Control device

Abstract

To surely detect a valve-closing inflection point.SOLUTION: An electromagnetic valve drive unit comprises: a maximum detection part for detecting a maximum point when time series data of a differential value of a back electromotive voltage which is generated at a solenoid are changed to reduction from an increase while going back to the data in a reverse direction reverse to a time series; and a valve-closing time detection part for detecting a maximum time being a time of the maximum point as a valve-closing time of a fuel injection valve when performing determination processing for scanning whether or not a reduction amount of the differential value from the maximum point while going back to the time series data in the reverse direction exceeds a prescribed threshold from the maximum point which is detected by the maximum detection part, and there is an event where the reduction amount exceeds the prescribed threshold.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a control device. [Background technology]

[0002] A solenoid valve drive device that drives a fuel injection valve by controlling the supply of current to the fuel injection valve is known (see Patent Document 1). This solenoid valve drive device controls the supply of current to the fuel injection valve so that the period from the closing to the opening of the fuel injection valve is constant, thereby suppressing fluctuations in the amount of fuel injected from the fuel injection valve. Specifically, the solenoid valve drive device detects the closing of the fuel injection valve and controls the supply of current to the fuel injection valve so that the time this valve is closed (hereinafter referred to as the "valve closing time") becomes a target value. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-180345 Summary of the Invention [Problem to be solved by the invention]

[0004] The inventors have found that valve closure can be detected by detecting the first inflection point (hereinafter referred to as the "valve-closing inflection point") that appears in a time series in the differentiated waveform of the back electromotive force generated in the fuel injector. Therefore, as a method for detecting the valve-closing inflection point, the inventors have devised a method for scanning the differentiated value of the back electromotive force in a time series, and when the amount of decrease from the maximum value of the differentiated value exceeds a predetermined threshold, detecting the maximum value as the valve-closing inflection point.

[0005] However, in the time-series differential value, a second inflection point may appear before the decrease from the valve-closing inflection point exceeds a predetermined threshold. Therefore, the above method may not be able to detect the first inflection point, i.e., the valve-closing inflection point.

[0006] 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 that can reliably detect a valve-closing inflection point. [Means for solving the problem]

[0007] (1) One aspect of the present invention is a control device for controlling the operation of a fuel injection valve having a solenoid coil, the control device comprising: a voltage detection unit that detects a back electromotive force generated in the solenoid coil in chronological order; a differential value calculation unit that differentiates the back electromotive force detected by the voltage detection unit with respect to time; a storage unit that stores time series data of the differential value; a maximum detection unit that traces the time series data in a direction opposite to the time series and detects a maximum point when the differential value changes from an increase to a decrease; and a valve closing time detection unit that executes a determination process that traces the time series data in the opposite direction from the maximum point detected by the maximum detection unit to scan whether an amount of decrease in the differential value from the maximum point exceeds a predetermined threshold, and if an event occurs in which the amount of decrease exceeds the predetermined threshold, detects the maximum time, which is the time of the maximum point, as a valve closing time of the fuel injection valve.

[0008] (2) In the control device of (1) above, when the maximum detection unit detects multiple maximum points, the valve closing time detection unit may execute the judgment process for each maximum point, and when there are multiple candidate valve closing points that are the maximum points when it is determined as a result of the judgment process that an event exists in which the decrease amount exceeds the predetermined threshold, the shortest maximum time among the maximum times of the candidate valve closing points may be detected as the valve closing time.

[0009] (3) In the control device of (1) above, when the maximum detection unit detects multiple maximum points, the valve closing time detection unit executes the judgment process for each maximum point, and when there are multiple candidate valve closing points that are the maximum points when it is determined as a result of the judgment process that an event exists in which the decrease amount exceeds the predetermined threshold, the maximum time of the candidate valve closing point with the largest decrease amount among the candidate valve closing points may be detected as the valve closing time.

