JP2005146881A - Fuel injection device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve air fuel ratio controllability of a fuel injection device for an internal combustion engine provided with a fuel injection valve for cylinder injection and a fuel injection valve for intake port injection. <P>SOLUTION: Execution of intake port injection mode is limited to a left bank and cylinder injection is executed in a right bank S112, S114 in an intake port injection limitation zone "YES in S108" even at a time of intake port injection mode. Since variation of fuel injection quantity between the banks due to low pressure fuel pressure pulsation caused by a high pressure fuel pump becomes very small, air fuel ratio controllability for each bank is improved and air fuel ratio controllability as whole engine is improved. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a fuel injection device for an internal combustion engine provided with 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 in-cylinder injection is stopped and only the intake port injection is executed, the internal mechanism of the high-pressure pump, for example, the plunger continues to reciprocate due to the rotation of the internal combustion engine. Therefore, 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 by reciprocating movement of the plunger.

  If the high-pressure pump repeatedly sucks and returns the low-pressure fuel in this way, fuel pressure pulsation occurs on the low-pressure fuel side, and the amount of fuel injected into the intake port varies due to the influence of this fuel pressure pulsation between cylinders. May occur. In other words, in a cylinder injected with intake port at a timing when the fuel pressure becomes high due to fuel pressure pulsation, a relatively large amount of fuel is consumed even in the same fuel injection period as compared with a cylinder injected with intake port at a timing when low. It will be injected into the intake port.

  When a relative difference between the cylinders occurs in the fuel injection amount in this way, appropriate air-fuel ratio control cannot be performed for each cylinder. As a result, the air-fuel ratio cannot be appropriately controlled even in the entire internal combustion engine, and there is a risk of causing problems in exhaust emission and the like.

  The same problem also occurs in a plurality of banks, for example, a two-bank internal combustion engine such as a V-type, due to the low-pressure fuel pressure pulsation described above. Further, in the case of a multi-bank type internal combustion engine, even if the influence of fuel pressure pulsation is small in the injection timing to the intake port in each bank, the influence of fuel pressure pulsation becomes large between the banks and the intake There may be variations in the port injection amount. Therefore, there is a case where appropriate air-fuel ratio control cannot be performed for each bank. As a result, the air-fuel ratio cannot be appropriately controlled even in the entire internal combustion engine, and there is a risk of causing problems in exhaust emission and the like.

  An object of the present invention is to improve air-fuel ratio controllability in a fuel injection device for an internal combustion engine provided with a fuel injection valve for in-cylinder injection and a fuel injection valve for intake port injection.

In the following, means for achieving the above object and its effects are described.
The fuel injection device for an internal combustion engine according to claim 1 includes an intake port injection fuel injection valve that injects fuel into an intake port of each cylinder of the internal combustion engine, and an in-cylinder injection that directly injects fuel into the combustion chamber of each cylinder. The fuel injection valve and the low pressure fuel pressurized by the low pressure pump are supplied to the intake port injection fuel injection valve and the low pressure fuel is pressurized by the high pressure pump to the in-cylinder injection fuel injection valve. A fuel injection system for an internal combustion engine that executes an intake port injection mode in which fuel is injected only from the fuel injection valve for intake port injection in accordance with an operating state of the internal combustion engine. In the port injection mode, the fuel injection amount from the intake port injection fuel injection valve varies due to the fuel pressure pulsation generated by the high pressure pump in the operating state of the internal combustion engine. In a region where the fuel injection is large, the fuel injection valve is provided with intake port injection limiting means for stopping fuel injection from the fuel injection valve for intake port injection and executing fuel injection from the fuel injection valve for in-cylinder injection. .

  When the intake port injection mode is executed in a region where the variation in the fuel injection amount from the fuel injection valve for intake port injection is large due to the fuel pressure pulsation generated by the high pressure pump, the variation in the fuel injection amount among the cylinders As a result, the air-fuel ratio may not be appropriately controlled in each cylinder.

  However, the intake port injection restricting means stops the fuel injection from the intake port injection fuel injection valve even in the intake port injection mode in such a region where the variation in the fuel injection amount is large. Fuel injection from the fuel injection valve is executed. Accordingly, since the fuel pressure pulsation in the low pressure fuel does not affect the fuel injection amount, the problem of variation in the fuel injection amount among the cylinders is solved.

