INJECTOR CONTROL DEVICE

Abstract

Injector control device for controlling an injector, wherein the control device comprises a control unit that controls the injector to perform a first fuel injection to inject fuel at a first fuel pressure from the injector in an intake stroke in a combustion cycle of an internal combustion engine and a second fuel injection to inject fuel at a second fuel pressure that is higher than the first fuel pressure from the injector after the first fuel injection in the same combustion cycle in the intake stroke.

Description

Technical area

[0001] The present invention relates to an injector control device. State of the art

[0002] In recent years, efforts to prevent global warming and the depletion of resources such as fossil fuels have led to calls for improved fuel efficiency and reduced carbon dioxide (CO2) emissions from internal combustion engines in vehicles. Reducing carbon dioxide emissions from internal combustion engines requires lower fuel consumption. In this respect, lean combustion is an effective technique, in which fuel is burned in a lean air-fuel mixture. Because this lean combustion requires igniting the air-fuel mixture with a low equivalent ratio (a value indicating the fuel concentration) in a cylinder, combustion slows down and tends to become unstable.Accordingly, in this type of internal combustion engine of a mobile object, a method for stabilizing combustion in the lean combustion state is available (sometimes called lean stratified combustion) in which a small amount of fuel is injected during a period of one compression stroke in a combustion cycle and the atmosphere near the spark plug is adjusted to a slightly high fuel concentration state (hereinafter sometimes referred to as the fuel-rich state).

[0003] Furthermore, due to the tightening of exhaust emission regulations, it is necessary to reduce the total amount of unburned particles (particle mass: PM) and the number of unburned particles (particle number: PN), hydrocarbons (HC) and nitrogen oxides (NOx) in the combustion engine of a mobile object.

[0004] PN and KW are generated when the fuel injected by the internal combustion engine's injector adheres to the piston and bore wall surfaces in the cylinder. Furthermore, there is a tendency for PN to increase when the air-fuel ratio (the ratio of air to fuel in the air-fuel mixture in the cylinder) is high, i.e., when there is a rich fuel mixture.

[0005] Therefore, in an internal combustion engine, to suppress the generation of PN and KW, it is necessary to reduce the amount of fuel adhering to the piston and bore wall surfaces in the cylinder.

[0006] Furthermore, a large amount of power (KW) is emitted at the moment of starting the internal combustion engine if a catalyst on the exhaust side of the engine is not activated. Accordingly, exhaust losses in the internal combustion engine can be increased, and the exhaust gas temperature can be raised, by retarding the ignition timing more after warm-up than at idle, and by suppressing power (KW) emissions by raising the catalyst temperature earlier. In the ignition timing retardation method, the compression stroke ends in a combustion cycle of the internal combustion engine, and the piston ignites during the expansion stroke from top dead center to bottom dead center. Consequently, combustion tends to become unstable.Accordingly, the method of retarding the ignition timing to ensure reliable fuel ignition requires a technique that creates a fuel-rich air-fuel mixture around the spark plug provided in the internal combustion engine, as necessary for ignition. To create a fuel-rich air-fuel mixture around the spark plug at the ignition point, this mixture can be gathered by creating a cavity (a recess) in the piston crown surface and forcing the gas mixture supplied to this cavity towards the spark plug by injecting fuel during the compression stroke.

[0007] In order to inject fuel into the cavity formed in the crown surface of the piston and to blow a fuel-rich air-fuel mixture around the spark plug, it is necessary in this case to increase the penetration of fuel injected from the injector (range of the fuel spray mist) (increase in penetration force) in order to increase the amount of air-fuel mixture blown up from the cavity so that the air-fuel mixture reliably reaches the spark plug.

[0008] On the other hand, during the intake stroke of an internal combustion engine's combustion cycle, increasing the injection duration of the fuel injected by the injector is necessary to promote the mixing of air and fuel. There are different requirements for injector injection during the intake stroke and the compression stroke.

[0009] Patent reference 1 discloses a method for changing the injection state of fuel injected by an injector as a function of an intake stroke and a compression stroke in a combustion cycle of an internal combustion engine. In the injector control method disclosed in patent reference 1, the injection pulse of the fuel injected by the injector is lengthened during the intake stroke of a combustion cycle of the internal combustion engine, while the injection pulse of the fuel injected by the injector is shortened during the compression stroke of a combustion cycle of the internal combustion engine. This method executes this injection pattern several times to change the injection state between an intake stroke and a compression stroke. PTL 2 concerns a drive system for a fuel injection device that has a function which corrects the injection pulse width when the voltage of a high-voltage source drops. The injection pulse width is lengthened if the valve closes after the drive current switches to a holding current. However, if the valve closes before the switch to the holding current, the absolute value of the injection pulse width correction is lower than in the first case.

[0010] PTL 3 relates to a control device for regulating a fuel injection device with a valve body, a solenoid coil and a movable body for opening the valve body, which controls a drive current in such a way that it is reduced after a maximum drive current has been supplied to the solenoid coil, before the valve body begins to open. List of literature on patent literature PTL 1: JP 2015 - 183 617 A PTL 2: WO 2016 / 080 067 A1 PTL 3: WO 2018 / 037 734 A1 Summary of the invention; Technical task

[0011] In this type of internal combustion engine, however, during the catalyst warm-up phase after starting the engine, a fuel-rich air-fuel mixture is required to form the spark plug and inject fuel during the compression stroke of a combustion cycle. This mixture is essential for combustion stability. Especially when the injector is a side-injection type, mounted on a side of the combustion chamber, the distance between the injector and the spark plug is large. Therefore, to create a fuel-rich air-fuel mixture around the spark plug, the amount of fuel injected during the compression stroke must be increased at a predetermined ignition point. Conversely, during the compression stroke of a combustion cycle, the distance between the injector and the piston crown becomes short.This poses a problem, insofar as the fuel injected by the injector tends to stick to the piston, and the amounts of KW and PN produced increase.

[0012] Furthermore, during the intake stroke of a combustion cycle, when the catalyst is warming up, there is a requirement to increase the injection duration of the fuel injected by the injector to improve air-fuel homogeneity. On the other hand, the temperature of a cylinder wall surface is low after starting the combustion engine while the catalyst is warming up. Consequently, in some cases, the fuel injected during the intake stroke adheres to the cylinder wall surface, and the resulting amounts of crankshaft pressure (KW) and pressure (PN) increase, leading to a deterioration of air-fuel homogeneity.

[0013] Therefore, the present invention has the objective of providing an injector control device that is able to improve the homogeneity of the air-fuel mixture in the intake stroke in a combustion cycle of an internal combustion engine and to ensure combustion stability, while reducing exhaust emissions in the compression stroke. Solution to the task

[0014] To solve the task described above, a control device for controlling an injector includes a control unit that controls the injector to perform a first fuel injection to inject fuel at a first fuel pressure from the injector in an intake stroke in a combustion cycle of an internal combustion engine, and a second fuel injection to inject fuel at a second fuel pressure that is higher than the first fuel pressure from the injector after the first fuel injection in the same combustion cycle in the intake stroke. Advantageous effects of the invention

[0015] According to the present invention, combustion stability in an internal combustion engine can be improved while exhaust emissions are suppressed. Brief description of the illustrations [ Fig. 1] Fig. Figure 1 is a schematic diagram representing a fuel injection system consisting of a control device, an injector, and a pressure sensor. [ Fig. 2] Fig. Figure 2 is a cross-sectional view showing the structure of the injector and an example of the configuration of the control device for driving the injector. [ Fig. 3] Fig. Figure 3 is an enlarged view of section A of Fig. 2. [ Fig. 4] Fig. Figure 4 is a view showing the relationship between a fuel control signal output by an engine control unit (ECU), a drive voltage of the solenoid coil of an injector, a drive current and the displacement amount of a valve body over time. [ Fig. 5] Fig. Figure 5 is a view that represents the state in which fuel is injected from the injector into the cylinder of the internal combustion engine. [ Fig. 6] Fig. Figure 6 is a schematic diagram that represents the main part of the system configuration of the internal combustion engine. [ Fig. 7] Fig. Figure 7 is a view that illustrates the relationship between the crank angle, the lift amount of an inlet valve, and the turbulent velocity in the cylinder. [ Fig. 8] Fig. Figure 8 shows a projection of fuel injected by the injector, seen in the direction of the injector from a cross-section A - A of Fig. 5. [ Fig. 9] Fig. Figure 9 is a view showing the temporal changes in the pulse width of a fuel control signal, drive current, and valve body displacement amount output by the control device. [ Fig. 10] Fig. Figure 10 is a view that shows the state of the fuel injected by the injector in a compression stroke. [ Fig. 11] Fig. Figure 11 is a cross-sectional view showing the structure of an injector according to the second embodiment. [ Fig. 12] Fig. Figure 12 is an enlarged view of the environment of a mover mechanism, showing a state in which the mover mechanism is pushed towards the fuel injection port by a first spring. [ Fig. 13] Fig. Figure 13 is an enlarged view of the environment of the mover mechanism, showing a short stroke state in which a second mover of the mover mechanism is attracted by the magnet coil. [ Fig. 14] Fig. Figure 14 is an enlarged view of the environment of the mover mechanism, showing a long-stroke state in which the first mover and the second mover are attracted by the magnet coil. [ Fig. 15] Fig. Figure 15 is a view that shows an example of the drive current supplied to the injector's solenoid coil. [ Fig. 16] Fig. Figure 16 is a view that illustrates an example of the relationship between a fuel control signal and a fuel injection quantity. [ Fig. 17] Fig. Figure 17 is a view showing the temporal relationship between a fuel control signal, a drive current and the displacement amount of a valve body according to the second embodiment. Description of the embodiments

[0016] Embodiments of the present invention are described in detail below with reference to the accompanying drawings. [First embodiment]

[0017] First, an injector control device (hereinafter referred to as control device 1) according to the first embodiment of the present invention is described. This embodiment presents, by way of example, a case in which the control device 1 is applied to the control of the injectors 103 to 106 provided in the inline four-cylinder piston internal combustion engine for a vehicle.

