remaining attached fuel Twp_remain.

  The adhering fuel calculation unit 55 adds the adhering fuel Twp_igoff resulting from the injection of the starting fuel and the remaining adhering fuel Twp_remain to calculate the present value Twp (n) of the adhering fuel. The current value Twp (n) of the adhered fuel is used by the fuel injection amount calculation unit 52 to calculate the fuel injection amount Tout (n + 1) for the next combustion.

  If the value of the received mode signal Mode is 1, the attached fuel calculation unit 55 starts calculation for calculating the attached fuel in response to the completion of the intake stroke injection. The adhering fuel calculation unit 55 calculates the increment Fwin (n) of the adhering fuel according to the equation (1) based on the fuel Tout (n) injected during the intake stroke.

  If the value of the received mode signal Mode is 2, the attached fuel calculation unit 55 starts calculation for calculating the attached fuel in response to the completion of the compression stroke injection. The attached fuel calculation unit 55 calculates an increment Fwin (n) of the attached fuel according to the equation (1) based on the fuel Tout (n) injected during the compression stroke.

  The adhered fuel calculation unit 55 adds the increment Fwin (n) calculated in this way to the current amount of adhered fuel “(1−B) × Twp (n−1)”, thereby obtaining the current value Twp of the adhered fuel. (n) is calculated (see equation (5)). The current value Twp (n) of the adhered fuel is used by the fuel injection amount calculation unit 52 to calculate the fuel injection amount Tout (n + 1) for the next combustion.

  In this way, when the fuel is injected in the ignition cut state, the fuel injection amount for subsequent combustion is calculated in consideration of the fuel adhering to the fuel injection. Therefore, it is possible to avoid that the desired air-fuel ratio cannot be realized due to the fuel adhered at the time of ignition cut. Further, since the fuel injection amount for subsequent combustion is calculated in consideration of the adhered fuel remaining in the combustion chamber when the ignition switch is turned on, the fuel injection amount remaining at the start of the engine is empty. It can be avoided that the fuel ratio becomes rich.

  In this embodiment, the ignition cut is performed when the engine is started. Alternatively, the present invention can be applied to a case where the ignition is cut at a time other than when the engine is started. In this case, the attached fuel calculation unit 55 calculates only the attached fuel amount Twp_igoff at the time of ignition cut, and passes this to the fuel injection amount calculation unit 52 as the attached fuel Twp. The calculation of the residual adhesion amount Twp_remain is not required.

  In this embodiment, either the suction stroke injection or the compression stroke injection is performed. Alternatively, other injection modes may be set. For example, when it is determined that the engine load is about “medium”, split injection that performs both the intake stroke injection and the compression stroke injection during one combustion cycle may be set. By setting such split injection, the step difference in engine output between the intake stroke injection and the compression stroke injection can be reduced.

  FIG. 6 shows a flowchart of a process for calculating the fuel injection amount. This process is performed once per combustion cycle. In this example, the process is performed prior to the start of a given combustion cycle “n”.

  In step S1, the required fuel amount Tcyl (n) is calculated according to the above equation (6). In step S2, a direct map A and a carry-off rate B are obtained by referring to a predetermined map based on the detected engine speed NE and intake pipe pressure Pb. In step S3, the adhered fuel Fwout (n) that contributes to combustion in the current combustion cycle is calculated from the adhered fuel amount Twp (n-1) calculated in the previous combustion cycle according to the equation (2).

  In step S4, it is determined whether or not to perform fuel cut in the current combustion cycle. The fuel cut is an operation for stopping the supply of fuel to the engine. If the fuel cut is to be performed in the current combustion cycle, the process proceeds to step S5, where the fuel injection amounts Tout_int (n) and Tout_cmp (n) for intake and compression strokes are set to zero, and the fuel supply is stopped.

  In step S6, the fuel injection amount Tout (n) for combustion in the current combustion cycle is calculated according to the above equation (4).