[0010] (4) In any of the control devices described in (1) to (3), the fuel injection valve may have a valve seat, a valve body that opens and closes the fuel passage by moving away from or abutting against the valve seat, a needle with the valve body fixed to its tip, and a movable core that is arranged coaxially with the needle 5, and the valve body may be configured to be pulled up by a magnetic force generated when current is passed through the solenoid coil. [Effects of the Invention]

[0011] As described above, according to the present invention, the valve-closing inflection point can be reliably detected. [Brief explanation of the drawings]

[0012] [Figure 1] 2 is a configuration example of a fuel injection valve L according to the present embodiment. [Figure 2] 1 is a configuration example of an electromagnetic valve driving device 1 according to the present embodiment. [Figure 3] FIG. 2 is a diagram illustrating an example of time-series data according to the embodiment. [Figure 4] 5A and 5B are diagrams illustrating an example of a method for detecting a valve closing time according to the present embodiment. [Figure 5] FIG. 3 is a diagram illustrating an example of the flow of operations of the control device 300 according to the present embodiment. [Figure 6] 10A and 10B are diagrams illustrating the effects of the present embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0013] The electromagnetic valve drive device 1 according to this embodiment is a drive device that drives a fuel injection valve L. Specifically, the electromagnetic valve drive device 1 according to this embodiment is a solenoid valve drive device that drives a fuel injection valve L (electromagnetic valve) that injects fuel into an internal combustion engine mounted on a vehicle.

[0014] The fuel injection valve L is an electromagnetic valve (solenoid valve) that injects fuel into an internal combustion engine such as a gasoline engine or a diesel engine mounted on a vehicle. An example of the configuration of the fuel injection valve L will be described below with reference to FIG.

[0015] 1, the fuel injection valve L includes a fixed core 2, a valve seat 3, a solenoid coil 4, a needle 5, a valve element 6, a retainer 7, a lower stopper 8, a valve element biasing spring 9, a movable core 10, and a movable core biasing spring 11. In this embodiment, the fixed core 2, the valve seat 3, and the solenoid coil 4 are fixed members, and the needle 5, the valve element 6, the retainer 7, the lower stopper 8, the valve element biasing spring 9, the movable core 10, and the movable core biasing spring 11 are movable members.

[0016] The fixed core 2 is a cylindrical member and is fixed to a housing (not shown) of the fuel injection valve L. The fixed core 2 is made of a magnetic material. The valve seat 3 is fixed to the housing of the fuel injection valve L. The valve seat 3 has an injection hole 3a. The injection hole 3a is a hole through which fuel is injected, and is closed when a valve element 6 is seated on the valve seat 3 and is opened when the valve element 6 is separated from the valve seat 3.

[0017] The solenoid coil 4 is formed by winding an electric wire in a circular shape. The solenoid coil 4 is arranged concentrically with the fixed core 2. The solenoid coil 4 is electrically connected to the electromagnetic valve drive device 1. When current is applied from the electromagnetic valve drive device 1, the solenoid coil 4 forms a magnetic path including the fixed core 2 and the movable core 10.

[0018] The needle 5 is a long rod member extending along the central axis of the fixed core 2. The needle 5 moves in the axial direction of the central axis of the fixed core 2 (the direction in which the needle 5 extends) due to an attractive force generated by a magnetic path including the fixed core 2 and the movable core 10. In the following description, the direction in the axial direction of the central axis of the fixed core 2 in which the movable core 10 moves due to the attractive force is referred to as "upward," and the direction opposite to the direction in which the movable core 10 moves due to the attractive force is referred to as "downward."

[0019] The valve element 6 is formed at the lower tip of the needle 5. The valve element 6 closes the injection hole 3a when seated on the valve seat 3, and opens the injection hole 3a when separated from the valve seat 3. The retainer 7 includes a guide member 71 and a flange 72. The guide member 71 is a cylindrical member fixed to the upper tip of the needle 5. The flange 72 is formed at the upper end of the guide member 71 so as to protrude in the radial direction of the needle 5. The lower end face of the flange 72 is an abutment surface with the movable core biasing spring 11. The upper end face of the flange 72 is an abutment surface with the valve element biasing spring 9. For example, the valve element 6 is a needle valve separate from the movable core 10, and is pulled up by magnetic force generated when current is applied to a solenoid coil.

[0020] The lower stopper 8 is a cylindrical member fixed to the needle 5 between the valve seat 3 and the guide member 71. The upper end face of the lower stopper 8 is the contact surface with the movable core 10.

[0021] The valve disc biasing spring 9 is a compression coil spring housed inside the fixed core 2, and is interposed between the inner wall surface of the housing and the flange 72. The valve disc biasing spring 9 biases the valve disc 6 downward. That is, when the coil 14 is not energized, the biasing force of the valve disc biasing spring 9 causes the valve disc 6 to abut against the valve seat 3.