[0018] Fig. Figure 1 is a schematic diagram representing a fuel injection system 4 consisting of the control device 1, the injectors 103 to 106 and a pressure sensor 3.

[0019] As in Fig. As shown in Figure 1, in the inline four-cylinder piston internal combustion engine (hereinafter referred to as internal combustion engine 100), four cylinders (hereinafter referred to as cylinders 102) are arranged in a row in a cylinder block 101. In this embodiment, the cylinders 102 comprise a first cylinder 1021, a second cylinder 1022, a third cylinder 1023, and a fourth cylinder 1024, arranged in the direction shown from the left side of Fig. The cylinders are arranged in the sequence mentioned in Section 1, and cylinders 1021 to 1024 are each equipped with injectors 103, 104, 105 and 106 (also referred to as fuel injection devices). The fuel injection ports 1031 to 1061, provided at the respective distal ends of the injectors 103 to 106, are located in the combustion chambers 1021a to 1024a of the respective cylinders 1021 to 1024, and the fuel injected from the fuel injection ports 1031 to 1061 of the injectors 103 to 106 is injected directly into the combustion chambers 1021a to 1024a. The fuel is supplied by a fuel pump 107, fed to a rail line 108 (fuel line) and then supplied to each of the injectors 103 to 106.The fuel pressure (hereinafter referred to as fuel pressure) varies depending on the balance between the flow rate of the fuel delivered by the fuel pump 107 and the amount of fuel injected by the injectors 103 to 106, located in the respective cylinders 1021 to 1024, into the respective combustion chambers 1021a to 1024a. The amount of fuel delivered by the fuel pump 107 is controlled by setting a predetermined pressure as a target value based on information from a pressure sensor 109, which is provided for the rail line 108.

[0020] The pressure (fuel pressure) and the injection quantity of the fuel injected by injectors 103 to 106 are controlled by the pulse of a fuel control signal 300, which is output by a control unit 21 of an engine control unit (ECU) 2. The fuel control signal 300 output by the control unit 21 of the ECU 2 is input into a drive circuit 3, which drives the injectors 103 to 106. The drive circuit 3 generates the waveform of a drive current 400 to drive the injectors 103 to 106 based on the fuel control signal 300 output by the control unit 21 and supplies the drive current 400 to the injectors 103 to 106 for a time corresponding to the pulse width of the fuel control signal 300.This embodiment illustrates the case where the ECU 2 and the drive circuit 3 are separated into distinct components and connected to each other via a signal line Ln1 and a communication line Ln2. The drive circuit 3 can be mounted as a single component or circuit board integrated into the ECU 2.

[0021] In this embodiment, the ECU 2 and the drive circuit 3, which are provided as a single unit or separately, are together referred to as the control device 1. [Injector]

[0022] Next, the structure and basic function of injectors 103 to 106 will be described. The structure of injector 103, described above, is shown below as an example, but since the other injectors 104 to 106 have the same structure, a detailed description of them is omitted.

[0023] Fig. Figure 2 is a cross-sectional view showing the structure of the injector 103 and an example of the configuration of the control device 1 for driving the injector 103. Fig. Figure 3 is an enlarged view of section A of Fig. 2. Referring to the Fig. 2 and Fig. 3 is the top side in each drawing, defined as the upstream side in the fuel flow direction, and the bottom side is defined as the downstream side in the fuel flow direction.

[0024] As in Fig. As shown in Figure 2, the control unit 21 of the ECU 2 receives signals indicating the operating state of the internal combustion engine 100 from various types of sensors 5 and calculates the pulse width of the fuel control signal 300 to control the amount of fuel injected by the injector 103 and the injection timing according to the operating state of the internal combustion engine 100. The ECU 2 also includes an analog-to-digital converter (A / D converter) 22 for receiving signals from the various types of sensors 5 and an input / output port (I / O port) 23. The fuel control signal 300 output by the control unit 21 is fed into the drive circuit 3 via the signal line Ln1.

[0025] The drive circuit 3 generates the drive current 400 based on the fuel control signal 300 to produce a drive voltage 500, which is applied to the solenoid coil 1032 of the injector 103. The control unit 21 communicates with the drive circuit 3 via the communication line Ln2 and can change the drive current 400 and the set value of the drive time by switching the drive current 400 generated by the drive circuit 3 depending on the pressure of the fuel supplied to the injector 103 and the operating state of the internal combustion engine 100.

[0026] The injector 103 is a closed solenoid valve (electromagnetic fuel injection device) in which the fuel injection port 1031 is closed when no drive voltage 500 is applied to a solenoid 1032 (under normal conditions). That is, when no drive voltage 500 is applied to the solenoid 1032, a valve body 1033 is closed by a spring 1034 (downstream side). Fig. 2) pre-tensioned, and the valve body 1033 and a valve seat 1035 come into close contact with each other to close the valve. When the injector 103 is in the closed valve state, the pre-tension force of a return spring 1037 acts in the opening direction (upstream side in Fig. 2) on a mover 1036. Since in this case the downstream preload force of the spring 1034, which preloads the valve body 1033, is greater than the upstream preload force of the return spring 1037, an end surface 1036a of the mover 1036 comes into contact with the valve body 1033 in order to limit the movement of the mover 1036 in the direction of the X-axis (see Fig. 3) Furthermore, the valve body 1033 and the mover 1036 are configured to effect a relative displacement and are contained in a nozzle holder 1038. As in Fig. As shown in Figure 3, the nozzle holder 1038 has an end surface 1038a which serves as a spring seat for the return spring 1037. The preload force exerted by the spring 1034 on the downstream side is reduced at the time of assembly by the pressure exerted by a spring retainer 1040 (see Figure 3). Fig. 2) set, which is attached to the inner diameter side of a solid core 1039.

[0027] As in Fig. As shown in Figure 3, the solid core 1039, the mover 1036, the nozzle holder 1038, and a housing 1041 in the injector 103 form a magnetic circuit, and a gap C1 is formed between the mover 1036 and the solid core 1039. A magnetic diaphragm 1042 is formed in a section of the nozzle holder 1038, corresponding to the gap C1 between the mover 1036 and the solid core 1039. The magnetic coil 1032 is attached to the outer circumferential side of the nozzle holder 1038 and is wound around a coil former 1043. As shown in Figure 3, the magnetic coil 1032 is wound around a coil former 1043. Fig. As shown in Figure 2, a rod guide 1044 is attached to the nozzle holder 1038 near the distal end section of the valve body 1033 on the side of the valve seat 1035. The valve body 1033 is guided by the spring seat (not shown) of the valve body 1033 and a rod guide 1044 so that it is displaceable in the direction of the X-axis. An opening 1045, in which the valve seat 1035 and the fuel injection port 1031 are formed, is provided at the distal end section of the nozzle holder 1038, and an interior space (fuel channel) provided between the mover 1036 and the valve body 1033 is sealed from the outside.

[0028] The fuel supplied to injector 103 is taken from the rail line 108 (see Fig. 1) supplied to the upstream side of injector 103 in the fuel flow direction, and flows through a lower fuel channel opening 1047, which is provided in a first fuel channel opening 1046 and the mover 1036, and is sealed by a seat section 1033b and the valve seat 1035, which are formed at the end section of the valve body 1033 on the side of the valve seat 1035, to the distal end of the valve body 1033. In injector 1033, when the valve is closed, a pressure differential (differential pressure) is generated between the upper and lower sections of the valve body 1033 due to the fuel pressure, and the valve body 1033 is actuated in the valve closing direction by the pressure differential obtained by multiplying the fuel pressure by the pressure-bearing area of ​​the seat inner diameter at the valve seat position and the load of the spring 1034. pressed.When the solenoid coil 1032 is energized from the closed valve state, a magnetic field is generated in the magnetic circuit, a magnetic flux flows between the solid core 1039 and the mover 1036, and a magnetic attraction force acts on the mover 1036. At a point in time when the magnetic attraction force acting on the mover 1036 exceeds the differential pressure and the preload force of the spring 1034 on the downstream side, the mover 1036 begins to move in the direction of the solid core 1039 along the X-axis (the valve begins to open).

[0029] The mover 1036 and the solid core 1039, which have thus completed the valve closing process, remain stationary in the open position of the valve. In the open position of the injector 103 valve, there is a gap for storing fuel between the valve body 1033 and the valve seat 1035, and the fuel stored in this gap is injected into the cylinder 1021 through the fuel injection port 1031. In this case, the fuel pressure of the fuel injected by the injector 103 is determined by the fuel pressure supplied by the rail line 108, the displacement of the valve body 1033 of the injector 103 (the area of ​​the fuel channel), and the like. Assuming that the fuel pressure supplied by the rail line 108 does not fluctuate or only fluctuates slightly, the fuel pressure is determined by the displacement of the valve body 1033 of the injector 103.In particular, if the displacement of the valve body 1033 is small, the flow rate of fuel passing through the fuel injection port 1031 per unit time decreases. Consequently, if the fuel pressure of the fuel injected by injector 1033 decreases and the displacement of the valve body 1033 is large, the amount of fuel flowing through the fuel injection port 1031 increases, and as a result, the fuel pressure of the fuel injected by injector 1031 increases (see ). Fig. 9) In this case, the fuel flow rate per unit of time refers to the flow rate of the fuel injected per unit of time during the valve opening period of the valve body 1033.

