JP3617310B2 - Fuel injection control device for internal combustion engine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fuel injection control device for an internal combustion engine that sets a fuel injection amount based on an operating state of the internal combustion engine and injects fuel from a fuel injection valve at a predetermined injection timing.
[0002]
[Prior art]
FIG. 8 is a schematic view of a fuel system applied to a general in-cylinder injection spark ignition type internal combustion engine, FIG. 9 is a cross-sectional view showing an injector mounting structure, and FIG. 10 is a conventional injector drive pulse and needle valve by fuel injection control. The graph showing the relationship between the lift position of this and the drive noise of an injector is shown.
[0003]
As shown in FIG. 8, reference numeral 101 denotes a fuel tank, which has a fuel filter 102 and a low-pressure fuel pump 103. A high pressure fuel pump 107 is connected to a feed path 104 a of a fuel passage 104 connected from the low pressure fuel pump 103 via a check valve 105 and a fuel filter 106. A delivery pipe 108 is connected downstream of the high-pressure fuel pump 107, and a plurality of injectors 110 for injecting fuel into each combustion chamber of the engine 109 are attached to the delivery pipe 108. A check valve 112 is mounted in a bypass passage 111 that bypasses the high-pressure fuel pump 107. Further, a high pressure control valve 113 is connected to the downstream side of the delivery pipe 108, and is connected to the fuel tank 101 by a return path 104 b of the fuel path 104. A low-pressure control valve 115 is mounted on the communication path 114 provided between the upstream side of the high-pressure fuel pump 107 and the most downstream side of the return path 104b in the supply path 104a of the fuel path 104.
[0004]
Accordingly, in such a fuel system, the low-pressure fuel pump 103 of the fuel tank 101 sends fuel that has been pressurized to some extent to the supply passage 104a of the fuel passage 104, and this low-pressure fuel is further pressurized by the high-pressure fuel pump 107. Thus, the fuel pressure can be increased to a predetermined pressure. At this time, the discharge pressure from the low pressure fuel pump 103 is stabilized within a predetermined range by the low pressure control valve 115, and the discharge pressure from the high pressure fuel pump 107 is stabilized within the predetermined range by the high pressure control valve 113. Then, a predetermined amount of fuel is injected from each injector 110 of the delivery pipe 108 into each combustion chamber of the engine 109.
[0005]
In such a fuel system, as described above, the injector 110 injects fuel that has been raised to a predetermined pressure by the high-pressure fuel pump 107, and the injection reaction force acts. It is necessary to attach firmly to the delivery pipe 108. That is, as shown in FIG. 9, a combustion chamber 123 is configured by fixing a cylinder head 122 on the cylinder block 121, and an intake port 124 and an exhaust port (not shown) communicate with the combustion chamber 123. The intake valve 125 and the exhaust valve (not shown) can be freely opened and closed. Further, the cylinder head 122 is fitted with the above-described injector 110 for injecting fuel into the combustion chamber 123 with its tip end facing the combustion chamber 123, and the base end portion of the injector 110 is fixed to the engine body. The delivery pipe 108 is press-fitted and attached to the attachment hole 108 a of the delivery pipe 108 via the seal member 126.
[0006]
In the injector 110, a through hole 131 communicating with the feeding path 104 a of the delivery pipe 108 is formed inside, and a rod 133 having a needle valve 132 attached to the tip is movably mounted in the through hole 131. The needle valve 132 closes the injection port 135 by the urging force of the spring 134. On the other hand, a coil 136 is provided in the periphery of the rod 133, and a voltage is applied by energizing the coil 136, and the needle valve 132 can be moved together with the rod 133 to open the injection port 135.
[0007]
Therefore, as described above, the high-pressure fuel is supplied to the supply path 104a of the delivery pipe 108, and this high-pressure fuel is supplied from the mounting hole 108a to the through hole 131 of the injector 110. In this injector 110, when the injection port 135 is opened by energizing the coil 136 and moving the needle valve 132 together with the rod 133, high-pressure fuel can be injected from the injection port 135 into the combustion chamber 123. it can.