For this reason, the air-fuel ratio controllability for each cylinder is improved, and the air-fuel ratio controllability is improved as a whole internal combustion engine.
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 The low pressure fuel distribution pipe provided with the fuel injection valves for injection, the in-cylinder fuel injection valve for directly injecting fuel into the combustion chamber of each cylinder, and the low pressure fuel pressurized by the low pressure pump A fuel supply system that supplies the low-pressure fuel to a low-pressure fuel distribution pipe and pressurizes the low-pressure fuel with a high-pressure pump as a high-pressure fuel to the in-cylinder fuel injection valve. A fuel injection device for an internal combustion engine that executes an intake port injection mode in which fuel is injected only from a fuel injection valve for injection, the fuel pressure pulsation generated by the high-pressure pump within the operating state of the internal combustion engine Therefore, in the region where the variation in the fuel injection amount from the fuel injection valve for intake port injection is large, the intake port injection limiting means for limiting the number of banks that execute the intake port injection mode to one or less among all the banks. It is provided with.

  In the region where the variation in the fuel injection amount from the fuel injection valve for intake port injection is large due to the fuel pressure pulsation generated by the high pressure pump, the variation in the fuel injection amount between cylinders in each bank in the intake port injection mode. Even if there is no problem, there may be a large variation in fuel injection amount between banks. As a result, there is a possibility that air-fuel ratio control cannot be performed properly in each bank.

  However, the intake port injection limiting means limits the number of banks that execute the intake port injection mode to one or less in such a region where the variation in the fuel injection amount is large. Thus, even in a region where the variation in the fuel injection amount from the fuel injection valve for intake port injection is large, the variation in the fuel injection amount does not increase between banks.

  For example, if the number of banks that execute the intake port injection mode is one, the other banks are in modes other than the intake port injection mode, so the fuel pressure pulsation generated by the high-pressure pump is irrelevant, and the intake port injection between the banks is not performed. Variations in the amount of fuel injected at the end are no problem. Further, if in-cylinder injection is executed for another bank, the fuel pressure pulsation itself generated by the high-pressure pump becomes small, or the fuel pressure pulsation disappears. For this reason, the variation in the fuel injection amount between the banks is very small or completely eliminated.

  If none of the banks execute the intake port injection mode, the fuel pressure pulsation generated by the high-pressure pump is irrelevant for all the banks. For this reason, there is no problem in the variation of the fuel injection amount in the intake port injection between the banks.

For this reason, the air-fuel ratio controllability for each bank is improved, and the air-fuel ratio controllability is improved as a whole internal combustion engine.
4. The fuel injection device for an internal combustion engine according to claim 3, wherein the intake port injection restricting means is the in-cylinder injection fuel injection valve for banks other than the bank that executes the intake port injection mode. The fuel injection from is performed.

  By executing the fuel injection from the in-cylinder fuel injection valve in this way, the fuel pressure pulsation itself generated by the high-pressure pump is reduced or the fuel pressure pulsation disappears. For this reason, the variation in the fuel injection amount between the banks is very small or completely eliminated, so that the air-fuel ratio controllability for each bank is improved, and the air-fuel ratio controllability is improved as a whole internal combustion engine.

  The fuel injection device for an internal combustion engine according to claim 4, wherein, in claim 2, when the intake port injection restriction unit executes the intake port injection mode in one bank, The fuel injection from the in-cylinder injection fuel injection valve or the fuel injection is stopped.

  As described above, by performing fuel injection from the in-cylinder fuel injection valve for other banks as described above, the air-fuel ratio controllability for each bank is improved, and the air-fuel ratio controllability of the entire internal combustion engine is also improved. To do.

  When the fuel injection is stopped for the other banks, the fuel injection is only one bank in the intake port injection mode, so the fuel pressure pulsation generated by the high pressure pump is irrelevant for the other banks, and the fuel between the banks There is no variation in the injection amount. Therefore, the air-fuel ratio controllability can be improved for the entire internal combustion engine.

  6. The fuel injection device for an internal combustion engine according to claim 5, wherein the intake port injection restricting means is one or more banks when the intake port injection mode is not executed in any bank. The fuel injection from the fuel injection valve for in-cylinder injection is executed at, and the fuel injection is stopped for the other banks.

  As described above, fuel injection from the in-cylinder injection fuel injection valve is executed in some banks, and fuel injection is stopped in other banks, resulting in fuel pressure pulsation generated by the high-pressure pump. Variations in the fuel injection amount from the fuel injection valve for intake port injection are completely free from problems. For this reason, the air-fuel ratio controllability for each bank is improved, and the air-fuel ratio controllability is improved as a whole internal combustion engine.

