JP6445927B2 - Control device for fuel injection valve - Google Patents

Description

  The present invention relates to a control device for a fuel injection valve. More specifically, the present invention relates to a control device for a fuel injection valve used in an internal combustion engine.

  As a control device for a fuel injection valve used in an internal combustion engine, in recent years, what performs so-called multistage injection control in which fuel is injected in a plurality of times during one cycle has become mainstream. By performing multi-stage injection control, combustion with high efficiency and low emission can be realized. Under this multi-stage injection control, since the opening and closing of the valve body is repeated in a short time, it is required to accurately control the timing for opening and closing the valve body. In order to accurately control the opening / closing timing of the valve body, it is preferable to estimate whether or not the valve body has been seated at an appropriate timing, and more preferably to estimate the timing at which the valve body has been seated.

  Patent Document 1 discloses a technique for estimating the time when a valve element is seated on a valve seat using a detection signal of a solenoid terminal voltage of an electromagnetic valve. In the invention of Patent Document 1, the seating timing of the solenoid valve seating is estimated by using a characteristic inflection point in the voltage change characteristic of the solenoid immediately after the drive current is cut off.

JP 2014-234922 A

  By the way, in the invention of Patent Document 1, it is assumed that the inflection point occurs due to the maximum rate of change of acceleration of the valve body when the electromagnetic valve is seated, and the peak rate of change of acceleration occurs. In order to detect this timing, the detection signal of the terminal voltage is subjected to band-pass filter processing corresponding to second-order differentiation. However, since the change that occurs in the solenoid terminal voltage at the inflection point is actually very small and is susceptible to noise because it undergoes the calculation of the second derivative, in the invention of Patent Document 1, It is difficult to accurately determine the seating of the solenoid valve.

  An object of the present invention is to provide a control device for a fuel injection valve that can accurately determine whether or not a valve body included in the fuel injection valve is seated.

  (1) The present invention closes an electromagnetic actuator (for example, an electromagnetic actuator 45 described later) that generates an electromagnetic force when energized and biases a valve body (for example, a valve body 41a described later) to the valve opening side, and the valve body. A control device (for example, an ECU 6 described later) for a fuel injection valve (for example, an after-mentioned fuel injection valve 4) having a spring (for example, an after-mentioned spring 43) urging to the valve side, and a predetermined valve opening command period The drive current control means (for example, a solenoid drive circuit 61 and a CPU 65 described later) for controlling the drive current of the electromagnetic actuator to 0 or more and the drive current control means stop energizing the electromagnetic actuator. Seating determination means (for example, a CPU 65 described later) for determining whether or not the valve body is seated based on a waveform of a back electromotive voltage, and the drive current control Stage, just before the opening command period ends is characterized by increasing the drive current from the hold current is determined so as to maintain the open state of the valve body.

  (2) In this case, the control device further includes a power source (for example, a battery described later) and a switching element (for example, a Hi-side switching element 611 described later) that intermittently connects the power source and the electromagnetic actuator. Preferably, the drive current control means raises the drive current from the hold current by increasing an on / off ratio of the switching element.

  (3) In this case, the control device further includes a first power supply (for example, a battery described later) and a second power supply (for example, a booster circuit 62 described later) having a voltage higher than that of the first power supply. The drive current control means preferably raises the drive current from the hold current by switching a power source connected to the electromagnetic actuator from the first power source to the second power source.

  (1) When energization of the electromagnetic actuator is stopped, the valve element is urged by the elastic force of the spring and moves to the valve closing side. At this time, an induced voltage (hereinafter referred to as “back electromotive voltage”) having a polarity opposite to that of the applied voltage when energized is generated in the electromagnetic actuator. The counter electromotive voltage decreases asymptotically toward 0 after rapidly decreasing from the peak immediately after the energization stop as the valve body moves toward the valve closing side, but the rate of decrease is not monotonous. More specifically, the rate of decrease in the back electromotive force once becomes slightly gentle due to a change in magnetic flux density and then becomes abrupt again in the vicinity where the valve element is seated on the valve seat and its movement stops. In other words, in the vicinity where the actual valve body is seated, the counter electromotive voltage behaves slightly convex toward the direction of generation. Therefore, the presence or absence of seating of the valve element can be determined by specifying a slight convex behavior from the back electromotive force waveform. In the present invention, by increasing the drive current value from the hold current value immediately before the valve opening command period ends, the back electromotive voltage generated after the valve opening command period ends and energization is stopped can be increased. . Further, this makes it possible to emphasize the convex behavior in the back electromotive voltage waveform, and as a result, the presence or absence of seating of the valve body can be accurately determined.

