JP2021134726A - Electronic control device - Google Patents

Abstract

To provide an electronic control device which can extremely improve the detection accuracy of an inflection point, and can extremely exactly detect valve-closing timing.SOLUTION: MOS transistors 9, 10 are arranged in order to turn on/off the electricity-carrying of a power supply to a coil 3 from an upper-side power supply line. A MOS transistor 21 is connected between a downstream-side terminal 1b and the ground. A recirculation MOS transistor 14 is connected between an upstream-side terminal 1a and the ground, and synchronously rectifies a voltage generated at the upstream-side terminal 1a based on an induction electromotive voltage generated at the coil 3 when being complementarily turned on when the MOS transistors 9, 10 are turned off. When the accumulated power of the coil 3 is regenerated to the power supply when the MOS transistors 9, 10 and 21 are turned off, a control IC 6 determines whether or not the regeneration is finished, and on/off-controls the MOS transistor 14 in a state that the MOS transistors 9, 10 are turned off on condition that the finish is determined.SELECTED DRAWING: Figure 1

Description

The present invention relates to an electronic control device that controls valve opening / closing of an injector.

The electronic control device for fuel injection controls the injection of fuel by opening and closing the injector. This electronic control device opens the injector by energizing a driving electromagnetic coil connected between the upstream terminal and the downstream terminal. Further, the electronic control device cuts off the current energized in the electromagnetic coil for driving the injector when the injector is closed.

When the current is cut off, a flyback voltage is generated at the energizing node of the electromagnetic coil. If a flyback voltage is generated when the injector is closed, a voltage float occurs in the downstream terminal voltage of the injector.

In order to recirculate the current corresponding to the flyback voltage, a recirculation circuit using a diode is generally provided. If the freewheeling circuit is composed of a diode, the loss based on the forward voltage of the diode becomes large. In order to reduce this loss, a synchronous rectification method may be adopted by configuring a return switch using a transistor instead of the diode without adopting the diode rectification method.

Conventionally, electronic control devices have attempted to detect the valve closing timing of an injector by detecting an inflection point generated in the waveform of an electromotive force generated in an electromagnetic coil for driving an injector. However, it becomes difficult to detect the inflection point due to the influence of the superimposed voltage superimposed on the downstream terminal of the injector described above, and as a result, it is difficult to improve the detection accuracy of the valve closing timing.

In order to solve this problem, the applicant has proposed the technique described in Patent Document 1. According to the technique described in Patent Document 1, in the recirculation period after the flyback voltage is generated, the cylinder selection switch is turned on / off at least once with the discharge switch turned off on condition that the recirculation end is determined. doing. Then, the residual voltage accumulated in the electromagnetic coil, the capacitor, or the like can be rapidly discharged. After that, the mover moves to a position where the injection port of the injector is fully closed, so that an induced electromotive force is generated in the electromagnetic coil. As a result, the voltage at the downstream terminal rises again, making it easier to detect the inflection point, and the valve closing timing can be detected based on the inflection point.

However, in the technique described in Patent Document 1, it is necessary to control the cylinder selection switch on / off in the vicinity of the valve closing timing. For example, in order to carry out the diagnostic function, when a DC bias voltage is applied, the voltage at the downstream terminal is likely to rise again. Therefore, this re-rising voltage is superimposed on the voltage change caused by the electromotive force of the electromagnetic coil, and there is a possibility that the detection accuracy of the inflection point deteriorates.

Japanese Unexamined Patent Publication No. 2018-127996

An object of the present invention is to provide an electronic control device capable of improving the detection accuracy of an inflection point as much as possible and detecting the valve closing timing as accurately as possible.

The invention according to claim 1 applies an inductive load (3) connected between an upstream terminal (1a) and a downstream terminal (1b) based on a power supply applied between the upper power supply line and the lower power supply line. The target is an electronic control device (1) that opens and closes the injector (2) by driving it. The upstream switches (9, 10) turn on / off the power supply from the upper power supply line to the inductive load. The downstream switch (21) is connected between the downstream terminal and the lower power line.

