JP2007187109A - Fuel injection control device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To restrain complication of a structure and enlargement of a device and to improve cooling performance in a fuel injection control device for an internal combustion engine. <P>SOLUTION: A fuel passage is provided for circulating fuel of a delivery pipe 14 adjacently to an injection port 45 formed on an end of an injector 13 and then returning the fuel to the delivery pipe 14, and the injection port 45 capable of injecting a part of the fuel flowing through the fuel passage is provided. When restarting fuel injection by a high pressure injector 13a from a fuel injection state only by a low pressure injector 13b, forcible circulation of the fuel to the fuel passage by the high pressure injector 13a is stopped, and fuel injection by the high pressure injector 13a is temporarily stopped until a fuel pressure P of the high pressure delivery pipe 14a is higher than a predetermined fuel pressure P<SB>1</SB>, and fuel injection by the low pressure injector 13b is performed. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a fuel injection control device for an internal combustion engine that can inject a predetermined amount of fuel into a combustion chamber or an intake port.

  2. Description of the Related Art Conventionally, a direct injection internal combustion engine that directly injects fuel into a combustion chamber instead of an intake port is known. In this in-cylinder internal combustion engine, when the intake valve is opened, air is drawn into the combustion chamber from the intake port and compressed by the piston, and fuel is directly injected from the injector into the high-pressure air. And the mist fuel are mixed, and the mixture is led to the spark plug, ignites and explodes, and driving force can be obtained.When the exhaust valve is opened, the exhaust gas after combustion is discharged from the exhaust port. Discharged.

  In such an in-cylinder injection internal combustion engine, the injector is supported so that the needle valve is movable in a housing having an injection port at the tip, and this needle valve is urged and supported so as to close the fuel passage. At the same time, when the solenoid is energized, the needle valve is moved by the electromagnetic force to open the fuel passage. Then, by moving the needle valve at a predetermined timing to open the fuel passage, the fuel in the fuel passage can be injected from the injection port toward the combustion chamber.

  In an injector applied to this direct injection internal combustion engine, a predetermined amount of fuel is maintained in a pressurized state, and fuel of a predetermined pressure is injected from the injection port during a period when the fuel passage is opened by the needle valve. The Therefore, even when the fuel injection period elapses and the needle valve closes the fuel passage, not all the fuel is injected into the combustion chamber, but a part of the fuel adheres to the periphery of the injection port and remains. In this case, the remaining fuel is steamed by the combustion gas generated in the combustion chamber, and is deposited as a deposit on the inner surface of the injection port or the tip surface of the needle valve. Then, the accumulated deposit narrows the flow passage area of the fuel passage and becomes a flow passage resistance of the fuel, which causes a decrease in the flow rate, varies the fuel injection amount, and deteriorates combustion.

  If fuel remains in the vicinity of the injection port, even if the fuel passage is opened by the needle valve in the next fuel injection period, all of the fuel injected by the remaining fuel is atomized. Insufficient, the atomization level at the initial stage of injection is not good, and problems such as torque fluctuations and exhaust gas characteristics are deteriorated during idle operation.

  In order to solve such a problem, it is considered that the tip of the injector is cooled to suppress deposit accumulation. For example, there are techniques described in Patent Documents 1 and 2 below. The cooling device for the injection nozzle described in Patent Document 1 closes the valve seat side of the outer cylinder of the needle valve and closes the upper part of the inner wall of the outer cylinder by engaging the outer wall of the inner cylinder. And a cylindrical shaft hole are formed as a cooling fuel passage that reciprocates inside the needle valve, and the inner cylinder passes through a pore provided in the outer wall of the outer cylinder on the sliding seal portion side from the low pressure fuel inlet. The inside of the needle valve is cooled by allowing low-pressure fuel to pass through the passage leading to the shaft hole above.

  The fuel injection valve of the internal combustion engine described in Patent Document 2 enables fuel to be supplied from the high-pressure fuel supply passage to the oil sump chamber, and the fuel in the oil sump chamber passes through the fuel oil circulation passage and the fuel oil passage. The fuel injection valve can be cooled by discharging, and at the time of fuel injection, the oil reservoir chamber and the injection hole are communicated and the fuel oil passage is closed to inject the fuel in the oil storage chamber from the injection hole. is there.

JP-A-7-301166 JP-A-8-200193

  However, the conventional injection nozzle cooling device described in Patent Document 1 described above is provided with a high-pressure fuel passage for injecting fuel from the injection hole, and for circulating the low-pressure fuel separately from the high-pressure fuel passage. And a cooling fuel passage. Therefore, a large number of fuel passages are required in the injector, which not only complicates the structure but also increases the size of the injector itself. Moreover, in the fuel injection valve of the conventional internal combustion engine described in Patent Document 2, normally, at the time of fuel injection, the fuel injection valve is discharged by discharging the fuel in the oil sump chamber through the fuel oil circulation path and the fuel oil passage. During cooling and fuel injection, the fuel oil passage is closed and the fuel in the oil reservoir is injected from the injection hole. Therefore, at the time of fuel injection, the fuel injection valve cannot be cooled, and the cooling performance is deteriorated.

  The present invention is intended to solve such problems, and provides a fuel injection control device for an internal combustion engine that improves the cooling performance while suppressing the complexity of the structure and the size of the device. With the goal.

  In order to solve the above-described problems and achieve the object, a fuel injection control device for an internal combustion engine of the present invention includes a low-pressure fuel injection device that injects fuel into an intake port, and a high-pressure fuel injection device that injects fuel into a combustion chamber. An internal combustion engine fuel injection control device capable of selectively driving the low-pressure fuel injection device or the high-pressure fuel injection device in accordance with the operating state of the internal combustion engine, wherein the low-pressure fuel injection device and the high-pressure fuel injection device The fuel injection device includes: a fuel injection port provided at a tip portion of the injection device body; a fuel passage capable of circulating fuel to the vicinity of the fuel injection port and then discharging the fuel; and the fuel passage and the fuel injection port. And a fuel circulation means for forcibly circulating the fuel in the fuel passage, and the control means includes: High pressure fuel injection When the apparatus is stopped, the fuel circulating means is driven to circulate the fuel to the vicinity of the fuel injection port by the fuel passage in the low pressure fuel injection apparatus and the high pressure fuel injection apparatus, and the high pressure fuel injection apparatus starts to be driven. Sometimes, the drive of the fuel circulation means is stopped, and the low pressure fuel injection device is driven until the fuel pressure of the high pressure fuel injection device becomes higher than a predetermined fuel pressure set in advance.

