JP2010043570A - Fuel injection control device of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To restrain starting performance of an internal combustion engine from worsening since combustion of a fuel is not suitably carried out at cylinders of a group of back-stroke cylinders after starting the internal combustion engine under a situation that volatility of the fuel is reduced. <P>SOLUTION: Each of cylinders of the engine 1 is classified into a group of a front stroke cylinders or a group of back stroke cylinders. The group of front stroke cylinders is a group of cylinders which can perform fuel injection of quantity corresponding to an injection quantity command value at the starting (an amount of fuel injection required for starting the engine 1) until the first half of a valve-opening period of a first intake valve 13 after determining a crank angle at the starting. The group of back stroke cylinders is a group of cylinders which can not perform fuel injection of quantity corresponding to the injection quantity command valve at the starting until the first half of a valve-opening period of the first intake valve 13 after determining the crank angle. Further, group injection is carried out on both the group of front stroke cylinders and the group of back stroke cylinders, the injection quantity command value at the starting on the group of back stroke cylinders becomes a value increased in quantity and corrected from the injection quantity command value at the starting on the group of front stroke cylinders. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a fuel injection control device for an internal combustion engine.

  In a multi-cylinder internal combustion engine such as an automobile engine, a fuel injection valve that injects fuel from an intake passage toward a combustion chamber is provided for each cylinder. When such an internal combustion engine is started, the fuel injection amount required for starting the engine is calculated as a starting injection amount command value, and after the crank angle is determined by cranking for starting the engine, the fuel injection valve of each cylinder is An amount of fuel corresponding to the starting injection amount command value is injected from the intake passage toward the combustion chamber through drive control.

  After the cranking is started and the crank angle is determined, in order to efficiently supply the amount of fuel corresponding to the start-time injection amount command value to the combustion chamber of each cylinder, the start-time injection amount It is preferable that fuel injection of an amount corresponding to the command value is completed by the first half of the valve opening period of the intake valve after the determination of the crank angle. This is because, when fuel injection of an amount corresponding to the start-time injection amount command value is continued until the first half of the valve opening period of the intake valve, the combustion chamber is closed by the valve closing operation from the full opening of the intake valve in the second half of the valve opening period. This is because the supply of fuel to the combustion chamber is hindered, or the supply of fuel to the combustion chamber is blocked by the closing of the intake valve, which prevents the fuel from being supplied efficiently.

  In the multi-cylinder internal combustion engine, each cylinder of the engine is divided into a front stroke cylinder group and a back stroke cylinder group. Here, the front stroke cylinder group is a cylinder that can perform fuel injection in an amount corresponding to the start-time injection amount command value by the first half of the valve opening period of the first intake valve after the determination of the crank angle. It is a cylinder group. Further, the back stroke cylinder group is a cylinder that cannot perform fuel injection in an amount corresponding to the starting injection amount command value by the first half of the valve opening period of the first intake valve after the determination of the crank angle. It is a cylinder group.

  After the cranking is started and the crank angle is determined, an amount of fuel corresponding to the starting injection amount command value is efficiently supplied to the combustion chamber of each cylinder. In order to improve the starting, it is conceivable to perform the fuel injection in an amount corresponding to the starting injection amount command value by the fuel injection valve of each cylinder by the following intake synchronous injection. That is, in each cylinder, the amount of fuel injection corresponding to the starting injection amount command value from the fuel injection valve in the first half of the intake valve opening period, in other words, the starting injection amount command value from the intake passage to the combustion chamber The fuel injection is started so that the fuel injection of the amount corresponding to is completed. By performing the fuel injection in this way, it is possible to efficiently supply the fuel to the combustion chamber and improve the start of the internal combustion engine by the combustion of the fuel.

  As described above, when the intake synchronous injection for starting the engine is performed, first, the fuel injection is sequentially started in each cylinder of the front stroke cylinder group, and then the fuel injection is sequentially started in each cylinder of the back stroke cylinder group. It will be. For this reason, if the engine rotation speed suddenly increases with the combustion of fuel in the cylinders of the front stroke cylinder group, the intake valve of the back stroke cylinder group starts from the fuel injection start timing in the cylinders of the back stroke cylinder group as the engine rotation speed suddenly increases. Since the time until the first period of the valve opening period (the first period of the second valve opening period after the start of the start) is shortened, there is a possibility that the fuel corresponding to the start-time injection amount command value cannot be injected. If the amount of fuel corresponding to the starting injection amount command value cannot be injected in the cylinders of the reverse stroke cylinder group in this way, it becomes difficult to perform combustion of the fuel well in the combustion chamber. Startability may also deteriorate.

  In order to cope with such a problem, after cranking is started and the crank angle is determined, it is conceivable to perform group injection as shown in Patent Document 1 instead of the intake synchronous injection described above. Specifically, in the cylinders of the front stroke cylinder group, fuel injection is performed in an amount corresponding to the start-time injection amount command value in the same manner as the intake-synchronized injection, and the start timing of the fuel injection is also the intake-synchronized injection. The timing is the same as the injection. Further, in the cylinders of the reverse stroke cylinder group, the cylinders of the front stroke cylinder group in which the start timing and the injection time of the fuel corresponding to the starting injection amount command value are the same piston position as the piston position of the cylinder This is the same as the fuel injection start timing and injection time.

Therefore, in the group injection, cylinders having the same piston position in the front stroke cylinder group and the reverse stroke cylinder group form one group, and in the cylinders of the same group, an amount of fuel corresponding to the start injection amount command value is obtained. Injection is performed at the same start timing and injection time. By performing group injection in this manner, fuel injection in an amount corresponding to the start-time injection amount command value is performed earlier in the cylinders of the reverse stroke cylinder group than the intake synchronous injection. For this reason, when the engine speed increases rapidly due to fuel combustion in the cylinders of the front stroke cylinder group after the start of engine startup, the intake valve opening period of the cylinders in the back stroke cylinder group is the first period (the second opening after the start of engine start). It is possible to prevent the amount of fuel corresponding to the start-time injection amount command value from being injected by the first period of the valve period).
JP-A-7-158482 (paragraphs [0019] and [0030])

  After cranking is started and the crank angle is determined, fuel injection of an amount corresponding to the start-time injection amount command value in each cylinder is realized by the above-described group injection. It becomes possible to prevent the amount of fuel corresponding to the start-time injection amount command value from being unable to be injected before the intake valve opening period first period (the second valve opening period first period after starting).

  However, if the above-described group injection is performed when the volatility of the fuel is reduced, in the cylinders of the back stroke cylinder group, the period from the start of fuel injection to the combustion of the fuel becomes longer, and the injection A large amount of the deposited fuel adheres to the inner wall of the intake passage. When a large amount of fuel adheres to the inner wall of the intake passage, the fuel remains attached to the inner wall when the fuel is burned in the combustion chamber later. The amount is reduced. As a result, the combustion of fuel in the cylinders of the reverse stroke cylinder group is not performed satisfactorily, thereby deteriorating the startability of the internal combustion engine.