[0008]
[Problems to be solved by the invention]
At the time of fuel injection by the injector 110 configured in this way, the needle valve 132 has a tip seated on the valve seat 137 and the injection port 135 is fully closed, and a rear end flange portion 133a is seated on the stopper 138 for injection. A stroke is made between the position where the mouth 135 is fully opened. Therefore, as can be seen from the graph shown in FIG. 10, when the fuel is injected by reciprocating the needle valve 132, the rear end flange portion 133 a abuts against the stopper 138 when the injection port 135 is opened, and a seating sound is generated. At the same time, when the injection port 135 is closed, the tip of the needle valve 132 abuts against the valve seat 137 to generate a seating sound.
[0009]
In this in-cylinder injection spark ignition type internal combustion engine, fuel injection is performed during the compression stroke in order to achieve lean operation by stratified super-lean combustion during idle operation or low speed operation to improve fuel efficiency. Therefore, the fuel pressure is increased as compared with the conventional intake port injection engine, the energy required to operate the needle valve 132 is large, and the tip of the injector body is inserted into the combustion chamber 123. The injector 110 is firmly fixed to the cylinder head 122 so that the combustion pressure does not leak. As a result, the seating vibration of the needle valve 132 is directly transmitted to the cylinder head 122, so that the seating sound of the needle valve 132 is easily heard, and the driver feels uncomfortable. For this reason, conventionally, the seating sound is prevented from leaking by attaching a cover to the injector 110 or attaching a sound insulating material to the engine room, but there is a problem that the weight increases and the cost increases. . In addition, it is conceivable to elastically support the injector 110 in the mounting hole 108a of the delivery pipe 108. However, as described above, the injector 110 is required to be firmly attached to the injector 110 due to the reaction force of the high-pressure fuel and the fuel pressure. Yes, elastic support is difficult.
[0010]
An object of the present invention is to provide a fuel injection control device for an internal combustion engine that suppresses the occurrence of a seating noise of a needle valve without causing an increase in weight or cost. .
[0011]
[Means for Solving the Problems]
In order to achieve the above object, a fuel injection control device for an internal combustion engine according to claim 1 sets a fuel injection amount based on an operating state of the internal combustion engine, and sets a needle valve of the fuel injection valve at a predetermined injection timing. In a fuel injection control device of an internal combustion engine that injects the fuel injection amount by moving and opening the injection port, a drive pulse width for opening the fuel injection port of the fuel injection valve is set. The pulse width is such that the needle valve does not move to the fully open position of the injection port. By performing the control, the needle valve is returned to the closing direction before the fully open position of the injection port during fuel injection.
[0012]
Therefore, when the fuel injection amount is set based on the operating state of the internal combustion engine, at the injection timing, the needle valve moves to open the injection port and start fuel injection. The pulse width is such that the needle valve does not move to the fully open position of the injection port. By controlling, the needle valve returns in the closing direction before the fully open position of the injection port, and the needle valve can suppress the occurrence of seating noise on the stopper in the fully open position, and can prevent the generation of noise.
[0013]
In the fuel injection control device for an internal combustion engine according to the second aspect of the present invention, the needle valve But If the injection of the set fuel injection amount is not completed before reaching the fully closed position of the injection port, the needle valve is urged in the opening direction before the fully closed position of the injection port. As described above, the interval between the drive pulses is set to an interval at which the needle valve does not move to the fully closed position of the injection port. It is characterized by this.
In the internal combustion engine fuel injection control apparatus according to the third aspect of the invention, the drive pulse width is , By the number of fuel injection divisions, the driving pulse width is such that the needle valve does not move to the fully open position of the injection port, The needle valve is returned in the closing direction just before the fully opened position of the injection port when the fuel is injected by dividing the fuel injection port into a plurality of times.
