JP4124097B2 - Fuel injection device for internal combustion engine - Google Patents

Description

  The present invention relates to a fuel injection device for an internal combustion engine that includes a fuel injection valve for in-cylinder injection and a fuel injection valve for intake port injection.

In-cylinder injection fuel injection valve for injecting fuel into the combustion chamber and intake port injection fuel injection valve for injecting fuel into the intake port, and in-cylinder injection and intake port injection according to operating conditions There is known a fuel injection device that executes by switching (see, for example, Patent Document 1).
Japanese Patent Laid-Open No. 7-103048 (page 2-3, FIG. 1)

  However, when the intake port injection is performed by the intake port injection fuel injection valve, the internal mechanism of the high-pressure pump, for example, the plunger continues to reciprocate due to the rotation of the internal combustion engine. Since it is not made, the function as a high pressure pump is unnecessary. For this reason, the high-pressure pump only repeats suction and return of low-pressure fuel from the low-pressure fuel path into the high-pressure chamber.

  When the high-pressure pump repeats the suction and the suck-back of the low-pressure fuel in this way, fuel pressure pulsation occurs on the low-pressure fuel side. Therefore, for example, a cylinder in which fuel is injected from a fuel injection valve for intake port injection at a phase where the pressure is high even in fuel pressure pulsation is injected more than a cylinder in which fuel is injected at a phase of low pressure. Become. As a result, the fuel injection amount varies between the cylinders, resulting in a difference in output torque between the cylinders. Therefore, in a fuel supply system that performs intake port injection and in-cylinder injection, if the fuel pressure pulsation caused by the state of the high-pressure pump is not taken into account, torque fluctuations occur between the cylinders, resulting in rotational fluctuations of the internal combustion engine. .

  An object of the present invention is to suppress variation in fuel injection amount between cylinders during intake port injection in an internal combustion engine having a fuel supply system that performs intake port injection and in-cylinder injection.

In the following, means for achieving the above object and its effects are described.
A fuel injection device for an internal combustion engine according to claim 1, wherein an intake port injection fuel injection valve injects fuel into each intake port of a plurality of cylinders and an in-cylinder injection fuel injects fuel directly into each combustion chamber of a plurality of cylinders. A low-pressure fuel pressurized by a low-pressure pump is supplied to the intake port injection fuel injection valve, and the low-pressure fuel is pressurized by a high-pressure pump to the in-cylinder injection fuel injection valve as a high-pressure fuel. A fuel injection device for an internal combustion engine having a fuel supply system for supplying the low pressure fuel to the low pressure fuel due to a state of the high pressure pump during operation of the internal combustion engine for injecting fuel from the intake port injection fuel injection valve Low pressure fuel injection timing for adjusting the injection timing of the low pressure fuel so that the timing at which the fuel pressure pulsates at the same fuel pressure is within the low pressure fuel injection period for each cylinder Characterized by comprising the section means.

  The low-pressure fuel injection timing adjusting means adjusts the low-pressure fuel injection timing so that the same fuel pressure in the fuel pressure pulsation is within the low-pressure fuel injection period for each cylinder. For this reason, it becomes possible to inject fuel from the fuel injection valve for intake port injection at the same level of fuel pressure for each cylinder.

Therefore, variation in the fuel injection amount between the cylinders at the time of intake port injection is suppressed.
The fuel injection device for an internal combustion engine according to claim 2, wherein an intake port injection fuel injection valve for injecting fuel into an intake port of each cylinder of the internal combustion engine having a plurality of banks, and the intake port provided for each bank A low-pressure fuel distribution pipe in which fuel injection valves for injection are arranged, and a low-pressure fuel pressurized by a low-pressure pump is supplied to the low-pressure fuel distribution pipe and the low-pressure fuel is pressurized by a high-pressure pump. A fuel supply system for supplying fuel to an in-cylinder fuel injection valve that directly injects fuel into the combustion chamber of each cylinder as a fuel injection system for an internal combustion engine, from the high-pressure pump to the low-pressure fuel distribution pipes The shape of the fuel pressure pulsation transmission path of the low pressure fuel is set so that the fuel pressure pulsation generated in the low pressure fuel due to the state of the high pressure pump reaches the low pressure fuel distribution pipes in the same phase. And wherein the are.

