Fuel injection valve control device

Abstract

A control device (127) that controls a fuel injection valve (105) that includes a variable lift mechanism that varies a lift amount of a valve body (303) through a drive stroke of two or more stages, wherein the control device (127) for a fuel injection valve (105) detects the inflection point from a drive voltage during a valve closing operation of the fuel injection valve (105) or from a drive current during a valve opening operation and determines that the drive stroke is larger as the number of detected inflection points is larger.

Description

Technical area

[0001] The present invention relates to a control device for a fuel injection valve that injects fuel into an internal combustion engine and supplies fuel to an internal combustion engine. Technical background

[0002] The recent increase in automotive fuel consumption and exhaust emission regulations require both low fuel consumption and high engine power output, and the engine to be adapted for a wide operating range. One of the means to achieve this is to extend the dynamic range of the fuel injector.

[0003] To expand the dynamic range of the fuel injection valve, it is necessary to improve the dynamic flow characteristics while maintaining the conventional static flow characteristics. Reducing the minimum injection quantity through half-lift control is known as a method for improving the dynamic flow characteristics.

[0004] It is known that this half-lift control performs precision control in a state (hereinafter referred to as a half-lift region) before a valve body provided in the fuel injection valve reaches the valve opening position (hereinafter referred to as a full lift), but the variation in the injection amount in the half-lift region is large due to the individual differences of the fuel injection valves. For this reason, various techniques for sensing the individual differences occurring in each fuel valve have been proposed. For example, PTL 1 discloses a technique for indirectly sensing a single difference in a valve opening operation of a fuel injection valve (specifically, a timing at which a valve body is in an open state of the valve) based on the electrical characteristics.Similarly, it is also a known technique to sense a valve closing operation of the fuel injector based on the electrical characteristics.

[0005] In addition, as a technique for expanding the dynamic range of a fuel injection valve, PTL 2 discloses a fuel injection valve that changes an injection amount (an injection speed) per unit time by changing a lift amount of the valve body by two movable cores. The fuel injection valve can inject fuel at a full lift in the conventional half-lift range, thereby enhancing the accuracy of the injection amount at the time of injecting a small amount. It is further disclosed as such a control method that the lift amount is variable depending on a magnitude of a drive current flowing through the fuel injection valve. Furthermore, US 10 240 551 B2 (refer to PTL 3) discloses an electromagnetic valve control unit for controlling the opening / closing of the valve body.Closing an electromagnetic valve by applying a control voltage and / or a control current, wherein the control unit for an electromagnetic valve is configured to correct the control voltage and / or the control current applied to the electromagnetic valve based on a detection time of an inflection point from time series data of the control voltage digitized by an A / D converter and / or the control current digitized by an A / D converter when the electromagnetic valve is opened or closed, wherein the control unit uses, among other things, a reference pattern having the same characteristics as a high-pass extraction filter for this purpose. DE 10 2005 004 442 A1 (cf. PTL 4) discloses a method for controlling an internal combustion engine which, due to its special configuration, enables low-emission operation of the internal combustion engine.DE 102 33 778 A1 (cf. PTL 5) discloses a method for compensating torque differences between the cylinders of an internal combustion engine, in which an improvement in the smooth running of the internal combustion engine is achieved without changing the injection duration. Finally, DE 11 2014 004 658 B4 (cf. PTL 6) discloses a fuel injection control system of an internal combustion engine with an electromagnetically driven fuel injection valve, wherein a difference calculation means, a time calculation means, and an injection pulse correction means are provided, the latter correcting an injection pulse of a partial stroke injection based on a voltage turnaround time. List of citationsPatent literature PTL 1: JP 2014 - 152 697 A PTL 2: JP 2006 - 132 412 A PTL 3: US 10 240 551 B2 PTL 4: DE 10 2005 004 442 A1 PTL 5: DE 102 33 778 A1 PTL 6: DE 11 2014 004 658 B4 Summary of the inventionTechnical problem

[0006] However, a current value for controlling the lift amount of the fuel injection valve varies with respect to the commanded current value due to the influence of a variation in the working difference between the fuel injection valve and the fuel injection control device that controls the fuel injection valve. Furthermore, because the valve-opening operation of the fuel injection valve is subject to the influence of fuel pressure, it is necessary to change the current value according to the fuel pressure value to control the lift amount. This fuel pressure value is generally measured using a fuel pressure sensor. However, because pulsation occurs in a common fuel rail to which the fuel pressure sensor is attached, it is difficult to measure an accurate fuel pressure value at the time of fuel injection.

[0007] Therefore, there is a possibility that the current value flowing through the fuel injection valve varies due to the variation in the working difference, the fluctuation in the fuel pressure and the like described above, and the fuel injection valve operates with a lift amount different from the designed lift amount (ie, a command drive stroke instructed to the fuel injection valve in accordance with the operating state of the internal combustion engine and the like) to inject fuel.

[0008] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a control device for a fuel injection valve that can accurately monitor the lift amount (actual lift amount) of the fuel injection valve having the variable lift mechanism described above and suppress the deterioration of exhaust emissions and unintended torque fluctuations due to the deviation between the lift amount and the design lift amount. Solution to the problem

[0009] The problem is solved by the features of claims 1, 2, 8, and 9. Particular embodiments are described in the dependent claims. Advantageous effects of the invention

[0010] According to the control device for a fuel injection valve according to the present invention, in the fuel injection valve including a variable lift mechanism that varies the lift amount by a multi-stage drive stroke, it is possible to avoid significant deterioration of exhaust emission and unintended torque fluctuations because the lift amount (the actual drive stroke) of the fuel injection valve can be accurately sensed even when the fuel injection valve is driven at a lift amount different from the intended lift amount (the command drive stroke) due to a malfunction of the fuel injection valve or the like.