The return switch (14) is connected between the upstream terminal and the lower power line and occurs at the upstream terminal based on the induced electromotive voltage generated in the inductive load when the upstream switch is turned on complementarily when the upstream switch is turned off. Synchronously rectify the voltage. The on / off control unit (6a) determines whether or not the regeneration has ended when the stored power of the inductive load is regenerated to the power source when the upstream switch and the downstream switch are turned off, and on condition that the termination determination is made. Controls the return switch on and off with the upstream switch turned off.

By controlling the recirculation switch on and off with the upstream switch turned off, the on / off control unit can recirculate the current based on the induced electromotive voltage generated in the inductive load through the recirculation switch, so that the injector valve closing timing The inflection point that occurs in can be made more prominent, the detection accuracy of the inflection point can be improved as much as possible, and the valve closing timing can be detected more accurately.

Electrical configuration diagram of the electronic control device in one embodiment Schematic diagram showing the internal structure of the injector Timing chart Explanatory drawing of the reflux current path when the reflux switch is turned on Explanatory drawing of valve closing detection principle Explanatory drawing of the reflux current path when the reflux switch is turned off Explanation of the principle of improving detectability Flowchart explaining the flow of processing operation Explanatory drawing schematically showing the voltage change during the regeneration period after flyback

Hereinafter, some embodiments of the electronic control device will be described with reference to the drawings. FIG. 1 schematically shows an example of an electrical configuration of an electronic control unit 101 (ECU: Electronic Control Unit). As shown in FIG. 1, the electronic control device 101 is a device that drives, for example, a solenoid type injector 2 (also referred to as an injection valve) that injects and supplies fuel to an internal combustion engine A mounted on a vehicle such as an automobile. be. The injector 2 is a normally closed solenoid valve, and the injector 2 is supplied with pressurized fuel pressurized by a fuel pump (not shown) and is controlled by an electronic control device 101 to open and close the valve. Be spoken. When the injector 2 opens, the pressurized fuel is supplied to the internal combustion engine A.

As shown in FIG. 2, the injector 2 includes a stator 3y including a fixed core constituting an electromagnet, a mover 3z including a needle for opening and closing a fuel injection port, and an electromagnetic coil 3 (hereinafter, coil 3) for exciting the stator 3y. (Abbreviated as: equivalent to inductive load). The coil 3 is designed to have a value on the order of mH (about several Ω).

When the fuel is not injected, the coil 3 is not energized with an electric current. At this time, the mover 3z is urged in the direction of the fuel injection port by an elastic means (for example, a spring) (not shown). Therefore, if the coil 3 is not excited, even if the pressurized fuel is supplied to the injector 2, the fuel is not injected into the internal combustion engine A. When the exciting current is supplied to the coil 3, the mover 3z is attracted toward the stator 3y. Then, the fuel injection port is opened, and the pressurized fuel is injected into the internal combustion engine A.

As shown in FIG. 1, the electronic control device 101 includes a microcomputer 5 (hereinafter, abbreviated as microcomputer 5) that outputs an injection command signal, a control IC 6, an upstream circuit 7, and a downstream circuit 8. The power supply voltage VB is supplied to the upstream circuit 7 from the power supply voltage line that is the upper power supply line. The booster circuit (not shown) is composed of a DCDC converter, and when the battery voltage is input as the power supply voltage VB, the booster voltage V boost that boosts the power supply voltage VB is supplied and output from the boost power supply line that is the upper power supply line to the upstream circuit 7.

The microcomputer 5 is configured to include a CPU 5a, a memory 5b such as a ROM and a RAM, and performs various processing operations based on a program stored in the ROM. The microcomputer 5 calculates the injection command timing based on a sensor signal from a sensor (not shown) provided outside, and outputs the fuel injection command signal to the control IC 6 at this injection command timing.

The control IC 6 is, for example, an integrated circuit device using an ASIC, and includes, for example, a control entity such as a logic circuit or a CPU and a storage unit such as a RAM, ROM, or EEPROM, so as to execute various controls based on hardware and software. It is composed. The control IC 6 functions as an end determination unit and an on / off control unit.