  (2) In the present invention, immediately before the end of the valve opening command period, the ON / OFF ratio of the switching element that intermittently connects the electromagnetic actuator and the power source is increased. As a result, the drive current can be easily increased from the hold current.

  (3) In the present invention, immediately before the valve opening command period ends, the power source connected to the electromagnetic actuator is switched from the first power source to the second power source having a higher voltage. As a result, the drive current can be easily increased from the hold current.

It is a figure which shows the structure of the fuel-injection system which concerns on one Embodiment of this invention, and its control apparatus. It is a figure which shows the structure of a fuel injection valve. It is a figure which shows the structure of the circuit which supplies a drive current to a solenoid among ECU. It is a figure which shows an example of the waveform of the solenoid electric current and monitoring voltage at the time of the valve opening operation | movement of a fuel injection valve, and a valve closing operation | movement. It is a flowchart which shows the procedure of fuel-injection control. 6 is a flowchart showing a procedure of fuel injection control (continuation of FIG. 5). It is a figure which shows typically an example of the voltage and electric current waveform implement | achieved by fuel-injection control. It is a figure for demonstrating the process which produces | generates an interpolation line. It is a figure for demonstrating the process which calculates a difference value and an area value. It is a figure which shows typically an example of the voltage and current waveform in the modification of the said embodiment.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram showing a configuration of a fuel injection system S according to the present embodiment and an ECU 6 as a control device thereof. The fuel injection system S includes a fuel tank 2, a high-pressure fuel pump 5, a delivery pipe 3, and a plurality of fuel injection valves 4.

  The fuel tank 2 stores fuel supplied from the outside. The fuel tank 2 is provided with a fuel pump unit 21 that pumps fuel to the high-pressure fuel pump 5. The high-pressure fuel pump 5 further compresses the fuel pumped from the fuel pump unit 21 using the power generated in the engine 1 and supplies the compressed fuel to the delivery pipe 3.

  The delivery pipe 3 stores the high-pressure fuel discharged from the high-pressure fuel pump 5. The fuel injection valve 4 is provided for each of a plurality of cylinders of the engine 1. These fuel injection valves 4 are connected to the delivery pipe 3 via the fuel supply pipe 31. The ECU 6 executes the fuel injection control described later, thereby performing the fuel injection valve 4 at an appropriate timing according to the operating state of the engine 1 acquired based on the outputs of various sensors such as the crank angle sensor 91 and the fuel pressure sensor 92. The high pressure fuel in the delivery pipe 3 is directly injected into each cylinder of the engine 1.

  FIG. 2 is a diagram showing the configuration of the fuel injection valve 4. FIG. 2 shows a state when the fuel injection valve 4 is closed.

  The fuel injection valve 4 includes a rod-shaped rod 41 provided with a valve body 41a on the distal end side and a movable core 41b on the proximal end side, a valve seat 42 on which the valve body 41a is seated, and a proximal end side of the rod 41 The spring 43 that biases the rod 41 toward the valve closing side (the direction in which the valve body 41a is seated on the valve seat 42) is provided by the elastic force, and the rod 41 is opened by the electromagnetic force provided on the proximal end side of the rod 41. And an electromagnetic actuator 45 that biases the valve body 41a (the direction in which the valve body 41a is separated from the valve seat 42).

  The electromagnetic actuator 45 includes a cylindrical solenoid L provided coaxially with the rod 41 and a core sleeve 46 inserted into the solenoid L. The core sleeve 46 is provided on the proximal end side of the movable core 41b. The core sleeve 46 has a cylindrical shape, and when the valve body 41a is separated from the valve seat 42, the fuel flows through the center from the proximal end side toward the distal end side. Further, the main body (not shown) that houses the electromagnetic actuator 45 is in contact with a non-regulating member 41c provided on the rod 41, thereby restricting the movement of the rod 41 toward the valve opening side. A regulating member 47 that maintains the valve open state is provided.