[0014]
Therefore, when the injection of the set fuel injection amount is not completed by one reciprocating movement of the needle valve at a predetermined injection timing, the needle valve is reciprocated a plurality of times to perform the fuel injection in a plurality of times. Thus, a predetermined amount of fuel can be injected. In this case, when fuel is injected and the needle valve returns to the fully closed position of the injection port, the needle valve returns to the opening direction of the injection port before the fully closed position, and the valve seat in the fully closed position is opened. Generation of seating noise can be suppressed.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0016]
FIG. 1 shows a schematic configuration of a cylinder injection spark ignition type internal combustion engine to which a fuel injection control device for an internal combustion engine according to an embodiment of the present invention is applied. FIG. 2 shows a cross section of an injector. FIG. FIG. 4 is a graph showing the relationship between the lift position of the valve and the drive noise of the injector, FIG. 4 is a graph showing the fuel injection amount with respect to the drive pulse width of the injector, and FIG. 5 is a graph showing the drive noise of the injector with respect to different drive pulse widths of the injector. FIG. 6 is a graph showing current and voltage for different drive pulse widths of the injector, and FIG. 7 is a control flowchart of the fuel injection control device for the internal combustion engine of the present embodiment.
[0017]
In the fuel injection control device for an internal combustion engine of the present embodiment, as shown in FIG. 1, the engine 10 is an in-cylinder in-line four-cylinder gasoline engine that directly injects fuel into a combustion chamber. A spark plug 12 is attached to each cylinder, and an electromagnetic injector (fuel injection valve) 13 is attached. An injection port of the injector 13 is opened in the combustion chamber 14, and fuel injected from the injector 13 through the driver 15 is directly injected into the combustion chamber 14. A piston 17 is supported on the cylinder 16 of the in-cylinder injection engine 10 so as to be slidable in the vertical direction, and a cavity 18 that is hemispherically recessed is formed on the top surface of the piston 17. A reverse tumble flow opposite to the tumble flow can be generated.
[0018]
An intake port 19 and an exhaust port 20 facing the combustion chamber 14 are formed in the cylinder head 11. The intake port 19 is opened and closed by driving an intake valve 21, and the exhaust port 20 is opened and closed by driving an exhaust valve 22. An intake side camshaft 23 and an exhaust side camshaft 24 are rotatably supported on an upper portion of the cylinder head 11. The intake valve 21 is driven by the rotation of the intake side camshaft 23. The exhaust valve 22 is driven by the rotation.
[0019]
A water temperature sensor 25 that detects the cooling water temperature is provided in the vicinity of the cylinder 16 of the in-cylinder injection engine 10. Further, a vane type crank angle sensor 26 that outputs a crank angle signal SGT at a predetermined crank position (for example, 75 degrees BTDC and 5 degrees BTDC) of each cylinder is provided, and the crank angle sensor 26 can detect the engine rotation speed. Yes. The camshafts 23 and 24 that rotate at half the number of revolutions of the crankshaft are provided with an identification sensor 27 that outputs a cylinder identification signal SGC, and the cylinder identification signal SGC can identify which cylinder the crank angle signal SGT belongs to. It is said that.
[0020]
An intake pipe 29 is connected to the intake port 19 via an intake manifold 28, and an air cleaner 30 is attached to an air intake port of the intake pipe 29. The intake pipe 29 is provided with a throttle body 31. The throttle body 31 is provided with a butterfly throttle valve 32 for opening and closing the flow path, and a throttle position sensor 33 for detecting the opening of the throttle valve 32 is attached. It has been. The throttle position sensor 30 outputs a throttle voltage corresponding to the opening degree of the throttle valve 32, and the opening degree of the throttle valve 32 is recognized based on the throttle voltage. The throttle body 31 is provided with an idle switch 34 that detects the fully closed state of the throttle valve 32 and recognizes the idling state of the in-cylinder injection engine 10. Further, an air flow sensor 35 for detecting the intake air amount and an intake air temperature sensor 36 for detecting the intake air temperature are attached to the intake pipe 29, and the Karman vortex type flow sensor is used as the air flow sensor 35.
[0021]
On the other hand, an exhaust pipe 38 is connected to the exhaust port 20 via an exhaust manifold 37. ₂ A sensor 39 is attached. The exhaust pipe 38 is provided with a three-way catalyst 40 and a muffler (not shown).