  In step S7, the value of the mode signal Mode is checked. If the value of the mode signal Mode is zero, the predetermined starting fuel Tcyl_start is set to the starting fuel injection amount Tout_start (S8).

  In step S9, if the value of the mode signal Mode is 1, it indicates that the intake stroke injection is performed. The fuel injection amount Tout calculated in step S6 is set to the fuel injection amount Tout_int for the intake stroke, and zero is set to the fuel injection amount Tout_cmp for the compression stroke (S10).

  In step S11, if the value of the mode signal Mode is 2, it indicates that the compression stroke injection is performed. The fuel injection amount Tout calculated in step S6 is set to the fuel injection amount Tout_cmp for the compression stroke, and zero is set to the fuel injection amount Tout_int for the suction stroke (S12).

  FIG. 7 is a flowchart showing a process for calculating the adhered fuel. This process is performed in response to the completion of fuel injection according to the fuel injection amount calculated in the process of FIG.

  In step S21, the value of the mode signal Mode is checked. If the value of the mode signal Mode is zero, it indicates that the starting fuel has been injected with the ignition cut being performed. In this case, an attached fuel calculation routine for ignition cut (FIG. 8) is executed in step S22.

  In step S23, if the value of the mode signal Mode is 1, it indicates that the intake stroke injection has been performed in the current combustion cycle. Proceeding to step S24, the amount Tout_int (n) of fuel injected in the intake stroke is substituted into a temporary variable tnetftemp.

  If it is not the intake stroke injection, the process proceeds to step S25 to check whether the value of the mode signal Mode is 2. If the value of the mode signal Mode is 2, it indicates that the compression stroke injection has been performed in the current combustion cycle, and the process proceeds to step S26. In step S26, the amount Tout_cmp (n) of fuel injected in the compression stroke is substituted into the temporary variable tnetftemp.

  In step S27, the fuel attached by the injection of the current combustion cycle, that is, the increment Fwin (n) is calculated according to the above equation (1). The direct rate A is obtained in step S2 in FIG.

  Proceeding to step S28, the attached fuel amount is updated according to the equation (5), and the current value Twp (n) of the attached fuel is calculated. This current value Twp (n) is used to execute the calculation of step S3 when the process of FIG. 6 is executed for the next combustion cycle.

  FIG. 8 is a flowchart of a process for calculating the attached fuel when the ignition cut is performed, which is performed in step S22 of FIG.

  In step S41, it is determined whether the initial fuel pressure PF_INI detected by the fuel pressure sensor 40 (FIG. 2) when the ignition switch is turned on is greater than a predetermined value.

  The high pressure fuel system shown in FIG. 2 is sealed. Therefore, after the engine stops, the rate of decrease in fuel pressure is moderate. By checking the fuel pressure, it is possible to estimate the elapsed time since the engine stopped. In step S41, if the initial fuel pressure PF_INI is greater than a predetermined value, it indicates that the time from when the engine is stopped before the engine is warmed up to when the engine is restarted is short. In such a state, the attached fuel may remain in the combustion chamber.

  In step S42, the remaining attached fuel Twp_remain is obtained based on the initial fuel pressure PF_INI and the initial engine water temperature TW_INI detected by the fuel pressure sensor 40 (FIG. 2) and the engine water temperature sensor 18 (FIG. 1) when the ignition switch is turned on. .

  The amount of the remaining adhered fuel Twp_remain depends on the engine water temperature. The lower the engine water temperature, the higher the ratio of fuel adhering to the amount of fuel injected. On the other hand, as described above, the fuel pressure indicates an elapsed time since the engine was stopped. The longer the elapsed time, the more the attached fuel evaporates, and thus the amount of attached fuel decreases. Therefore, the amount of the remaining adhered fuel Twp_remain can be estimated based on the initial fuel pressure PF_INI at the time of starting the engine and the initial engine water temperature TW_INI.