According to a sixth aspect of the present invention, there is provided a fuel injection device for an internal combustion engine according to any one of the second to fifth aspects, wherein the internal combustion engine includes two banks.
As the internal combustion engine, an engine having two banks can be mentioned. As described in claims 2 to 5, the intake port injection restricting means limits the fuel injection for both banks, so that the air-fuel ratio for each bank. The controllability is improved, and the air-fuel ratio controllability can be improved even for the entire internal combustion engine.

  The fuel injection device for an internal combustion engine according to claim 7, wherein the intake port injection mode is executed in an operation region provided on a low load side of the internal combustion engine according to any one of claims 1 to 6. A region where the variation in the fuel injection amount from the fuel injection valve for intake port injection is large is set in a rotational speed region lower than a reference rotational speed provided therein.

  As described above, an operation region for executing the intake port injection mode is provided on the low load side, and in this operation region, the fuel injection amount from the fuel injection valve for intake port injection due to the fuel pressure pulsation generated by the high-pressure pump. It is possible to set a region where the variation in the number is large based on the reference rotational speed.

  As a result, it is possible to easily determine the region where the variation in the fuel injection amount is large, appropriately suppress the variation in the fuel injection amount between the cylinders or between the banks, and improve the air-fuel ratio controllability for each cylinder or each bank. The air-fuel ratio controllability can be improved as a whole engine.

[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, low pressure fuel for injecting fuel into the intake port of each cylinder can be supplied to the fuel injection valves 4b, 6b, 8b, 10b, 12b, and 14b for intake port injection. A branch passage 54a branches from the low pressure fuel passage 54 and supplies low pressure fuel to the low pressure fuel distribution pipe 22 side.

  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, an air-fuel ratio sensor and other various sensors and switches. ing. 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 and low speed. Control is performed to inject fuel into the combustion chambers from the internal injection fuel injection valves 4a to 14a.

  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.

  When the intake port injection control is performed by the intake port injection fuel injection valves 4b to 14b and the fuel injection from the in-cylinder injection fuel injection valves 4a to 14a is not performed, the high-pressure fuel distribution pipes 16 are provided. , 20 is not consumed, and high pressure fuel pumping to the high pressure fuel passage 50 is not required. 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 reciprocates the plunger 34 by the rotation of the intake camshaft 28 of the engine 2, but the fuel introduction port 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, when in-cylinder injection is not performed at the time of intake port injection, 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 pressurization The return state in which fuel is discharged from the chamber 36 toward the low-pressure fuel path 42 side is repeated. This causes fuel pressure pulsation in the low pressure fuel path 42. Here, since the pump cam 30 rotates once per engine cycle, three cycles of fuel pressure pulsation occur in the engine cycle. The fuel pressure pulsation is transmitted from the low pressure fuel path 42 to the low pressure fuel distribution pipes 18 and 22 through the low pressure fuel passage 54 and the branch passage 54a.

  Here, the ECU 56 executes the fuel injection mode control process shown in FIG. 2 based on the program stored in the internal memory. This process is a process that is repeatedly executed at regular time intervals. The steps in the flowchart corresponding to the individual processing contents are represented by “S˜”.

  When this process is started, the operating state data of the engine 2 is first read into a work area set in the memory of the ECU 56 (S102). Here, the load (fuel injection amount or accelerator opening) and the engine speed are read.

  Based on the relationship between the load and the engine speed, the fuel injection mode is set from the map shown in FIG. 3 (S104). This map is configured such that in-cylinder injection is set on the high load and high rotation side, and intake port injection is set on the low load and low rotation side.

  If it is determined in step S104 that the relationship between the load and the engine speed is the in-cylinder injection region, in-cylinder injection is set for all the cylinders 4 to 14 in the left and right banks 2a and 2b (S106). Thus, in the fuel injection control executed by the ECU 56, an amount of fuel required for engine operation is injected from the in-cylinder injection fuel injection valves 4a to 14a into the combustion chamber.

  If it is determined in step S104 that the relationship between the load and the engine speed is within the intake port injection region, it is then determined whether the intake port injection region is also within the intake port injection restriction region. (S108). This intake port injection restriction region corresponds to the “region where the variation in the fuel injection amount from the intake port injection fuel injection valve is large due to the fuel pressure pulsation generated by the high pressure pump”.