[0011] The objects, configurations and effects other than those described above will be made clear from the description of the embodiments below. Brief description of the drawings Fig. 1 is an overall configuration diagram showing an example of a basic configuration of an internal combustion engine equipped with a fuel injection valve control device (a fuel injection control device) according to the present invention. Fig. 2 is a graphical representation of the basic configuration, which Fig. 1 shows the fuel injection control device. Fig. 3 is a schematic diagram of the main parts showing a structural example and an operation example of the Fig. 1 shows the fuel injector. Fig. 4 is a graph for explaining a basic operation (a deep lift) of the fuel injection valve. Fig. 5 is a diagram for explaining a basic operation (high lift) of the fuel injection valve. Fig. Figure 6 is a graph showing the Ti-Q characteristics of the fuel injector. Fig. 7 is a graph for explaining a relationship between a command drive current and an actual drive current. Fig. 8 is a graphical representation for explaining a turning point at the time of deep stroke driving. Fig. 9 is a graphical representation for explaining an inflection point at the time of high-lift driving. Fig. 10 is a flowchart for explaining a control flow of sensing the actual drive stroke and a drive stroke limitation by the Fig. 1 shown fuel injection control device. Fig. 11 is a graph showing an example of the time series data of a driving voltage during a valve closing operation at the time of high lift driving and its second-order differential value. Fig. 12 is a graph showing an example of the time series data of a driving voltage during a valve closing operation at the time of deep lift driving and its second-order differential value. Fig. 13 is a graph showing an example of the time series data of a drive current during a valve opening operation at the time of high lift driving and its second-order differential value. Fig. 14 is a graph showing an example of the time series data of a drive current during a valve opening operation at the time of deep lift driving and its second-order differential value. Fig. 15 is a graphical representation for explaining the sampling of the actual drive stroke based on the number of inflection points. Fig. 16 is a graph for explaining the sampling of the actual drive stroke based on the time to an inflection point. Fig. Fig. 17 is a graph for explaining the sampling of the actual drive stroke based on the magnitude of an extreme value at an inflection point. Fig. 18 is a graphical representation for explaining the sampling of the actual drive stroke based on the patterns of the inflection points. Description of the embodiments

[0012] Hereinafter, the embodiments of a control device for a fuel injection valve (a fuel injection control device) according to the present invention will be described with reference to the drawings.

[0013] In the present embodiment, a form is described in which an electromagnetic fuel injection valve that injects fuel into a combustion chamber of the internal combustion engine and includes a variable lift mechanism that varies a lift amount of the valve body through a drive stroke of two stages (a high lift and a low lift) is adopted as a fuel injection valve, and the fuel injection control device is used as a control device of an internal combustion engine, but needless to say, an appropriate valve that is electromagnetically driven and includes a variable lift mechanism that can vary the lift amount of the valve body through a drive stroke of multiple stages (e.g., three or more stages) may be adopted as the fuel injection valve.

[0014] Fig. 1 shows an example of a basic configuration of an internal combustion engine equipped with a fuel injection valve control device (a fuel injection control device) according to the present invention.

[0015] In Fig. 1, the air taken into an internal combustion engine 101 (the intake air) passes through an air flow meter 120, is taken in in the order of a throttle valve 119 and a manifold 115, and is then supplied into a combustion chamber 121 through an intake pipe 110 and an intake valve 103 provided on each cylinder.

[0016] Meanwhile, fuel is supplied from a fuel tank 123 to a high-pressure fuel pump 125 provided in the internal combustion engine 101 through a low-pressure fuel pump 124. The high-pressure fuel pump 125 reciprocates a plunger provided in the high-pressure fuel pump 125 by the power transmitted from an exhaust camshaft (not shown) provided on an exhaust cam 128 to pressurize the fuel in the high-pressure fuel pump 125 (increase the pressure of the fuel in the high-pressure fuel pump 125). Based on a control command value from an ECU 109, an open / close valve provided in an intake passage is controlled with a solenoid so that the pressure of the fuel (the fuel pressure) discharged from the high-pressure fuel pump 125 becomes a target pressure.

[0017] As a result, high-pressure fuel is supplied to a fuel injection valve 105 through a high-pressure fuel line 129, and the fuel injection valve 105 injects the fuel directly into the combustion chamber 121 based on a command from a fuel injection control device 127 provided in the ECU 109.

[0018] Generally, the internal combustion engine 101 includes a fuel pressure sensor 126 for measuring the pressure in the high-pressure fuel line 129 to control the high-pressure fuel pump 125. The ECU 109 performs feedback control based on this sensor value so that the fuel pressure in the high-pressure fuel line 129 becomes a target pressure. Furthermore, the internal combustion engine 101 is configured so that an ignition coil 107 and a spark plug 106 are provided for each combustion chamber 121. The ECU 109 performs energization control of the ignition coil 107 and ignition control by the spark plug 106 with a target timing.

[0019] As a result, an air-fuel mixture in the combustion chamber 121, where the intake air and fuel are mixed, is combusted by the spark emitted by the spark plug 106, and a piston 102 is pushed downward by this pressure. Exhaust gas generated by the combustion is discharged through an exhaust valve 104 to an exhaust pipe 111. A three-way catalyst 112 is provided in the exhaust pipe 111 to purify the exhaust gas.

[0020] The ECU 109 includes the above-described fuel injection control device 127 and receives signals from a crank angle sensor 116 that measures an angle of a crankshaft (not shown) in the internal combustion engine 101, the air flow meter 120 that indicates the intake air amount, an oxygen sensor 113 that measures an oxygen concentration in the exhaust gas, an accelerator pedal opening sensor 122 that indicates a degree of opening of an accelerator pedal operated by a driver, the fuel pressure sensor 126, and the like.

[0021] As further described, the signals input from each sensor are used to calculate the required torque of the engine 101 based on the signal from the accelerator opening sensor 122, and to determine whether the engine is in an idling state. Additionally, the ECU 109 is provided with rotational speed measuring means for calculating the rotational speed of the engine 101 (hereinafter referred to as an engine speed) based on the signals from the crank angle sensor 116, means for determining whether the three-way catalyst 112 is warmed up based on the coolant temperature of the engine 101 obtained from a water temperature sensor 108 and the elapsed time since the engine 101 was started, and the like.

[0022] Further, the ECU 109 calculates an amount of intake air necessary for the internal combustion engine 101 based on the required torque of the above-described internal combustion engine 101, outputs an opening signal in accordance with the amount of intake air to the throttle valve 119, the fuel injection control device 127 calculates a fuel amount in accordance with the amount of intake air, outputs a fuel injection signal corresponding to the fuel amount to the fuel injection valve 105, and further outputs an ignition signal to the ignition coil 107.

[0023] Next, the fuel injection control device 127 of the ECU 109 and the fuel injection valve 105 shown in Fig. 1 are shown, with respect to Fig. 2 described.

[0024] The fuel injection control device 127 essentially includes, as a fuel injection control unit, a fuel injection pulse signal calculation unit 201, a fuel injection drive waveform command unit (a current waveform correction unit) 202, an engine state sampling unit 203, a drive sampling unit 212, an inflection point detection unit 211, a drive IC 208, a high voltage generation unit (a booster) 206, and the fuel injection drive units (the switches) 207a and 207b.

[0025] The engine state sampling unit 203 collects various information such as the engine speed, the amount of intake air, the coolant temperature, the fuel temperature, and a malfunction state of the internal combustion engine (the engine), and provides this various information. The fuel injection pulse signal calculation unit 201 calculates an injection pulse (a width) defining a fuel injection period of the fuel injection valve 105 based on the various information obtained from the engine state sampling unit 203. The fuel injection drive waveform command unit 202 calculates a command value of the drive current supplied to open or maintain the opening of the fuel injection valve 105 and outputs the command value to the drive IC 208.