A procedure for driving the fuel injection valve 4 will be described.
First, in a state where energization to the solenoid L is stopped, the rod 41 is biased toward the valve closing side by the elastic force of the spring 43, so that the valve element 41a is maintained in the valve closing state in which the valve element 41a is seated on the valve seat 42. . In the closed state, fuel injection is stopped.
When a drive current is supplied to the solenoid L from the valve closed state, the movable core 41b is drawn toward the core sleeve 46 by the electromagnetic force generated by the solenoid L. As a result, the rod 41 moves to the valve opening side, and the valve body 41a is separated from the valve seat 42. When the non-regulating member 41c provided on the rod 41 comes into contact with the regulating member 47, the movement of the rod 41 is stopped, thereby opening the valve. In the open state, fuel is injected.
Further, when energization to the solenoid L is stopped from the valve open state, the rod 41 is urged toward the valve closing side by the elastic force of the spring 43 and returns to the valve closed state.

  FIG. 3 is a diagram showing a configuration of a circuit for supplying a drive current to the solenoid L in the ECU 6. FIG. 3 shows only the circuit configuration relating to one fuel injection valve among the plurality of fuel injection valves provided for each cylinder, and the circuit configuration relating to the other fuel injection valves is omitted. The ECU 6 includes a solenoid drive circuit 61, a booster circuit 62, a voltage monitoring circuit 63, and a CPU 65.

  The booster circuit 62 is configured by combining a booster coil 621, a switching element 622, a backflow prevention diode 623, capacitors 624 and 625, and a logic circuit 626. The booster circuit 62 boosts an output voltage VBAT (for example, 13 V) of a battery (not shown) by combining the functions of these elements, and outputs a boosted voltage VBST. In the booster circuit 62, when the drain-source of the switching element 622 is energized / cut off under a predetermined switching frequency by a signal output from the logic circuit 626 based on a control signal from the CPU 65, the output voltage of the battery VBAT is boosted via the boost coil 621. The boosted voltage VBST is applied to the capacitor 625, whereby the capacitor 625 is charged. The CPU 65 turns on / off the switching element 622 so that the boosted voltage VBST is maintained at a predetermined magnitude (for example, 40 V).

  The solenoid drive circuit 61 includes two Hi-side switching elements 611 and 612 provided on one end side of the solenoid L (more specifically, a high potential side close to the battery and the booster circuit 62), and the other end side of the solenoid L. (More specifically, a low-side switching element 613 provided on the low potential side close to the ground), a reflux diode 614 for flowing a surge current generated when energization of the solenoid L is stopped, and a solenoid L A current monitoring resistor 615 for monitoring the drive current to the circuit, a Zener diode 616 for absorbing the surge voltage, and a logic circuit 617 for turning on or off each of the switching elements 611 to 613 based on a control signal from the CPU 65. And comprising.

  The Hi-side switching element 611 is provided in the energization path from the battery to one end side of the solenoid L. When the output signal from the logic circuit 617 to the gate is turned on, the Hi-side switching element 611 connects the battery and the solenoid L, and applies the battery output voltage VBAT to the solenoid L. The Hi-side switching element 612 is provided in the energization path from the booster circuit 62 to one end side of the solenoid L. When the output signal from the logic circuit 617 to the gate is turned on, the Hi-side switching element 612 connects the booster circuit 62 and the solenoid L, and applies the boosted voltage VBST of the booster circuit 62 to the solenoid L. Further, the Lo-side switching element 613 is provided in an energization path from the other end side of the solenoid L to the ground. When the output signal from the logic circuit 617 is turned on, the Lo side switching element 613 connects the solenoid L and the ground and starts energizing the solenoid 553. Further, when the output signal from the logic circuit 617 is turned off, the Lo-side switching element 613 cuts off the solenoid L and the ground and stops energizing the solenoid L.

  The current monitoring resistor 615 is provided between the Lo-side switching element 613 in the energization path of the solenoid L and the ground. The CPU 65 detects the current flowing through the current monitoring resistor 615 by using the voltage across the current monitoring resistor 615. Here, the magnitude of the current flowing through the solenoid L while the Lo-side switching element 613 is turned on is equal to the magnitude of the current flowing through the current monitoring resistor 615. Hereinafter, the current detected by the CPU 65 and flowing through the current monitoring resistor 615 is also referred to as solenoid current IINJ.

