JP4396517B2 - Start control device for internal combustion engine - Google Patents

Description

  The present invention relates to a start control device for an internal combustion engine represented by an automobile engine or the like. In particular, the present invention relates to an improvement in scavenging control that is executed when the internal combustion engine is not started well.

  For example, in an automobile engine, when starting, a starter motor is driven to perform cranking. Further, along with this cranking, fuel is supplied to the combustion chamber and the ignition plug is ignited, leading to start-up.

  However, if the engine fails for some reason, i.e., the engine fails, the air-fuel ratio of the air-fuel mixture remaining in the combustion chamber becomes too high and ignition combustion becomes difficult. Then, it becomes wet (so-called spark plug fogging state), and subsequent starting becomes more difficult. In particular, during cold start or cranking in a cold region, this tendency is remarkable because control is performed such that a large amount of fuel is supplied into the cylinder to improve startability.

In order to eliminate the problem at the time of such a starting failure, scavenging operation has been conventionally performed as disclosed in, for example, Patent Document 1 and Patent Document 2. In this scavenging operation, when the above-described start failure occurs, cranking is performed in a state where the opening of the throttle valve is set to a predetermined opening or more and the fuel supply is stopped. As a result, unburned fuel in the combustion chamber is discharged (scavenged) from the cylinder, and the subsequent startability can be ensured satisfactorily.
JP 2000-265880 A Japanese Patent Laid-Open No. 10-331691

  By the way, particularly at a very low temperature in a cold region (for example, when the outside air temperature is −25 ° C. or lower), a large amount of fuel is supplied into the cylinder during cranking as described above, and the supplied fuel is vaporized. However, the situation is insufficient. For this reason, there is a high possibility that the fuel remains in the liquid state around the terminal of the spark plug, and when the scavenging operation is executed in such a situation, the fuel `` burns '' around the terminal with the ignition of the spark plug As a result, a large amount of carbon adheres around the terminals. When the carbon is short-circuited between the terminals, the ignition of the spark plug becomes impossible, which causes a problem that maintenance of the spark plug (removal work of attached carbon, etc.) is required. .

In addition, the above Patent Document 1 also discloses that the ignition plug is not ignited (ignition cut) during the scavenging operation. However, in the control in which the ignition plug is not ignited during the scavenging operation, the scavenging operation is completed. Otherwise, the engine cannot be started, and the driver's request for an early start of the engine cannot be met. In other words, if the spark plug is ignited during the scavenging operation, the engine can be started when the scavenging proceeds to some extent and the air-fuel ratio in the combustion chamber reaches an ignitable range (the engine starts during the scavenging operation). It can be expected that the engine will start early. However, as in Patent Document 1, in the case where the spark plug is not ignited during the scavenging operation, the engine does not start even if the air-fuel ratio in the cylinder reaches an ignitable range during the scavenging operation. The engine cannot be started until after the scavenging operation is completed. On the other hand, if the spark plug is always ignited during the scavenging operation so that the engine can be started at an early stage, as described above, the fuel “burns” around the terminal of the spark plug, resulting in an unignitable state. In this case, it is impossible to meet the demand for starting the engine reliably.

  As described above, in the conventional scavenging operation, if the engine is started early, the startability of the engine may be impaired. On the other hand, the startability of the engine is ensured. When trying to do so, there was a problem that the engine start was delayed.

  The present invention has been made in view of such a point, and the object of the present invention is to enable early start of the internal combustion engine while enabling the early start of the internal combustion engine with respect to the internal combustion engine that executes the scavenging control at the time of the start failure. An object of the present invention is to provide a start control device that improves the startability of an internal combustion engine and enables a reliable start in an impossible situation.

  The solution of the present invention taken to achieve the above object is that the internal combustion engine does not start even if cranking with fuel supply into the combustion chamber and ignition of the spark plug is performed for a predetermined period or more. Further, it is premised on a start control device for an internal combustion engine that performs a scavenging operation for cranking in a state where fuel supply is stopped or reduced. An engine temperature detecting means for detecting the engine temperature and an ignition plug during the scavenging operation when the engine temperature detected by the engine temperature detecting means exceeds a predetermined ignition cut temperature. And ignition control means for prohibiting ignition of the spark plug during the scavenging operation when the engine temperature is equal to or lower than the ignition cut temperature.

