JP2009299542A - Fuel supply device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress delay of first fuel injection, when cylinders in which fuel injection is performed firstly after beginning start are cylinders of a second cylinder group in an internal combustion engine after the start. <P>SOLUTION: In the internal combustion engine 31, fuel injection timings of cylinders of the first cylinder group and the cylinders of the second cylinder group are alternately set. The first cylinder group is a cylinder group in which a period of a pressure-feeding stroke of a high-pressure fuel pump 4 before the fuel injection timing is longer than a period at the pressure-feeding stroke after the timing. The second cylinder group is a cylinder group in which a period at the pressure-feeding stroke before the fuel injection timing is shorter than a period at the pressure-feeding stroke after the timing. The first fuel injection in the internal combustion engine 31 in the start is permitted at the fuel injection timing while fuel pressure is a target value or more. In the first cylinder group, the target value is set to be a first target value. In the second cylinder group, the target value is set to be a second target value smaller than the first target value. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

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

  In a cylinder-injection internal combustion engine that directly injects fuel into the combustion chamber of each cylinder, the fuel injection from the fuel injection valve can be performed against the high pressure in the combustion chamber. A fuel supply device is provided for supplying high pressure fuel to the valve.

  Such a fuel supply device includes a high-pressure fuel pump that boosts and discharges fuel pumped up from a fuel tank by a feed pump, and a delivery pipe that stores the fuel discharged from the high-pressure fuel pump and distributes it to the fuel injection valves of each cylinder. And. The high-pressure fuel pump is driven by a cam that rotates as the crankshaft of the internal combustion engine rotates, and repeats a suction stroke and a pressure-feed stroke, and discharges high-pressure fuel toward a delivery pipe during the pressure-feed stroke. . A fuel injection valve provided in each cylinder of the internal combustion engine receives fuel supplied from a delivery pipe in which high-pressure fuel discharged from the high-pressure fuel pump is stored. The fuel pressure in the delivery pipe in which the high-pressure fuel is stored is a target value that is larger than the minimum value (combustible fuel pressure) at which fuel can be properly injected from the fuel injection valve into the combustion chamber. Value (for example, about 6 MPa). Therefore, by supplying high-pressure fuel from the delivery pipe to the fuel injection valve, fuel can be injected from the fuel injection valve into the combustion chamber.

  When the internal combustion engine provided with the fuel supply device is started and the crankshaft is rotated immediately after the start of the start, the fuel pressure in the delivery pipe is changed to the target value every time the fuel injection timing of each cylinder in the engine is reached. It is determined whether or not the state has risen to a value. If the fuel pressure does not reach the target value, fuel injection from the fuel injection valve is not permitted in the cylinder that has reached the fuel injection timing at that time. On the other hand, if the fuel pressure has reached the target value, fuel injection from the fuel injection valve in the internal combustion engine is permitted, and the first fuel injection after the start of the engine is performed in the cylinder that has reached the fuel injection timing. Will be. Regarding the fuel injection from the first fuel injection valve after the start of the engine start, the fuel injection amount at that time is adjusted to a value determined by the engine temperature at the start of the engine start.

  By the way, when the high-pressure fuel pump provided in the fuel supply device performs one pumping stroke every time the fuel injection timing is reached twice when the crankshaft rotates, each cylinder of the internal combustion engine is referred to as the first cylinder group. It is divided into the second cylinder group.

  Here, the first cylinder group refers to the period of the pumping stroke of the high-pressure fuel pump between the current fuel injection timing and the previous fuel injection timing when the fuel injection timing is reached, It is a cylinder group which becomes longer than the period of the pumping stroke of the high-pressure fuel pump between the fuel injection timings. In addition, the second cylinder group means that the period of the pumping stroke of the high pressure fuel pump between the current fuel injection timing and the previous fuel injection timing when the fuel injection timing comes, The cylinder group is shorter than the period of the pressure stroke of the high-pressure fuel pump between the fuel injection timings.

  In addition, as a fuel supply apparatus provided with a high-pressure fuel pump so that each cylinder of the internal combustion engine is divided into the first cylinder group and the second cylinder group described above, for example, the one disclosed in Patent Document 1 can be cited. In the fuel supply device of this document, the cylinder # 1 and cylinder # 4 in the four-cylinder internal combustion engine are in the first cylinder group, and the cylinder # 3 and cylinder # 2 in the engine are in the second cylinder group. A set high pressure fuel pump is provided. In the internal combustion engine provided with the fuel supply device, as the crankshaft rotates, the cylinders of the first cylinder group and the cylinders of the second cylinder group alternately reach the fuel injection timing.

  In the fuel supply device, when the internal combustion engine is started, when the first fuel injection is performed in the cylinders # 1 and # 4 of the first cylinder group, the second fuel after the start of the start is started. There is a possibility that the fuel injection in the cylinders # 3 and # 2 of the second cylinder group in which the injection is performed is not properly performed. The following points [1] and [2] are related to the occurrence of such problems. [1] After starting the engine, the cylinder of the first cylinder group reaches the fuel injection timing in a state where the fuel pressure of the delivery pipe has increased to the target value, and after starting the engine from the fuel injection valve of the cylinder at the fuel injection timing When the first fuel injection in the internal combustion engine is performed, the fuel pressure is reduced below the combustible fuel pressure. [2] The first fuel injection of the internal combustion engine after the start of the engine start is performed in the cylinders of the upper first cylinder group, and the next fuel injection (the second fuel injection in the internal combustion engine after the start of the engine start) is performed. In the meantime, the fuel pressure cannot be increased above the combustible fuel pressure.

  Note that the above point [2] occurs because the period during which the high-pressure fuel pump is pumped between fuel injection timings is the same as when the fuel injection timing is shifted from the first cylinder group to the second cylinder group. It can be mentioned that the fuel injection timing is shorter than that at the time of transition from the second cylinder group to the first cylinder group. When the fuel injection timing is shifted from the first cylinder group to the second cylinder group, the period during which the high-pressure fuel pump performs the pressure-feed stroke is shortened as described above. This means that the high-pressure fuel pump is pumped during the same period. As a result, the fuel pressure cannot be increased to the combustible fuel pressure.

In order to avoid such problems, it is conceivable to set the target value of the fuel pressure to a larger value. Specifically, when the first fuel injection in the internal combustion engine after the start of the start is performed in the cylinders of the first cylinder group as the target value, the fuel pressure is set to the next fuel injection timing after the first fuel injection. It is conceivable to set a large value so that the value is not insufficient for proper fuel injection at (the fuel injection timing in the cylinders of the second cylinder group). By setting the target value to a large value in this manner, after the start of the internal combustion engine, when the cylinder in which fuel is first injected is the cylinder of the first cylinder group, the second time after the start of the start is started. It is possible to avoid the occurrence of the above-described problem that fuel injection is not properly performed in the cylinders of the second cylinder group in which the fuel injection is performed.
JP 2006-188971 (FIG. 2)

  As described above, the above problem can be avoided by setting the target value of the fuel pressure to a large value. However, even when the cylinder in which the fuel injection is initially performed in the internal combustion engine after the start is the cylinder of the second cylinder group, the condition in which the first fuel injection is performed is set to the target value set to the above large value. The fuel pressure will be reached. For this reason, the first fuel injection is performed in the cylinders of the second cylinder group after the fuel pressure is unnecessarily large in view of properly performing the fuel injection.

  Here, when the first fuel injection in the internal combustion engine after the start of the start is performed in the cylinders of the second cylinder group, even if the fuel pressure decreases with the first fuel injection, the fuel pressure is used for the next fuel injection. It is easy to raise the fuel pressure above the combustible fuel pressure by (fuel injection in the cylinders of the first cylinder group). This is because the period during which the high pressure fuel pump is pumped between the fuel injection timings is changed from the first cylinder group at the same fuel injection timing to the second when the fuel injection timing is shifted from the second cylinder group to the first cylinder group. This is because the length is longer than that when shifting to the cylinder group. When the fuel injection timing is shifted from the second cylinder group to the first cylinder group, the period during which the pressure feeding stroke is performed by the high pressure fuel pump becomes longer as described above. This means that the amount of fuel to be increased increases, whereby the fuel pressure can be increased to the combustible fuel pressure.

