JP2017129022A - Discharge power control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a discharge power control device capable of stabilizing injection timing of an injector.SOLUTION: A charging capacitor 18 charges a boosted voltage of a battery voltage VB, which is boosted by a booster circuit 5. A separation switch 6 can energize/separate between the charging capacitor 18 and a discharging capacitor 7, and when energizing, recharges the voltage charged in the charging capacitor 18 to the discharging capacitor 7. A discharge switch 8 can switch discharge from the discharging capacitor 7 to a coil 3a of an injector 2a, and when discharging, discharges the charged voltage of the discharging capacitor 7 to the coil 3a. In this case, a control IC 4 controls the separation switch 6 to off when applying the voltage to be recharged in the discharging capacitor 7 to the coil 3a of the injector 2a through the discharge switch 8. The charged voltage of the discharge capacitor 7 is not affected even if the booster circuit 5 charges the boosted voltage to the charging capacitor 18.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a discharge power control device used when driving an injector.

  When driving the injector, the electromagnetic valve is driven to control fuel injection (see, for example, Patent Document 1). For example, in the technique described in Patent Document 1, a boost power supply device boosts a battery voltage to charge an output capacitor, and discharges electric energy charged in the output capacitor to a valve opening electric load of the injector. At this time, the charging control circuit operates the charging circuit so that the charging voltage of the output capacitor becomes the target voltage.

  The booster circuit is configured using, for example, a switch element (corresponding to a booster switch), and the power of the power supply voltage is charged / discharged by turning on / off the switch element, and the capacitor is charged with the energy discharged at this time. The charging voltage of this capacitor is reduced by a resistance component (for example, ESR of the output capacitor, detection resistance of the charging current, etc.) existing in the energization path of the current flowing through the coil of the injector (hereinafter referred to as injector current). The voltage applied to the coil decreases. At this time, the charging voltage of the capacitor is detected, and when the detected charging voltage falls below the threshold value, charging is started through the switch element of the booster circuit, that is, charging is started while discharging the accumulated charge of the capacitor.

Japanese Patent Laying-Open No. 2015-50905

  For example, if the energy stored in the inductor of the booster circuit is released to the capacitor immediately before the injector current reaches the peak current threshold, the voltage of the capacitor rapidly increases immediately before it is detected that the peak current threshold is reached. The slope of the peak current changes immediately before the injector current reaches the peak current according to the rapid voltage rise of the capacitor, and the difference in the slope causes the peak current to flow beyond the threshold. There is a risk of becoming faster than the standard. The charging / discharging cycle of the inductor and the slope of the charging current change according to the level of the power supply voltage input to the booster circuit. For this reason, it is difficult to set the energy release timing of the booster circuit so as not to be affected as described above, and the injection start timing varies.

  An object of the present disclosure is to provide a discharge power control apparatus that can stabilize the injection timing of an injector.

  According to invention of Claim 1, it acts as follows. The charging capacitor charges the boosted voltage of the power supply voltage boosted by the booster circuit. The separation circuit is capable of energizing / separating between the charging capacitor and the discharging capacitor, but when energized, the voltage charged in the charging capacitor is recharged into the discharging capacitor. The discharge switching circuit can switch the discharge from the discharge capacitor to the inductive load of the injector. When discharging, the recharge voltage of the discharge capacitor is discharged to the inductive load. Here, the control unit controls the separation circuit to be separated when the voltage recharged to the discharge capacitor is applied to the inductive load of the injector through the discharge switching circuit. That is, when the voltage recharged to the discharge capacitor is applied to the inductive load, the control unit puts the separation circuit into the separation state, so that the boosting operation of the power supply voltage by the boost circuit affects the fluctuation of the voltage across the terminals of the discharge capacitor. There is no longer to do. While the separation circuit is energized, the increase in the current of the inductive load of the injector gradually decreases and does not change rapidly. As a result, even if the charge / discharge cycle of energy and the slope of the charge current according to the ON / OFF operation of the boost switch change according to the level of the power supply voltage, the injection timing can be controlled to the standard timing as much as possible. Can be stabilized.

