JP6878936B2 - Electronic control device - Google Patents

Description

The present invention relates to an electronic control device that controls the opening and closing of an injection valve.

This type of electronic control device is used to open and close the injection valve and inject fuel. Conventionally, when detecting the valve closing timing of the injection valve, the electromotive force when the needle formed inside the injection valve closes is measured, and the valve closing timing is detected based on the measurement result (for example). , Patent Document 1).

When the electronic control device closes and controls the injection valve, the electronic control device cuts off the current energized in the electromagnetic coil for driving the injection valve. When the current is cut off, a flyback voltage is generated at the energizing node of the electromagnetic coil. Therefore, in order to effectively utilize the electric power corresponding to the flyback, a reflux circuit may be provided to return the current generated according to the flyback voltage to the power supply circuit. If this type of recirculation circuit is provided, the residual voltage period that occurs after the recirculation period that returns the flyback voltage to the power supply circuit and the valve closing timing of the injection valve generally overlap, and the valve closing timing is detected. It becomes difficult to do.

Therefore, according to the technique described in Patent Document 1, the electromotive force superimposed on the residual voltage generated after recirculation by the recirculation circuit is filtered by two types of filters in which different cutoff frequencies are set, respectively, and after this filter processing. The voltage difference is compared, and the valve closing timing is detected based on the time when the voltage difference after this filter becomes a turning point.

JP-A-2015-96720

When the technique described in Patent Document 1 is used, when the tolerance of the elements constituting the circuit is large or when the temperature change is expected to be large, this influence affects the change of the time constant. The degree of decrease in residual voltage changes. Therefore, there is a possibility that the valve closing timing cannot be detected with high accuracy. Moreover, according to the technique described in Patent Document 1, complicated arithmetic processing using two types of filters is required to extract the electromotive force.

An object of the present invention is to provide an electronic control device capable of accurately detecting a valve closing timing by using a simple configuration.

The invention according to claim 1 is an upstream switch for turning on / off an inductive load for opening / closing an injection valve for supplying fuel to an internal combustion engine, and a downstream switch for selecting an injection valve. A recirculation circuit that recirculates the signal generated on the downstream switch side to the power supply, an end determination unit that determines the end of recirculation by the recirculation circuit according to the detected voltage that detects the voltage generated on the downstream switch side, and an end determination unit. It includes an on / off control unit that controls the downstream switch on / off at least once with the upstream switch turned off on condition that the end is determined.

According to the first aspect of the present invention, on the condition that the end of reflux is determined by the end determination unit, the downstream switch is turned on / off at least once with the upstream switch turned off, so that the downstream switch side It is possible to stabilize the voltage generated in the inductive load, and it becomes easy to detect the voltage change due to the electromotive force generated in the inductive load when the injection valve is closed. As a result, the valve closing timing can be accurately detected using a simple configuration.

Electrical configuration diagram of the electronic control device according to the first embodiment Structural drawing schematically showing the injection valve in the first embodiment Timing chart that roughly shows the signal change of each part in the first embodiment Flowchart schematically showing the processing operation in the first embodiment Enlarged view of the main part of the timing chart of FIG. 3 in the first embodiment Flowchart schematically showing the processing operation in the second embodiment Timing chart that roughly shows the signal change of each part in the second embodiment

Hereinafter, some embodiments of the electronic control device will be described with reference to the drawings. In each of the embodiments described below, configurations that perform the same or similar operations are designated by the same or similar reference numerals, and the description thereof will be omitted as necessary.

(First Embodiment)
1 to 5 are explanatory views of the first embodiment. FIG. 1 schematically shows an example of an electrical configuration of an electronic control unit (ECU) 101. As shown in FIG. 1, the electronic control device 101 has N, for example, solenoid-type injection valves (also referred to as injectors) that inject and supply fuel to an N-cylinder internal combustion engine A mounted on a vehicle such as an automobile. It is a device that drives 2a and 2b. Here, an example of N = 2 cylinders is shown. The injection valves 2a and 2b are normally closed solenoid valves, and the injection valves 2a and 2b are supplied with pressurized fuel pressurized by a fuel pump (not shown) and controlled by the electronic control device 101. The valve is opened and closed at. When the injection valves 2a and 2b are opened, pressurized fuel is supplied to the internal combustion engine A.