  In the fuel injection control device for an internal combustion engine of the present invention, by forming the injection valve in a hollow shape, an internal passage is formed inside the injection valve and an external passage is formed outside the injection valve. A communication hole for communicating the internal passage and the external passage is formed at the tip of the injection valve, and the fuel passage is constituted by the internal passage, the external passage, and the communication hole.

  In the fuel injection control device for an internal combustion engine according to the present invention, the high pressure fuel injection device is configured such that a fuel supply pipe having a high pressure fuel pump is connected to one end of the high pressure delivery pipe, and a high pressure is connected to the other end of the high pressure delivery pipe. A fuel discharge pipe having a relief valve is connected, and the control means reduces the set pressure of the high pressure relief valve as the fuel circulation means when the high pressure fuel injection device is stopped, thereby The fuel supplied to the high-pressure delivery pipe is circulated through the fuel passage and then discharged to the fuel discharge pipe through the high-pressure delivery pipe.

  In the fuel injection control device for an internal combustion engine according to the present invention, the low pressure fuel injection device is configured such that a fuel supply pipe having a low pressure fuel pump is connected to one end of the low pressure delivery pipe, while a low pressure is connected to the other end of the low pressure delivery pipe. A fuel discharge pipe having a relief valve is connected, and the control means stops the high-pressure fuel pump and lowers the set pressure of the high-pressure relief valve when the high-pressure fuel injection device is stopped, so that the low-pressure fuel pump The pressurized fuel is circulated in the fuel passage in the high-pressure fuel injection device.

  According to the fuel injection control device for an internal combustion engine of the present invention, a low-pressure fuel injection device that injects fuel into the intake port and a high-pressure fuel injection device that injects fuel into the combustion chamber are provided, depending on the operating state of the internal combustion engine. The control means can selectively drive the low-pressure fuel injection device or the high-pressure fuel injection device. In the low-pressure fuel injection device and the high-pressure fuel injection device, a fuel injection port is provided at the tip of the injection device body, and the fuel is supplied to the fuel injection device. A fuel passage that circulates to the vicinity of the fuel injection port and then discharges to the outside is provided, and a part of the fuel flowing through the fuel passage can be injected from the fuel injection port by connecting the fuel passage and the fuel injection port by an injection valve. In addition, a fuel circulation means for forcibly circulating fuel in the fuel passage is provided, and the control means drives the fuel circulation means when the high-pressure fuel injection device is stopped, in the low-pressure fuel injection device and the high-pressure fuel injection device. The fuel is circulated to the vicinity of the fuel injection port by the fuel passage, and at the start of driving of the high pressure fuel injection device, the driving of the fuel circulation means is stopped and the fuel pressure of the high pressure fuel injection device is higher than a preset predetermined fuel pressure. The low-pressure fuel injection device is driven until it becomes.

  Therefore, in the low-pressure fuel injection device and the high-pressure fuel injection device, by composing the passage for injecting the fuel and the passage for cooling the tip of the injection device main body as the fuel passage, the structure becomes complicated and the device On the other hand, the cooling performance can be improved by constantly flowing the fuel in the fuel passage to cool the tip of the injector body, and the high-pressure fuel injector can be stopped. Sometimes, by circulating the fuel through the fuel passage in each fuel injection device by the fuel circulation means, it is possible to reliably cool the tip of the injection device body and suppress the temperature rise, while starting the drive of the high-pressure fuel injection device Sometimes, by driving the low pressure fuel injection device until the fuel pressure of the high pressure fuel injection device becomes higher than a predetermined fuel pressure set in advance, the deterioration of combustion due to the low pressure fuel injection in the high pressure fuel injection device Sealed, it is possible to suppress the deterioration of the performance degradation and the exhaust gas characteristics.

  Embodiments of a fuel injection control device for an internal combustion engine according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

  FIG. 1 is a schematic configuration diagram of a fuel injection control device for an internal combustion engine according to an embodiment of the present invention, FIG. 2 is a flowchart showing fuel injection control by the fuel injection control device for the internal combustion engine of the present embodiment, and FIG. FIG. 4 is a cross-sectional view taken along the line IV-IV in FIG. 3, FIG. 5 is a cross-sectional view taken along the line V-V in FIG. 4, and FIG. FIG. 7 is a cross-sectional view of a tip portion of an injector in a fuel injection control device for an internal combustion engine of an example, FIG. 7 is a cross-sectional view taken along the line VII-VII in FIG. 6, and FIG.

  The fuel injection control device for an internal combustion engine according to the present embodiment includes a low pressure fuel injection device that injects fuel into an intake port and a high pressure fuel injection device that injects fuel into a combustion chamber, depending on the operating state of the internal combustion engine. The low pressure fuel injection device or the high pressure fuel injection device can be selectively driven. That is, as shown in FIG. 1, an engine 10 as an internal combustion engine is an in-cylinder spark-ignition multi-cylinder engine, and is provided with combustion chambers 11 corresponding to four cylinders. Are equipped with a high-pressure injector 13a for directly injecting fuel into each combustion chamber 11 and a spark plug (not shown). Each high-pressure injector 13a has a base end connected to the high-pressure delivery pipe 14a, and can inject high-pressure fuel in the high-pressure delivery pipe 14a into the combustion chamber 11.

  Further, the engine 10 is provided with an intake port 15 communicating with the combustion chamber 11 of each cylinder, and the cylinder head 12 is equipped with a low-high pressure injector 13b for injecting fuel into each intake port 15. . Each low pressure injector 13b has a base end connected to the low pressure delivery pipe 14b, and can inject the low pressure fuel in the low delivery pipe 14b into the intake port 15.