  Due to this specific matter, when the scavenging operation is performed after the start-up failure has occurred, if the engine temperature detected by the engine temperature detecting means exceeds the ignition cut temperature, the ignition plug is ignited during the scavenging operation. This is because when the engine temperature exceeds the ignition cut temperature, scavenging proceeds to some extent and the internal combustion engine starts when the air-fuel ratio in the combustion chamber reaches an ignitable range (the internal combustion engine starts during the scavenging operation). This is to make it possible to start the engine early. On the other hand, when the engine temperature is equal to or lower than the ignition cut temperature, ignition of the spark plug during the scavenging operation is prohibited. This is because when the engine temperature is equal to or lower than the ignition cut temperature, a large amount of fuel is supplied into the cylinder at the time of cranking before the start failure occurs, and the supplied fuel is not sufficiently vaporized. Therefore, in this situation, if the spark plug is ignited during the scavenging operation, the fuel “burns” around the terminal as the spark plug ignites, and a large amount of carbon adheres around the terminal and ignition occurs. This is for avoiding such a situation and ensuring reliable startability after completion of the scavenging operation.

  As described above, according to the present solution, the situation in the cylinder is estimated from the engine temperature when the start failure occurs and the operation shifts to the scavenging operation, and the ignition plug is appropriately controlled according to the situation in the cylinder. Thus, it is possible to ensure a reliable startability after the scavenging operation in a situation where the early start of the internal combustion engine is realized as much as possible and in a situation where this early start is impossible.

  Specifically, the setting operation of the execution time (scavenging duration) of the scavenging operation is such that the scavenging operation duration is set longer as the engine temperature detected by the engine temperature detecting means is lower.

When the engine temperature is relatively high, relatively little fuel is supplied into the cylinder during cranking and its vaporization is promoted. Further, the cranking rotation speed during the scavenging operation is also relatively high, and scavenging is promoted. For this reason, even if the duration of the scavenging operation is made relatively short, the inside of the cylinder is scavenged well. On the other hand, when the engine temperature is relatively low, a relatively large amount of fuel is supplied into the cylinder during cranking in order to improve startability, and the vaporization thereof is insufficient. Further, since the cranking rotation speed during the scavenging operation is also relatively low, the scavenging efficiency tends to decrease. For this reason, in this solution, in a situation where the engine temperature is relatively low, the scavenging operation is continued for a relatively long time so that reliable scavenging can be performed.

  An example of the internal combustion engine to which the present invention is applied is a direct injection type internal combustion engine. That is, a fuel injection valve that supplies fuel directly injects fuel toward the combustion chamber of the internal combustion engine. In such an in-cylinder direct injection internal combustion engine, a path and a period for vaporizing fuel droplets to be injected into the intake path are short, and can remain in the combustion chamber in a liquid phase. High nature. That is, when a starting failure occurs, there is a high possibility that the periphery of the spark plug terminal will be wet with the liquid fuel. By applying the present invention to such an internal combustion engine, a situation in which a large amount of carbon adheres around the terminal of the spark plug can be reliably avoided, and the startability of the internal combustion engine can be improved.

  The ignition cut temperature is set to “−25 ° C.”, for example. In other words, the scavenging operation is performed in which ignition of the spark plug is prohibited during cold start in a cold region where the outside air temperature is low. In particular, if the spark plug is ignited in a scavenging operation when a start-up failure occurs in such a low temperature state, fuel “sagging” occurs around the terminal of the spark plug, and a large amount of carbon adheres around the terminal. Therefore, only in this environment, ignition of the spark plug during the scavenging operation is prohibited, and in other environments, the spark plug is ignited to give priority to the early start of the internal combustion engine. I am doing so.

  In the present invention, the ignition plug is controlled in accordance with the engine temperature when the start failure occurs to shift to the scavenging operation. In other words, the scavenging operation is performed while the ignition plug is ignited in a situation where the internal combustion engine can be started early, while the scavenging operation is performed without igniting the ignition plug in a situation where the internal combustion engine cannot be started early. ing. As a result, it is possible to ensure a reliable startability of the internal combustion engine in a situation where this early start is impossible while realizing an early start of the internal combustion engine as much as possible.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the present embodiment, a case where the present invention is applied to an in-cylinder direct injection multi-cylinder (for example, four-cylinder) gasoline engine mounted on an automobile will be described.

