JP2021076089A - Internal combustion engine fuel supply device - Google Patents

Abstract

To provide an internal combustion engine fuel supply device capable of appropriately adjusting a fuel amount supplied to a cylinder during a single cycle of an internal combustion engine even when the same is in high load operation.SOLUTION: A control unit 60 of a fuel supply device 30 performs: estimation processing to estimate whether or not a required fuel supply amount is equal to or larger than a rated amount when an internal combustion engine 10 is put into high load operation; low pressure increase processing to control a low pressure fuel pump 36 so that fuel pressure inside respective low pressure delivery pipes 33A and 33B is increased when the required fuel supply amount is estimated to be equal to or larger than the rated amount through the estimation processing; and injection processing to allow both an in-cylinder injection valve 32 and a port injection valve 31 to inject fuel when the internal combustion engine 10 is in the high load operation and the required fuel supply amount is equal to or larger than the rated amount.SELECTED DRAWING: Figure 1

Description

The present invention relates to an internal combustion engine fuel supply device applied to an internal combustion engine having a plurality of banks.

Patent Document 1 discloses a V-type internal combustion engine as an example of an internal combustion engine having a plurality of banks. In the internal combustion engine, both a port injection valve that injects fuel into the intake port and an in-cylinder injection valve that injects fuel into the cylinder are provided for each cylinder.

In the fuel supply device applied to the V-type internal combustion engine, both a high-pressure delivery pipe to which the in-cylinder injection valve is connected and a low-pressure delivery pipe to which the port injection valve is connected are provided for each bank. Further, the fuel supply device includes a low-pressure fuel pump that pumps fuel from the fuel tank and discharges the fuel, and a high-pressure fuel pump that pressurizes and discharges the fuel discharged from the low-pressure fuel pump. Then, the low-pressure fuel discharged from the low-pressure fuel pump is stored in each low-pressure delivery pipe. Further, a part of the low-pressure fuel discharged from the low-pressure fuel pump is pressurized by the high-pressure fuel pump and supplied into each high-pressure delivery pipe.

Although the fuel supply device disclosed in Patent Document 1 includes two high-pressure delivery pipes, it includes only one high-pressure fuel pump.

Japanese Unexamined Patent Publication No. 2013-122198

In an internal combustion engine having both a port injection valve and an in-cylinder injection valve, the fuel injection of the port injection valve and the fuel injection of the in-cylinder injection valve are controlled based on the operating point of the internal combustion engine. For example, when the internal combustion engine is operated with a high load, the fuel injection of the in-cylinder injection valve is performed, while the fuel injection of the port injection valve is stopped.

In a fuel supply device equipped with only one high-pressure fuel pump despite having two high-pressure delivery pipes as described above, when a high-load operation is performed in the internal combustion engine equipped with the fuel supply device, the port injection valve Consider the case where fuel injection is stopped. In this case, the in-cylinder injection valve is controlled so that the required fuel supply amount, which is the required value of the fuel supply amount into the cylinder in one cycle of the internal combustion engine, and the fuel injection amount of the in-cylinder injection valve become equal to each other. Will be. However, if the required fuel supply amount is large, the number of high-pressure fuel pumps is only one, so that the fuel is supplied from the high-pressure fuel pump to each high-pressure delivery pipe with respect to the fuel injection amount of each in-cylinder injection valve. May not catch up and the fuel pressure in each high-pressure delivery pipe may fall below the target value. In such a case, it is necessary to lengthen the fuel injection time of the in-cylinder injection valve, but there is a possibility that the fuel injection of the in-cylinder injection valve cannot be completed by the ignition timing in the cylinder. That is, there is a possibility that a discrepancy may occur between the actual amount of fuel supplied into the cylinder and the required fuel supply amount by the ignition timing in the cylinder.

The fuel supply device for an internal combustion engine for solving the above problems is applied to an internal combustion engine having a plurality of banks. This fuel supply device is provided for each cylinder of the internal combustion engine, has a plurality of port injection valves for injecting fuel into the intake port of the internal combustion engine, and is provided for each cylinder and injects fuel into the cylinder. A plurality of in-cylinder injection valves, a first low-pressure delivery pipe to which some of the port injection valves of the port injection valves are connected, and the remaining port injection valves of the port injection valves. The second low-pressure delivery pipe to be connected, the first high-pressure delivery pipe to which some of the in-cylinder injection valves of the in-cylinder injection valves are connected, and the remaining of the in-cylinder injection valves. A second high-pressure delivery pipe to which an in-cylinder injection valve is connected, a low-pressure fuel pump that pumps fuel from a fuel tank and discharges it, a high-pressure fuel pump that pressurizes and discharges fuel discharged from the low-pressure fuel pump, and the above. A control device for controlling the fuel injection of each port injection valve and the fuel injection of each in-cylinder injection valve based on the operating point of the internal combustion engine is provided. The fuel discharged from the low-pressure fuel pump is stored in each of the low-pressure delivery pipes, and the fuel discharged from the high-pressure fuel pump is stored in each of the high-pressure delivery pipes. When the required value of the fuel supply amount into the cylinder in one cycle of the internal combustion engine is set as the fuel supply amount required value, the control device performs the fuel supply amount required value with the high load operation of the internal combustion engine. However, when the estimation process for estimating whether or not the fuel discharge capacity of the high-pressure fuel pump exceeds the specified amount, and the estimation process estimates that the required fuel supply amount exceeds the specified amount, The low-pressure increasing process for controlling the low-pressure fuel pump so that the fuel pressure in each low-pressure delivery pipe is higher than when the required fuel supply amount is not estimated to be equal to or higher than the specified amount, and the internal combustion engine When performing high-load operation, when the required fuel supply amount is less than the specified amount, the in-cylinder injection valve is made to inject fuel, while the fuel injection of the port injection valve is stopped to request the fuel supply amount. When the value is equal to or more than the specified amount, the injection process of injecting fuel from both the in-cylinder injection valve and the port injection valve is executed.