  The fuel tank 16 can store a predetermined amount of fuel, and a low-pressure feed pump 17 is mounted therein. The low-pressure feed pump 17 is connected to a high-pressure pump (high-pressure fuel pump) 19 via a first fuel supply pipe 18a. The high-pressure pump 19 is connected to one end of the high-pressure delivery pipe 14a via a second fuel supply pipe 18b. It is connected. The high-pressure pump 19 can be driven by a camshaft 20, and a check valve 21 is mounted on the second fuel supply pipe 18b. The first fuel supply pipe 18 a is provided with a return pipe 22 for returning the fuel to the fuel tank 16, and a check valve 23 is attached to the return pipe 22. The other end of the high-pressure delivery pipe 14a is connected to the base end of the first fuel discharge pipe 24a, and the tip of the first fuel discharge pipe 24a is connected to the fuel tank 16, and this fuel discharge An electromagnetic relief valve 25a is attached to the pipe 24a.

  On the other hand, the third fuel supply pipe 18c branched from the first fuel supply pipe 18a is connected to one end of the low pressure delivery pipe 14b, and the other end of the low pressure delivery pipe 14b is connected to the base end of the second fuel discharge pipe 24b. And the tip of the second fuel discharge pipe 24b is connected to the first fuel discharge pipe 24a, and an electromagnetic relief valve 25b is mounted on the second fuel discharge pipe 24b.

  In the high pressure pump 19, as shown in FIG. 8, a plunger 102 is movably supported on the casing 101, and a pressure chamber 103 for pressurizing fuel is formed. The plunger 102 is urged and supported in a direction in which the pressure chamber 103 expands by a spring (not shown), and is pressed by a cam 104 formed on the camshaft 20 to reduce the pressure chamber 103. An upper portion of the casing 101 is formed with an intake port 105 that communicates with the first fuel supply pipe 18a and sucks low-pressure fuel, and a discharge port 106 that discharges pressurized fuel to the second fuel supply pipe 18b. ing. In addition, a metering valve 107 for opening and closing the suction port 105 is provided at the upper part of the casing 101. This metering valve 107 is an electromagnetic spill valve, and can close the suction port 105 when energized.

  Therefore, when the camshaft 20 rotates and the plunger 102 is lowered by the cam 104, if the intake port 105 is opened by the metering valve 107, the low pressure fuel can be sucked into the pressure chamber 103, and the camshaft 20 rotates. When the plunger 102 is raised by the cam 104 and the intake port 105 is closed by the metering valve 107, the low-pressure fuel in the pressure chamber 103 is pressurized to a predetermined pressure and can be pumped from the discharge port 106.

  By driving the low-pressure feed pump 16 in the fuel injection device of the internal combustion engine of the present embodiment configured as described above, the fuel in the fuel tank 16 is pressurized to a low pressure and supplied to the fuel supply pipes 18a and 18c. The low pressure fuel can be supplied to the low pressure delivery pipe 14b. Further, by driving the high pressure pump 19, the low pressure fuel in the first fuel supply pipe 18a can be pressurized to a high pressure and supplied to the second fuel supply pipe 18b, and the high pressure fuel can be supplied to the high pressure delivery pipe 14a. Then, surplus fuel in the delivery pipes 14 a and 14 b can be discharged to the fuel discharge pipes 24 a and 24 b and returned to the fuel tank 16.

  Returning to FIG. 1, an electronic control unit (ECU) 26 is mounted on the vehicle, and the ECU 26 can control the injectors 13 a and 13 b. That is, the ECU 26 is connected with an air flow sensor 27, a throttle position sensor 28, an accelerator position sensor 29, an engine speed sensor 30, a water temperature sensor 31, and the like. Therefore, the ECU 26 determines the fuel injection amount, the injection timing, and the like based on the engine operating state such as the intake air amount detected by the sensors 26 to 31, the throttle opening, the accelerator opening, the engine speed, and the engine coolant temperature. ing.

  Further, the ECU 26 determines whether to inject fuel into the combustion chamber 11 by the high pressure injector 13a, to the intake port 15 by the low pressure injector 13b, or both, based on the operating state of the engine 10. Yes. For example, during the start-up warm-up operation of the engine 10, the wall surface of the combustion chamber 11 is not sufficiently heated, and fuel may not be atomized properly and may adhere to the wall surface and burn incompletely. The fuel injection into the combustion chamber 11 is stopped and only the fuel injection into the intake port 15 is executed. After the engine is warmed up, the high-pressure fuel injection amount into the combustion chamber 11 and the low-pressure fuel injection amount into the intake port 15 are set based on the engine speed and the engine load. In general, only the high-pressure fuel injection amount into the combustion chamber 11 is executed in the low-rotation low-load region of the engine 10, and the high-pressure fuel injection amount into the combustion chamber 11 and the intake port 15 in the middle-rotation middle load region. It is desirable to execute only the low pressure fuel injection amount to the intake port 15 in the high rotation and high load region.

  The high pressure delivery pipe 14a is provided with a fuel pressure sensor 32a for detecting the fuel pressure, and the low pressure delivery pipe 14b is provided with a fuel pressure sensor 32b for detecting the fuel pressure. The detected fuel pressure is supplied to the ECU 26. Output. The ECU 26 drives and controls the low-pressure feed pump 17 and the high-pressure pump 19 so that the fuel pressure in the delivery pipes 14a and 14b becomes a predetermined pressure. Furthermore, each electromagnetic relief valve 25a, 25b is normally configured to function as a mechanical relief valve, and when the fuel pressure in each delivery pipe 14a, 14b exceeds a predetermined pressure, the electromagnetic relief valve 25a, 25b. Is automatically opened, the fuel in the delivery pipes 14a and 14b is discharged to the fuel discharge pipes 24a and 24b, and the fuel pressure in the delivery pipes 14a and 14b is maintained at a predetermined pressure.

  Here, the high-pressure injector 13a and the low-pressure injector 13b described above will be described in detail. Since the injectors 13a and 13b have substantially the same structure, only the high-pressure injector 13a will be described in detail.