As shown in FIG. 2, the injection valves 2a and 2b are an electromagnetic coil that excites 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 a stator 3y (hereinafter referred to as an electromagnetic coil). Abbreviated as coil: equivalent to inductive load) 3a and 3b are provided, respectively. The coils 3a and 3b are designed to have values on the order of mH (about several Ω).

When the fuel is not injected, the coils 3a and 3b are not energized with an electric current, and 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 coils 3a and 3b are not excited, even if the pressurized fuel is supplied to the injection valve 2a or 2b, the fuel is not injected into the internal combustion engine A. When the exciting current is supplied to the coil 3a or 3b, 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.

The electronic control device 101 includes a power supply circuit 4, a microcomputer (hereinafter abbreviated as a microcomputer) 5, a control IC 6, an upstream circuit 7, and a downstream circuit 8. The power supply circuit 4 is configured to output two different types of power supplies (for example, power supply voltage VB and boost voltage Vboost) to the upstream circuit 7, for example, the battery voltage is electronically controlled by operating an ignition switch (not shown). When supplied to the device 101, the battery voltage can be output as a power supply voltage VB, and a boosted voltage Vboost boosted by a DCDC converter (not shown) is generated in the output capacitor 4a so that the battery voltage can be output from the output capacitor 4a. To do.

The microcomputer 5 is configured to include a CPU, a ROM, a RAM, an I / O, and the like (none of which are shown), 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. This control IC 6 is used as an end determination unit and an on / off control unit.

The upstream circuit 7 is a discharge switch (corresponding to an upstream switch) 9 for energizing the boost voltage Vboost to the coils 3a and 3b, and a constant current control switch for constant current control using the power supply voltage VB (hereinafter,). It is abbreviated as a constant current switch (corresponding to an upstream switch) 10, diodes 11, 12, resistors 13, and a capacitor 14 are connected as shown in the figure, and are connected to an output terminal 1a on the upstream side.

The discharge switch 9 and the constant current switch 10 are configured by using, for example, an n-channel type MOS transistor. These discharge switches 9 and constant current switches 10 may be configured by using other types of transistors (for example, bipolar transistors), but in the present embodiment, a case where an n-channel type MOS transistor is used will be described. A boost voltage Vboost is supplied from the power supply circuit 4 to the drain of the MOS transistor constituting the discharge switch 9, the source is connected to the output terminal 1a on the upstream side, and a control signal is given to the gate from the control IC 6. As a result, the discharge switch 9 energizes the output terminal 1a with the boost voltage Vboost of the power supply circuit 4 according to the control of the control IC 6.

A power supply voltage VB is supplied from the power supply circuit 4 to the drain of the MOS transistor constituting the constant current switch 10, the source is connected in the forward direction to the output terminal 1a on the upstream side via the diode 11, and the gate is controlled. A control signal is given from the IC6. As a result, the constant current switch 10 energizes the output terminal 1a with the power supply voltage VB according to the control of the control IC 6.

The diode 11 is connected to prevent backflow from the output node of the boost voltage Vboost of the power supply circuit 4 to the output node of the power supply voltage VB. A diode 12 for reflux is connected in the opposite direction between the output terminal 1a on the upstream side and the ground node 15, and a resistor 13 and a capacitor 14 are connected in parallel. The return diode 12 is connected to a current path that returns when the injection valves 2a and 2b are closed.

The downstream circuit 8 shows cylinder selection switches (corresponding to downstream switches) 16 and 17 for selecting injection valves 2a and 2b, capacitors 18 and 19, diodes 20 and 21 as a reflux circuit, and a current detection resistor 22. It is configured by connecting to the form, and is connected to the output terminals 1b and 1c on the downstream side. The current detection resistor 22 is set to, for example, about 0.3Ω.

The cylinder selection switches 16 and 17 are configured by using, for example, an n-channel type MOS transistor. The capacitance values of the capacitors 14 and 18 are set to, for example, about 1000 pF to 2200 pF, and are provided for emission noise countermeasures or static electricity protection. The resistor 13 is set to a value of, for example, about 20 kΩ. The resistor 13 is provided to stabilize the output terminal 1a on the upstream side after reflux to the ground level.