  The present invention has been made in view of such circumstances, and the object thereof is good combustion of the fuel in the cylinders of the back stroke cylinder group after the start of the engine in a situation where the volatility of the fuel is reduced. It is an object of the present invention to provide a fuel injection control device for an internal combustion engine that can prevent the startability of the internal combustion engine from being deteriorated due to the failure of the operation.

In the following, means for achieving the above object and its effects are described.
In order to achieve the above object, the invention according to claim 1 is applied to an internal combustion engine provided with a fuel injection valve for injecting fuel from the intake passage toward the combustion chamber for each cylinder, and is necessary for starting the engine. The fuel injection amount is calculated as a starting injection amount command value, and after the crank angle is determined by cranking for engine starting, the fuel injection valve is driven and controlled in each cylinder, and the starting injection amount command value In the fuel injection control device for an internal combustion engine that injects an amount of fuel corresponding to the above, each cylinder of the internal combustion engine has the start-time injection amount command value before the first valve opening period of the first intake valve after the determination of the crank angle. Corresponding to the starting injection amount command value by the first half of the valve opening period of the first intake valve after the determination of the crank angle. After the crank angle is determined, the cylinders of the front stroke cylinder group are separated at the start of the intake valve by the first half of the valve opening period after the crank angle is determined. The fuel injection is started so that the fuel injection of the amount corresponding to the injection amount command value is completed, and the cylinders of the front stroke cylinder group, which have the same piston position as the cylinders of the reverse stroke cylinder group, are used. The amount of fuel injection corresponding to the start-time injection amount command value is started at the same timing as the fuel injection, and the start-time injection amount command value used for the fuel injection in the cylinders of the reverse stroke cylinder group is the above table. The gist of the invention is that a value that is increased and corrected so as to be a value that is larger than the starting injection amount command value used for fuel injection in the cylinders of the stroke cylinder group.

  According to the above configuration, after cranking is started and the crank angle is determined, cylinders having the same piston position in the front stroke cylinder group and the back stroke cylinder group are grouped together, and the cylinders in the same group are simultaneously Group injection for starting injection of an amount of fuel corresponding to the starting injection amount command value is performed. In the fuel injection by the group injection in the cylinders of the back stroke cylinder group, the start injection amount command value is larger than the start injection amount command value for the fuel injection by the group injection in the front stroke cylinder group. The value corrected to increase is used. For this reason, the fuel injection by the group injection in the cylinders of the reverse stroke cylinder group is performed more (longer) than the fuel injection by the group injection in the front stroke cylinder.

  By correcting the amount of fuel injection in the cylinders of the back stroke cylinder group in this way, even if the fuel injected in the cylinder adheres to the inner wall of the intake passage, etc., the fuel will be burned later in the combustion chamber It is possible to suppress a reduction in the amount of fuel present in the combustion chamber. Therefore, combustion occurs in the cylinders of the back stroke cylinder group after the start of the engine under circumstances where the volatility of the fuel decreases, such as when the engine temperature is extremely low or when a mixed fuel of gasoline and alcohol is used as the fuel. It is possible to suppress the deterioration of the startability of the internal combustion engine due to the fact that the combustion of the fuel in the cylinder is not performed satisfactorily due to the decrease in the amount of fuel present in the room.

  According to a second aspect of the present invention, in the first aspect of the invention, the increase correction of the start-time injection amount command value in the cylinders of the reverse stroke cylinder group is an increase correction value for the calculated start-time injection amount command value. The increase correction value is gradually increased as the alcohol concentration in the fuel becomes a higher value.

  According to the above configuration, after cranking is started and the crank angle is determined, fuel injection by the group injection in the cylinders of the back stroke cylinder group is performed, and the fuel injection amount increase correction at that time Is gradually increased as the alcohol concentration in the fuel increases. The higher the alcohol concentration in the fuel, the lower the fuel volatility and the more fuel adheres to the inner wall of the intake passage and so on when fuel injection is performed by the above group injection in the cylinders of the back stroke cylinder group. Therefore, when the combustion of the fuel is to be executed later in the combustion chamber, the fuel existing in the combustion chamber tends to decrease. However, the higher the alcohol concentration, the greater the correction of the fuel injection amount in the group injection in the cylinders of the back stroke cylinder group, so that after the group injection is performed, the fuel combustion in the combustion chamber is reduced. When trying to execute, it becomes possible to accurately suppress the reduction of the fuel existing in the combustion chamber regardless of whether the alcohol concentration in the fuel is high or low.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, the increase correction of the start-time injection amount command value in the cylinders of the reverse stroke cylinder group is an increase correction for the calculated start-time injection amount command value. This is realized by adding a correction for the value, and the increase correction value is gradually increased as the engine temperature decreases.

  According to the above configuration, after cranking is started and the crank angle is determined, fuel injection is performed by the group injection in the cylinders of the back stroke cylinder group, and the fuel injection fuel amount increase correction at that time is performed. Is gradually increased as the engine temperature decreases. The lower the engine temperature, the lower the volatility of the fuel when the fuel injection by the above group injection is performed in the cylinders of the back stroke cylinder group, and the more fuel adheres to the inner wall of the intake passage and so on. When attempting to perform combustion of fuel in a room, there is a tendency that less fuel is present in the combustion room. However, as the engine temperature decreases, the increase correction of the fuel injection amount in the group injection in the cylinders of the back stroke cylinder group is increased, so that the combustion of fuel in the combustion chamber is performed after the group injection is performed. When trying to do so, it is possible to accurately suppress the reduction of fuel existing in the combustion chamber regardless of the degree of decrease in the engine temperature.

  The invention according to claim 4 is the invention according to any one of claims 1 to 3, wherein the starting injection amount command value is determined based on an engine temperature and an alcohol concentration in fuel, When the engine temperature is less than the low temperature judgment value at the start of engine start, the fuel injection from the fuel injection valve is the same start timing and the same fuel injection time in all cylinders as asynchronous injection from the cranking start to the crank angle determination After the crank angle is determined, the low-temperature determination value is determined so that at least one of the front stroke cylinder group and the reverse stroke cylinder group performs fuel injection by an amount corresponding to the start injection amount command value. The gist is that it is variably set based on the alcohol concentration in the fuel so that it becomes the upper limit of the engine temperature that cannot be completed by the first half of the period.

  As the engine temperature decreases and the alcohol concentration in the fuel increases, the starting injection amount command value increases, and in the fuel injection by the above group injection in the front stroke cylinder group cylinder and the reverse stroke cylinder group cylinder, There is a high possibility that the fuel corresponding to the start injection amount command value cannot be injected by the first half of the intake valve opening period. In this way, when it is not possible to inject the amount of fuel corresponding to the start-time injection amount command value, the amount of fuel existing in the combustion chamber is reduced when the fuel is to be burned later in the combustion chamber. There is a possibility that the startability of the internal combustion engine is deteriorated because the fuel is not burned well.