  Therefore, when the cylinder in which the fuel injection is first performed in the internal combustion engine after the start of the start is the cylinder of the second cylinder group, the fuel injection is performed if the target value of the fuel pressure is set to a large value as described above. From the viewpoint of performing properly, the fuel injection is performed after the fuel pressure is unnecessarily large, and it is inevitable that the start of the fuel injection is delayed.

  The present invention has been made in view of such a situation, and its object is to provide the first in the case where the cylinder in which fuel is first injected in the internal combustion engine after the start of starting is the cylinder of the second cylinder group. An object of the present invention is to provide a fuel supply device for an internal combustion engine that can suppress delay of fuel injection.

In the following, means for achieving the above object and its effects are described.
In order to achieve the above object, according to the first aspect of the present invention, fuel injection from the fuel injection valve in each cylinder is executed when the fuel injection timing of each cylinder comes when the crankshaft rotates after the engine start is started. A fuel supply device for an internal combustion engine, which is driven by a cam that rotates as the crankshaft rotates, repeats the suction stroke and the pressure feed stroke, and the pressure feed stroke is reduced every time the fuel injection timing is reached twice. A high-pressure fuel pump that is operated once, and a delivery pipe that stores high-pressure fuel discharged from the high-pressure fuel pump during the pumping stroke and supplies the high-pressure fuel pump to the fuel injection valve. Until the fuel pressure rises to reach the target value, fuel injection from the fuel injection valve is prohibited, and the condition is that the fuel pressure has reached the target value. In the fuel supply device for an internal combustion engine that permits fuel injection from a fuel injection valve, the high-pressure fuel between the current fuel injection timing and the previous fuel injection timing when the fuel injection timing is reached for each cylinder. The first cylinder group in which the pumping stroke period is longer than the pressure feeding stroke period of the high-pressure fuel pump between the current fuel injection timing and the next fuel injection timing, and when the fuel injection timing comes The period of the pressure stroke of the high pressure fuel pump between the current fuel injection timing and the previous fuel injection timing is the period of the pressure stroke of the high pressure fuel pump between the current fuel injection timing and the next fuel injection timing. The second cylinder group is shorter than the first cylinder group, and the first cylinder is rotated along with the rotation of the crankshaft. The cylinders of the cylinder group and the cylinders of the second cylinder group alternately reach the fuel injection timing, and when the fuel injection timing comes after the start of engine start, the cylinder that has reached the fuel injection timing is the first cylinder If it is a cylinder of a group, fuel injection from the fuel injection valve of the cylinder is permitted on the condition that the fuel pressure in the delivery pipe has risen to a first target value or more, and the fuel injection timing is reached. If the cylinder is a second cylinder group, fuel injection from the fuel injection valve of the cylinder is permitted on the condition that the fuel pressure has risen to a second target value or more, and the first target value The second target value is set such that the second target value is set to be smaller than the first target value.

  According to the above configuration, the first target value and the second target value can be set as follows. That is, when the first fuel injection in the internal combustion engine after starting is performed in the cylinders of the first cylinder group, the fuel pressure is changed to the next fuel injection timing (in the cylinders of the second cylinder group) after the first fuel injection. The first target value is set to a large value so as not to become a value that is insufficient for proper fuel injection at the fuel injection timing). And after setting a 1st target value in this way, a 2nd target value can be set to a value smaller than the said 1st target value. Therefore, when the cylinder in which the fuel injection is first performed in the internal combustion engine after the start is the cylinder of the second cylinder group, the condition in which the first fuel injection is performed is a value smaller than the first target value. That is, the fuel pressure reaches the second target value. For this reason, the first fuel injection in the cylinders of the second cylinder group is not performed after the fuel pressure is unnecessarily increased from the viewpoint of properly performing the fuel injection. If the first fuel injection in the cylinders of the second cylinder group is not performed until the fuel pressure is unnecessarily large, it is inevitable that the start of the first fuel injection is delayed. However, as described above, by setting the second target value to a value smaller than the first target value, the initial value in the cylinders of the second cylinder group until the fuel pressure is unnecessarily large. Occurrence of a situation in which fuel injection is not performed is suppressed, and the start of the first fuel injection due to the occurrence of the situation can be suppressed from being delayed.

  According to a second aspect of the present invention, in the first aspect of the invention, with respect to the cylinders of the first cylinder group, when the cylinder reaches the fuel injection timing, the current fuel injection timing and the previous fuel injection timing are There is a pressure feed stroke of the high pressure fuel pump in between, and there is no pressure feed stroke of the high pressure fuel pump between the current fuel injection timing and the next fuel injection timing, and the cylinders of the second cylinder group When the cylinder has reached the fuel injection timing, there is no pumping stroke of the high-pressure fuel pump between the current fuel injection timing and the previous fuel injection timing, and the current fuel injection timing and the next time The gist is that the high-pressure fuel pump has a pumping stroke between the fuel injection timing.

  According to the above configuration, when the first fuel injection in the internal combustion engine after starting is performed in the cylinders of the first cylinder group, the next fuel injection (fuel injection in the cylinders of the second cylinder group) is performed. Since the fuel is not pumped from the high pressure fuel pump, the fuel pressure is greatly reduced after the first fuel injection is performed. Therefore, in the next fuel injection, there is a high possibility that the fuel pressure will be insufficient for properly performing the fuel injection. However, the first target value can be set to a large value so that such fuel pressure shortage does not occur.

  Here, if the first fuel injection after the start of engine start is performed in the cylinders of the first cylinder group and the cylinders in the second cylinder group, a common value as the target value of the fuel pressure is respectively set. If used, in other words, if the second target value is set equal to the first target value, the following problem occurs. In other words, when the first fuel injection after the start of the engine is performed in the cylinders of the second cylinder group, the first fuel injection is performed after the fuel pressure is increased to a uselessly large value in view of properly performing the fuel injection. The wasteful increase in the fuel pressure is further increased. Then, the start of the first fuel injection is further delayed due to the increase in the useless increase in the fuel pressure.

  However, according to the above configuration, since the second target value is set to a value smaller than the first target value, the above-described unnecessary increase in fuel pressure is reduced. As a result, it is possible to suppress the occurrence of the above-described problem that the first fuel injection in the cylinders of the second cylinder group is further delayed.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, the first target value is started by the internal combustion engine when the cylinders of the first cylinder group reach the fuel injection timing after the start of the engine is started. After the fuel injection from the first fuel injection valve after the start is performed, the fuel pressure that has decreased due to the fuel injection is set to a value that can properly perform the fuel injection from the fuel injection valve. With respect to the second target value, the cylinders of the second cylinder group reach the first fuel injection timing in the internal combustion engine after the start of the engine start, and from the first fuel injection valve after the start of the start in the internal combustion engine. When the fuel injection is performed, the gist of the invention is that the fuel injection is set to a minimum value capable of appropriately performing the fuel injection.

  According to the above configuration, since the second target value is set to a minimum value at which the fuel injection can be properly performed, the fuel pressure of the delivery pipe reaches the second target value after the engine start is started. The time required to ascend can be made as short as possible. Therefore, when the first fuel injection after the start of the engine is started in the cylinders of the second cylinder group, the first fuel injection can be performed as early as possible. Even if the fuel pressure decreases with the first fuel injection, the fuel pressure can be increased to the minimum value required for proper fuel injection before the next fuel injection. Will not be able to be performed properly. This is because, when the first fuel injection after the start of the engine is started is performed in the cylinders of the second cylinder group, the period of the pumping stroke of the high-pressure fuel pump until the next fuel injection is performed becomes longer.

  According to a fourth aspect of the invention, in the invention according to any one of the first to third aspects, when the cylinder in which fuel is first injected after the start of the engine is the cylinder of the first cylinder group, And a correction means for correcting the decrease in the fuel injection amount in the fuel injection.