[0022] The movable core 10 is disposed between the guide member 71 and the lower stopper 8. The movable core 10 is a cylindrical member and is provided coaxially with the needle 5. A through-hole through which the needle 5 is inserted is formed in the center of the movable core 10, and the movable core 10 is movable in the direction in which the needle 5 extends. The upper end face of the movable core 10 is an abutment surface with the retainer 7, the fixed core 2, and the movable core biasing spring 11. On the other hand, the lower end face of the movable core 10 is an abutment surface with the lower stopper 8. The movable core 10 is formed of a magnetic material.

[0023] The movable core biasing spring 11 is a compression coil spring interposed between the flange 72 and the movable core 10. The movable core biasing spring 11 biases the movable core 10 downward. That is, when the solenoid coil 4 is not supplied with power, the movable core 10 is brought into contact with the lower stopper 8 by the biasing force of the movable core biasing spring 11.

[0024] Next, the electromagnetic valve driving device 1 according to this embodiment will be described.

[0025] As shown in FIG. 2, the electromagnetic valve driving device 1 includes a driving device 200 and a control device 300.

[0026] The driving device 200 includes a power supply device 210 and a switch 220 .

[0027] The power supply device 210 includes at least one of a battery and a boost circuit. The battery is mounted on a vehicle. The boost circuit boosts a battery voltage Vb, which is the output voltage of the battery, and outputs the boosted voltage Vs.

[0028] The power supply device 210 energizes the solenoid coil 4 by outputting a boosted voltage Vs to the solenoid coil 4. The power supply device 210 may energize the solenoid coil 4 by outputting a battery voltage Vb to the solenoid coil 4. The voltage output from the power supply device 210 to the solenoid coil 4 is controlled by the control device 300. The energization of the solenoid coil 4 is also controlled by the control device 300.

[0029] The switch 220 is controlled to an on state or an off state by the control device 300. When the switch 220 is controlled to an on state, the voltage output from the power supply device 210 is supplied to the solenoid coil 4. This starts the flow of electricity to the solenoid coil 4. When the switch 220 is controlled to an off state, the supply of voltage from the power supply device 210 to the solenoid coil 4 is stopped.

[0030] The control device 300 includes a voltage detection unit 310 and a control unit 320 .

[0031] The voltage detection unit 310 detects the voltage value Vc generated in the solenoid coil 4 in chronological order. For example, the voltage Vc is the voltage across both ends of the solenoid coil 4. The voltage detection unit 310 outputs the detected voltage value Vc to the control unit 320. The voltage detection unit 310 detects the back electromotive force generated in the solenoid coil 4 in chronological order. Here, the back electromotive force is the voltage value Vc after the power supply to the solenoid coil 4 is stopped.

[0032] The control unit 320 controls the amount of fuel injected from the fuel injection valve L (hereinafter referred to as the "fuel injection amount") to be constant by controlling the time that current is applied to the solenoid coil 4. The control unit 320 detects valve closure by detecting the first inflection point (hereinafter referred to as the "valve closing inflection point") that appears in the differential waveform of the back electromotive force of the solenoid coil 4 detected by the voltage detection unit 310. For example, the control unit 320 detects the time at which the valve closing inflection point appears as the valve closing time. The control unit 320 then corrects the time that current is applied to the solenoid coil 4 so that the valve closing time becomes a target value, thereby controlling the fuel injection amount to be constant. As an example, the valve closing time is the time from when current is applied to the solenoid coil 4 starts to when the fuel injection valve L closes, but is not limited to this and may be the time from when current is stopped from the solenoid coil 4 to when the fuel injection valve L closes.

[0033] The following describes the functional units of the control unit 320. The control unit 320 includes an energization control unit 330, a filter unit 340, a differential calculation unit 350, a storage unit 360, a maximum detection unit 370, a valve closing time detection unit 380, and a correction unit 390.

[0034] The current control unit 330 controls the power supply device 210. The current control unit 330 controls the switch 220 to an on state or an off state. By controlling the switch 220 to an on state, the current control unit 330 supplies voltage from the power supply device 210 to the solenoid coil 4. By controlling the switch 220 from an on state to an off state, the current control unit 330 stops the supply of voltage from the power supply device 210 to the solenoid coil 4. The current control unit 330 controls the current supply time Ti (= T2 - T1), which is the time (current supply stop time) T2 from when current starts to be supplied to the solenoid coil 4 at a preset current supply start time T1 to when the current supply is stopped, thereby controlling the injection amount of fuel injected from the fuel injection valve L (hereinafter referred to as the "fuel injection amount") to be constant.

