CONTROL DEVICE FOR A FUEL INJECTION VALVE AND FUEL INJECTION SYSTEM

Abstract

Control device (60) configured to control a drive current flowing through a drive coil (52) of a fuel injector (21) configured to be electromagnetically driven, the control device comprising the following: a determination unit configured to determine whether a fuel supply pressure, which is a pressure of the fuel supplied to the fuel injector, is higher than a determination pressure at which the fuel pressure is determined to be abnormally high; a first control unit configured to control the drive current in a first mode when the determining unit determines that the fuel supply pressure is not higher than the determining pressure; and a second control unit configured to control the drive current in a second mode, which allows the fuel injector to be held in an open state more strongly than in the first mode when the determining unit detects that the fuel supply pressure is higher than the determining pressure, wherein a voltage applied to the drive coil when the drive current is increased to a maximum value in an injection period in the second operating mode is higher than a voltage applied to the drive coil when the drive current is increased to a maximum value in an injection period in the first operating mode.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a control device that controls the drive current of an electromagnetically driven fuel injection valve. STATE OF THE ART

[0002] Conventionally, a control device applies a high voltage to a drive coil of an electromagnetically driven fuel injection valve to quickly increase a drive current to a target peak current and then intermittently applies a low voltage to the drive coil to keep the drive current at a holding current (see Patent Literature 1).

[0003] DE 10 2016 219 888 B3 discloses the following: A method for operating a fuel injector with a hydraulic stop at a predetermined fuel pressure is described, wherein the fuel injector has a solenoid drive with a solenoid and a movable armature. The method comprises the following: applying a first current profile to the solenoid drive in order to perform a first injection process, wherein the first current profile has a first holding current value that specifies the current intensity of the current flowing through the solenoid during a holding phase; determining a first flux value that corresponds to the magnetic flux in the holding phase; determining a first force value based on the first flux value, wherein the first force value corresponds to a hydraulic force exerted by fuel on the armature during the holding phase;Determining a deviation between the first force value and an optimal force value corresponding to the predetermined fuel pressure, and applying a second current profile to the solenoid drive of the fuel injector to perform a second injection process, wherein the second current profile has a second holding current value determined based on the first holding current value and the determined deviation such that the hydraulic force exerted by the fuel on the armature during the holding phase is adjusted to the optimal force value. An engine control system and a computer program are also described.

[0004] US 2004 / 0 040 545 A1 discloses the following: A method for controlling a fuel injection valve using a fuel supply pressure detector involves various types of delays, including a response delay of the fuel supply pressure detector, a delay caused by a noise filter of a signal processing circuit, and a delay caused by a software filter provided in a computing unit. These delay factors result in a delay in increasing the current value supplied to the fuel injection valve, despite the fact that the actual fuel supply pressure is already high. Then, no attractive force is generated in the fuel injection valve to overcome the fuel supply pressure, resulting in a state in which no fuel is injected because the fuel injection valve is not open.An overexcitation current and a holding current supplied to the fuel injection valve according to a target fuel supply pressure determined from an operating condition are controlled, thereby controlling the opening and holding of the open position of the fuel injection valve.

[0005] JP 2014-98375 A discloses the following: In a control device for controlling a drive current applied to a fuel injection valve having a solenoid, the drive current applied based on an injection pulse for injecting fuel is determined by the fuel pressure applied to the fuel injection valve or a predicted fuel pressure based thereon and the engine speed or a predicted engine speed based thereon, whether the drive current flowing through the solenoid should be controlled until a valve body can no longer be opened or whether the above control is required, and an injection pulse width is calculated in a process from fuel pressure, fuel temperature, engine speed, and injection frequency. Furthermore, the holding time of the drive current at a maximum value and a minimum value is similarly controlled.

[0006] JP 2016-75171 A discloses the following: An ECU calculates a peak current arrival time Tp' (time until a detection current arrives at a peak current Ip) and calculates a prescribed current arrival difference time ΔTth (time until the detection current decreases below a prescribed current Ith after exceeding the prescribed current Ith). Then, using a relationship between the prestored prescribed current arrival difference time ΔTth and a regulated peak current arrival time Tp, the ECU calculates the regulated peak current arrival time Tp corresponding to the currently prescribed current arrival difference time ΔTth.By comparing the actual peak current arrival time Tp' and the regulated peak current arrival time Tp using the regulated peak current arrival time Tp (for example, by calculating a difference ΔTp between the circuit peak current arrival time Tp' and the regulated peak current arrival time Tp), the ECU determines the deviation of a detection current of a current detection circuit. STATE OF THE TECHNICAL PATENT LITERATURE

[0007] PATENT LITERATURE 1: JP 2016-75171 A SUMMARY OF THE INVENTION

[0008] It should be noted that the drive coil generally requires a large drive current to drive the fuel injection valve to inject fuel as the pressure of the fuel supplied to the fuel injection valve (hereinafter referred to as "fuel supply pressure") increases. Therefore, in a case where the fuel supply pressure increases excessively due to an abnormality caused by the fuel pump or the like, fuel may not be injected through the fuel injection valve even if the drive current is increased to the target peak current.

[0009] The present disclosure has been made to solve the above-mentioned problems. A main object of the present disclosure is to provide a fuel injection valve control device configured to allow a fuel injection valve to perform fuel injection and suppress an increase in power consumption even when the fuel supply pressure increases excessively.

[0010] The object is achieved by the device having the features of claim 1, claim 4, claim 6, claim 10, and claim 13. Further advantageous developments and embodiments of the invention are the subject of the respective subsequent claims.

[0011] A first aspect for solving the above problem is a control device configured to control a drive current flowing through a drive coil of a fuel injection valve that is electromagnetically driven.The control device includes a determination unit configured to determine whether a fuel supply pressure, which is a pressure of the fuel supplied to the fuel injection valve, is higher than a determination pressure at which the fuel pressure is determined to be abnormally high; a first control unit configured to control the drive current in a first mode when the determination unit determines that the fuel supply pressure is not higher than the determination pressure; and a second control unit configured to control the drive current in a second mode that makes it easier for the fuel injection valve to remain in an open state more than in the first mode when the determination unit determines that the fuel supply pressure is higher than the determination pressure.

[0012] According to the above configuration, the drive current flowing through the drive coil of the electromagnetically driven fuel injection valve is controlled by the control device. At this time, the determination unit determines whether the fuel supply pressure, that is, the pressure of the fuel supplied to the fuel injection valve, is higher than the determination pressure, with which it is determined that the fuel pressure is abnormally high. Moreover, in a case where it is determined that the fuel supply pressure is not higher than the determination pressure, the drive current is controlled by the first control unit in the first mode. Alternatively, in a case where it is determined that the fuel supply pressure is higher than the determination pressure, the drive current is controlled by the second control unit in the second mode, which allows the fuel injection valve to be maintained in the open state more than the first current pattern.Therefore, the configuration allows the fuel injection valve to perform fuel injection even when the fuel supply pressure is higher than the target pressure. Generally, the power consumption in the second mode is greater than the power consumption in the first mode. In this regard, the drive current is controlled in the first operating mode when the fuel supply pressure is not higher than the target pressure, that is, when the fuel supply pressure is normal. Therefore, the configuration allows suppression of an increase in power consumption.

[0013] According to a second aspect, the determination pressure is a pressure at which the fuel injection valve is unable to inject fuel when the drive current is controlled in the first mode.

[0014] According to the configuration described above, the fuel injection valve cannot inject fuel when the fuel supply pressure becomes higher than the target pressure and when the drive current is controlled in the first mode. In this case, the configuration controls the drive current in the second operation mode, thereby allowing the fuel injection valve to inject fuel.