[0022]
The fuel stored in the fuel tank 41 is sucked up by the electric low-pressure fuel pump 42 and fed to the in-cylinder injection engine 10 side through the low-pressure feed pipe 43. The fuel pressure in the low pressure feed pipe 43 is regulated to a relatively low pressure (low fuel pressure) by a first fuel pressure regulator 45 provided in the return pipe 44. The fuel supplied to the in-cylinder injection engine 10 side is supplied to each injector 13 by a high-pressure fuel pump 46 via a high-pressure feed pipe 47 and a delivery pipe 48. The fuel pressure in the delivery pipe 48 is adjusted to a relatively high pressure (high fuel pressure) by the second fuel pressure regulator 50 provided in the return pipe 49. An electromagnetic fuel pressure switching valve 51 is attached to the second fuel pressure regulator 50, and the fuel pressure switching valve 51 can release the fuel in the ON state to reduce the fuel pressure in the delivery pipe 48 to a low fuel pressure. Reference numeral 52 denotes a return pipe that returns a part of the fuel used for lubrication or cooling of the high-pressure fuel pump 46 to the fuel tank 41.
[0023]
The vehicle is provided with an electronic control unit (ECU) 53 as a control device. The ECU 53 includes an input / output device, a storage device for storing a control program and a control map, a central processing unit, timers and counters. The ECU 53 performs comprehensive control of the in-cylinder injection engine 10. The detection information of the various sensors described above is input to the ECU 53, and the ECU 53 determines the ignition timing and the like starting from the fuel injection mode and the fuel injection amount based on the detection information of the various sensors. The plug 12 and the like are driven and controlled.
[0024]
In addition to the various sensors described above, a large number of switches (not shown) and the like are connected to the input side of the ECU 53, and various warning means and devices (not shown) are also connected to the output side.
[0025]
Here, the injector 13 described above will be described in detail. As shown in FIG. 2, the base portion of the housing 61 of the injector 13 is attached to the attachment hole 48 a of the delivery pipe 48 via an O-ring 62. A core 63 and a body 64 are fixed in the housing 61, and a through hole 65 is formed through the core 63 and the body 64. The through hole 65 communicates with a fuel supply hole 48b of the delivery pipe 48. . A rod 67 having a needle valve 66 attached to the tip is mounted in the through-hole 65 so as to be movable up and down, and is biased and supported downward by a biasing force of a spring 68. A valve seat 70 is fixed to the lower end portion of the body 64 via an adapter 69, and a fuel injection port 71 is formed in the valve seat 70. In addition, an armature 72 is fixed to the rod 67, and a coil 73 is attached to an upper peripheral portion of the armature 72. Further, a flange portion 74 is fixed to the upper end portion of the needle valve 66, and a stopper 75 with which the flange portion 74 abuts is fixed to the housing 61.
[0026]
Accordingly, the needle valve 66 normally has its tip seated on the valve seat 70 by the urging force of the spring 68 and closes the fuel injection port 71. When the coil 73 is energized and applied with a voltage, the needle valve 66 passes through the armature 72. The needle valve 66 moves upward together with the rod 67, and the fuel injection port 71 can be opened. At this time, when high-pressure fuel is supplied to the supply path 48b of the delivery pipe 48, the high-pressure fuel is injected from the injection hole 71 into the combustion chamber 14 through the through hole 65 from the attachment hole 48a.
[0027]
In the in-cylinder injection engine 10 configured as described above, as shown in FIG. 1, when the engine 10 is started by putting an ignition key switch (not shown) in the starter on position, the low pressure fuel pump 42 and the engine 10 are started. The high pressure fuel pump 46 is activated. Then, the low-pressure fuel pump 42 immediately becomes an output pressure state of a predetermined pressure (several atmospheres) after starting, and the high-pressure fuel pump 46 also gradually increases in fuel pressure and the discharge pressure rises to a sufficient level, resulting in high fuel injection. Pressure is obtained. The high-pressure fuel is supplied to each injector 13 by the high-pressure fuel pump 46 via the high-pressure feed pipe 47 and the delivery pipe 48, and the driver 15 drives and controls the injector 13 according to a command from the ECU 53 to open the injection port 71. Then, the high pressure fuel is directly injected into the combustion chamber 14.
[0028]
By the way, the fuel injection amount injected by the injector 13 includes the cooling water temperature from the water temperature sensor 25, the throttle opening from the throttle position sensor 30, the intake air amount from the air flow sensor 35, the intake air temperature from the intake air temperature sensor 36, O ₂ Based on the oxygen concentration in the exhaust gas from the sensor 39 and the like, the ECU 53 determines the air / fuel ratio that is set in accordance with the engine characteristics. This fuel injection amount is determined by the time during which the needle valve 66 moves to open the fuel injection port 71, and the ECU 53 applies to the coil 73 corresponding to the opening time of the fuel injection port 71 according to the fuel injection amount. Is sent to the driver 15 as a drive pulse having a predetermined width, and the driver 15 drives the needle valve 66 in accordance with the drive pulse.