The upstream circuit 7 acts on the coil 3, a MOS transistor 9 for energizing the boost voltage Vboost on / off, an n-channel type MOS transistor 10 for constant current control using the power supply voltage VB, and backflow prevention. The n-channel type MOS transistor 11, the resistor 12, the capacitor 13, the n-channel type MOS transistor 14, the resistors 15 to 18 for adjusting the on / off speed, and the bootstrap capacitors 19 and 20 are connected in the illustrated form. The bootstrap capacitors 19 and 20 form a bootstrap circuit and are used to drive the MOS transistors 9 and 10 on and off at high speed, respectively.

The MOS transistor 9 is configured as a discharge switch (corresponding to an upstream switch). The MOS transistor 10 is configured as a constant current control switch (corresponding to an upstream switch). The MOS transistor 14 is provided for reflux. The MOS transistors 9, 10 and 14 may be configured by using other types of transistors (for example, bipolar transistors).

A boost voltage Vboost is supplied to the drain of the MOS transistor 9, and the source is connected to the upstream terminal 1a. Further, a control signal is input from the control IC 6 to the gate of the MOS transistor 9 through the resistor 15. As a result, the MOS transistor 9 can energize the upstream terminal 1a with the boost voltage Vboost according to the on / off control of the control IC 6.

A power supply voltage VB is supplied to the drain of the MOS transistor 10. The source of the MOS transistor 10 is connected to the upstream terminal 1a via the source and drain of the MOS transistor 11. A control signal is given to the gate of the MOS transistor 10 from the control IC 6 through the resistor 16. As a result, the MOS transistor 10 can energize the upstream terminal 1a with the power supply voltage VB according to the on / off control of the control IC 6.

The MOS transistor 11 with the body diode is connected so that the current based on the boost voltage Vboost is prevented from flowing back to the output node of the power supply voltage VB. Between the upstream terminal 1a and the ground serving as the lower power supply line, the drain source of the MOS transistor 14 for reflux is connected. The MOS transistor 14 is connected to a path for synchronously rectifying the electric power stored in the coil 3 for driving the injector 2. Further, a resistor 12 and a capacitor 13 are connected in parallel between the upstream terminal 1a and the ground serving as the lower power supply line.

The capacitance value of the capacitor 13 is set to, for example, about 1000 pF to 2200 pF, and is provided for emission noise countermeasures or static electricity protection. The resistor 12 is set to, for example, about several tens of kΩ. The resistor 12 is provided to stabilize the potential of the upstream terminal 1a after reflux.

On the other hand, the downstream circuit 8 is configured by connecting an n-channel type MOS transistor 21, a capacitor 22, a diode 23, a current detection resistor 24, and a resistor 25 for selecting energization to the injector 2 in the illustrated form. The MOS transistor 21 is configured as a cylinder selection switch (corresponding to a downstream switch). The MOS transistor 21 may also be configured by using another type of transistor (for example, a bipolar transistor). The capacitance value of the capacitor 22 is set to, for example, about 1000 pF to 2200 pF, and is provided for emission noise countermeasures or static electricity protection.

The drain of the MOS transistor 21 is connected to the downstream terminal 1b. The source of the MOS transistor 21 is connected to the ground which is the lower power supply line through the current detection resistor 24. The gate of the MOS transistor 21 is connected to the control IC 6 through the resistor 25. As a result, the MOS transistor 21 can control the energization / cutoff of the current flowing through the coil 3 according to the on / off control of the control IC 6.

A capacitor 22 is connected between the downstream terminal 1b and the ground serving as the lower power supply line. Further, a regenerative diode 23 is connected in the forward direction between the downstream terminal 1b and the output node of the boosted voltage Vboost. The diode 23 is connected to the energization path of the regenerative current flowing through the coil 3 when the injector 2 is closed.