[0015] According to a third aspect, the determination pressure is a pressure at which the fuel injection valve is unable to be in a fully open state when the drive current is controlled in the first mode.

[0016] According to the configuration described above, the fuel injection valve cannot be in the fully open state when the fuel supply pressure becomes higher than the target pressure and the drive current is controlled in the first mode. In this case, the configuration controls the drive current in the second mode, allowing the fuel injection valve to be fully opened to inject fuel.

[0017] As a fuel injection valve configured to inject fuel at a higher fuel supply pressure, there is a core-boost fuel injection valve that moves a valve body using a core after accelerating and moving the core with the electromagnetic force generated by using the drive coil. In the core-boost fuel injection valve, the drive current required to move the core and the valve body becomes larger than the drive current required to move only the core. Therefore, the valve body cannot be moved to the fully open position unless the drive current when moving the core and the valve body is larger than a predetermined current.

[0018] In this regard, according to a fourth aspect, a voltage applied to the drive coil when the drive current is increased to a maximum value in an injection period in the second mode is higher than a voltage applied to the drive coil when the drive current is increased to a maximum value in an injection period in the first mode. Therefore, in a case where the control device is applied to the core boost fuel injection valve, the configuration facilitates increasing the drive current to be larger than a predetermined current when the valve body is moved. Therefore, the configuration makes it possible to cause the fuel injection valve to inject fuel at a higher fuel supply pressure. It should be noted that the maximum value of the drive current in the first mode and the maximum value of the drive current in the second mode may be the same or different.

[0019] According to a fifth aspect, the second mode comprises a control for continuously maintaining the drive current after increasing the drive current to a maximum value in an injection period and a control for reducing the drive current from the maximum value to a holding value in the injection period and for maintaining the drive current.

[0020] According to the above configuration, when controlling the drive current in the second operation mode, the drive current is continuously maintained after being increased to the maximum value in the injection period. Therefore, the configuration enables the continuous maintenance of the electromagnetic force generated by using the drive coil after the electromagnetic force is increased to the maximum value. In addition, the configuration makes it possible to facilitate the opening of the fuel injection valve and maintain the fuel injection valve in the open state. Furthermore, the configuration reduces the drive current from the maximum value to the holding value and maintains the drive current. Therefore, the configuration enables the suppression of power consumption when the fuel injection valve is maintained in the open state.

[0021] According to a sixth aspect, the first mode includes a controller for increasing the drive current to the maximum value in the injection period and then continuously decreasing the drive current to the holding value and maintaining the drive current. The maximum value of the drive current in the injection period in the second mode is greater than the maximum value of the drive current in the injection period in the first mode.

[0022] According to the above configuration, in the first mode drive current control, the drive current is continuously maintained after being increased to the maximum value in the injection period and reduced to the holding value.

[0023] In contrast, when controlling the drive current in the second mode, the drive current is maintained at the maximum value, which is larger than the maximum value of the drive current during the injection period in the first mode. Therefore, this configuration makes it easier to keep the fuel injection valve open in the second mode compared to the first mode.

[0024] According to a seventh aspect, the first mode includes a controller for increasing the drive current to the maximum value in the injection period and then continuously decreasing the drive current to the holding value and maintaining the drive current. The maximum value of the drive current in the injection period in the second mode is smaller than the maximum value of the drive current in the injection period in the first mode.

[0025] According to the above configuration, in the drive current control in the first mode, the drive current is continuously maintained after being increased to the maximum value in the injection period and reduced to the holding value. In contrast, in the drive current control in the second mode, the drive current is maintained at the maximum value, which is smaller than the maximum value of the drive current in the injection period in the first mode. That is, even in a case where the maximum value of the drive current in the injection period in the second mode is smaller than the maximum value of the drive current in the injection period in the first mode, the configuration continuously maintains the drive current after increasing the drive current to the maximum value in the injection period, thereby facilitating the maintenance of the open state of the fuel injection valve.The configuration therefore makes it easier to keep the fuel injection valve open and suppresses an increase in power consumption.

[0026] The higher the speed of an engine equipped with a fuel injector, the shorter the interval between fuel injection and fuel injection. Therefore, when the drive current is maintained at its maximum value, heat generated by the control device tends to accumulate. Therefore, the temperature of the control device may exceed the heat-resistant temperature.

[0027] In this regard, according to an eighth aspect, the second control unit is configured to set a period in which the second control unit continuously maintains the drive current after increasing the drive current to the maximum value in the injection period, so that the period becomes shorter as the rotational speed of the engine on which the fuel injection valve is mounted increases. Therefore, the configuration makes it possible to protect the temperature of the control device from exceeding the heat-resistant temperature even when the rotational speed of the engine equipped with the fuel injection valve increases.

[0028] In a case where the fuel supply pressure is high, even if the fuel injection valve is once in the open state, the fuel injection valve may return to the closed state until the fuel injection valve is stabilized in the open state.

[0029] In this regard, according to a ninth aspect, the second control unit is configured to set a period in which the second control unit continuously maintains the drive current after increasing the drive current to the maximum value in the injection period to a period until the fuel injection valve is stabilized in the open state. Therefore, in a case where the drive current is controlled in the second mode, the configuration makes it possible to increase the drive current to the maximum value during the injection period and then maintain the drive current at the maximum value until the fuel injection valve is stabilized in the open state. Even if the fuel supply pressure increases excessively, the configuration makes it possible to cause the fuel injection valve to perform stable fuel injection.The time until the fuel injection valve stabilizes in the open state can be determined in advance based on an experiment or the like.

[0030] If the period of continuous control of the drive current in the second mode becomes too long, the temperature of the control device may exceed the heat-resistant temperature.

[0031] In this regard, according to a tenth aspect, the second control unit is configured to change the drive current in the second mode to the drive current in the first mode when the period in which the second control unit continuously controls the drive current in the second mode becomes longer than a predetermined period. Therefore, when the temperature of the control device continuously rises due to the control of the drive current in the second mode, the control device changes the drive current to be in the first mode, thereby suppressing the temperature rise of the control device.

[0032] In this regard, according to an eleventh aspect, the second control unit is configured to change the drive current in the second mode to the drive current in the first mode when the fuel supply pressure becomes equal to or lower than the determination pressure.

[0033] According to the above configuration, the drive current in the second mode is changed to the drive current in the first mode when the fuel supply pressure becomes equal to or lower than the target pressure. Therefore, this configuration allows the drive current in the second mode to be suppressed more than necessary, thereby suppressing the temperature rise of the control device and the increase in power consumption.

[0034] According to a twelfth aspect, the first mode includes control for applying a voltage in a direction to decrease the drive current to the drive coil after the drive current is increased to a maximum value in an injection period, and the second mode does not include control for applying the voltage in the direction to decrease the drive current to the drive coil after the drive current is increased to a maximum value in an injection period.