  According to the above configuration, when the first fuel injection after the start of the engine is performed in the cylinders of the first cylinder group, even if the fuel pressure of the delivery pipe is decreased due to the first fuel injection, the decrease is reduced to the first. It is possible to reduce the fuel injection amount by correcting the decrease in the fuel injection amount. Therefore, in the next fuel injection (fuel injection in the cylinders of the second cylinder group), the fuel injection is prevented from being adversely affected by the decrease in the fuel pressure.

  According to a fifth aspect of the present invention, in the fourth aspect of the present invention, when the first fuel injection after the start of engine start is performed in the cylinders of the first cylinder group, the correction means is configured such that the fuel pressure at that time is The gist is that the smaller the value, the larger the correction amount when the fuel injection amount is corrected to decrease.

  When the first fuel injection after the start of the engine is performed in the cylinders of the first cylinder group, the lower the fuel pressure at that time, the lower the fuel pressure associated with the execution of the first fuel injection occurs. The fuel pressure becomes a small value, and there is a high possibility that the next fuel injection (fuel injection in the cylinders of the second cylinder group) will be adversely affected. According to the above configuration, the smaller the value of the fuel pressure when the first fuel injection is performed in the cylinders of the first cylinder group, the smaller the correction amount when the fuel injection amount in the first fuel injection is corrected to decrease. Since the fuel pressure is increased, a decrease in fuel pressure accompanying the fuel injection can be suppressed to a small level. Accordingly, it is possible to accurately suppress the decrease in fuel pressure caused by the first fuel injection in the cylinders of the first cylinder group from adversely affecting the next fuel injection (fuel injection in the cylinders of the second cylinder group). It becomes like this.

[First Embodiment]
Hereinafter, a first embodiment in which the present invention is applied to a V-type six-cylinder in-cylinder internal combustion engine mounted on an automobile will be described with reference to FIGS.

  In the internal combustion engine 31 shown in FIG. 1, a fuel injection valve 3 that injects fuel into each of the six cylinders # 1 to # 6 toward the combustion chamber 32 is provided. The crankshaft 33, which is the output shaft of the engine 31, is rotated by the combustion energy when it is burned.

  In such an in-cylinder injection type internal combustion engine 31, high-pressure fuel is supplied to the fuel injection valve 3 in order to enable fuel injection from the fuel injection valve 3 against the pressure in the combustion chamber 32 that becomes high pressure. A fuel supply device is provided. The apparatus includes a high-pressure fuel pump 4 that boosts and discharges the fuel pumped from the fuel tank 1 by the feed pump 2, and stores the fuel discharged from the high-pressure fuel pump 4 in each cylinder # 1-# 6. A delivery pipe 13 that distributes to the fuel injection valve 3 is provided.

  The high-pressure fuel pump 4 reciprocates in the cylinder 9 based on the rotation of the cam 6 attached to the exhaust camshaft 5 rotating with the rotation of the crankshaft 33 of the internal combustion engine 31 and the biasing force of the coil spring 7. A plunger 8 is provided. With respect to the exhaust camshaft 5 to which the cam 6 for reciprocating the plunger 8 is attached, rotation transmission from the crankshaft 33 is performed so as to make one rotation for every two rotations of the crankshaft 33 of the internal combustion engine 31. Is called. The cam 6 is formed with three cam peaks at equal intervals in the rotational direction of the exhaust camshaft 5.

  The high-pressure fuel pump 4 is formed with a pressurizing chamber 10 which is partitioned by a plunger 8 and a cylinder 9 and whose volume changes as the plunger 8 reciprocates. As the cam 6 rotates, the suction stroke in which the plunger 8 moves in the direction of expanding the pressurizing chamber 10 and the pressure feeding stroke in which the plunger 8 moves in the direction of reducing the pressurizing chamber 10 are alternately performed. Repeated. The suction stroke is a stroke in which the fuel from the feed pump 2 is sucked into the pressurizing chamber 10 through the suction passage 11. The pressure feeding stroke is the fuel in the pressurizing chamber 10 being pressurized and discharged into the discharge passage 12. Is the process. The high-pressure fuel discharged from the high-pressure fuel pump 4 in this pressure feed stroke is supplied to the delivery pipe 13 through the discharge passage 12 and the check valve 16 provided in the middle thereof.

  With respect to such a pumping stroke and a suction stroke, three cam peaks are formed in the cam 6, so that the rotation of the crankshaft 33 of the internal combustion engine 31 is rotated by 720 ° for each rotation of the exhaust camshaft 5. Each (two rotations) is performed three times. Incidentally, in the V-type 6-cylinder internal combustion engine 31, the fuel injection timing is reached once for each of the cylinders # 1 to # 6 for each 720 ° rotation of the crankshaft 33, and the fuel injection is performed every time the fuel injection timing is reached. Fuel injection from the valve 3 is performed. Therefore, in the internal combustion engine 31, the pressure feeding stroke and the suction stroke of the high pressure fuel pump 4 are performed once each time the fuel injection timing is reached twice.

  The high-pressure fuel pump 4 is provided with an electromagnetic spill valve 14 that opens and closes so as to communicate and block between the suction passage 11 and the pressurizing chamber 10. The electromagnetic spill valve 14 includes an electromagnetic solenoid 15 and opens and closes by controlling voltage application to the solenoid 15. In other words, in the state where the energization to the electromagnetic solenoid 15 is stopped, the electromagnetic spill valve 14 is opened by the urging force of the coil spring 17 and the suction passage 11 and the pressurizing chamber 10 are in communication with each other. When the electromagnetic solenoid 15 is energized, the electromagnetic spill valve 14 is closed against the biasing force of the coil spring 17 and the suction passage 11 and the pressurizing chamber 10 are shut off.

  In the high-pressure fuel pump 4, the electromagnetic spill valve 14 is opened during the intake stroke, thereby permitting fuel to flow from the intake passage 11 into the pressurizing chamber 10. In the pressure feed stroke, the electromagnetic spill valve 14 is closed only for a predetermined period, and the fuel in the pressurizing chamber 10 overflows into the suction passage 11 while the spill valve 14 is opened, and the spill The overflow is prohibited while the valve 14 is closed. Thus, when the overflow of the fuel is prohibited, the fuel in the pressurizing chamber 10 is discharged into the discharge passage 12 in a pressurized state. Therefore, the fuel discharge amount of the high-pressure fuel pump 4 is adjusted by controlling the valve closing time of the electromagnetic spill valve 14 in the pressure feed stroke and adjusting the amount of fuel overflowing from the pressurizing chamber 10 to the suction passage 11. be able to.

  The drive control of the fuel supply device including the high-pressure fuel pump 4 is performed by an electronic control device 18 that controls various devices mounted on the automobile. The electronic control unit 18 includes a CPU that executes various calculations related to the above control, a ROM that stores programs and data necessary for the control, a RAM that temporarily stores the calculation results of the CPU, and signals between the outside Are provided with an input / output port and the like.

Various sensors including the following sensors are connected to the input port of the electronic control unit 18.
A fuel pressure sensor 19 that detects fuel pressure in the delivery pipe 13 (pressure of fuel supplied to the fuel injection valve 3).

A crank position sensor 20 that outputs a pulse-like signal corresponding to the rotation of the crankshaft 33 of the internal combustion engine 31 and is used for detecting the engine rotational speed.
A cam position sensor 21 that outputs a signal corresponding to the rotational position of the exhaust shaft 5 corresponding to the rotation of the exhaust cam shaft 5 of the internal combustion engine 31.

A water temperature sensor 22 that detects the cooling water temperature of the internal combustion engine 31.
Drive circuits of various devices such as the fuel injection valve 3 and the electromagnetic spill valve 14 are connected to the output port of the electronic control unit 18.

  The electronic control unit 18 outputs a command signal to the drive circuit of various devices connected to the output port in accordance with the engine operation state grasped by the detection signals from the various sensors, and executes control of those devices. . In this way, various controls such as the fuel injection control of the fuel injection valve 3 and the fuel pressure control of the delivery pipe 13 in the internal combustion engine 31 are performed by the electronic control unit 18.

  Here, the fuel pressure control in the delivery pipe 13 is performed by setting the closing time of the electromagnetic spill valve 14 during the pumping stroke of the high-pressure fuel pump 4 based on the pump duty DT which is a drive command value when driving the high-pressure fuel pump 4. This is realized by controlling and adjusting the fuel discharge amount from the high-pressure fuel pump 4.