The control IC 6 includes a control logic 6a that controls MOS transistors 9 to 11, 14, and 21 on or off based on the current detected by the current detection unit 6e and the monitor voltage of the voltage monitor 6d of the downstream terminal 1b. The control IC 6 detects the current applied to the coil 3 of the injector 2 by detecting the voltage between the terminals of the current detection resistor 24 by the current detection unit 6e, and further detects the voltage Vlo of the downstream terminal 1b by the voltage monitor 6d. Therefore, various controls are executed according to these detection signals.

Further, the control IC 6 includes a valve closing detection logic 6b that detects the valve closing timing t7 of the injector 2 based on the voltage Vlo detected by the voltage monitor 6d of the downstream terminal 1b. Further, the control IC 6 includes a voltage monitor 6c of the upstream terminal 1a, and executes various controls based on the voltage Vhi detected by the voltage monitor 6c.

The characteristic control contents according to the present embodiment will be described with respect to the above-mentioned basic configuration.
First, when the electronic control device 101 executes the diagnostic function, the control IC 6 applies a DC bias of about 2.5 V to the upstream terminal 1a by a diagnostic voltage application unit (not shown). Then, the electric charge is accumulated in the capacitor 13, and the coil 3 is energized and the electric charge is also accumulated in the capacitor 22. If the capacitor 13 or 22 is short-circuited for some reason, the detection voltage of the voltage monitor 6c or 6d drops. Therefore, the control IC 6 can detect a failure of the capacitor 13 or 22.

As shown in the timing t1 of FIG. 3, when the microcomputer 5 outputs the injection command signal “H” of the injector 2 to the control IC 6, the control IC 6 controls the MOS transistor 21 on and controls the MOS transistor 21 on. As a result, the current can be supplied to the coil 3 and the injector 2 can be started to open.

At this time, since the boost voltage Vboost is applied to the coil 3 of the injector 2, the drive current of the injector 2 rises sharply, and the electromagnet of the stator 3y of the injector 2 can be quickly magnetized. As a result, the needle inside the injector 2 is attracted by the electromagnet, and the injection port of the injector 2 is finally fully opened.

The control IC 6 measures the current value flowing through the coil 3 by detecting the terminal voltage of the current detection resistor 24 by the current detection unit 6e. The control IC 6 turns off the MOS transistor 9 when the energization current of the coil 3 (hereinafter referred to as an injector current) reaches a predetermined peak current threshold value Ip at the timing t2 of FIG.

The control IC 6 controls the MOS transistors 10 and 11 on and off so that the injector current becomes a predetermined pickup current Ipi at the timings t3 to t4 of FIG. At the same time, the control IC 6 controls the return MOS transistor 14 on / off. At this time, the control IC 6 complementarily controls the MOS transistors 10 and 11 and the MOS transistor 14 on and off.

When the MOS transistors 10 and 11 are turned on, the power supply voltage VB is applied to the capacitors 13, 22 and the coil 3 through the MOS transistors 10 and 11 and the upstream terminal 1a. Then, the voltage Vhi of the upstream terminal 1a rises.

After that, the MOS transistor 14 is turned on at the timing when the MOS transistors 10 and 11 are turned off, and synchronous rectification is performed. As shown in FIG. 4, the recirculation current of the MOS transistor 14 flows toward the ground by recirculating the charging power of the capacitors 13, 22 and the coil 3. Then, the voltage Vhi of the upstream terminal 1a drops. The injector current can be held at a certain pickup current Ipi by repeating the on / off of the MOS transistors 10 and 11 and the MOS transistor 14 in a complementary manner.

Next, the control IC 6 reduces the injector current by turning off the MOS transistors 10, 11 and 14 for a certain period of time. Then, the control IC 6 controls the MOS transistors 10 and 11 on and off so that the injector current becomes a predetermined constant current Iho at the timings t4 to t5 of FIG. When both the MOS transistors 10 and 11 are turned on, the power supply voltage VB is energized to the capacitors 13, 22 and the coil 3 through the MOS transistors 10 and 11 and the upstream terminal 1a. Then, the voltage Vhi of the upstream terminal 1a rises.