[0029]
Conventionally, the ECU 53 sends one drive pulse for one fuel injection, and the needle valve 66 moves and opens the fuel injection port 71 for a time corresponding to the pulse width of the drive pulse to open a predetermined fuel. The amount was jetted. Therefore, as shown in FIG. 2, at the position where the needle valve 66 fully opens the injection port 71, the flange portion 74 comes into contact with the stopper 75, so that a seating sound is generated. Thereafter, the needle valve 66 opens the injection port 71. A seating sound was generated because the tip portion abuts against the valve seat 70 in the fully closed position.
[0030]
Therefore, in this embodiment, when the needle valve 66 moves and the fuel injection port 71 is opened during fuel injection by the injector 13, the needle valve 66 is returned in the closing direction before the fully open position of the fuel injection port 71. I am doing so. Therefore, since the needle valve 66 does not move to the fully open position of the fuel injection port 71, the flange portion 74 does not contact the stopper 75, and the seating sound of the needle valve 66 is eliminated. When a predetermined amount of fuel cannot be injected by a single fuel injection, the predetermined amount of fuel may be injected by reciprocating the needle valve 66 a plurality of times and performing fuel injection in a plurality of times.
[0031]
Hereinafter, the control of the injector 13 described above will be specifically described. As shown in FIG. 3, when the valve opening time (drive pulse width) of the fuel injection port 71 corresponding to the fuel injection amount set by the ECU 53 is T, here, the valve opening time T is divided into three times. Yes. That is, the valve opening time T / 3 is divided into three times, the needle valve 66 is moved to open and close the fuel injection port 71, and a predetermined amount of fuel is injected by performing fuel injection three times. At this time, as described above, the needle valve 66 is returned halfway without moving to the fully open position (full lift position) of the fuel injection port 71. Therefore, the drive noise when the fuel injection port 71 is opened, that is, the seating noise is eliminated because the needle valve 66 does not contact the stopper 75 with the flange portion 74.
[0032]
In this injector 13, as shown in FIG. 4, the fuel injection amount also increases proportionally with the increase in the drive pulse width (valve opening time T). In this embodiment, in the extremely low flow rate region (for example, , Driving pulse width 0.25 ms).
[0033]
Further, since it is necessary to inject a predetermined amount of fuel at a predetermined injection timing, as described above, the needle valve 66 is reciprocated a plurality of times to perform fuel injection in a plurality of times. In this case, when the needle valve 66 returns to the closing side of the fuel injection port 71 after the fuel injection port 71 is opened and fuel is injected, the needle valve 66 is moved in the opening direction of the fuel injection port 71 before the fully closed position. It is desirable to return it. Then, since the needle valve 66 does not move to the fully closed position of the fuel injection port 71, the tip end portion does not contact the valve seat 70 and the seating sound of the needle valve 66 is eliminated.
[0034]
In this case, if the valve opening time T of the fuel injection port 71 corresponding to the fuel injection amount is divided into three times, the injection interval (time) at each valve opening is important. As shown in FIG. 5 (a), when a predetermined amount of fuel is injected for a single valve opening time T of the fuel injection port 71 as in the prior art, noise is generated when the needle valve 66 is opened and closed. It has occurred. On the other hand, as shown in FIG. 5 (b), when a predetermined amount of fuel is injected at three valve opening times T / 3 = 0.25 ms of the fuel injection port 71 and each injection interval is 0.5 ms, Noise is eliminated when the needle valve 66 is opened, but noise is generated when the needle valve 66 is closed. Then, as shown in FIG. 5 (c), when a predetermined amount of fuel is injected at three valve opening times T / 3 = 0.25 ms of the fuel injection port 71 and each injection interval is 0.2 ms, Noise is eliminated when the needle valve 66 is opened and closed.