[0030] This means that the fuel flow rate per unit of time represents the fuel injection rate, which is represented by the gradient in the graph, where the ordinate represents the amount of fuel injected by injector 103 and the abscissa represents time.

[0031] When the drive current 400 supplied to the solenoid coil 1032 is switched off, the magnetic flux generated in the magnetic circuit disappears, and the magnetic attraction acting on the mover 1036 also disappears. As a result, the mover 1036 and the valve body 1033 are pushed back into the valve closing position due to the load of the spring 1034 and the pressure differential, where they come into contact with the valve seat 1035 to close the valve. [Valve body actuation method]

[0032] Next, the relationship between the fuel control signal 300 output by the control unit 21 of the ECU 2 according to the embodiment of the present invention, the drive voltage 500 applied to the solenoid coil 1032 of the injector 103, the drive current 400 and the displacement amount of the valve body 1033 (the behavior of the valve body 1033) is described.

[0033] Fig. Figure 4 is a view showing the fuel control signal 300 output by the ECU 2, the drive voltage 500 applied to the solenoid coil 1032 of the injector 103, the drive current 400 and the displacement amount of the valve body 1033 (the behavior of the valve body).

[0034] The top diagram of Fig. Figure 4 is an example of the fuel control signal 300 (injection pulse) output by control unit 21 of ECU 2 to drive circuit 3. The fuel control signal 300 is an ON / OFF signal and is switched on for a predetermined time when injector 103 is actuated. The second diagram from the top of Fig. Figure 4 is an example of the waveform of the drive voltage 500 generated by the drive circuit 3, which is based on the fuel control signal 300 output by the control unit 21. The drive voltage 500 generated by the drive circuit 3 includes a high voltage 501, which is boosted to a voltage VH higher than a battery voltage VB, in order to rapidly increase the drive current 400 supplied to the solenoid coil 1032 in a short time to open the valve body 1033, and a holding voltage 502, which is configured to switch a drive voltage on and off to perform intended power control, in order to hold the valve body 1033 in the open position. The third diagram from the top of Fig. Figure 4 is an example of the waveform of the drive current 400 flowing through the solenoid 1032 due to the drive voltage 500 generated by the drive circuit 3. The drive current 400 flowing through the solenoid 1032 reaches a peak current value Ipeak when the high voltage 501 is applied and then decreases sharply when the drive voltage 500 is stopped (drive current 401). The drive current 400 is held at a substantially constant current value Ia by the holding voltage 502 of the drive voltage 500 (holding current 402). The bottom diagram of Fig. Figure 4 is an example of the displacement amounts of the valve body 1033 of the injector 103 and the mover 1036. The valve body 1033 begins to displace (open) after a slight time delay when the drive current 400 flowing through the solenoid coil 1032 increases, and is displaced to a position exceeding a maximum height position Hmax after the drive current 400 reaches its peak current value ISpeak. Subsequently, the displacement of the valve body 1033 from a position exceeding the maximum height position Hmax to a position below the maximum height position Hmax decreases in accordance with the abrupt decrease in the drive current 400, and the holding current 402 of the drive current 400 holds the valve body 1033 in a predetermined height position, which is the maximum height position Hmax. The mover 1036, on the other hand, is displaced in a manner almost identical to that of the valve body 1033.After the valve body 1033 reaches its maximum height position Hmax (time t2), the displacement temporarily decreases to a height position lower than the maximum height position Hmax. Subsequently, the displacement of the mover 1036 increases to the same maximum height position Hmax as the valve body 1033 and is then held at a predetermined height position, which is the maximum height position Hmax.

[0035] Next, the configuration of the internal combustion engine 100, which is equipped with the injector 103 according to the embodiment, and the condition of the fuel injected by the injector 103 are described. The embodiment illustrates, by way of example, an internal combustion engine with direct injection that injects fuel directly into the cylinder 1021. Fig. Figure 5 is a view showing the state in which fuel is injected from injector 103 into cylinder 1021 of internal combustion engine 100. Fig. Figure 6 is a schematic diagram that represents the main part of the system configuration of the internal combustion engine 100. Fig. Figure 7 is a diagram illustrating the relationship between the crank angle, the lift of an intake valve 114, and the turbulent velocity in cylinder 1021. Top dead center (TDC) and bottom dead center (BDC) in an intake stroke S1 correspond to -360 degrees and -180 degrees, respectively, and TDC in a compression stroke S2 ​​corresponds to 0 degrees. The lift of the intake valve 114 is indicated by the dotted line, the mean turbulent velocity in cylinder 1021 is indicated by the dashed line, and the tumble in cylinder 1021 is indicated by the solid line.

[0036] The configuration of the internal combustion engine 100 with the injector 103, a spark plug 110, an intake port 111, an exhaust port 112, a piston 113, the intake valve 114 and an exhaust valve 115 is described with reference to Fig. 5 described.

[0037] A crown surface 1131 of the piston 113, located on the spark plug 110 side, has a cavity 1132 that is designed to be lower than the upper end surface of the piston 113 on the spark plug 110 side. The cavity 1132 serves to hold the air-fuel mixture obtained by mixing the fuel injected by the injector 103 with air. The intake port 111 is provided with a fixed partition 116 that blocks the airflow from an upper section 111a to a lower section 111b of the intake port 111. Upstream of this partition 116, a valve 117 is provided, the opening and closing of which is controlled by the ECU 2.

[0038] In this embodiment, the valve 117 is shown in the closed state.

[0039] Next, the main part of the system configuration of the internal combustion engine 100 will be described with reference to Fig. Section 6 describes the configuration. The following illustrates the configuration with respect to cylinder 1021. Since the configuration is the same for each of the remaining cylinders 1022 to 1024, a detailed description is omitted.

[0040] In the internal combustion engine 100, air drawn from the outside air is supplied to the cylinder 1021 via an air filter 120, a charging chamber 122 equipped with superchargers 121, an intercooler 123, a throttle valve 124, and the intake opening 111. The air filter 120, located at the air intake opening, removes dust and dirt contained in the air and prevents dust and the like from entering the internal combustion engine 100, thereby suppressing internal wear of the internal combustion engine 100. The charging chamber 122 is equipped with superchargers 121 (turbines) on both the intake and exhaust sides, and the superchargers 121 on the intake and exhaust sides are connected to each other via a shaft 125.

[0041] Accordingly, the intake-side turbocharger 121 rotates in sync with the exhaust-side turbocharger 121, corresponding to the flow velocity of the exhaust gas flowing through the exhaust port 112. The rotation of the intake-side turbocharger 121 can increase the amount of air flowing into cylinder 1021, thus increasing the power output of the internal combustion engine 100. Furthermore, the temperature of the air flowing through the charging chamber 122 increases due to the boost provided by the turbocharger 121. After the air has been cooled by the charge air cooler 123, it flows through the throttle valve 124 into cylinder 1021 to regulate the amount of air flowing into cylinder 1021 and the intake port 111. In cylinder 1021, the air-fuel mixture obtained by mixing fuel and air is ignited by the spark plug 110, and the driving force obtained by combustion is transferred to a crankshaft 126.The exhaust valve 115 then opens during the expansion stroke to rotate the turbocharger 121 on the exhaust side at the flow rate of the exhaust gas expelled from the exhaust port 112. Subsequently, hydrocarbons (HCs), nitrogen oxides (NOx), and carbon monoxide (CO) contained in the exhaust gas are removed by being reduced and oxidized by palladium, rhodium, platinum, and the like, which form a catalyst 127, as they pass through the catalyst 127. However, if the temperature of the catalyst 127 is low, the ability of palladium or the like to reduce HCs or the like is low, so the catalyst 127 must be warmed up early, especially under conditions such as at the time of starting the internal combustion engine 100.

[0042] An example of a fuel injection control system under the warm-up conditions for the catalyst 127 is given with reference to Fig. As described in section 7, under the warm-up conditions for the catalyst 127, the opening of the intake valve 114 to draw air into the combustion chamber is initiated at time t1 when the piston 113 reaches top dead center (TDC) and immediately before or at the same time as the exhaust valve 115 opens. At time t2, when the intake valve 114 begins to open and reaches its maximum stroke volume, the injector 103 performs a fuel injection during the intake stroke S1 (first fuel injection 1001). After the piston 113 has reached bottom dead center (BDC) from TDC during the compression stroke S2, at time t3 before the piston 113 reaches TDC from BDC, a fuel injection from the injector 103 occurs during the compression stroke S2 ​​(second fuel injection 1002).