After that, the control IC 6 turns off the MOS transistors 10 and 11 and turns on the MOS transistor 14. As shown in FIG. 4, when the charging power of the capacitors 13, 22 and the coil 3 is recirculated in the MOS transistor 14, the recirculation current flows toward the ground. Then, the voltage Vhi of the upstream terminal 1a drops. By turning the MOS transistors 10 and 11 and the MOS transistors 14 on and off in a complementary manner, the injector current can be held at a certain constant current Iho.

The MOS transistors 10 and 11 and the MOS transistor 14 are turned on and off in a complementary manner. As a result, the control IC 6 can hold the injector current so as to have a certain constant current Iho. After that, at the timing t5 of FIG. 3, when the microcomputer 5 outputs the injection command signal of the injector 2 to the control IC 6 as the non-active level “L”, the control IC 6 turns off the MOS transistors 9, 10, 14 and 21. ..

Then, the energizing current to the injector 2 drops rapidly, and the magnetization of the electromagnet of the stator 3y of the injector 2 can be stopped. As a result, the needle inside the injector 2 attracted by the electromagnet is returned to its original position by the urging force of the elastic means (for example, a spring) in response to the extinction of the electromagnetic force, and as a result, the injector 2 closes. ..

At the timing t5 shown in FIG. 3, the control IC 6 changes the MOS transistors 9 to 11, 14, and 21 from the on state to the off state, so that the current flowing through the coil 3 of the injector 2 is rapidly cut off. At this time, the electric power stored in the coil 3 is given to the output node of the boosted voltage Vboost through the diode 23 for reflux.

At this time, when the voltage Vlo of the downstream terminal 1b reaches a voltage Vh (about 65V: to be exact, Vh = Vboost + Vf) close to the boosted voltage Vboost, the voltage Vlo of the downstream terminal 1b is saturated at this voltage Vh and the regenerative current is increased. It flows through the diode 23. As a result, the electric power stored in the coil 3 of the injector 2 can be regenerated, and the electric power stored in the coil 3 of the injector 2 is gradually discharged. Then, when the current stops flowing through the diode 23, the regeneration ends.

Immediately after the end of regeneration, the forward voltage of the diode 23 drops, and the voltage Vlo of the downstream terminal 1b becomes about 65V. Therefore, immediately after the end of regeneration, the electric charge based on the voltage Vlo of the downstream terminal 1b is redistributed between the capacitor 13 of the upstream circuit 7 and the capacitor 22 of the downstream circuit 8. Further, the voltage Vlo decreases based on a time constant determined according to the capacitors 13 and 22, the coil 3 and the resistor 12. The voltage Vlo that changes after the end of regeneration is hereinafter referred to as the residual voltage after regeneration.

On the other hand, when the energization of the coil 3 is stopped, the needle of the mover 3z attracted by the electromagnetic force of the coil 3 moves to the closed position according to the urging force by the elastic means (not shown), thereby moving to the closed position. The injector 2 closes. In particular, as shown in FIG. 5, at the valve closing timing t7 of the injector 2, the mover 3z quickly lifts and moves to change the magnetic flux, and an induced electromotive force is generated in the coil 3. In particular, since the change in magnetic flux is maximized when the valve closing speed is maximum, the interlinkage magnetic flux itself of the coil 3 gradually decreases, but the electromotive force of the coil 3 increases significantly. As a result, the voltage Vlo of the downstream terminal 1b rises.

When the accurate valve closing timing t7 of the injector 2 overlaps with the period in which the residual voltage after regeneration of the downstream terminal 1b gradually decreases, a gradual voltage change according to the time constant of the residual voltage after regeneration is induced in the coil 3. The back electromotive force is superimposed. Then, it becomes difficult to calculate the accurate valve closing timing t7. In particular, as shown in FIG. 6, when the control IC 6 controls the MOS transistor 14 without turning it on, the voltage Vhi of the upstream terminal 1a rises significantly due to the flyback voltage Vf, so that the accurate valve closing timing t7 is calculated. Hateful.