  Here, the intake port injection restriction region is a region indicated by a broken line in FIG. 3, and is particularly set in a low rotational speed region below the reference engine rotational speed NEx (corresponding to the reference rotational speed) and a low load region below the reference load Qx. ing.

  When the in-cylinder injection is stopped and only the intake port injection is performed, the low pressure fuel pressure pulsation due to the fuel intake and return of the high pressure fuel pump 26 described above increases. Particularly on the low engine speed side, such a low pressure fuel pressure pulsation resonates in the low pressure fuel pressure pulsation transmission path from the high pressure fuel pump 26 to the low pressure fuel distribution pipes 18 and 22, thereby generating a larger fuel pressure pulsation. The boundary of whether or not this fuel pressure pulsation causes a problem in the variation in the fuel injection amount by the intake port injection fuel injection valves 4b to 14b is determined in advance by experiment and set as the reference engine speed NEx.

  The reference load Qx itself is unrelated to the resonance of the fuel pressure pulsation, but the fuel injection period becomes longer on the high load side. Thus, if the fuel injection period is long, even if the fuel pressure pulsation itself is large, the variation in the fuel injection amount due to the fuel pressure pulsation is offset, and the variation in the fuel injection amount by the intake port injection fuel injection valves 4b to 14b is small. Become. A boundary on whether or not there is no problem in the variation due to the cancellation of the variation in the fuel injection amount is determined in advance by an experiment and set as the reference load Qx.

  Here, if it is determined that the relationship between the load and the engine speed is outside the intake port injection restriction region ("NO" in S108). Intake port injection is set for all the cylinders 4 to 14 in the left and right banks 2a and 2b (S110). Thus, in the fuel injection control executed by the ECU 56, an amount of fuel required for engine operation is injected from the intake port injection fuel injection valves 4b to 14b into the intake port.

  FIG. 4 shows an example in which the engine speed is greater than the reference engine speed NEx. In this case, the low pressure fuel pressure pulsation becomes small, and even if the intake port injection is executed, the variation in the fuel injection amount between the left bank 2a and the right bank 2b is small. Therefore, the air-fuel ratio controllability of the engine 2 is not adversely affected.

  FIG. 5 shows an example when the load is larger than the reference load Qx. In this case, although the low-pressure fuel pressure pulsation is large, the variation in the fuel injection amount is offset by the long fuel injection period. For this reason, even if the intake port injection is executed, the variation in the fuel injection amount between the left bank 2a and the right bank 2b is small. Therefore, the air-fuel ratio controllability is not adversely affected.

  On the other hand, if it is determined that the relationship between the load and the engine speed is within the intake port injection restriction region ("YES" in S108), # 1 cylinder 4, # 3 cylinder 8 and # 5 cylinder 12 in the left bank 2a. Is set to intake port injection (S112). In-cylinder injection is set for # 2 cylinder 6, # 4 cylinder 10 and # 6 cylinder 14 of right bank 2b (S114). Thus, in the fuel injection control executed by the ECU 56, the amount of fuel required for engine operation is taken from the intake port injection fuel injection valves 4b, 8b, 12b for the three cylinders 4, 8, 12 of the left bank 2a. Injected into the port. The three cylinders 6, 10, and 14 in the right bank 2b are injected from the in-cylinder injection fuel injection valves 6a, 10a, and 14a into the combustion chamber.

  FIG. 6 shows an example in which the relationship between the load and the engine speed is within the intake port injection restriction region. In this case, since the in-cylinder injection is executed for the right bank 2b, the fuel pressure pulsation itself generated by the high-pressure fuel pump 26 is small. Since only the left bank 2a is the intake port injection, the variation in the fuel injection amount between the left bank 2a and the right bank 2b is reduced. Furthermore, since the intake port injection timing is set to the same phase of the low pressure fuel pressure pulsation in the left bank 2a, there is no variation in the fuel injection amount between the cylinders 4, 8, and 12 in the left bank 2a. Therefore, the air-fuel ratio controllability is not adversely affected.

In the configuration described above, the relationship with the claims corresponds to the processing as the intake port injection limiting means in steps S108, S112, and S114 of the fuel injection mode control processing (FIG. 2).
According to the first embodiment described above, the following effects can be obtained.