  The voltage monitoring circuit 63 is configured by combining a diode 631, voltage monitoring resistors 632 and 633, and an RC filter circuit 634. The RC filter circuit 634 is configured by combining a resistance element 635 and a capacitor 636, and removes high frequency noise included in the voltage across the voltage monitoring resistor 632. The CPU 65 detects the voltage across the voltage monitoring resistor 632 via the RC filter circuit 634. The voltage across the voltage monitoring resistor 632 shows the same change qualitatively as the voltage across the solenoid L. Hereinafter, the voltage detected by the CPU 65 and the voltage across the voltage monitoring resistor 632 is also referred to as a monitoring voltage VMON of the solenoid L.

  The CPU 65 turns the switching elements 611 to 613 on or off according to the procedure of fuel injection control (see FIGS. 5 and 6) described later using the solenoid current IINJ and the monitoring voltage VMON detected as described above. The fuel injection amount from the fuel injection valve is controlled.

Next, a specific operation example of the fuel injection valve will be described with reference to FIG.
FIG. 4 is a diagram illustrating an example of waveforms of the solenoid current IINJ (broken line) and the monitoring voltage VMON (thick line) during the opening and closing operations of the fuel injection valve. In the example of FIG. 4, at time t0, a valve opening command for changing the fuel injection valve from the closed state to the valve opening state is generated, and at time t2, a valve closing command for changing the fuel injection valve from the valve opening state to the valve closing state is issued. Indicates when it occurred.

  First, at time t0, the CPU turns on the Lo-side switching element and the Hi-side switching element in response to the fuel injection valve opening command being generated, and starts supplying drive current to the solenoid (described later). Overexcitation control). Here, the CPU immediately turns on the Hi-side switching element 612 in FIG. 3 to turn on the solenoid so that the valve body is quickly separated from the elastic force of the spring and the pressure of the fuel immediately after the supply of the drive current is started. Applies the boosted voltage VBST of the booster circuit. As a result, the monitoring voltage VMON decreases from 0 [V] to the negative side, and the solenoid current IINJ quickly increases and shifts to the valve opening state.

  At time t1, the CPU turns off the Hi-side switching element 612 in FIG. 3 and switches the Hi-side switching so as to maintain the valve-closed state with as little energy as possible in response to the fuel injection valve shifting to the valve-opening state. The element 611 is turned on, and the battery output voltage VBAT is applied to the solenoid (hold control described later). As a result, the monitoring voltage VMON increases to the vicinity of 0 [V] and the solenoid current IINJ also starts to decrease. At this time, the CPU is determined to turn on / off the Hi-side switching element 611 at a predetermined duty ratio so that the connection between the solenoid and the battery is interrupted and the solenoid current IINJ is maintained in the closed state. A predetermined hold current is maintained. Thereby, the valve open state is maintained after time t1.

  Next, at time t2, the CPU turns off the Lo-side switching element and the Hi-side switching element in response to the occurrence of the fuel injection valve closing command, and stops the supply of drive current to the solenoid. Then, it is estimated that the valve body is biased toward the valve closing side by the elastic force of the spring and is seated on the valve seat in the vicinity of time t3 in FIG. As a result, the fuel injection valve shifts to a closed state. At this time, a counter electromotive voltage having a polarity opposite to the applied voltage at the time of energization is generated in the solenoid. Therefore, when the supply of drive current to the solenoid is stopped, the monitoring voltage VMON of the solenoid once greatly fluctuates in the direction opposite to that at the time of supply of drive current as shown in FIG. As it moves to the side, it gradually decreases and becomes approximately 0 [V] at time t4.

  As shown in FIG. 4, the monitoring voltage VMON becomes maximum immediately after the supply of the drive current is stopped at time t2, and thereafter decreases almost asymptotically to 0 [V]. That is, the decrease rate of the monitoring voltage VMON becomes maximum at time t2, and thereafter gradually decreases at a predetermined rate, but the change is not monotonous. In the vicinity of time t3 when the valve body is estimated to be seated on the valve seat, as shown by a broken line in FIG. 4, the rate of decrease in the monitoring voltage VMON once becomes slightly gentle due to the change in magnetic flux density. It becomes steep again. As a result, the monitoring voltage VMON behaves slightly convex toward the direction of generation of the counter electromotive voltage in the vicinity of time t3. Below, the specific procedure of the fuel injection control using the correlation between the convex behavior of the monitoring voltage VMON and the seating of the valve body will be described.