Therefore, in the present embodiment, the control IC 6 temporarily turns off all the MOS transistors 9 to 11, 14, and 21 at the timing t5 of FIG. 3, but after that, and from the timing t6 to t8, the MOS transistor 14 Is turned on again. The above-mentioned residual voltage after regeneration when the MOS transistor 14 is turned off from the timings t6 to t8 in FIG. 3 is schematically shown by a broken line.

When the control IC 6 turns on the MOS transistor 14 at the timings t6 to t8 of FIG. 3, the electric power stored in the coil 3, the capacitors 13, 22 and the like can be quickly discharged to the ground between the timings t6 to t8. Then, the voltage Vhi of the upstream terminal 1a of the coil 3 can be surely set to zero, and the stored power of the capacitor 22 connected to the downstream terminal 1b can be discharged at an early stage. Therefore, the residual voltage after regeneration and the inflection point of the induced electromotive force of the coil 3 around the valve closing timing t7 can be separated.

The control IC 6 can calculate the valve closing timing t7 by acquiring the inflection point of the counter electromotive force induced in the coil 3. The inflection point of the voltage Vlo of the downstream terminal 1b can be calculated by secondarily differentiating the detected voltage of the downstream terminal 1b. In addition, for example, the calculation may be performed using the timing of any one point or two or more points of the rising edge, the maximum value, and the falling edge of the voltage Vlo of the downstream terminal 1b.

FIG. 7 shows an explanatory diagram of the principle of improving detectability. At the valve closing timing t7 of the injector 2, the voltage Vlo of the downstream terminal 1b floats based on the induced electromotive force induced in the coil 3. In the present embodiment, as shown by the broken line in FIG. 7, the stored power of the capacitor 22 of the downstream terminal 1b is discharged by turning on the MOS transistor 14 for reflux.

By discharging the stored power of the capacitor 22 and suppressing the floating of the voltage Vlo of the downstream terminal 1b, the floating of the voltage Vhi of the upstream terminal 1a can also be suppressed. By discharging the stored power of the capacitor 22 at an early stage, it is possible to improve the detection accuracy of the inflection point of the downstream terminal voltage Vl of the injector 2 due to the electromotive force of the coil 3. When the valve closing timing t7 is detected, the influence of the residual voltage after regeneration, which is a fluctuation factor, can be eliminated, and the valve closing timing t7 can be calculated as accurately as possible. As a result, the valve closing detectability can be improved, and the accuracy of minute amount injection can be improved.

In the present embodiment, as compared with the prior art, it is possible to suppress the floating of the voltage Vhi of the upstream terminal 1a while suppressing the floating of the voltage Vlo of the downstream terminal 1b without adding a component or adding a detection logic. Further, by discharging the stored power of the capacitor 22 of the downstream terminal 1b at an early stage, it is possible to improve the detection accuracy of the inflection point of the voltage Vlo of the downstream terminal 1b after flyback.

<Specific example>
Hereinafter, a specific example for realizing such a control content will be described with reference to the flowchart of FIG. 8 and the timing chart of FIG. FIG. 8 shows a specific example of the processing operation when discharging the residual voltage after regeneration, and FIG. 9 shows a main part of the timing chart.

The control IC 6 acquires the voltage Vlo of the downstream terminal 1b in S1 of FIG. 8, and determines in S2 whether or not this voltage Vlo is lower than the flyback voltage Vf. At the timing t5 of FIG. 9, when the microcomputer 5 outputs the injection command signal to the control IC 6 as the non-active level “L”, the control IC 6 turns off all the MOS transistors 10, 11 and 21.

Then, as described above, a counter electromotive force is generated in the coil 3, and the voltage Vlo of the downstream terminal 1b sharply rises to the flyback voltage Vf close to the boost voltage Vboost. In this case, the counter electromotive force is regenerated to the power supply of the boosted voltage Vboost through the diode 23. When the control IC 6 determines that the voltage Vlo is equal to or larger than the flyback voltage Vf, it determines that the current is being regenerated in S2. As the boosted voltage Vboost used for the voltage condition of S2, the control IC 6 detects the voltage of the output node of the boosted voltage Vboost, and the measured value of this detected voltage may be used, or the output standard value of the boosted voltage Vboost may be used. Is also good.