  In the case of an internal combustion engine having a plurality of banks, if there is a shift in the phase of the fuel pressure pulsation of the low pressure fuel to each low pressure fuel distribution pipe, the phase shift of the fuel pressure pulsation is caused by a change in the rotational speed of the internal combustion engine. Since the degree also changes, variation in the fuel injection amount between the cylinders due to the difference in banks tends to occur.

  However, in the present invention, the shape of the fuel pressure pulsation transmission path of the low-pressure fuel from the high-pressure pump to each low-pressure fuel distribution pipe is such that the fuel pressure pulsation generated in the low-pressure fuel due to the state of the high-pressure pump is in the same phase. Is set to reach. As a result, there is no phase shift of fuel pressure pulsation between banks even if the internal combustion engine speed changes, and intake port injection control under the same fuel pressure is facilitated. Variations in the fuel injection amount can be easily suppressed. As a result, the variation in the fuel injection amount between the cylinders at the time of intake port injection as a whole internal combustion engine can be easily suppressed.

  According to a third aspect of the present invention, there is provided a fuel injection device for an internal combustion engine according to the second aspect, wherein a length and a diameter of a fuel pressure pulsation transmission path of low pressure fuel from the high pressure pump to the low pressure fuel distribution pipes are formed to be the same. It is characterized by being.

  Since the length and diameter of the fuel pressure pulsation transmission path of the low pressure fuel from the high pressure pump to each low pressure fuel distribution pipe are the same, the fuel pressure pulsation in exactly the same state reaches each low pressure fuel distribution pipe. become. For this reason, intake port injection control under the same fuel pressure is facilitated, and variations in the fuel injection amount during intake port injection between banks can be easily suppressed.

  A fuel injection device for an internal combustion engine according to claim 4, wherein, in operation of the internal combustion engine for injecting fuel from the intake port injection fuel injection valve, the low pressure is caused by a state of the high pressure pump. Low pressure fuel injection timing adjusting means for adjusting the injection timing of the low pressure fuel so that the timing when the fuel pressure pulsation generated in the fuel becomes the same fuel pressure is within the injection period of the low pressure fuel for each cylinder; Features.

  Thus, even in the internal combustion engine having a plurality of banks, the low-pressure fuel injection timing adjusting means adjusts the low-pressure fuel so that the timing at which the fuel pressure pulsates at the same fuel pressure is within the low-pressure fuel injection period for each cylinder. The injection timing is adjusted. For this reason, it becomes possible to inject fuel from the fuel injection valve for intake port injection at the same level of fuel pressure for each cylinder.

Therefore, the variation in the fuel injection amount between the cylinders at the time of intake port injection is further effectively suppressed.
The fuel injection device for an internal combustion engine according to claim 5, wherein the low pressure fuel injection timing adjusting means has the same phase timing of fuel pressure pulsation within the injection period of the low pressure fuel for each cylinder. The injection timing of the low-pressure fuel is adjusted as follows.

  In this way, the low pressure fuel injection timing adjusting means adjusts the low pressure fuel injection timing so that the same phase timing of the fuel pressure pulsation is within the low pressure fuel injection period for each cylinder, thereby achieving the same fuel pressure. The timing can be set within the injection period of low-pressure fuel for each cylinder.

  The fuel injection device for an internal combustion engine according to claim 6, wherein the low-pressure fuel injection timing adjusting means is configured such that the timing at which the fuel pressure pulsation generated in the low-pressure fuel becomes the same fuel pressure is set in each cylinder. The low-pressure fuel injection timing is adjusted so as to be in the middle of the low-pressure fuel injection period.

  As described above, the low pressure fuel injection timing adjustment means makes the timing at which the fuel pressure pulsates in the low pressure fuel become the same fuel pressure at the center of the low pressure fuel injection period for each cylinder, thereby achieving higher accuracy. Variations in the fuel injection amount between the cylinders can be suppressed.

  The fuel injection device for an internal combustion engine according to claim 7, wherein the low pressure fuel injection timing adjusting means is configured such that the timing at which the fuel pressure pulsation generated in the low pressure fuel becomes the center is the low pressure for each cylinder. The injection timing of the low-pressure fuel is adjusted so as to be in the center of the fuel injection period.

  Even if they are not in the same phase, if the fuel pressure pulsation is in the center, the fuel pressure at the time of intake port injection for each cylinder will be the same, and therefore variations in the fuel injection amount among the cylinders can be suppressed.