-Outline configuration of engine-
FIG. 1 shows a schematic configuration of an engine (internal combustion engine) 1 according to the present embodiment. As shown in FIG. 1, the intake system of the engine 1 includes an intake passage 2, and a throttle valve 3 is provided in the intake passage 2 downstream of an air cleaner (not shown). A throttle motor 4 which is an actuator for driving the throttle valve 3 is provided at one end of the rotation shaft of the throttle valve 3, and a throttle opening for detecting the opening degree of the throttle valve 3 is provided at the other end. A degree sensor 5 is provided. That is, the opening degree of the accelerator pedal 14 is detected by the accelerator opening degree sensor 15, and the accelerator opening degree signal and control signals of various electronic control devices attached to the engine 1 are sent to an ECU (engine control unit) 10 described later. The throttle valve 3 is configured as an electronically controlled throttle that is inputted to calculate the optimum throttle opening and adjusts the opening by the throttle motor 4 based on the calculated value.

  An atmospheric pressure sensor 18 is disposed upstream of the throttle valve 3 in the intake passage 2, while a surge tank 6 is disposed downstream of the throttle valve 3. A pressure sensor 7 for detecting the intake pressure is provided in the surge tank 6. Further, each cylinder is provided with a fuel injection valve (injector) 8 for directly injecting fuel into the combustion chamber and an ignition plug (ignition plug) 30 for igniting the air-fuel mixture in the combustion chamber.

  A cooling water passage (water jacket) 9 in the cylinder block of the engine 1 is provided with a water temperature sensor (engine temperature detecting means) 11 for detecting the temperature of the cooling water. The water temperature sensor 11 generates an electrical signal having an analog voltage corresponding to the temperature of the cooling water.

The exhaust system of the engine 1 is provided with an exhaust passage 12, and the exhaust passage 12 is provided with a three-way catalytic converter (not shown) for purifying HC, CO, NOx which are harmful components in the exhaust gas. ing. Further, an O ₂ sensor 13 which is a kind of air-fuel ratio sensor is provided in the exhaust passage 12 upstream of the catalytic converter. The O ₂ sensor 13 transmits an electrical signal corresponding to the oxygen component concentration in the exhaust gas.

The output signal of the throttle opening sensor 5, the output signal of the pressure sensor 7, the output signal of the water temperature sensor 11, and the output signal of the O ₂ sensor 13 are obtained from an EC having a built-in microcomputer.
Input to U10. Further, the ECU 10 includes an accelerator pedal depression amount signal from the accelerator opening sensor 15 (the accelerator opening signal) and a key position signal (accessory position, on position, starter) from the ignition switch 17 connected to the battery 16. A signal for determining the position), a top dead center signal TDC from a crank position sensor 21 disposed in proximity to a crankshaft timing pulley attached to one end of the crankshaft and a rotation-integrated timing rotor 24, or at predetermined angles. The crank angle signal CA and the lubricating oil temperature signal from the oil temperature sensor 22 are input.

  In addition, a ring gear 23 provided at the other end of the crankshaft is connected to a starter 19 that is started when the engine 1 is started. The engine 1 is cranked by the rotation of the ring gear 23 when the starter 19 is started. It has come to be.

  The engine speed Ne is obtained by measuring the interval (time) of the predetermined crank angle signal CA. On the outer peripheral surface of the timing rotor 24, there are provided signal teeth 25 comprising 34 teeth provided with two missing teeth portions 26 for detecting the top dead center. The crank position sensor 21 is constituted by an electromagnetic pickup and outputs a crank rotation signal every 10 °. The crank position sensor 21 can detect an accurate top dead center by detecting a signal of a portion where the missing tooth portion 26 is formed. Further, the cylinder in which fuel injection is performed can be discriminated by a signal from the crank position sensor 21 and a signal from a cam position sensor (not shown).