[0035] According to the above configuration, when controlling the drive current in the first mode, the drive current is increased to the maximum value in the injection period, and then the voltage in the direction of decreasing the drive current is applied to the drive coil. This configuration makes it possible to suppress noise generated when the fuel injection valve enters the fully open state. In contrast, when controlling the drive current in the second mode, the drive current is increased to the maximum value in the injection period, and then the voltage in the direction of reducing the drive current is not applied to the drive coil. Therefore, when the fuel supply pressure increases excessively, the configuration makes it possible to prioritize the ease of maintaining the open state of the fuel injection valve over noise suppression. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The above and other objects, features, and advantages of the present disclosure will become more apparent from the following detailed description, which was prepared with reference to the accompanying drawings. In the drawings / figures: Fig. 1 is a schematic diagram showing an overview of an engine and a fuel injection system; Fig. 2 is a cross-sectional view showing the fuel injection device; Fig. 3 is an enlarged cross-sectional view showing a state of the fuel injection valve in the non-energized state; Fig. 4 is an enlarged cross-sectional view showing a state of the fuel injection valve in the energized state; Fig. 5 is an enlarged cross-sectional view showing a state of the fuel injection valve in the energized state; Fig. 6 is a block diagram showing a configuration of an ECU; Fig. 7 is a time chart showing a drive current pattern when the fuel supply pressure is normal; Fig. 8 is a timing chart showing the driving current, a suction force, and a core lift amount when the fuel injection valve is not fully opened; Fig. 9 is a timing chart showing the driving current, suction force, and core lift amount when the fuel injection valve is not fully opened and unstable; Fig. 10 is a timing chart showing the drive current, suction force, and core lift amount when the fuel injection valve is fully opened and stabilized with a single-peak drive current; Fig. 11 is a timing chart showing the drive current, suction force, and core lift amount when the fuel injection valve is fully opened and stabilized with a multi-peak drive current; Fig. 12 is a timing chart showing the drive current, suction force, and core lift amount when the fuel injection valve is fully opened and stabilized with a drive current that is increased in slope before several peaks; Fig. 13 is a timing chart showing an example of a drive current pattern set when the fuel supply pressure is abnormally high; Fig. 14 is a schematic diagram showing examples of combinations of a peak shape of the drive current, the presence / absence of a pickup control, and the magnitude of the drive voltage; Fig. 15 is a flowchart showing the procedure of drive current control; Fig. 16 is a timing chart showing a continuous protection value and an elapsed time protection value; Fig. 17 is a graph showing a relationship between a motor speed and the continuous protection value; Fig. 18 is a graph showing a relationship between a previous time period and the elapsed time protection value; Fig. 19 is a time chart showing a drive current pattern when the fuel supply pressure is normal according to a modified example; and Fig. 20 is a time chart showing a relationship between the fuel supply pressure and a relief pressure. DESCRIPTION OF THE EMBODIMENTS

[0037] An embodiment of a fuel injection system applied to an engine mounted on a vehicle will be described below with reference to the drawings / figures.

[0038] First, a schematic diagram of a configuration of an engine 11 is shown using Fig. 1 described.

[0039] An air cleaner 13 is provided at the upstream portion of an intake pipe 12 of the cylinder-injection type engine 11. An air flow meter 14 is provided downstream of the air cleaner 13 to detect an intake air amount. A throttle valve 16, whose opening is adjusted by a motor 15, and a throttle opening sensor 17, which detects the opening degree (throttle opening degree) of the throttle valve 16, are provided downstream of the air flow meter 14.

[0040] A surge tank 18 is provided on the downstream side of the throttle valve 16. The surge tank 18 is equipped with an intake manifold pressure sensor 19 that detects intake manifold pressure. The surge tank 18 is provided with an intake manifold 20 that supplies air to each cylinder of the engine 11. Each cylinder of the engine 11 is provided with a fuel injection valve 21 that injects fuel directly into the cylinder. A spark plug 22 is mounted on each cylinder head of the engine 11. The spark plug 22 in each cylinder causes a spark discharge to ignite the air-fuel mixture in each cylinder.

[0041] An exhaust pipe 23 of the engine 11 is provided with an exhaust gas sensor 24 (air-fuel ratio sensor, oxygen sensor, or the like) that detects an air-fuel ratio or a rich / lean condition of the exhaust gas. A catalyst 25, such as a three-way catalyst, for purifying exhaust gas is provided downstream of the exhaust gas sensor 24.

[0042] A cooling water temperature sensor 26 for detecting cooling water temperature and a knock sensor 27 for detecting knocking are mounted on a cylinder block of the engine 11. A crank angle sensor 29, which outputs a pulse signal each time a crankshaft 28 rotates by a predetermined crank angle, is mounted on the outer peripheral side of the crankshaft 28. The crank angle and the engine speed are detected based on an output signal of the crank angle sensor 29. A fuel supply system (e.g., a delivery line) that supplies fuel to the fuel injection valve 21 is provided with a fuel pressure sensor 57 that detects a pressure (fuel supply pressure) of the fuel supplied to the fuel injection valve 21. The fuel is supplied into the delivery line under pressure by a fuel pump (not shown).

[0043] The output signals of these various sensors are input to an electronic control unit (hereinafter referred to as "ECU") 60. The ECU 60 (fuel injection valve control device) essentially comprises a microcomputer and executes various engine control programs stored in a ROM (storage medium) to control the supply pressure, fuel injection amount, ignition timing, throttle opening (intake air amount), and the like depending on the engine operating condition. The fuel injection system is constituted by the fuel injection valve 21, the fuel pressure sensor 57, and the ECU 60. The detailed configuration of the ECU 60 will be described later.

[0044] Next, the outline of the configuration of the fuel injection valve 21 will be described with reference to the Fig. 2 to 5.

[0045] As in Fig. As shown in Fig. 2, a main body housing 32 of the fuel injection valve 21 is formed by connecting a third tubular member 35 to a lower end portion of a first tubular member 33 via a tubular member 34. The first tubular member 33 and the third tubular member 35 are formed of a magnetic material. The second tubular member 34 is made of a non-magnetic material. A fuel connection part 36 is connected to an upper end portion of the main body casing 32 (upper end portion of the first tubular member 33), which is connected to an exhaust pipe (not shown). A fuel filter 37 that filters fuel is attached to the radially inner side of the fuel connection part 36.

[0046] A cylindrical fixed core 38 made of a magnetic material is provided on the radially inner side of the main body with the housing 32. A tubular adjuster 39 is provided on the radially inner side of the fixed core 38. A tubular movable core 40 made of a magnetic material is provided on the underside of the fixed core 38 so as to be movable in the opening / closing direction (vertical direction in Fig. 2 to 5). The movable core 40 is provided as a separate component of a needle 41, which opens and closes the injection holes 49. The needle 41 is movably inserted in the opening and closing directions on the radially inner side of the movable core 40.

[0047] As in Fig. 3, a collar portion 42 having an outer diameter larger than the inner diameter of the movable core 40 is provided at the upper end of the needle 41. The flange 42 protrudes beyond the movable core 40. A tapered portion 40a (pressing portion) formed on the upper side of the movable core 40 comes into contact with the underside of the collar portion 42 (pressing portion) of the needle 41, so that the movable core 40 presses the needle 41 in the valve opening direction (in the upper direction in Fig. 2 to 5) opens.

[0048] On the top of the needle 41, a tubular cup 43 with a bottom is provided, which is movable in the opening / closing direction and covers the collar portion 42 of the needle 41. An outer peripheral wall 44 of the cup 43 is in contact with the upper surface of the movable core 40 (the radially outer side of the conical portion 40a). The depth of the outer peripheral wall 44 of the cup 43 is set to be greater than the height of the collar portion 42 of the needle 41.

[0049] A first spring 45, which is a biasing element, is provided between the cup 43 and the adjuster 39 (see Fig. 2). The first spring 45 biases the cup 43 in the closing direction of the valve (in Fig. 2 to 5 downwards) and thereby pushes the needle 41 and the movable core 40 in the valve closing direction. A ring member 46 is attached to the outer peripheral surface of the needle 41 at the bottom of the movable core 40. A second spring 47 is provided between the ring member 46 and the movable core 40. The movable core 40 is biased toward the valve opening by the second spring 47. The spring force (preload force) of the second spring 47 is set to be smaller than the spring force (preload force) of the first spring 45.