According to the above configuration, when it is estimated by the estimation process that the required fuel supply amount exceeds the specified amount due to the high load operation of the internal combustion engine, the low pressure increase process is performed, so that the pressure in each low pressure delivery pipe is increased. Fuel pressure is increased. When the port injection valve is made to inject fuel under the condition that the fuel pressure in each low-pressure delivery pipe is increased in this way, the fuel injection amount of the port injection valve can be increased without lengthening the fuel injection time. ..

When the internal combustion engine performs high-load operation after increasing the fuel pressure in each low-pressure delivery pipe in this way, when the required fuel supply amount is equal to or more than the specified amount, the in-cylinder injection valve and the port injection valve Fuel is injected from both sides. In this case, the fuel injection amount of the in-cylinder injection valve can be reduced as compared with the case where the fuel injection of the port injection valve is not performed, so that the fuel injection of the in-cylinder injection valve is not completed even at the ignition timing. The occurrence of events can be suppressed. In addition, since the fuel pressure in the low-pressure delivery pipe is high, even if the engine speed is high and the intake valve is open for a short time, the fuel injection of the port injection valve is performed before the intake valve closes. Can be completed. As a result, it is possible to prevent a discrepancy between the amount of fuel actually supplied into the cylinder and the required value of the fuel supply amount due to the fuel injection of both the port injection valve and the in-cylinder injection valve.

Therefore, according to the above configuration, the amount of fuel supplied into the cylinder can be appropriately adjusted in one cycle of the internal combustion engine even when the internal combustion engine operates with a high load.

The schematic block diagram which shows the fuel supply apparatus of embodiment and the internal combustion engine to which the fuel supply apparatus is applied. The block diagram explaining a part of the processing performed by the control device of the fuel supply device. A map for determining the injection valve that injects fuel based on the operating point of the internal combustion engine, which is determined by the engine load factor and the engine rotation speed. A block diagram illustrating a part of the processing executed by the control device. A block diagram illustrating a part of the processing executed by the control device. The flowchart explaining the content of the low pressure fuel pressure target value derivation process shown in FIG. Operation diagram showing the transition of the low pressure fuel pressure target value.

Hereinafter, an embodiment of a fuel supply device for an internal combustion engine will be described with reference to FIGS. 1 to 7.
FIG. 1 illustrates the fuel supply device 30 of the present embodiment and the V-type internal combustion engine 10 to which the fuel supply device 30 is applied. The internal combustion engine 10 has two banks. A plurality of cylinders 11 are provided in each bank. A piston 12 is housed in each cylinder 11 in a state where it can reciprocate. Then, when the intake valve 14 is open, intake air is introduced into the combustion chamber 13 in each cylinder 11 through the intake passage 15. The intake passage 15 is provided with a throttle valve 16 that operates to adjust the amount of intake air introduced into the combustion chamber 13. The portion of the intake passage 15 connected to the combustion chamber 13 is referred to as an intake port 151.

The fuel supply device 30 includes the same number of port injection valves 31 and in-cylinder injection valves 32 as the number of cylinders of the internal combustion engine 10. Each port injection valve 31 injects fuel into the intake port 151 that communicates with the corresponding cylinder 11. Each in-cylinder injection valve 32 injects fuel directly into the combustion chamber 13 in the corresponding cylinder 11. In the combustion chamber 13, the spark discharge of the spark plug burns the air-fuel mixture containing the fuel injected from the injection valves 31 and 32 and the intake air introduced into the combustion chamber 13 via the intake port 151. Then, the exhaust gas generated in the combustion chamber 13 by the combustion of the air-fuel mixture is discharged to the exhaust passage 18 when the exhaust valve 17 is open.

The fuel supply device 30 includes the same number of low-pressure delivery pipes 33A and 33B and high-pressure delivery pipes 34A and 34B as the number of banks of the internal combustion engine 10. Of the low-pressure delivery pipes 33A and 33B, the first low-pressure delivery pipe 33A is connected to each port injection valve 31 for one of the two banks. Further, each port injection valve 31 for the other bank of the two banks is connected to the second low-pressure delivery pipe 33B. Of the high-pressure delivery pipes 34A and 34B, the in-cylinder injection valve 32 for one of the two banks is connected to the first high-pressure delivery pipe 34A. Further, each in-cylinder injection valve 32 for the other bank of the two banks is connected to the second high-pressure delivery pipe 34B.