Electrical configuration diagram schematically showing the configuration of the first embodiment Timing chart schematically showing the operation of the main part Illustration of current flow (part 1) Illustration of current flow (part 2) Timing chart schematically showing changes in voltage and current at the main part when the load current reaches near the peak current threshold Timing chart schematically showing a comparative example corresponding to FIG. Electrical configuration diagram schematically showing the configuration of the second embodiment Timing chart schematically showing the operation of the main part Explanatory diagram for explaining the flow of current

  Hereinafter, some embodiments of a discharge power control device configured inside the fuel injection control device will be described with reference to the drawings. In each embodiment described below, configurations that perform the same or similar operations are denoted by the same or similar reference numerals, and description thereof is omitted as necessary. The following description will be given by using MOS transistors as transistors as various switches, but other types of transistors such as bipolar transistors may be used.

(First embodiment)
FIG. 1 is a schematic block diagram showing an electrical configuration example of an electronic control unit (ECU: Electronic Control Unit) 101 as a fuel injection control device. The electronic control device 101 is a device that drives N solenoid injectors 2 that inject and supply fuel to an N (≧ 1) cylinder engine mounted on a vehicle such as an automobile, for example. The energization start timing and energization time of the coils 3a and 3b as inductive loads are controlled. In this embodiment, an example of N = 2 cylinders is shown.

  As shown in FIG. 1, the electronic control unit 101 includes a control IC 4, a booster circuit 5, a separation switch 6 as a separation circuit, a discharge capacitor 7, a discharge switch 8 as a discharge switching circuit, a constant current switch 9, and a cylinder selection switch 10a. 10b as main components. The electronic control device 101 includes peripheral circuits associated with these main components, such as diodes 11 to 14, current detection resistors R1, R2, and R3. The electronic control device 101 is configured as a discharge power control device.

  The control IC 4 is an integrated circuit device such as an ASIC (Application Specific Integrated Circuit), for example, a logic circuit, a control unit that is a control body such as a CPU, and a memory that is a non-transitional physical recording medium such as a RAM, ROM, or EEPROM. A comparison unit for comparing a predetermined threshold value with the detection currents of the current detection resistors R1, R2, and R3, various amplification units for amplifying signals (none of which are shown), and based on hardware and software It is configured to execute various controls. In particular, the control IC 4 performs on / off control of the boost switch 16, the separation switch 6, the discharge switch 8, the constant current switch 9, and the cylinder selection switches 10a and 10b, and the current flowing through the current detection resistors R1, R2, and R3. The current detection resistors R1, R2, and R3 detect the voltages across the terminals, and execute various controls according to the detection signals.

  In the present embodiment, the coils 3a and 3b of the injectors 2a and 2b for two cylinders are connected to the same common line L1. A booster circuit 5, a separation switch 6, a discharge capacitor 7, a discharge switch 8, and a constant current switch 9 are electrically connected to the one common line L1.

  The booster circuit 5 includes a boost DCDC converter mainly including an inductor 15, a boost switch 16, a diode 17, and a charging capacitor 18, and further includes current detection resistors R2 and R3. The step-up switch 16 is composed of, for example, an N-channel type MOS transistor and is turned on / off from the control IC 4. Between the supply node NB of the battery voltage VB as the power supply voltage and the node NS of the ground potential, the inductor 15, the drain source of the MOS transistor constituting the boost switch 16, and the current detection resistor R2 are connected in series. Yes.

  The terminal voltage of the current detection resistor R2 is input to the control IC 4 so that the control IC 4 can detect the current flowing through the boost switch 16 and the inductor 15. The anode of the diode 17 is connected to the common connection node between the inductor 15 and the boost switch 16, and the charging capacitor 18 and the current detection resistor R3 are connected between the cathode node N1 of the diode 17 and the ground potential node NS. Are connected in series.

  The charging capacitor 18 is composed of, for example, an electrolytic capacitor, and charges power supplied from the inductor 15 through the diode 17. Although the current detection resistor R3 is connected in series with the charging capacitor 18, the voltage across the current detection resistor R3 is input to the control IC4. As a result, the control IC 4 can detect the charging current of the charging capacitor 18.

  A separation switch 6 is configured at the subsequent stage of the charging capacitor 18. The separation switch 6 is configured to be able to energize / separate between the charging capacitor 18 and the discharging capacitor 7, and is configured by an N-channel type MOS transistor in this embodiment. The gate of the transistor constituting the separation switch 6 is connected to the control IC 4, the drain is connected to the cathode of the diode 17, and the source is connected to one terminal of the discharge capacitor 7. The control IC 4 controls the energization on / off between the drain and the source by inputting a control signal to the gate of the transistor of the separation switch 6. The relationship between the ON period of the separation switch 6 and the ON period of the boost switch 16 will be described. For example, the control IC 4 has a unit shorter than the period in which the separation switch 6 energizes between the charging capacitor 18 and the discharging capacitor 7. The boost switch 16 is turned on / off as a cycle.