[Embodiment 1]
FIG. 1 is a schematic configuration diagram of an internal combustion engine and a fuel supply system to which the above-described fuel injection device is applied. Here, the internal combustion engine is a gasoline engine (hereinafter referred to as an engine) 2 and is a V-type 6-cylinder engine provided with two banks 2a and 2b. Each bank 2a, 2b is composed of three cylinders, # 1 cylinder 4, # 3 cylinder 8 and # 5 cylinder 12 are formed in the left bank 2a, and # 2 cylinder 6, # 4 cylinder 10 are formed in the right bank 2b. And # 6 cylinder 14 is formed.

  The left bank 2a is provided with in-cylinder injection fuel injection valves 4a, 8a, and 12a for injecting fuel directly into the combustion chamber for each of the cylinders 4, 8, and 12, and high pressure fuel is supplied from the high pressure fuel distribution pipe 16. ing. Furthermore, in the left bank 2a, intake port injection fuel injection valves 4b, 8b, 12b for injecting fuel into the intake ports are provided in the intake ports of the cylinders 4, 8, 12 so that the low pressure fuel is supplied from the low pressure fuel distribution pipe 18. Have been supplied.

  Similarly, the right bank 2b is provided with in-cylinder injection fuel injection valves 6a, 10a, and 14a for injecting fuel directly into the combustion chamber for each of the cylinders 6, 10, and 14, and from the high-pressure fuel distribution pipe 20 to a high pressure. Fuel is being supplied. Further, in the right bank 2b, intake port injection fuel injection valves 6b, 10b, and 14b for injecting fuel into the intake ports are provided at the intake ports of the cylinders 6, 10, and 14, respectively. Have been supplied.

Fuel supply to each distribution pipe 16, 18, 20, 22 is performed by a feed pump 24 as a low pressure pump and a high pressure fuel pump 26 as a high pressure pump.
The high-pressure fuel pump 26 includes a triangular pump cam 30 attached to an intake camshaft 28 of the engine 2, a cylinder 32, and a plunger 34 that reciprocates within the cylinder 32. The high-pressure fuel pump 26 includes a portion formed by the cylinder 32 and the plunger 34 as a pressurizing chamber 36, and includes a solenoid opening / closing valve 40 at a fuel introduction port 38 opened to the pressurizing chamber 36. Yes.

  During the intake stroke of the high-pressure fuel pump 26, fuel is supplied from the fuel tank 44 to the pressurizing chamber 36 by the feed pump 24 through the fuel introduction port 38 and the low-pressure fuel path 42. Of the low-pressure fuel pumped up by the feed pump 24, the low-pressure fuel that has not been drawn into the high-pressure fuel pump 26 is returned to the fuel tank 44 via the relief valve 46. During the pressurization stroke of the high-pressure fuel pump 26, the high-pressure fuel pressurized in the pressurizing chamber 36 pushes the check valve 48 open. Then, the high pressure fuel is supplied to the high pressure fuel distribution pipes 16 and 20 through the high pressure fuel passage 50 branched into two. Thus, high-pressure fuel capable of fuel injection can be supplied into the combustion chamber of the engine 2 to the in-cylinder fuel injection valves 4a, 6a, 8a, 10a, 12a, and 14a. When excessive fuel that is not used for fuel injection is generated in the distribution pipes 16 and 20, the fuel is returned to the fuel tank 44 through the relief valve 52.

  The low pressure fuel supplied from the feed pump 24 is supplied from the low pressure fuel path 42 to the low pressure fuel distribution pipes 18 and 22 through the low pressure fuel path 54. As a result, the low-pressure fuel for fuel injection into the intake port of the engine 2 can be supplied to each intake port injection fuel injection valve 4b, 6b, 8b, 10b, 12b, 14b. Here, the low-pressure fuel passage 54 is branched into two branch passages 54a and 54b for supplying low-pressure fuel to the two low-pressure fuel distribution pipes 18 and 22, and these branch passages 54a and 54b have the same length and The diameter is the same.