The cylinder selection switches 16 and 17 may also be configured by using other types of transistors (for example, bipolar transistors), but in the present embodiment, a case where a MOS transistor is used will be described.

The drains of the MOS transistors constituting the cylinder selection switches 16 and 17 are connected to the output terminals 1b and 1c on the downstream side, respectively, the source is connected to the ground node 15 through the current detection resistor 22, and the gate is connected to the control IC6. There is. As a result, the cylinder selection switches 16 and 17 can selectively energize the current flowing through the coils 3a and 3b according to the control of the control IC6.

Capacitors 18 and 19 are connected between the output terminals 1b and 1c on the downstream side and the ground node 15, respectively. Further, the return diodes 20 and 21 are connected in the forward direction between the output terminals 1b and 1c on the downstream side and the output node of the boosted voltage Vboost by the power supply circuit 4, respectively.

The diodes 20 and 21 are connected to the energization paths of the recirculation currents flowing through the coils 3a and 3b when the injection valves 2a and 2b are closed, respectively, and the power supply circuit 4 is connected from the downstream cylinder selection switches 16 and 17, respectively. It is a recirculation circuit that recirculates a current toward the output capacitor 4a of the above, and is connected so as to charge the recirculation current to the output capacitor 4a of the power supply circuit 4 when the injection valves 2a and 2b are closed.

The control IC 6 controls the switches 9, 10, 16 and 17 described above to be turned on or off. Then, the control IC 6 detects the current applied to the coils 3a and 3b of the injection valves 2a and 2b by detecting the voltage between the terminals of the current detection resistor 22, and executes various controls according to the detection signal.

The operation of the above configuration will be described. When the battery voltage is supplied to the electronic control device 101, the power supply circuit 4 generates the power supply voltage VB and also generates and outputs the boosted voltage Vboost. Although not shown for simplification in FIG. 1, the power output of the power supply circuit 4 is given to the microcomputer 5 and the control IC 6, whereby the microcomputer 5 and the control IC 6 are activated. ..

As shown in the timing t1 of FIG. 3, when the microcomputer 5 outputs the active level “H” of the injection command signal of the injection valve 2a to the control IC 6, the control IC 6 turns on the cylinder selection switch 16 and also controls the discharge switch 9 and the discharge switch 9. The constant current switch 10 is turned on and controlled, whereby a current is supplied to the coil 3a of the injection valve 2a to start opening the injection valve 2a.

At this time, since the boost voltage Vboost is supplied to the coil 3a of the injection valve 2a, the current for opening the injection valve 2a rises sharply, and the electromagnet of the stator 3y of the injection valve 2a can be quickly magnetized. .. As a result, the needle inside the injection valve 2a is attracted by the electromagnet, and the injection valve 2a is finally fully opened. As shown in FIG. 3 showing the valve opening transition state of the injection valve 2a, a delay time Ta occurs from the timing t1 when the power supply to the coil 3a is started to the timing ta when the injection valve 2a is completely opened.

The control IC 6 measures the current value by detecting the terminal voltage of the current detection resistor 22. The control IC 6 turns off the discharge switch 9 and the constant current switch 10 when the energization current of the coil 3a (hereinafter referred to as an injector current) reaches a predetermined peak current threshold value Ip at the timing t2 of FIG. After that, the control IC 6 controls the constant current switch 10 on / off so that the injector current falls within a predetermined constant current range at the timings t3 to t4 of FIG. As a result, the control IC 6 can control the injector current so as to have a constant current range within a certain range.

After that, at the timing t5 of FIG. 3, when the microcomputer 5 outputs the injection command signal of the injection valve 2a to the control IC 6 as the non-active level “L”, the control IC 6 has the discharge switch 9, the constant current switch 10, and the cylinder selection switch. 16 is off-controlled. Then, the injector current drops sharply, and the magnetization of the electromagnet of the stator 3y of the injection valve 2a can be stopped. As a result, the needle inside the injection valve 2a 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 injection valve 2a is closed. To do. FIG. 3 shows the valve closing transition state of the injection valve 2a, but the delay time Tb is set between the timing t5 when the power supply to the coil 3a is stopped and the timing t7 when the injection valve 2a is completely closed. Occurs.