[0035] When the supply of voltage to the solenoid coil 4 is stopped, a counter electromotive force is generated in the solenoid L, and a counter electromotive voltage is generated across both ends of the solenoid L. This counter electromotive voltage decreases over time and disappears after a predetermined time has passed. Before this voltage difference disappears, the valve element 6 of the fuel injection valve L, which had been open, collides with the valve seat 3 and closes, and when the valve element 6 collides with the valve seat 3, the rate at which the voltage difference decreases changes. The control unit 320 of this embodiment detects the change in this rate of decrease, thereby detecting the closure of the fuel injection valve L.

[0036] The filter unit 340 performs a filtering process on the voltage value Vc output from the voltage detection unit 310. This voltage value Vc is the voltage value Vc after the switch 220 is controlled to change from an on state to an off state, and is a so-called back electromotive force voltage. The filtering process is a process of removing noise components contained in the voltage waveform of the voltage value Vc using a low-pass filter. That is, the filter unit 340 performs a filtering process of removing components above a predetermined frequency by applying a low-pass filter to the voltage value Vc. For example, the low-pass filter is a digital low-pass filter. The filter unit 340 outputs the filtered voltage value Vc to the differential calculation unit 350.

[0037] The differential calculation unit 350 generates time-series data of a differential value d by time-differentiating the voltage value Vc filtered by the filter unit 340. Then, the differential calculation unit 350 stores the generated time-series data of the differential value d in the storage unit 360. The differential value d in this embodiment is a first-order differential of the voltage value Vc (back electromotive force), but is not limited to this and may be a second-order or higher order differential.

[0038] Here, the differential calculation unit 350 generates a differential value d of the voltage value Vc during the period from the first time to a second time after a predetermined time ΔT has elapsed, and stores the generated differential value d in chronological order in the storage unit 360. For example, the first time is the current supply start time T1 or the current supply stop time T2. The predetermined time ΔT is a time that is sufficiently longer than the time from the first time until the fuel injector L closes, and is set in advance. The length of time (e.g., the number of digits) from the first time until the fuel injector L closes is known in advance through experiments or the like. Therefore, the predetermined time ΔT is set to be a time that is sufficiently longer than the valve closing time.

[0039] The storage unit 360 stores time-series data of the differential value d generated by the differential operation unit 350. That is, the storage unit 360 stores the differential value d generated by the differential operation unit 350 in chronological order. The time-series data stored in the storage unit 360 is data of the differential value d in chronological order from a first time to a second time. As an example, FIG. 3 shows time-series data stored in the storage unit 360. As shown in FIG. 3, the time-series data is data of differential values ​​d1 to dn at each time from t0, which is the first time, in chronological order, i.e., from t1, t2, t3, t4, t5, t6, ..., t(n-1), tn, in the order of time passage. Here, tn is the second time. Δt=(tn-t0).

[0040] The local maximum detection unit 370 reads the time series data stored in the storage unit 360 going back in the opposite direction (second direction) to the time series, and detects the local maximum time, which is the time when the differential value d changes from increasing to decreasing, and the differential value d at that local maximum time (hereinafter referred to as the "local maximum value"). That is, the local maximum detection unit 370 reads the time series data stored in the storage unit 360 going back in the opposite direction to the time series, and detects the local maximum point (local maximum time, local maximum value) when the differential value d changes from increasing to decreasing.

[0041] Here, tracing the time series data in the reverse direction to the chronological order means tracing the time series data from the second time to the first time. The time series refers to the direction in which time passes, namely, the first direction, which is the direction from the first time to the second time. The reverse direction of the time series refers to the direction opposite to the direction in which time passes, namely, the second direction, which is the direction from the second time to the first time. For example, in the example of time series data shown in FIG. 3, the local maximum detection unit 370 reads the differential values ​​d in the order of t(n-1), ..., t6, t5, t4, t3, t2, t1, t0, starting from the second time tn. That is, the local maximum detection unit 370 reads the differential values ​​d in the order of dn, d(n-1), ..., d6, d5, d4, d3, d2, d1, d0. Then, the local maximum detection unit 370 detects a local maximum point, which is an inflection point when the differential value d read from the second time point changes from increasing to decreasing.