  In the high-pressure injector 13a, as shown in FIGS. 4 to 8, a valve body 42 is fixed to a distal end portion of a holder 41 having a hollow shape, and the valve body 42 is formed with a tapered hollow portion 43 therein. In addition, a sac portion 44 having a spherical shape is formed continuously at the distal end side of the hollow portion 43, and an injection port 45 communicating from the sack portion 44 to the outside is formed. A hollow magnetic pipe 46 is fixed to the rear end portion of the holder 41, and a cylindrical core 47 is fitted and fixed in the magnetic pipe 46. A cylindrical armature 48 is supported so as to be movable in the axial direction with a predetermined gap. The magnetic pipe 46 is configured such that a non-magnetic portion is positioned between magnetic portions positioned above and below, and the non-magnetic portion prevents the magnetism from being short-circuited with the upper and lower magnetic portions. In this case, the injection device main body is constituted by the holder 41, the valve body 42, the magnetic pipe 46, and the like.

  The needle valve 49 as an injection valve has a hollow shape, and is configured by integrally connecting a valve body 50 and a connecting portion 51. The needle valve 49 is disposed in the holder 41 and the valve body 42 so as to be movable in the axial direction, and the rear end portion of the connecting portion 51 is connected to the tip portion of the armature 48, while the valve main body 50. Is inserted into the hollow portion 43 of the valve body 42 with a gap at a predetermined interval in the circumferential direction. The needle valve 49 has a seal portion 52 formed at the tip, while the needle valve 49 is placed on the tip side between the adjust pipe 53 and the armature 48 mounted in the core 47 via the armature 48. An urging compression coil spring 54 is interposed, and the needle valve 49 is urged and supported so that the seal portion 52 abuts the valve seat portion 55 of the valve body 42.

  A coil 57 is wound around the outside of the magnetic pipe 46 via a bobbin 56, a connector 58 is formed on the outside of the coil 57 by resin molding, and a yoke 59 made of a magnetic material is fixed to the outside of the connector 58. Yes. In this case, the injection coil moving means is constituted by the compression coil spring 54, the core 47, the armature 48, the bobbin 56, the coil 57, the connector 58, the yoke 59, and the like. Accordingly, when the coil 57 is energized, an electromagnetic attractive force is generated in the core 47, and the armature 48 and the needle valve 49 are moved to the rear end side (upper side in FIGS. 4 and 8) against the urging force of the compression coil spring 54. The seal portion 52 can be moved away from the valve seat portion 55 of the valve body 42. In this case, when the seal portion 52 of the needle valve 49 is in close contact with the valve seat portion 55 of the valve body 42, a gap S is set between the core 47 and the armature 48, and the needle valve 49 It can move to the rear end side by S, and this clearance S becomes the lift amount of the needle valve 49.

  In addition, a fuel introduction pipe 60 is connected to the rear end portion of the magnetic pipe 46, and a relief pipe 61 is connected to the rear end portion of the core 47, and the fuel introduction pipe 60 and the relief pipe 61 are interposed between them. A fuel filter 62 is attached.

  The high pressure injector 13a of the present embodiment is provided with a fuel passage through which fuel supplied from the outside is circulated to the vicinity of the injection port 45 and then discharged to the outside. The needle valve 49 connects the fuel passage and the injection port 45 to each other. The fuel passage and the injection port 45 communicate with each other, and a part of the fuel flowing through the fuel passage can be injected from the injection port 45.

  That is, when the needle valve 49 has a hollow shape, an internal passage 63 is formed inside the needle valve 49, and an external passage 64 is formed outside the needle valve 49. Two communication holes 65 for communicating the passage 63 and the external passage 64 are formed. In this case, the two communication holes 65 are formed at the tip end portion of the needle valve 49 at equal intervals in the circumferential direction. Further, the core 47 and the armature 48 constituting the injection valve moving means have a cylindrical shape, so that central passages 66 and 67 are formed at the center thereof, and at the outer periphery of the core 47 and the armature 48 in the axial direction. Through-holes 70 and 71 are formed by forming the notches 68 and 69 along the lines. Further, a fuel supply path 72 is formed between the fuel introduction pipe 60 and the relief pipe 61, and a fuel discharge path 73 is formed in the relief pipe 61.

  On the other hand, as shown in FIG. 1, the high-pressure delivery pipe 14a is partitioned into a first chamber 75 and a second chamber 76 by a partition wall 74, and the first chamber 75 has a second fuel supply pipe 18b at the base end. Are connected to close the distal end portion, while the second chamber 76 is closed at the proximal end portion, and the first fuel discharge pipe 24a is connected to the distal end portion. In this case, the fuel pressure sensor 32a detects the fuel pressure on the first chamber 75 side. As shown in FIG. 4, the fuel supply path 72 of the high pressure injector 13a communicates with the first chamber 75 of the high pressure delivery pipe 14a, while the fuel discharge path 73 communicates with the second chamber 76.

  Accordingly, high-pressure fuel is supplied from the first chamber 75 of the high-pressure delivery pipe 14a to the fuel supply passage 72 of the high-pressure injector 13a, through the cores 47 and the armature 48 through passages 70 and 71, the external passage 64 of the needle valve 49, and the communication hole 65. A fuel passage that is discharged to the second chamber 76 of the high-pressure delivery pipe 14a through the inner passage 63, the core 47 and the central passages 66 and 67 of the armature 48, and the fuel discharge passage 73 is formed.

  And the holder 41 which comprises an injection device main body is fixed at the front-end | tip outer peripheral part to the attachment hole 12a of the cylinder head 12 via the gas seal 77, and the fuel passage mentioned above is extended from the gas seal 77 to the front end side of the holder 41. Has been. Further, the end of the fuel introduction pipe 60 as the fuel supply side end of the fuel passage is connected to the flange portion 33 of the delivery pipe 14 via the O-ring 78, and the relief pipe 61 as the fuel discharge side end of the fuel passage. Is connected to the partition wall 74 through an O-ring 79.

  In the fuel injection control device of the internal combustion engine of the present embodiment configured as described above, the ECU 26 detects the fuel based on the fuel pressure in the high pressure delivery pipe 14a and the low pressure delivery pipe 14b detected by the fuel pressure sensors 32a and 32b. The low pressure feed pump 17 and the high pressure pump 19 are driven and controlled so that the pressure becomes a predetermined pressure, and the intake air amount, throttle opening, accelerator opening, engine speed, engine cooling water temperature detected by the sensors 27 to 31 are controlled. The high-pressure fuel injection amount, the low-pressure fuel injection amount, the injection timing, and the like are determined based on the engine operating state, and the high-pressure injector 13a and the low-pressure injector 13b are driven and controlled.