Here, at the timing t5 of FIG. 3, in order to change all the switches 9, 10 and 16 from the on state to the off state, the current flowing through the coil 3a of the injection valve 2a is suddenly cut off. At this time, the energy stored in the coil 3a is given to the output node of the boosted voltage Vboost of the power supply circuit 4 through the diode 20 for reflux.

At this time, when the voltage Vlo of the output terminal 1b on the downstream side reaches a voltage Vh (about 65V: to be exact, Vh = Vboost + Vf) close to the boosted voltage Vboost, the voltage Vlo of the output terminal 1b is saturated at this voltage Vh. The return current flows through the diode 20, and the energy stored in the coil 3a of the injection valve 2a can be regenerated into the output capacitor 4a of the power supply circuit 4. As a result, the energy stored in the coil 3a of the injection valve 2a is gradually discharged. Then, when the current stops flowing to the diode 20, the reflux ends.

Immediately after the end of reflux, the terminal voltage of the output terminal 1a on the upstream side is about -1V (= negative value of the forward voltage of the diode 12), and the terminal voltage Vlo of the output terminal 1b on the downstream side is about 65V. Become. Therefore, after the end of reflux, the charge based on the voltage Vlo of the output terminal 1b is redistributed between the capacitor 14 of the upstream circuit 7 and the capacitor 18 of the downstream circuit 8, and further, the voltage Vlo is further distributed. Decreases based on a time constant determined according to the capacitors 14 and 18, the coil 3a, and the resistor 13. The voltage Vlo that changes after the end of reflux is hereinafter referred to as the residual voltage after reflux.

On the other hand, when the energization of the coil 3a is stopped, the needle of the mover 3z attracted by the electromagnetic force of the coil 3a moves to the closed position according to the urging force by the elastic means (not shown), thereby moving to the closed position. The injection valve 2a is closed. In particular, at the valve closing timing t7 of the injection valve 2a shown in FIG. 3, the needle of the mover 3z moves quickly, so that a large mutual induction action is generated in the coil 3a. As a result, an induced electromotive force is generated in the coil 3a, and the voltage Vlo of the output terminal 1b rises. The control IC 6 acquires the inflection point of the counter electromotive force induced in the coil 3a (for example, the timing of any one or two or more points of the rising edge, the maximum value, and the falling edge of the voltage Vlo of the output terminal 1b). The valve closing timing t7 can be calculated accordingly.

When the accurate valve closing timing t7 of the injection valve 2a overlaps with the period in which the residual voltage after reflux gradually decreases as the residual voltage after reflux, a gradual voltage change according to the time constant of the residual voltage after reflux is induced in the coil 3a. Since the counter electromotive force is superimposed, it becomes difficult to calculate the accurate valve closing timing t7.

Therefore, in the present embodiment, the control IC 6 temporarily turns off all the switches 9, 10 and 16 at the timing t5 of FIG. 3, but then turns the cylinder selection switch 16 at the timing t6 after that and before the valve closing timing t7. I am trying to control on / off again. The above-mentioned residual voltage after reflux when the cylinder selection switch 16 is not turned on / off at the timing t6 is schematically shown by a broken line from the timings t6 to t7 in FIG.

By controlling the cylinder selection switch 16 to be turned on / off again at the timing t6, the energy stored in the coil 3a, the capacitors 14, 18 and the like can be quickly discharged to the ground node 15 at the timing t6, and remains after reflux. The voltage and the induced electromotive force induced in the coil 3a at the valve closing timing t7 can be separated as much as possible.

At the valve closing timing t7 of the injection valve 2a, the voltage Vlo of the output terminal 1a rises again based on the induced electromotive force induced in the coil 3a, but the control IC 6 applies the counter electromotive force induced in the coil 3a. It is detected by acquiring the voltage Vlo of the output terminal 1b, and the valve closing timing t7 is calculated by acquiring the turning point of this counter electromotive force. Thereby, the accurate valve closing timing t7 can be calculated and acquired. As a result, the induced electromotive force generated at the valve closing timing t7 of the injection valve 2a can be measured without superimposing it on the residual voltage after refluxing as much as possible, and the influence of the residual voltage after refluxing which becomes a fluctuation factor when the valve closing timing t7 is detected. Can be eliminated, and the valve closing timing t7 can be accurately obtained.