  A discharge capacitor 7 is formed after the separation switch 6. The discharge capacitor 7 is composed of, for example, an electrolytic capacitor. The discharge capacitor 7 is connected between the source of the MOS transistor constituting the separation switch 6 and the node NS of the ground potential, and is configured separately from the charge capacitor 18. The discharge capacitor 7 can recharge the accumulated charge in the charging capacitor 18. The capacitance value of the discharge capacitor 7 is preferably set smaller than the capacitance value of the charging capacitor 18. As will be described later, the discharge capacitor 7 is recharged with the accumulated charge of the charging capacitor 18. In consideration of the charging and discharging efficiency at this time, the capacitance value of the discharging capacitor 7 is set smaller than the capacitance value of the charging capacitor 18. It is because it is desirable.

  A discharge switch 8 is configured after the discharge capacitor 7. The discharge switch 8 is connected between the discharge capacitor 7 and the coils 3a and 3b, and is configured to be capable of switching the discharge of the accumulated charge of the discharge capacitor 7 from the discharge capacitor 7 to the coils 3a and 3b. In this case, it is composed of an N channel type MOS transistor.

  The gate of the MOS transistor constituting the discharge switch 8 is connected to the control IC 4, the drain thereof is connected to the common connection node N 2 between the source of the transistor constituting the isolation switch 6 and the discharge capacitor 7, and the source is the electronic control device. 101 is connected to an output terminal 1c on the upstream side of 101.

  A constant current switch 9 and a diode 11 are connected in series between the supply node NB of the battery voltage VB and the upstream output terminal 1c. The constant current switch 9 is configured using an N channel type MOS transistor. The gate of the MOS transistor constituting the constant current switch 9 is connected to the control IC 4, the drain is connected to the supply node NB of the battery voltage VB, and the source is connected to the upstream output terminal 1 c of the electronic control device 101. A diode 11 is connected in the forward direction between the source of the transistor of the constant current switch 9 and the output terminal 1c. Further, a reflux diode 12 is connected in the reverse direction between the upstream output terminal 1c and the ground potential node NS.

  Between the upstream terminal 1c and the downstream terminals 1a, 1b of the electronic control device 101, the coils 3a, 3b of the injectors 2a, 2b to be driven are respectively connected. Here, the coils 3a and 3b of the pair of injectors 2a and 2b are connected to one common line L1. A cylinder selection switch 10a is configured between the downstream terminal 1a and the ground potential node NS. A cylinder selection switch 10b is configured between the downstream terminal 1b and the ground potential node NS. These cylinder selection switches 10a and 10b are composed of N-channel MOS transistors.

  The MOS transistor constituting the cylinder selection switch 10a has its drain connected to the terminal 1a and its source connected to one terminal of the current detection resistor R1. The MOS transistor constituting the cylinder selection switch 10b has a drain connected to the terminal 1b, a source connected to one terminal of the current detection resistor R1, and a common connection to the source of the transistor of the cylinder selection switch 10a. ing.

  The current detection resistor R1 is connected in series between the drain and source of the transistors constituting the pair of cylinder selection switches 10a and 10b. The voltage between the terminals of the current detection resistor R1 is input to the control IC 4, and the control IC 4 detects the voltage between the terminals of the current detection resistor R1, thereby information on the current flowing through the cylinder selection switches 10a and 10b and the coils 3a and 3b. Can be obtained.

  A diode 13 is connected in the forward direction between the downstream terminal 1a and the charging node N1 of the charging capacitor 18. For this reason, when the voltage at the terminal 1a on the downstream side rises more than the forward voltage Vf of the diode 13 from the voltage of the charging node N1 of the charging capacitor 18, a current flows through the charging capacitor 18 through the diode 13. The charging capacitor 18 can be charged.

  A diode 14 is also forward-connected between the downstream terminal 1b and the charging node N1 of the charging capacitor 18. For this reason, when the voltage at the terminal 1b on the downstream side rises above the forward voltage Vf of the diode 14 from the voltage at the charging node N1 of the charging capacitor 18, current flows through the diode 14 to the charging capacitor 18, The charging capacitor 18 can be charged. These diodes 13 and 14 are used as a recovery circuit for recovering energy according to the flyback current.