[0026] The high-voltage generation unit 206 generates a high-power supply voltage (hereinafter referred to as a high voltage) 210 required when the solenoid-type electromagnetic fuel injection valve 105 is opened, using a battery voltage 209 supplied through a fuse 204 and a relay 205 as a source. Further, the high-voltage generation unit 206 increases the battery voltage 209 to a desired target high voltage based on a command from the drive IC 208. As a result, a dual system is provided as a power supply to the fuel injection valve 105, including a high voltage 210 for ensuring a valve-opening force of the valve body and the battery voltage 209 for maintaining the valve open to prevent the valve body from closing after the valve is opened.

[0027] The two fuel injection drive units 207a and 207b are provided on the upstream side and the downstream side of the fuel injection valve 105 and supply a drive current to the fuel injection valve 105. The drive IC 208 controls the high voltage 210 or the battery voltage 209 applied to the fuel injection valve 105 by switching the fuel injection valve drive units 207a and 207b, which are the switches, based on the injection pulse (width) calculated by the fuel injection pulse signal calculation unit 201 and the drive current waveform calculated by the fuel injection drive waveform command unit 202, to control the drive current supplied to the fuel injection valve 105.

[0028] The injection pulse output from the fuel injection pulse signal calculation unit 201, the drive voltage and drive current calculated by the fuel injection drive waveform command unit 202 and applied to the fuel injection valve 105, and an amount of displacement of a valve body 203 of the fuel injection valve 105 are calculated with respect to the Fig. 3, Fig. 4 and Fig. 5 described.

[0029] Fig. 3 shows a configuration example and an operation example of a fuel injection valve incorporating a two-stage variable lift mechanism, with the graphic representation on the left side in Fig. 3 shows the value in a closed state, the graphical representation in the middle in Fig. 3 shows an example (hereinafter referred to as a deep lift) in which a tip of the valve body 303 is separated by St1 from a valve seat 306 to form a fuel passage, and the graph on the right side in Fig. 3 shows an example (hereinafter referred to as a high lift) in which the tip of the valve body 303 is separated by St1 + St2 from the valve seat 306 to form a fuel passage.

[0030] The Fig. 4 and Fig. 5 show in time series examples of the injection pulse, the drive voltage, the drive current and the displacement of the valve body 303 (the valve displacement) when fuel is injected from the fuel injection valve 105, Fig. 4 shows the example of driving with a deep stroke and Fig. 5 shows the example of driving with a high stroke.

[0031] First, the driving with the deep stroke (the driving with deep stroke) is compared with the left and middle graphs according to Fig. 3 and Fig. 4 described.

[0032] From time T0 to time T1, the fuel injection drive units 207a and 207b are in the OFF state, and no drive current is supplied to the fuel injection valve 105 because the injection pulse output from the fuel injection pulse signal calculation unit 201 is in an OFF state. Therefore, the valve body 303 is biased in the valve closing direction of the valve seat 306 by a biasing force of a setting spring 308 of the fuel injection valve 105, and a lower end of the valve body 303 remains in contact with the valve seat 306 (a valve hole 307 remains closed), and no fuel is injected, as shown in the left graph of FIG. Fig. 3 is shown.

[0033] Next, at time T1, the injection pulse is turned on, the fuel injection drive unit (Hi) 207a and the fuel injection drive unit (Lo) 207b are turned on, and when the high voltage 210, the fuel injection valve 105, and a ground voltage are electrically connected (the drive voltage applied to the solenoid 305 is the high voltage 210) and a drive current is supplied to the solenoid 305, a magnetic flux is generated between a fixed core 304 and a movable core 1301, and a magnetic attraction force acts on the movable core 1301. When the drive current supplied to the solenoid 305 increases and the magnetic attraction force acting on the movable core 1301 exceeds the biasing force of a return spring 309, the movable cores 1 and 2 301 and 302 start to move while being attracted in the direction of the fixed core 304 (time T1 to time T2).

[0034] When the movable core 1 301 and the movable core 2 302 have been moved by a predetermined length, the movable core 2 302 and the valve body 303 are engaged with each other, the movable cores 1 and 2 301 and 302 and the valve body 303 start to move together as one body (with the movable core 2 302 pushing the valve body 303 upward) (time T2), and the valve body 303 is moved away from the valve seat 306, so that the valve is opened and fuel is injected.

[0035] The movable cores 1 and 2 301 and 302 and the valve body 303 are moved together as one body until the movable core 1301 collides with the fixed core 304. When the movable core 1301 and the fixed core 304 collide violently with each other, the movable core 1301 rebounds from the fixed core 304, disrupting the flow rate of fuel injected from the valve hole 307. Therefore, before the movable core 1301 collides with the fixed core 304 (time T3), that is, when the drive current reaches a peak current Ip1, the fuel injection drive units 207a and 207b are turned off, and the drive voltage applied to the solenoid 305 is reduced to reduce the drive current, so that the momentum of the movable core 1301 and the valve body 303 is reduced.

[0036] From time T4 to time T6, when the injection pulse falls, while the fuel injection driving unit (Lo) 207b is maintained in an ON state to supply only a magnetic attraction force sufficient to attract the movable core 1301 to the fixed core 304, the fuel injection driving unit (Hi) 207a is intermittently turned on (the fuel injection driving unit (Hi) 207a is subjected to PWM control), and the drive voltage applied to the solenoid 305 is intermittently set to the battery voltage 209, so that the drive current flowing through the solenoid 305 is controlled to be within a predetermined range.

[0037] At time T5 before time T6, the movable core 1301 and the fixed core 304 collide with each other, whereby the valve body 303 is displaced by a stroke amount St1.

[0038] At time T6, when the injection pulse is turned off, both fuel injection drive units 207a and 207b are turned off, the drive voltage applied to the solenoid 305 is reduced, and the drive current flowing through the solenoid 305 is reduced, so that the magnetic flux generated between the fixed core 305 and the movable core 301 gradually disappears, and the magnetic attraction force acting on the movable core 301 disappears. Therefore, the valve body 303 is pushed back in the valve-closing direction of the valve seat 306 with a predetermined time delay due to the biasing force of the actuating spring 308 and the urging force of the fuel pressure. Then, at time T7, the valve body 303 is returned to the original position, the lower end of the valve body 303 comes into contact with the valve seat 306, and consequently, the valve is closed and no fuel is injected.

[0039] Moreover, from time T6 when the injection pulse is turned off, the high voltage 210 is supplied in a direction opposite to the direction when the fuel injection valve 105 is driven, so that the residual magnetic force in the fuel injection valve 105 is quickly removed and the valve body 303 is closed early.