The timings t11 to t17 of FIG. 3 show the energization control method of the coil 3b of the injection valve 2b, but the flow is substantially the same as the energization control method of the coil 3a of the injection valve 2a. Therefore, t11 to t17 are added to the timings related to the injection valve 2b so as to correspond to the timings t1 to t7 related to the injection valve 2a, respectively, and the description thereof will be omitted.

<Specific example>
Hereinafter, a specific example for realizing such a control method will be described with reference to the flowchart of FIG. 4 and the timing chart of FIG. FIG. 4 shows a specific example of the processing operation when discharging the residual voltage after reflux, and FIG. 5 shows an enlarged view of a main part of the timing chart shown in FIG.

First, the control IC 6 acquires the voltage Vlo of the output terminal 1b in S1 of FIG. 4, and determines in S2 whether or not this voltage Vlo is lower than the boosted voltage Vboost. At the timing t5 of FIG. 5, when the microcomputer 5 outputs the injection command signal as the non-active level “L” to the control IC 6, the control IC 6 turns off the discharge switch 9, the constant current switch 10, and the cylinder selection switch 16. ..

Then, as described above, a counter electromotive force is generated in the coil 3a, and the voltage Vlo of the output terminal 1b sharply rises to a voltage Vh (to be exact, Vh = Vboost + Vf) close to the boosted voltage Vboost. In this case, this counter electromotive force is returned to and charged to the output capacitor 4a of the power supply circuit 4 through the diode 20. When the control IC 6 determines that the voltage Vlo is larger than the boosted voltage Vboost, it determines that the current is being recirculated. The voltage condition Vlo> Vboost in S2 does not consider the forward voltage Vf of the diode 20, but the condition may be derived in consideration of the forward voltage Vf. Further, as the boosted voltage Vboost used for the voltage condition of S2, the control IC 6 may detect the voltage of the output node of the boosted voltage Vboost and use the measured value of this detected voltage, or use the output standard value of the boosted voltage Vboost. You may.

When the control IC 6 determines YES in S2, the control IC 6 calculates the first threshold voltage Vth1 by subtracting the predetermined value Vsys1 from the voltage Vlo detected and acquired in S1. This predetermined value Vsys1 is a predetermined predetermined voltage. In the present embodiment, the first threshold voltage Vth1 is sequentially calculated according to the voltage Vlo. Therefore, the first threshold voltage Vth1 is lower than the voltage Vh at the time of reflux.

When the reflux treatment through the diode 20 is completed, as shown in the timings t6a to t6b of FIG. 5, the voltage Vlo gradually decreases as the residual voltage after reflux as described above. When the residual voltage after reflux satisfies the condition Vlo <Vth1 in S5, the control IC 6 determines that the reflux is completed and determines YES in S5. The control IC 6 turns on the cylinder selection switch 16 at the timing t6b of FIG. 5 in S6 of FIG. As a result, the residual voltage accumulated in the coil 3a, the capacitor 18, and the like can be rapidly discharged.

Then, the control IC 6 acquires the value of the voltage Vlo in S7, and determines in S8 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. As shown in the timing t6c of FIG. 5, the control IC 6 controls the cylinder selection switch 16 to be turned off again at the timing when the condition Vlo <Vth2 of S8 is satisfied (S9 of FIG. 4).

Then, the control IC 6 acquires the voltage Vlo in S10 of FIG. 4, and calculates the valve closing timing t7 based on the inflection point of the voltage Vlo at the timings t7a to t7c of FIG. When the current of the coil 3a is cut off, the attraction of the mover 3z according to the energizing current of the coil 3a is released. Then, the mover 3z moves to a position where the injection port of the injection valve 2a is fully closed. At this time, since the mover 3z operates, an induced electromotive force is generated in the coil 3a, and the voltage Vlo rises.