[0050] As in Fig. As shown in Fig. 2, a nozzle portion 48 is provided at the lower end portion of the main body casing 32 (the lower end portion of the third tubular member 35). A plurality of injection holes 49 are formed in the nozzle portion 48. When a valve body 50 at the lower end (tip) of the needle 41 is separated (lifted) from a valve seat 51 of the nozzle portion 48, the injection hole 49 is opened, and fuel is injected. When the valve body 50 abuts (seats) against the valve seat 51, the injection holes 49 are closed, and fuel injection is stopped.

[0051] A solenoid 52 (drive coil) or a solenoid 52, which drives the movable core 40 in the valve-opening direction, is arranged on the radially outer side of the main body casing 32. A terminal 54 connected to the solenoid 52 is located in a connector 53 provided above the solenoid 52.

[0052] As in Fig. 3, when the solenoid coil 52 is de-energized, the cup 43 is moved in the valve closing direction by the spring force of the first spring 45. As a result, the needle 41 and the movable core 40 are pushed by the cup 43 in the valve closing direction, and the fuel injection valve 21 is closed (injection holes 49 are closed). At this time, the valve body 50 of the needle 41 contacts the valve seat 51, thereby controlling the lower end position of the needle 41, and this lower end position becomes the valve closing position of the needle 41. As described above, the depth of the outer peripheral wall 44 of the cup 43 is set to be greater than the height of the collar portion 42 of the needle 41. Therefore, the fuel injection valve 21 has a configuration (so-called core boost orCore reinforcement configuration) in which a predetermined gap is formed between the tapered portion 40a of the movable core 40 and the collar portion 42 of the needle 41 when the solenoid coil 52 is not energized.

[0053] In contrast, when the magnetic coil 52 is excited, as shown in Fig. 4, the movable core 40 is moved toward the valve opening by the electromagnetic attraction (electromagnetic force) of the solenoid coil 52. As a result, the cup 43 is pushed by the movable core 40 and moves toward the valve opening, and the conical part 40a of the movable core 40 abuts the collar part 42 of the needle 41. Subsequently, as shown in Fig. 5, the needle 41 and the cup 43 are pushed toward the valve opening by the movable core 40, and the fuel injection valve 21 is opened (the injection hole 49 is opened). At this time, the upper surface of the movable core 40 comes into contact with a stopper 55, so that the upper end position of the movable core 40 is regulated. This regulates the upper end position of the needle 41, and this upper end position becomes the full-lift position of the needle 41.

[0054] Next, the configuration of the ECU 60 is carried out using Fig. 6 described.

[0055] The ECU 60 is equipped with an engine control microcomputer 61 (microcomputer for controlling the engine 11), an injector drive IC 62 (control IC for the fuel injection valve 21), and the like. The engine control microcomputer 61 calculates a required injection amount in accordance with an engine operating condition (such as engine speed and engine load). The engine control microcomputer 61 calculates an injection pulse width (injection timing) corresponding to the required injection amount. The injector drive IC 62 drives the fuel injection valve 21 to open with an injection pulse width corresponding to the required injection amount and performs fuel injection by the required injection amount.At this time, the ECU 60 causes a voltage switching circuit 63 to switch the drive voltage of the fuel injection valve 21 (the voltage applied to the solenoid valve 52) between a low voltage supplied by a low-voltage power supply 64 and a high voltage supplied by a boost power supply 65 (the voltage boosted to open the valve). For example, the low-voltage power supply 64 is a 12V battery, and the boost power supply 65 is a boost circuit that increases the battery's supply voltage. The ECU 60 detects the drive current of the fuel injection valve 21 (the current flowing through the magnet 52 or solenoid) with a current detection circuit 66 (current detector).

[0056] The ECU 60 (at least one of the two microcomputers engine control unit 61 and injector control unit IC-62) functions as a control device that controls the drive current of the fuel injection valve 21 when it controls the fuel injection valve 21 to open. Fig. Figure 7 shows an example of the drive current pattern (first current pattern) when the fuel supply pressure is normal. The drive current of the fuel injection valve 21 is controlled after the injection pulse is turned on in the order of a precharge phase, a boost drive phase, a pickup phase, and a hold phase.

[0057] First, in the precharge phase, a low voltage is applied to the solenoid valve 52 of the fuel injection valve 21 to gently increase the drive current.

[0058] Thereafter, in the boost drive phase, a high voltage (voltage boosted to open the valve) is applied to the solenoid valve 52 of the fuel injection valve 21 to quickly increase the drive current to a predetermined target peak current, thereby opening the valve body 50 (needle 41) of the fuel injection valve 21. When the drive current detected by the current detection circuit 66 (hereinafter referred to as "detection current") reaches the target peak current, the application of the high voltage is stopped.

[0059] Subsequently, in the pickup phase, a low voltage is intermittently applied to the solenoid valve 52 of the fuel injection valve 21 to maintain the drive current around a pickup current lower than the target peak current, thereby moving the valve body 50 of the fuel injection valve 21 to the valve opening position.

[0060] Subsequently, in the holding phase, a low voltage is intermittently applied to the solenoid valve 52 of the fuel injection valve 21 to maintain the drive current around the holding current, which is lower than the pickup current, and thereby hold the valve body 50 of the fuel injection valve 21 in the valve opening position.

[0061] Subsequently, when the injection pulse is turned off, the excitation of the magnet 52 of the fuel injection valve 21 is stopped, thereby closing the valve body 50 of the fuel injection valve 21.

[0062] To cause the injector 21 to inject fuel, it is necessary to allow a larger drive current to flow in the solenoid valve 52 because the fuel pressure supplied to the injector 21 becomes higher. Therefore, in a case where the fuel supply pressure increases excessively due to an abnormality caused in the fuel pump or the like, fuel may not be injected with the fuel injection valve even if the drive current is increased to the target peak current. The case where the fuel supply pressure increases excessively can be considered as follows. For example, fuel injection is performed after deadlock to stop the engine 11 when the engine 11 is at a high temperature. Fuel injection is performed after a hybrid vehicle configured to travel using motor drive power travels using motor drive power.Fuel injection occurs after fuel conservation during a long downhill ride. In short, if the fuel flow (circulation) to the fuel injection valve 21 is stopped while the engine 11 is at a high temperature, the supplied fuel pressure may increase excessively.

[0063] Fig. 8 is a timing chart showing the drive current, suction force, and core lift amount in a case where the fuel injection valve 21 is not fully open. In this case, an example is shown where the supplied fuel pressure is excessively increased, and therefore, the required suction force required to start the lift of the needle 41 and maintain the needle 41 at the full lift position is greater than the required suction force when the supplied fuel pressure is normal.

[0064] As shown in the figure, when the drive current starts flowing at time t11, the actual suction force (electromagnetic force) is generated, which attracts the movable core 40 toward the fixed core 38. At time t12, when the actual suction force increases to a core stroke start suction force required for the movable core 40 to start the stroke, the stroke amount of the movable core 40 begins to increase.

[0065] At time t13, when the movable core 40 begins to press the collar portion 42 of the needle 41, the suction force required to lift the needle 41 to the full lift position increases. When the lift amount of the movable core 40 is greater than the needle closing position, the lift amount of the movable core 40 and the lift amount of the needle 41 substantially coincide.

[0066] After time t13, the actual suction force is less than the required suction force. Therefore, at time t14, the needle 41 returns to the valve-closed position before being raised to the full-lift position. This means that to raise the needle 41 to the full-lift position, the actual suction force must be increased to a level greater than the required suction force until the position of the needle 41 reaches the full-lift position.

[0067] Fig. Fig. 9 is a timing chart showing the driving current, suction force, and core lift amount when the fuel injection valve 21 is not fully opened and unstable. Here, as in Fig. 8, an example is shown where the fuel supply pressure is excessively increased.