  The starter 19 configured to include a direct current motor is connected to the battery 16 via a starter drive circuit 20. The starter drive circuit 20 does not connect the starter 19 to the battery 16 unless the starter signal ST from the ECU 10 is input. For this reason, when the ignition switch 17 is set to the starter position, the starter 19 is activated and cranking of the engine 1 is started. When the engine 1 starts operation, the ECU 10 is energized, the program is started, the output from each sensor is taken in, and the throttle motor 4 and the fuel injection valve 8 that open and close the throttle valve 3 or other actuators are controlled. . The ECU 10 includes an A / D converter that converts an analog signal from various sensors into a digital signal. A memory such as a CPU 102, a ROM 103, and a RAM 104 to be performed, a clock 105, and the like are provided, and these are connected to each other via a bus 106. Since the configuration of the ECU 10 is publicly known, further explanation is omitted.

-Scavenging control-
When the starter 19 is activated and cranking is performed, the engine 1 according to the present embodiment performs a scavenging operation when a start failure, that is, when the start fails. This scavenging operation is executed when the engine 1 is not started even if the cranking (cranking for supplying fuel into the cylinder and igniting the spark plug 30) is performed for a predetermined period or longer. This is performed in order to ensure good startability thereafter by discharging (scavenging) the unburned fuel in the combustion chamber from the cylinder.

  In this embodiment, a “scavenging control execution flag” for determining whether or not to execute the scavenging operation and an “ignition cut flag” for determining whether or not the spark plug 30 is ignited during the scavenging operation. Is set according to various conditions. Hereinafter, the setting operation of these flags will be described.

<Setting of scavenging control execution flag>
FIG. 2 is a flowchart showing a procedure for setting a scavenging control execution flag (FSCV). The routine shown in FIG. 2 is executed every predetermined time, for example, every several ms, in the initial routine only when the engine 1 is started. Alternatively, it may be executed every predetermined crank angle.

  The scavenging control is performed when cranking is executed for a predetermined time by the starter 19 when the ignition switch 17 is turned on, but the engine 1 is not started. That is, in the scavenging control, when the engine 1 does not start even if the cranking is continued for a predetermined period when the engine 1 is cold started, the fuel continuously injected from the fuel injection valve 8 is excessively put into the combustion chamber. This is intended to eliminate the situation in which the start-up is difficult, and the fuel injection from the fuel injection valve 8 is stopped and the unburned fuel in the combustion chamber is scavenged to improve the startability. In the present embodiment, fuel injection from the fuel injection valve 8 is stopped while the scavenging control execution flag is set to “1”.

  In setting the scavenging control execution flag, it is first determined in step ST1 whether cranking is in progress. If not, the process proceeds to step ST2, and it is determined whether or not the scavenging control execution flag is already “1”. This determination takes into account the case where the ignition switch 17 is once returned from the starter position when the engine 1 does not start even if cranking is continued. That is, when the scavenging control execution flag is set to “1” during the first cranking, the cranking duration Tc described later is set in consideration of the case where the ignition switch 17 is again set to the starter position. The value is not cleared. Therefore, if it is determined that “scavenging control execution flag = 1” in step ST2 (YES determination), this routine is terminated as it is.

  On the other hand, if “scavenging control execution flag = 0” is determined (NO determination) in step ST2, it is determined that cranking has not yet been performed, and the process proceeds to step ST3, where the value of the cranking time counter is cleared. The cranking duration Tc is set to “0”. In subsequent step ST4, the value of the scavenging control execution flag is set to “0”, and this routine is terminated.

  If it is determined in step ST1 that the engine 1 is cranking (YES determination), the process proceeds to step ST5, the cranking duration Tc is calculated using the cranking time counter, and the process proceeds to step ST6. In step ST6, it is determined whether or not the value of the cranking continuation time Tc is equal to or greater than the reference time MN. The reference time MN is determined to be slightly longer than the longest time generally required from the start of cranking to the start of the engine 1, for example. If Tc <MN in step ST6 (NO is determined), the process proceeds to step ST4, the scavenging control execution flag is set to “0”, and this routine is terminated. In this step ST6, Tc ≧ MN. If (YES determination), the process proceeds to step ST7.