The inflection point of the voltage Vlo at the time of this re-rise is at least one or more timings of the timing t7a rising from the ground level, the timing t7b reaching the maximum value, and the timing t7c falling from the maximum value and reaching the ground level. The control IC 6 calculates the timings t7a to t7c of the inflection point by continuously sampling the voltage Vlo over the timings t6 to t7c, and can calculate the valve closing timing t7 based on the timings t7a to t7c. Since the mover 3z reaches the maximum speed at the timing immediately before the injection port is fully closed, the induced electromotive force becomes maximum at this timing t7b, and the valve closing timing t7 is calculated based on the timing t7b at which this voltage value becomes maximum. good.

<Comparison example>
The inventor understands that the slope of the residual voltage after reflux is affected by changes in the time constant of the circuit due to device tolerances and temperature. This hinders the detection of the valve closing timing t7 with high accuracy.

<Conceptual summary of the present embodiment>
In short, according to the present embodiment, the control IC 6 controls the cylinder selection switch 16 once on / off with the discharge switch 9 and the constant current switch 10 turned off, provided that the end of reflux is determined. There is. Therefore, the residual voltage after reflux can be rapidly discharged through the cylinder selection switch 16, and the discharge period of the residual voltage after reflux can be separated from the valve closing timing t7 as much as possible. Thereby, the valve closing timing t7 can be detected as accurately as possible by using the simple configuration as described above.

When determining the end of reflux by the diode 20, the control IC 6 determines that the reflux is complete on condition that the voltage Vh (≈Vboost) during the reflux period is lower than the first threshold voltage Vth1. There is. In particular, the control IC 6 detects the voltage Vh during the reflux period when determining the end of reflux by the diode 20, and sets a voltage lower than the detection voltage Vh during the reflux period and a predetermined value Vsys1 lower than the first threshold voltage. It is determined that the reflux is completed on the condition that Vth1 is set and the voltage is lower than the first threshold voltage Vth1.

In such a case, the period from the end of reflux to turning on the cylinder selection switch 16 can be shortened as much as possible. Further, if the cylinder selection switch 16 is turned on during the recirculation period, a large current flows through the cylinder selection switch 16, which is not preferable. However, since the cylinder selection switch 16 is turned on after it is determined that the recirculation is completed, the coil. While the stored power of the 3a and the capacitor 18 and the like is regenerated to the output capacitor 4a, the power that cannot be regenerated can be quickly discharged thereafter.

The control IC 6 controls the cylinder selection switch 16 to be turned off when the voltage Vlo falls below the second threshold voltage Vth2 after the cylinder selection switch 16 is turned on. That is, for example, before the timing t7 when the injection valve 2a actually closes, the voltage Vlo can be lowered to a voltage lower than the second threshold voltage Vth2 at least once, and occurs around the valve opening timing t7. The change in voltage Vlo due to the counter electromotive force can be easily separated, and the valve opening timing t7 can be detected as accurately as possible.

(Second Embodiment)
6 and 7 show additional explanatory views of the second embodiment. The same parts as those in the above-described embodiment are designated by the same reference numerals and the description thereof will be omitted, and the processing contents for which the same processing is performed will be described by adding the same step numbers. FIG. 6 is a flowchart showing a specific example of the operation when the residual voltage is discharged after reflux. In this embodiment, a mode in which the control IC 6 measures the elapsed time using the built-in timer and controls the on / off timing of the cylinder selection switch 16 will be described.

As shown in FIG. 6, the control IC 6 performs the processes of steps S1 to S6 in the same manner as those described in the above-described embodiment, so that the cylinder selection switch 16 is pressed when the voltage Vlo falls below the first threshold voltage Vth1. On control. As a result, the residual voltage accumulated in the capacitor 18 or the like can be rapidly discharged.

Then, the control IC 6 determines whether or not the predetermined time T1 has elapsed by the built-in timer in S6a of FIG. 6, and when the predetermined time T1 elapses, turns off the cylinder selection switch 16 in S9 of FIG.

Next, the control IC 6 determines whether or not the second predetermined time T2 predetermined by the built-in timer has elapsed. Here, the predetermined time T2 is set to a time larger than the first predetermined time T1 as shown in FIG. 7, and it is assumed that the induced electromotive force is detected from the timing t6b when the cylinder selection switch 16 is turned on. It is desirable that the time is set to the timing t8 immediately before the timing t7a.