  That is, when a fuel injection command is output from the ECU 26 to the injectors 13a and 13b and the coils 57 of the injectors 13a and 13b are energized, the needle valve 49 is moved by a predetermined lift amount S by the electromagnetic attraction force. By separating the seal portion 52 from the valve seat portion 55 of the valve body 42, the external passage 64 and the injection port 45 that constitute the fuel passage are communicated. In this case, the first chamber 75 of the delivery pipes 14a and 14b includes the fuel supply passage 72, the through passages 70 and 71 of the injectors 13a and 13b, the external passage 64, the communication hole 65, the internal passage 63, the central passages 66 and 67, the fuel. The fuel pressure is maintained at a predetermined pressure by communicating with the second chamber 76 via the discharge path 73.

  Accordingly, when the needle valve 49 moves and the external passage 64 and the injection port 45 communicate with each other, a part of the predetermined pressure fuel in the external passage 64 is supplied to the sac portion 44, and the fuel in this sac portion 44 is supplied from the injection port 45. The fuel is injected into the combustion chamber 11 or the intake port 15. At this time, since the fuel in the fuel passages in the injectors 13a and 13b decreases, the fuel is supplied from the fuel supply pipes 18b and 18c to the first chamber 75 of the delivery pipes 14a and 14b, and the fuel in the first chamber 75 is supplied. Is supplied from the fuel supply passage 72 to the injectors 13a and 13b and circulates through the through passages 70 and 71 and the external passage 64 to the vicinity of the injection port 45, thereby reliably cooling the tip of the holder 41 and the valve body 42. can do.

  By the way, as described above, the ECU 26 injects fuel into the combustion chamber 11 by the high-pressure injector 13a, injects into the intake port 15 by the low-pressure injector 13b, or both in accordance with the operating state of the engine 10. Have decided. However, when fuel is injected only into the intake port 15 by the low pressure injector 13b, the high pressure injector 13a does not inject fuel, and the fuel in the fuel passage in the high pressure injector 13a does not decrease, so the high pressure delivery pipe from the second fuel supply pipe 18b. 14 a is not supplied with fuel, and the fuel in the first chamber 75 is circulated to the vicinity of the injection port 45 to sufficiently cool the tip of the holder 41 and the valve body 42, so that the operating state of the engine 10 In some cases, deposits may be deposited.

  Therefore, in the fuel injection control device for the internal combustion engine of the present embodiment, when the fuel is injected only into the intake port 15 by the low pressure injector 13b and the fuel injection by the high pressure injector 13a is stopped, the ECU 26 serving as the control means includes the high pressure injector 13a. The fuel is forcibly circulated in the fuel passage.

  Further, in this embodiment, an electromagnetic relief valve 25a of the first fuel discharge pipe 24a connected to the second chamber 76 of the high pressure delivery pipe 14a is applied as a fuel circulation means for forcibly circulating fuel in the fuel passage in the high pressure injector 13a. is doing. Accordingly, when the ECU 26 forcibly circulates fuel in the fuel passage of the high pressure injector 13a, the ECU 26 reduces the set pressure of the electromagnetic relief valve 25a, thereby supplying the fuel in the second chamber 76 of the high pressure delivery pipe 14 to the fuel discharge pipe 24. The low-pressure fuel in the second fuel supply pipe 18a is supplied to the high-pressure delivery pipe 14a, and the fuel supplied to the high-pressure delivery pipe 14a can be circulated in the fuel passage of the high-pressure injector 14a.

  Further, while the fuel injection by the high pressure injector 13a is suspended, the low pressure fuel in the second fuel supply pipe 18a is supplied to the high pressure delivery pipe 14a by lowering the set pressure of the electromagnetic relief valve 25a. Is circulated in the fuel passage of the high-pressure injector 14a. Therefore, when the fuel injection by the high pressure injector 13a is resumed, even if the high pressure pump 19 is driven and the set pressure of the electromagnetic relief valve 25a is increased, a predetermined high pressure fuel pressure in the high pressure delivery pipe 14a can be secured immediately. The high pressure injector 14a cannot inject a fuel spray having a predetermined particle diameter into the combustion chamber 11, and the combustion deteriorates.

  Therefore, in the fuel injection control device for the internal combustion engine of the present embodiment, at the start of fuel injection by the high pressure injector 13a, the ECU 26 as the control means stops the forced circulation of fuel to the fuel passage in the high pressure injector 13a and The fuel injection by the high-pressure injector 13a is temporarily stopped until the fuel pressure in the delivery pipe 14a becomes higher than a predetermined fuel pressure set in advance, and instead, the fuel injection by the low-pressure injector 13b is executed.

  Here, the fuel injection control by the fuel injection control device of the internal combustion engine of the present embodiment will be specifically described based on the flowchart of FIG.

  As shown in FIG. 2, in step S11, the ECU 26 determines the fuel injection region (high pressure fuel injection amount and low pressure fuel injection amount) based on the engine operating state such as the throttle opening, the vehicle speed, the engine speed, and the engine coolant temperature. That is, it is set whether high pressure fuel is injected into the combustion chamber 11 by the high pressure injector 13a, low pressure fuel is injected into the intake port 15 by the low pressure injector 13b, or both. In step S12, it is determined whether the operating region of the engine 10 is in the operating region in which high pressure fuel is injected into the combustion chamber 11 by the high pressure injector 13a. Here, when it is determined by the high pressure injector 13a that there is no operating region for injecting high pressure fuel into the combustion chamber 11, port injection is executed in step S13, and fuel circulation control is executed in step S14.

  That is, in step S13, the low pressure injector 13b is driven to inject the low pressure fuel in the low pressure delivery pipe 14b into the intake port 15. Then, since the fuel in the fuel passage in the low pressure injector 13b decreases, the low pressure fuel is supplied from the second fuel supply pipe 18c to the low pressure delivery pipe 14b, and this low pressure fuel is supplied from the fuel supply path 72 to the low pressure injector 13b for injection. By circulating to the vicinity of the opening 45, the tip of the holder 41 and the valve body 42 can be reliably cooled.