  In step ST7, it is determined whether or not the value of the cranking continuation time Tc is equal to or less than the scavenging end time MX obtained by adding the scavenging continuation time L to the reference time MN. The determination in step ST7 is for stopping the scavenging control when the scavenging control continues for a predetermined time L. That is, the timing for returning the value of the scavenging control execution flag to “0” is determined. Therefore, if Tc ≦ MX (YES is determined) in step ST7, the process proceeds to step ST8, the scavenging control execution flag is set to “1”, and this routine is terminated. However, Tc> MX is satisfied (NO determination) At step ST4, the value of the scavenging control execution flag is set to “0”, and this routine is terminated.

  Thus, in this embodiment, when the cranking of the engine 1 is performed, the scavenging control is executed only when the engine 1 does not start and the cranking duration Tc is MN ≦ Tc ≦ MX. It has become.

  The scavenging continuation time L is set according to the cooling water temperature detected by the water temperature sensor 11. Specifically, the duration L of the scavenging operation is set longer as the cooling water temperature is lower. The reason is that when the cooling water temperature is relatively high, the fuel supplied into the cylinder during the cranking is relatively small, and the vaporization thereof is promoted. Further, the cranking rotation speed during the scavenging operation is also relatively high, and scavenging is promoted. For this reason, even if the duration L of the scavenging operation is made relatively short, the inside of the cylinder is scavenged well. On the other hand, when the cooling water temperature is relatively low, the fuel supplied into the cylinder during cranking is relatively large and the vaporization thereof is insufficient to improve the startability. Further, since the cranking rotation speed during the scavenging operation is also relatively low, the scavenging efficiency tends to decrease. For this reason, in this embodiment, as the cooling water temperature is relatively low, the duration L of the scavenging operation is lengthened so that reliable scavenging can be performed. The fluctuation range of the duration L of the scavenging operation is adjusted, for example, between 10 and 20 seconds.

<Ignition cut flag setting>
FIG. 3 is a flowchart showing the procedure for setting the ignition cut flag set by the ignition control means in the present invention. The routine shown in FIG. 3 is also executed at predetermined time intervals, for example, every few ms, in the initial routine only when the engine 1 is started. Alternatively, it may be executed every predetermined crank angle.

  First, in step ST11, it is determined whether or not the scavenging control execution flag is “1”. That is, it is determined whether or not the scavenging control is executed. Here, when the scavenging control execution flag is “0”, that is, when the scavenging control is not executed (NO determination), it is determined that the engine 1 is still being cranked or the engine 1 has started well. In step ST12, the ignition cut flag is set to “0” and this routine is terminated.

  On the other hand, when the scavenging control execution flag is “1” in step ST11, that is, when scavenging control is executed (YES determination), the coolant temperature is read by the output signal from the water temperature sensor 11. In step ST14, it is determined whether or not the read cooling water temperature is −25 ° C. or lower. That is, it is determined whether or not the engine temperature is extremely low. This is, for example, to determine whether or not it is a cold start time in a cold region under a situation where the outside air temperature is low.

If the cooling water temperature exceeds -25 ° C. (NO is determined), the ignition cut flag is set to “0” in step ST12, and this routine is terminated. That is, when the coolant temperature exceeds -25 ° C, if the spark plug 30 is ignited during the scavenging operation,
When the scavenging progresses to some extent and the air-fuel ratio in the combustion chamber reaches an ignitable range, the engine may start (the engine starts during the scavenging operation), and the engine 1 can be started early. Therefore, in a situation where the coolant temperature is relatively high, the ignition cut flag is set to “0” so that the spark plug 30 ignites during the scavenging operation.

  On the other hand, if the coolant temperature is −25 ° C. or lower (YES is determined), the ignition cut flag is set to “1” in step ST15. That is, when the cooling water temperature is −25 ° C. or less, a large amount of fuel is supplied into the cylinder at the time of cranking before the occurrence of the start failure, and the supplied fuel is insufficiently vaporized. In this situation, if the ignition plug 30 is ignited during the scavenging operation, fuel “surrection” occurs around the terminal as the ignition plug 30 is ignited, and a large amount of carbon adheres around the terminal and ignites. May fall into an impossible situation. For this reason, the ignition cut flag is set to “1” so as to prohibit ignition of the spark plug 30 during the scavenging operation when the coolant temperature is extremely low.