[0068] As shown in the figure, from time t22 to time t23, the actual suction force is greater than the required suction force. Therefore, at time t23, the needle 41 is raised to the full-lift position. When the needle 41 is raised to the full-lift position, the movable core 40 collides with the plug 55 and rebounds. Therefore, to stabilize the fuel injection valve 21 in the valve-open state, it is necessary to increase the actual suction force so that it is greater than a stable valve-open suction force by time t24.

[0069] On the contrary, after time t23, the actual suction force is smaller than the stable suction force when the valve is open. Therefore, the fuel injection valve 21 cannot be stabilized in the open state, and even though the needle 41 is raised to the full-lift position, the needle 41 cannot be maintained in the full-lift position.

[0070] Fig. Figure 10 is a timing chart showing the drive current, suction force, and core lift amount when the fuel injection valve 21 is fully opened and stabilized with a single-peak drive current. Here, as shown in Fig. 8, an example is shown where the fuel supply pressure is excessively increased.

[0071] As shown in the figure, after the actual suction force becomes greater than the core lift starting suction force at time t32, the actual suction force becomes greater than the required suction force until time t33. Specifically, the actual suction force is maintained in a state where it is greater than the stable valve-open suction force. Therefore, the needle 41 is lifted to the full-lift position and thereafter maintained in the full-lift position. That is, the fuel injection valve 21 is stabilized in the open state.

[0072] After time t33, the actual suction force is greater than a valve-open holding suction force required to hold the needle 41 in the full-lift position after the needle 41 has been raised to the full-lift position. Therefore, the needle 41 is held in the full-lift position while suppressing the power consumption of the solenoid 52. However, in order to increase the actual suction force with such a single-peak current pattern (singular peak current) greater than the required suction force, it is necessary to significantly increase the target peak current.

[0073] In contrast, Fig. 11 is a timing chart showing the drive current, suction force, and core lift amount when the fuel injection valve 21 is fully opened and stabilized with a multi-peak drive current. Here, as in Fig. 8, an example is shown where the fuel supply pressure is excessively increased.

[0074] As shown in the figure, after the actual suction force becomes greater than the core lift starting suction force at time t42, the actual suction force becomes greater than the required suction force until time t43. Specifically, the actual suction force is maintained in a state where it is greater than the stable valve-open suction force. Therefore, the needle 41 is lifted to the full-lift position and thereafter maintained in the full-lift position. That is, the fuel injection valve 21 is stabilized in the open state.

[0075] After time t43, the actual suction force is greater than the valve-opening holding suction force required to hold the needle 41 in the full-lift position after the needle 41 is lifted to the full-lift position. Therefore, the needle 41 is held in the full-lift position while suppressing the power consumption of the solenoid 52. Furthermore, the actual suction force is increased to be greater than the required suction force, and the current pattern has multiple peaks (continuous peaks), so it is not necessary to increase the target peak current so much.

[0076] Fig. Fig. 12 is a timing chart showing the drive current, suction force, and core lift amount when the fuel injection valve 21 is fully opened and stabilized with a drive current that is increased in slope before several peaks. Here, as in Fig. 8, an example is shown where the fuel supply pressure is excessively increased.

[0077] At the drive current indicated by the dashed line in the figure, the actual attraction force is smaller than the required attraction force at time t53. Therefore, even if the actual suction force is increased to be greater than the required suction force thereafter, the needle 41 cannot be lifted to the full-lift position, or the needle 41 cannot be maintained in the full-lift position.

[0078] In contrast, with the drive current shown by the solid line, where the slope is large as the drive current increases, the actual suction force is not less than the required suction force after time t52. Therefore, the needle 41 can be maintained at the full-lift position after the needle 41 is lifted to the full-lift position. In this way, the slope is increased as the drive current increases, so that the actual suction force does not become less than the required suction force as the drive current increases.

[0079] Fig. Figure 13 is a timing chart showing an example of a drive current pattern (second current pattern) set when the fuel supply pressure is abnormally high. This shows an example where the precharge phase and pickup phase of the drive current are omitted. A pattern P0 (dashed line) shows a single-peak drive current pattern (first current pattern) when the fuel supply pressure is normal. The pattern P0 includes hold control, in which the drive current is increased to the target peak current (maximum value in the injection period) and then continuously decreased to the hold current (hold value).

[0080] In a pattern P1, the target peak current in the single-peak drive current is set to be greater than the target peak current of pattern P0. The target peak current is the maximum value of the drive current in one injection period from the opening of the fuel injection valve 21 to the closing of the fuel injection valve 21. The target peak current of pattern P1 is set to be greater than the upper limit of the target peak current of pattern P0, that is, the upper limit of the target peak current set at normal fuel supply pressure.

[0081] In a P2 pattern, the target peak current in the multiple control current peak is set to be larger than the target peak current of the P0 pattern. The P2 pattern includes peak hold control and hold control. The peak hold control continuously maintains the drive current after the drive current is increased to the target peak current (maximum value in the injection period). The hold control reduces the drive current from the target peak current to the hold current and maintains the drive current. The target peak current of the P2 pattern is set to be larger than the upper limit of the target peak current of the P0 pattern, that is, the upper limit of the target peak current set at normal fuel supply pressure.

[0082] In a P3 pattern, the target peak current in the multiple control current peak is set to be smaller than the target peak current of the P0 pattern. The P3 pattern includes peak hold control and hold control. The peak hold control continuously maintains the drive current after the drive current is increased to the target peak current. The hold control reduces the drive current from the target peak current to the hold current and maintains the drive current. The target peak current of the P3 pattern is set to be smaller than the upper limit of the target peak current of the P0 pattern, that is, the upper limit of the target peak current set at normal fuel supply pressure. It should be noted that, as in Fig. 11, the drive current of pattern P3 is adjusted so that the actual attraction force is greater than the required attraction force.

[0083] In a pattern P4, the inclination at the multiple current control peak when the drive current increases is set to be larger than the inclination when the drive current increases in pattern P0. Specifically, the voltage applied to the solenoid 52 when the drive current is increased to the target peak current is set to be larger than the voltage applied to the solenoid 52 in pattern P0 when the drive current is increased to the target peak current. The inclination of pattern P4 when the drive current increases is set to be larger than the upper limit of the inclination of pattern P0 when the drive current increases, that is, the upper limit of the inclination when the drive current increases, which is set at normal fuel supply pressure. Pattern P4 is an example in which the control for increasing the inclination when the drive current increases is applied to pattern P2.The control for increasing the inclination with increasing drive current can be applied not only to the P2 pattern, but also to the P0, P1 and P3 patterns.

[0084] Furthermore, in patterns P1 to P4, control may be performed to maintain the drive current at the pickup current before maintaining the drive current at the holding current, after increasing the drive current to the target peak current, or after increasing the drive current to the target peak current and maintaining the target peak current. All of the above controls, including these modified examples, correspond to the second drive current pattern, which is set when the fuel supply pressure is abnormally high.

[0085] Fig. 14 is a schematic diagram showing examples of combinations of the peak shape of the drive current, the presence / absence of the pickup control, and the magnitude of the drive voltage.

[0086] As shown in the figure, the ECU 60 is configured to select a single-peak or multi-peak as the peak shape of the drive current. The high voltage supplied by the boost current source 65 is used as the drive voltage when the drive current is increased to the target peak current.

[0087] As a pickup control, the ECU 60 is configured to select whether pickup control is performed. The battery voltage (low voltage) supplied by the low-voltage power supply 64 and the boost voltage (high voltage) supplied by the boost power supply 65 can be selected as the drive voltage when the pickup control is performed.