  FIG. 2 is a timing chart for explaining the pump duty DT, and shows a change in the lift amount of the plunger 8 with respect to a change in the cam angle of the cam 6. In the figure, “θ0” represents the cam angle (maximum cam angle) of the cam 6 corresponding to the entire pumping stroke of the high-pressure fuel pump 4, and “θ” represents the valve closing time of the electromagnetic spill valve 14 during the pumping stroke. The cam angle of the cam 6 (target cam angle) corresponding to the target value is shown. The pump duty DT indicates the ratio of the target cam angle θ to the maximum cam angle θ0, and is a value that can be varied within a range of 0 to 100%.

  The closer this pump duty DT is to "0%", the shorter the valve closing time during the pumping stroke of the electromagnetic spill valve 14 controlled based on the pump duty DT. As a result, the amount of fuel discharged from the high-pressure fuel pump 4 decreases, and the fuel pressure in the delivery pipe 13 decreases. Conversely, the closer the pump duty DT is to “100%, the shorter the valve closing time during the pumping stroke of the electromagnetic spill valve 14 controlled based on the pump duty DT. As a result, the fuel from the high-pressure fuel pump 4 is reduced. The discharge amount increases and the fuel pressure in the delivery pipe 13 increases.

  The pump duty DT is variably set between 0% and 100% so that the fuel pressure in the delivery pipe 13 becomes the target value. The target value is set to a value equal to or greater than a value (for example, about 6 MPa) at which fuel can be directly injected from the fuel injection valve 3 into the combustion chamber 32. Therefore, the fuel pressure in the delivery pipe 13 is controlled by controlling the valve closing time of the electromagnetic spill valve 14 during the pumping stroke of the high-pressure fuel pump 4 based on the pump duty DT and adjusting the fuel discharge amount from the high-pressure fuel pump 4. Is controlled to the target value, and the fuel can be directly injected from the fuel injection valve 3 into the combustion chamber 32.

  By the way, when the internal combustion engine 31 is stopped and the drive of the high-pressure fuel pump 4 is stopped, the high-pressure fuel is not supplied to the delivery pipe 13, so a check provided in the middle of the discharge passage 12. It is inevitable that the fuel pressure in the delivery pipe 13 drops due to fuel leakage from the delivery pipe 13 side to the pressurizing chamber 10 side in the valve 16. Therefore, while the internal combustion engine 31 is stopped, the fuel pressure in the delivery pipe 13 decreases to a value less than the target value. When the internal combustion engine 31 is started in such a state, the high-pressure fuel pump 4 is driven as the crankshaft 33 of the internal combustion engine 31 rotates, and the fuel pressure in the delivery pipe 13 is set to the target value based on the drive of the pump 4. Until it rises, it becomes difficult to perform proper fuel injection from the fuel injection valve 3 into the combustion chamber 32.

  Incidentally, when the crankshaft 33 rotates immediately after the start of the internal combustion engine 31, the fuel injection from the fuel injection valve 3 is performed at the fuel injection timing set for each predetermined crank angle. Therefore, even if fuel injection from the fuel injection valve 3 is performed at the fuel injection timing after the start of the engine, if the fuel pressure in the delivery pipe 13 does not reach the target value at that time, the fuel injection is performed. Proper fuel injection from the valve 3 cannot be performed. The pump duty DT is set to “100%” so that the fuel pressure reaches the target value as early as possible until the fuel pressure in the delivery pipe 13 reaches the target value after the engine start is started. The high-pressure fuel is discharged from the high-pressure fuel pump 4 throughout the pressure feed stroke (see FIG. 2). However, even if the fuel pressure is increased by using the full capacity of the high-pressure fuel pump 4 in this way, the fuel pressure does not necessarily reach the target value by the first fuel injection timing after starting the engine.

  For this reason, fuel injection from the fuel injection valve 3 is prohibited until the fuel pressure in the delivery pipe 13 rises and reaches the target value from the start of engine start, on condition that the fuel pressure has reached the target value. Allowing fuel injection from the fuel injection valve 3 is performed. In this case, after the engine is started, before the fuel pressure in the delivery pipe 13 rises to the target value, fuel injection from the fuel injection valve 3 is not performed even if the fuel injection timing is reached. Accordingly, the fuel injection from the fuel injection valve 3 is performed at the fuel injection timing while the fuel pressure has not risen to the target value and proper fuel injection into the combustion chamber 32 cannot be performed. Can be avoided.

  Next, the setting of the relative rotation phase of the cam 6 with respect to the crankshaft 33 in this embodiment, in other words, the setting of the pumping stroke of the high-pressure fuel pump 4 with respect to the fuel injection timing will be described with reference to FIG.

  In the figure, the horizontal axis indicates the change in crank angle (0 to 720 ° CA) for one cycle of the internal combustion engine 31, and # 1inj to # 6inj on the horizontal axis are the cylinders immediately after the start of engine start. The fuel injection timing in FIG. Accordingly, the fuel injection timing in the internal combustion engine 31 of this embodiment is 510 ° CA (# 1 inj), 630 ° CA (# 2 inj), 30 ° CA (# 3 inj), 150 ° CA (# 4 inj), 270 °. CA (# 5 inj), 390 ° CA (# 6 inj).

  As can be seen from FIG. 5A, with respect to the cam crest of the cam 6 of the high-pressure fuel pump 4, one pumping stroke of the high-pressure fuel pump 4 is generated by the 90 ° rotation of the crankshaft 33, and the high-pressure fuel A single suction stroke of the pump 4 is formed so as to occur when the crankshaft 33 rotates by 150 °. Further, the relative rotational phase of the cam 6 with respect to the crankshaft 33 is set so that the high-pressure fuel pump 4 has a pumping stroke at 570 to 660 ° CA, 90 to 180 ° CA, and 330 to 420 ° CA. For this reason, the pumping stroke of the high-pressure fuel pump 4 is performed once every time the fuel injection timing of each cylinder # 1 to # 6 in the internal combustion engine 31 is reached twice.

  Thus, when the pumping stroke of the high-pressure fuel pump 4 is performed once every two fuel injection timings, each cylinder # 1 to # 6 of the internal combustion engine 31 has a first cylinder group and a second cylinder group, which will be described later. It is divided into.

  Here, the first cylinder group refers to the period of the pumping stroke of the high pressure fuel pump 4 between the current fuel injection timing and the previous fuel injection timing when the fuel injection timing is reached. This is a cylinder group that is longer than the period of the pumping stroke of the high-pressure fuel pump 4 between the next fuel injection timing. Therefore, in the example of FIG. 3, cylinders # 2, # 4, and # 6 are cylinders of the first cylinder group. In the cylinders of the first cylinder group, when the fuel injection timing is reached, the period of the pumping stroke between the current fuel injection timing and the previous fuel injection timing is 60 ° rotation of the crankshaft 33, and The period of the pumping stroke between the current fuel injection timing and the next fuel injection timing corresponds to the rotation of the crankshaft 33 by 30 °.

  In addition, the second cylinder group means that the period of the pumping stroke of the high-pressure fuel pump 4 between the current fuel injection timing and the previous fuel injection timing when the fuel injection timing comes, This is a cylinder group that is shorter than the period of the pumping stroke of the high-pressure fuel pump 4 between the two fuel injection timings. Accordingly, in the example of FIG. 3, cylinders # 1, # 3, and # 5 are cylinders of the second cylinder group. In the cylinders of the second cylinder group, when the fuel injection timing is reached, the period of the pumping stroke between the current fuel injection timing and the previous fuel injection timing is 30 ° rotation of the crankshaft 33, and this time The period of the pumping stroke between the next fuel injection timing and the next fuel injection timing is the crankshaft 60 ° rotation.