[0043] Consequently, during the compression stroke S2, as the piston 113 approaches the spark plug 110, the air-fuel mixture obtained by mixing the fuel injected by the injector 103 with air enters the cavity 1132 of the crown surface 1131 of the piston 113. The air-fuel mixture that enters the cavity 1132 during the movement of the piston 113 to top dead center (TDC) is blown upwards towards the spark plug 110. This can create a fuel-rich air-fuel mixture around the spark plug 110, which is richer in fuel than the stoichiometric air-fuel ratio (hereafter sometimes referred to as the stoichiometric ratio). The control unit 21 of the ECU 2 controls the injector 103 to inject fuel from the injector 103 at predetermined injection times t2 and t3 in the intake stroke S1 and compression stroke S2 ​​described above.At this point, the ratio (division ratio) of the fuel injected in the intake stroke S1 and the fuel injected in the compression stroke S2 ​​is adjusted so that it is greater in the intake stroke S1, and is preferably set, for example, to about 6:4, 7:3 or 8:2.

[0044] In the combustion engine 100, at a time t4, a fuel-rich air-fuel mixture is drawn around a negative electrode 110b and a positive electrode 110a (see Fig. 5) spark plug 110 is formed, ignition by spark plug 110 and the air-fuel mixture is ignited and burned. At time t4, to ensure a fuel-rich air-fuel mixture around spark plug 110, it is necessary to increase the amount of fuel injected by injector 103 during compression stroke S2. Since the distance between injector 103 and piston 113 is short during compression stroke S2, the injected fuel can adhere to piston 113, increasing the exhaust gas coolant (KW) or pressure (PN) if a large amount of fuel is injected by injector 103. Accordingly, control unit 21 controls injector 103 so that the amount of fuel injected in the second fuel injection 1002 during compression stroke S2 ​​is smaller than the amount of fuel injected in the first fuel injection 1001. This suppresses the generation of KW and PN.

[0045] The fuel injection control of injector 103 by control unit 21 of ECU 2 is carried out with reference to the Fig. 8 to 10 described. Fig. 8 is a cross-sectional view along line A - A in Fig. 5 and is a schematic view showing the state of the fuel injected by injector 103 when viewed from the direction of injector 103 from cross-section A - A. Fig. Figure 9 is a view showing the temporal changes of the pulse width of a fuel control signal 300 issued by the control device 21 according to the embodiment of the present invention, the drive current 400 and the displacement amount of the valve body 1033. Fig. Figure 10 is a view that represents the state of the fuel injected by injector 103 in a compression stroke S2.

[0046] First, as in Fig. Figure 8 shows that the injector 103 according to the embodiment is a multi-hole injector with several fuel injection openings 1031 and is designed to be able to emit, for example, spray mist in six directions, namely a spray mist D1 directed towards the spark plug 110, spray mist D2 and D6 in directions near the intake valve 114 and spray mist D3, D4 and D5 directed towards the piston 113.

[0047] During fuel injection in the compression stroke S2, the control unit 21 can create a fuel-rich air-fuel mixture around the spark plug 110 by introducing the spray mist D4 and D1 into the cavity 1132 of the piston 113. Furthermore, depending on the size of the cavity 1132 and the fuel injection timing, spray mist D2 and D6 or spray mist D3 and D5 can also be introduced into the cavity 1132. This can also create a fuel-rich air-fuel mixture around the spark plug 110.

[0048] Next, as in Fig. 9 shown, the control unit 21 directs the injector 103 to perform the injection (first fuel injection 1001) in the intake stroke S1 at least twice at a position where the displacement amount of the valve body 1033 is lower than the maximum height position Hmax. The control unit 21 then controls the injector 103 to perform the second fuel injection 1002, in which the displacement of the valve body 1033 is greater than in the first fuel injection 1001. In this case, in the control unit 21 of the embodiment, periods in which the valve body 1033 is open and fuel is injected during the first fuel injection 1001 are defined as injection periods p11, p12 and p13, and a period in which the valve body 1033 is open and fuel is injected during the second fuel injection 1002 is defined as injection period p14.In this case, the pulse width of the fuel control signal 300 (the switch-on time of the drive current 400) is set such that each of the injection periods p11, p12, and p13 is shorter than the injection period p14. In this case, the control unit 21 controls the injector 103 such that the total period (P11 + P12 + P13) of the injection periods P11, P12, and P13 during the first fuel injection 1001, which occurs in the intake stroke S1, is longer than the injection period P14 during the second fuel injection 1002, which occurs in the compression stroke S2 ​​(P11 + P12 + P13 > P14).

[0049] In the control unit 21, the fuel flow rate per unit of time in a period P15 from time t12, when the valve body 1033 for the first fuel injection 1001 begins to open the valve, i.e., the time when the fuel injection begins, until time t13, when the first fuel injection 1001 ends, is set so that it is smaller than the fuel flow rate per unit of time in the period p14 from time t14, when the valve body 1033 begins to open the valve for the second fuel injection 1002, i.e., the time when the fuel injection begins, until time t15, when the second fuel injection 1002 ends.

[0050] The control unit 21 controls the injector 103 such that the displacement of the valve body 1033 becomes less than the maximum vertical position Hmax, and performs the first fuel injection 1001 during the intake stroke S1, with the fuel pressure of the fuel injected by the injector 103 being low (the flow rate per unit time is low). This promotes the mixing of air and fuel in the cylinder 1021 and forms a homogeneous air-fuel mixture in the combustion engine 100, thereby suppressing NOx emissions. Furthermore, during the first fuel injection 1001, the pressure drop between the valve body 1033 and the seat section 1033b becomes large, since the displacement of the valve body 1033 is less than the maximum vertical position Hmax of the valve body 1033 displacement. This reduces the range (penetration) of the fuel spray mist injected from the fuel injection port 1031.As a result, it is possible to prevent the spray mist of the fuel injected by the injector 103 from adhering to the bore wall surface and the crown surface 1131 of the piston 113 and to reduce the KW.

[0051] To perform the first fuel injection 1001, in order to inject fuel while the displacement of the valve body 1033 is less than the maximum altitude position Hmax, the control unit 21 performs a control operation to reduce the pulse width of the fuel control signal 300 compared to the second fuel injection 1002 and to reduce the drive current 400 to be supplied to the solenoid coil 1032. This makes it possible to perform a control operation to decrease the magnetic attraction force acting on the valve body 1033 and thus reduce the displacement of the valve body 1033 compared to the maximum altitude position Hmax.

[0052] Fig. Figure 9 illustrates the case where the first fuel injection 1001 is performed three times in the intake stroke S1. However, the first fuel injection 1001 can be performed two or more times (for example, four or five times or more).

[0053] The control unit 21 controls the injector 103 such that the displacement of the valve body 1033 becomes equal to the maximum height position Hmax, and performs the second fuel injection 1002 during the compression stroke S2, whereby the fuel pressure of the fuel injected by the injector 103 is higher than that of the first fuel injection 1001 (the flow rate per unit time is high). This makes it possible to inject a small amount of fuel spray with a strong penetration force, i.e., high penetration from the injector 103. As a result, the air-fuel mixture can reliably reach the spark plug 110, and PN and KW can be suppressed.Furthermore, the control unit 21 controls the injector 103 to perform the second fuel injection 1002, in which the displacement of the valve body 1033 is greater than that in the first fuel injection 1001, by performing a control operation to increase the pulse width of the fuel control signal 300 for the second fuel injection 1002 and to increase the drive current 400 supplied to the solenoid coil 1032. As a result, the magnetic attraction force acting on the valve body 1033 in the injector 103 is increased, and the displacement of the valve body 1033 in the second fuel injection is increased compared to the displacement of the valve body 1033 in the first fuel injection.

[0054] In this embodiment, the control unit 21 sets the injection timing t14 of the second fuel injection 1002 in a fuel cycle of the internal combustion engine 100 to a time that is later than the injection timing t12 of the first fuel injection 1001 and, in particular, within the period of the compression stroke S2. The control unit 21 controls the injector 103 to perform the second fuel injection 1002 during the compression stroke S2, so that the fuel is injected at the time when the piston 113 moves towards top dead center (TDC), and a large quantity of injected fuel is released into the cavity 1132 formed in the crown surface 1131 of the piston 113. As a result, the fuel that has entered the cavity 1132 is blown upwards towards the spark plug 110, and a fuel-rich air-fuel mixture can be formed around the spark plug 110.The shorter the distance between injector 103 and the cavity 1132 of piston 113, the more easily the fuel injected by injector 103 enters the cavity 1132. Accordingly, for example, the control unit 21 preferentially controls injector 103 to perform the second fuel injection 1002 after 70 degrees, before the crankshaft angle reaches top dead center (TDC) (at a slow point in a fuel cycle). As in . Fig. As shown in Figure 10, the control unit 21 controls the injector 103 to perform the second fuel injection 1002 after 70 degrees, before the crankshaft angle reaches top dead center (TDC) (at a slow point in a fuel cycle). This causes many of the fuel sprays D2 to D6 injected by the injector 103 to enter the cavity 1132 of the piston 113, which is closer to the injector 103. The fuel spray entering the cavity 1132 then comes into contact with an inclined surface 1133 of the cavity 1132 and is blown upwards towards the spark plug 110, creating a fuel-rich air-fuel mixture around the spark plug 110.

[0055] Fig. Figure 9 illustrates the case where the second fuel injection 1002 is performed once during the compression stroke S2 ​​according to the embodiment. However, the second fuel injection 1002, which is performed during the compression stroke S2, can be performed in two or more stages. It is assumed that the second fuel injection 1002 is performed in two stages. In this case, after the formation of an air-fuel mixture in the cavity 1132 during the first injection, the velocity of the spray D6 near the cavity 1132 decreases during the second injection, while the velocity of the spray D1 located far from the cavity 1132, i.e., the wall surface, does not decrease. This creates a vertical differential pressure in the cylinder 1021 and can intensify the effect of blowing the air-fuel mixture formed in the cavity 1132 upwards towards the spark plug 110.