<Scavenging operation>
Next, the scavenging operation based on the scavenging control execution flag and the ignition cut flag set as described above will be described with reference to the flowchart shown in FIG. The routine shown in FIG. 4 is also executed at predetermined time intervals, for example, every few ms, in the initial routine only when the engine 1 is started. Alternatively, it may be executed every predetermined crank angle.

  First, in step ST21, the scavenging control execution flag and the ignition cut flag are read. Thereafter, in step ST22, it is determined whether or not the scavenging control execution flag is “1”. That is, it is determined whether or not the scavenging control is executed. When the scavenging control execution flag is “0”, that is, when the scavenging control is not executed (NO determination), this routine is ended. On the other hand, when the scavenging control execution flag is “1”, that is, when scavenging control is executed (YES determination), the process proceeds to step ST23 to determine whether or not the ignition cut flag is “1”. To do.

  If the ignition cut flag is “0” (NO is determined), the process proceeds to step ST24, where the scavenging operation is performed in the scavenging operation mode in which the fuel injection is stopped. That is, the scavenging operation for igniting the spark plug 30 is executed. This is a situation in which the cooling water temperature exceeds -25 ° C., and the scavenging operation in which the engine 1 may start during the scavenging operation is performed by igniting the spark plug 30 during the scavenging operation. Is.

  On the other hand, if the ignition cut flag is “1” in step ST23 (YES is determined), the process proceeds to step ST25, and scavenging in the scavenging operation mode in which the fuel injection is stopped and the spark plug 30 is not ignited. Operation is performed. This is a situation in which the cooling water temperature is -25 ° C. or lower, and the ignition plug 30 is not ignited during the scavenging operation, thereby avoiding “burning” of fuel around the terminal and starting the engine 1 after the scavenging operation is completed. The scavenging operation is performed in order to ensure a good quality.

  FIG. 5 is a time chart showing changes in the starter signal, fuel injection, scavenging control execution flag, ignition cut flag, and engine speed in the present embodiment.

As shown in FIG. 5, when the ignition switch 17 is operated to the starter position at time T <b> 0, the starter signal becomes “1” and the starter 19 starts cranking. Along with this, fuel injection from the fuel injection valve 2 (start of fuel injection from time T1 in FIG. 5) and ignition of the spark plug 30 are performed, and the starting operation of the engine 1 is started. When the engine 1 is normally started (complete explosion) by this starting operation, the scavenging operation is not performed. The change state of the engine speed in this case is indicated by a one-dot chain line in FIG. When the engine 1 starts normally in this way, the scavenging control execution flag and the ignition cut flag are maintained at “0”, and the fuel injection from the fuel injection valve 2 and the ignition operation of the spark plug 30 are continued. .

  On the other hand, if the engine 1 does not start even when the time “T0 + MN” is reached, it is determined that the engine has failed, and at the time “T0 + MN”, the scavenging control execution flag is set to “1” and the fuel is discharged. The fuel injection from the injection valve 2 is stopped. At this time, it is determined whether or not the cooling water temperature exceeds -25 ° C. If it exceeds -25 ° C, the ignition cut flag is maintained at "0" (the ignition cut flag shown in FIG. When the temperature is −25 ° C. or lower, the ignition cut flag is set to “1” (the broken line state of the ignition cut flag shown in FIG. 5). In this manner, the scavenging operation is performed with each flag set.

  When the engine is shifted to the scavenging operation with the ignition cut flag set to “0”, the engine is started when the scavenging proceeds to some extent and the air-fuel ratio in the combustion chamber reaches an ignitable range (during the scavenging operation). May start the engine). The change state of the engine speed at that time is shown by a solid line in FIG. In this way, when the engine is started during the scavenging operation, the scavenging operation is immediately stopped and the normal engine control is started. That is, the scavenging control execution flag is returned to “0” to restart the fuel injection.

  On the other hand, when the ignition cut flag is set to “1” and the scavenging operation is started, the scavenging operation in the state where the fuel injection and ignition of the spark plug 30 are stopped is continued until the time “T0 + MX” in the figure. When the time “T0 + MX” is reached, the scavenging control execution flag and the ignition cut flag are returned to “0”, and a second cranking operation (cranking by fuel injection and ignition of the ignition plug 30) is started. In this case, since the inside of the cylinder is scavenged well, the engine 1 starts well. The change state of the engine speed at that time is shown by a broken line in FIG.