5 and 6 are flowcharts showing the procedure of fuel injection control by the CPU. The processing in FIGS. 5 and 6 is executed by the CPU at every predetermined period in which fuel is injected from the fuel injection valve.
FIG. 7 is a diagram schematically illustrating an example of voltage and current waveforms realized by fuel injection control. The upper voltage waveform in FIG. 7 shows the waveform of the voltage across the solenoid, and the lower current waveform shows the waveform of the solenoid drive current. In FIG. 7, the illustration of fluctuations in the voltage across the solenoid caused by switching on / off of the switching element is omitted.

  First, in S1, the CPU sets a valve opening command period and an injection start command time in the current fuel injection, and proceeds to S2. The valve opening command period corresponds to the time from when the fuel injection valve opening command is generated until the valve closing command is generated, in other words, the time during which the supply of drive current to the solenoid is continuously commanded. The injection start command time corresponds to the time when the valve opening command is generated. The injection stop command time for commanding the stop of the supply of drive current to the solenoid of the fuel injection valve is obtained by matching the valve opening command period with the injection start command time.

  In S2, the CPU sets a hold start time and a re-overexcitation start time corresponding to the time for instructing the start of hold control (S6) and re-excitation control (S8) described later, and proceeds to S3. Here, the hold start time is between the injection start command time and the injection stop command time, and more specifically, when the overexcitation control (S4) described later is executed from the injection start command time, the valve is closed. Is set to a time at which it can be determined that the valve has surely shifted to the valve open state. The re-excitation start time is between the hold start time and the injection stop command time, and is set immediately before the injection stop command time.

  In S3, the CPU determines whether or not the injection start command time has been reached. If the determination in S3 is NO, the process waits until the injection start command time is reached. If the determination in S3 is YES, the process proceeds to S4 and overexcitation control is executed. In this overexcitation control, the CPU connects the booster circuit and the solenoid and applies the boosted voltage VBST to the solenoid. Thereby, as shown in FIG. 7, the drive current of the solenoid quickly rises, and the fuel injection valve quickly shifts to the valve open state.

  In S5, the CPU determines whether or not the hold start time has been reached, that is, whether or not the fuel injection valve has surely shifted to the valve opening state. If the determination in S5 is NO, the overexcitation control (S4) is executed until the hold start time is reached, and if the determination in S4 is YES, the process proceeds to S6 and the hold control is executed. In this hold control, the CPU connects a battery and a solenoid, and applies a battery voltage VBAT lower than the boosted voltage VBST to the solenoid. Thereby, as shown in FIG. 7, the drive current of the solenoid quickly decreases. Further, in this hold control, the CPU performs a battery and solenoid operation under a predetermined duty ratio (on / off ratio) so that the solenoid drive current becomes a hold current set in advance so as to maintain the valve open state. The Hi-side switching element 611 (see FIG. 3) that connects between the two is intermittently connected.

  In S7, the CPU determines whether or not the re-excitation start time has been reached, that is, whether or not the valve opening command period has been reached. If the determination in S7 is NO, hold control (S6) is executed until the re-excitation start time is reached, and if the determination in S7 is YES, the process proceeds to S8 and re-excitation control is executed. In this re-overexcitation control, the CPU increases the duty ratio of the Hi-side switching element 611 as compared with the hold control. Thereby, as shown in FIG. 7, the drive current of the solenoid is higher than the hold current of S6.

  In S9, the CPU determines whether or not the injection stop command time has been reached. If the determination in S9 is NO, re-excitation control (S8) is executed until the injection stop command time is reached, and if the determination in S9 is YES, the supply of drive current to the solenoid is stopped (S10). ), Go to S11.