  According to the above configuration, at the time of starting the engine, the engine temperature is at least one of the front stroke cylinder group and the back stroke cylinder group, and fuel injection is performed in an amount corresponding to the start injection amount command value until the first period of the intake valve opening period. When the engine temperature is less than the upper limit value of the engine temperature (below the low temperature determination value) that cannot be completed, the asynchronous injection described above is executed from the start of engine startup to the determination of the crank angle. The low temperature determination value is variably set based on the alcohol concentration in the fuel so as to be the above-described upper limit value, and is set to a larger value as the alcohol concentration becomes higher.

  If the asynchronous injection is performed before the crank angle is determined, the start of the intake valve in the group injection in the front stroke cylinder group and the reverse stroke cylinder group after the crank angle determination is started by the first half of the intake valve opening period. Even if it is not possible to inject an amount of fuel corresponding to the hourly injection amount command value, it is possible to suppress a decrease in the amount of fuel existing in the combustion chamber when the combustion of the fuel is to be executed later in the combustion chamber. Therefore, the amount of fuel present in the combustion chamber is reduced, and it is possible to suppress deterioration of the startability of the internal combustion engine due to poor combustion of the fuel.

  According to a fifth aspect of the invention, in the fourth aspect of the invention, the fuel injection time in the asynchronous injection is longer as the engine temperature at the start of engine start is lower and longer as the alcohol concentration in the fuel is higher. The gist is to be set.

  In the fuel injection by the group injection in the front stroke cylinder group cylinder or the back stroke cylinder group cylinder, the fuel corresponding to the start injection amount command value cannot be injected by the first half of the intake valve opening period. The minute increases as the starting injection amount command value increases as the engine temperature decreases or the alcohol concentration in the fuel increases. According to the above configuration, in consideration of these points, in the asynchronous injection performed before the determination of the crank angle, the fuel injection time is lengthened as the engine temperature at the start of the engine decreases and the alcohol concentration in the fuel increases. The Therefore, in the fuel injection by the group injection in the cylinders of the front stroke cylinder group and the back stroke cylinder group after the crank angle determination, an amount of fuel corresponding to the starting injection amount command value is injected as described above. Even if it is not possible, it is possible to accurately suppress the amount of fuel existing in the combustion chamber from decreasing when the combustion of the fuel is performed later in the combustion chamber by the asynchronous injection before the crank angle is determined. Therefore, the amount of fuel existing in the combustion chamber is reduced, and it is possible to more accurately suppress the deterioration of the startability of the internal combustion engine because the fuel is not burned well.

  Hereinafter, an embodiment in which the present invention is embodied in a fuel injection control device for an automotive V-type 8-cylinder engine in which a mixed fuel of gasoline and alcohol is used as fuel will be described with reference to FIGS. To do.

  In the engine 1 shown in FIG. 1, air is sucked into the combustion chamber 2 from the intake passage 3 connected to the combustion chamber 2 of each cylinder, and from the intake passage 3 by the fuel injection valve 4 provided for each cylinder. Fuel is injected toward the combustion chamber 2, and the fuel and air are supplied to the combustion chamber 2. The fuel injection valve 4 is connected to a delivery pipe 11 into which fuel stored in a fuel tank 9 is fed through the drive of a feed pump 10, and receives supply of fuel from the delivery pipe 11.

  When air and fuel are sucked into the combustion chamber 2 of each cylinder in the engine 1 as described above, an air-fuel mixture composed of the air and fuel is formed in the combustion chamber 2, and an ignition plug 5 is formed against the air-fuel mixture. Ignition is performed. When the air-fuel mixture is ignited in this way, the air-fuel mixture burns, the piston 6 reciprocates, and the crankshaft 7 that is the output shaft of the engine 1 rotates. On the other hand, the air-fuel mixture burned in the combustion chamber 2 is sent out from the combustion chamber 2 to the exhaust passage 8 as exhaust. The crankshaft 7 is connected to a starter 12 that forcibly rotates (cranks) the shaft 7 when the engine 1 is started.

  The combustion chamber 2 and the intake passage 3 are communicated and cut off by the opening / closing operation of the intake valve 13, and the combustion chamber 2 and the exhaust passage 8 are communicated and cut off by the opening / closing drive of the exhaust valve 14. The intake valve 13 is opened and closed in the intake stroke of the cylinder in which the intake valve 13 is provided through the rotation of the intake camshaft 18 to which the rotation from the crankshaft 7 is transmitted. Further, the exhaust valve 14 is opened and closed in the exhaust stroke of the cylinder provided with the exhaust valve 14 through the rotation of the exhaust camshaft 19 to which the rotation from the crankshaft 7 is transmitted.

  An automobile equipped with the engine 1 is provided with an electronic control device 21 that executes various controls related to the engine 1 such as fuel injection amount control. This electronic control device 21 includes a CPU that executes various arithmetic processes related to the above control, a ROM that stores programs and data necessary for the control, a RAM that temporarily stores CPU calculation results, and the like. An input / output port for inputting / outputting signals is provided.

Various sensors shown below are connected to the input port of the electronic control unit 21.
A water temperature sensor 15 that detects the cooling water temperature of the engine 1.
An air-fuel ratio sensor 17 that outputs a signal corresponding to the oxygen concentration in the exhaust gas.

A cam position sensor 22 that outputs a signal corresponding to the rotational position of the shaft 18 in response to the rotation of the intake camshaft 18 of the engine 1.
A crank position sensor 34 that outputs a signal corresponding to the rotation of the crankshaft 7 and is used for calculation of the engine rotation speed or the like.

  An ignition switch 35 that is switched to one of four switching positions such as “off”, “accessory”, “on”, and “start” by the driver of the automobile and outputs a signal corresponding to the current switching position.

A fuel pressure sensor 36 that detects the pressure of fuel in the delivery pipe 11.
On the other hand, to the output port of the electronic control device 21, a drive circuit such as the fuel injection valve 4, the spark plug 5, and the starter 12 is connected.

  Then, the electronic control unit 21 grasps the engine operating state based on the detection signals input from the various sensors, and outputs command signals to various driving circuits connected to the output port according to the engine operating state. Various controls in the engine 1 such as fuel injection control, ignition timing control, and starter 12 drive control are thus performed through the electronic control unit 21.

  Next, various controls related to the start of the engine 1 will be described with reference to the timing chart of FIG. This figure shows the opening / closing mode, the fuel injection mode, and the ignition mode of the intake valve 13 in each cylinder (# 1 to # 8) with respect to the change of the crank angle when the engine 1 is started.