  (I). In the intake port injection restriction region, the intake port injection mode is limited to the left bank 2a only, and the in-cylinder injection is executed for the right bank 2b. Therefore, as described with reference to FIG. 6, the variation in the fuel injection amount between the banks 2a and 2b becomes very small. Therefore, the air-fuel ratio controllability for each of the banks 2a and 2b is improved, and the air-fuel ratio controllability of the engine 2 as a whole is also improved.

Further, there is no variation in the fuel injection amount between the cylinders 4, 8, and 12 of the left bank 2a. For this reason, the air fuel ratio controllability improvement of the engine 2 becomes more effective.
(B). The intake port injection restriction region in the operation region in which the intake port injection mode is executed is set based on the reference engine speed NEx. As a result, it is possible to easily determine the region where the variation in the fuel injection amount in the intake port injection is large. As a result, the air-fuel ratio controllability of the engine 2 as a whole can be improved.

  (C). Regarding the determination of the intake port injection restriction region, a range in which the variation in the fuel injection amount from the intake port injection fuel injection valves 4b to 14b is substantially suppressed by the fuel injection period becoming longer at the reference load Qx. I try to remove it. As a result, the frequency of switching the fuel injection mode within the operation region in which the intake port injection mode is executed can be reduced, and a more stable engine operation can be achieved.

[Embodiment 2]
In the present embodiment, fuel injection is stopped for the right bank 2b in the intake port injection restriction region. FIG. 7 shows a fuel injection mode control process for realizing this control. In this process, as compared with the fuel injection mode control process (FIG. 2), the fuel injection to the cylinders 6, 10, and 14 of the right bank 2b is stopped, and the suction of these cylinders 6, 10, and 14 is stopped. The difference is that the exhaust valve stops when it is closed. That is, when it is within the intake port injection restriction region (“YES” in S208), intake port injection is performed for each cylinder 4, 8, 12 of the left bank 2a (S212), but each cylinder 6, 6 of the right bank 2b is performed. For 10 and 14, fuel injection is stopped without executing in-cylinder injection or intake port injection (S214). Therefore, combustion is not performed in the cylinders 6, 10, and 14 of the right bank 2b. Then, the drive is stopped when the intake valve and the exhaust valve are closed (S216). As a result, the intake air is not directly discharged from the right bank 2b to the exhaust system. The processes in steps S202 to S212 are the same as steps S102 to S112 in the fuel injection mode control process (FIG. 2).

  Since the hardware configuration is basically the same as that of the first embodiment shown in FIG. 1, the hardware configuration will be described with reference to FIG. However, in order to enable the processing of step S216, at least the intake valves and exhaust valves provided in the respective cylinders 6, 10, and 14 of the right bank 2b are configured as electromagnetically driven valves, or variable valve mechanisms are provided. It has been. As a result, when fuel injection is stopped for the right bank 2b within the intake port injection restriction region, the intake valves and exhaust valves provided in the cylinders 6, 10, and 14 of the right bank 2b stop driving and close. The valve state can be maintained.

  FIG. 8 shows an example in which the relationship between the load and the engine speed is within the intake port injection restriction region. In this case, since in-cylinder injection is not executed in any of the banks 2a and 2b, the low pressure fuel pressure pulsation is large, but only the left bank 2a is intake port injection, and the right bank 2b is shut down. Therefore, there is no variation in the fuel injection amount between the banks 2a and 2b. Further, in the left bank 2a, since the intake port injection timing is set to the same phase of the low pressure fuel pressure pulsation, there is no variation in the fuel injection amount between the cylinders 4, 8, and 12. Therefore, the air-fuel ratio controllability is not adversely affected.

In the above-described configuration, the relationship with the claims corresponds to steps S208 and S212 to S216 of the fuel injection mode control processing (FIG. 7) as processing as the intake port injection limiting means.
According to the second embodiment described above, the following effects can be obtained.

  (I). As shown in FIG. 8, in the intake port injection restriction region, the execution of the intake port injection mode is restricted to the left bank 2a, the fuel injection is completely stopped for the right bank 2b, and the intake and exhaust valves are closed. For this reason, the fuel pressure pulsation generated by the high-pressure fuel pump 26 is irrelevant for the right bank 2b, and there is no variation in the fuel injection amount between the banks 2a and 2b. Therefore, the air-fuel ratio controllability for each of the banks 2a and 2b is improved, and the air-fuel ratio controllability of the engine 2 as a whole is also improved.