  The operation of the above configuration will be described. FIG. 2 schematically shows the overall flow with a timing chart. Normally, the control IC 4 causes the booster circuit 5 to perform a boost operation in advance in order to inject fuel into each cylinder. At this time, the control IC 4 turns on / off the boost switch 16. When the boost switch 16 is on, the inductor 15 accumulates energy, and when the boost switch 16 is off, the energy of the inductor 15 is charged in the charging capacitor 18. By repeating this operation, the voltage of charging node N1 of charging capacitor 18 rises to reach a predetermined voltage exceeding battery voltage VB. Thereafter, the control IC 4 turns on the transistors constituting the separation switch 6 and controls the separation switch 6 to be in a connected state, thereby charging the discharge capacitor 7 with the boosted voltage. Thus, for example, at the timing t1 in FIG. 2, the charging capacitor 18 and the discharging capacitor 7 are charged with a predetermined boosted voltage.

  When fuel is injected into a cylinder, the control IC 4 outputs the active level “H” of the injection drive signal to the cylinder selection switch 10a corresponding to the cylinder, thereby turning on the cylinder selection switch 10a at timing t2 in FIG. Let At the same time or immediately after this timing t2, the control IC 4 turns off the separation switch 6 to place both ends of the separation switch 6 in a separated state, and turns on the discharge switch 8 simultaneously with or immediately after the timing t2.

  When the cylinder selection switch 10a and the discharge switch 8 are turned on, the charging voltage of the discharge capacitor 7 is discharged to the coil 3a, and the load current of the coil 3a increases as shown at timings t2 to t3 in FIG. The control IC 4 detects the voltage between the terminals of the current detection resistor R1, and detects an increase in the load current of the coil 3a. When the control IC 4 detects that the load current of the coil 3a has reached the peak current threshold value Pt at the timing t3 in FIG. 2, the control IC 4 turns off the discharge switch 8. The control IC 4 puts both ends of the separation switch 6 into a connected state by turning on the separation switch 6 simultaneously or after the discharge switch 8 is turned off at the timing t3.

  By turning on the separation switch 6, the control IC 4 can recharge the boost voltage charged in the charging capacitor 18 into the discharge capacitor 7, and the discharge capacitor 7 is charged as the recharge boost voltage. Further, the control IC 4 can directly charge the discharge capacitor 7 with the boosted voltage generated by the booster circuit 5.

  When the discharge switch 8 is turned off, an induced electromotive voltage is generated at both ends of the coil 3a of the injector 2a. Thereafter, a flyback current is generated in the connection path of the coil 3a. This flyback current flows through the diode 12, the coil 3a of the injector 2a, the diode 13, and the charging capacitor 18, as indicated by an arrow A0 in FIG. That is, when the circuit configuration of the present embodiment is applied, the flyback energy can be recovered in the charging capacitor 18.

  In response to the recovery of the flyback energy, the load current of the coil 3a decreases as shown at timings t3 to t4 in FIG. Thereafter, the control IC 4 turns on the constant current switch 9 so that the load current of the coil 3a detected by the current detection resistor R1 falls within a predetermined constant current range, as shown at timings t4 to t5 in FIG. Control off / on. Thereafter, the control IC 4 sets the injection drive signal of the coil 3a to the non-active level “L”, thereby turning off the cylinder selection switch 10a and stopping the injection control for the cylinder.

  The injection control of a certain cylinder is performed in such a basic flow. Thereafter, when the control IC 4 selects a pair of other cylinders, the cylinder selection switch 10b is turned on, and the separation switch 6, the discharge switch 8, and the constant current switch 9 are turned on / off by the same flow as described above. Thus, as shown at timings t12 to t16 in FIG. 2, a load current similar to the load current of the coil 3a can be applied to the coil 3b. As a result, energization control can be performed on the pair of cylinders, that is, the coils 3a and 3b of the injectors 2a and 2b for two cylinders.

  4 and FIG. 5 for the change timing of the booster switch 16 of the booster circuit 5 and detailed changes in the current and voltage of the main part when the load current of the coil 3a is near the peak current threshold Pt. The details will be described.