[0040] Next, the high-stroke driving (high-stroke driving) is compared with the left and right graphs according to Fig. 3 and Fig. 5. The description, which overlaps that of the case of the deep stroke described above, will not be repeated.

[0041] When the injection pulse is turned on at time T1, the high voltage 210, the fuel injection valve 105, and the ground voltage are electrically connected (the drive voltage applied to the solenoid 305 is the high voltage 210), a magnetic attraction force acts on the movable core 1301 and the movable core 2 302, and the movable core 1301 and the movable core 2 302 start to move while being attracted in the direction of the fixed core 304 (time T1 to time T2).

[0042] When the movable core 1 301 and the movable core 2 302 are moved by a predetermined length, the movable core 2 302 and the valve body 303 engage with each other, the movable core 1 301, the movable core 2 302, and the valve body 303 start to move together as one body (time T2), and then the movable core 1 301, which is a short distance from the fixed core 304, abuts against the fixed core 304. Thereafter, the movable core 2 302 and the valve body 303 are moved together (with the movable core 2 302 pushing the valve body 303 upward) until the movable core 2 302 abuts against the fixed core 304, and when the valve body 303 is displaced from the valve seat 306 by the lift amount St1 + St2, the movable core 2 302 abuts against the fixed core 304.

[0043] Before the movable core 2 302 collides with the fixed core 304 (time T3), that is, when the drive current reaches a peak current Ip2 (Ip2 > Ip1), the drive voltage applied to the solenoid 305 is reduced to reduce the drive current, so that the momentum of the movable core 2 302 and the valve body 303 is reduced.

[0044] From time T4 to time T6 when the injection pulse falls as in the case of the deep lift, the drive voltage is intermittently set to the battery voltage 209 to maintain the open state of the valve, and the drive current flowing through the solenoid 305 is controlled to be within a predetermined range.

[0045] At time T6, when the injection pulse is turned off, the magnetic attraction force acting on the movable core 1301 and the movable core 2 302 disappears and the valve body 303 is pushed down to the valve seat 306, so that the valve is closed.

[0046] Fig. 6 is a graph showing an injection amount characteristic (Ti-Q characteristic) when the fuel injection valve 105 is driven at a high lift and a low lift.

[0047] As described above, with regard to the deep stroke, a Fig. 6 is obtained because the displacement amount of the valve body 303 is St1, whereby it is possible to ensure the linearity of the injection quantity with respect to the injection pulse width even for the small amount injection range. Meanwhile, with respect to the high lift, the displacement amount of the valve body 303 is shifted by St1 + St2. Accordingly, the Fig. 6, the Ti-Q characteristic curve 2 602 is obtained for the high lift, whereby a relatively large amount of fuel can be injected with the same injection pulse width compared to the low lift.

[0048] By measuring the Ti-Q characteristics through experiments and storing them in advance in a map, the injection pulse width for the required injection quantity can be calculated. In addition, the Ti-Q characteristics also vary according to fuel pressure. As the fuel pressure increases, the injection quantity increases with respect to the valve opening time, while as the fuel pressure decreases, the injection quantity decreases. Therefore, it is necessary to calculate the Ti-Q characteristics according to the fuel pressure sensor 126 (see Fig. 1) to correct the measured fuel pressure value. It is preferable that the correction value be measured in advance through experiments or the like, and the injection pulse is calculated by multiplying the injection pulse width determined using the required injection amount by the correction value.

[0049] As described above, when the required injection quantity is small and high accuracy is required, the fuel injection valve 105 is driven by the Fig. 4 flows through the solenoid 305. Meanwhile, if it is necessary to inject a large volume of fuel in a short period of time, the lift amount of the fuel injection valve 105 can be appropriately controlled by the Fig. 5 shows the peak current Ip2 (Ip1 < Ip2) flowing through the solenoid 305.

[0050] However, as in Fig. 7, a command drive current value 701 calculated by the fuel injection drive waveform command unit 202 is subjected to the influence by the variation of the working difference of the fuel injection control device 127 and the like, so that when it actually flows through the solenoid 305, an error occurs with respect to the drive current value calculated by the fuel injection drive waveform command unit 202.In addition, due to the variation in the machining difference of the fuel injection valve 105, there is a region 703 in which the drive current value is not clearly determined between the high-lift driving and the low-lift driving, and when the actual drive current 702 actually flowing through the solenoid 305 reaches the value in the region 703, the actual drive stroke (the actual drive stroke) may be driven with a stroke amount different from the command drive stroke (the drive stroke instructed by the engine state sensing unit 203 according to the operating state of the internal combustion engine 101).When the fuel injection valve 105 is driven with a lift amount different from the command drive stroke, there is a possibility that the required fuel injection amount is too small or too large, thus causing deterioration of exhaust emission and rotation variation of the internal combustion engine 101. For this reason, it is necessary to appropriately control the fuel injection valve 105 when the actual drive stroke is sensed and monitored and the actual drive stroke is different from the command drive stroke.

[0051] Sensing whether the above-described fuel injection valve 105 is driven with the high lift or the low lift can be performed by detecting an inflection point appearing in the drive current during the valve opening operation of the fuel injection valve 105 or by detecting an inflection point appearing in the drive voltage during its valve closing operation.

[0052] As in Fig. 2, therefore, the inflection point detection unit 211 of the fuel injection control device 127 detects the inflection point from the drive current during the valve-opening operation of the fuel injection valve 105 or from the drive voltage during its valve-closing operation, and the drive sampling unit 212 samples the drive stroke (lift amount) of the fuel injection valve 105 based on the detection result of the inflection point detection unit 211, and outputs the sampled result to the engine state sampling unit 203.

[0053] First, the inflection point occurring in the drive current due to the opening operation of the fuel injection valve 105 and the inflection point occurring in the drive voltage due to the valve closing operation are outlined.

[0054] When the valve body 303 of the fuel injection valve 105 is opened, a high voltage 210 is applied to the solenoid 305, and a relatively large driving current flows to accelerate the movable cores 1 and 2 301 and 302 and the valve body 303, as described above. Next, after the high voltage 210 applied to the solenoid 305 is turned off and the driving current flowing through the solenoid 305 is reduced to a predetermined value, the movable cores 1 and 2 301 and 302 abut against the fixed core 304 in a state where the driving current stably flows through the solenoid 305 when the battery voltage 209 is applied to the solenoid 305. When the movable cores 1 and 2 301 and 302 collide with the fixed core 304, the acceleration of the movable cores 1 and 2 301 and 302 is changed, changing the inductance of the solenoid 305.

[0055] While it is considered here that the change in the inductance of the solenoid 305 occurs as an inflection point in the drive current flowing through the solenoid 305 or the drive voltage applied to the solenoid 305, the inflection point does not occur in the drive voltage but occurs in the drive current because the voltage is maintained almost constant at the time of opening the valve.