Further, there is no variation in the fuel injection amount between the cylinders 4, 8, and 12 of the left bank 2a. For this reason, the air fuel ratio controllability improvement of the engine 2 becomes more effective.
(B). The effects (b) and (c) of the first embodiment are produced.

[Embodiment 3]
In this embodiment, in-cylinder injection is executed in both the left and right banks 2a and 2b in the intake port injection restriction region. FIG. 9 shows a fuel injection mode control process for realizing this control process. In this process, as compared with the fuel injection mode control process (FIG. 2), when it is within the intake port injection restriction region (“YES” in S308), all the cylinders 4 to 4 in the left and right banks 2a and 2b. 14 is different in that in-cylinder injection is executed (S312). Therefore, the intake port injection is not executed in either of the left and right banks 2a and 2b. The processes in steps S302 to S310 are the same as steps S102 to S110 in the fuel injection mode control process (FIG. 2). The hardware configuration is the same as that of the first embodiment shown in FIG.

  FIG. 10 shows an example in which the relationship between the load and the engine speed is within the intake port injection restriction region. In this case, since in-cylinder injection is executed in any of the banks 2a and 2b, the low pressure fuel pressure pulsation is small. Since no intake port injection is performed, there is no variation in the fuel injection amount between the banks 2a and 2b due to the low pressure fuel pressure pulsation. Therefore, the air-fuel ratio controllability is not adversely affected.

In the configuration described above, the relationship with the claims corresponds to the processing as the intake port injection limiting means in steps S308 and S312 of the fuel injection mode control processing (FIG. 9).
According to the third embodiment described above, the following effects can be obtained.

  (I). As shown in FIG. 10, in the intake port injection restriction region, fuel is injected by in-cylinder injection for all the cylinders 4 to 14 in the left and right banks 2a and 2b. For this reason, the fuel pressure pulsation generated by the high-pressure fuel pump 26 is irrelevant in the left and right banks 2a and 2b, and there is no variation in the fuel injection amount between the banks 2a and 2b. Therefore, the air-fuel ratio controllability of the engine 2 as a whole is improved.

(B). The effects (b) and (c) of the first embodiment are produced.
[Embodiment 4]
In the present embodiment, in the intake port injection restriction region, the left bank 2a performs in-cylinder injection, and the right bank 2b stops operation without fuel injection. A fuel injection mode control process for realizing this control process is shown in FIG. In this process, compared to the fuel injection mode control process (FIG. 7), when it is in the intake port injection restriction region (“YES” in S408), in-cylinder injection is executed for the left bank 2a ( S412) is different. Therefore, the intake port injection is not executed in either of the left and right banks 2a and 2b. The processes of steps S402 to S410, S414, and S416 are the same as steps S202 to S210, S214, and S216 of the fuel injection mode control process (FIG. 7). The hardware configuration is as described in the second embodiment.

  FIG. 12 shows an example in which the relationship between the load and the engine speed is within the intake port injection restriction region. In this case, since the in-cylinder injection is executed in the left bank 2a, the low pressure fuel pressure pulsation is relatively small, but the right bank 2b is not operating, so the fuel injection amount between the banks 2a and 2b. There is no variation. Therefore, the air-fuel ratio controllability is not adversely affected.

In the configuration described above, the relationship with the claims corresponds to the processing as the intake port injection limiting means in steps S408 and S412 to S416 of the fuel injection mode control processing (FIG. 11).
According to the fourth embodiment described above, the following effects can be obtained.

  (I). In the intake port injection restriction region, the intake port injection mode is not executed, and the left bank 2a performs in-cylinder injection. Then, the fuel injection is completely stopped for the right bank 2b, and the intake and exhaust valves are closed. Therefore, the low pressure fuel pressure pulsation generated by the high pressure fuel pump 26 is irrelevant in both the left and right banks 2a and 2b, and there is no variation in the fuel injection amount between the banks 2a and 2b. Therefore, the air-fuel ratio controllability of the engine 2 as a whole is improved.

(B). The effects (b) and (c) of the first embodiment are produced.
[Embodiment 5]
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 pump side that pumps 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 (FIG. 1), and is therefore denoted by the same reference numeral.

  FIG. 14 shows a fuel injection mode control process executed by the ECU 156 in such a configuration. The other processes executed by the ECU 156 are basically the same as the processes executed by the ECU 56.