  The metering of the high pressure fuel pumped to the high pressure fuel passage 50 side in the high pressure fuel pump 26 is performed by opening / closing drive control of the electromagnetic on / off valve 40 by an electronic control unit (hereinafter, abbreviated as “ECU”) 56. The ECU 56 is an electronic circuit mainly composed of a digital computer, and inputs various data signals from an engine speed sensor, a cam position sensor, a fuel pressure sensor for high pressure fuel, and other various sensors and switches. The ECU 56 controls the driving of the electromagnetic on-off valve 40 by executing calculations based on these detection signals and setting the timing of energization / non-energization from the power source to the electromagnetic on-off valve 40. Further, the ECU 56 performs engine control such as fuel injection control and ignition timing control. In the fuel injection control of the present embodiment, control is performed to inject fuel from the intake port injection fuel injection valves 4b to 14b to each intake port when the engine is under low load. Control is performed to inject fuel from the in-cylinder fuel injection valves 4a to 14a into the combustion chambers when the engine is heavily loaded.

  When the exciting coil 40a is energized, the electromagnetic opening / closing valve 40 moves the valve element 40b to the opposite side of the pressurizing chamber 36 against the urging force of the spring 40c, sits on the seat portion 40d, and closes the valve. . When the energization is stopped, the valve body 40b moves to the pressurizing chamber 36 side by the urging force of the spring 40c and opens away from the seat portion 40d. Thus, the electromagnetic on-off valve 40 is configured as a normally open type inner open valve.

  At the time of high-pressure fuel metering performed during in-cylinder injection control, first, when the plunger 34 is pushed down by the urging force of the push-down spring 34a by the rotation of the pump cam 30, the volume of the pressurizing chamber 36 is expanded. At this time, the exciting coil 40a is in a non-energized state and the electromagnetic on-off valve 40 is open, so that the intake stroke is started, and the low pressure fuel in the low pressure fuel path 42 is sucked into the pressurizing chamber 36. Then, when the plunger 34 is pushed up against the urging force of the spring 34 a by the rotation of the pump cam 30, the volume of the pressurizing chamber 36 is reduced, so that the fuel in the pressurizing chamber 36 is pressurized and the fuel introduction port 38. To return to the low-pressure fuel path 42 side. However, during this pressurization stroke, the exciting coil 40a is energized and the electromagnetic on-off valve 40 is closed, so that the fuel introduction port 38 is closed and the fuel in the pressurization chamber 36 is pressurized. As a result, the high-pressure fuel in the pressurizing chamber 36 pushes open the check valve 48 and flows into the high-pressure fuel distribution pipes 16 and 20 via the high-pressure fuel passage 50. The high-pressure fuel is metered by the energization timing control of the exciting coil 40a during the pressurization stroke.

  During the intake port injection control by the intake port injection fuel injection valves 4b to 14b described above, the high pressure fuel in the high pressure fuel distribution pipes 16 and 20 is not consumed. It becomes unnecessary. Therefore, the ECU 56 performs control while maintaining the exciting coil 40a in a non-energized state and opening the electromagnetic on-off valve 40. At this time, the pump cam 30 drives the plunger 34 by the rotation of the intake camshaft 28 of the engine 2, but the fuel inlet 38 remains open. For this reason, even if the plunger 34 moves in the direction of reducing the volume in the pressurizing chamber 36, the fuel returns from the fuel introduction port 38 to the low-pressure fuel path 42 side. The high pressure fuel is not pumped to the high pressure fuel distribution pipes 16 and 20 side.

  Thus, at the time of intake port injection control, the high-pressure fuel pump 26 does not function as a pump, and an intake state in which fuel is sucked into the pressurizing chamber 36 from the low-pressure fuel path 42 side and a low-pressure fuel path 42 from the pressurizing chamber 36. The return state in which the fuel is discharged to the side is repeated. This causes a low pressure fuel pressure pulsation in the low pressure fuel path 42. Since the pump cam 30 rotates once per engine cycle, three cycles of pulsation occur per engine cycle.

  The low pressure fuel pressure pulsation is transmitted to the low pressure fuel distribution pipes 18 and 22 by the branch passages 54a and 54b of the low pressure fuel passage 54. As described above, the two branch passages 54a and 54b have the same length and the same diameter. Therefore, the phase of the low pressure fuel pressure pulsation is exactly the same in the two low pressure fuel distribution pipes 18 and 22. For example, as shown in FIG. 2, low pressure fuel pressure pulsations having the same phase and amplitude occur in the two low pressure fuel distribution pipes 18 and 22.

  Here, at the time of intake port injection, the ECU 56 for each of the # 1 cylinder 4, the # 3 cylinder 8 and the # 5 cylinder 12 has a fuel injection period in a phase where the crank angle becomes a peak of fuel pressure pulsation generated at intervals of 240 °. The fuel injection timing is set so that the center of The fuel injection timing is set by mapping the engine speed, the fuel injection amount, and the fuel injection timing in advance through experiments and calculations, and using this map, This is realized by setting the fuel injection timing based on the engine speed and the fuel injection amount.