[0056] As described above, according to the first embodiment (1), the control device 1 for controlling the injector 103 includes the control unit 21, which controls the injector 103 to perform the first fuel injection 1001 to inject fuel at the first fuel pressure from the injector 103 in the intake stroke S1 in a combustion cycle of the internal combustion engine 100, and to perform the second fuel injection 1002 to inject fuel at the second fuel pressure, which is higher than the first fuel pressure, from the injector 103 after the first fuel injection 1001 in the same combustion cycle in the intake stroke S1.

[0057] With this configuration, the control unit 21 performs spraying at a low fuel pressure during the first fuel injection 1001. This can improve the homogeneity of the air-fuel mixture in the combustion chamber, reduce the adhesion of the spray mist of the fuel injected by the injector 103 to the bore wall surface and the crown surface 1131 of the piston 113, and reduce the generation of PN and KW. Furthermore, since the control unit 21 performs spraying at a high fuel pressure during the second fuel injection 1002 after the first fuel injection 1001, the spray mist easily reaches the vicinity of the spark plug 110 and can form a fuel-rich air-fuel mixture near the spark plug 110. Therefore, combustion stability can be improved.

[0058] (2) In addition, the control unit 21 is configured to control the injector 103 such that the second fuel injection 1002 takes place in the compression stroke S2 ​​in the same combustion cycle as the intake stroke S1 in which the first fuel injection 1001 takes place.

[0059] In this configuration, the spray generated by the second fuel injection 1002 is blown upwards by the piston 113, which has moved to top dead center (TDC) during the compression stroke S2 ​​following the intake stroke S1, towards the vicinity of the spark plug 110. This creates a fuel-rich air-fuel mixture near the spark plug 110. Therefore, the spark plug 110 can be easily ignited, and combustion stability is improved.

[0060] (3) The control unit 21 is configured to control the injector 103 such that the displacement amount of the mover 1036 of the injector 103 during the first fuel injection 1001 is smaller than the displacement amount of the mover 1036 of the injector 103 during the second fuel injection 1002.

[0061] With this configuration, the control unit 21 can reduce the fuel pressure of the fuel injected by injector 103 during the first fuel injection 1001 compared to the fuel pressure of the fuel injected by injector 103 when the valve body 1033 of injector 103 is in its maximum height position Hmax. This can improve the homogeneity of the air-fuel mixture in cylinder 1021, reduce fuel adhesion to the bore wall surface and piston 113, and decrease the generation of PN and KW.

[0062] (4) As described above, the control unit 21 is configured to control the injector 103 so that the penetration (range of the spray mist) of the fuel sprayed during the second fuel injection 1002 extends further than the penetration (range of the spray mist) of the fuel sprayed during the first fuel injection 1001.

[0063] With this configuration, the control unit 21 controls the injector 103 to reduce the penetration of the fuel injected during the first fuel injection 1001 in the intake stroke S1. This reduces the fuel spray pattern injected by the injector 103 that adheres to the bore wall surface and the crown surface 1131 of the piston 113, thereby reducing PN and KW. Furthermore, the control unit 21 controls the injection such that the penetration of the fuel injected during the second fuel injection 1002 in the compression stroke S2 ​​extends further. As a result, the fuel reaching the crown surface 1131 of the piston 113 is blown upwards towards the spark plug 110, and the air-fuel mixture around the spark plug 110 enters a fuel-rich state due to the blown-up fuel, thus improving combustion stability.Additionally, the adhesion of fuel to the borehole wall surface and the like can be reduced, and PN and KW can be suppressed.

[0064] (5) The control unit 21 is configured to control the injector 103 to extend the injection time (total time (p11 + p12 + p13) of the injection times (p11, p12 and p13)) of the fuel injected by the injector 103 at the first fuel injection 1001 compared to the injection time p14 of the fuel injected by the injector 103 at the second fuel injection 1002.

[0065] With this configuration, the control unit 21 controls the injector 103 such that, during the first fuel injection 1001 in the intake stroke S1, a low-pressure spray is performed for a longer period to achieve a short-penetration spray over an extended time. This can improve the homogeneity of the air-fuel mixture in the cylinder 1021. The control unit 21 can achieve a long-penetration spray over a short time by performing a high-pressure spray over an extended time during the second fuel injection 1002 in the compression stroke S2, allowing the spray to reach the cavity 1132 of the piston 113 to form a fuel-rich air-fuel mixture near the spark plug 110.

[0066] (6) Furthermore, the control unit 21 is configured to control the injector so that the first fuel injection 1001 in the intake stroke S1 is carried out several times in a fuel cycle of the internal combustion engine 100.

[0067] With this configuration, the control unit 21 can further improve the homogeneity of an air-fuel mixture in cylinder 1021 during the intake stroke S1 by performing a spray several times for a short time during the intake stroke S1.

[0068] (7) The control unit 21 is configured to control the injector 103 so that fuel is injected at a position where the displacement amount of the valve body of the injector 103 does not reach the maximum (maximum height Hmax) during the first fuel injection 1001.

[0069] In this configuration, the control unit 21 sprays fuel, while the displacement of the valve body 1036 of the injector 103 has not reached the maximum height position Hmax during the first fuel injection 1001. This allows for spraying with a short penetration during the first fuel injection 1001.

[0070] (8) The control unit 21 is configured to control the injector 103 so that fuel is injected at a position where the displacement amount of the valve body 1036 of the injector 103 reaches its maximum (maximum height Hmax) during the second fuel injection 1002.

[0071] In this configuration, the control unit 21 sprays fuel, while the displacement of the valve body 1036 of the injector 103 has reached its maximum height position Hmax during the second fuel injection 1002. This enables spraying with a long penetration during the second fuel injection 1002. [Second embodiment]

[0072] With reference to the Fig. In sections 11 to 16, an injector 600 according to the second embodiment of the present invention is described. Fig. Figure 11 is a cross-sectional view showing the structure of the injector 600 according to the second embodiment. Fig. Figure 12 is an enlarged view of the environment of a mover mechanism 610, showing a condition in which the mover mechanism 610 is pushed by a first spring 1110 towards a fuel injection port 1031. Fig. Figure 13 is an enlarged view of the environment of the mover mechanism 610, showing a short stroke state in which a second mover 611 of the mover mechanism 610 is attracted by the magnet coil 1032. Fig. Figure 14 is an enlarged view of the environment of the mover mechanism 610, showing a long-stroke state in which the first mover 611 and the second mover 612 are attracted by the magnet coil 1032. Fig. Figure 15 is a view showing an example of the drive current 400 supplied to the solenoid coil 1032 of the injector 600. Fig. Figure 16 is a view illustrating an example of the relationship between a fuel control signal 300 and a fuel injection quantity. The same components as those in the first embodiment described above are designated with the same reference numbers, and a detailed description thereof is omitted.

[0073] The injector 600 according to the second embodiment differs from the injector 103 according to the embodiment described above in that the mover that actuates a valve body 1033 is divided into two parts (the first mover 611 and the second mover 612, which together are referred to as the mover mechanism 610) and the displacement of the valve body 1033 in the direction of the X-axis can be adjusted incrementally (short stroke and long stroke). An engagement element 1100 (sleeve section) is attached to the upstream distal end section of the valve body 1033. The engagement element 1100 has a cylindrical section 1101 provided on the outer diameter side of the small-diameter section of the valve body 1033 and a projection 1102 that extends radially outward at its upper end (see Fig. 12).

[0074] The valve body 1033 is biased by the first spring 1110 via the projection 1102 of the engagement element 1100 towards the fuel injection port 1031 (downstream side) in the direction of the X-axis. Since the bias force of the first spring 1110 in the downstream direction is greater than the bias force of a third spring 1130 in the upstream direction, the valve body 1033 is biased towards the fuel injection port 1031 when the solenoid coil 1032 is de-energized, in order to move the injector 600 into the closed position of the valve. The lower surface of the projection 1102 of the engagement element 1100 holds a second spring 1120, which biases the actuator mechanism 610 towards the fuel injection port 1031 in the direction of the X-axis.

[0075] The mover mechanism 610 is configured to include the first mover 611 and the second mover 612, which is provided separately from the first mover 611 and independently of the valve body 1033.

[0076] The first mover 611 of the mover mechanism 610 has a first opposite surface 611a facing a magnetic core 620, and this first opposite surface 611a is attracted by the magnetic force of the magnetic core 620. The second mover 612 has a second opposite surface 612a facing the magnetic core 620, and this second opposite surface 612a is configured to be attracted by the magnetic force of the magnetic core 620. In this injector 600 configuration, the first mover 611 and the second mover 612 are drawn toward the magnetic core 620 by the magnetic force. This pushes the valve body 1033 upward in the valve opening direction.

[0077] The injector 600 is configured such that when the second mover 612 moves towards the magnetic core 620 due to the magnetic attraction generated between the magnetic core 620 and the second mover 612, the valve body 1033 moves along the X-axis towards the upstream side (in the direction in which the valve body 1033 moves away from the fuel injection port 1031), which accompanies the movement of the second mover 612 towards the magnetic core 620.

[0078] On the other hand, the second opposite surface 612a of the second mover 612 is arranged radially outside the first opposite surface 611a of the first mover 611.