  In step S14, the high-pressure pump 19 is stopped on the high-pressure injector 13a side, the set pressure of the electromagnetic relief valve 25a is reduced, and the high-pressure fuel in the second chamber 76 of the high-pressure delivery pipe 14a is discharged from the first fuel. By forcibly discharging to the pipe 24a, the low-pressure fuel in the second fuel supply pipe 18b is supplied to the high-pressure delivery pipe 14a, and the low-pressure fuel supplied to the high-pressure delivery pipe 14a is circulated through the fuel passage of the high-pressure injector 13a. . In this case, even when the high-pressure pump 19 is stopped, the low-pressure fuel can be supplied to the high-pressure injector 13a by opening the metering valve 107. Further, by controlling the discharge amount of the low-pressure feed pump 17, the fuel circulation amount in the fuel passages of the injectors 13a and 13b can be adjusted.

  Specifically, when the high-pressure fuel injection by the high-pressure injector 13a is stopped, the coil 57 of the high-pressure injector 13a is in a non-energized state. By closely contacting the valve seat portion 55 of the valve body 42, the external passage 64 constituting the fuel passage and the injection port 45 are blocked without being communicated with each other. In this state, when the set pressure of the electromagnetic relief valve 25 is decreased, the high pressure fuel in the second chamber 76 of the high pressure delivery pipe 14a is discharged to the first fuel discharge pipe 24a, and the low pressure fuel in the second fuel supply pipe 18b is discharged. It is supplied to the first chamber 75 of the high pressure delivery pipe 14a. Therefore, the low pressure fuel supplied to the first chamber 75 is supplied from the fuel supply path 72 to the high pressure injector 13a, and the through paths 70 and 71, the external passage 64, the communication hole 65, the internal passage 63, and the central passages 66 and 67. The fuel is discharged from the fuel discharge passage 73 to the second chamber 76 of the high pressure delivery pipe 14a, and the low pressure fuel is forced to circulate to the vicinity of the injection port 45 of the high pressure injector 13a. Even without fuel injection, the tip of the holder 41 and the valve body 42 can be reliably cooled by the circulating fuel.

  On the other hand, when it is determined in step S12 that the operating state of the engine 10 is in an operating region in which high pressure fuel is injected into the combustion chamber 11 by the high pressure injector 13a, the fuel circulation control is stopped in step S15. That is, the high pressure pump 19 is driven on the high pressure injector 13a side, and the set pressure of the electromagnetic relief valve 25a is increased to a pressure at which high pressure fuel can be injected, so that the high pressure in the second chamber 76 of the high pressure delivery pipe 14a is increased. The forced discharge of the fuel to the first fuel discharge pipe 24a is stopped.

Subsequently, at step S16, whether higher than a predetermined fuel pressure P ₁ of the fuel pressure P is set in advance in the high-pressure delivery pipe 14a determines. The predetermined fuel pressure P ₁ is a fuel pressure at which the high-pressure injector 13a can inject high-pressure fuel into the combustion chamber 11 by spraying with a predetermined particle size. Then, in step S16, when the fuel pressure P is equal to or less than the predetermined fuel pressure P _1, at step S17, without executing the fuel injection by the high-pressure delivery pipe 14a, fuel injection by the low-pressure injector 13b Execute. That is, after it is determined by the high pressure injector 13a that it is in the operation region where high pressure fuel is injected into the combustion chamber 11, the high pressure pump 19 is driven and the set pressure of the electromagnetic relief valve 25a is changed, and the fuel in the high pressure delivery pipe 14a is changed. Until the pressure P rises to the predetermined fuel pressure P ₁ , the low pressure injector 13 b injects an amount of fuel that the high pressure injector 13 a should inject into the combustion chamber 11 or a corresponding amount of fuel into the intake port 15.

Then, in step S16, when the fuel pressure P is determined it is higher than a predetermined fuel pressure P _1, at step S18, stops the fuel injection by the low-pressure delivery pipe 14b, or and reduced injection volume, high pressure Fuel injection is performed by the injector 13a. That is, the high-pressure injector 13 a injects an amount of fuel that the high-pressure delivery pipe 14 a should inject into the combustion chamber 11 into the combustion chamber 11 as it is. Therefore, until the fuel pressure P in the high-pressure delivery pipe 14a is increased to a predetermined fuel pressure P _1, since the low-pressure injector 13b is fuel injected into the intake port 15, high-pressure delivery pipe 14a is a fuel spray having a predetermined particle size into the combustion chamber 11 Can be injected, and deterioration of combustion is prevented.

  As described above, in the fuel injection control device for the internal combustion engine of the present embodiment, the high pressure injector (high pressure fuel injection device) 13a that injects fuel into the combustion chamber 11 and the low pressure injector (low pressure) that injects fuel into the intake port 15. Fuel injectors) 13b, and the injectors 13a and 13b are connected to the delivery pipes 14a and 14b at the base ends of the injectors 13a and 13b. The injectors 13a and 13b are connected to the fuel of the delivery pipes 14a and 14b. Is provided in the vicinity of the injection port 45 formed at the tip of the valve body 42 and then returned, and the fuel valve and the injection port 45 are shut off by the needle valve 49 so that fuel is supplied in the vicinity of the injection port 45. The fuel passage and the injection port 45 are communicated with each other, and a part of the fuel flowing through the fuel passage is communicated from the injection port 45. Thereby making it possible injection in baking chamber 11.

  Accordingly, at the time of fuel injection, the fuel passage and the injection port 45 are communicated by the needle valve 49, the fuel in the delivery pipes 14a and 14b circulates to the vicinity of the injection port 45 through the fuel passage, and a predetermined amount of fuel is supplied at a predetermined pressure. The fuel can be injected only from the injection port 45 into the combustion chamber 11, and the surplus fuel returns to the delivery pipes 14a and 14b, so that the vicinity of the injection port 45 is reliably cooled by the fuel circulating in the injectors 13a and 13b. Can do. As a result, by sharing the fuel passage and the passage for cooling the vicinity of the injection port 45 as the fuel passage, the structure can be simplified and the apparatus can be downsized. On the other hand, the fuel can always flow in the fuel passage to cool the vicinity of the injection port 45, and the cooling performance of the injector 13 can be improved.