  When the engine 1 is started, when the ignition switch 35 is switched to the “on” position at the time of starting, the fuel injection amount required for the start is calculated as a start-time injection amount command value. When the ignition switch 35 is switched from “ON” to “START”, the starter 12 is driven to start cranking for starting the engine (timing T1). When cranking is started in this way, the crank angle is determined based on signals from the cam position sensor 22 and the crank position sensor 34 that are output as the engine rotates (timing T2).

  After the crank angle is determined, fuel corresponding to the start injection amount command value is injected from the intake passage 3 toward the combustion chamber 2 through drive control of the fuel injection valve 4 in each cylinder. Regarding such fuel injection, based on the fuel pressure in the delivery pipe 11 that supplies fuel to the fuel injection valve 4, the time required to inject an amount of fuel corresponding to the start-time injection amount command value at that fuel pressure. Is calculated as the fuel injection time, and the fuel injection valve 4 is opened for a time corresponding to the fuel injection time.

  Then, when fuel injection is performed in an amount corresponding to the start-time injection amount command value and combustion based on ignition of the air-fuel mixture in the combustion chamber 2 by the ignition plug 5 is performed, the engine speed increases accordingly. Thus, the autonomous operation of the engine 1 is started. After fuel injection of an amount corresponding to the start-time injection amount command value is performed in all cylinders, fuel injection amount control and fuel during normal engine operation based on engine operating conditions such as engine speed and engine load are performed. Injection timing control is performed.

  Each cylinder (# 1 to # 8) of the engine 1 is divided into two cylinder groups, a front stroke cylinder group and a back stroke cylinder group. Here, the front stroke cylinder group refers to performing fuel injection in an amount corresponding to the starting injection amount command value by the first half of the valve opening period of the first intake valve 13 after the determination of the crank angle (after T2). This is a cylinder group consisting of possible cylinders (# 6, # 5, # 4, # 2 in this example). The reverse stroke cylinder group is a cylinder incapable of performing fuel injection in an amount corresponding to the start injection amount command value by the first valve opening period of the first intake valve 13 after the determination of the crank angle. (In this example, it is a cylinder group consisting of # 1, # 8, # 7, # 3).

  By the way, after the timing T2, an amount of fuel corresponding to the starting injection amount command value is efficiently supplied to the combustion chamber 2 of each cylinder so that the engine 1 can be started well by the combustion of the fuel (air mixture). In order to achieve this, it is conceivable that fuel injection of an amount corresponding to the start-time injection amount command value by the fuel injection valve 4 of each cylinder is performed by the following intake synchronous injection.

  That is, in each cylinder, fuel injection of an amount corresponding to the start-time injection amount command value from the fuel injection valve 4 in the first half of the valve opening period of the intake valve 13, in other words, the start-up time from the intake passage 3 to the combustion chamber 2 The fuel injection is started so that the fuel injection of the amount corresponding to the injection amount command value is completed. More specifically, with respect to the previous period of the valve opening period of the intake valve 13, at a timing that goes back by the fuel injection time, which is the time required to execute the fuel injection of the amount corresponding to the start injection amount command value, The fuel injection is started. By performing the fuel injection in this way, it is possible to efficiently supply the fuel to the combustion chamber 2 and improve the start of the engine 1 by the combustion of the fuel. When the intake-synchronized injection is executed, in the cylinders of the reverse stroke cylinder group, an amount of fuel injection corresponding to the start-time injection amount command value by the first half of the valve opening period after the start of engine start in the intake valve 13 is started. The fuel injection is started so as to be completed.

  When intake synchronous injection for engine start is performed as described above, as shown in FIG. 3, first, fuel injection is started in order in each cylinder of the front stroke cylinder group (after timing T4), and then the reverse stroke. Fuel injection is sequentially started in each cylinder of the cylinder group. For this reason, when the engine speed rapidly increases with combustion of fuel in the cylinders of the front stroke cylinder group (timing T5), the start timing of fuel injection in the cylinders of the back stroke cylinder group as the engine speed rapidly increases. From this time, the time from the intake valve 13 to the first half of the valve opening period is shortened, so that there is a possibility that the fuel corresponding to the starting injection amount command value cannot be injected. Thus, if it becomes impossible to inject the fuel corresponding to the starting injection amount command value in the cylinders of the back stroke cylinder group, it becomes difficult to perform the combustion of the fuel well in the combustion chamber 2. The startability of 1 may deteriorate.

  In order to cope with this, after cranking is started and the crank angle is determined (after T2 in FIG. 2), it is considered to perform group injection as shown in FIG. 2 instead of the intake synchronous injection described above. It is done. Specifically, in the cylinders of the front stroke cylinder group, fuel injection is performed in an amount corresponding to the start-time injection amount command value in the same manner as the intake-synchronized injection, and the start timing of the fuel injection is also the intake-synchronized injection. The timing is the same as the injection. Further, in the cylinders of the reverse stroke cylinder group, the cylinders of the front stroke cylinder group in which the start timing and the injection time of the fuel corresponding to the starting injection amount command value are the same piston position as the piston position of the cylinder This is the same as the fuel injection start timing and injection time.

  Therefore, in the group injection, cylinders having the same piston position in the front stroke cylinder group and the reverse stroke cylinder group form one group, and in the cylinders of the same group, an amount of fuel corresponding to the start injection amount command value is obtained. Injection is performed at the same start timing and injection time. In the example of FIG. 2, as a group for performing group injection, each cylinder (# 1 to # 8) is a group of cylinder # 1 and cylinder # 6, and a group of cylinder # 8 and cylinder # 5. Are grouped into a group of cylinder # 7 and cylinder # 4 and a group of cylinder # 3 and cylinder # 2. By performing fuel injection (group injection) for each group described above, fuel injection in an amount corresponding to the start-time injection amount command value is performed earlier in the cylinders of the reverse stroke cylinder group than the intake synchronous injection. become. For this reason, when the engine rotation speed suddenly increases due to the combustion of fuel in the cylinders of the front stroke cylinder group after the start of the engine start, the intake valve 13 is opened in the first half of the valve opening period (second This prevents the amount of fuel corresponding to the start-time injection amount command value from being completely injected by the first half of the valve opening period).

  However, if the above-described group injection is performed when the volatility of the fuel is low, such as when the engine temperature of the engine 1 is extremely low or the alcohol concentration in the fuel is high, the back stroke cylinder group In the cylinder, the period from the start of fuel injection to the combustion of the fuel becomes longer, and a lot of injected fuel adheres to the inner wall of the intake passage 3 and the like. When a large amount of fuel adheres to the inner wall or the like of the intake passage 3 as described above, the second ignition after the crank angle determination is performed when the combustion of the fuel in the combustion chamber 2 is to be executed later. ), The amount of fuel existing in the combustion chamber 2 is reduced because the fuel remains attached to the inner wall or the like. As a result, the combustion of fuel in the cylinders of the back stroke cylinder group is not performed satisfactorily, thereby deteriorating the startability of the engine 1.