  The fuel injection mode control process (FIG. 14) does not exist in the left and right banks, but is substantially the same as the fuel injection mode control process (FIG. 9) described in the third embodiment. Therefore, steps S502 to S512 in FIG. 14 are in-cylinder with respect to all the cylinders 104 to 114 as long as they are within the intake port injection restriction region (“YES” in S508) as described in steps S302 to S312 in FIG. Injection is performed (S512).

  FIG. 15 shows an example of the case where it is determined in step S504 that the intake port injection mode is set, but is not within the intake port injection restriction region (“NO” in S508). In this case, intake port injection is set for all the cylinders 104 to 114 (S510). At this time, since the low pressure fuel pressure pulsation (one cycle has a crank angle of 240 °) is small, the variation in the fuel injection amount between the cylinders 104 to 114 is small even when the fuel injection timing is at an interval of 120 ° of the crank angle. Therefore, the air-fuel ratio controllability is not adversely affected.

  FIG. 16 shows an example of the case where it is determined in step S504 that the intake port injection mode is set, and it is further determined that the intake port injection is within the restriction range (“YES” in S508). In this case, in-cylinder injection is set for all the cylinders 104 to 114 (S512). At this time, the low pressure fuel pressure pulsation does not affect the fuel injection amount, and there is no variation in the fuel injection amount between the cylinders 104 to 114. Therefore, the air-fuel ratio controllability is not adversely affected.

In the configuration described above, the relationship with the claims corresponds to the processing as the intake port injection limiting means in steps S508 and S512 of the fuel injection mode control processing (FIG. 14).
According to the fifth embodiment described above, the following effects can be obtained.

  (I). Within the intake port injection restriction region, fuel injection from the intake port injection fuel injection valves 104b to 114b is stopped and fuel injection from the in-cylinder injection fuel injection valves 104a to 114a is stopped even in the intake port injection mode. Running. Accordingly, the fuel pressure pulsation of the low-pressure fuel does not affect the fuel injection amount, so that the problem of variation in the fuel injection amount among the cylinders 104 to 114 is solved.

For this reason, the air-fuel ratio controllability for each of the cylinders 104 to 114 is improved, and the air-fuel ratio controllability of the engine 102 as a whole is also improved.
(B). For the reason described in the first embodiment (b), the air-fuel ratio controllability of each of the cylinders 104 to 114 can be improved, and the air-fuel ratio controllability of the engine 102 as a whole can be improved.

(C). The effect (c) of the first embodiment is produced.
[Other embodiments]
(A). As indicated by the broken line in FIG. 3, the intake port injection restriction region was set to a region below the reference engine speed NEx and the reference load Qx, but the low pressure fuel pressure pulsation due to resonance is related to the engine speed. A region below the reference engine speed NEx may be used as the intake port injection restriction region regardless of the load.

  (B). In the first embodiment, when in the intake port injection restriction region, the left bank 2a may be in-cylinder injection and the right bank 2b may be intake port injection. Further, in the second embodiment, when it is within the intake port injection restriction region, the left bank 2a may stop the injection and the right bank 2b may be the intake port injection. Further, in the fourth embodiment, when it is within the intake port injection restriction region, the left bank 2a may stop the injection, and the right bank 2b may be in-cylinder injection.

  (C). In the first to fourth embodiments, an example of a two-bank engine has been described. However, the present invention may be applied to an engine having three or more banks. In this case, when it is within the intake port injection restriction region, the number of banks for performing the intake port injection is limited to one, or the bank for performing the intake port injection is not provided. As a result, the low-pressure fuel pressure pulsation generated by the high-pressure fuel pump does not cause variations in the fuel injection amount among the banks, so that the air-fuel ratio controllability is improved even in engines with three or more banks.

(D). 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.
(E). In each of the above-described embodiments, the description has been given with respect to the six-cylinder engine. However, the present invention can be applied to a multi-cylinder engine having less than six cylinders and an engine having more than six cylinders.