If the control IC 6 determines YES in S2, the control IC 6 calculates the first threshold voltage Vth1 by subtracting a predetermined value from the voltage Vlo detected and acquired in S1. This predetermined value is a predetermined predetermined voltage. In the present embodiment, the first threshold voltage Vth1 is sequentially calculated according to the voltage Vlo of the downstream terminal 1b. Therefore, the first threshold voltage Vth1 is lower than the flyback voltage Vf at the time of reflux.

When the regeneration is completed through the diode 23, the voltage Vlo of the downstream terminal 1b gradually decreases as the residual voltage after the regeneration, as shown in the timings t6 to t8 of FIG. When the residual voltage after regeneration of the downstream terminal 1b satisfies the condition Vlo <Vth1 in S4, the control IC 6 determines that the regeneration is completed, and determines YES in S4. The control IC 6 controls the reflux MOS transistor 14 from off to on in S5 (see timing t6a in FIG. 9). As a result, the residual voltage after regeneration accumulated in the capacitors 13 and 22 can be rapidly discharged.

Then, the control IC 6 acquires the voltage Vlo of the downstream terminal 1b in S6, and determines in S7 whether or not the voltage Vlo is lower than the second threshold voltage Vth2. The second threshold voltage Vth2 is a predetermined voltage lower than the first threshold voltage Vth1. The control IC 6 controls the MOS transistor 21 off again at the timing when the condition Vlo <Vth2 of S7 is satisfied (see S8 in FIG. 8 and timing t8a in FIG. 9).

Since the control IC 6 continuously samples the voltage Vlo of the downstream terminal 1b from the timings t6 to t8a, the timing of the inflection point is calculated by subderivatively differentiating the voltage Vlo in S9 of FIG. The valve closing timing t7 can be calculated based on the above.

<Conceptual summary of the present embodiment>
According to the present embodiment, the control IC 6 controls the MOS transistor 14 as the reflux switch on / off with the MOS transistors 9 to 11 as the upstream switch turned off, provided that the regeneration end is determined. .. Therefore, the stored power of the capacitor 22 can be rapidly discharged through the MOS transistor 14 for reflux. The floating of the voltage Vlo of the downstream terminal 1b and the voltage Vhi of the upstream terminal 1a based on the electromotive force generated in the coil 3 and the stored power of the capacitor 22 can be separated. As a result, the valve closing timing t7 can be detected as accurately as possible.

When the control IC 6 regenerates the flyback voltage Vf to the boosted voltage Vboost side through the diode 23, when it falls below the first threshold voltage Vth1 defined to be lower than the flyback voltage Vf (≈Vboost) during the regeneration period. The MOS transistor 14 is on-controlled and the MOS transistor 14 is off-controlled when the voltage falls below the second threshold voltage Vth2.
In particular, the control IC 6 detects the voltage Vlo during the regeneration period, sets the voltage set to be lower than the voltage Vlo detected during the regeneration period and lower by a predetermined value as the first threshold voltage Vth1, and falls below the first threshold voltage Vth1. At that time, the MOS transistor 14 is on-controlled. The valve closing timing t7 can be detected as accurately as possible by using the simple configuration as described above.

During the period from timing t6 to t8, the control IC 6 turns on the MOS transistor 14 for reflux from off to on, so that the voltage Vh of the upstream terminal 1a can be surely set to zero regardless of the presence or absence of the diagnostic function. According to such an embodiment, improvement in fuel efficiency of the engine system and reduction in emissions can be expected.

(Other embodiments)
The present invention is not limited to the above-described embodiment, and can be implemented in various modifications, and can be applied to various embodiments without departing from the gist thereof. For example, the following modifications or extensions are possible. A plurality of the above-described embodiments may be combined and configured as necessary.