  FIG. 4 is illustrated using arrows A1 to A3 for easy understanding of a current path that flows during the time t2 to t3 in FIG. The control IC 4 turns on / off the boost switch 16 with a period shorter than the period when the discharge switch 8 is turned on as a unit period. Therefore, when the control IC 4 turns on the boost switch 16, a current flows as shown by an arrow A1 in FIG. 4, and when the boost switch 16 is turned off, a current flows as shown by an arrow A2 in FIG.

  While the discharge switch 8 is on, the load current of the coil 3a flows from the discharge capacitor 7 through the coil 3a, the cylinder selection switch 10a, and the current detection resistor R1, as indicated by an arrow A3 in FIG. For this reason, at the timings t2 to t3 in FIG. 2, the booster circuit 5 and the discharge capacitor 7 are electrically disconnected, so that the boost pumping operation of the booster circuit 5 affects the fluctuation of the voltage between the terminals of the discharge capacitor 7. There is nothing.

  FIG. 5 shows the load current of the coil 3a, the voltage between the terminals of the discharge capacitor 7, the voltage between the terminals of the charging capacitor 18, and the boost switch 16 when the load current of the coil 3a is close to the peak current threshold Pt. FIG. 6 schematically shows a current when energy is stored in the inductor 15 and a charging current when energy is stored in the charging capacitor 18 by a timing chart.

  As shown in FIG. 5, when the control IC 4 turns on the boost switch 16, the current detected by the current detection resistor R2 rises according to the impedance of the inductor 15 as shown at timings t21 to t22 in FIG. When the switch 16 is turned off, a current corresponding to the energy stored in the inductor 15 flows through the charging capacitor 18 as shown at timings t22 to t23 in FIG. The voltage between the terminals of the charging capacitor 18 instantaneously rises at timing t22 when the energy stored in the inductor 15 flows into the charging capacitor 18. As a result, as shown at timings t21 to t25 in FIG. 5, the control IC 4 can periodically increase the voltage across the charging capacitor 18 by turning on / off the boost switch 16 of the boost circuit 5.

  On the other hand, when the control IC 4 energizes the load current from the discharge capacitor 7 to the coil 3a by turning on the discharge switch 8, as shown at timings t31 to t32 in FIG. 5, the voltage between the terminals of the discharge capacitor 7 is the coil 3a. It continues to decrease due to the power consumption of resistance components (for example, ESR of the discharge capacitor 7 and current detection resistor R1) existing in the energization path. As described above, since the boosting operation of the boosting circuit 5 does not affect the fluctuation of the terminal value voltage of the discharge capacitor 7, as long as the separation switch 6 is off and both ends of the separation switch 6 are in the separated state, the coil The degree of increase in the load current of 3a will gradually decrease, and will not be accompanied by a sudden increase. As a result, even if the charging / discharging cycle of the inductor 15 and the slope of the charging current change according to the level of the battery voltage VB, the injection timing can be controlled to the standard timing as much as possible, and the injection timing can be stabilized.

  For example, when the charging capacitor 18 and the discharging capacitor 7 are integrated and used as a charging capacitor for the booster circuit 5, as shown schematically in FIG. 6, the load of the coil 3a corresponding to the timing chart of FIG. The signal waveform of the current is obtained.

  In the technique shown in FIG. 6, when the charging voltage of the charging capacitor falls below the charging start threshold value Vth at timing t31, the booster circuit 5 controls to turn on the booster switch 16 and starts to energize the inductor 15. Thereafter, when the booster circuit 5 turns off the booster switch 16, the energy of the inductor 15 is energized to the charging capacitor to increase the charging voltage of the charging capacitor.

  At this time, when the boost switch 16 is switched from on to off, the charging current suddenly flows to the charging capacitor at the timing t32 in FIG. 6, and the voltage of the charging capacitor suddenly rises. Since the control IC 4 requires a predetermined circuit delay time T to detect the peak current, when the peak current is detected, the current in the coil 3a actually flows to a current value Pta that is significantly higher than the peak current threshold Pt. It turned out that it was closed. As a result, the injection timing becomes faster than the standard.

  The charging / discharging cycle of the inductor 15 and the slope of the charging current of the charging capacitor change according to the level of the battery voltage VB. For this reason, it is difficult to set the energy release timing of the booster circuit 5 so as not to be affected as described above, and it has been found that the injection start timing varies.