  The amount of remaining adhered fuel corresponding to the fuel pressure and the engine water temperature may be estimated in advance and stored in the memory 1c (FIG. 1) as a map. By referring to the map based on the initial fuel pressure PF_INI and the initial engine water temperature TW_INI, the remaining adhered fuel Twp_remain can be obtained.

  In step S41, if the initial fuel pressure PF_INI is equal to or less than a predetermined value, it can be determined that the engine is sufficiently left and the attached fuel has evaporated. Therefore, in step S43, zero is set to the remaining adhered fuel Twp_remain.

  In step S44, based on the engine water temperature TW detected this time by the engine water temperature sensor, the amount Twp_igoff of the fuel adhering due to the injection of the starting fuel is obtained.

  How much fuel is deposited can be estimated based on how much fuel is vaporized. The degree of fuel vaporization depends on the engine water temperature. Therefore, the amount Twp_igoff of the fuel adhering due to the injection of the starting fuel can be estimated based on the engine water temperature.

  The amount of fuel attached by injection of the starting fuel corresponding to the engine water temperature may be estimated in advance and stored in the memory 1c as a map. The attached fuel Twp_igoff can be obtained by referring to the map based on the engine coolant temperature TW.

  In step S45, the amount Twp_main of the remaining attached fuel calculated in step S42 or S43 and the amount Twp_igoff of the fuel attached due to the injection of the starting fuel are added, and the current value Twp (n) of the attached fuel is added. calculate. This current value Twp (n) is used to execute the calculation of step S3 when the process of FIG. 6 is executed for the next combustion cycle.

  As described above, according to the present invention, the fuel injection amount for the subsequent combustion cycle is calculated based on the amount of fuel adhering to the fuel injected in the ignition cut state. It can prevent becoming richer than a desired value. In addition, since the fuel injection amount for the subsequent combustion cycle is calculated in consideration of the adhered fuel remaining in the combustion chamber when the engine is started, the desired air-fuel ratio is maintained while maintaining good engine startability. Can be realized.

  The present invention can also be applied to other internal combustion engines (for example, outboard motors).

1 schematically shows an internal combustion engine and a control device according to one embodiment of the present invention. FIG. The figure which shows the mechanism from a fuel tank to a fuel injection valve according to one Example of this invention. The figure which shows the fuel supply form at the time of the start mode according to one Example of this invention. The figure which shows the concept of the correction | amendment by the amount of adhesion fuel according to one Example of this invention. The functional block diagram of the fuel-injection control apparatus according to one Example of this invention. The flowchart of the process which calculates the fuel injection quantity according to one Example of this invention. 5 is a flowchart of a process for calculating attached fuel according to an embodiment of the present invention. The flowchart of the process which calculates the adhesion fuel at the time of ignition cut according to one Example of this invention.

Explanation of symbols

1 ECU
2 Engine 3 Piston 5 Combustion chamber 7 Fuel injection valve 40 Fuel pressure sensor

Claims (1)

An apparatus for controlling the amount of fuel injected into a combustion chamber for an in-cylinder internal combustion engine,
Calculation means for calculating the amount of fuel to be supplied to the internal combustion engine as a required fuel amount based on the operating state of the internal combustion engine;
An ignition stop injection means for injecting fuel into the combustion chamber in a state where ignition is stopped at the time of starting the internal combustion engine and storing the fuel in the combustion chamber;
Means for calculating an amount of attached fuel adhering to the combustion chamber prior to fuel injection by the ignition stop time injection means as a residual attached fuel amount in accordance with a fuel pressure detected at the time of starting the internal combustion engine;
Adhered fuel calculating means for calculating the amount of fuel adhering to the combustion chamber as a result of fuel injection by the ignition stop time injection means,
Means for adding the remaining attached fuel amount to the attached fuel amount calculated by the attached fuel calculating means to calculate a total attached fuel amount;
A fuel injection amount calculating means for correcting the required fuel amount by the total adhered fuel amount and calculating an amount of fuel to be injected through a fuel injection valve in the next combustion;
A fuel injection control device for an internal combustion engine, comprising:

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