Next, countermeasures of the present embodiment for suppressing the occurrence of the above-described problems will be described with reference to FIGS.
In the present embodiment, as a countermeasure against the above-described problem, the starting injection amount command value used for fuel injection in the cylinders of the reverse stroke cylinder group in the group injection is used for fuel injection in the cylinders of the front stroke cylinder group. A value that is increased and corrected so as to be larger than the starting injection amount command value is used. Specifically, the starting injection amount command value used for fuel injection in the cylinders of the front stroke cylinder group is “Q1”, and the starting injection amount command value used for fuel injection in the cylinders of the back stroke cylinder group is Assuming “Q2”, the command values Q1 and Q2 are calculated as follows, including the increase correction.

  The starting injection amount command value Q1 used for fuel injection in the cylinders of the front stroke cylinder group is calculated based on the coolant temperature (corresponding to the engine temperature of the engine 1) and the alcohol concentration in the fuel at the start of the engine 1. The As for the alcohol concentration in the fuel, it is conceivable to use a value estimated and stored based on a signal output from the air-fuel ratio sensor 17 during engine operation immediately after refueling. Further, an alcohol concentration sensor may be provided in a fuel tank or the like, the alcohol concentration in the fuel may be obtained based on a signal from the sensor, and the alcohol concentration may be used.

  As for the fuel injected from the fuel injection valve 4, the lower the coolant temperature and the higher the alcohol concentration in the fuel, the lower the volatility and the easier it is to adhere to the inner wall of the intake passage 3. For this reason, the lower the coolant temperature and the higher the alcohol concentration in the fuel, the more the fuel corresponding to the start-time injection amount command value Q1 is injected into the combustion chamber 2 in the cylinders of the front stroke cylinder group. There is a tendency for the amount of fuel that enters to decrease. Based on this tendency, the calculated start-time injection amount command value Q1 increases as the coolant temperature decreases so that the amount of fuel entering the combustion chamber 2 becomes a value necessary for starting the engine 1. In addition, the higher the alcohol concentration in the fuel, the higher the value.

  On the other hand, the starting injection amount command value Q2 used for fuel injection in the cylinders of the reverse stroke cylinder group is a value obtained by multiplying the starting injection amount command value Q1 calculated as described above by an increase correction coefficient K. Q1 · K ”is used. In other words, the starting injection amount command value Q2 is calculated by multiplying the starting injection amount command value Q1 by the increase correction coefficient K. Therefore, the starting injection amount command value Q2 is a value that has been increased and corrected so as to be larger than the starting injection amount command value Q1 by an amount corresponding to the increase correction coefficient K (increase correction value). Become. As shown in FIG. 4, the increase correction coefficient K is gradually larger than “1.0” as the cooling water temperature at the start of engine start decreases and the alcohol concentration in the fuel increases. Calculated to be a value.

  FIG. 5 is a timing chart showing the fuel injection mode and the like in the group injection with respect to the change in the crank angle after the start of the engine start when the start time injection amount command values Q1 and Q2 are calculated as described above. Incidentally, the changing speed of the crank angle in the figure is equal to the changing speed of the crank angle in FIG.

  As can be seen from FIG. 5, the fuel injection by the group injection in the cylinders (# 1, # 8, # 7, # 3) of the back stroke cylinder group is the cylinders (# 6, # 5, # of the front stroke cylinder group). Compared with the fuel injection by the group injection in 4, # 2), the fuel injection is performed more (longer) by the amount indicated by hatching in the drawing. This is because the startup injection amount command value Q2 is a value that has been increased and corrected so as to be larger than the startup injection amount command value Q1 by the amount corresponding to the increase correction coefficient K. By correcting the fuel injection amount in the cylinders of the reverse stroke cylinder group in this way, even if the fuel injected in the cylinder adheres to the inner wall of the intake passage 3 or the like, the combustion of the fuel in the combustion chamber 2 is performed later. It is possible to suppress the amount of fuel present in the combustion chamber 2 from being reduced when the control is executed (in the example shown in the figure, when the second ignition after the crank angle is determined). Therefore, the amount of fuel present in the combustion chamber 2 is small as described above in a situation where the volatility of the fuel decreases, such as when the cooling water temperature (engine temperature) is extremely low or the alcohol concentration in the fuel is high. As a result, the combustion of fuel in the cylinders of the back stroke cylinder group is not performed satisfactorily, thereby preventing the startability of the engine 1 from deteriorating.

  With respect to the increase correction coefficient K, the fuel in the combustion chamber 2 is intended to be burned after fuel injection of an amount corresponding to the start-time injection amount command value Q2 is performed in the cylinders of the reverse stroke cylinder group. In this case, the amount of fuel present in the combustion chamber 2 is calculated based on the coolant temperature and the alcohol concentration so that the amount required for starting the engine 1 is not insufficient. That is, the starting injection amount command value Q2 is calculated based on the starting injection cooling water temperature and the alcohol concentration so that the fuel amount in the combustion chamber 2 does not become insufficient.

  Next, in the above-described group injection, when the amount of fuel corresponding to the start-time injection amount command value Q1 cannot be injected in the front stroke cylinder group by the first half of the valve opening period of the intake valve 13, the back stroke cylinder group A countermeasure for a case in which the amount of fuel corresponding to the start-time injection amount command value Q2 cannot be injected by the first half of the valve opening period of the intake valve 13 will be described with reference to FIGS.

  The starting injection amount command values Q1 and Q2 increase as the cooling water temperature (corresponding to the engine temperature of the engine 1) at the start of engine startup decreases and the alcohol concentration in the fuel increases. For this reason, as the cooling water temperature decreases and the alcohol concentration increases, the time required for the fuel injection by the group injection in the cylinders of the front stroke cylinder group and the cylinders of the back stroke cylinder group becomes longer. Therefore, there is a high possibility that the fuel corresponding to the start-time injection amount command values Q1 and Q2 cannot be injected by the first half of the valve opening period of the intake valve 13.

  FIG. 6 shows an injection-time injection amount command in the fuel injection by the group injection in the cylinders of the reverse stroke cylinder group by the first valve opening period of the intake valve 13 (the second valve opening period first after the start of the engine 1). An example in which the amount of fuel corresponding to the value Q2 cannot be injected is shown. When the fuel corresponding to the starting injection amount command value Q2 cannot be injected in this way, when the fuel is to be burned later in the combustion chamber 2 (in the example shown in the figure, the two after the crank angle determination). When the second ignition is performed), the amount of fuel present in the combustion chamber 2 is reduced, and the fuel is not combusted satisfactorily, so that the startability of the engine 1 may be deteriorated.