  The intake port injection periods for # 2 cylinder 6, # 4 cylinder 10 and # 6 cylinder 14 are made to coincide with those of # 1 cylinder 4, # 3 cylinder 8 and # 5 cylinder 12, respectively. As a result, as shown in FIG. 2, the timing of the low pressure fuel is such that the fuel pressure pulsation generated in the low pressure fuel has the same fuel pressure (here, the peak fuel pressure) within the low pressure fuel injection period for each cylinder. The injection timing is adjusted.

In the configuration described above, the ECU 56 corresponds to a low-pressure fuel injection timing adjusting unit.
According to the first embodiment described above, the following effects can be obtained.
(I). In the present embodiment, the fuel pressure pulsation transmission path of the low pressure fuel from the high pressure fuel pump 26 to the low pressure fuel distribution pipe 18 of the left bank 2a, and the low pressure fuel from the high pressure fuel pump 26 to the low pressure fuel distribution pipe 22 of the right bank 2b. This is different from the fuel pressure pulsation transmission path of the branch passages 54a and 54b. However, the low-pressure fuel path 42 and the low-pressure fuel passage 54 other than this are common as paths. As described above, the two branch passages 54a and 54b have the same length and the same diameter. Therefore, the fuel pressure pulsation transmission paths of the low pressure fuel from the high pressure fuel pump 26 to the low pressure fuel distribution pipes 18 and 22 have the same length and the same diameter.

  As a result, even if the engine speed changes, the fuel pressure pulsation state is always the same with no phase shift between the banks 2a and 2b with respect to the intake port injection fuel injection valves 4b to 14b. Therefore, as shown in the graph of FIG. 2, the ECU 56 includes the # 1 cylinder 4 and the # 2 cylinder 6, the # 3 cylinder 8 and the # 4 cylinder 10, and the # 5 cylinder 12 and the # 6 cylinder 14. By simultaneously performing the intake port injection, intake port injection control under the same fuel pressure is facilitated. This makes it possible to easily suppress the variation in the fuel injection amount during the intake port injection between the banks 2a and 2b, and to easily suppress the variation in the fuel injection amount between the cylinders 4 to 14 during the intake port injection for the engine 2 as a whole. it can.

  (B). The ECU 56 performs injection control so that the same phase timing of fuel pressure pulsation (here, the timing at which the peak fuel pressure is reached) is within the low pressure fuel injection period for each of the cylinders 4 to 14 and at the center of the injection period. ing. As a result, the variation in the fuel injection amount between the cylinders can be suppressed with high accuracy.

[Embodiment 2]
In the present embodiment, as shown in FIG. 3, the ECU 56 makes the center of the low pressure fuel injection period for each of the cylinders 4 to 14 coincide with the pulsation center generated in the fuel pressure pulsation at every crank angle of 120 °. The fuel injection timing is set as described in the first embodiment. That is, the relationship between the engine speed and the fuel injection amount and the fuel injection timing at which the center of the injection period comes to the center of the pulsation is obtained and mapped in advance through experiments and calculations, and this map is used during actual engine operation. This can be realized by setting the fuel injection timing based on the engine speed and the fuel injection amount. The other configuration is the same as that of the first embodiment.

According to the second embodiment described above, the following effects can be obtained.
(I). The effect (a) of the first embodiment is produced.
(B). Even if the fuel pressure pulsation is not in the same phase, if the fuel pressure pulsation is in the middle, the fuel pressure at the time of intake port injection to each cylinder 4-14 will be the same, so variation in the fuel injection amount between the cylinders 4-14 will be suppressed. be able to.

  Moreover, since the pump cam 30 of the high-pressure fuel pump 26 rotates once for one cycle of the engine, the center of the fuel pressure pulsation is generated six times per cycle as shown in FIG. 3, and at equal intervals (120 °) as the crank angle. . Therefore, the timing at the center of the fuel pulsation can more appropriately correspond to the fuel injection period of each cylinder 4-14. When the intake port injection timing is set in this way, the air-fuel mixture having the same fuel vaporization state is sucked into the combustion chamber from the intake ports of the respective cylinders 4 to 14, and the combustion state is also the same. This is more effective in preventing torque fluctuation between cylinders during port injection.