  Further, even when the fuel injection into the combustion chamber 11 by the high pressure injector 13a is stopped, the fuel circulation control to the high pressure injector 13a is executed. That is, the set pressure of the electromagnetic relief valve 25a is reduced, and the fuel in the second chamber 76 of the high pressure delivery pipe 14a is forcibly discharged to the first fuel discharge pipe 24a, whereby the low pressure fuel in the second fuel supply pipe 18b is obtained. Is supplied to the high pressure delivery pipe 14a, and the low pressure fuel supplied to the high pressure delivery pipe 14a is circulated through the fuel passage of the high pressure injector 13a.

  Therefore, even when the high-pressure injector 13a has stopped fuel injection, the set pressure of the electromagnetic relief valve 25a is reduced to supply and discharge fuel to the high-pressure delivery pipe 14a, and low-pressure fuel is injected into the high-pressure injector 13a. Circulation is forced to the vicinity of the opening 45, and the tip of the holder 41 and the valve body 42 can be reliably cooled by this circulating fuel.

  As a result, regardless of the operating state of the high-pressure injector 13a, the fuel can always flow in the fuel passage and the vicinity of the injection port 45 can be cooled, and even if the fuel remains in the vicinity of the injection port 45, the remaining fuel remains. Steaming is not performed, and deposition of deposits on the inner surface of the injection port 45 can be reliably suppressed. Therefore, variations in fuel injection amount and deterioration in combustion can be suppressed. Further, by constantly circulating the fuel in the fuel passage, the bubbles generated in the fuel are discharged, so that the startability can be prevented from being deteriorated and the idling operation can be stabilized. .

Further, in the fuel injection control device for the internal combustion engine of the present embodiment, when the fuel injection by the high pressure injector 13a is resumed from the fuel injection state by only the low pressure injector 13b, the forced circulation of the fuel to the fuel passage in the high pressure injector 13a is performed. It is stopped, until the fuel pressure P in the high-pressure delivery pipe 14a is higher than a predetermined fuel pressure P _1, to pause the fuel injection by the high-pressure injectors 13a, so that to perform the fuel injection by the low pressure injector 13b.

Therefore, since the fuel pressure P in the high-pressure delivery pipe 14a becomes higher than a predetermined fuel pressure P _1, by executing the fuel injection into the combustion chamber 11 by the high-pressure injectors 13a, the high-pressure injectors 13a within the combustion chamber 11 to the low pressure fuel Combustion deterioration due to injection can be prevented, and deterioration of engine performance and exhaust gas characteristics can be suppressed.

  In this embodiment, the high-pressure injector 13a is applied to the in-cylinder injection engine 10 that directly injects fuel into the combustion chamber 11, and the outer peripheral portion of the tip of the holder 41 is connected to the mounting hole 12a of the cylinder head 12 via a gas seal 77. The fuel passage extends from the gas seal 77 to the tip side. Therefore, even if the fuel remaining in the vicinity of the injection port 45 is steamed by the combustion gas generated in the combustion chamber 11, the remaining fuel is cooled by the fuel circulating in the fuel passage. It is possible to reliably suppress the deposition of deposits.

  Further, in the fuel injection control device for the internal combustion engine of the present embodiment, the needle valve 49 is formed into a hollow shape, so that an internal passage 63 is formed inside the needle valve 49 and at the outside of the needle valve 49. An external passage 64 is formed, and the internal passage 63 and the external passage 64 are communicated by a communication hole 65 formed at the tip of the needle valve 49. The internal passage 63, the external passage 64, and the communication hole 65 are used as a fuel passage. Yes. Therefore, the fuel passage can be configured without increasing the size of the holder 41, the valve body 42, etc., and the apparatus can be reduced in size. In this case, by forming the two communication holes 65 at the tip end portion of the needle valve 49 at equal intervals in the circumferential direction, it is possible to prevent the flow of fuel flowing from the internal passage 63 to the external passage 64 and to inject by circulating fuel. The vicinity of the mouth 45 can be cooled uniformly in the circumferential direction.

  Further, in the fuel injection control device for the internal combustion engine of the present embodiment, the core 47 and the armature 48 are formed in a cylindrical shape, so that the central passages 66 and 67 are formed at the center thereof, and the core 47 and the armature 48 are formed. Cutout portions 68 and 69 along the axial direction are formed in the outer peripheral portion of the pier, and through passages 70 and 71 are provided. The central passages 66 and 67 and the through passages 70 and 71 are used as fuel passages. Therefore, the fuel passage can be formed without increasing the size of the core 47, the armature 48, etc. that constitute the injection valve moving means, and the apparatus can be downsized.

  In this case, the fuel in the high pressure delivery pipe 14 a is supplied from the fuel supply passage 72 to the injector 13, and passes through the core 47 and the through passages 70 and 71 outside the armature 48 and the external passage 64 of the needle valve 49 and in the vicinity of the injection port 45. From the communication hole 65, the fuel is discharged from the fuel discharge passage 73 to the delivery pipe 14 through the internal passage 63 of the needle valve 49, the central passages 66 and 67 inside the core 47 and the armature 48. Accordingly, the fuel is received by the holder 41 and the valve body 42 in the forward path of the fuel passage, and is radiated by the needle valve 49 and the like in the backward path, thereby reducing the temperature difference between the holder 41 and the valve body 42 and the needle valve 49. Variations in the fuel injection amount due to expansion of the injection port 45 and contraction of the needle valve 49 can be suppressed.

  In addition, the inside of the delivery pipes 14 a and 14 b is partitioned into a first chamber 75 and a second chamber 76 by a partition wall 74, and the fuel supply pipes 18 b and 18 c are connected to the first chamber 75, while an electromagnetic relief is provided to the second chamber 76. The fuel discharge pipes 24a and 24b having the valves 25a and 25b are connected, the fuel in the first chamber 75 is supplied to the fuel supply path 72 of the injectors 13a and 13b, and the fuel is returned from the fuel discharge path 73 to the second chamber 76. I have to. Accordingly, the fuel is supplied from the fuel discharge pipes 24a and 24 to the first chamber 75 of the delivery pipes 14a and 14b, while the fuel is discharged from the second chamber 76 by the electromagnetic relief valves 25a and 25b. A difference in fuel pressure between the second chamber 76 and the second chamber 76 can be ensured, and the fuel can be reliably circulated through the fuel passages of the injectors 13a and 14b, so that high cooling performance can be ensured.