The control IC 6 shows an example in which the period of the timings t6a to t8a of the above-mentioned specific example corresponding to the timings t6 to t8 is obtained by the first threshold voltage Vth1 and the second threshold voltage Vth2, but is limited to this. is not it. For example, a timer built in the control IC 6 may be used to measure the timing and period corresponding to the timings t6 to t8. That is, the timing at which the voltage Vlo of the downstream terminal 1b starts to decrease from the maximum flyback voltage Vf and the period at which the voltage Vlo ends decrease are calculated in advance by circuit simulation, and the timing and period are measured by a timer. You may.

In the above-described embodiment, the voltage Vlo during the regeneration period is detected, and the voltage set to be lower than this voltage Vlo by a predetermined value is sequentially calculated as the first threshold voltage Vth1, but the present invention is not limited to this. The voltage Vth1 may be a fixed voltage. The circuit configuration is not limited to the configuration shown in the above-described embodiment.

A circuit configuration is shown in which the voltage Vlo generated at the downstream terminal 1b is regenerated to the output node of the boosted voltage Vboost, but the circuit is not limited to this, and a capacitor (not shown) is used at the output node of the power supply voltage VB. ) Is provided, the circuit may be configured so as to regenerate this capacitor.

Various control devices may be used instead of the microcomputer 5 and the control IC 6. The means and / or functions provided by this control device can be provided by the software recorded in the substantive memory device and the computer, software, hardware, or a combination thereof that executes the software. For example, when the control device is provided by an electronic circuit which is hardware, it can be configured by a digital circuit including one or more logic circuits or an analog circuit. Further, for example, when the control device executes various controls by software, a program is stored in the storage unit, and the control subject executes the program to implement a method corresponding to the program.

In the above-described embodiment, the coil 3 of the injector 2 for one cylinder is described for simplification of the description, but the same applies to the case of other cylinders such as two cylinders, four cylinders, and six cylinders. Can carry out the contents of. As the MOS transistors 9 to 11, 14, and 21, other types of transistors such as bipolar transistors and various switches may be used.

It may be configured by combining a plurality of the above-described embodiments. In addition, the reference numerals in parentheses described in the claims indicate the correspondence with the specific means described in the above-described embodiment as one aspect of the present invention, and the technical scope of the present invention is defined. It is not limited. An embodiment in which a part of the above-described embodiment is omitted as long as the problem can be solved can also be regarded as an embodiment. In addition, any conceivable aspect can be regarded as an embodiment as long as it does not deviate from the essence of the invention specified by the wording described in the claims.

Although the present invention has been described in accordance with the above-described embodiment, it is understood that the present invention is not limited to the embodiment or structure. The present disclosure also includes various modifications and modifications within a uniform range. In addition, various combinations and forms, as well as other combinations and forms including one element, more, or less, are also within the scope and ideology of the present invention.

In the drawing, 101 is an electronic control device, 2 is an injector (injection valve), 3 is a coil (inductive load), 6 is a control IC (on / off control unit), 9 is a MOS transistor (upstream switch), and 10 is a MOS transistor ( Upstream switch), 21 indicates a MOS transistor (downstream switch).

Claims (2)

The injector (2) is driven by driving an inductive load (3) connected between the upstream terminal (1a) and the downstream terminal (1b) based on the power supplied between the upper power line and the lower power line. An electronic control device (101) that opens and closes the valve.
Upstream switches (9, 10) for energizing the power supply from the upper power supply line to the inductive load, and
A downstream switch (21) connected between the downstream terminal and the lower power line,
Synchronized with the voltage generated at the upstream terminal based on the induced electromotive voltage generated at the inductive load when connected between the upstream terminal and the lower power line and complementarily turned on when the upstream switch is turned off. Reflux switch (14) for rectification and
When the upstream switch and the downstream switch are turned off, if the stored power of the inductive load is regenerated to the power source, it is determined whether or not the regeneration is completed, and the upstream switch is turned off on condition that the end determination is made. The on / off control unit (6) that controls the on / off of the reflux switch in the state of being
An electronic control device comprising. The electronic control device according to claim 1, wherein the on / off control unit controls the reflux switch on / off based on a voltage applied to the downstream terminal.

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