[Embodiment 3]
This embodiment is an example for an in-line 6-cylinder engine 102 as shown in FIG. Here, one high-pressure fuel distribution pipe 116 and one low-pressure fuel distribution pipe 118 are provided. The high-pressure fuel distribution pipe 116 is provided with in-cylinder fuel injection valves 104a, 106a, 108a, 110a, 112a, 114a for six cylinders, and high-pressure fuel is distributed and supplied. The low-pressure fuel distribution pipe 118 is provided with fuel injection valves 104b, 106b, 108b, 110b, 112b, 114b for six cylinders for distributing and supplying low-pressure fuel. The configuration on the side for pumping fuel to the high-pressure fuel distribution pipe 116 and the low-pressure fuel distribution pipe 118 side is the same as that in the first embodiment, and is therefore denoted by the same reference numeral.

  Here, since there is one high-pressure fuel distribution pipe 116 and one low-pressure fuel distribution pipe 118, both the high-pressure fuel passage 50 and the low-pressure fuel passage 54 are not branched. Further, the firing order of the six cylinders 104, 106, 108, 110, 112, 114 is set as # 1 cylinder 104 → # 5 cylinder 112 → # 3 cylinder 108 → # 6 cylinder 114 → # 2 cylinder 106 → # 4 cylinder 110. ing. Therefore, during the intake port injection, the ECU 156 sets the fuel injection timing so that the center of the injection period comes at a crank angle of 240 ° intervals for the # 1 cylinder 104, the # 3 cylinder 108, and the # 2 cylinder 106. Yes. The fuel injection timing can be set based on the engine speed and the fuel injection amount during actual engine operation using the map as described in the first embodiment.

  The intake port injection periods for # 5 cylinder 112, # 6 cylinder 114, and # 4 cylinder 110 are made to coincide with those of # 1 cylinder 104, # 3 cylinder 108, and # 2 cylinder 106, respectively. As a result, as shown in FIG. 5, the fuel injection from the intake port injection fuel injection valves 104b to 114b is performed at the same fuel pressure timing on the low pressure fuel pressure pulsation for all the cylinders 104 to 114.

In the configuration described above, the ECU 156 corresponds to a low-pressure fuel injection timing adjusting unit.
According to the third embodiment described above, the following effects can be obtained.
(I). Also for one low pressure fuel distribution pipe 118, the ECU 156 sets the intake port injection periods of the # 1 cylinder 104, # 2 cylinder 106, and # 3 cylinder 108 to the same phase of the fuel pressure pulsation. Further, the intake port injection period is made to coincide with # 2 cylinder 106 for # 4 cylinder 110, # 1 cylinder 104 for # 5 cylinder 112, and # 3 cylinder 108 for # 6 cylinder 114. As a result, fuel can be injected to all cylinders 104 to 114 at the same fuel pressure as fuel pressure pulsation.

Therefore, also in the inline engine 102, variation in the fuel injection amount between the cylinders 104 to 114 at the time of intake port injection is suppressed.
(B). The effect (b) of the first embodiment is produced.

[Embodiment 4]
In the present embodiment, the hardware configuration is as shown in FIG. 4, but as shown in FIG. 6, the ECU 156 has a low pressure for each of the cylinders 104 to 114 at the center of the pulsation that occurs in the fuel pressure pulsation at every crank angle of 120 °. The center of the fuel injection period is made to coincide. The other configuration is the same as that of the third embodiment.

According to the fourth embodiment described above, the following effects can be obtained.
(I). The effect (b) of the second embodiment is produced.
[Embodiment 5]
The present embodiment is as shown in FIG. Here, since the engine 2, the feed pump 24, and the high-pressure fuel pump 26 have the same configuration as in the first embodiment, the same reference numerals are given. The low-pressure fuel passage 254 supplies low-pressure fuel to the low-pressure fuel distribution pipe 18 on the left bank 2a side, and the branch passage 254a branched from the low-pressure fuel passage 254 supplies low-pressure fuel to the low-pressure fuel distribution pipe 22 on the right bank 2b side. is doing. Therefore, since the shape, in particular, the length of the fuel pressure pulsation transmission path differs between the left and right banks 2a and 2b, the low pressure fuel pressure pulsation on the left bank 2a side and the low pressure fuel pressure pulsation on the right bank 2b side as shown in FIG. The phases do not match, and the degree of mismatch of the low-pressure fuel pressure pulsation varies depending on the engine speed.