[0056] Meanwhile, at the time of closing the valve body 303 of the fuel injection valve 105, when the valve body 303 abuts the valve seat 306, the return spring 309 changes from extension to compression, and when the moving direction of the movable cores 1 and 2 301 and 302 is reversed, the acceleration is changed, and the inductance of the solenoid 305 is changed. At the time of valve closing, when the drive current flowing through the solenoid 305 is turned off, a counter electromotive force is applied to the solenoid 305, and the drive current converges, the counter electromotive force is gradually reduced. Therefore, the inductance is changed as the counter electromotive force decreases to create an inflection point in the drive voltage.

[0057] That is, in the present specification, the inflection point serving as a sampling reference of the valve lift (the actual valve lift) of the fuel injection valve 105 appearing in the drive current flowing through the solenoid 305 or in the drive voltage applied to the solenoid 305 is a point at which a temporal change in the inductance of the solenoid 305 is equal to or greater than a predetermined threshold value.

[0058] Next, the Fig. 8 and Fig. 9 the difference in the generation of the inflection point of the fuel injection valve 105 due to the Fig. 3 shown valve lift.

[0059] Fig. 8 is a graph showing an example in which a drive current flows through the solenoid 305 with the peak current Ip1 to drive at the deep stroke.

[0060] When the fuel injection valve 105 is opened, the high voltage 210 is applied to the solenoid 305, with the current flowing until the drive current reaches the peak current Ip1, as based on Fig. 4. When the drive current reaches the peak current Ip1, the high voltage 210 applied to the solenoid 305 is turned off, and the battery voltage 209 is applied to it. The movable core 1301 collides with the fixed core 304 in a state where the drive current stably flows through the solenoid 305, thus reversing the direction of movement of the movable core 1301. Therefore, the acceleration of the movable core 1301 is suddenly changed, the inductance of the solenoid 305 is changed, and an inflection point 401 is generated in the drive current.

[0061] Meanwhile, when the fuel injection valve 105 is closed after the injection pulse is turned off, the magnetic attraction force is reduced, and the movable core 1301 is moved away from the fixed core 304, whereby the movable core 1301 and the valve body 303 are moved toward the valve seat 306. When the valve body 303 is in contact with the valve seat 306, the return spring 309 is gradually compressed, but changes to extension upon contact. Consequently, the moving direction of the movable core 1301 is reversed, and the acceleration of the movable core 1301 is suddenly changed. Due to the change in the acceleration of the movable core 1301, the inductance of the solenoid 305 is changed, and the counter electromotive force is changed. Therefore, an inflection point 402 is generated in the drive voltage.

[0062] Fig. 9 is a graph showing an example in which a drive current flows through the solenoid 305 with the peak current Ip2 to drive at the high stroke.

[0063] When the fuel injection valve 105 is opened, the high voltage 210 is applied to the solenoid 305 so that the current flows until the drive current reaches the peak current Ip2, as based on Fig. 5. Then, a magnetic attraction force is generated between the movable core 1301 and the fixed core 304, accelerating the movable core 1301 and the movable core 2 302. When the drive current reaches the peak current Ip2, the high voltage 210 applied to the solenoid 305 is turned off, the flowing drive current is reduced to a predetermined value, and then the battery voltage 209 is applied to the solenoid 305. In a state where the drive current stably flows through the solenoid 305, the movable core 1301, which is a relatively short distance from the fixed core 304, abuts against the fixed core 304, and then the movable core 2 302, which is a relatively long distance from the fixed core 304, abuts against the fixed core 304.In this way, when the movable core 1301 and the movable core 2 302 each sequentially collide with the fixed core 304, the acceleration is suddenly changed, consequently changing the inductance of the solenoid 305 and generating two relatively large inflection points 501 and 502 in the drive current.

[0064] Meanwhile, when the fuel injection valve 105 is closed after the injection pulse is turned off, the magnetic attraction force is reduced, and the movable core 1301 and the movable core 2 302 are moved away from the fixed cores 304. Because the movable core 2 302, which has a smaller residual magnetic force, moves faster in the direction toward the valve seat 306 compared to the movable core 1301, the movable core 2 (302) first collides with the movable core 1 (301), and the acceleration of the movable core 1 (301) is suddenly changed. After that, the movable core 1301 and the movable core 2 302 start to move simultaneously (integrally), and the valve body 303 is finally brought into contact with the valve seat 306 and closed.At this time, the return spring 309 is gradually compressed, but changes to extend upon impact, causing a sudden change in the acceleration of the movable core 1301 and the movable core 2 302. Because this changes the inductance of the solenoid 305 and appears as a change in the counter electromotive force, a relatively large inflection point 504 is generated in the drive voltage. That is, two inflection points are generated in the drive voltage here: the inflection point 503 generated by the collision between the movable core 2 302 and the movable core 1301, and the inflection point 504 generated by impact.

[0065] In the fuel injection valve 105 including a variable lift mechanism that relatively moves a plurality of movable cores 1 and 2 301, 302 associated with the fixed core 304 or the valve body 303 and that moves the valve body 303 stepwise to adjust the lift amount, at the time of low lift driving, the number of inflection points occurring in the drive current due to the valve opening operation and the number of inflection points occurring in the drive voltage due to the valve closing operation are both one, as described above, while at the time of high lift driving, the number of inflection points occurring in the drive current due to the valve opening operation and the number of inflection points occurring in the drive voltage due to the valve closing operation are both two.

[0066] Therefore, the drive sampling unit 212 of the fuel injection control device 127 can sample and monitor the actual drive stroke (the actual drive stroke) of the fuel injection valve 105 from the number of inflection points detected by the inflection point detection unit 211, a manner in which the inflection points appear, and the like.

[0067] Next, the sampling of the actual drive stroke of the fuel injection valve 105 and the injection quantity control based on the sampling by the Fig. 1 shown fuel injection control device 127 related drive stroke limitation using the flow chart according to Fig. 10 described.

[0068] As in Fig. 10, first, in step S901, the inflection point is detected from the time-series data of the drive current during the valve-opening operation or the drive voltage during the valve-closing operation of the fuel injection valve 105. Next, in step S902, sampling of the actual drive stroke of the fuel injection valve 105 is performed. The actual drive stroke can be sampled by specifying the high-lift and low-lift operating characteristics from the inflection point detected in step S901. Next, determination of the actual drive stroke is performed in step S903. It is determined whether the actual drive stroke specified in step S902 corresponds to the stroke commanded by the fuel injection drive waveform command unit 202 (the command drive stroke). If the command drive stroke and the actual drive stroke correspond to each other in step S903, this routine ends.Meanwhile, if the command drive stroke and the actual drive stroke do not correspond to each other, the process goes to step S904, where the limitation of the drive stroke (the command drive stroke) is executed. [Turning point detection]

[0069] The inflection point detection by the inflection point detection unit 211 described above in step S901 will be described.