The fuel supply device 30 includes an electric low-pressure fuel pump 36 that pumps fuel from the fuel tank 300 and discharges the fuel, and a low-pressure fuel passage 37 through which the fuel discharged from the low-pressure fuel pump 36 flows. The low-pressure delivery pipes 33A and 33B are connected to the low-pressure fuel passage 37. Therefore, the low-pressure fuel discharged from the low-pressure fuel pump 36 is temporarily stored in the low-pressure delivery pipes 33A and 33B.

The fuel supply device 30 includes a high-pressure fuel pump 38 that further pressurizes the fuel in the low-pressure fuel passage 37. The high-pressure fuel discharged from the high-pressure fuel pump 38 is supplied to the first high-pressure delivery pipe 34A of the high-pressure delivery pipes 34A and 34B. Further, the insides of the high-pressure delivery pipes 34A and 34B communicate with each other via the connecting passage 39. Therefore, the high-pressure fuel discharged from the high-pressure fuel pump 38 is temporarily stored in the high-pressure delivery pipes 34A and 34B. That is, in the present embodiment, the number of high-pressure fuel pumps 38 is one even though a plurality of high-pressure delivery pipes 34A and 34B are provided.

The high-pressure fuel pump 38 includes a suction passage 41 connected to the low-pressure fuel passage 37, a discharge passage 42 connected to the first high-pressure delivery pipe 34A, and a pressurizing portion 45. The pressurizing unit 45 has a pressurizing chamber 48 communicating with the suction passage 41 and the discharge passage 42. A check valve that allows the flow of fuel from the pressurizing chamber 48 to the first high-pressure delivery pipe 34A in the discharge passage 42, while restricting the flow of fuel from the first high-pressure delivery pipe 34A to the pressurizing chamber 48. 43 is provided. Further, the high-pressure fuel pump 38 allows fuel to flow between the low-pressure fuel passage 37 and the pressurizing chamber 48 through the suction passage 41 when the valve is open, while the suction passage is closed when the valve is closed. An electric suction valve 44 that regulates the flow of fuel between the low-pressure fuel passage 37 and the pressurizing chamber 48 through the 41 is provided.

The pressurizing unit 45 pressurizes the fuel that has flowed into the pressurizing chamber 48 and discharges it into the discharge passage 42. Specifically, the pressurizing unit 45 has a cylinder 46 and a plunger 47 that reciprocates in the cylinder 46. The pressurizing chamber 48 is partitioned by the cylinder 46 and the plunger 47. The plunger 47 reciprocates in conjunction with the rotation of the cam piece 191 that rotates integrally with the cam shaft 19 of the internal combustion engine 10. The volume of the pressurizing chamber 48 changes as the plunger 47 reciprocates. The camshaft 19 rotates synchronously with the crankshaft of the internal combustion engine 10.

When the plunger 47 moves in the direction of increasing the volume of the pressurizing chamber 48 while the suction valve 44 is open, fuel is supplied to the pressurizing chamber 48 via the suction passage 41. Then, when the plunger 47 moves in the direction of reducing the volume of the pressurizing chamber 48 while the suction valve 44 is closed, the fuel pressure in the pressurizing chamber 48 increases. When the check valve 43 is opened due to the increase in the fuel pressure in the pressurizing chamber 48, the fuel in the pressurizing chamber 48 is supplied into the first high-pressure delivery pipe 34A via the discharge passage 42. The first high-pressure delivery pipe 34A is passed through the discharge passage 42 by changing the length of the period during which the suction valve 44 is closed when the plunger 47 is moving in the direction of reducing the volume of the pressurizing chamber 48. The amount of fuel supplied inside can be increased or decreased. That is, by interlocking the reciprocating motion of the plunger 47 and the opening / closing operation of the suction valve 44, fuel is sucked into the pressurizing chamber 48 from the low pressure fuel passage 37, and the fuel is pressurized to the high pressure delivery pipes 34A and 34B. Can be supplied.

Next, the control device 60 of the fuel supply device 30 will be described with reference to FIG.
Detection signals are input to the control device 60 from various sensors. Examples of the sensor include a low-pressure fuel pressure sensor 111, a high-pressure fuel pressure sensor 112, an air flow meter 113, a crank angle sensor 114, an air-fuel ratio sensor 115, and the like. The low-pressure fuel pressure sensor 111 detects the low-pressure fuel pressure PFL, which is the pressure of the fuel in the first low-pressure delivery pipe 33A, and outputs a signal corresponding to the detection result as a detection signal. The high-pressure fuel pressure sensor 112 detects the high-pressure fuel pressure PFH, which is the pressure of the fuel in the first high-pressure delivery pipe 34A, and outputs a signal corresponding to the detection result as a detection signal. The air flow meter 113 detects the intake air amount GA and outputs a signal corresponding to the detection result as a detection signal. The crank angle sensor 114 outputs a signal corresponding to the engine rotation speed NE, which is the rotation speed of the crankshaft of the internal combustion engine 10, as a detection signal. The air-fuel ratio sensor 115 detects the air-fuel ratio AF of the air-fuel mixture that burns in the cylinder 11, and outputs a signal corresponding to the detection result as a detection signal.

The control device 60 includes a central processing unit 61, a memory 62, and the like. The control device 60 executes various controls of the internal combustion engine 10 by the central processing unit 61 executing the program stored in the memory 62. In the following description, the central processing unit 61 is referred to as "CPU 61".