  Here, the effect of executing re-overexcitation control (S9) immediately before the valve opening command period ends will be described. As shown in FIG. 7, when the supply of the drive current to the solenoid is stopped, an electromotive voltage having a polarity opposite to that at the time of supplying the drive current is generated in the solenoid. In FIG. 7, the voltage and current waveforms when the re-excitation control is not performed are indicated by broken lines. Since this counter electromotive voltage is generated so as to prevent the drive current from decreasing, the counter electromotive voltage generated immediately after the drive current is stopped increases as the drive current immediately before the supply is stopped is increased. For this reason, since the change in the back electromotive voltage becomes large, the convex behavior of the monitoring voltage is emphasized, and as a result, the accuracy of determining the presence or absence of seating of the valve body can be improved.

  Returning to the description of FIG. 6, in S11 and S12, after stopping the supply of the drive current, the CPU sets the value of the monitoring voltage VMON correlated with the counter electromotive voltage generated in the solenoid for each predetermined sampling period Ts. A predetermined maximum number of sampling times Nmax is acquired, and the acquired Nmax sampling values are stored in a predetermined buffer. In the following, the sampling value of the monitoring voltage VMON for the nth time (hereinafter, “n” is an integer from 1 to Nmax), in other words, the sampling value after (Ts × n) hours from the injection stop command time. Indicated as “VMON (n)”. Hereinafter, the injection stop command time is set to 0, and the sampling time at which the nth sampling value VMON (n) is acquired is expressed as “t_n” (t_n = n × Ts). Further, in the following calculation using the sampling value acquired here, a physical quantity having a time dimension is discretized under the period Ts. Here, the maximum sampling number Nmax is an integer of 2 or more. The period for sampling the value of the monitoring voltage VMON (Ts × Nmax) is set to sufficiently include the period from the injection stop command time to the time when the value of the monitoring voltage VMON can be determined to be almost zero.

  In S13, the CPU sets an estimated seating period having a predetermined width including the time when it is estimated that the valve element is seated on the valve seat after the supply of the drive current is stopped, and the process proceeds to S14. More specifically, in S13, a start period t_ns that specifies the start time of the estimated seating period and an end period t_ne that specifies the end time are set. As shown in FIG. 8, this estimated seating period is preferably set so as to include a period in which the rate of decrease in the monitoring voltage VMON once becomes gradual after the energization to the solenoid is stopped. If the fuel injection valve is in a normal state, the time at which such a period occurs is generally constant. Therefore, the start t_ns and the end t_ne of the estimated seating period as described above are specified by conducting an experiment in advance. be able to.

  In addition, in S13, for example, by performing the following processing on the plurality of sampling values VMON (n) acquired in S11 and S12, the start t_ns of the estimated seating period so that the period of the monitoring voltage is surely included. And the end t_ne may be set. In this case, the start t_ns of the estimated seating period is the differential value of the sampling value (V ′ (n) = VMON (n + 1) −VMON (n)) in order from the sampling start time side (left side in FIG. 8), that is, the monitoring voltage. A value corresponding to the decrease rate is calculated, and the time when this differential value V ′ (n) becomes larger than a predetermined negative threshold value for the first time. Further, the end t_ne of the estimated seating period is the time when the differential value of the sampling value is calculated in order from the sampling end time side (right side in FIG. 8), and this differential value becomes smaller than a predetermined negative threshold value for the first time.

  In S14, the CPU generates an interpolation line that passes through the estimated seating period by using one of the plurality of sampling values VMON (n) that belongs to the period outside the estimated seating period, and proceeds to S15. Hereinafter, a specific procedure for generating an interpolation line will be described with reference to FIG.

  First, at least one of a plurality of sampling values VMON (n) belonging to a period before the estimated seating period and closest to the start period t_ns of the estimated seating period, and an estimated seating of the plurality of sampling values VMON (n) At least one that belongs to a period after the period and is closest to the end t_ne of the estimated seating period is extracted. Hereinafter, as shown by black circles in FIG. 8, a case where sampling values VMON (na) and VMON (nb) are extracted one by one from before and after the estimated seating period will be described.

  Next, by using the sampling values (VMON (na), VMON (nb)) extracted from before and after the estimated seating period and the time (t_na, t_nb), the estimated seating period within the estimated seating period shown in FIG. Generate an interpolation line that passes through. More specifically, a first-order approximate straight line that passes through both of these extracted sampling values is specified, and this is used as an interpolation line. When two or more sampled values are extracted before and after the estimated seating period, a first-order approximate straight line passing through the vicinity of the plurality of sampled values is specified by a method such as a least square method, Is an interpolation line.