[0088] In the hold control, the ECU 60 maintains the drive current at the hold current using the battery voltage supplied by the low voltage power supply 64.

[0089] In this way, the ECU 60 sets the second current pattern by combining the peak shape of the drive current, the presence or absence of the pickup control, and the level of the drive voltage.

[0090] Fig. Figure 15 is a flowchart showing a flow of drive current control. This series of processes is repeatedly executed by the ECU 60.

[0091] First, it is determined whether the fuel pressure sensor 57 is normal or not (S10). For example, it is determined whether a value of the supplied fuel pressure detected by the fuel pressure sensor 57 is within a range of a normal value. If, in this determination, it is determined that the fuel pressure sensor 57 is abnormal (S10: NO), the drive current is set to the first current pattern (S17). The first current pattern (first mode) is a pattern of a drive current that flows through the solenoid valve 52 of the fuel injection valve 21 when the fuel supply pressure is within the normal value range. Subsequently, the drive current is controlled with the first current pattern (e.g., the pattern P0 in Fig. 13), and the fuel is injected using the fuel injection valve 21 (S18). The process is then terminated (END).

[0092] On the contrary, if it is determined in the determination of S10 that the fuel pressure sensor 57 is normal (S10: YES), it is determined whether or not the fuel supply pressure detected with the fuel pressure sensor 57 is higher than a determination pressure (S11). The determination pressure is a pressure for determining that the fuel supply pressure is abnormally high and is a pressure that cannot occur under normal conditions. As the determination pressure, for example, a pressure at which the fuel injection valve 21 cannot be fully opened when the drive current is controlled with the first current pattern is assumed. When this determination pressure is applied and the movable core 40 collides against the collar part 42 of the needle 41, the needle 41 can be lifted to a position before the full lift position.When determining that the fuel supply pressure detected by the fuel pressure sensor 57 is not higher than the determination pressure (S11: NO), processing proceeds to S17. In the process of S11, it can be determined whether the fuel supply pressure is equal to or higher than the determination pressure.

[0093] On the contrary, in the determination of S11, if it is determined that the fuel supply pressure detected by the fuel pressure sensor 57 is higher than the determination pressure (S11: YES), the drive current is set to the second current pattern (S12). For example, it is set so that each of the patterns P1 to P4 in Fig. 13 by one of the combinations in Fig. 14 is formed. The higher the speed of the engine 11, the shorter the interval between fuel injection and injection. Therefore, in the case of the multiple current control peak, the heat generated by the ECU 60 tends to accumulate when the drive current is maintained at the target peak current. Therefore, the temperature of the ECU 60 may exceed its heat-resistant temperature. Therefore, in the second current pattern, the period in which the drive current is maintained after increasing to the target peak current (see the peak duration Tp in Fig. 16) is maintained continuously, is set shorter with increasing speed of the motor 11.

[0094] A permanent protection value Tcg is then set (S13). As shown in Fig. As shown in Figure 16, the continuous protection value Tcg (predetermined period) is an upper limit of a period during which the fuel injection valve 21 can be continuously driven with the second current pattern when fuel injections are continuously performed using the multiple injection valves 21. That is, the continuous protection value Tcg is an upper limit of the period during which the drive current can be continuously controlled with the second current pattern. As shown in Fig. As shown in Figure 17, the continuous protection value Tcg is set shorter as the speed NE of motor 11 increases. If the speed NE of motor 11 is higher than a preset speed NE1, the continuous protection value Tcg is set to 0. This means that if the speed NE of motor 11 is higher than the preset speed NE1, the drive current is not adjusted using the second current pattern, but the drive current is adjusted using the first current pattern. The diagram in Fig. 17 can be adjusted according to the heat-resistant temperature of the ECU 60.

[0095] Subsequently, an elapsed time protection value Ing from the previous instance is set (S14). As in Fig. 16, the elapsed time protection value Ing is a lower limit of a period ranging from the time at which the fuel injections of the plurality of fuel injection valves 21 with the second current pattern are stopped to the time at which the fuel injections of the plurality of fuel injection valves 21 with the second current pattern can be started. As shown in Fig. As shown in Figure 18, if the previous duration of fuel injection with the second current pattern becomes longer, the elapsed time protection value Ing is set longer. The diagram in Fig. 18 can be set according to the heat resistance temperature of the ECU 60.

[0096] Subsequently, the drive current is controlled with the second current pattern, and the fuel is injected by means of the fuel injection valve 21 (S15).

[0097] Subsequently, it is determined whether the guard with the continuous protection value Tcg or the guard with the elapsed time protection value Ing is being performed (S16). If it is determined in this determination that neither the protection with the continuous protection value Tcg nor the protection with the elapsed time protection value Ing is being performed (S16: NO), the processing from the process of S13 is executed again. That is, in a case where the duration of the fuel injections of the plurality of fuel injection valves 21 with the second current pattern is shorter than the continuous protection value Tcg and the elapsed time from the end of the previous fuel injection with the second current pattern is longer than the elapsed time protection value Ing, the processing from the process of S13 is executed again.

[0098] In contrast, in the determination of S16, if it is determined that the protection with the continuous protection value Tcg or the protection with the elapsed time protection value Ing is being performed (S16: YES), the processing proceeds to S17. That is, in a case where the duration of the fuel injections of the plurality of fuel injection valves 21 with the second current pattern is longer than the continuous protection value Tcg, or where the elapsed time from the end of the previous fuel injection with the second current pattern is shorter than the elapsed time protection value Ing, the processing proceeds to S17. Subsequently, the drive current is set to the first current pattern (S17), fuel with the first current pattern is injected via the fuel injection valve 21 (S18), and this processing (series) is completed (END).

[0099] The sequence of S11 corresponds to a process of a determination unit. The process of S17 corresponds to the process or method of a first control unit. The process of S12 corresponds to the process or method of a second control unit.

[0100] The present embodiment described in detail above has the following advantages.

[0101] -It is determined whether the fuel supply pressure, that is, the pressure of the fuel supplied to the fuel injection valve 21, is higher than the determination pressure to determine whether the fuel pressure is abnormally high or not. Moreover, in a case where it is determined that the fuel supply pressure is not higher than the determination pressure, the drive current is controlled with the first current pattern. Alternatively, in a case where it is determined that the fuel supply pressure is higher than the determination pressure, the drive current is controlled with the second current pattern, which makes it easier to maintain the open state of the fuel injection valve 21 compared to the first current pattern. Therefore, even if the fuel supply pressure is higher than the determination pressure, the configuration allows the fuel injection valve 21 to perform fuel injection.

[0102] -The power consumption of the second current pattern is greater than the power consumption of the first current pattern. Therefore, when the fuel supply pressure is not higher than the target pressure, i.e., when the fuel supply pressure is normal, the drive current is controlled using the first current pattern. Therefore, this configuration allows for suppression of an increase in power consumption.

[0103] The target pressure is the pressure at which the fuel injection valve 21 cannot be fully opened when the drive current is controlled with the first current pattern. Therefore, the fuel injection valve 21 cannot be fully opened when the fuel supply pressure becomes higher than the target pressure and the drive current is controlled with the first current pattern. In this case, the configuration controls the drive current with the second current pattern, thereby enabling the fuel injection valve 21 to fully open for fuel injection.