1 is a schematic configuration diagram of an engine and a fuel supply system as a first embodiment. 4 is a flowchart of fuel injection mode control processing executed by the ECU according to the first embodiment. The structure explanatory view of the fuel injection mode setting map in the above-mentioned fuel injection mode control processing. 3 is a graph showing an example of a fuel injection process in an intake port injection mode according to the first embodiment. 3 is a graph showing an example of a fuel injection process in an intake port injection mode according to the first embodiment. 6 is a graph showing an example of a fuel injection process when the intake port injection restriction region is within an intake port injection restriction region in the first embodiment. 7 is a flowchart of fuel injection mode control processing executed by the ECU according to the second embodiment. 7 is a graph showing an example of a fuel injection process when the intake port injection restriction region is within an intake port injection restriction region in the second embodiment. 10 is a flowchart of fuel injection mode control processing executed by the ECU according to the third embodiment. FIG. 10 is a graph showing an example of fuel injection processing when the intake port injection restriction region is entered in the intake port injection mode of Embodiment 3. FIG. 10 is a flowchart of fuel injection mode control processing executed by the ECU according to the fourth embodiment. FIG. 9 is a graph showing an example of fuel injection processing when the intake port injection restriction region is reached in the intake port injection mode of the fourth embodiment. FIG. 6 is a schematic configuration diagram of an engine and a fuel supply system as a fifth embodiment. 10 is a flowchart of fuel injection mode control processing executed by the ECU according to the fifth embodiment. 10 is a graph showing an example of a fuel injection process in an intake port injection mode according to the fifth embodiment. FIG. 16 is a graph showing an example of fuel injection processing when the intake port injection mode is in an intake port injection restriction region according to the fifth embodiment.

Explanation of symbols

  2 ... Engine, 2a ... Left bank, 2b ... Right bank, 4, 6, 8, 10, 12, 14 ... Cylinder, 4a, 6a, 8a, 10a, 12a, 14a ... Fuel injection valve for in-cylinder injection, 4b, 6b, 8b, 10b, 12b, 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 ... 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.

Claims (7)

An intake port injection fuel injection valve that injects fuel into the intake port of each cylinder of the internal combustion engine, an in-cylinder injection fuel injection valve that directly injects fuel into the combustion chamber of each cylinder, and a low pressure pressurized by a low pressure pump A fuel supply system that supplies fuel to the intake port injection fuel injection valve and pressurizes the low pressure fuel by a high pressure pump as high pressure fuel to the in-cylinder injection fuel injection valve; A fuel injection device for an internal combustion engine that executes an intake port injection mode in which fuel is injected only from the fuel injection valve for intake port injection according to
In the intake port injection mode, in the region where the variation in the fuel injection amount from the intake port injection fuel injection valve is large due to the fuel pressure pulsation generated by the high pressure pump in the operating state of the internal combustion engine, A fuel injection device for an internal combustion engine, comprising: an intake port injection limiting means for stopping fuel injection from the fuel injection valve for intake port injection and executing fuel injection from the fuel injection valve for in-cylinder injection . 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 A fuel distribution pipe, an in-cylinder injection fuel injection valve that directly injects fuel into the combustion chamber of each cylinder, 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 supplied to the high-pressure pump A fuel supply system that pressurizes the fuel and supplies the fuel as a high-pressure fuel to the in-cylinder fuel injection valve, and injects fuel only from the intake port fuel injection valve in accordance with the operating state of the internal combustion engine. A fuel injection device for an internal combustion engine that executes a mode,
In the region where the variation of the fuel injection amount from the fuel injection valve for intake port injection is large due to the fuel pressure pulsation generated by the high-pressure pump in the operating state of the internal combustion engine, the intake port in all banks A fuel injection device for an internal combustion engine, comprising an intake port injection restriction means for restricting the number of banks for executing the injection mode to one or less. 3. The internal combustion engine according to claim 2, wherein the intake port injection limiting means executes fuel injection from the in-cylinder fuel injection valve for banks other than the bank that executes the intake port injection mode. Fuel injectors. 3. The intake port injection limiting device according to claim 2, wherein when the intake port injection mode is executed in one bank, the fuel injection from the in-cylinder injection fuel injection valve is executed for the other bank. Alternatively, a fuel injection device for an internal combustion engine, wherein the fuel injection is stopped. 3. The fuel injection from the in-cylinder injection fuel injection valve in one or more banks according to claim 2, wherein the intake port injection limiting means does not execute the intake port injection mode in any bank. And the fuel injection for the other banks is stopped. 6. The fuel injection device for an internal combustion engine according to claim 2, wherein the internal combustion engine includes two banks. 7. The intake port injection mode according to claim 1, wherein the intake port injection mode is executed in an operating region provided on a low load side of the internal combustion engine, and in a rotational speed region lower than a reference rotational speed provided in the operating region. A fuel injection device for an internal combustion engine, wherein a region in which a variation in fuel injection amount from the fuel injection valve for intake port injection is large is set.

Images