  As described above, in the present embodiment, when the scavenging operation is performed after the start-up failure has occurred, the spark plug 30 is ignited during the scavenging operation when the cooling water temperature exceeds −25 ° C. When the water temperature is −25 ° C. or lower, ignition of the spark plug 30 during the scavenging operation is prohibited. In other words, when the cooling water temperature is high, there is a possibility that the engine 1 starts when the scavenging proceeds to some extent and the air-fuel ratio in the combustion chamber reaches an ignitable range (the engine 1 starts during the scavenging operation). In this case, since the engine 1 can be started early, the spark plug 30 is ignited. On the other hand, when the cooling water temperature is low, a large amount of fuel is supplied into the cylinder at the time of cranking before the start failure occurs, and the supplied fuel is insufficiently vaporized. In this situation, if the spark plug 30 is ignited during the scavenging operation, a large amount of carbon may adhere to the periphery of the terminal, resulting in a situation in which ignition is impossible. The ignition of the spark plug 30 is prohibited in order to ensure reliable startability after the operation is completed. As described above, in this embodiment, it is possible to provide a start control device that enables an early start of the engine 1 but improves the startability of the engine 1 in a situation where the early start is not possible, thereby enabling a reliable start. Is possible.

-Other embodiments-
In the embodiment described above, the case where the present invention is applied to an in-cylinder direct injection type four-cylinder gasoline engine mounted on an automobile has been described. The present invention is not limited to this, and can be applied to a gasoline engine having any other number of cylinders such as a direct injection type 6-cylinder gasoline engine. Further, the present invention is not limited to the in-cylinder direct injection type, and can be applied to an engine that injects fuel into the intake pipe. Furthermore, the engine to which the present invention is applicable is not limited to an automobile engine.

In the above-described embodiment, the fuel injection is completely stopped during the scavenging operation. However, the present invention is not limited to this, and the present invention can also be applied to a device that reduces the fuel injection during the scavenging operation. is there.

  Further, the present invention can also be applied to a so-called hybrid vehicle in which an internal combustion engine and a traveling electric motor are mounted and the vehicle travels with one or both of the driving forces.

It is a figure showing a schematic structure of an engine concerning an embodiment. It is a flowchart figure which shows the setting procedure of a scavenging control execution flag. It is a flowchart figure which shows the setting procedure of an ignition cut flag. It is a flowchart for demonstrating operation | movement of scavenging operation control. FIG. 7 is a time chart showing transitions of a starter signal, a fuel injection state, a scavenging control execution flag, an ignition cut flag, and an engine speed during scavenging operation control.

Explanation of symbols

1 engine (internal combustion engine)
8 Fuel injection valve 11 Water temperature sensor (Engine temperature detection means)
30 Spark plug

Claims (4)

When the internal combustion engine does not start even if cranking with fuel supply to the combustion chamber and ignition of the spark plug is performed for a predetermined period or longer, the scavenging operation is performed in which the fuel supply is stopped or reduced. In the internal combustion engine start control device,
Engine temperature detecting means for detecting the engine temperature;
When the engine temperature detected by the engine temperature detecting means exceeds a predetermined ignition cut temperature, the ignition plug is ignited during the scavenging operation, while when the engine temperature is equal to or lower than the ignition cut temperature. An internal combustion engine start control device comprising ignition control means for prohibiting ignition of the spark plug during the scavenging operation. In the internal combustion engine start control device according to claim 1,
A start control device for an internal combustion engine, characterized in that the duration of the scavenging operation is set longer as the engine temperature detected by the engine temperature detecting means is lower. In the start control device for an internal combustion engine according to claim 1 or 2,
A start control device for an internal combustion engine, wherein the fuel injection valve for supplying the fuel directly injects fuel toward the combustion chamber of the internal combustion engine. In the internal combustion engine start control device according to claim 1, 2, or 3,
An ignition control device for an internal combustion engine, characterized in that the ignition cut temperature is set to “−25 ° C.”.

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