[0104] -In the fuel injection valve 21 with the core boost structure, the drive current required to move the movable core 40 and the needle 41 becomes larger than the drive current required to move only the movable core 40. Therefore, the valve body 50 can be moved to the fully open position only when the drive current when the movable core 40 and the needle 41 are moved is larger than the predetermined current. In this regard, in the pattern P4 in Fig. 13, the voltage applied to the solenoid 52 when the drive current is increased to the target peak current is set to be greater than the voltage applied to the solenoid 52 in pattern P0 when the drive current is increased to the target peak current. Therefore, the configuration makes it possible to increase the drive current when the needle 41 is moved to be greater than the predetermined current. Therefore, the configuration makes it possible to cause the fuel injection valve 21 to inject fuel at a higher fuel supply pressure.

[0105] The patterns P2 and P3 in Fig. 13 include peak hold control and hold control. Peak hold control continuously maintains the drive current after the drive current is increased to the target peak current. Hold control reduces the drive current from the target peak current to the holding current and maintains the drive current. In peak hold control, the drive current is increased to the target peak current and then continuously held. Therefore, the configuration enables the continuous maintenance of the electromagnetic force generated by the use of the solenoid coil 52 after the electromagnetic force is increased to the maximum value. In addition, the configuration makes it possible to facilitate the opening of the fuel injection valve 21 and to keep the fuel injection valve 21 in the open state. In addition, the configuration reduces the drive current from the target peak current to the holding current and holds the drive current.Therefore, the configuration enables suppression of power consumption when the fuel injection valve 21 is kept in the open state.

[0106] In pattern P0 in Fig. 13, the drive current is increased to the target peak current and then continuously decreased to the holding current and maintained. In contrast, in pattern P2, the drive current is maintained at the target peak current, which is greater than the target peak current of the drive current in pattern P0. Therefore, the configuration makes it easier to maintain the fuel injection valve 21 in the open state with pattern P2 compared to pattern P0.

[0107] In pattern P3 in Fig. 13, the drive current is maintained at the target peak current, which is smaller than the target peak current of the drive current in pattern P0. That is, as in Fig. 9 and Fig. As shown in Figure 11, even in a case where the target peak current of the drive current in pattern P3 is smaller than the target peak current of the drive current in pattern P0, the configuration continues to maintain the drive current after increasing the drive current to the target peak current, thereby facilitating the maintenance of the fuel injection valve 21 in the open state. Therefore, the configuration makes it easier to maintain the fuel injection valve 21 in the open state and suppresses an increase in current consumption.

[0108] -With the ECU 60, the period for maintaining the drive current after increasing the drive current to the target peak current is set to be shorter as the speed of the motor 11 increases. This configuration therefore makes it possible to prevent the temperature of the ECU 60 from exceeding the heat-resistant temperature even as the speed of the motor 11 increases. The period for maintaining the drive current at the target peak current can be set by time or by crank angle.

[0109] -If the period for which the drive current is continuously controlled with the second current pattern becomes too long, the temperature of the ECU 60 may exceed the heat-resistant temperature. In this regard, when the period for which the drive current is continuously controlled with the second current pattern becomes longer than the continuous protection value Tcg, the ECU 60 switches the drive current with the second current pattern to the drive current with the first current pattern. Therefore, when the temperature of the ECU 60 rises due to the continuous control of the drive current with the second current pattern, the ECU 60 switches the drive current to the first current pattern, so that the temperature rise of the ECU 60 can be suppressed. The period for which the drive current is continuously controlled with the second current pattern and the continuous protection value Tcg can be specified by time or by the crank angle.

[0110] The above-described embodiment may be modified as follows. Elements identical to those of the above embodiment are denoted by the same reference numerals as the above embodiment, and redundant descriptions thereof are omitted.

[0111] The ECU 60 may set the determination pressure to a pressure at which fuel injection cannot be performed using the fuel injection valve 21 when the drive current is controlled with the first current pattern (first mode). Particularly in an electromagnetically driven fuel injection valve that does not have the core boost structure, the fuel injection valve 21 tends to be unable to inject fuel when the fuel supply pressure becomes abnormally high.

[0112] According to the configuration described above, the fuel injection valve 21 cannot inject fuel when the fuel supply pressure becomes higher than the target pressure and when the drive current is controlled with the first current pattern. In this case, the configuration controls the drive current with the second current pattern (second mode), thereby allowing the fuel injection valve 21 to inject fuel.

[0113] -A high-voltage battery, whose voltage is higher than the voltage of the 12V battery, can be used instead of the boost power supply 65. In addition, the boost voltage can be applied by increasing the generated voltage of the generator, which applies the voltage to the fuel injector 21.

[0114] The ECU 60 can be a Fig. 19 as the first current pattern (first mode). This first current pattern includes a control for applying a voltage Vm to the solenoid 52 in the direction to reduce the drive current after increasing the drive current to the target peak current (maximum value in the injection period). This configuration makes it possible to suppress noise generated when the fuel injection valve 21 is fully open.

[0115] In contrast, the second current pattern (second mode) does not include the control for applying the voltage Vm to the solenoid 52 in the direction to reduce the drive current after increasing the drive current to the target peak current. Therefore, in the case where the drive current is controlled with the second current pattern, the voltage Vm is not applied to the solenoid 52 in the direction to reduce the drive current after increasing the drive current to the target peak current. Therefore, when the fuel supply pressure increases excessively, the configuration makes it possible to give priority to the ease of maintaining the open state of the fuel injection valve 21 over the suppression of noise. In the patterns P2 and P3 in Fig. 13, after completion of the peak hold control for maintaining the drive current at the target peak current, the control for applying the voltage Vm to the magnet 52 in the direction of reducing the drive current can be performed.

[0116] The ECU 60 (second control unit) can set the time for continuously maintaining the drive current after increasing the drive current to the target peak current until the fuel injection valve 21 stabilizes in the open state. This configuration makes it possible to increase the drive current to the target peak current and then maintain the drive current at the target peak current until the fuel injection valve 21 stabilizes in the open state when the drive current is controlled with the second current pattern. Therefore, with this configuration, it is possible to achieve stable fuel injection by the fuel injection valve 21 even when the fuel supply pressure increases excessively. The time until the fuel injection valve 21 stabilizes in the open state can be determined in advance based on an experiment or the like.The time it takes for the valve to stabilize in the open state can be specified by time or crank angle.

[0117] -In Fig. 15, the ECU 60 can make the same determination as in S11 between the process of S15 and the process of S16. In this determination, if it is determined that the fuel supply pressure detected by the fuel pressure sensor 57 is not higher than the determination pressure, the processing proceeds to S17. If it is determined that the fuel supply pressure is higher than the determination pressure, the processing proceeds to S16. That is, the ECU 60 (second control unit) can switch the drive current with the second current pattern to the drive current with the first current pattern when the fuel supply pressure becomes equal to or lower than the determination pressure. This configuration makes it possible to switch the drive current with the second current pattern to the drive current with the first current pattern when the fuel supply pressure becomes equal to or lower than the determination pressure.Therefore, the configuration enables suppressing the control of the drive current with the second current pattern more than necessary to suppress the temperature rise of the ECU 60 and the increase in power consumption.

[0118] Furthermore, a pressure relief valve may be provided on a delivery line intended to supply fuel to the fuel injection valve 21. As shown in Fig.As shown in Figure 20, the relief valve opens to reduce the fuel pressure in the delivery line when the fuel pressure in the delivery line becomes higher than a relief pressure. In this configuration, in a case where the fuel supply pressure becomes higher than the designation pressure and the drive current is controlled with the second current pattern, the relief valve opens when the fuel pressure in the delivery line becomes higher than the relief pressure. The configuration switches the drive current with the second current pattern to the drive current with the first current pattern when the fuel supply pressure consequently becomes lower than the designation pressure. In addition, if the fuel supply pressure does not drop below the designation pressure immediately after the relief or relief valve opens, the configuration controls the drive current with the second current pattern until the fuel supply pressure becomes lower than the designation pressure.