[0070] When performing second-order differentiation of the time series data of the drive current flowing through the solenoid 305 or the drive voltage applied to the solenoid 305, the inflection point described above appears as an extreme value (maximum value or minimum value). Therefore, the inflection point described above can be specified by detecting the extreme values of the time series data.

[0071] Fig. 11 shows the time series data of a drive voltage during a valve closing operation at the time of high lift driving and its second-order differential value, Fig. 12 shows the time series data of a drive voltage during a valve closing operation at the time of deep lift driving and its second-order differential value, Fig. Fig. 13 shows the time series data of a drive current during a valve opening operation at the time of high lift driving and its second-order differential value, and Fig. 14 shows the time series data of a drive current during a valve opening operation at the time of deep lift driving and its second-order differential value.

[0072] When the S / N ratio of the measured drive current or drive voltage is low and the noise level is high, it is difficult to sample the extreme value from the result of the second-order derivative of the time series data of the drive current or drive voltage. Therefore, a desired extreme value can be detected by applying a low-pass filter or the like to the drive current or drive voltage and performing a second-order derivative on the smoothed time series data. The second-order differential value of the drive voltage and the second-order differential value of the drive current, which are shown in the Fig. 11 to 14 are obtained by filtering the drive voltage and drive current and performing a second-order derivative on the smoothed data.

[0073] In addition, when the second-order derivative is performed on the time series data of the drive current from the time the injection pulse is turned on or on the time series data of the drive voltage from the time the injection pulse is turned off, the inflection point generated by the acceleration change of the movable cores 1 and 2 301 and 302 cannot be accurately specified because an extreme value may appear at the time of switching the voltage (e.g., switching from the high voltage 210 to the battery voltage 209 or exerting the counter electromotive force after turning off the drive voltage) or the like.Therefore, the time series data subjected to the second-order derivative are preferably the time series data of the drive current after a certain period of time has passed since the injection pulse was turned on (in other words, since the drive voltage or the drive current was turned on), or the time series data of the drive voltage after a certain period of time has passed since the injection pulse was turned off (in other words, since the drive voltage or the drive current was turned off). [Scanning the actual drive stroke]

[0074] Next, the sampling of the actual drive stroke by the drive sampling unit 212 in step S902 is performed with respect to the Fig. 15 to 18 are described in detail. In step S902, an actual drive stroke is sampled using the extreme value detected in step S901. {Method for sensing the actual drive stroke (Part 1)}

[0075] Fig. Figure 15 shows an example in which the second-order derivative is performed on the drive voltage during the valve closing operation. As already described, there is a difference in the number of inflection points (the number of inflection points) between low-lift driving and high-lift driving. When driving at the high lift, the number of detected inflection points is two, while when driving at the low lift, the number of inflection points is one. Because the inflection points appear as the extreme values, the number of inflection points can be specified by counting the number of extreme values from the second-order differential value. In other words, the actual drive stroke when the number of extreme values is two (1501 and 1502) can be considered a high lift (the left side in Fig. 15), while the actual drive stroke, when the number of extreme values is one (1505), can be determined as a deep stroke (the right side in Fig. 15). In the Fig. In the example shown in Figure 15, each time the extreme value is counted (that is, each time the inflection point is detected), it is determined that the actual drive stroke is sequentially increased. When counting the extreme values, the absolute value of the second-order differential value may be used. In addition, to prevent false detection of the extreme values, the value may be determined as an extreme value only when the predetermined threshold values 1503 and 1504 are set and the second-order differential value is equal to or greater than, or equal to or less than, the predetermined threshold value. The predetermined threshold value can be determined in advance through experiments and can be variably set based on the fuel pressure and the counter electromotive force applied to the solenoid 305.

[0076] Fig. 15 shows the example of the drive voltage during the valve closing operation, but the same applies to the drive current during the valve opening operation. {Method for sensing the actual valve lift (Part 2)}

[0077] Furthermore, a method for sensing an actual valve lift, which is different from the method described above, is disclosed with respect to Fig. 16 described.

[0078] Because the lift amount differs between low-lift driving and high-lift driving, the period until valve opening is completed after the injection pulse is turned on and the period until valve closing is completed after the injection pulse is turned off are relatively different between low-lift driving and high-lift driving. At the time of low-lift driving with a relatively short lift amount, the period from turning on the injection pulse to the generation of the inflection point that occurs when valve opening is completed, or the period from turning off the injection pulse to the generation of the inflection point that occurs when valve closing is completed, is shorter compared to the period of high-lift driving.Accordingly, when the period from turning on the injection pulse to the extreme value is shorter than the predetermined value or when the period from turning off the injection pulse to the extreme value is shorter than a predetermined value 1602, the actual valve lift can be determined as a deep lift (the right side in . Fig. 16), while if the period from turning on the injection pulse to the extreme value is longer than the specified value or if the period from turning off the injection pulse to the extreme value is longer than the specified value 1602, the actual valve lift can be determined as a high lift (the left side in Fig. 16). The predetermined value 1602 can be determined in advance through experiments and can be variably set based on the fuel pressure value and the counter electromotive force applied to the solenoid 305. To prevent false detection of the inflection points due to the application of the counter electromotive force after the injection pulse is turned off, and the like, a mask period 1601 is provided, and second-order differentiation is performed on the time series data after the mask period 1601 has passed.

[0079] The extreme value can be detected using the absolute value of the second-order differential value. In addition, to prevent false detection of the extreme values, the value can only be determined as an extreme value when the predetermined threshold values 1603 and 1604 are set and the second-order differential value is equal to or greater than, or equal to or less than, the predetermined threshold value. The predetermined threshold value can be determined in advance through experimentation and can be variably set based on the fuel pressure value and the counter electromotive force applied to the solenoid 305.

[0080] Fig. 16 shows an example of the drive voltage during the valve closing operation, but the same applies to the drive current during the valve opening operation. {Method for sensing the actual valve lift (Part 3)}

[0081] Furthermore, a method for sensing an actual valve lift, which is different from the method described above, is disclosed with respect to Fig. 17 described.

[0082] Furthermore, because the lift amount is relatively different between the low-lift driving and the high-lift driving, the acceleration of the movable cores 1 and 2 301 and 302 of the fuel injection valve 105 differs depending on the drive stroke. When the lift amount (at the time of high-lift driving) is relatively large, the acceleration of the movable core is also relatively large, and the absolute value of the extreme value obtained by the second-order derivative is also relatively larger than the extreme value at the time of low-lift driving. Therefore, the actual drive stroke can be estimated based on the magnitude of the absolute value of the extreme value. In other words, when the absolute values of the extreme values 1701 and 1702 are larger than the predetermined threshold value 11704, the actual drive stroke can be determined as the high lift (the left side in Fig. 17), while if the absolute value of the extreme value 1705 is smaller than the predetermined threshold value 1 1704, the actual drive stroke can be determined as the deep stroke (the right side in Fig. 14).