With reference to FIGS. 2 and 3, various processes executed by the CPU 61 when operating the injection valves 31 and 32 will be described.
As shown in FIG. 2, the fuel supply amount required value derivation process M11 is a process for deriving the fuel supply amount required value QF, which is the required value of the fuel supply amount into the cylinder 11 in one cycle of the internal combustion engine 10. .. In the fuel supply amount required value derivation process M11, the reference fuel supply amount is derived based on the engine speed NE and the engine load factor KL. The engine load factor KL can be calculated based on, for example, the engine rotation speed NE and the intake air amount GA. Then, the higher the engine speed NE, the larger the value is derived as the reference fuel supply amount. The higher the engine load factor KL, the larger the value is derived as the reference fuel supply amount. Further, in the fuel supply amount required value derivation process M11, the supply amount correction value is derived by feedback control in which the deviation between the air-fuel ratio target value AFTr, which is the target of the air-fuel ratio AF, and the air-fuel ratio AF is input. Then, in the fuel supply amount required value derivation process M11, the fuel supply amount required value QF is derived based on the reference supply amount and the supply amount correction value.

The injection process M110 determines an injection valve for injecting fuel based on the operating point of the internal combustion engine 10 determined by the engine load factor KL and the engine rotation speed NE, and causes the injection valve to inject fuel. For example, in the injection process M110, when the internal combustion engine 10 performs high load operation, when the required fuel supply amount QF is less than the specified amount described later, the in-cylinder injection valve 32 is made to inject fuel while the port injection valve 31. Stop fuel injection. On the other hand, when the required fuel supply amount QF is equal to or higher than the specified amount, fuel is injected from both the in-cylinder injection valve 32 and the port injection valve 31.

The injection process M110 includes an injection rate setting process M12, an injection amount target value derivation process M13, a port side operation process M14, and a cylinder inner operation process M15.
The injection division rate setting process M12 is a process for setting the target injection separation rate DITr based on the operating point of the internal combustion engine 10. That is, in the injection rate setting process M12, the operating point of the internal combustion engine 10 is obtained based on the engine load factor KL and the engine rotation speed NE, and the target injection rate DITr is set based on the operating point. The injection rate is the ratio of the fuel injection amount of the in-cylinder injection valve 32 to the fuel supply amount into the cylinder 11 in one cycle of the internal combustion engine 10. The target of the spouting rate is the target spouting rate DITr. The target ejection rate DITr is set to a value of "0" or more and "1" or less.

With reference to FIG. 3, the relationship between the operating point of the internal combustion engine 10 and the injection valve for injecting fuel will be described. FIG. 3 is an example of a map for determining an injection valve for fuel injection based on the operating point.

As shown in FIG. 3, the operating region of the internal combustion engine 10 has a relatively low engine load factor KL and a low engine speed region R1 in which the engine rotation speed NE has a low rotation speed NE, and the engine load factor KL. It can be divided into a high load region R3 in which the engine speed is high and the engine speed NE is high, and a medium load region R2 between the low load region R1 and the high load region R3.

When the operating point is in the low load region R1, "0%" is set as the target ejection rate DITr. In this case, the fuel injection of the in-cylinder injection valve 32 is stopped, while the fuel injection of the port injection valve 31 is performed. When the operating point is in the medium load region R2, a value higher than "0%" and lower than "100%" is set as the target ejection rate DITr. In this case, both the fuel injection of the in-cylinder injection valve 32 and the fuel injection of the port injection valve 31 are performed.

When the operating point is in the high load region R3, a value higher than "0%" is set as the target ejection rate DITr. When the operating point is in the high load region R3, the higher the engine speed NE, the larger the fuel supply amount required value QF, and the higher the engine load factor KL, the larger the fuel supply amount required value QF. Since the fuel supply device 30 of the present embodiment includes only one high-pressure fuel pump 38, if the fuel injection amount of the in-cylinder injection valve 32 in one cycle of the internal combustion engine 10 is large, each high-pressure delivery pipe 34A, The high-pressure fuel pressure PFH in 34B may not be maintained at the target value. In such a case, assuming that "100%" is set as the target injection rate DITr, the fuel injection of the in-cylinder injection valve 32 is performed before the start of combustion in the cylinder 11, that is, before the start of spark discharge of the spark plug. May not be able to be terminated.

Therefore, in the present embodiment, when the operating point of the internal combustion engine 10 is in the high load region R3, that is, when the internal combustion engine 10 performs high load operation, the target injection rate DITr is set in consideration of the fuel supply amount required value QF. Set. That is, when the fuel supply amount required value QF is not so large, the target injection rate DITr is set to "100%", while when the fuel supply amount required value QF is large, the target injection rate DITr is set to be higher than "0%". A value that is high and less than "100%" is set. Specifically, when the required fuel supply amount QF is less than the specified amount QFA, "100%" is set as the target injection rate DITr. On the other hand, when the required fuel supply amount QF is equal to or greater than the specified amount QFA, a value higher than "0%" and less than "100%" is set as the target injection rate DITr.

The specified amount QFA is a determination value set as a criterion for determining whether or not the fuel supply amount required value QF is large, and is determined from the fuel discharge capacity of the high-pressure fuel pump 38. However, the amount of fuel that can be discharged from the high-pressure fuel pump 38 depends on the engine speed NE. Therefore, the specified amount QFA may be set to a larger value as the engine rotation speed NE is higher.