  When such a situation may occur, in the present embodiment, fuel injection from the fuel injection valve 4 is the same start timing in all cylinders as asynchronous injection from the cranking start (T1) to the crank angle determination (T2). (Timing T6) and the same fuel injection time T is executed. Specifically, when the cooling water temperature is lower than a low temperature determination value that is variably set according to the alcohol concentration in the fuel at the start of engine start, it is determined that the above-described situation may occur, and the asynchronous injection is started from the start of cranking. The process is executed until the crank angle is determined (T1 to T2).

  By performing the asynchronous injection in this manner, even if the amount of fuel corresponding to the start-time injection amount command value cannot be injected by the group injection by the first half of the valve opening period of the intake valve 13, It is possible to suppress a reduction in the amount of fuel existing in the combustion chamber 2 when attempting to perform fuel combustion in the combustion chamber 2. Therefore, the amount of fuel present in the combustion chamber 2 is reduced, and it is possible to suppress the startability of the engine 1 from being deteriorated due to poor combustion of the fuel.

Here, the setting aspect of the said low-temperature determination value used when determining whether to perform the said asynchronous injection is demonstrated with reference to FIG.7 and FIG.8.
In FIG. 7, the solid line shows the transition of the starting injection amount command value Q1 in the cylinders of the front stroke cylinder group with respect to changes in the coolant temperature of the engine 1 and the alcohol concentration in the fuel, and the broken line shows the group injection in the same cylinder. The upper limit value of the fuel injection amount that can be injected by the first half of the valve opening period of the intake valve 13 is shown. Then, the water temperature thw1 corresponding to the intersection of the solid line and the broken line in the figure is equal to the amount of fuel corresponding to the start-time injection amount command value Q1 in the front stroke cylinder group until the first valve opening period of the intake valve 13 by the group injection. This is the lower limit value of the coolant temperature of the engine 1 that can complete the injection. The water temperature thw1 becomes higher as the alcohol concentration in the fuel becomes higher, as is apparent from the figure. Therefore, the water temperature thw1 can be calculated based on the alcohol concentration and the starting injection amount command value Q1 in consideration of these characteristics. Is possible.

  In FIG. 8, the solid line shows the transition of the starting injection amount command value Q2 in the cylinders of the reverse stroke cylinder group with respect to changes in the coolant temperature of the engine 1 and the alcohol concentration in the fuel, and the broken line shows the group injection in the cylinder. The upper limit value of the fuel injection amount that can be injected by the first half of the valve opening period of the intake valve 13 is shown. Then, the water temperature thw2 corresponding to the intersection of the solid line and the broken line in the figure is equal to the amount of fuel corresponding to the starting injection amount command value Q2 in the reverse stroke cylinder group until the first period of the valve opening period of the intake valve 13 by the group injection. This is the lower limit value of the coolant temperature of the engine 1 that can complete the injection. The water temperature thw2 becomes higher as the alcohol concentration in the fuel becomes higher, as is apparent from the figure. Therefore, the water temperature thw2 can be calculated based on the alcohol concentration and the starting injection amount command value Q2 in consideration of such characteristics. Is possible.

  When setting the low-temperature determination value described above, first, the water temperature thw1 (FIG. 7) is calculated based on the starting injection amount command value Q1 and the alcohol concentration in the fuel, and the water temperature thw2 (FIG. 8) is It is calculated based on the injection amount command value Q2 and the alcohol concentration in the fuel. Note that the water temperatures thw1 and thw2 may be calculated with reference to a map determined in advance by an experiment or the like, or may be performed using a calculation formula determined by an experiment or the like. Regarding the water temperatures thw1 and thw2 calculated in this way, both values become higher as the alcohol concentration in the fuel becomes higher. The larger one of the calculated water temperature thw1 and water temperature thw2 is set as the low temperature determination value.

  Setting the low temperature determination value in this way means that after determining the crank angle at the time of engine start, at least one of the front stroke cylinder group and the back stroke cylinder group, the amount of fuel corresponding to the start injection quantity command value is This means that the low temperature determination value is set to the upper limit value of the coolant temperature (corresponding to the engine temperature of the engine 1) that cannot be completed by the first half of the valve opening period of the intake valve 13 due to group injection. The low-temperature determination value set in this way also becomes higher as the alcohol concentration in the fuel is higher, like the water temperatures thw1 and thw2.

  Next, a start-up injection control setting routine for the procedure for setting the fuel injection time T in the asynchronous injection at the time of engine start and the procedure for setting the start-time injection amount command values Q1, Q2 used for the group injection. This will be described with reference to the flowchart of FIG. This starting injection control setting routine is executed when the ignition switch 35 is switched from “OFF” to “ON” through the electronic control unit 21.

  In this routine, a process for setting the flag F1 for determining whether or not the asynchronous injection is performed after the cranking is started and for setting the fuel injection time T for the asynchronous injection (S101 to S104). Is executed. In this series of processes, first, it is determined whether or not the coolant temperature of the engine 1 (corresponding to the engine temperature of the engine 1) is less than the low temperature determination value (S101). If the determination is affirmative, the flag F1 is set to “0 (execution)” (S102), and the fuel injection time T in the asynchronous injection is based on the cooling water temperature at the start of engine start and the alcohol concentration in the fuel. The fuel injection time T thus set is longer as the cooling water temperature is lower and is longer as the alcohol concentration is higher, whereas when a negative determination is made in step S101 The flag F1 is set to “0 (non-execution)” (S104).

  Thereafter, processing (S105 to S107) for setting the starting injection amount command values Q1 and Q2 in the group injection performed after cranking is started and the crank angle is determined is executed. Specifically, a starting injection amount command value Q1 is calculated based on the coolant temperature at the start of engine starting and the alcohol concentration in the fuel (S105), and the starting injection amount command value Q1 is the front stroke cylinder in the group injection. It is set as a command value for the fuel injection amount in the cylinders of the group. Subsequently, an increase correction coefficient K (see FIG. 3) is calculated based on the cooling water temperature and the alcohol concentration (S106). Then, by multiplying the start-up injection amount command value Q1 by the increase correction coefficient K, a value (Q1 · K) after the multiplication is calculated as a start-up injection amount command value Q2 (S107). The injection amount command value Q2 is set as a command value for the fuel injection amount in the cylinders of the reverse stroke cylinder group in the group injection.

  Next, the execution procedure of the asynchronous injection and the group injection will be described with reference to the flowchart of FIG. 10 showing the start-time injection control execution routine. The start-up injection control execution routine is periodically executed through the electronic control unit 21 by, for example, an angle interruption for each predetermined crank angle.

  In this routine, processing (S201 to S203) for executing the asynchronous injection is executed. In this series of processing, it is first determined whether or not the ignition switch 35 has been switched to the “start” position (S201). If it is a stroke determination here, it is determined that it is at the start of cranking, and the flag F1 for determining whether or not to perform the asynchronous injection is “1 (execution)” after the cranking starts. (S202: YES), fuel injection is performed for the fuel injection time T after cranking starts in all cylinders as the asynchronous injection (S203). When the flag F1 is “0 (non-execution)” (S202: NO), the process of step S203 is skipped, and the asynchronous injection is not performed.