When the second predetermined time T2 elapses, the control IC 6 determines YES in S12, forcibly acquires the voltage Vlo in S10, and then bases it on the inflection point (timing t7a to t7c) of the voltage Vlo in S11. The valve closing timing t7 is calculated (see the timing t8 and later in FIG. 7).

Further, the control IC 6 acquires the voltage Vlo in S7 if the predetermined time T2 has not elapsed in S12, and determines whether or not the voltage Vlo is lower than the threshold voltage Vth3 (for example, 1V) in S13 (FIG. 7). Timing t6e). When the voltage Vlo is equal to or higher than the threshold voltage Vth3, the control IC 6 returns the process to S6 and controls the cylinder selection switch 16 to be turned on / off again (timing t6f, t6g in FIG. 7).

That is, even if the control IC 6 turns on the cylinder selection switch 16 at the timing t6b of FIG. 7 and the predetermined time T1 elapses, the residual power may be accumulated in the coil 3a, the capacitor 14, and the like. Therefore, even when the control IC 6 turns off the cylinder selection switch 16 again at the elapsed timing t6d of the predetermined time T1, the stored energy of the coil 3a is released to the capacitor 18 as shown in the timings t6d to t6f of FIG. Therefore, the voltage Vlo may be equal to or higher than the threshold voltage Vth3. Therefore, the control IC 6 repeatedly turns on and off the cylinder selection switch 16 as shown in S6 to S9 of FIG. 6 until it is determined in S12 of FIG. 6 that the predetermined time T2 has elapsed. ..

Then, almost all the electric power remaining in the coil 3a and the capacitor 18 can be discharged. The number of times of on / off control of the cylinder selection switch 16 by the processing of S6 to S9 may be controlled at least once, but it is desirable that the number of times is set to two or three times or more. More preferably, it should be twice or less. In particular, almost all residual power can be discharged by repeating on / off twice. As a result, almost all the residual power can be discharged until the predetermined time T2 elapses, and the voltage change according to the induced electromotive force of the coil 3a accompanying the movement of the mover 3z can be detected as accurately as possible. The valve closing timing t7 can be calculated as accurately as possible. As a result, the injection amount can be accurately detected, and the valve closing timing t7 and the injection amount can be utilized for later control.

<Conceptual summary of this embodiment>
Further, since the control IC 6 turns on the cylinder selection switch 16 again when the detection voltage exceeds the third threshold voltage Vth3 after the timing t6d when the cylinder selection switch 16 is turned off, even if the energy is the coil 3a or the capacitor. Even if it remains at 18 mag, this energy can be re-discharged. Therefore, the voltage change according to the induced electromotive force of the coil 3a can be detected as accurately as possible, and the valve closing timing t7 can be calculated as accurately as possible.

Further, since the control IC 6 stops the on / off control of the cylinder selection switch 16 at the timing t6g after the lapse of the second predetermined time T2 from the timing t6b for determining the end of reflux, it is before the valve closing timing t7. The cylinder selection switch 16 can be surely turned off, and then the valve closing timing t7 can be easily detected by using the change in the voltage Vlo.

(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.

In the first embodiment, the voltage Vlo during the reflux period is detected, and the voltage set to be lower than the detected voltage Vlo by a predetermined value Vsys1 is sequentially calculated as the first threshold voltage Vth1, but the present invention is not limited to this. The first threshold voltage Vth1 may be a fixed voltage.

As the "signal and voltage generated on the downstream switch side", the form in which the signal and voltage of the output terminals 1b and 1c connected to the cylinder selection switches 16 and 17 are applied is shown, but the present invention is not limited to this. For example, the signal and voltage of the common connection point with the current detection resistor 22 may be applied, or the signal and voltage of another node in the downstream circuit 8 may be applied. Further, the circuit configuration is not limited to the configuration shown in the above-described embodiment.

The form in which the voltage generated in the output terminals 1b and 1b is returned to the output capacitor 4a of the boost voltage Vboost in the power supply circuit 4 is shown, but the present invention is not limited to this, and the output node of the power supply voltage VB of the power supply circuit 4 is shown. When a capacitor (not shown) is provided, the circuit may be configured so as to return to this capacitor. That is, it can also be applied to a configuration in which the current returns to the constant current switch 10.

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 entity executes the program to implement a method corresponding to the program.