Next, a problem that occurs in relation to the fuel pressure of the delivery pipe 13 when the internal combustion engine 31 that is divided into the first cylinder group and the second cylinder group described above is started will be described.
After the start of the internal combustion engine 31, when the fuel pressure in the delivery pipe 13 rises and exceeds the target value Pt, fuel injection from the fuel injection valve 3 is permitted and any cylinder # 1 to # 6 of the internal combustion engine 31 is allowed. When the fuel injection timing comes, the first fuel injection from the fuel injection valve 3 after the start of the internal combustion engine 31 is performed at the same timing. In the example of FIG. 3B, at the fuel injection timing # 4inj of the cylinder # 4, the fuel pressure becomes equal to or higher than the target value Pt, the fuel injection from the fuel injection valve 3 is permitted, and the cylinder # 4 The first fuel injection after the start of the internal combustion engine 31 is performed from the fuel injection valve 3.

  The target value Pt is set to a minimum value (hereinafter referred to as combustible fuel pressure) that can properly perform fuel injection from the fuel injection valve 3 and properly perform fuel combustion in the combustion chamber 32. On the other hand, it is conceivable to adopt a value larger by a predetermined value a. Further, regarding the fuel injection amount from the start of the internal combustion engine 31 to the start of the self-sustained operation after the completion of the start, in order to improve the startability of the engine 31, as much as possible within the range where the fuel can be combusted. It is conceivable to adjust the maximum value (rich limit value) in the same range to inject a lot of fuel.

  Here, after the start of the internal combustion engine 31, the cylinder in which fuel is injected from the fuel injection valve 3 is a cylinder of the first cylinder group (for example, cylinder) based on the fact that the fuel pressure of the delivery pipe 13 becomes equal to or higher than the target value Pt. In the case of # 4), there is a possibility that the fuel injection in the cylinder of the second cylinder group (cylinder # 5 in the above example) in which the second fuel injection after the start of the start is performed is not properly performed. The occurrence of such problems is related to the following points [1] and [2] described in the [Background Art] column.

  [1] When the first fuel injection is performed in the internal combustion engine 31 after starting from the fuel injection valve 3 in the cylinder of the first cylinder group (cylinder # 4 in the example of FIG. 3B), the fuel pressure is increased accordingly. It falls below the combustible fuel pressure. In the example of FIG. 3B, since the 30 ° rotation of the crankshaft 33 after the first fuel injection is performed becomes the pumping stroke of the high-pressure fuel pump 4, the fuel accompanying the first fuel injection Although the pressure drop can be suppressed, it cannot be avoided. For this reason, with the first fuel injection, the fuel pressure falls below the combustion permission fuel pressure.

  [2] In the cylinder of the upper first cylinder group (cylinder # 4 in the above example), the first fuel injection in the internal combustion engine 31 after the start of the start is performed, and then the cylinder of the second cylinder group (the above example) Then, the fuel pressure cannot be increased above the combustible fuel pressure until the next fuel injection (second time after start of start) performed in cylinder # 5). This is because the period during which the high pressure fuel pump 4 performs the pressure stroke between the fuel injection timings is when the fuel injection timing is shifted from the first cylinder group to the second cylinder group (# 4 inj → # 5 inj in the above example). This is because the fuel injection timing is shorter than that at the time of transition from the second cylinder group to the first cylinder group (# 5inj → # 6inj, etc.). When the fuel injection timing is shifted from the first cylinder group to the second cylinder group, the period during which the high-pressure fuel pump 4 performs the pumping stroke is shortened as described above. This means that the amount of fuel pumped is reduced. As a result, the fuel pressure cannot be increased to the combustible fuel pressure.

  From the relationship between the points [1] and [2] above, in the internal combustion engine 31 after the start of the start, when the cylinder in which the fuel injection from the fuel injection valve 3 is first performed is the cylinder of the first cylinder group, the start There is a possibility that the fuel injection from the fuel injection valve 3 is not properly performed in the cylinders of the second cylinder group in which the second fuel injection after the start is performed. As a countermeasure against such a problem, it is conceivable to set the target value of the fuel pressure to a value larger than the target value Pt.

  Specifically, when the first fuel injection in the internal combustion engine 31 after the start of the start is performed in the cylinders of the first cylinder group, the fuel pressure is changed to the next fuel injection timing (second cylinder) after the first fuel injection. The target value is set to a value larger than the target value Pt so as not to become a value insufficient for proper fuel injection at the fuel injection timing in the cylinders of the group). If the target value at this time is the target value Pt1 shown in FIG. 3C, the first fuel injection in the internal combustion engine 31 after the start of the start is performed in the cylinders of the first cylinder group (cylinder # 4, etc.). The fuel pressure does not become less than the combustible fuel pressure when the fuel pressure decreases from the target value Pt1 with the fuel injection. For this reason, the occurrence of the above-described problem that the fuel injection is not properly performed in the cylinders of the second cylinder group (cylinder # 5 or the like) in which the second fuel injection is started after the start of the internal combustion engine 31 is avoided. can do.

  However, if the target value of the fuel pressure is set to a large value such as the above-described target value Pt1, even when the cylinder in which fuel is first injected in the internal combustion engine 31 after the start of starting is the cylinder of the second cylinder group, This means that the fuel pressure reaches the target value Pt1 that is set to the above large value as the condition for the first fuel injection. For this reason, the first fuel injection is performed in the cylinders of the second cylinder group after the fuel pressure is unnecessarily large in view of properly performing the fuel injection.

  Here, when the first fuel injection in the internal combustion engine 31 after the start of the start is performed in the cylinders of the second cylinder group, even if the fuel pressure is reduced due to the first fuel injection, the fuel pressure is changed to the next fuel pressure. It is easy to raise the fuel pressure to be higher than the combustible fuel pressure before injection (fuel injection in the cylinders of the first cylinder group). This is because the period during which the pressure-feed stroke of the high-pressure fuel pump 4 is performed between the fuel injection timings is changed from the first cylinder group at the same fuel injection timing to the first when the fuel injection timing is shifted from the second cylinder group to the first cylinder group. This is because the length becomes longer than that when shifting to the two-cylinder group. When the fuel injection timing is shifted from the second cylinder group to the first cylinder group, the period during which the high pressure fuel pump 4 performs the pressure feed stroke becomes longer as described above. This means that the amount of fuel to be pumped is increased, whereby the fuel pressure can be increased to the combustible fuel pressure.

  Therefore, when the target value of the fuel pressure is set to a large value as the target value Pt1, the fuel injection is performed when the first fuel injection cylinder in the internal combustion engine 31 after the start of the start is the cylinder of the second cylinder group. From the viewpoint of performing properly, the fuel injection is performed after the fuel pressure is unnecessarily large, and it is inevitable that the start of the fuel injection is delayed.

  As a specific example, after the start of the internal combustion engine 31, the fuel pressure rises to the target value Pt1, and as shown in FIG. 3D, at the fuel injection timing # 5inj in the cylinder # 5 of the second cylinder group, Consider the case where the first fuel injection is performed in the internal combustion engine 31 after starting. In this case, from the viewpoint of properly performing the fuel injection, the fuel is injected to the extent that the first fuel injection can be performed in the internal combustion engine 31 after the start of the start at the fuel injection timing # 3inj in the cylinder # 3 of the second cylinder group. The pressure may have increased. Nevertheless, when the target value of the fuel pressure is set to the target value Pt1, there occurs a situation in which the first fuel injection is performed only at the fuel injection timing # 5inj in the cylinder # 5 of the second cylinder group. In the period from the fuel injection timing # 3inj to the fuel injection timing # 5inj, the start of the first fuel injection in the internal combustion engine 31 after the start of the start is delayed.

  Next, in the case where the first fuel injection in the internal combustion engine 31 after starting is the cylinder of the second cylinder group, the countermeasure of the present embodiment regarding the problem that the first fuel injection is delayed will be described with reference to FIG. Will be described with reference to FIG. In the figure, (a) shows a mode of switching between a pumping stroke and a suction stroke in the high-pressure fuel pump 4 with respect to a change in the crank angle, and (b) and (c) are after the start of the internal combustion engine 31 is started. The change of the fuel pressure with time in FIG.

  When the fuel injection timing comes after the start of the internal combustion engine 31, the fuel injection depends on whether the cylinder that has reached the fuel injection timing is a cylinder of the first cylinder group or a cylinder of the second cylinder group The target value of the fuel pressure used for determining whether or not to permit fuel injection from the valve 3 is set to a different value.