[0042] When the local maximum detection unit 370 detects a local maximum point, the valve closing time detection unit 380 traces the differential value d back in the second direction from the local maximum point (local maximum time) and performs threshold determination processing to scan whether the decrease Δd of the differential value d from the local maximum value exceeds a predetermined threshold Δdth. When the determined decrease Δd exceeds the predetermined threshold Δdth, the valve closing time detection unit 380 determines the valve closing time of the fuel injector using the maximum time of the local maximum point at that time. For example, the valve closing time detection unit 380 scans from the local maximum point in the second direction, and when an event occurs in which the decrease Δd exceeds the predetermined threshold Δdth, it determines the maximum time of the local maximum point at that time as the valve closing time of the fuel injector L.

[0043] When multiple local maximum points are detected by the local maximum detection unit 370, the valve closing time detection unit 380 performs a threshold determination process for each local maximum point. Then, when the result of performing the threshold determination process for each local maximum point shows that there are multiple local maximum points (hereinafter referred to as "valve closing candidate points") where the decrease amount Δd exceeds a predetermined threshold Δdth, the valve closing time detection unit 380 may detect, as the valve closing time, the local maximum time of the valve closing candidate point that is the shortest time from the first time among the multiple valve closing candidate points.

[0044] Furthermore, when there are multiple candidate closing points, the valve closing time detection unit 380 may detect, as the valve closing time, the maximum time of the candidate closing point with the largest decrease amount among the multiple candidate closing points.

[0045] An example of a method for detecting the valve closing time according to this embodiment will be described with reference to FIG. 4. For example, the storage unit 360 stores time-series data from a first time t0 to a second time t18. The local maximum detection unit 370 reads the time-series data stored in the storage unit 360, going back from the second time t18, and sequentially scans the data to determine whether there is a local maximum point where the differential value d changes from increasing to decreasing. If the local maximum detection unit 370 detects a local maximum point, it outputs the local maximum point to the valve closing time detection unit 380. In the example of FIG. 4, the local maximum detection unit 370 detects point P10, which is time t10 and is indicated by the differential value d10, as the local maximum point.

[0046] The valve-closing time detection unit 380 traces back the time-series data in the second direction from time t10 of point P10, which is the local maximum point, and scans whether or not there is a derivative value d where the decrease Δd from the derivative value d10 (local maximum value) exceeds a predetermined threshold Δdth. In the example shown in Fig. 4, when tracing back the time-series data in the second direction from time t10 of point P10, which is the local maximum point, the decrease Δd (= d10 - d4) from the derivative value d10 (local maximum value) exceeds the predetermined threshold Δdth at point P4, so the valve-closing time detection unit 380 detects point P10, which is the local maximum point, as the valve-closing inflection point and t10, which is the local maximum time, as the valve-closing time.

[0047] When a local maximum point is detected by the local maximum detection unit 370, the valve closing time detection unit 380 may execute a condition determination process to determine whether at least one of the following first to third conditions is satisfied at the local maximum point. If at least one of the following first to third conditions is satisfied in the condition determination process, the valve closing time detection unit 380 determines that the maximum time of the local maximum point is not the valve closing time, and executes the condition determination process for the next local maximum point. If none of the following first to third conditions is satisfied in the condition determination process and the decrease amount Δd exceeds a predetermined threshold Δdth as a result of the threshold determination process, the valve closing time detection unit 380 determines the maximum time of the local maximum point as the valve closing time of the fuel injector.

[0048] (a) First condition: When tracing the differential value d back from the maximum point (maximum time) to the first time, the differential value d increases by a predetermined value dy or more. (b) Second condition: When the differential value d is traced back from the maximum point (maximum time) to the first time, the differential value d becomes equal to or greater than the maximum value of the maximum point. (c) Third condition: When tracing the differential value d from the maximum point (maximum time) back toward the first time, there is no decrease Δd that exceeds a predetermined threshold Δdth until a predetermined time has elapsed.

[0049] As an example of the first condition, when the time series data is traced back from the maximum point 10 toward the first time, if the differential value d increases and the amount of change from the differential value d5 at point P5 (point P5' shown in FIG. 4) to the differential value d4 at point P4 (point P4' shown in FIG. 4) becomes equal to or greater than a predetermined value dy, the valve closing time detection unit 380 excludes point P10, which is the maximum point, from the valve closing inflection point.