[0035]
That is, when the valve opening time (drive pulse width) of the fuel injection port 71 is 0.25 ms and the injection interval is 0.2 ms and the ECU 53 outputs a drive signal, the needle valve 66 is in front of the fully open position of the fuel injection port 71 and all the points. The fuel injection port 71 is opened and closed to perform fuel injection while reciprocating a plurality of times in front of the closed position, so that the seating noise is eliminated when the needle valve 66 is opened and closed, thereby suppressing noise. The
[0036]
The time (drive pulse width) for actually moving the needle valve 66 to open the fuel injection port 71 is the energization time to the coil 73 of the injector 13 and, as shown in FIG. When the entire amount of fuel is injected in one valve opening time T, the voltage drops simultaneously with the start of energization, the needle valve 66 opens the fuel injection port 71 and fuel injection is started, and the current value gradually decreases from the peak time. When it descends and stops, the voltage rises, the needle valve 66 closes the fuel injection port 71, and fuel injection ends. On the other hand, as shown in FIG. 6B, when the fuel injection port 71 has a valve opening time of 0.25 ms and fuel is injected at an injection interval of 0.5 ms, a current waveform similar to the conventional one is obtained, but the second and third The current peak value at the second time is low, and as shown in FIG. 6C, when the fuel is injected at an injection interval of 0.2 ms, the current peak values at the second time and the third time are further reduced.
[0037]
Here, how to divide and inject the predetermined fuel injection amount, that is, control for setting the drive pulse width as the valve opening time corresponding to one injection time will be described based on the flowchart of FIG. To do. First, in step S1, it is determined whether the normal fuel injection mode or the continuous injection mode in which a large amount of a large amount of fuel is required and the injection valve needs to be continuously opened at the time of starting or fully opening. In the continuous injection mode, the injection time is calculated in step S2, and fuel injection is executed in step S3. On the other hand, if the normal mode is determined in step S1, the drive pulse width T corresponding to a predetermined fuel injection amount is set in step S4 in order to set a drive pulse width in which the needle valve 66 of the injector 13 does not move to the fully open position. Driving pulse width T that the needle valve 66 does not move to the fully open position _MAX It is determined whether or not: Where T ≦ T _MAX If so, one full injection is performed in step S5, the injection end timing is set in step S6, and then fuel injection is performed in step S3.
[0038]
In step S4, T ≦ T _MAX Otherwise, go to step S7 and T ≦ 2T _MAX It is determined whether or not the two-part divided injection is possible. If possible, the drive pulse width is set to (T / 2) + K in step S8. _TD After the injection end timing is set in step S9, fuel injection is executed in step S3. K _TD Is a drive dead time correction value of the injector 13. In step S7, T ≦ 2T _MAX Otherwise, go to step S10 and T ≦ 3T _MAX Is determined to determine whether or not three-part divided injection is possible. If possible, the drive pulse width is set to (T / 3) + K in step S11. _TD The fuel injection is executed in step S3 after setting the injection end timing in step S12. Further, in step S10, T ≦ 3T _MAX Otherwise, the process proceeds to step S13 and T ≦ 4T _MAX By determining whether or not the four-part divided injection is possible, the same processing as described above is performed, and the number of divisions is increased and processed.
[0039]
In the above-described embodiment, the contact between the flange portion 74 and the stopper 75 is prevented at the fully opened position of the needle valve 66, and the tip of the needle valve 66 and the valve seat 70 are at the fully closed position of the needle valve 66. By preventing the contact, the occurrence of seating noise when the needle valve 66 is opened and closed is prevented, but a control signal for returning the fuel injection port 71 in the reverse direction before the fully open position or before the fully closed position is provided. By outputting, the brake may be applied to the moving force of the needle valve 66 to absorb the contact force and suppress the occurrence of seating noise.
[0040]
The fuel injection control device for an internal combustion engine according to the present invention has been described as applied to an in-cylinder in-line four-cylinder gasoline engine. However, the present invention can also be applied to an engine that injects fuel into an intake port.