In the above-described embodiment, for the sake of simplification of the description, the coils 3a and 3b of the injection valves 2a and 2b for two cylinders have been described, but in the case of other cylinders such as four cylinders and six cylinders, the description has been given. Can also carry out the same content.

In the above-described embodiment, the discharge switch 6, the constant current switch 7, and the cylinder selection switches 16 and 17 have been described using MOS transistors, but other types of transistors such as bipolar transistors and various switches may be used.

A plurality of the above-described embodiments may be combined and configured. 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 disclosure has been described in accordance with the above-described embodiments, it is understood that the present disclosure is not limited to the embodiments and structures. The present disclosure also includes various modifications and modifications within an equal 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 of the present disclosure.

In the drawing, 101 is an electronic control device, 2a and 2b are injection valves, 3a and 3b are electromagnetic coils (induction load), 6 is a control IC (end determination unit, on / off control unit), and 9 is a discharge switch (upstream switch). 10 is a constant current switch (upstream switch), 16 and 17 are cylinder selection switches (downstream switch), and 20 and 21 are diodes (circulation circuit).

Claims (7)

The power supply circuit (4) is configured to supply power (Vboost, VB) to the inductive load (3a, 3b) for opening and closing the injection valves (2a, 2b) that supply fuel to the internal combustion engine. Electronic control device
An upstream switch (9, 10) for turning on / off the inductive load (3a, 3b) and
Downstream switches (16, 17) for selecting the injection valve,
A reflux circuit (20, 21) that returns a signal generated on the downstream switch side to the power supply, and
An end determination unit (6) that determines the end of reflux by the reflux circuit according to the detected voltage that detects the voltage generated on the downstream switch side.
An on / off control unit (6) that controls on / off of the downstream switch at least once with the upstream switch turned off on condition that the end determination is made by the end determination unit is provided.
The on / off control unit is an electronic control device that turns on the downstream switch again when the detected voltage exceeds the third threshold voltage (Vth3) after the timing (t6d) when the downstream switch is turned off. When the end determination unit determines the end of reflux by the reflux circuit, the end of reflux is determined on the condition that the end is lower than the first threshold voltage (Vth1) defined to be lower than the voltage (Vh) during the reflux period. The electronic control device according to claim 1. The power supply circuit (4) is configured to supply power (Vboost, VB) to the inductive load (3a, 3b) for opening and closing the injection valves (2a, 2b) that supply fuel to the internal combustion engine. Electronic control device
An upstream switch (9, 10) for turning on / off the inductive load (3a, 3b) and
Downstream switches (16, 17) for selecting the injection valve,
A reflux circuit (20, 21) that returns a signal generated on the downstream switch side to the power supply, and
An end determination unit (6) that determines the end of reflux by the reflux circuit according to the detected voltage that detects the voltage generated on the downstream switch side.
An on / off control unit (6) that controls on / off of the downstream switch at least once with the upstream switch turned off on condition that the end determination is made by the end determination unit is provided.
The end determination unit detects the voltage (Vh) during the reflux period when determining the end of reflux by the reflux circuit, and sets the voltage lower than the detection voltage during the reflux period by a predetermined value (Vsys1). Is sequentially calculated as the first threshold voltage (Vth1), and the electronic control device determines that the reflux is completed on condition that the voltage falls below the first threshold voltage. The electronic control according to any one of claims 1 to 3, wherein the on / off control unit turns off the downstream switch when the detected voltage falls below the second threshold voltage (Vth2) after the downstream switch is turned on. apparatus. The on / off control unit is any one of claims 1 to 3 in which the downstream switch is turned off at a timing (t6d, t6g) when a first predetermined time (T1) has elapsed from the timing when the downstream switch is turned on (t6b, t6f). The electronic control device according to one item. Any one of claims 3 to 5, wherein the on / off control unit turns on the downstream switch again when the detected voltage exceeds the third threshold voltage (Vth3) after the timing (t6d) when the downstream switch is turned off. The electronic control device according to. At the timing (t6g) after the lapse of the second predetermined time (T2) from the timing (t6b) when the end determination unit determines the end of reflux by the reflux circuit, the on / off control unit controls the on / off of the downstream switch. The electronic control device according to any one of claims 1 to 6.

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