  More specifically, when the fuel injection timing comes after the start of the internal combustion engine 31, and the cylinder that has reached the fuel injection timing is a cylinder of the first cylinder group, the target value of the fuel pressure is the target value Pt1. Is set to a first target value Pt1 that is equal to The first target value Pt1 at this time is shown in FIG. On the other hand, when the fuel injection timing comes after the start of the internal combustion engine 31 and the cylinder that has reached the fuel injection timing is a cylinder of the second cylinder group, the target value of the fuel pressure is the first target value. The second target value Pt2 is set to a value smaller than Pt1. Incidentally, with respect to the second target value Pt2, when the first fuel injection in the internal combustion engine 31 is performed in the cylinders of the second cylinder group after the start of the start, the minimum possible fuel injection can be appropriately performed. The value is set to the combustible fuel pressure. The second target value Pt2 at this time is shown in FIG.

  When the cylinder in which the fuel injection is first performed in the internal combustion engine 31 after the start is the cylinder of the second cylinder group, the condition in which the first fuel injection is performed is a value smaller than the first target value Pt1. That is, the fuel pressure reaches the second target value Pt2. For this reason, the first fuel injection in the cylinders of the second cylinder group is not performed after the fuel pressure is unnecessarily increased from the viewpoint of properly performing the fuel injection. As described above, since the situation in which the first fuel injection in the cylinders of the second cylinder group is not performed until the fuel pressure is unnecessarily large is suppressed, the occurrence of the situation is suppressed. It becomes possible to suppress the start of the first fuel injection from being delayed. When the first fuel injection in the internal combustion engine 31 is performed in the cylinders of the second cylinder group after the start of the start, if the target value of the fuel pressure is set to the first target value Pt1, the fuel injection is performed at the fuel injection timing # 5inj, for example. In contrast, there is a case where the fuel injection can be performed at the fuel injection timing # 3inj by setting the target value to the second target value Pt2.

  Next, fuel injection control of the internal combustion engine 31 from the start to the start of self-sustained operation (start completion) will be described with reference to the flowchart of FIG. 5 showing the start-time fuel injection control routine. This start-up fuel injection control routine is periodically executed through an electronic control unit 18 with an angle interruption for each predetermined crank angle such as every 30 °.

  In this routine, it is determined whether the internal combustion engine 31 is before the start of self-sustained operation (S101), for example, whether the engine rotational speed is less than a predetermined value lower than the idle rotational speed. Here, if it is stroke determination, based on the cooling water temperature of the engine 31 that represents the engine temperature at the start of the internal combustion engine 31, the base value is a command value for the fuel injection amount from the start of the engine 31 to the start of independent operation. The injection amount B is calculated (S102). The base injection amount B calculated in this way is variable so as to be the maximum value (rich limit value) within the range in which the fuel can be combusted according to the cooling water temperature.

  Subsequently, it is determined whether or not the first fuel injection is not performed after the start of the internal combustion engine 31 (S103). If the determination is negative, every time the fuel injection timing is reached, the fuel injection valve 3 of the cylinder is injected from the fuel injection valve 3 of the cylinder that has reached the fuel injection timing. Driving is performed (S111).

  On the other hand, if an affirmative determination is made in step S103, when the first fuel injection in the internal combustion engine 31 after the start of the start is performed in the cylinders of the second cylinder group, the process for executing the first fuel injection ( S104 to S106) are performed. In this series of processing, whether or not the fuel injection timings # 1ing, # 3ing, # 5ing in the cylinders # 1, # 3, # 5 of the second cylinder group have been reached (S104), the fuel pressure is the second target value. It is determined whether or not it is greater than or equal to Pt2 (S105). If both of step S104 and step S105 are positive, fuel corresponding to the base injection amount B is injected from the fuel injection valves 3 of the cylinders # 1, # 3, and # 5 that have reached the same fuel injection timing. Then, the fuel injection valve 3 is driven (S106).

  On the other hand, if a negative determination is made in step S104, when the first fuel injection in the internal combustion engine 31 after the start of the start is performed in the cylinders of the first cylinder group, the process for executing the first fuel injection ( S107 to S110) are performed. In this series of processes, whether or not the fuel injection timings # 2ing, # 4ing, # 6ing in the cylinders # 2, # 4, # 6 of the first cylinder group have been reached (S107), the fuel pressure is the first target value. It is determined whether or not it is greater than or equal to Pt1 (S108). If both of step S107 and step S108 are affirmative, a reduction coefficient K used to correct the fuel injection amount in the first fuel injection based on the fuel pressure at that time is calculated ( S109). Then, the fuel injection valves 3 of the cylinders # 2, # 4, and # 6 in which fuel corresponding to the corrected injection amount B · K, which is a value obtained by multiplying the base injection amount B by the reduction coefficient K, has reached the fuel injection timing. The fuel injection valve 3 is driven so that the fuel is injected from the fuel (S110).

  Therefore, when the first fuel injection in the internal combustion engine 31 after starting is performed in the cylinders of the first cylinder group, the fuel injection amount at the time of the fuel injection is subjected to the reduction correction by the reduction coefficient K. The Rukoto. In this way, the reduction correction is performed on the fuel injection amount to suppress a decrease in the fuel pressure accompanying the first fuel injection in the cylinders of the first cylinder group, and the next fuel injection (cylinder of the second cylinder group). This is to prevent the fuel injection from being adversely affected by the decrease in the fuel pressure.

  As shown in FIG. 6, the weight loss coefficient K is “1.0” in the high pressure region R, which is the region where the fuel pressure is high, and the fuel pressure is changed from the minimum value in the high pressure region R to the first target value. When it is between Pt1, the value gradually decreases as the fuel pressure decreases. Therefore, when the fuel pressure is between the first target value Pt1 and the minimum value of the high pressure region R, the corrected injection amount B · K is subjected to the reduction correction by the reduction coefficient K with respect to the base injection amount B. Value. In such a reduction correction, the correction amount of the reduction correction increases as the reduction coefficient K becomes smaller than “1.0”. Further, when the fuel pressure is between the first target value Pt1 and the minimum value of the high pressure region R, the weight loss coefficient K when the fuel pressure is less than "1.0", that is, the weight loss coefficient K is set as follows. The reduction correction of the used fuel injection amount is calculated to be a value within a range that does not adversely affect the startability of the internal combustion engine 31.

According to the embodiment described in detail above, the following effects can be obtained.
(1) When the fuel injection timing comes after the start of the internal combustion engine 31, and the cylinder that has reached the fuel injection timing is a cylinder of the first cylinder group, the target value of the fuel pressure is the first target value Pt1. When the cylinder that has reached the fuel injection timing is a cylinder of the second cylinder group, the target value of the fuel pressure is set to the second target value Pt2. The first target value Pt1 and the second target value Pt2 are set so that the second target value Pt2 is smaller than the first target value Pt1.

  More specifically, regarding the first target value Pt1, when the first fuel injection in the internal combustion engine 31 after the start of the start is performed in the cylinders of the first cylinder group, the fuel pressure is changed to the next time after the first fuel injection. Is set to a large value so as not to become a value insufficient for proper fuel injection at the fuel injection timing (fuel injection timing in the cylinders of the second cylinder group). Then, the second target value Pt2 is set to be a value smaller than the first target value Pt1 set in this way.

  Therefore, when the cylinder in which the fuel injection is first performed in the internal combustion engine 31 after starting is the cylinder of the second cylinder group, the condition in which the first fuel injection is performed is more than the first target value Pt1. This means that the fuel pressure reaches the second target value Pt2 that is a small value. For this reason, the second pressure after the fuel pressure is unnecessarily large in terms of properly performing fuel injection as in the case where the target value of the fuel pressure is set to the first target value Pt1 under the above circumstances. The first fuel injection is not performed in the cylinders of this cylinder group.