As shown in FIG. 2, the injection amount target value derivation process M13 has a port injection amount target value QFP which is a target of the fuel injection amount of the port injection valve 31 and a cylinder which is a target of the fuel injection amount of the in-cylinder injection valve 32. This is a process for deriving the internal injection amount target value QFD. In the injection amount target value derivation process M13, the product of the fuel supply amount required value QF and the target injection rate DITr is derived as the in-cylinder injection amount target value QFD. Further, the amount obtained by subtracting the in-cylinder injection amount target value QFD from the fuel supply amount required value QF is derived as the port injection amount target value QFP.

The port-side operation process M14 is a process of outputting an operation signal MS1 corresponding to the low-pressure fuel pressure PFL and the port injection amount target value QFP to the port injection valve 31. In the port-side operation process M14, the operation signal MS1 that shortens the fuel injection period of the port injection valve 31 is output as the low-pressure fuel pressure PFL increases. Further, the smaller the port injection amount target value QFP, the shorter the fuel injection period of the port injection valve 31, the operation signal MS1 is output.

The in-cylinder operation process M15 is a process of outputting an operation signal MS2 corresponding to the high-pressure fuel pressure PFH and the in-cylinder injection amount target value QFD to the in-cylinder injection valve 32. In the in-cylinder operation process M15, the operation signal MS2 that shortens the fuel injection period of the in-cylinder injection valve 32 as the high-pressure fuel pressure PFH increases is output. Further, the operation signal MS2 that shortens the fuel injection period of the in-cylinder injection valve 32 is output as the in-cylinder injection amount target value QFD becomes smaller.

With reference to FIG. 4, various processes executed by the CPU 61 when operating the high-pressure fuel pump 38 will be described.
The valve opening time derivation process M21 is a process for deriving the valve opening time TMB of the suction valve 44 of the high-pressure fuel pump 38. In the valve opening time derivation process M21, the valve opening time TMB is set by feedback control in which the deviation between the high pressure fuel pressure target value PFHTr, which is the target of the high pressure fuel pressure PFH, and the high pressure fuel pressure PFH is input.

The intake valve operation process M22 is a process of outputting an operation signal MS3 according to the valve opening time TMB to the intake valve 44. In the intake valve operation process M22, an operation signal MS3 that makes the duration of valve opening of the intake valve 44 equal to the valve opening time TMB is output.

With reference to FIG. 5, various processes executed by the CPU 61 when operating the low-pressure fuel pump 36 will be described.
The estimation process M31 is a process for estimating whether or not the fuel supply amount required value QF becomes equal to or more than the above-mentioned specified amount QFA due to the high load operation of the internal combustion engine 10. When adjusting the throttle opening SL, which is the opening of the throttle valve 16, the throttle valve 16 is controlled based on the throttle opening target value SLTr according to the accelerator opening. However, in reality, there is a response delay in the operation of the throttle valve 16. Therefore, the throttle opening SL is adjusted in consideration of the response delay of the operation of the throttle valve 16. The response delay of the operation of the throttle valve 16 can be grasped in advance from the specifications of the power source of the throttle valve 16. Therefore, based on such information, it is possible to predict how the throttle opening SL and the intake air amount GA will change. In the estimation process M31, based on the result of such prediction, it is estimated whether or not the fuel supply amount required value QF is equal to or more than the specified amount QFA.

In the low-pressure increase processing M310, when the fuel supply amount required value QF is estimated to be equal to or higher than the specified amount QFA by the estimation processing M31, the fuel supply amount required value QF is higher than when it is not estimated to be equal to or higher than the specified amount QFA. This is a process of controlling the low-pressure fuel pump 36 so that the low-pressure fuel pressure PFL in the low-pressure delivery pipes 33A and 33B becomes high. Such a low pressure increasing process M310 includes a low pressure fuel pressure target value derivation process M32, a first arbitration process M33, a second arbitration process M34, and a pump operation process M35.

The low-pressure fuel pressure target value derivation process M32 is a process for deriving the target low-pressure fuel pressure basic value PFLTrB, which is the target basic value of the low-pressure fuel pressure PFL, based on the estimation result of the estimation process M31. The contents of the low-pressure fuel pressure target value derivation process M32 will be described later.

The first arbitration process M33 is a process for arbitrating the low pressure fuel pressure target value PFTra based on the functional requirement and the request of the low pressure fuel pressure target value derivation process M32. Examples of the functional requirements include a requirement for pre-driving the low-pressure fuel pump 36 at the time of starting the engine and a requirement for suppressing fuel vapor. When the low-pressure fuel pump 36 is pre-driven when the engine is started, a high pressure is set as the low-pressure fuel pressure target value PFTra. Further, in the fuel vapor suppression control, a high pressure is set as the low pressure fuel pressure target value PFTra in order to raise the low pressure fuel pressure in each of the low pressure delivery pipes 33A and 33B to raise the boiling point of the fuel. Therefore, in the first arbitration process M33, the higher of the required value of the low-pressure fuel pressure PFL from the functional requirement and the target low-pressure fuel pressure basic value PFLTrB derived in the low-pressure fuel pressure target value derivation process M32 is the low-pressure fuel pressure. It is derived as the target value PFTra.