  Then, the process (S204-S207) for performing the said group injection is performed. In this series of processing, it is first determined whether or not the crank angle has been determined (S204). If the determination is affirmative, it is determined whether or not the flag F2 for determining whether or not the affirmative determination is made for the first time after the start of engine start is “0 (first time)” ( S205). If the flag F2 is “0 (first time)”, fuel injection of the amount corresponding to the start-time injection amount command value Q1 is performed in the cylinders of the front positive cylinder group as the group injection, and the reverse positive cylinder group The fuel is injected in an amount corresponding to the starting injection amount command value Q2 in the cylinder (S206).

  After the group injection is performed, the flag F2 is set to “1 (non-first time)” (S207). Therefore, when the process proceeds to the determination process in step S205 next time, a negative determination is made in the determination process, and the process in step S206 is skipped, so that the group injection is not performed. The flag F2 is reset to “0” when the engine 1 is stopped.

According to the embodiment described in detail above, the following effects can be obtained.
(1) After cranking is started and the crank angle is determined, the group injection is performed. In the fuel injection by the group injection in the cylinders of the reverse stroke cylinder group, the injection amount command value Q2 at the start is expressed as A value that has been corrected to increase to a value that is larger than the starting injection amount command value Q1 for fuel injection by the same group injection in the stroke cylinder group is used. For this reason, the fuel injection by the group injection in the cylinders of the reverse stroke cylinder group is performed more (longer) than the fuel injection by the group injection in the front stroke cylinder. By correcting the fuel injection amount in the cylinders of the reverse stroke cylinder group in this way, even if the fuel injected in the cylinder adheres to the inner wall of the intake passage 3 or the like, the combustion of the fuel in the combustion chamber 2 is performed later. It is possible to suppress a reduction in the amount of fuel present in the combustion chamber 2 when trying to execute. Therefore, when the cooling water temperature (corresponding to the engine temperature of the engine 1) is extremely low or the alcohol concentration in the fuel is high, the fuel exists in the combustion chamber 2 as described above in a situation where the volatility of the fuel decreases. Due to the reduction in the amount of fuel, it is possible to prevent the fuel in the group injection from being burned well in the cylinders of the back stroke cylinder group. Therefore, it is possible to suppress the deterioration of the startability of the engine 1 due to the fact that the fuel in the cylinders of the reverse stroke cylinder group is not burned well.

  (2) As the alcohol concentration in the fuel is higher and the cooling water temperature of the engine 1 is lower, when the fuel injection by the group injection is performed in the cylinders of the back stroke cylinder group, the volatility of the fuel decreases and the intake passage There is a tendency that the amount of fuel adhering to the inner wall of the combustion chamber 3 increases and the amount of fuel existing in the combustion chamber 2 decreases when the combustion of the fuel is attempted in the combustion chamber 2 later. However, regarding the increase correction of the fuel injection amount (startup injection amount command value Q2) in the cylinders of the reverse stroke cylinder group in the group injection, the higher the alcohol concentration in the fuel is, the more the cooling water temperature of the engine 1 is increased. As the value decreases, it is gradually increased. Therefore, when it is attempted to execute the combustion of the fuel in the combustion chamber 2 in the reverse stroke cylinder group after the group injection has been performed, the fact that the amount of fuel existing in the combustion chamber 2 decreases, the alcohol concentration in the fuel Regardless of whether the engine is dark or thin, and regardless of the degree of decrease in the coolant temperature of the engine 1, it can be accurately controlled.

  (3) The starting injection amount command values Q1 and Q2 used for the group injection increase as the cooling water temperature decreases and the alcohol concentration in the fuel increases. As a result, in the fuel injection by the group injection in the front stroke cylinder group and the reverse stroke cylinder group, the amounts corresponding to the start-time injection amount command values Q1 and Q2 by the first half of the valve opening period of the intake valve 13 There is a high possibility that the fuel cannot be injected. In this way, when it is not possible to inject the fuel corresponding to the start-time injection amount command values Q1 and Q2, the fuel existing in the combustion chamber 2 when the fuel is to be burned in the combustion chamber 2 later. There is a risk that the startability of the engine 1 may be deteriorated because the amount of the fuel is reduced and the fuel is not combusted satisfactorily. In order to cope with such a problem, when there is a possibility that the above situation may occur, the fuel injection from the fuel injection valve 4 is performed at the same start timing and the same in all the cylinders from the start of the engine start to the determination of the crank angle. Asynchronous injection is performed for the fuel injection time T only.

  More specifically, at the time of starting the engine, the cooling water temperature is at least one of the front stroke cylinder group and the reverse stroke cylinder group, and fuel injection of the amount corresponding to the start injection amount command value is performed by the first half of the valve opening period of the intake valve 13. When it is less than the upper limit value of the cooling water temperature that cannot be completed (below the low temperature determination value), it is determined that the above situation may occur. The low-temperature determination value is variably set according to the alcohol concentration so that the higher the alcohol concentration in the fuel, the higher the value. When the coolant temperature is lower than the low temperature determination value at the start of engine start, the asynchronous injection is executed from the start of cranking to the crank angle determination.

  By performing the asynchronous injection in this manner, even if the amount of fuel corresponding to the start-time injection amount command value cannot be injected by the group injection by the first half of the valve opening period of the intake valve 13, It is possible to suppress a reduction in the amount of fuel existing in the combustion chamber 2 when attempting to perform fuel combustion in the combustion chamber 2. Therefore, the amount of fuel present in the combustion chamber 2 is reduced, and it is possible to suppress the startability of the engine 1 from being deteriorated due to poor combustion of the fuel.

  (4) In the fuel injection by the group injection in the front stroke cylinder group and the back stroke cylinder group, the amount corresponding to the start-time injection amount command values Q1 and Q2 by the first half of the valve opening period of the intake valve 13 The amount of fuel that cannot be injected increases as the starting injection amount command values Q1 and Q2 increase as the coolant temperature decreases and the alcohol concentration in the fuel increases. Considering this, in the asynchronous injection performed before the crank angle is determined, the fuel injection is performed as the coolant temperature at the start of the engine start (corresponding to the engine temperature of the engine 1) decreases and the alcohol concentration in the fuel increases. Time T is lengthened. For this reason, in the fuel injection by the group injection in the cylinders of the front stroke cylinder group and the cylinders of the back stroke cylinder group, the amount of fuel corresponding to the start-time injection amount command values Q1 and Q2 cannot be injected as described above. However, when the fuel is burned in the combustion chamber 2 later, the amount of fuel existing in the combustion chamber 2 can be accurately suppressed by the asynchronous injection. Therefore, the amount of fuel present in the combustion chamber 2 is reduced, and it is possible to more accurately suppress the deterioration of the startability of the engine 1 due to poor combustion of the fuel.