  If the first fuel injection in the cylinders of the second cylinder group is not performed until the fuel pressure is unnecessarily large, it is inevitable that the start of the first fuel injection is delayed. However, as described above, by setting the second target value Pt2 to a value smaller than the first target value Pt1, the fuel pressure in the cylinders of the second cylinder group is increased until the fuel pressure is unnecessarily large. Occurrence of a situation in which the first fuel injection is not performed is suppressed, and the start of the first fuel injection can be prevented from being delayed due to the occurrence of the situation.

  (2) Regarding the second target value Pt2, when the first fuel injection in the internal combustion engine 31 is performed in the cylinders of the second cylinder group after the start of the start, the minimum possible fuel injection can be properly performed Is set to a combustible fuel pressure that is a value of. For this reason, the time required for the fuel pressure of the delivery pipe 13 to rise to the second target value Pt2 after the start of the engine can be shortened as much as possible. Therefore, when the first fuel injection after the start of the engine is started in the cylinders of the second cylinder group, the first fuel injection can be performed as early as possible. In addition, even if the fuel pressure decreases with the first fuel injection, the fuel pressure can be increased to the minimum value (combustible fuel pressure) necessary for proper fuel injection before the next fuel injection, The next fuel injection cannot be performed properly. This is because, when the first fuel injection after the start of the engine is started is performed in the cylinders of the second cylinder group, the period of the pumping stroke of the high-pressure fuel pump until the next fuel injection is performed becomes longer.

  (3) When the first fuel injection in the internal combustion engine 31 after starting is performed in the cylinders of the first cylinder group, the fuel injection amount at the time of the fuel injection is subjected to the reduction correction by the reduction coefficient K. The Thus, by performing a reduction correction on the fuel injection amount, a decrease in fuel pressure accompanying the first fuel injection in the cylinders of the first cylinder group is suppressed, and the next fuel injection (cylinder of the second cylinder group) is suppressed. The fuel injection can be prevented from being adversely affected by the decrease in the fuel pressure.

  (4) Regarding the weight reduction coefficient K, when the fuel injection timing in the cylinders of the first cylinder group comes after the start of the internal combustion engine 31, the fuel pressure is changed from the minimum value in the high pressure region R toward the first target value Pt1. As the value decreases, the value gradually decreases with respect to “1.0”. Thus, the smaller the fuel pressure becomes, the larger the correction amount when performing the reduction correction by the reduction coefficient K with respect to the fuel injection amount at the first fuel injection after the start of engine start performed at the fuel injection timing. Become. Here, when the first fuel injection after the start of the engine is performed in the cylinders of the first cylinder group, the lower the fuel pressure at that time, the lower the fuel pressure accompanying the execution of the first fuel injection. After the occurrence, the fuel pressure becomes a small value, and the possibility that the next fuel injection (fuel injection in the cylinders of the second cylinder group) will be adversely affected becomes high. However, since the reduction coefficient K used for correcting the reduction in the fuel injection amount in the first fuel injection is made variable according to the fuel pressure as described above, the decrease in the fuel pressure accompanying the fuel injection can be kept small. It becomes like this. Accordingly, it is possible to accurately suppress the decrease in fuel pressure caused by the first fuel injection in the cylinders of the first cylinder group from adversely affecting the next fuel injection (fuel injection in the cylinders of the second cylinder group). It becomes like this.

[Second Embodiment]
Next, a second embodiment of the present invention will be described with reference to FIG.
In this embodiment, the setting of the relative rotation phase of the cam 6 with respect to the crankshaft 33, in other words, the setting of the pumping stroke of the high-pressure fuel pump 4 with respect to the fuel injection timing is different from that of the first embodiment. 7A shows a mode of switching between a pumping stroke and a suction stroke in the high-pressure fuel pump 4 with respect to a change in the crank angle, and FIGS. 7B and 7C are diagrams after the start of the internal combustion engine 31 is started. The change of the fuel pressure with time in FIG.

  As can be seen from the figure, with respect to the relative rotational phase of the cam 6 with respect to the crankshaft 33 in this embodiment, the high pressure fuel pump 4 is pumped at 510 to 600 ° CA, 30 to 120 ° CA, and 270 to 360 ° CA. It is set to be a journey.

  In this case, regarding the cylinders # 2, # 4, and # 6 of the first cylinder group, the fuels of this time are reached when the cylinders # 2, # 4, and # 6 reach the fuel injection timings # 2inj, # 4inj, and # 6inj. There is a pumping stroke between the injection timing and the previous fuel injection timing, and there is no pumping stroke between the current fuel injection timing and the next fuel injection timing. In other words, the period of the pumping stroke that exists between the current fuel injection timing and the previous fuel injection timing is 90 ° rotation of the crankshaft 33, and the current fuel injection timing and the next fuel injection timing are The period of the pumping stroke existing between the two is the rotation of the crankshaft 33 by 0 °.

  Further, regarding the cylinders # 1, # 3, and # 5 of the second cylinder group, when the cylinders # 1, # 3, and # 5 reach the fuel injection timings # 1inj, # 3inj, and # 5inj, the current fuel injection is performed. There is no pumping stroke between the timing and the previous fuel injection timing, and there is a pumping stroke between the current fuel injection timing and the next fuel injection timing. In other words, the period of the pumping stroke that exists between the current fuel injection timing and the previous fuel injection timing is 0 ° rotation of the crankshaft 33, and the current fuel injection timing and the next fuel injection timing are The period of the pumping stroke that exists between the crankshaft 33 and the crankshaft 33 is 90 °.

  When the pumping stroke of the high-pressure fuel pump 4 is set as described above, the first fuel injection in the internal combustion engine 31 after the start of the start is the cylinder of the first cylinder group (cylinder # 4 in the example of FIG. 7B). Is performed, the fuel is not pumped from the high-pressure fuel pump 4 until the next fuel injection (fuel injection in the cylinder # 5 of the second cylinder group). For this reason, the drop in fuel pressure after the first fuel injection is performed becomes large as shown in FIG. 7B, and the fuel pressure is required to properly perform the fuel injection in the next fuel injection. There is a high possibility of shortage. Accordingly, the first target value Pt1 of this embodiment is set to a value larger than that of the first embodiment so that the above-described fuel pressure shortage does not occur. Further, the second target value Pt2 of this embodiment is set to a value smaller than the first target value Pt1, as shown in FIG. 7C, as in the first embodiment. Further, regarding the second target value Pt2, when the first fuel injection in the internal combustion engine 31 after the start of the start is performed in the cylinders of the second cylinder group (cylinder # 3 in the example of FIG. 7C). The first fuel injection is set to a combustible fuel pressure, which is the minimum value that can be properly performed.

  Here, if the first fuel injection after the start of engine start is performed in the cylinders of the first cylinder group and the cylinders in the second cylinder group, a common value as the target value of the fuel pressure is respectively set. If used, in other words, if the second target value Pt2 is set equal to the first target value Pt1, the following problem occurs. In other words, when the first fuel injection after the start of the engine is performed in the cylinders of the second cylinder group, the first fuel injection is performed after the fuel pressure is increased to a uselessly large value in view of properly performing the fuel injection. As a result, the wasteful increase in the fuel pressure is further increased. Then, the start of the first fuel injection is further delayed due to the increase in the useless increase in the fuel pressure.

  However, the second target value Pt2 is set to a combustible fuel pressure that is a value smaller than the first target value Pt1 and that is the minimum value at which the first fuel injection can be appropriately performed. Thus, the above-described unnecessary increase in fuel pressure is reduced as much as possible. As a result, the occurrence of the above-mentioned problem that the first fuel injection in the cylinders of the second cylinder group is further delayed is suppressed.

In this embodiment, in addition to the effects (1) to (4) in the first embodiment, the following effects are obtained.
(5) When the pumping stroke of the high-pressure fuel pump 4 is set as described above, the first fuel is injected when the first fuel injection in the internal combustion engine 31 after the start of the start is performed in the cylinders of the first cylinder group. Since the drop in fuel pressure after injection is large, the first target value Pt1 is set to a larger value than in the first embodiment. Under such circumstances, if the second target value Pt2 is set equal to the first target value Pt1, the first fuel injection after the start of engine start is performed in the cylinders of the second cylinder group. In addition, a wasteful increase in the fuel pressure when the first fuel injection is performed after the fuel pressure is increased to a large value unnecessarily becomes larger. Then, since the wasteful increase in the fuel pressure is further increased as described above, the start of the first fuel injection is further delayed. However, the occurrence of such a problem is suppressed by setting the second target value Pt2 to be smaller than the first target value Pt1 as described above.