[0050] As an example of the second condition, when the time series data is traced back from the maximum point 10 toward the first time, if the differential value d increases and the differential value d4 at point P4 (point P4' shown in FIG. 4) becomes equal to or greater than the maximum value d10, the valve closing time detection unit 380 excludes point P10, which is the maximum point, from the valve closing inflection points.

[0051] As an example of the third condition, when the time series data is traced back from the maximum point P10 toward the first time, if there is no decrease Δd that exceeds a predetermined threshold Δdth before a predetermined time (for example, t10-t0) has elapsed (dash-dotted line in FIG. 4), the valve closing time detection unit 380 excludes the maximum point P10 from the valve closing inflection point.

[0052] The correction unit 390 corrects the power-on time Ti according to the valve-closing time obtained by the valve-closing time detection unit 380. For example, the correction unit 390 corrects the power-on time Ti so that the valve-closing time becomes a target value. As an example, the correction unit 390 corrects the power-on time Ti by adjusting the power-off time so that the difference between the valve-closing time and the target value is eliminated.

[0053] An example of the flow of operations of the control device 300 will be described below with reference to FIG. When opening the fuel injection valve L, the control device 30 starts energizing the solenoid coil 4 at a preset energization start time T1, and then stops energizing the solenoid coil 4 at an energization stop time T2 after the energization time Ti has elapsed (step S101).

[0054] The control unit 320 performs time differentiation on the voltage value Vc from a first time after the power supply to the solenoid coil 4 is stopped in a first direction, and generates a differential value d of the voltage value Vc (step S102). Then, the control unit 320 stores the generated differential value d of the voltage value Vc in the storage unit 360, thereby storing time-series data of the differential value d from the first time to the second time (step S103).

[0055] The control unit 320 reads the time-series data stored in the storage unit 360 going back from the second time in the second direction, and scans for a local maximum point where the differential value d changes from increasing to decreasing (step S104). The control unit 320 then determines whether a local maximum point has been detected (step S105). If the control unit 320 determines that a local maximum point has been detected, the control unit 320 sets the local maximum point as a reference point (step S106). The control unit 320 selects, as the target differential value, a differential value at a time point going back a certain time (e.g., the sampling time of the differential value d) from the reference point in the time-series data (step S107). For example, if the control unit 320 sets the reference point in the time-series data to point Pn-1, which is a certain time point going back from the reference point in the second direction, as the target differential value.

[0056] The control unit 320 calculates the decrease Δd from the differential value d at the reference point to the target differential value (step S108), and performs a threshold determination process to determine whether the calculated decrease Δd exceeds a predetermined threshold Δdth (step S109). If the decrease Δd exceeds the predetermined threshold Δdth, the control unit 320 determines the current reference point as the valve-closing inflection point (step S110). That is, if the decrease Δd exceeds the predetermined threshold Δdth, the control unit 320 determines the time (maximum time) of the current reference point as the valve-closing time.

[0057] In step S109, if the decrease amount Δd does not exceed the predetermined threshold value Δdth, the control unit 320 determines whether any one of the first to third conditions is satisfied (step S111). If any one of the first to third conditions is satisfied, the control unit 320 again reads back from the current reference point in the second direction and scans for a maximum point where the differential value d changes from increasing to decreasing (step S112). Then, the control unit 320 returns to step S105 and determines whether a maximum point has been detected. If it is determined that a maximum point has been detected, the control unit 320 clears the current reference point and sets the newly detected maximum point as the reference point. Then, the control unit 320 proceeds to step S107.

[0058] If none of the first to third conditions is satisfied in step S111, the control unit 320 selects a differential value obtained by going back a certain time in the second direction from the target differential value as a new target differential value (step S113).Then, the control unit 320 proceeds to step S108.

[0059] The effects of this embodiment will be described below with reference to FIG. 6 . When the valve is closed, the movable core 10 descends, and at the timing when the fuel injection valve L closes, the valve element 6 collides with the valve seat 3, causing the movable core 10 to separate from the retainer. This changes the acceleration of the movable core 10, which in turn changes the magnetic flux in the magnetic path and causes a change in the back electromotive force. As a result, a first inflection point H1 occurs in the differential value d of the back electromotive force. This first inflection point H1 is the valve-closing inflection point. However, after the valve is closed, the descent speed of the movable core 10 slows due to the reverberation of fuel pressure and the bouncing of the valve element 6, causing a change in the back electromotive force. This causes a second inflection point H2 in the differential value d after the inflection point H1. This inflection point H2 is not the inflection point H1 caused by the valve closing. Therefore, the valve closing time detection unit 380 detects the closing of the fuel injection valve L by detecting the first inflection point H1, not the second inflection point H1.