Claims

[1] A control device (60) configured to control a drive current flowing through a drive coil (52) of a fuel injection valve (21) configured to be electromagnetically driven, the control device comprising: a determination unit configured to determine whether a fuel supply pressure, which is a pressure of the fuel supplied to the fuel injection valve, is higher than a determination pressure at which the fuel pressure is determined to be abnormally high; a first control unit configured to control the drive current in a first mode when the determining unit determines that the fuel supply pressure is not higher than the determination pressure; and a second control unit configured to control the drive current in a second mode that allows the fuel injection valve to be kept in an open state more than in the first mode when the determining unit determines that the fuel supply pressure is higher than the determining pressure, wherein a voltage applied to the drive coil when the drive current is increased to a maximum value in an injection period in the second operating mode is higher than a voltage applied to the drive coil when the drive current is increased to a maximum value in an injection period in the first operating mode. [2] A control device for the fuel injection valve according to claim 1, wherein the second mode comprises control for continuously maintaining the drive current after increasing the drive current to a maximum value in an injection period, and control for reducing the drive current from the maximum value in the injection period to a holding value and maintaining the drive current. [3] A control device for the fuel injection valve according to claim 2, wherein the first mode comprises a control to increase the drive current to the maximum value during the injection period and then continuously reduce the drive current to the holding value and maintain the drive current, and the maximum value of the drive current in the injection period in the second mode is greater than the maximum value of the drive current in the injection period in the first mode. [4] A control device (60) configured to control a drive current flowing through a drive coil (52) of a fuel injection valve (21) configured to be electromagnetically driven, the control device comprising: a determination unit configured to determine whether a fuel supply pressure, which is a pressure of the fuel supplied to the fuel injection valve, is higher than a determination pressure at which the fuel pressure is determined to be abnormally high; a first control unit configured to control the drive current in a first mode when the determining unit determines that the fuel supply pressure is not higher than the determination pressure; and a second control unit configured to control the drive current in a second mode that allows the fuel injection valve to be kept in an open state more than in the first mode when the determining unit determines that the fuel supply pressure is higher than the determining pressure, wherein the second mode comprises a control for continuously maintaining the drive current after increasing the drive current to a maximum value in an injection period and a control for reducing the drive current from the maximum value in the injection period to a holding value and for maintaining the drive current, wherein the first mode comprises a control to increase the drive current to the maximum value during the injection period and then continuously reduce the drive current to the holding value and maintain the drive current, and the maximum value of the drive current in the injection period in the second mode is greater than the maximum value of the drive current in the injection period in the first mode. [5] A control device for the fuel injection valve according to claim 2, wherein the first mode comprises a control to increase the drive current to the maximum value during the injection period and then continuously reduce the drive current to the holding value and maintain the drive current, and the maximum value of the drive current in the injection period in the second mode is smaller than the maximum value of the drive current in the injection period in the first mode. [6] A control device (60) configured to control a drive current flowing through a drive coil (52) of a fuel injection valve (21) configured to be electromagnetically driven, the control device comprising: a determination unit configured to determine whether a fuel supply pressure, which is a pressure of the fuel supplied to the fuel injection valve, is higher than a determination pressure at which the fuel pressure is determined to be abnormally high; a first control unit configured to control the drive current in a first mode when the determining unit determines that the fuel supply pressure is not higher than the determination pressure; and a second control unit configured to control the drive current in a second mode that allows the fuel injection valve to be kept in an open state more than in the first mode when the determining unit determines that the fuel supply pressure is higher than the determining pressure, wherein the second mode comprises a control for continuously maintaining the drive current after increasing the drive current to a maximum value in an injection period and a control for reducing the drive current from the maximum value in the injection period to a holding value and for maintaining the drive current, wherein the first mode comprises a control to increase the drive current to the maximum value during the injection period and then continuously reduce the drive current to the holding value and maintain the drive current, and the maximum value of the drive current in the injection period in the second mode is smaller than the maximum value of the drive current in the injection period in the first mode. [7] A control device for the fuel injection valve according to any one of claims 2 to 6, wherein the second control unit is configured to set a period in which the second control unit continuously maintains the drive current after increasing the drive current to the maximum value in the injection period, so that the period becomes shorter as a rotational speed of the engine (11) on which the fuel injection valve is mounted becomes higher. [8] The control device for the fuel injection valve according to any one of claims 2 to 6, wherein the second control unit is configured to set a period in which the second control unit continuously maintains the drive current after increasing the drive current to the maximum value in the injection period to a period in which the fuel injection valve is stabilized in the open state. [9] The control device for the fuel injection valve according to any one of claims 1 to 8, wherein the second control unit is configured to change the drive current in the second mode to the drive current in the first mode when the period in which the second control unit continuously controls the drive current in the second mode becomes longer than a predetermined period. [10] A control device (60) configured to control a drive current flowing through a drive coil (52) of a fuel injection valve (21) configured to be electromagnetically driven, the control device comprising: a determination unit configured to determine whether a fuel supply pressure, which is a pressure of the fuel supplied to the fuel injection valve, is higher than a determination pressure at which the fuel pressure is determined to be abnormally high; a first control unit configured to control the drive current in a first mode when the determining unit determines that the fuel supply pressure is not higher than the determination pressure; and a second control unit configured to control the drive current in a second mode that allows the fuel injection valve to be kept in an open state more than in the first mode when the determining unit determines that the fuel supply pressure is higher than the determining pressure, wherein the second control unit is configured to change the drive current in the second mode to the drive current in the first mode when the period in which the second control unit continuously controls the drive current in the second mode becomes longer than a predetermined period. [11] A control device for the fuel injection valve according to any one of claims 1 to 8, wherein the second control unit is configured to change the drive current in the second mode to the drive current in the first mode when the fuel supply pressure becomes equal to or lower than the determination pressure. [12] Control device for the fuel injection valve according to one of claims 1 to 11, wherein the first mode comprises a control for applying a voltage in a direction to reduce the drive current to the drive coil after the drive current has been increased to a maximum value in an injection period, and the second mode does not include the control of applying the voltage in the direction of reducing the drive current to the drive coil after the drive current has been increased to a maximum value in an injection period. [13] A control device (60) configured to control a drive current flowing through a drive coil (52) of a fuel injection valve (21) configured to be electromagnetically driven, the control device comprising: a determination unit configured to determine whether a fuel supply pressure, which is a pressure of the fuel supplied to the fuel injection valve, is higher than a determination pressure at which the fuel pressure is determined to be abnormally high; a first control unit configured to control the drive current in a first mode when the determining unit determines that the fuel supply pressure is not higher than the determination pressure; and a second control unit configured to control the drive current in a second mode that allows the fuel injection valve to be kept in an open state more than in the first mode when the determining unit determines that the fuel supply pressure is higher than the determining pressure, wherein the first mode comprises a control for applying a voltage in a direction to reduce the drive current to the drive coil after the drive current has been increased to a maximum value in an injection period, and the second mode does not include the control of applying the voltage in the direction of reducing the drive current to the drive coil after the drive current has been increased to a maximum value in an injection period. [14] A control device for the fuel injection valve according to any one of claims 1 to 13, wherein the determination pressure is a pressure at which the fuel injection valve is unable to inject fuel when the drive current is controlled in the first mode. [15] A control device for the fuel injection valve according to any one of claims 1 to 13, wherein the determination pressure is a pressure at which the fuel injection valve is unable to be in a fully open state when the drive current is controlled in the first mode. [16] Fuel injection system, comprising: the fuel injection valve control device according to one of claims 1 to 15; the fuel injection valve; and a fuel pressure sensor (57) configured to detect the fuel supply pressure.

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