The second arbitration process M34 is a process for deriving the low pressure fuel pressure target value PFTr based on the priority request and the low pressure fuel pressure target value PFTr derived in the first arbitration process M33. As a priority request, for example, a request for diagnosing whether or not the low-pressure fuel pump 36 and the low-pressure fuel pressure sensor 111 operate normally can be mentioned. In the second arbitration process M34, when there is such a priority request, the required value of the low pressure fuel pressure PFL required by the priority request is derived as the low pressure fuel pressure target value PFTr. On the other hand, in the absence of such a priority requirement, the low pressure fuel pressure target value PFTr is derived as the low pressure fuel pressure target value PFTr.

The pump operation process M35 is a process of outputting the operation signal MS4 to the low pressure fuel pump 36 to drive the low pressure fuel pump 36. That is, in the pump operation process M35, the control amount of the low pressure fuel pump 36 is derived by feedback control in which the deviation between the low pressure fuel pressure target value PFTr and the low pressure fuel pressure PFL is input. Then, the operation signal MS4 based on the control amount is output.

Next, with reference to FIG. 6, the low-pressure fuel pressure target value derivation process M32 executed by the CPU 61 will be described. The low-pressure fuel pressure target value derivation process M32 is repeatedly executed every predetermined control cycle.

In the low-pressure fuel pressure target value derivation process M32, if the CPU 61 does not estimate in the estimation process M31 that the required fuel supply amount QF is equal to or greater than the above-mentioned specified amount QFA (S11: NO), the process is performed in the next step S12. Transition. In the next step S12, the CPU 61 sets the first basic value PFL1 as the low pressure fuel pressure basic value PFLB. Then, the CPU 61 shifts the process to step S14.

On the other hand, when the CPU 61 estimates in the estimation process M31 that the fuel supply amount required value QF is equal to or greater than the specified amount QFA (S11: YES), the process proceeds to the next step S13. In step S13, the CPU 61 sets the second basic value PFL2 as the low pressure fuel pressure basic value PFLB. The second basal value PFL2 is higher than the first basal value PFL1. Then, the CPU 61 shifts the process to step S14.

In step S14, the CPU 61 determines whether or not the low pressure fuel pressure target value PFTr is less than the low pressure fuel pressure basic value PFLB. When the low-pressure fuel pressure target value PFTr is less than the low-pressure fuel pressure basic value PFLB (S14: YES), the CPU 61 shifts the process to the next step S15. In step S15, the CPU 61 derives the sum of the low-pressure fuel pressure basic value PFLB and the change amount α as the target low-pressure fuel pressure basic value PFLTrB. The change amount α is a preset value, which will be described in detail later. When the target low-pressure fuel pressure basic value PFLTrB is derived in this way, the CPU 61 temporarily terminates the low-pressure fuel pressure target value derivation process M32.

On the other hand, in step S14, when the low-pressure fuel pressure target value PFTr is equal to or higher than the low-pressure fuel pressure basic value PFLB (NO), the CPU 61 shifts the process to the next step S16. In step S16, the CPU 61 determines whether or not the low-pressure fuel pressure target value PFTr is higher than the low-pressure fuel pressure base value PFLB. When the low-pressure fuel pressure target value PFTr is higher than the low-pressure fuel pressure base value PFLB (S16: YES), the CPU 61 shifts the process to the next step S17. In step S17, the CPU 61 derives a value obtained by subtracting the change amount α from the low-pressure fuel pressure basic value PFLB as the target low-pressure fuel pressure basic value PFLTrB. Then, the CPU 61 temporarily ends the low-pressure fuel pressure target value derivation process M32.

On the other hand, in step S16, when the low-pressure fuel pressure target value PFTr is equal to the low-pressure fuel pressure base value PFLB (NO), the CPU 61 shifts the process to the next step S18. In step S18, the CPU 61 derives the low-pressure fuel pressure target value PFTr as the target low-pressure fuel pressure base value PFLTrB. Then, the CPU 61 temporarily ends the low-pressure fuel pressure target value derivation process M32.

The setting of the change amount α will be described.
The low-pressure fuel pressure PFL in each of the low-pressure delivery pipes 33A and 33B pulsates due to the drive of the high-pressure fuel pump 38. When a high-pressure fuel pump is provided for each high-pressure delivery pipe, the pulsation cycle caused by the drive of one high-pressure fuel pump is shifted by almost half a cycle from the pulsation cycle caused by the drive of the other high-pressure fuel pump by design. be able to. As a result, the pulsation caused by the drive of one high-pressure fuel pump can be offset by the pulsation caused by the drive of the other high-pressure fuel pump, so that the magnitude of the pulsation of the low-pressure fuel pressure PFL can be suppressed to a small size.

On the other hand, when there is only one high-pressure fuel pump 38 as in the present embodiment, the magnitude of the pulsation of the low-pressure fuel pressure PFL caused by the driving of the high-pressure fuel pump 38 cannot be reduced by the above method. When the magnitude of the pulsation of the low-pressure fuel pressure PFL is large and the low-pressure fuel pressure target value PFTr does not change so much, a discrepancy between the port injection amount and the port injection amount target value QFP is unlikely to occur. On the other hand, when the low-pressure fuel pressure target value PFTr changes significantly, a discrepancy is likely to occur between the port injection amount and the port injection amount target value QFP. Therefore, a value that can suppress the deviation between the port injection amount and the port injection amount target value QFP within an allowable range is set as the change amount α.