[0083] In addition, to prevent false detection of the extreme values, the value can be determined as an extreme value only when a predetermined threshold value 2 1703 is set and (the absolute value of the second-order differential value) the second-order differential value is equal to or greater than the predetermined threshold value 2 1703. The predetermined threshold value 2 or the predetermined threshold value 1 can be determined in advance through experiments and can be variably set based on the fuel pressure value or the counter electromotive force applied to the solenoid 305.

[0084] Fig. 17 shows an example of the drive voltage during the valve closing operation, but the same applies to the drive current during the valve opening operation.

[0085] In the Fig. In the example shown in Figure 17, based on the magnitude of the extreme value, and more specifically, since the absolute value of the extreme value is larger, it is determined that the actual driving stroke is larger. However, because the acceleration change of the movable core increases as the stroke amount increases, as described above, a virtual driving voltage (a driving voltage when it is assumed that there is no or a small sudden acceleration change due to the collision of the movable core) or a virtual driving current (a driving current when it is assumed that there is no or a small sudden acceleration change due to the collision of the movable core) at the time of generation of the inflection point is assumed,a change contract (a difference) of the actual drive voltage or the actual drive current with respect to the virtual drive voltage or the virtual drive current at the time of generating the inflection point is calculated, wherein, when the change amount is relatively large, the actual valve lift can be determined as the high lift, while when the change amount is relatively small, the actual valve lift can be determined as the low lift. {Method for sensing the actual valve lift (Part 4)}

[0086] Furthermore, a method for sensing the actual valve lift, which is different from the method described above, is proposed with respect to Fig. 18 described.

[0087] In the low-stroke driving and the high-stroke driving, the directions of change of the acceleration of the movable cores 1 and 2 301 and 302 when the inflection point is generated are different from each other, and consequently the directions (orientation) of the extreme value are also different from each other.

[0088] In the case of high-lift driving, at the inflection point generated during the valve closing operation, the movable core 1301 2 moves toward the valve seat 306, colliding with the movable core 1301 because the magnetic attraction force is reduced after the injection pulse is turned off. In this case, the acceleration of the movable core 1301 is increased by applying a force in the moving direction of the movable core 1301 due to the collision of the movable core 1302 2. Meanwhile, when the valve is closed, the moving directions of the movable core 1301 2 and the movable core 1302 2 are reversed by the return spring 309.

[0089] Meanwhile, in the case of the deep lift driving, at the inflection point generated during the valve closing operation, the movable core 1301 is moved in the direction of the valve seat 306 because the magnetic attraction force is reduced after the injection pulse is turned off, and when the valve is closed, the moving direction of the movable core 1301 is reversed by the return spring 309.

[0090] In other words, the two inflection points generated during the valve closing operation at the time of high-lift driving are caused due to the acceleration changes in the moving direction and the acceleration changes in a direction opposite to the moving direction, while an inflection point generated during the valve closing operation at the time of low-lift driving is caused only due to the acceleration change in the direction opposite to the moving direction.

[0091] As in Fig. 18, the inflection point caused by the acceleration change in the moving direction at the time of high-stroke driving is a minimum value 1801, while the inflection point caused by the acceleration change in the direction opposite to the moving direction is a maximum value 1802. Furthermore, because the inflection point is caused by the acceleration change in the direction opposite to the moving direction, only a maximum value 1805 is obtained at the time of low-stroke driving. By detecting this difference, the actual driving stroke can be estimated; accordingly, when the first detected extreme value is the minimum value 1801, the actual driving stroke can be determined as the high stroke, while when the first detected extreme value is the maximum value 1802, the actual driving stroke can be determined as the low stroke.

[0092] In the various sampling methods by the drive sampling unit 212 described above, there is an advantage that the influence of the structure of the fuel injection valve 105, the control contents, and the like is small when the actual drive stroke is sampled with the number of inflection points (here, the extreme values), thus easily ensuring the sampling accuracy. [Determination of the actual drive stroke]

[0093] Next, the determination of the actual drive stroke is carried out in step S903 in Fig. 10 described.

[0094] As already described, in step S903, it is determined whether the actual drive stroke sampled in step S902 agrees with the command drive stroke commanded by the fuel injection drive waveform command unit 202. If the actual drive stroke and the command drive stroke agree with each other, this routine ends.

[0095] Meanwhile, if the actual drive stroke and the command drive stroke do not agree with each other, the process proceeds to step S904 to execute the injection amount control. Furthermore, the determination of the agreement between the actual drive stroke and the command drive stroke may be performed once, and if the actual drive stroke and the command drive stroke do not agree with each other multiple times, the process proceeds to step S904. [Drive stroke limitation]

[0096] Next, the drive stroke limitation is set by the fuel injection drive waveform command unit 202 in step S904 in Fig. 10 is described in detail. In step S904, when the above-described command drive stroke does not agree with the actual drive stroke, the command drive stroke commanded by the fuel injection drive waveform command unit 202 is limited.

[0097] More specifically, when the command drive stroke is the low lift and the actual drive stroke is the high lift, the drive current is increased so that the high lift is constantly applied from the next fuel injection. Specifically, the drive voltage is applied so that the peak current Ip1 of the command drive current is Ip2. At this time, split injection is also limited, so that the fuel can be injected with the minimum injection amount in the high lift. By limiting split injection (e.g., by prohibiting split injection or limiting the number of splits) and constantly performing high lift driving, for example, the required fuel injection amount can always be met, and fuel injection according to the target injection amount can be realized.

[0098] When the command drive stroke is high lift and the actual drive stroke is low lift, the drive current is increased so that high lift is continuously applied from the next fuel injection. Specifically, the drive current is increased so that the peak current is at the maximum value (> Ip2) to ensure high lift driving. For example, by continuously performing high lift driving, the required fuel injection amount can always be met, and fuel injection can be realized according to the target injection amount.

[0099] Further, when the command drive stroke is the high stroke and the actual drive stroke is the deep stroke, the maximum value of the drive current from the next fuel injection may be set to the peak current Ip1, and the driving may be limited to the driving with only the deep stroke.

[0100] Although the inflection points are generated due to changes in the acceleration of the movable core in the drive current during the valve-opening operation and the drive voltage during the valve-closing operation of the fuel injection valve 105, a plurality of inflection points are generated according to the operation of the movable core because the fuel injection valve 105, which includes a variable lift mechanism that can vary the lift amount, includes a plurality of movable cores as described above. Because these inflection points are determined according to the lift amount, it is possible to sample the actual drive stroke (the actually driven stroke) by detecting the inflection points. If the sampled actual drive stroke is different from the command drive stroke (the commanded drive stroke), the lift amount (the command drive stroke) can be limited, and fuel injection can be performed.