[0060] One example is a method in which the time-series data of the differential value d is scanned in a first direction for local maximum values, and when the decrease Δd from the local maximum value exceeds a predetermined threshold Δdth, the local maximum value is detected as a valve-closing inflection point. With this method, as shown in FIG. 6, the decrease Δd from the initially detected local maximum value may not exceed the predetermined threshold Δdth. As a result, the first inflection point H1 may not be detected. On the other hand, the control device 300 of this embodiment scans the time-series data of the differential value d in a second direction instead of the first direction, and when the decrease Δd from the local maximum value exceeds the predetermined threshold Δdth, the local maximum value is detected as a valve-closing inflection point. Here, the decrease Δd may not exceed the predetermined threshold Δdth in the first direction, but it is impossible for the decrease Δd to not exceed the predetermined threshold Δdth in the second direction. This is because in the second direction, no local maximum occurs after the inflection point H1, and the differential value d after the inflection point H1 converges to zero, thereby enabling the control device 300 of this embodiment to reliably detect the valve-closing inflection point.

[0061] Although an embodiment of the present invention has been described above in detail with reference to the drawings, the specific configuration is not limited to this embodiment, and includes designs within the scope of the gist of the present invention.

[0062] The control device 300 of the above embodiment executes a determination process of tracing back the time-series data from the local maximum point in the second direction to scan whether or not the decrease Δd of the differential value d from the local maximum point exceeds a predetermined threshold Δdth, and if an event occurs in which the decrease Δd exceeds the predetermined threshold Δdth, detects the local maximum time, which is the time of the local maximum point, as the valve closing time of the fuel injection valve L. This makes it possible to reliably detect the valve closing inflection point.

[0063] The control device 300 may detect local maxima by the local maximum detection unit 370 by tracing back the time-series data from the second time to the first time, and if the local maximum detection unit 370 detects multiple local maxima, it may execute a determination process for each local maximum, and if there are multiple candidate valve-closing points that are local maxima when it is determined as a result of the determination process that an event exists in which the decrease Δd exceeds a predetermined threshold Δdth, it may detect the shortest maximum time among the candidate valve-closing points as the valve-closing time. This makes it possible to suppress erroneous detection of a valve-closing inflection point.

[0064] The control device 300 may detect local maxima by the local maximum detection unit 370 by tracing back the time-series data from the second time to the first time, and if the local maximum detection unit 370 detects multiple local maxima, it may execute a determination process for each local maximum, and if there are multiple candidate closing valve points that are local maxima when it is determined as a result of the determination process that an event exists in which the decrease Δd exceeds a predetermined threshold Δdth, it may detect the maximum time of the candidate closing valve point with the largest decrease Δd among the candidate closing valve points as the valve closing time. This makes it possible to suppress erroneous detection of a valve closing inflection point. [Explanation of symbols]

[0065] L... fuel injection valve, 1... solenoid valve driving device, 300... control device, 310... voltage detection unit, 320... control unit, 350... differential calculation unit, 360... storage unit, 370... maximum detection unit, 380... valve closing time detection unit