<Summary of this embodiment>
According to the present embodiment, the charging capacitor 18, the discharging capacitor 7, the separation switch 6, and the discharging switch 8 are provided, and the control IC 4 applies a voltage that is recharged to the discharging capacitor 7 to the coil 3 a through the discharging switch 8. When doing so, the separation switch 6 was controlled to be off, and both ends of the separation switch 6 were controlled to be in a separated state. As a result, the boosting operation of the booster circuit 5 does not affect the fluctuation of the voltage between the terminals of the discharge capacitor 7, and the increase in the load current of the coil 3a of the injector 2a is moderated while the separation switch 6 is off. It will decrease, and it will not change rapidly. Therefore, even if the circuit delay time T is required after the load current reaches the peak current threshold value Pt in order for the control IC 4 to detect the peak current, the change is small as shown in the vicinity of the timing t32 in FIG. It becomes current. As a result, even if the charging / discharging cycle of the inductor 15 and the slope of the charging current of the charging capacitor 18 change according to the level of the battery voltage VB, this influence is not affected by the discharging current of the discharging capacitor 7, and the injection timing Can be controlled to the standard timing as much as possible, and the injection timing can be stabilized.

  When the control IC 4 controls the discharge switch 8 to be turned off and the discharge is turned off, the separation switch 6 connected between the charge capacitor 18 and the discharge capacitor 7 is turned on. For this reason, if the booster circuit 5 is performing a boost operation except during the discharge period of the discharge capacitor 7, the boost voltage can be charged to the charge capacitor 18 and the discharge capacitor 7.

  Further, when the capacitance value of the discharge capacitor 7 is set smaller than the capacitance value of the charging capacitor 18, the recharging efficiency from the charging capacitor 18 to the discharging capacitor 7 can be improved.

  Further, since the diodes 13 and 14 as recovery circuits are connected so as to recover the flyback current generated in the coil 3a to the charging capacitor 18 by turning off the discharge switch 8, the power use efficiency can be improved.

(Second Embodiment)
7 to 9 show additional explanatory views of the second embodiment. In this embodiment, a configuration example applied to a fuel injection control device for N = 4 cylinders is shown. The electronic control unit 201 includes a control IC 4, a booster circuit 5, separation switches 61 and 62 as separation circuits, discharge capacitors 71 and 72, discharge switches 81 and 82 as discharge switching circuits, constant current switches 91 and 92, and cylinder selection switches. 101a, 101b, 102a, 102b are provided as main components. The electronic control device 201 includes peripheral circuits associated with these main components, such as diodes 111, 112, 121, 122, 131, 132, 141, 142, and current detection resistors R11, R12.

  As shown in FIG. 7, the configuration of the booster circuit 5 including the charging capacitor 18 is the same as that of the first embodiment, and thus the description thereof is omitted. In the present embodiment, two common lines L1 and L2 are provided. The separation switches 61 and 62, the discharge capacitors 71 and 72, the discharge switches 81 and 82, and the constant current switches 91 and 92 are each provided in parallel. The separation switch 61, the discharge capacitor 71, the discharge switch 81, and the constant current switch 91 are connected to the same common line L1. The separation switch 62, the discharge capacitor 72, the discharge switch 82, and the constant current switch 92 are connected to the same common line L2. The charging capacitor 18 and the separation switches 61 and 62 are connected in common at the node N1, so that the boosted voltage charged in the charging capacitor 18 is recharged in the discharging capacitors 71 and 72 connected to the common lines L1 and L2. It is configured to be possible.

  The common line L1 is connected to coils 31a and 31b of a pair of injectors 21a and 21b through a terminal 11c, and a pair of cylinder selection switches 101a and 31b are connected to the coils 31a and 31b of the injectors 21a and 21b. 101b is provided. The common line L2 is connected to the coils 32a and 32b of the pair of injectors 22a and 22b through the terminal 12c, and the pair of cylinder selection switches 102a and so on correspond to the coils 32a and 32b of the injectors 22a and 22b. 102b is provided.

  The coils 31a and 31b of the injectors 21a and 21b are commonly connected to the upstream terminal 11c, and the coils 32a and 32b of the injectors 22a and 22b are commonly connected to the upstream terminal 12c. Further, the coils 31a and 31b of the injectors 21a and 21b are connected to the terminals 11a and 11b on the downstream side, respectively. Further, the coils 32a and 32b of the injectors 22a and 22b are connected to the terminals 12a and 12b on the downstream side, respectively.