In addition, the said embodiment can also be changed as follows, for example.
-Regarding the fuel injection time T in the asynchronous injection, a fixed value determined in advance through experiments or the like may be adopted. Even in this case, the effects (1) to (3) can be obtained.

-It is not always necessary to execute the asynchronous injection. Even in this case, the effects (1) and (2) can be obtained.
In the above-described group injection, the magnitude of the fuel injection amount increase correction in the cylinders of the back stroke cylinder group is variable based on the cooling water temperature of the engine 1 and the alcohol concentration in the fuel. It is good also as a variable based only on either one.

  -Regarding the increase correction of the fuel injection amount in the cylinders of the reverse stroke cylinder group in the above group injection, the variable mode based on the cooling water temperature can be changed stepwise in two or three steps, or the alcohol concentration can be changed. It is also possible to change the variable mode based on multi-steps such as two steps or three steps.

  -Regarding the magnitude of the fuel injection amount increase correction in the cylinders of the reverse stroke cylinder group in the above-described group injection, it is not always necessary to make it variable according to the cooling water temperature or the alcohol concentration, and is optimally determined in advance through experiments or the like. You may fix to a magnitude | size.

  The present invention may be applied to an engine that uses only gasoline as fuel.

BRIEF DESCRIPTION OF THE DRAWINGS Schematic which shows the whole engine with which the fuel-injection control apparatus of this embodiment is applied. The timing chart which showed the opening-and-closing mode of the intake valve in each cylinder (# 1- # 8) with respect to the change of the crank angle at the time of engine starting, a fuel injection mode, and an ignition mode. The time chart which shows the change of the engine rotational speed with respect to time passage after an engine start start. The graph which shows transition with respect to the change of the cooling water temperature of the engine of the increase correction coefficient K used by the group injection after an engine start start, and the alcohol concentration in a fuel. The timing chart which showed the opening-and-closing mode of the intake valve in each cylinder (# 1- # 8) with respect to the change of the crank angle at the time of engine starting, a fuel injection mode, and an ignition mode. The timing chart which showed the opening-and-closing mode of the intake valve in each cylinder (# 1- # 8) with respect to the change of the crank angle at the time of engine starting, a fuel injection mode, and an ignition mode. The graph which shows transition with respect to the change of the cooling water temperature and alcohol concentration of the fuel injection amount command value in the cylinder of the front stroke cylinder group in the said group injection. The graph which shows transition with respect to the change of the cooling water temperature and alcohol concentration of the fuel injection amount command value in the cylinder of the back stroke cylinder group in the said group injection. The flowchart which shows the setting procedure of the fuel injection time in the asynchronous injection at the time of engine starting, and the setting procedure of the injection amount command value at the time of start used for the said group injection. The flowchart which shows the execution procedure of the said asynchronous injection at the time of engine starting, and the said group injection.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Engine, 2 ... Combustion chamber, 3 ... Intake passage, 4 ... Fuel injection valve, 5 ... Spark plug, 6 ... Piston, 7 ... Crankshaft, 8 ... Exhaust passage, 9 ... Fuel tank, 10 ... Feed pump, 11 DESCRIPTION OF SYMBOLS ... Delivery pipe, 12 ... Starter, 13 ... Intake valve, 14 ... Exhaust valve, 15 ... Water temperature sensor, 17 ... Air-fuel ratio sensor, 18 ... Intake camshaft, 19 ... Exhaust camshaft, 21 ... Electronic control unit, 22 ... Cam Position sensor 34 ... Crank position sensor 35 ... Ignition switch 36 ... Fuel pressure sensor

Claims (5)

This is applied to an internal combustion engine provided with a fuel injection valve that injects fuel from the intake passage toward the combustion chamber for each cylinder, and calculates the fuel injection amount necessary for starting the engine as a starting injection amount command value. After the crank angle is determined by cranking for starting the engine, the fuel injection control of the internal combustion engine in which the fuel injection valve is driven and controlled in each cylinder to inject an amount of fuel corresponding to the starting injection amount command value In the device
Each cylinder of the internal combustion engine is a front stroke comprising cylinders capable of performing fuel injection in an amount corresponding to the start-time injection amount command value by the first half of the valve opening period of the first intake valve after the determination of the crank angle. Back stroke cylinder group consisting of a cylinder group and a cylinder incapable of performing fuel injection in an amount corresponding to the start-time injection amount command value by the first half of the valve opening period of the first intake valve after the determination of the crank angle Divided into
After the determination of the crank angle, in the cylinders of the front stroke cylinder group, the fuel injection is started so that the fuel injection of the amount corresponding to the start-time injection amount command value is completed by the first half of the intake valve opening period. In addition, in the cylinders in the reverse stroke cylinder group, fuel injection of an amount corresponding to the start-time injection amount command value is started at the same timing as the fuel injection in the cylinders in the front stroke cylinder group at the same piston position as the cylinders. And
The starting injection amount command value used for the fuel injection in the cylinders of the back stroke cylinder group is larger than the starting injection amount command value used for the fuel injection in the cylinders of the front stroke cylinder group. A fuel injection control device for an internal combustion engine, characterized in that a value corrected so as to increase is used. The increase correction of the starting injection amount command value in the cylinders of the reverse stroke cylinder group is realized by adding a correction corresponding to the increase correction value to the calculated starting injection amount command value, and the increase correction The fuel injection control device for an internal combustion engine according to claim 1, wherein the value is gradually increased as the alcohol concentration in the fuel becomes higher. The increase correction of the starting injection amount command value in the cylinders of the reverse stroke cylinder group is realized by adding a correction corresponding to the increase correction value to the calculated starting injection amount command value, and the increase correction The fuel injection control device for an internal combustion engine according to claim 1 or 2, wherein the value is gradually increased as the engine temperature decreases. The starting injection amount command value is determined based on the engine temperature and the alcohol concentration in the fuel,
When the engine temperature is less than the low temperature judgment value at the start of engine start, the fuel injection from the fuel injection valve is the same start timing and the same fuel injection time in all cylinders as asynchronous injection from the cranking start to the crank angle determination Just run and
After the crank angle is determined, the low temperature determination value is determined so that at least one of the front stroke cylinder group and the reverse stroke cylinder group has a fuel injection amount equal to the start injection amount command value before the intake valve opening period. The fuel injection control device for an internal combustion engine according to any one of claims 1 to 3, wherein the fuel injection control device is variably set based on an alcohol concentration in the fuel so as to be an upper limit value of the engine temperature that cannot be completed. The fuel injection control device for an internal combustion engine according to claim 4, wherein the fuel injection time in the asynchronous injection is set to be longer as the engine temperature at the start of engine start is lower and longer as the alcohol concentration in the fuel is higher.

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