Claims

1. A control device for controlling energization of a fuel injection valve in which a valve element is opened by separating from a valve seat in response to a magnetic force generated by energizing a solenoid coil, and the valve element is closed by contacting the valve seat in response to a resilient force of a valve element biasing spring when energization to the solenoid coil is stopped, a voltage detection unit that divides a predetermined time ΔT, which is set from a first time when current supply to the solenoid coil is started or stopped to a second time when the predetermined time ΔT has elapsed, the predetermined time ΔT being set to be a time sufficiently longer than a known time until the fuel injection valve closes, by a sampling time having a cycle shorter than the predetermined time ΔT, and detects a back electromotive force generated in the solenoid coil every time the sampling time is divided; a differential value calculation unit that calculates a second-order differential value obtained by second-order time differentiation of the back electromotive force detected by the voltage detection unit; a storage unit that stores the second-order differential values ​​as time-series data, the second-order differential values ​​being represented in a format in which a number n (n is a positive integer) that is incremented in the order in which the back electromotive voltages that are the calculation source data are detected by the voltage detection unit, i.e., in the order in which time elapses, is assigned to the second-order differential values; a maximum detection unit that sequentially scans the time-series data of the second-order differential value in a direction from the second time point where the number n is maximum to the first time point where the number n is minimum, and detects, as a maximum point, the second-order differential value that corresponds to an extreme value when the second-order differential value changes from increasing to decreasing; a valve closing time detection unit that sequentially scans time series data of second-order differential values ​​in a direction from the maximum point toward the first time, sequentially selects target second-order differential values ​​from the time series data of second-order differential values, executes a determination process to determine whether or not a decrease in second-order differential value, which is a difference between the maximum point and the target second-order differential value, exceeds a predetermined threshold, and when it is determined that the decrease in second-order differential value exceeds the predetermined threshold, calculates a maximum time, which is an integrated time of the sampling times from the first time to the maximum point, and sets this maximum time as a valve closing time of the fuel injection valve, When a plurality of local maximum points are detected by the local maximum detection unit, the valve closing time detection unit executes the determination process for each of the plurality of local maximum points, and when it is determined as a result of the determination process that the amount of decrease in the second-order derivative from the local maximum point exceeds the predetermined threshold, the valve closing time detection unit calculates a local maximum time candidate which is an integrated time of the sampling times from the first time to the local maximum point, and when a plurality of local maximum time candidates have been calculated, the control device sets the value of the local maximum time candidate which is the shortest time from the first time among the plurality of local maximum time candidates as the local maximum time and the valve closing time.

2. A control device for controlling energization of a fuel injection valve in which a valve element is opened by separating from a valve seat in response to a magnetic force generated by energizing a solenoid coil, and the valve element is closed by contacting the valve seat in response to a resilient force of a valve element biasing spring when energization to the solenoid coil is stopped, a voltage detection unit that divides a predetermined time ΔT, which is set from a first time when current supply to the solenoid coil is started or stopped to a second time when the predetermined time ΔT has elapsed, the predetermined time ΔT being set to be a time sufficiently longer than a known time until the fuel injection valve closes, by a sampling time having a cycle shorter than the predetermined time ΔT, and detects a back electromotive force generated in the solenoid coil every time the sampling time is divided; a differential value calculation unit that calculates a second-order differential value obtained by second-order time differentiation of the back electromotive force detected by the voltage detection unit; a storage unit that stores the second-order differential values ​​as time-series data, the second-order differential values ​​being represented in a format in which a number n (n is a positive integer) that is incremented in the order in which the back electromotive voltages that are the calculation source data are detected by the voltage detection unit, i.e., in the order in which time passes, is assigned to the second-order differential values; a maximum detection unit that sequentially scans the time-series data of the second-order differential value in a direction from the second time point where the number n is maximum to the first time point where the number n is minimum, and detects, as a maximum point, the second-order differential value that corresponds to an extreme value when the second-order differential value changes from increasing to decreasing; a valve closing time detection unit that sequentially scans time series data of second-order derivatives in a direction from the maximum point toward the first time to sequentially select target second-order derivatives from the time series data of second-order derivatives, executes a determination process to determine whether or not a second-order derivative decrease amount Δdth, which is a difference between the maximum point and the target second-order derivative, exceeds a predetermined threshold, and when it is determined that the second-order derivative decrease amount Δdth exceeds the predetermined threshold, calculates a maximum time, which is an integrated time of the sampling times from the first time to the maximum point, and sets this maximum time as a valve closing time of the fuel injection valve, the valve-closing time detection unit, when a plurality of local maximum points are detected by the local maximum detection unit, executes the determination process for each of the plurality of local maximum points, and when it is determined as a result of the determination process that the amount of decrease in the second-order differential value from the local maximum point exceeds the predetermined threshold, sets the local maximum point corresponding to the determination as a valve-closing candidate point; When a plurality of the valve closing candidate points are set, a maximum time is calculated, which is an integrated time of the sampling times from the valve closing candidate point with the largest decrease in the second-order derivative among the plurality of the valve closing candidate points to the first time point, and the valve closing time detection unit determines the maximum time as the valve closing time of the fuel injection valve.

3. a correction unit that calculates a target valve closing time value and corrects a power supply time to the solenoid coil so that the valve closing time calculated by the valve closing time detection unit becomes the target valve closing time value, The control device according to claim 1 or 2.

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