[0101] According to the fuel injection control device 127 according to the present embodiment, in the fuel injection valve 105 including a variable lift mechanism that varies the lift amount by one drive stroke in multiple stages, it is possible to avoid significant deterioration in exhaust emission and unintended torque fluctuations because the lift amount (the actual drive stroke) of the fuel injection valve 105 can be accurately sensed even when driving at a lift amount different from the intended lift amount (the command drive stroke) due to a malfunction of the fuel injection valve 105 or the like, as described above.

[0102] The present invention is not limited to the above-described embodiments, but additionally includes various modified examples. Although the above-described embodiment has been described in detail for easy understanding of the present invention, the present invention can also be applied, for example, to fuel injection valves that can vary the lift amount in three stages or more and fuel injection valves having other configurations such as a movable core. However, since the method for generating the inflection point varies depending on the configuration of the movable core, the present invention is not necessarily limited to the one having all of the above-described configurations.Furthermore, a part of the configuration of one embodiment may be replaced by the configuration of another embodiment, and the configuration of another embodiment may be added to the configuration of one embodiment. In addition, the addition, deletion, and replacement of other configurations are possible for a part of the configuration of each embodiment.

[0103] Each of the configurations, functions, processing units, processing means, and the like described above can be realized in hardware by designing part or all of them, for example, with an integrated circuit. Each of the configurations, functions, and the like described above can be realized in software by interpreting and executing a program that realizes each function with the processor. The information, such as a program, a table, a file, and the like, that realizes each function can be stored in a storage device such as a memory, a hard disk, and a solid state drive (SSD), or in a recording medium such as an IC card, an SD card, and a DVD.

[0104] Furthermore, the control lines and information lines show those that are considered necessary for explanation; not all of the control lines and information lines in the product are necessarily shown. In practice, it can be assumed that all components are interconnected. List of reference symbols 101 Internal combustion engine 105 Fuel injection valve 109 ECU 127 Fuel injection control device (control device for a fuel injection valve) 201 Fuel injection pulse signal calculation unit 202 Fuel injection drive waveform command unit (current waveform correction unit) 203 Engine condition sensing unit 206 High-voltage generation unit (increasing device) 207a Fuel injection drive unit (Hi) (switch) 207b Fuel injection drive unit (Li) (switch) 208 drive IC 211 Turning point detection unit 212 Drive scanning unit 301 movable core 1 302 movable core 2 303 valve body 304 solid core 305 Solenoid 306 valve seat 307 valve hole

Claims

[1] A control device (127) that controls a fuel injection valve (105) including a variable lift mechanism that varies a lift amount of a valve body (303) through a drive stroke of two or more stages, wherein the control device (127) for a fuel injection valve (105) detects the inflection point from a drive voltage during a valve closing operation of the fuel injection valve (105) or from a drive current during a valve opening operation and determines that the drive stroke is larger as the number of detected inflection points is larger. [2] A control device (127) that controls a fuel injection valve (105) including a variable lift mechanism that varies a lift amount of a valve body (303) through a drive stroke of two or more stages, wherein the control device (127) for a fuel injection valve (105) detects the inflection point from a drive voltage during a valve closing operation of the fuel injection valve (105) or from a drive current during a valve opening operation, and samples the drive stroke based on an orientation of an extreme value of the drive voltage or the drive current at the time of generation of the inflection point. [3] A control device (127) for a fuel injection valve (105) according to claim 1 or 2, wherein the control device (127) for a fuel injection valve (105) detects the inflection point from a drive voltage during a valve closing operation of the fuel injection valve (105) or from a drive current during a valve opening operation, and samples the drive stroke based on a period from turning off the drive voltage or the drive current of the fuel injection valve (105) to the detected inflection point or on a period from turning on the drive voltage or the drive current of the fuel injection valve (105) to the detected inflection point. [4] A control device (127) for a fuel injection valve (105) according to claim 3, wherein the control device (127) for a fuel injection valve (105) determines that the drive stroke is larger as the period is longer. [5] A control device (127) for a fuel injection valve (105) according to claim 1 or 2, wherein the control device (127) for a fuel injection valve (105) detects the inflection point from a drive voltage during a valve closing operation of the fuel injection valve (105) or from a drive current during a valve opening operation, and samples the drive stroke based on a magnitude of an extreme value of the drive voltage or the drive current at the time of generation of the inflection point. [6] A control device (127) for a fuel injection valve (105) according to claim 5, wherein the control device (127) for a fuel injection valve (105) determines that the drive stroke is larger as the absolute value of the extreme value is larger. [7] A control device (127) for a fuel injection valve (105) according to claim 1 or 2, wherein the control device (127) for a fuel injection valve (105) detects the inflection points from the drive voltage after a predetermined period of time has passed since the drive voltage or the drive current of the fuel injection valve (105) was turned off, or from the drive current after a predetermined period of time has passed since the drive voltage or the drive current of the fuel injection valve (105) was turned on. [8] A control device (127) that controls a fuel injection valve (105) including a variable lift mechanism that varies a lift amount of a valve body (303) through a drive stroke of two or more stages, wherein the control device for a fuel injection valve samples the drive stroke of the fuel injection valve based on an inflection point detected by a drive current when the fuel injection valve is opened and / or a drive voltage when the fuel injection valve is closed, wherein, if the sensed drive stroke is different from a command drive stroke commanded to the fuel injection valve (105), the control device (127) for a fuel injection valve (105) limits the command drive stroke, and wherein, when the fuel injection valve (105) is driven with a relatively high lift amount regardless of the fact that the drive stroke is commanded to be carried out with a relatively low lift amount, the control device (127) for a fuel injection valve (105) limits the command drive stroke so that the lift amount of the fuel injection valve (105) is always a relatively high lift amount. [9] A control device (127) that controls a fuel injection valve (105) including a variable lift mechanism that varies a lift amount of a valve body (303) through a drive stroke of two or more stages, wherein the control device for a fuel injection valve samples the drive stroke of the fuel injection valve based on an inflection point detected by a drive current when the fuel injection valve is opened and / or a drive voltage when the fuel injection valve is closed, wherein, if the sensed drive stroke is different from a command drive stroke commanded to the fuel injection valve (105), the control device (127) for a fuel injection valve (105) limits the command drive stroke, and wherein, when the fuel injection valve (105) is driven with a relatively low lift amount despite the fact that the drive stroke is commanded to be carried out with a relatively high lift amount, the control device (127) for a fuel injection valve (105) limits the command drive stroke so that the lift amount of the fuel injection valve (105) is always a relatively high lift amount.

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