[Other Embodiments]
In addition, each said embodiment can also be changed as follows, for example.
-The weight loss coefficient K may be a fixed value. In this case, it is preferable to fix the reduction coefficient K to an optimum value less than “1.0” determined by experiments or the like.

-It is not always necessary to perform the fuel injection amount reduction correction by the reduction coefficient K.
Regarding the first target value Pt1, when the first fuel injection in the internal combustion engine 31 after the start of the start is performed in the cylinders of the first cylinder group, the fuel pressure is changed to the next fuel injection after the first fuel injection. It may be set to a minimum value that does not become a value that is insufficient for proper fuel injection at the timing (fuel injection timing in the cylinders of the second cylinder group). If the first target value Pt1 is set in this way, the first fuel injection can be started when the first fuel injection in the internal combustion engine 31 after the start of the start is performed in the cylinders of the first cylinder group. While performing as early as possible, it becomes possible to avoid that the next fuel injection cannot be performed properly.

  Regarding the second target value Pt2, when the first fuel injection in the internal combustion engine 31 is performed in the cylinders of the second cylinder group after the start of the start, the minimum value that can properly perform the fuel injection However, it is not always necessary to set such a minimum value, and it may be set to a value larger than the minimum value and smaller than the first target value Pt1. In this case, the same effect as (1) in the first embodiment can be obtained.

  A cam of a cam 6 for driving the high-pressure fuel pump 4 so as to perform a pressure-feed stroke of the high-pressure fuel pump 4 every time the fuel injection timing is reached twice in an internal combustion engine of a type other than the V-type 6-cylinder The present invention may be applied to an internal combustion engine in which the number of peaks is adjusted.

BRIEF DESCRIPTION OF THE DRAWINGS Schematic which shows the fuel supply apparatus of 1st Embodiment, and the internal combustion engine to which the apparatus is applied. The timing chart which shows transition of the plunger lift amount of a high pressure fuel pump with respect to the change of a cam angle. (A)-(d) is the time which shows the change mode with the passage of time of the fuel pressure after the start of the start of the internal combustion engine 31, and the mode of switching between the pumping stroke and the suction stroke in the high-pressure fuel pump 4 with respect to the change of the crank angle. chart. (A)-(c) is the time which shows the change mode with the time passage of the fuel pressure after the start of the start of the internal combustion engine 31, and the mode of switching between the pumping stroke and the suction stroke in the high-pressure fuel pump 4 with respect to the change of the crank angle. chart. The flowchart which shows the execution procedure of the fuel-injection control of the internal combustion engine from the start start to independent operation start (start completion). The graph which shows transition with respect to the change of the fuel pressure about the reduction | decrease coefficient used for the reduction | decrease correction | amendment of the fuel injection quantity in the first fuel injection after the engine starting start. (A)-(c) is the mode of switching between the pumping stroke and the suction stroke of the high-pressure fuel pump 4 with respect to the change of the crank angle in the second embodiment, and the passage of time of the fuel pressure after the start of the internal combustion engine 31. A time chart showing the accompanying changes.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Fuel tank, 2 ... Feed pump, 3 ... Fuel injection valve, 4 ... High pressure fuel pump, 5 ... Exhaust camshaft, 6 ... Cam, 7 ... Coil spring, 8 ... Plunger, 9 ... Cylinder, 10 ... Pressure chamber , 11 ... suction passage, 12 ... discharge passage, 13 ... delivery pipe, 14 ... electromagnetic spill valve, 15 ... electromagnetic solenoid, 16 ... check valve, 17 ... coil spring, 18 ... electronic control device (correction means), 19 ... fuel pressure Sensor 20, crank position sensor 21, cam position sensor 22 water temperature sensor 31 internal combustion engine 32 combustion chamber 33 crankshaft

Claims (5)

A fuel supply device for an internal combustion engine that performs fuel injection from a fuel injection valve in each cylinder when the fuel injection timing of each cylinder comes when the crankshaft rotates after the engine starts. A high-pressure fuel pump that is driven by a cam that rotates with rotation to repeat the suction stroke and the pressure-feed stroke, and that the pressure-feed stroke is performed once every time the fuel injection timing is reached twice, and the pressure-feed stroke of the high-pressure fuel pump A delivery pipe that stores high-pressure fuel discharged from the pump and distributes the fuel to the fuel injection valve of each cylinder, and until the fuel pressure in the delivery pipe rises to reach a target value from the start of the engine An internal combustion engine that prohibits fuel injection from a fuel injection valve and permits fuel injection from the fuel injection valve on condition that the fuel pressure has reached the target value In the fuel supply apparatus,
For each cylinder, when the fuel injection timing is reached, the period of the pumping stroke of the high-pressure fuel pump between the current fuel injection timing and the previous fuel injection timing is the current fuel injection timing and the next fuel injection timing. The first cylinder group that is longer than the timing of the pumping stroke of the high-pressure fuel pump between the timing and the high-pressure fuel between the current fuel injection timing and the previous fuel injection timing when the fuel injection timing is reached The period of the pumping stroke of the pump is divided into a second cylinder group that is shorter than the period of the pumping stroke of the high-pressure fuel pump between the current fuel injection timing and the next fuel injection timing, and the rotation of the crankshaft Accordingly, the cylinders of the first cylinder group and the cylinders of the second cylinder group alternately reach the fuel injection timing. It is those,
When the fuel injection timing comes after the start of the engine start, if the cylinder that has reached the fuel injection timing is a cylinder of the first cylinder group, the fuel pressure in the delivery pipe has risen above the first target value. If fuel injection from the fuel injection valve of the cylinder is permitted on the condition that the cylinders that have reached the fuel injection timing are the second cylinder group, the fuel pressure has increased to a second target value or more. On the condition that fuel injection from the fuel injection valve of the cylinder is permitted,
The fuel for an internal combustion engine, wherein the first target value and the second target value are set such that the second target value is smaller than the first target value. Feeding device. Regarding the cylinders of the first cylinder group, when the cylinders have reached the fuel injection timing, there is a pumping stroke of the high-pressure fuel pump between the current fuel injection timing and the previous fuel injection timing. There is no pumping stroke of the high-pressure fuel pump between the fuel injection timing and the next fuel injection timing,
Regarding the cylinders of the second cylinder group, when the cylinders have reached the fuel injection timing, there is no pumping stroke of the high-pressure fuel pump between the current fuel injection timing and the previous fuel injection timing. 2. The fuel supply device for an internal combustion engine according to claim 1, wherein a pressure-feeding stroke of the high-pressure fuel pump exists between the fuel injection timing and the next fuel injection timing. Regarding the first target value, after the start of the engine starts, the cylinders of the first cylinder group reach the fuel injection timing, and after the fuel injection from the first fuel injection valve after the start of the start of the internal combustion engine is performed, The fuel pressure that has decreased with the fuel injection is set to be a value that can properly perform fuel injection from the fuel injection valve,
With respect to the second target value, after the start of the engine starts, the cylinders of the second cylinder group reach the first fuel injection timing in the internal combustion engine, and the fuel injection from the first fuel injection valve after the start of the internal combustion engine starts. The fuel supply device for an internal combustion engine according to claim 1 or 2, wherein the fuel injection device is set to a minimum value at which fuel injection can be properly performed. The fuel supply device for an internal combustion engine according to any one of claims 1 to 3,
When the cylinder in which fuel is injected first after the start of the engine is the cylinder of the first cylinder group, it further comprises correction means for correcting the amount of fuel injection in the first fuel injection to decrease. Fuel supply device. When the first fuel injection after the start of engine start is performed in the cylinders of the first cylinder group, the correction means corrects when the fuel injection amount is corrected to decrease as the fuel pressure at that time is smaller. The fuel supply device for an internal combustion engine according to claim 4, wherein the amount is increased.

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