  Here, the ECU 256 sets the fuel injection timing so that the center of the injection period comes to the peak phase of the fuel pressure pulsation based on the map as described in the first embodiment. However, the maps for # 1 cylinder 4, # 3 cylinder 8 and # 5 cylinder 12 and the maps for # 2 cylinder 6, # 4 cylinder 10 and # 6 cylinder 14 correspond to the phase shift of the low pressure fuel pressure pulsation. Different maps are used.

  As a result, as shown in FIG. 8, the fuel pressure pulsation reaches a peak phase in the center of the intake port injection period in all the cylinders 4 to 14, so that the same fuel pressure is applied to all the cylinders 4 to 14 to the intake port. Fuel is injected.

In the configuration described above, the ECU 256 corresponds to a low-pressure fuel injection timing adjusting unit.
According to the fifth embodiment described above, the following effects can be obtained.
(I). Even if there is a deviation in fuel pressure pulsation between the banks 2a and 2b, the ECU 256 switches the map for each bank 2a and 2b to calculate the fuel injection timing, so that the same fuel is obtained in any cylinder 4-14. It can be injected with pressure. Therefore, variation in the fuel injection amount between the cylinders 4 to 14 at the time of intake port injection can be suppressed.

[Other embodiments]
(A). In the first, third, and fifth embodiments, the fuel pressure peak is set so that the peak of the fuel pressure is at the center of the intake port fuel injection period for all the cylinders. If so, timing other than the fuel pressure peak may be used. For example, it may be the bottom of the fuel pressure, or may be an intermediate phase between the fuel pressure peak and the fuel pressure bottom.

  Further, the same fuel pressure state may be set at a timing other than the center of the intake port fuel injection period. For example, it may be at the start or end of the intake port fuel injection period. Moreover, the middle of these may be sufficient.

  (B). A pulsation damper for reducing the low pressure fuel pressure pulsation may be attached to the low pressure fuel passage in the configuration of each of the embodiments. In particular, when one pulsation damper is attached, the low pressure fuel passage 54 is branched when the fuel pressure pulsation phases are matched between the left bank 2a and the right bank 2b as in the first and second embodiments. By setting the branching portion to be divided into the passages 54a and 54b, it is possible to maintain the coincidence state of the fuel pressure pulsation phase.

(C). Although the high-pressure fuel pump is a spill metering type, it may be a suction metering type high-pressure fuel pump that meteres the amount of fuel sucked when fuel is sucked into the pressurized chamber.
(D). In each of the above-described embodiments, the description has been given of the six-cylinder engine. However, the present invention can be applied to a multi-cylinder engine having less than six cylinders and a multi-cylinder engine having more than six cylinders.

1 is a schematic configuration diagram of an engine and a fuel supply system as a first embodiment. 6 is a graph showing the control content of intake port injection executed by the ECU according to the first embodiment. 6 is a graph showing the control content of intake port injection executed by the ECU according to the second embodiment. FIG. 4 is a schematic configuration diagram of an engine and a fuel supply system as a third embodiment. FIG. 9 is a graph showing the control content of intake port injection executed by the ECU according to the third embodiment. FIG. FIG. 9 is a graph showing the control content of intake port injection executed by the ECU of the fourth embodiment. FIG. FIG. 6 is a schematic configuration diagram of an engine and a fuel supply system as a fifth embodiment. FIG. 9 is a graph showing the control content of intake port injection executed by the ECU of the fifth embodiment. FIG.

Explanation of symbols

  2 ... Engine, 2a ... Left bank, 2b ... Right bank, 4, 6, 8, 10, 12, 14 ... Cylinder, 4a, 8a, 12a, 6a, 10a, 14a ... Fuel injection valve for in-cylinder injection, 4b, 8b, 12b, 6b, 10b, 14b ... fuel injection valve for intake port injection, 16, 20 ... high pressure fuel distribution pipe, 18, 22 ... low pressure fuel distribution pipe, 24 ... feed pump, 26 ... high pressure fuel pump, 28 ... intake air Camshaft, 30 ... Pump cam, 32 ... Cylinder, 34 ... Plunger, 34a ... Spring, 36 ... Pressurization chamber, 38 ... Fuel inlet, 40 ... Electromagnetic on-off valve, 40a ... Excitation coil, 40b ... Valve body, 40c ... Spring 40d ... Seat part, 42 ... Low pressure fuel path, 44 ... Fuel tank, 46 ... Relief valve, 48 ... Check valve, 50 ... High pressure fuel passage, 52 ... Relief valve, 54 ... Low pressure fuel passage, 4a, 54b ... branch passage, 56 ... ECU, 102 ... engine, 104, 106, 108, 110, 112, 114 ... cylinder, 104a, 106a, 108a, 110a, 112a, 114a ... fuel injection valve for in-cylinder injection, 104b 106b, 108b, 110b, 112b, 114b ... fuel injection valve for intake port injection, 116 ... high pressure fuel distribution pipe, 118 ... low pressure fuel distribution pipe, 156 ... ECU, 254 ... low pressure fuel passage, 254a ... branch passage, 256 ... ECU.