[0079] An outer circumferential surface 611b of the first mover 611 is arranged such that it faces an inner circumferential surface 612b of the second mover 612 with a gap in one direction (horizontal direction) perpendicular to the direction of the X-axis.

[0080] A downstream end surface 611e of the first mover 611 is arranged such that it faces an upstream end surface 612e of the second mover 612 in the direction of the X-axis (the vertical direction in Fig. 12) It should be noted that the downstream end face 611e of the first mover 611 and the upstream end face 612e of the second mover 612, as in Fig. Figure 12 shows that in the closed state of the valve, neither the first mover 611 nor the second mover 612 are attracted to the magnetic core 620, they come into contact with each other.

[0081] As in Fig. As shown in Figure 12, the second mover 612 has a recess 612c, which is cut downstream of the second opposite surface 612a and formed on the inner diameter side, and the entire first mover 611 is housed in this recess 612c. In particular, when the valve is closed, and neither the first mover 611 nor the second mover 612 is attracted by the magnetic core 620, the first opposite surface 611a of the first mover 611 is located closer to the downstream side along the X-axis than the second opposite surface 612a of the second mover 612. In this state, a predetermined gap K1 is provided between the first opposite surface 611a and the second opposite surface 612a.

[0082] The valve body 1033 has a valve body engagement section 1033a that engages with the first mover 611. Although the embodiment illustrates the case in which the valve body 1033 and the engagement element 1100 are configured separately, the valve body 1033 and the engagement element 1100 can also be configured as a single piece. As the first mover 611 moves upstream along the X-axis, the first opposite surface 611a of the first mover 611 and a downstream end surface 1101a of the cylindrical section 1101 of the engagement element 1100 are brought into engagement, and the engagement element 1100 is pushed upwards toward the upstream side. The valve body 1033 then moves toward the upstream side (in the valve opening direction).

[0083] In this case, the downstream end surface 611e (first engagement section) of the first mover 611 engages with the second mover 612. As the second mover 612 moves upstream along the X-axis, the upstream end surface 612e (second engagement section) of the second mover 612 and the downstream end surface 611e (first engagement section) of the first mover 611 engage with each other to move the first mover 611 upstream. This causes the first opposite surface 611a of the first mover 611 to engage with the downstream end surface 1101a of the cylindrical section 1101 of the engagement element 1100 to push the engagement element 1100 upwards. This moves the valve body 1033, which engages with the engagement element 1100, towards the upstream side (in the direction of valve opening).

[0084] In the configuration described above, the valve body 1033 is driven upstream via the first mover 611 by the attraction of the second mover 612 by the magnetic attraction of the magnetic core 620.

[0085] As in Fig. As shown in Figure 12, a second spring 1120 is provided between the first mover 611 and the projection 1102 of the engagement element 1100. The second spring 1120 exerts a preload force in the direction in which the first mover 611 and the engagement element 1100 are separated from each other. A spring retainer 621 is provided on the downstream side of the mover mechanism 610, and the third spring 1130 is provided between the spring retainer 621 and the second mover 612. The third spring 1130 exerts a preload force in the direction in which the second mover 612 and the spring retainer 621 are separated from each other.

[0086] In this case, when the absolute value of the preload force Fz of the third spring 1130 is compared with the absolute value of the preload force Fm of the second spring 1120, the absolute value of the preload force of the second spring 1120 is set higher. Accordingly, when the drive current 400 is supplied to the magnetic coil 1032, a magnetic flux is generated in the gap between the magnetic core 620 and the second mover 612, which has an attractive surface formed on the outer diameter side (the second opposite surface 612a), and thus in the gap between the magnetic core 620 and the first mover 611, which has an attractive surface formed on the inner diameter side (the first opposite surface 611a). This generates a magnetic attraction force to attract the first mover 611 and the second mover 612.

[0087] As in the Fig. 11 and Fig. As shown in Figure 12, when the solenoid coil 1032 is de-energized, the first spring 1110 biases the engagement element 1100 along the X-axis towards the downstream side to bring a seat section 1033b of the valve body 1033 into contact with a seat surface 622a of a seat element 622, thereby closing the valve. In this case, the second spring 1120 biases the first mover 611 along the X-axis towards the downstream side to bias an upstream end surface 1033d (contact surface) of a projection 1033c (stepped section) provided on the valve body 1033 towards the downstream side. The valve body 1033 is stationary in this state.

[0088] The third spring 1130 biases the second mover 612 along the X-axis towards the upstream side (valve opening direction) in order to engage the upstream end face 612e of the second mover 612 with the downstream end face 611e (first engagement section) of the first mover 611, thereby holding the second mover 612 in a stationary state. In this stationary state, a gap K2 (see Fig. 11) between the first opposite surface 611a of the first mover 611 and a downstream end surface 1101a of the cylindrical section 1101 of the engagement element 1100.

[0089] If in the Fig. In the state shown in Figure 11, when the magnetic coil 1032 is supplied with drive current 400, magnetic attractive forces are generated between the magnetic core 620 and the first mover 611 and between the magnetic core 620 and the second mover 612.

[0090] As indicated by the following inequality (1), when the sum of a magnetic attraction force Fi acting between the first mover 611 and the magnetic core 620, and a magnetic attraction force Fo acting between the second mover 612 and the magnetic core 620 becomes greater than the difference between a preload force Fm of the second spring 1120 and a preload force Fz of the third spring 1130, the first mover 611 and the second mover 612 are attracted to the side of the magnetic core 620 and the valve body 1033 begins to move. Fi+Fo>Fm−Fz

[0091] When the first mover 611 is moved upstream along an X-axis by the preset gap K2 between the engagement element 1100 and the first mover 611 on the inner diameter side, a gap K3 (see Fig. 11) between a downstream end surface 620a of the magnetic core 620 and the second opposite surface 612a of the second mover 612 reduced to a gap K4 (see Fig. 12). In the embodiment, the relationship K3-K4 = k1 is established. The gap K4 can be described as the free space between the second opposite surface 612a of the second mover 612 and the downstream end surface 620a of the magnetic core 620, while the first opposite surface 611a of the first mover 611 is in contact with the downstream end surface 1101a of the cylindrical section 1101 of the engagement element 1100. In the embodiment shown in Fig. In the state shown in Figure 12, the first opposing surface 611a of the first mover 611 is in contact with the downstream end surface 1101a (contact surface) of the cylindrical section 1101 of the engagement element 1100. The gap K2 between the first opposing surface 611a of the first mover 611 and the downstream end surface 1101a of the cylindrical section 1101 of the engagement element 1100 can be referred to as the preliminary stroke. Due to this gap K2, the kinetic energy stored in the first mover 611 and the second mover 612 is used in the injector 600 for the valve opening process of the valve body 1033. The response of the valve opening process can be improved by the amount of kinetic energy used, and the valve can also be opened under high fuel pressure. To secure the gap K2 (provisional stroke), it is necessary to set the gap K3 larger than the gap K2 when the in Fig. Injector 600 shown in Figure 11 is in the closed state of the valve.

[0092] The in Fig. The state shown in Figure 13 is established when the magnetic coil 1032 is continuously supplied with drive current 400, and the second mover 612 is further displaced upstream along the X-axis by the gap K4, which is pre-defined between the second opposite surface 612a of the second mover 612 and the downstream end surface 620a of the magnetic core 620. In this state, the upstream movement of the second mover 612 along the X-axis is limited by the downstream end surface 620a of the magnetic core 620.

[0093] The relationship between the drive current 400 to the solenoid coil 1032 and the displacement amount of the valve body 1033 is described below. Fig. Figure 15(A) shows the relationship between the drive current 400 and the displacement amount of the valve body 1033 during a short stroke. Fig. Figure 15(B) shows the relationship between the drive current 400 and the displacement of the valve body 1033 during a long stroke. The embodiment illustrates by way of example a case in which a peak current 401 of the drive current 400 supplied to the solenoid coil 1032 is set to a lower value than a set value, as in Fig. 15 shown.

[0094] This case satisfies the force relation defined by inequality (2), i.e. a condition that the sum of the magnetic attraction force Fi acting on the first mover 611 and the magnetic attraction force Fo acting on the second mover 612 is greater than the sum of the differential pressure Fp due to the fuel (fluids) acting on the valve body 1033 and the preload force Fs of the first spring 1110.

[0095] Additionally, a control is provided to satisfy the force relation defined by inequality (3), i.e., a condition that the magnetic attraction force Fi acting on the first mover 611 is less than the sum of the differential pressure Fp due to fuel (fluid) acting on the valve body 1033 and the preload force Fs of the first spring 1110. Fs+Fp <Fi+Fo Fs+Fp>Fi

[0096] Therefore, in the case of the in Fig. 15(A) of the drive current 400 shown, when the control device 1 controls the injector 600 to satisfy the inequalities (2) and (3) described above, the second opposite surface 612a of the second mover 612 in contact with the downstream end surface 620a of the magnetic core 620 in order to eliminate the gap K4 between the second opposite surface 612a and the downstream end surface 620a and to leave only a gap K1 between the first opposite surface 611a of the first mover 611 and the downstream end surface 620a of the magnetic core 620, as in Fig. Figure 13 shows that, as indicated by inequality (2) described above, the valve body 1033 is displaced upstream along the X-axis when the magnetic attraction force Fo acting on the second mover 612 is received. However, as indicated by inequality (3) described above, the magnetic attraction force Fi acting on the first mover 611 alone cannot displace the valve body 1033. Consequently, the injector 600 is moved into a short-stroke state in which the valve body 1033 (second mover 612) is displaced upstream by an amount corresponding to the gap K4.