Next, the operation and effect of this embodiment will be described with reference to FIG. 7.
Before the timing t11, the operating point of the internal combustion engine 10 is in a region different from the high load region R3, and it is not estimated that the fuel supply amount required value QF becomes equal to or more than the specified quantity QFA by executing the estimation process M31. Therefore, in the low-pressure fuel pressure target value derivation process M32, the first basic value PFL1 is derived as the low-pressure fuel pressure basic value PFLB. Then, if there is no functional requirement or priority requirement, the low pressure fuel pressure target value PFTr is equal to the low pressure fuel pressure basic value PFLB.

At the timing t11, it is estimated that the fuel supply amount required value QF becomes equal to or more than the specified amount QFA by executing the estimation process M31. For example, when the required fuel supply amount QF gradually increases, when the operating point of the internal combustion engine 10 is in the high load region R3 and the fuel injection of the port injection valve 31 is stopped. By executing the estimation process M31, it is estimated that the required fuel supply amount QF becomes equal to or more than the specified amount QFA. Further, for example, in the case where the fuel supply amount required value QF suddenly increases, the fuel supply amount required value is executed by executing the estimation process M31 when the operating point of the internal combustion engine 10 is in a region different from the high load region R3. It will be estimated that the QF will be greater than or equal to the specified amount of QFA.

When it is estimated that the required fuel supply amount QF is equal to or larger than the specified amount QFA, the low pressure fuel pressure target value derivation process M32 derives the second basic value PFL2 as the low pressure fuel pressure basic value PFLB. At timing t11, the low pressure fuel pressure target value PFTr is lower than the low pressure fuel pressure base value PFLB. Therefore, the sum of the low-pressure fuel pressure target value PFTr and the change amount α is derived as the target low-pressure fuel pressure basic value PFLTrB. In the example shown in FIG. 7, there is no function request or priority request in the period from timing t11 to timing t12. Therefore, within the period, the low-pressure fuel pressure target value PFTr is equal to the target low-pressure fuel pressure base value PFLTrB. That is, the low-pressure fuel pressure target value PFTr is gradually increased at a rate corresponding to the change amount α.

In the present embodiment, the fuel supply amount required value QF becomes equal to or more than the specified amount QFA, and fuel injection is performed to both the port injection valve 31 and each in-cylinder injection valve 32 during high load operation of the internal combustion engine 10. Prior to this, the low pressure fuel pressure PFL in each of the low pressure delivery pipes 33A and 33B is increased. Therefore, with the low-pressure fuel pressure PFL in each of the low-pressure delivery pipes 33A and 33B increased, fuel injection of both the in-cylinder injection valve 32 and each port injection valve 31 can be performed during engine operation with a high load. it can.

Here, during high-load operation, the engine rotation speed NE is high, so that the intake valve 14 is open for a short time. Therefore, if the fuel injection period of the port injection valve 31 is long, there is a possibility that the fuel injection of the port injection valve 31 is still performed even if the intake valve 14 is closed. In this respect, in the present embodiment, the fuel injection of the port injection valve 31 can be completed before the intake valve 14 is closed because the low pressure fuel pressure PFL in each of the low pressure delivery pipes 33A and 33B is high.

Further, even during high load operation, not only the fuel injection of the in-cylinder injection valve 32 but also the fuel injection of the port injection valve 31 is performed. Therefore, the fuel injection amount of the in-cylinder injection valve 32 can be reduced as compared with the case where the fuel injection of the port injection valve 31 is not performed. As a result, the fuel injection of the in-cylinder injection valve 32 can be completed by the ignition timing.

As a result, it is possible to prevent a discrepancy between the amount of fuel actually supplied into the cylinder 11 and the required fuel supply amount QF due to the fuel injection of both the port injection valve 31 and the in-cylinder injection valve 32. Therefore, even when the internal combustion engine 10 performs high-load operation, the amount of fuel supplied into the cylinder 11 can be appropriately adjusted in one cycle of the internal combustion engine 10.

In the present embodiment, when the low-pressure fuel pressure target value PFTr is changed as described above, the low-pressure fuel pressure target value PFTr is changed at a speed corresponding to the change amount α. Therefore, when fuel is injected from the port injection valve 31 during the change of the low pressure fuel pressure target value PFTr, it is possible to suppress the deviation between the actual fuel injection amount of the port injection valve 31 and the port injection amount target value QFP.

In the example shown in FIG. 7, the functional requirement occurs at the timing t12 during the increase of the low pressure fuel pressure target value PFTr. When there is a functional requirement in this way, in the first arbitration process M33, a value corresponding to the functional requirement is set as the low pressure fuel pressure target value PFTra. As a result, the low pressure fuel pressure target value PFTr becomes equal to the low pressure fuel pressure target value PFTr. As a result, the low-pressure fuel pressure PFL in each of the low-pressure delivery pipes 33A and 33B can be quickly increased to a pressure according to the functional requirement.