Claims (7)

Low pressure pressurized by a low pressure pump, comprising an intake port injection fuel injection valve that injects fuel into each cylinder's intake port and an in-cylinder injection fuel injection valve that directly injects fuel into each cylinder's combustion chamber A fuel injection device for an internal combustion engine comprising a fuel supply system that supplies fuel to the intake port injection fuel injection valve, pressurizes the low pressure fuel by a high pressure pump, and supplies the fuel as high pressure fuel to the in-cylinder injection fuel injection valve Because
During operation of the internal combustion engine that injects fuel from the intake port injection fuel injection valve, the timing at which the same fuel pressure is caused by the fuel pressure pulsation generated in the low pressure fuel due to the state of the high pressure pump is the low pressure for each cylinder. A fuel injection device for an internal combustion engine, comprising: a low-pressure fuel injection timing adjusting means for adjusting an injection timing of the low-pressure fuel so as to be within a fuel injection period. An intake port injection fuel injection valve that injects fuel into the intake port of each cylinder of an internal combustion engine having a plurality of banks, and a low pressure that is provided for each bank and is arranged in an array of the intake port injection fuel injection valves In-cylinder in which fuel distribution pipe and low-pressure fuel pressurized by a low-pressure pump are supplied to the low-pressure fuel distribution pipe and the low-pressure fuel is pressurized by a high-pressure pump and directly injected into the combustion chamber of each cylinder as high-pressure fuel A fuel injection device for an internal combustion engine comprising a fuel supply system for supplying to a fuel injection valve for injection,
The shape of the fuel pressure pulsation transmission path of the low pressure fuel from the high pressure pump to each of the low pressure fuel distribution pipes is such that the fuel pressure pulsation generated in the low pressure fuel due to the state of the high pressure pump is in the same phase. A fuel injection device for an internal combustion engine, wherein the fuel injection device is set to reach a pipe. 3. The fuel injection device for an internal combustion engine according to claim 2, wherein the length and the diameter in the fuel pressure pulsation transmission path of the low pressure fuel from the high pressure pump to each of the low pressure fuel distribution pipes are formed to be the same. 4. The timing according to claim 2 or 3, wherein the same fuel pressure is caused by the fuel pressure pulsation generated in the low-pressure fuel due to the state of the high-pressure pump during operation of the internal combustion engine in which fuel is injected from the fuel injection valve for intake port injection. A fuel injection device for an internal combustion engine, comprising: low-pressure fuel injection timing adjusting means for adjusting the injection timing of the low-pressure fuel so as to be within an injection period of the low-pressure fuel for each cylinder. 5. The low pressure fuel injection timing adjusting means according to claim 1, wherein the low pressure fuel injection timing adjusting means adjusts the injection timing of the low pressure fuel so that the same phase timing of fuel pressure pulsation is within an injection period of the low pressure fuel for each cylinder. A fuel injection device for an internal combustion engine. 5. The low-pressure fuel injection timing adjusting means according to claim 1, wherein the low-pressure fuel injection timing adjusting means adjusts the fuel pressure pulsation generated in the low-pressure fuel to the same fuel pressure at the center of the low-pressure fuel injection period for each cylinder. A fuel injection device for an internal combustion engine, characterized by adjusting an injection timing of low-pressure fuel. 5. The low-pressure fuel injection timing adjusting means according to claim 1, wherein the low-pressure fuel injection timing adjusting means adjusts the low-pressure fuel so that the timing at which the fuel pressure pulsation that occurs in the low-pressure fuel becomes the center is the center of the low-pressure fuel injection period for each cylinder. A fuel injection device for an internal combustion engine, characterized by adjusting an injection timing.

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