  As described with reference to FIG. 4, when the fuel injection valve is normal, the rate of decrease of the monitoring voltage once becomes moderate and then abrupt again inside the estimated seating period. For this reason, as shown in FIG. 8, if the direction in which the back electromotive voltage is generated is positive, the sampling value within the estimated seating period is almost equal to the interpolation line generated using the monitoring voltage outside the estimated seating period. Everything gets bigger.

  Returning to the description of FIG. 6, in S15, the CPU starts from a plurality of sampling values VMON (i) (hereinafter, “i” is an integer from na to nb) belonging to the estimated seating period. By subtracting the value of the interpolation line, a plurality of difference values Δ (i) as shown in FIG. 9 are calculated. The difference value Δ (i) indicates the fluctuation of the monitoring voltage with reference to the interpolation line as shown in FIG. In S16, the CPU calculates the sum of the products of the difference value Δ (i) and the sampling period Ts over the estimated seating period, that is, the area value S between the sampling value of the monitoring voltage and the interpolation line within the estimated seating period. To do.

  In S <b> 17, the CPU determines whether or not the calculated area value S is greater than or equal to a positive seating determination value determined for determining the presence or absence of seating. If the determination in S17 is NO, that is, if no significant convex behavior is detected in the monitoring voltage, the valve body of the fuel injector is not seated normally during the estimated seating period, and therefore It is determined that the fuel injection valve is in an abnormal state (S18), and this process ends.

  If the determination in S17 is YES, that is, if a significant convex behavior to the extent that the area value S exceeds the seating determination value is detected in the monitoring voltage, the CPU detects the valve body during the estimated seating period. Is normally seated, the fuel injection valve is determined to be in a normal state (S19), and the process proceeds to S20. In S20, the CPU specifies the time when the value is the largest among the plurality of difference values Δ (i) calculated in S15, sets this as the seating time t_off, and ends this process (see FIG. 9).

Although one embodiment of the present invention has been described above, the present invention is not limited to this.
For example, in the above-described embodiment, in the re-excitation control in S8, the drive current of the solenoid is increased from the hold current by increasing the duty ratio of the Hi-side switching element 611 from that during the hold control (see FIG. 7). The present invention is not limited to this. For example, as shown in FIG. 10, in the re-excitation control, the Hi-side switching element 611 is turned off and the Hi-side switching element 612 is turned on, and the power source connected to the solenoid is switched from the battery to the booster circuit to drive the solenoid. The current may be made higher than the hold current.

  Moreover, although the said embodiment demonstrated the case where the approximate line which passes the vicinity of a some sampling value was used as the interpolation line (refer FIG. 8), this invention is not limited to this. The interpolation line is not limited to a straight line but may be a curved line.

4 ... Fuel injection valve 41a ... Valve body 43 ... Spring 45 ... Electromagnetic actuator 6 ... ECU (control device)
61 ... Solenoid drive circuit (drive current control means)
611... Hi-side switching element (switching element)
62 ... Booster circuit (second power supply)
65 ... CPU (drive current control means, seating determination means)

Claims (3)

A control device for a fuel injection valve comprising an electromagnetic actuator that generates an electromagnetic force when energized and biases the valve body toward the valve opening side, and a spring that biases the valve body toward the valve closing side,
Drive current control means for controlling the drive current of the electromagnetic actuator to 0 or more during a predetermined valve opening command period;
Seating determination means for determining whether or not the valve body is seated based on a waveform of a counter electromotive voltage generated after stopping energization of the electromagnetic actuator by the drive current control means,
The fuel injection valve, wherein the drive current control means raises the drive current from a hold current determined so as to maintain an open state of the valve body immediately before the valve opening command period ends. Control device. Power supply,
A switching element for intermittently connecting the power source and the electromagnetic actuator,
2. The fuel injection valve control device according to claim 1, wherein the drive current control unit increases the drive current from the hold current by increasing an on / off ratio of the switching element. 3. A first power source, and a second power source having a voltage higher than that of the first power source,
2. The fuel according to claim 1, wherein the drive current control unit raises the drive current from the hold current by switching a power source connected to the electromagnetic actuator from the first power source to the second power source. Control device for injection valve.

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