At the subsequent timing t13, the function request disappears. Then, in the low-pressure fuel pressure target value derivation process M32, the target low-pressure fuel pressure base value PFLTrB is reduced from the low-pressure fuel pressure target value PFTr at the timing t13 at a speed corresponding to the change amount α. At this time, if there is no priority request, the low pressure fuel pressure target value PFTr is equal to the target low pressure fuel pressure base value PFLTrB.

By the way, since the estimated fuel supply amount required value QF is estimated to be equal to or higher than the specified amount QFA by the estimated processing M31, the fuel supply amount is requested by the estimated processing M31 after the second basic value PFL2 is set as the low pressure fuel pressure basic value PFLB. When it is no longer estimated that the value QF exceeds the specified amount QFA, the first basic value PFL1 is set as the low pressure fuel pressure basic value PFLB.

The above embodiment can be modified and implemented as follows. The above embodiment and the following modified examples can be implemented in combination with each other within a technically consistent range.
In the above embodiment, since the fuel supply amount required value QF is estimated to be equal to or higher than the specified amount QFA by the estimation process M31, the estimation process M31 sets the second basic value PFL2 as the low pressure fuel pressure basic value PFLB. When it is no longer estimated that the required fuel supply amount QF exceeds the specified amount QFA, the first basic value PFL1 is set as the low pressure fuel pressure basic value PFLB. However, even if it is no longer estimated that the fuel supply amount required value QF is equal to or more than the specified amount QFA, the second basic value PFL2 is used as the low pressure fuel pressure basic value PFLB while the fuel supply amount required value QF is equal to or more than the specified amount QFA. The set state may be maintained. In this case, if it is not estimated that the fuel supply amount required value QF is equal to or more than the specified amount QFA and both that the fuel supply amount required value QF is less than the specified amount QFA is satisfied, the low pressure fuel pressure basic value PFLB is set. The first basic value PFL1 will be set.

The internal combustion engine to which the fuel supply device 30 is applied does not have to be a V-type internal combustion engine as long as it has a plurality of banks. For example, the fuel supply device 30 may be applied to a horizontally opposed internal combustion engine.

The control device 60 includes one or more dedicated hardware circuits such as one or more processors that operate according to a computer program, dedicated hardware that executes at least a part of various processes, or a combination thereof. It can be configured as a circuit. As the dedicated hardware, for example, an ASIC which is an integrated circuit for a specific application can be mentioned. The processor includes a CPU and a memory such as a RAM and a ROM, and the memory stores a program code or an instruction configured to cause the CPU to execute a process. Memory, or storage medium, includes any available medium accessible by a general purpose or dedicated computer.

10 ... Internal combustion engine 11 ... Cylinder 151 ... Intake port 30 ... Fuel supply device 31 ... Port injection valve 32 ... In-cylinder injection valve 33A, 33B ... Low pressure delivery pipe 34A, 34B ... High pressure delivery pipe 36 ... Low pressure fuel pump 38 ... High pressure fuel Pump 60 ... Control device 300 ... Fuel tank

Claims (1)

Applies to internal combustion engines with multiple banks
A plurality of port injection valves provided for each cylinder of the internal combustion engine and injecting fuel into the intake port of the internal combustion engine.
A plurality of in-cylinder injection valves provided for each cylinder and injecting fuel into the cylinders.
A first low-pressure delivery pipe to which some of the port injection valves of the port injection valves are connected,
A second low-pressure delivery pipe to which the remaining port injection valves of the port injection valves are connected, and
A first high-pressure delivery pipe to which a part of the in-cylinder injection valves is connected,
A second high-pressure delivery pipe to which the remaining in-cylinder injection valve of the in-cylinder injection valve is connected, and
A low-pressure fuel pump that pumps fuel from the fuel tank and discharges it,
A high-pressure fuel pump that pressurizes and discharges the fuel discharged from the low-pressure fuel pump, and
A control device for controlling fuel injection of each port injection valve and fuel injection of each in-cylinder injection valve based on the operating point of the internal combustion engine is provided.
The fuel discharged from the low-pressure fuel pump is stored in each of the low-pressure delivery pipes, and the fuel discharged from the high-pressure fuel pump is stored in each of the high-pressure delivery pipes.
When the required value of the fuel supply amount into the cylinder in one cycle of the internal combustion engine is set as the fuel supply amount required value,
The control device is
An estimation process for estimating whether or not the required fuel supply amount becomes equal to or higher than a specified amount determined from the fuel discharge capacity of the high-pressure fuel pump due to high-load operation of the internal combustion engine.
When the estimated fuel supply amount requirement value is estimated to be equal to or more than the specified amount by the estimation process, the fuel supply amount requirement value in each of the low pressure delivery pipes is higher than when it is not estimated to be equal to or more than the specified amount. The low pressure increase process that controls the low pressure fuel pump so that the fuel pressure becomes high,
When the internal combustion engine performs high-load operation, when the required fuel supply amount is less than the specified amount, the in-cylinder injection valve is made to inject fuel, while the fuel injection of the port injection valve is stopped. A fuel supply device for an internal combustion engine that executes an injection process of injecting fuel from both the in-cylinder injection valve and the port injection valve when the required fuel supply amount is equal to or higher than the specified amount.

Images