[0097] During the in Fig. 13. The displacement amount of the valve body 1033 shown corresponds to a short stroke state when the drive current 400 supplied to the solenoid coil 1032 is switched off or reduced to a current (intermediate current) lower than the peak current 401, the magnetic fluxes generated between the magnetic core 620 and the first mover 611 and between the magnetic core 620 and the second mover 612 are eliminated or reduced. Accordingly, if the sum (Fi + Fo) of the magnetic attraction force Fi acting on the first mover 611 and the magnetic attraction force Fo acting on the second mover 612 becomes smaller than the sum (Fs + Fp) of the preload force Fs of the first spring 1110 and the differential pressure Fp of the fuel (fluids) acting on the valve body 1033 (Fs + Fp > Fi + Fo), a displacement of the first mover 611 and the second mover 612 downstream along the X-axis begins.The valve body 1033 then begins a valve closing process. Afterwards, the seat section 1033b of the valve body 1033 comes into contact with the seat surface 622a of the seat element 622 to close the valve.

[0098] Therefore, in the case of the waveform of the drive current 400, as in Fig. As shown in Figure 15(A), the valve body 1033 is displaced by an amount corresponding to a valve body displacement 1601, which is provided between the second opposite surface 612a of the second mover 612 and the downstream end surface 620a of the magnetic core 620. The valve body displacement 1601 corresponds to that shown in Figure 15(A). Fig. 12 shown gap K4.

[0099] The second mover 612 is prevented from moving upstream in the direction of the X-axis by collision with the downstream end face 620a of the magnetic core 620 or with an element other than the magnetic core 620. This stabilizes the displacement of the valve body 1033 and therefore enables the injector 600 to implement stable fuel injection.

[0100] The following describes a case in which a peak current 402 of the drive current 400 supplied to the magnetic coil 1032 is increased compared to a preset value, as in Fig. Figure 15(B) shows that when the valve body 1033 is actuated in the long-stroke state, the peak current 402 in the long-stroke state is increased compared to the peak current 401 in the short-stroke state. In this case, as indicated by inequality (4) below, control is carried out to make the magnetic attraction force Fi acting on the first mover 611 greater than the sum of the preload force Fs of the first spring 1110 and the differential pressure Fp of the fluid (fuel) acting on the valve body 1033. Fs+Fp <Fi

[0101] Accordingly, as in Fig. As shown in Figure 14, the first mover 611 is displaced upstream along the X-axis by an amount corresponding to the gap K1 provided between the downstream end face 620a of the magnetic core 620 and the first opposite face 611a of the first mover 611. Consequently, the first mover 611 moves the valve body 1033 further upstream from the position shown in Figure 14 by an amount corresponding to the gap K1. Fig. In the state shown in Figure 13, the valve body 1033 moves upstream by a displacement amount equal to the sum of columns K4 and K1, compared to a de-energized state. In the injector 600, a state in which the valve body 1033 is displaced upstream by the displacement amount (K4 + K1) is referred to as the long-stroke state. It should be noted that the displacement of the first mover 611 is limited by collision with the magnetic core 620, so that the stabilization of the valve body 1033's behavior after the collision between the first mover 611 and the magnetic core 620 enables the injector 600 to implement stable fuel injection.

[0102] A control unit 21 switches off the drive current 400 supplied to the solenoid coil 1032 in the state in which the displacement of the valve body 1033 corresponds to a long stroke (which in Fig. (state shown in Figure 14), or reduces the drive current 400 to a current smaller than the peak current 402 (intermediate current). This eliminates or reduces the magnetic flux generated between the first mover 611 and the magnetic core 620. When the magnetic attraction Fi between them becomes smaller than the sum of the preload force Fs of the first spring 1110 and the pressure difference Fp of the fuel (fluids) acting on the valve body 1033 (Ps + Fp > Fi), the first mover 611 is displaced downstream along the X-axis.

[0103] The magnetic flux generated by the magnetic core 620 begins to disappear from the first mover 611, and the first mover 611 simultaneously initiates a valve closing operation earlier than the second mover 612 due to the pressure difference Fp of the fuel acting on the valve body 1033 and the preload force Fs of the first spring 1110. As a result, the first mover 611 is displaced downstream by the gap K1 between the downstream end face 611e of the first mover 611 and the upstream end face 612e of the second mover 612 and collides with the upstream end face 612e of the second mover 612. When the second mover 612 collides with the first mover 611, the second mover 612 is displaced downstream along with the first mover 611.

[0104] The valve body 1033 initiates a valve closing process, which is accompanied by the displacement of the first mover 611 and the second mover 612 described above, and the seat section 1033b of the valve body 1033 then comes into contact with the seat element 622 to close the valve. As a result, the valve body 1033, as described in Fig. Figure 15(B) shows a long stroke, and its displacement amount is as indicated by reference number 1602. The displacement amount 1602 corresponds to the total value of gap K4 and gap K1.

[0105] In this embodiment, varying the drive current 400 supplied to the solenoid coil 1032 of the injector 600 can cause the displacement of the valve body 1033 between the in Fig. 15(A) short stroke shown and the one in Fig. 15(B) shows switching long stroke. In the closed valve state of the injector 600, the first free space (gap K3 + gap K1 or gap K4 + gap K1) between the first opposite surface 611a of the first mover 611 and the magnetic core 620 is larger than the second free space (gap K3 or gap K4) between the second opposite surface 612a of the second mover 612 and the magnetic core 620.

[0106] In this case, the gap K2 can be defined as the free space between the first opposite surface 611a of the first mover 611 in the closed valve state and the downstream end surface 1101a of the cylindrical section 1101 of the engagement element 1100 (see Fig. 11) The gap K4 can be defined as the free space between the second opposite surface 612a of the second mover 612 and the downstream end surface 620a of the magnetic core 620, while the first opposite surface 611a of the first mover 611 is in contact with the downstream end surface 1101a of the cylindrical section 1101 of the engagement element 1100 (see Fig. 12) The gap K1 can be defined as the free space between the first opposite surface 611a of the first mover 611 and the downstream end surface 620a of the magnetic core 620, while the second opposite surface 612a of the second mover 612 is in contact with the downstream end surface 620a of the magnetic core 620 (see Fig. 13).

[0107] If the displacement of the valve body 1033 by the drive current 400 between the in Fig. 15(A) short stroke shown and the one in Fig. When switching to the long stroke shown in Figure 15(B), the gaps K1 and K4 in the injector 600 described above are preferably adjusted so that gap K1 > gap K4. Since the stroke adjustment is carried out during the assembly of the injector 600, gap K4 can be set with high accuracy. In this embodiment, gap K4 and gap K2, which determine a preliminary stroke amount, are adjusted so that they are substantially equal or satisfy gap K1 > gap K2.

[0108] In this way, the mover mechanism 610 of the injector 600 is divided into the first mover 611 and the second mover 612, and the control unit 21 changes the drive current 400 supplied to the solenoid coil 1032 to change the displacement amount of the valve body 1033 between the short and the long stroke.

[0109] Fig. Figure 16 shows the characteristic curves of the injection quantity (relationship between injection command periods and injection quantities) of injector 600 in the respective strokes. As with reference to Fig. As described in section 4, changing the waveform of the drive current 400 according to the required fuel injection quantity (fuel pressure) in the injector 600 can result in a long-stroke injection quantity characteristic 1701 and a short-stroke injection quantity characteristic 1702. Therefore, in the injector 600, when the required fuel pressure is high (the injection quantity is large), the long-stroke injection quantity characteristic 1701 is applied. Conversely, when the required fuel pressure is low (the injection quantity is small), applying the short-stroke injection quantity characteristic 1702 can provide a stable fuel supply at the optimal fuel pressure required for combustion in the internal combustion engine 100.

[0110] The control method of injector 600 according to the second embodiment is described with reference to the Fig. 15 and Fig. 17 described. Fig. Figure 17 is a view showing the temporal relationship between the fuel control signal 300, the drive current 400, and the displacement of a valve body 1033 according to the second embodiment of the present invention. The same reference numbers in Fig. 17 refer to the same parts as in Fig. 9.

[0111] The control method of injector 600 differs from the control method of injector 103 according to the first embodiment in that injector 600 is controlled to hold the valve body 1033 in a short-stroke state in order to inject fuel through injector 600 at a low fuel pressure for a predetermined period during the intake stroke S1 of a combustion cycle. As described above, the control unit 21 shifts the peak current supplied to the solenoid coil 1032 of injector 600 from peak current 420 (the drive current for moving the valve body 1033 with a long stroke) to peak current 410 (the drive current for moving the valve body 1033 with a short stroke). This allows the valve body 1033 to be held in a short-stroke state while the second mover 612 is kept in contact with the magnetic core 620.By keeping the valve body 1033 in a short-stroke state, the first fuel injection 1901 can occur at a low fuel pressure for a long time, such as injection period P21. Furthermore, the homogeneity of the air-fuel mixture in the cylinder can be improved by promoting the mixing of air and fuel. This makes it possible to reduce NOx in the exhaust gas and improve combustion stability due to the high homogeneity.