  In addition, the end portions of the fuel introduction pipe 60 are connected to the flange portions 33 of the delivery pipes 14a and 14b via the O-rings 78 as shaft seals by the injectors 13a and 13b, and the end portions of the relief pipe 61 are connected to the partition walls 74. It is connected via an O-ring 79 as a face seal. Therefore, it is possible to ensure a high sealing performance between the inside of the delivery pipes 14a and 14b and the atmosphere, and by making one of the shaft seals and the other a face seal, the injectors 13a and 13b and the delivery pipes 14a and 14b. Even if there is a mounting error between them, good sealing performance can be ensured.

  In the above-described embodiment, the fuel passage for circulating fuel is provided in the high-pressure injector 13a and the low-pressure injector 13b. However, the low-pressure injector 13b has a tip located at the intake port 15, and deposits are deposited at a relatively low temperature. Therefore, a fuel passage for circulating fuel may be provided only in the high-pressure injector 13a.

  As described above, the fuel injection control device for an internal combustion engine according to the present invention drives the low pressure fuel injection device until the fuel pressure of the high pressure fuel injection device becomes higher than the predetermined fuel pressure at the start of driving of the high pressure fuel injection device. It is suitable for any kind of internal combustion engine.

1 is a schematic configuration diagram of a fuel injection control device for an internal combustion engine according to an embodiment of the present invention. It is a flowchart showing the fuel-injection control by the fuel-injection control apparatus of the internal combustion engine of a present Example. It is sectional drawing of the injector in the fuel-injection control apparatus of the internal combustion engine of a present Example. It is IV-IV sectional drawing of FIG. It is VV sectional drawing of FIG. It is sectional drawing of the front-end | tip part of the injector in the fuel-injection control apparatus of the internal combustion engine of a present Example. It is VII-VII sectional drawing of FIG. It is the schematic of a high pressure pump.

Explanation of symbols

10 Engine (Internal combustion engine)
11 Combustion chamber 13a High pressure injector (low pressure fuel injection device)
13b Low pressure injector (high pressure fuel injector)
14a High pressure delivery pipe 14b Low pressure delivery pipe 15 Intake port 17 Low pressure feed pump (low pressure fuel pump)
18a, 18b, 18c Fuel supply pipe 19 High pressure pump 24a, 24b Fuel discharge pipe 25a, 25b Electromagnetic relief valve (fuel circulation means)
26 Electronic control unit, ECU (control means)
32a, 32b Fuel pressure sensor 41 Holder (injection device body)
42 Valve body (Injector body)
45 Injection port (fuel injection port)
49 Needle valve (injection valve)
63 Internal passage (fuel passage)
64 External passage (fuel passage)
65 Communication hole (fuel passage)
66 Central passage (fuel passage)
68 Notch 70 Through passage (fuel passage)
72 Fuel supply passage (fuel passage)
73 Fuel discharge passage (fuel passage)
75 Room 1 76 Room 2

Claims (4)

  A low-pressure fuel injection device for injecting fuel into the intake port and a high-pressure fuel injection device for injecting fuel into the combustion chamber, wherein the control means is the low-pressure fuel injection device or the high-pressure fuel injection device according to the operating state of the internal combustion engine In the fuel injection control device for an internal combustion engine capable of selectively driving the fuel injection device, the low pressure fuel injection device and the high pressure fuel injection device include a fuel injection port provided at a distal end portion of an injection device body, and fuel to the fuel injection port. A fuel passage that can be circulated to the vicinity of the fuel passage and discharged to the outside, and an injection valve that allows the fuel passage and the fuel injection port to communicate with each other to inject a part of the fuel flowing through the fuel passage from the fuel injection port. And a fuel circulation means for forcibly circulating fuel in the fuel passage, and the control means drives the fuel circulation means when the high-pressure fuel injection device is at rest to drive the low-pressure fuel injection device and the high-pressure fuel injection device. While the fuel is circulated to the vicinity of the fuel injection port by the fuel passage in the apparatus, the driving of the fuel circulation means is stopped at the start of driving of the high pressure fuel injection apparatus, and the fuel pressure of the high pressure fuel injection apparatus is previously set. A fuel injection control device for an internal combustion engine, wherein the low pressure fuel injection device is driven until it becomes higher than a set predetermined fuel pressure.   2. The fuel injection control apparatus for an internal combustion engine according to claim 1, wherein an internal passage is formed inside the injection valve and an external passage is formed outside the injection valve by forming the injection valve in a hollow shape. And a communication hole that communicates the internal passage and the external passage is formed at a tip portion of the injection valve, and the fuel passage is configured by the internal passage, the external passage, and the communication hole. Engine fuel injection control device.   The fuel injection control device for an internal combustion engine according to claim 1 or 2, wherein the high pressure fuel injection device is connected to a fuel supply pipe having a high pressure fuel pump at one end of the high pressure delivery pipe, A fuel discharge pipe having a high-pressure relief valve is connected to the other end, and the control means reduces the set pressure of the high-pressure relief valve as the fuel circulation means when the high-pressure fuel injection device is stopped, A fuel injection control device for an internal combustion engine, wherein the fuel supplied from the fuel supply pipe to the high-pressure delivery pipe is circulated through the fuel passage and then discharged to the fuel discharge pipe through the high-pressure delivery pipe. 4. The fuel injection control device for an internal combustion engine according to claim 3, wherein a fuel supply pipe having a low pressure fuel pump is connected to one end portion of the low pressure delivery pipe, while the other end of the low pressure delivery pipe is connected to the low pressure fuel injection device. A fuel discharge pipe having a low-pressure relief valve is connected to the section, and the control means stops the high-pressure fuel pump and lowers the set pressure of the high-pressure relief valve when the high-pressure fuel injection device is stopped. A fuel injection control device for an internal combustion engine, characterized in that fuel pressurized by a low-pressure fuel pump is circulated through the fuel passage in the high-pressure fuel injection device.

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