[0041]
【The invention's effect】
As described above in detail in the embodiment, according to the fuel injection control device for an internal combustion engine of the invention of claim 1, the fuel injection amount is set based on the operating state of the internal combustion engine, and the fuel injection is performed at a predetermined injection timing. By moving the needle valve of the valve and opening the injection port, fuel can be injected and the drive pulse width is The pulse width is such that the needle valve does not move to the fully open position of the injection port. By controlling, the needle valve is returned in the closing direction before the fully open position of the injection port during the fuel injection, so the needle valve moves during the fuel injection to open the injection port and inject the fuel. At this time, the needle valve returns to the closing direction just before the fully opened position of the injection port, and this needle valve suppresses the occurrence of seating noise on the stopper in the fully opened position, resulting in an increase in weight. Generation of noise of the fuel injection valve can be prevented without increasing the cost.
[0042]
As described above in detail in the embodiment, according to the fuel injection control device for an internal combustion engine of the present invention, the needle valve But If injection of the set fuel injection amount is not completed by the time when the injection port is fully closed, the needle valve is urged in the opening direction before the injection port is fully closed. , Set the drive pulse interval so that the needle valve does not move to the fully closed position of the injection port Therefore, if the injection of the set fuel injection amount is not completed by one reciprocating movement of the needle valve at a predetermined injection timing, the needle valve is reciprocated a plurality of times to perform the fuel injection in a plurality of times. Thus, a predetermined amount of fuel can be injected, and at this time, when fuel is injected and the needle valve returns to the fully closed position of the injection port, the needle valve is moved in the opening direction of the injection port before the fully closed position. As a result, the needle valve can suppress the occurrence of seating noise on the valve seat in the fully closed position.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of a direct injection spark ignition type internal combustion engine to which a fuel injection control device for an internal combustion engine according to an embodiment of the present invention is applied.
FIG. 2 is a cross-sectional view of an injector.
FIG. 3 is a graph showing a relationship among injector drive pulses, needle valve lift positions, and injector drive noise;
FIG. 4 is a graph showing the fuel injection amount with respect to the drive pulse width of the injector.
FIG. 5 is a graph showing injector drive noise for different drive pulse widths of the injector.
FIG. 6 is a graph showing current and voltage for different drive pulse widths of the injector.
FIG. 7 is a flowchart of control of a fuel injection control device for an internal combustion engine according to the present embodiment.
FIG. 8 is a schematic view of a fuel system applied to a general in-cylinder injection spark ignition internal combustion engine.
FIG. 9 is a cross-sectional view showing an injector mounting structure.
FIG. 10 is a graph showing the relationship among injector drive pulses, needle valve lift position, and injector drive noise by conventional fuel injection control.
[Explanation of symbols]
10 In-cylinder injection engine
13 Injector (fuel injection valve)
14 Combustion chamber
25 Water temperature sensor
26 Crank angle sensor
27 Identification sensor
33 Throttle position sensor
34 Idle switch
35 Airflow sensor
36 Intake air temperature sensor
53 Electronic Control Unit (ECU)
66 Needle valve
70 Valve seat
71 Fuel injection port
73 coil
75 stopper

Claims (3)

Fuel injection control for an internal combustion engine that sets the fuel injection amount based on the operating state of the internal combustion engine and moves the needle valve of the fuel injection valve at a predetermined injection timing to inject the fuel injection amount by opening the injection port In the device
By controlling the drive pulse for opening the fuel injection port of the fuel injection valve to a pulse width that does not move the needle valve to the fully open position of the injection port, the needle valve is placed before the fully open position of the injection port during fuel injection. A fuel injection control device for an internal combustion engine, wherein the fuel injection control device is returned to the closing direction. The fuel injection control device for an internal combustion engine according to claim 1,
When the injection of the set fuel injection amount is not completed before the needle valve reaches the fully closed position of the injection port, the needle valve is urged in the opening direction before the fully closed position of the injection port. Thus, the fuel injection control device for an internal combustion engine is characterized in that the interval between the drive pulses is set such that the needle valve does not move to the fully closed position of the injection port . The fuel injection control device for an internal combustion engine according to claim 1,
The drive pulse width is divided into a plurality of times according to the number of divisions of fuel injection, which is a drive pulse width that does not move the needle valve to the fully open position of the injection port, and the fuel injection port is opened, thereby the needle at the time of fuel injection A fuel injection control device for an internal combustion engine, wherein the valve is returned to the closing direction before the fully open position of the injection port.

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