[0112] During a second fuel injection 1902 in the compression stroke S2 ​​following a first fuel injection 1901 in the same combustion cycle, the valve body 1033 can be moved into a long-stroke state by increasing the peak current of the actuator current 400 to a higher current than that of the first fuel injection 1901, up to a peak current of 420, and bringing the first actuator 611 into contact with the magnetic core 620. Due to the large displacement of the valve body 1033, fuel is injected with a long penetration (penetration force) from the injector 600. Accordingly, even with a small injection quantity, an air-fuel mixture can be caused to reach a spark plug 110 in a short time, and combustion stability can be improved.

[0113] Furthermore, since the first fuel injection 1901 is carried out during the intake stroke S1, in which the airflow in cylinder 1021 is strong, the homogeneity of the air-fuel mixture can be improved. On the other hand, to direct the fuel injected by injector 103 into a cavity 1132 of a piston 113 and blow the fuel upwards towards the spark plug 110, it is effective to carry out the second fuel injection 1902 during the compression stroke S2, when the piston 113 is approaching top dead center (TDC) from bottom dead center (BDC). It is particularly preferred to carry out the second fuel injection 1902 at a point 70 degrees (a slow point in a fuel cycle) before the crank angle reaches TDC during the compression stroke S2. During this process, a large proportion of the fuel spray mist D2 to D6 injected by injector 600 enters the cavity 1132 of piston 113, which is closer to injector 600.As a result, the fuel spray entering this cavity 1132 hits the inclined surface 1133 of the cavity 1132 and is blown upwards towards the spark plug 110, forming a fuel-rich air-fuel mixture around the spark plug 110.

[0114] In the second embodiment, the control unit 21 prestores the waveform of a drive current in the memory provided in a drive circuit 3 (not shown) and reads the waveform of the drive current from the memory according to the injection (not shown). This embodiment is configured to prestore the waveform of a drive current 430 for performing the first fuel injection 1901 and the waveform of a drive current 440 for performing the second fuel injection 1902 in the memory (not shown) of the drive circuit 3, and to read the waveform of the drive current 430 or 440 from the memory according to the required injection and to modify the waveform.Alternatively, the memory (not shown) of the drive circuit 3 can pre-store the waveform of the drive current 430, corresponding to the first fuel injection 1901, and the waveform of the drive current 440, corresponding to the second fuel injection 1902, as preset values. The waveform of the drive current stored in the memory (not shown) can be read out by the control unit 21 according to a control command value. As shown in . Fig. As shown in Figure 17, the control unit 21, for example, sends a control command value to switch an injection pulse 320 with a large pulse width to a drive circuit 400 (the solid line in Figure 17). Fig. 17) and an injection pulse of 330 with a small pulse width (the dotted line in Fig. 17), to cause the drive circuit 400 to read the drive currents 440 and 450 from the memory according to the control command value and output them to the injector 600.

[0115] When the control unit 21 in the embodiment outputs a control command value for the injection pulse 330 with a small pulse width to the drive circuit 400, the drive circuit 400 reads the current waveform 450 near the peak current value of a short stroke from the memory (the dotted line in Fig. 17) When the control unit 21 outputs a control command value for the injection pulse 330 with a long pulse width to the drive circuit 400, the drive circuit 400 reads the current waveform 440, close to the peak current value of a long stroke, from memory. Compared to the case where a current waveform is generated according to a required fuel injection quantity, it is possible to quickly change the current waveform simply by reading it from memory.

[0116] As described above, the set values ​​for the first fuel injection 1901 and the second fuel injection 1902 are assumed to be pre-stored in memory (not shown), and the set value of a drive current is changed according to a control command value from the control unit 21. In this case, the time to change control constants such as peak current and holding current can be reduced, so that the set value can be changed quickly when the current waveform switches several times in a combustion cycle, and the stability of the current control is improved. Fig. Figure 17 shows the case where a current waveform is changed in two steps during a combustion cycle (the short-stroke current waveform 450 and the long-stroke current waveform 440). However, the actual waveform can be changed in two or more steps.

[0117] The above embodiments have illustrated, by way of example, the configurations in which the injectors 103 and 600 are mounted on the sides of the cylinders 1021. However, the embodiment is also effective for a so-called directional configuration in which the injector 103 or 600 is mounted in the center of the cylinder head in the cylinders 1021. In the direct system, the penetration force of the second fuel injection 1902 may not always be required, since the distance between the injector and the spark plug is reduced. In this case, fuel can be injected in a short-stroke state during the second fuel injection 1902, as in the first fuel injection 1901.

[0118] As described above, in the second embodiment (9) the control unit 21 is configured to control the injector 103 such that the second mover 612 is held in a position where the displacement amount of the second mover 612 of the injector 103 is at its maximum during the first fuel injection 1001.

[0119] In this configuration, the valve body 1033 of injector 600 is held in place during the first fuel injection 1001, while it is moved upstream along the X-axis by the maximum displacement amount (first variable amount) of the second mover 612. This can stabilize the fuel sprayed by injector 600 in a low fuel pressure condition.

[0120] (10) The control unit 21 is configured to change the magnitude of the peak value of the drive current 400, which controls the injector 600, at least once during the same combustion cycle in the internal combustion engine 100. With this configuration, the control unit 21 can supply the injector 600 with drive currents 400 with different peak currents (for example, drive current 440 and drive current 450) at least once during a combustion cycle. Fig. 17) supply, whereby the spraying of fuel in the first fuel injection 1001 and the second fuel injection 1002 takes place without further ado at different fuel pressures.

[0121] Although an example of each embodiment of the present invention has been described above, the present invention may be a combination of all the above embodiments or a combination of two or more embodiments.

[0122] Furthermore, the present invention is not limited to that which includes all configurations of the embodiments mentioned above, and part of the configuration of the embodiment mentioned above can be replaced by the configuration of another embodiment. The configuration of the embodiment mentioned above can be replaced by the configuration of another embodiment.

[0123] Furthermore, part of the configuration of each embodiment described above can be added to, removed from, and replaced with respect to the configurations of other embodiments. Reference number list 1 Control device 2 ECU 3 Drive circuit 4 Fuel injection system 5 different types of sensors 100 internal combustion engine 101 cylinder block 102 cylinders 1021 first cylinder 1022 second cylinder 1023 third cylinder 1024 fourth cylinder 103-106 Injector 107 Fuel pump 108 Rail line 109 Pressure sensor 110 Spark plug 111 Intake opening 112 Exhaust opening 113 pistons 114 Inlet valve 115 Exhaust valve 116 Partition wall 117 Valve 120 air filters 121 chargers 122 Loading chamber 123 Intercooler 124 Throttle valve 125 wave 126 Crankshaft 127 Catalyst 300 Fuel control signal 400 drive current 500 drive voltage 600 injectors 610 mover mechanism 611 first mover 612 second mover 620 magnetic core 1001 first fuel injection 1002 second fuel injection 1031 Fuel injection port 1032 Magnetic coil 1033 Valve body 1033a Engagement part of the valve body 1033b Seating section 1033c lead 1033d upstream end face 1034 spring 1035 Valve seat 1036 movers 1036a End area 1037 spring 1038 nozzle holders 1038a End area 1039 solid core 1041 Housing 1042 Magnetic membrane 1044 Rod guide 1045 Opening 1046 first fuel channel 1047 lower fuel channel 1100 intervening element 1101 cylindrical part 1101a End surface of the other side of the flow 1102 lead 1110 first spring 1120 second spring 1130 third spring 1131 Crown surface 1132 Cavity 1133 inclined surface D1-D6 Spray mist S1 intake stroke S2 compression stroke

Claims

[1] Injector control device for controlling an injector, wherein the control device comprises a control unit that controls the injector to perform a first fuel injection to inject fuel at a first fuel pressure from the injector in an intake stroke in a combustion cycle of an internal combustion engine and a second fuel injection to inject fuel at a second fuel pressure higher than the first fuel pressure from the injector after the first fuel injection in the same combustion cycle in the intake stroke. [2] Injector control device according to claim 1, wherein the control unit controls the injector such that the second fuel injection is carried out in the compression stroke in the same combustion cycle as the intake stroke in which the first fuel injection is carried out. [3] Injector control device according to claim 1, wherein the control unit controls the injector such that the displacement amount of a mover of the injector during the first fuel injection is smaller than the displacement amount of the mover of the injector during the second fuel injection. [4] Injector control device according to claim 1, wherein the control unit controls the injector in such a way that the penetration of fuel injected during the second fuel injection extends further than the penetration of fuel injected during the first fuel injection. [5] Injector control device according to claim 3, wherein the control unit controls the injector such that the mover is held in a position where the displacement amount of the mover of the injector is maximal during the first fuel injection. [6] Injector control device according to claim 1, wherein the control unit controls the injector such that the injection time of fuel injected by the injector during the first fuel injection is longer than the injection time of fuel injected by the injector during the second fuel injection. [7] Injector control device according to claim 1, wherein the control unit controls the injector such that the first fuel injection is carried out several times in one intake stroke in one fuel cycle in the internal combustion engine. [8] Injector control device according to claim 1, wherein the control unit controls the injector such that fuel is injected at a position where the displacement of a valve body of the injector is not at its maximum during the first fuel injection. [9] Injector control device according to claim 1, wherein the control unit controls the injector such that fuel is injected at a position where the displacement of a valve body of the injector is maximal during the second fuel injection. [10] Injector control device according to claim 1, wherein the control unit changes the magnitude of a peak value of a current controlling the injector at least once in the same combustion cycle in the internal combustion engine.

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