  Cylinder selection switches 101a and 101b are connected between the downstream terminals 11a and 11b and the ground potential node NS, respectively. Cylinder selection switches 102a and 102b are connected between the downstream terminals 12a and 12b and the ground potential node NS, respectively.

  In addition, diodes 131 and 141 are connected in the forward direction between the terminals 11a and 11b on the downstream side and the charging node N1 of the charging capacitor 18. Further, diodes 132 and 142 are connected in the forward direction between the downstream terminals 12a and 12b and the charging node N1 of the charging capacitor 18.

  The current detection resistor R11 is provided corresponding to the coils 31a and 31b of the pair of injectors 21a and 21b connected to the same common line L1, and is connected in series to the pair of cylinder selection switches 101a and 101b. Similarly, the current detection resistor R12 is provided corresponding to the coils 32a and 32b of the pair of injectors 22a and 22b connected to the same common line L2, and is connected in series to the pair of cylinder selection switches 102a and 102b. Yes. The voltage between the terminals of these current detection resistors R11 and R12 is input to the control IC 4. Each element has the same configuration as that of the first embodiment. In this embodiment, each element corresponds to a configuration in which two pairs exist, and therefore, parts having the same function are denoted by the same reference numerals 10. A reference numeral multiplied by is added to 10 or more places, and “1” and “2” are added to the first place of the reference numerals, and a basic configuration description and a functional description thereof are omitted.

  The operation of the above-described configuration will be described focusing on the differences from the first embodiment. In the present embodiment, one charging capacitor 18 is configured, and the subsequent separation switches 61 and 62, discharge capacitors 71 and 72, and discharge switches 81 and 82 are configured one by one on the two common lines L1 and L2. Yes. For this reason, it is desirable that the charging capacitor 18 is set to a capacity value for accumulating boost energy for sufficiently driving the coils 31a, 31b, 32a, and 32b of the injectors 21a, 21b, 22a, and 22b for four cylinders. However, when the supply capability of the boosted voltage by the charging capacitor 18 is reduced, it is desirable that the booster circuit 5 recharges the charging capacitor 18 until the charging capability is reduced.

  In particular, when the control IC 4 performs the injection control process by alternately switching the injectors 21a, 21b, 22a and 22b connected to the common lines L1 and L2, the two common lines L1 and L2 are connected. When the flyback energy is recovered in one common line (for example, L1), the boost voltage is supplied from the booster circuit 5 to the coil (for example, 32b) in the other common line (for example, L2). Therefore, it is desirable to quickly switch the injector to be controlled. In such a case, since the boosted voltage of the booster circuit 5 may be greatly reduced, it is desirable to charge the charging capacitor 18 quickly, and it is desirable to operate each circuit using the following procedure.

  FIG. 8 schematically shows the overall flow with a timing chart. First, the control IC 4 causes the booster circuit 5 to perform a boost operation in order to inject fuel into each cylinder. Therefore, the control IC 4 turns on / off the boost switch 16 and raises the charging voltage of the charging capacitor 18 so as to reach a predetermined voltage exceeding the battery voltage VB. At this time, as shown at timing t41 in FIG. 8, the control IC 4 controls the separation switches 61 and 62 to turn on the separation switches 61 and 62 so that the discharge capacitors 71 and 72 are also charged with the boosted voltage. . As a result, the charging capacitor 18 and the discharging capacitors 71 and 72 are charged with a predetermined boosted voltage set in advance.

  When the control IC 4 injects fuel into a predetermined first cylinder by energizing the coil of the injector 21a connected to the one common line L1, as shown at timing t42 in FIG. 8, the active level of the injection drive signal By outputting “H” to the control terminal of the cylinder selection switch 101a corresponding to the predetermined first cylinder, the cylinder selection switch 101a is turned on. At the same time or immediately after this timing t42, the control IC 4 turns off the separation switch 61, and turns on the discharge switch 81 at the same time or immediately after this timing t42.

  When the cylinder selection switch 101a and the discharge switch 81 are turned on, the charging voltage of the discharge capacitor 71 is discharged to the coil 31a, and the load current of the coil 31a increases as indicated by timings t42 to t43 in FIG. The control IC 4 detects the load current of the coil 31a by detecting the voltage between the terminals of the current detection resistor R11. When the control IC 4 detects that the load current of the coil 31a has reached the peak current threshold value Pt at the timing t43 in FIG. 8, the control IC 4 turns off the discharge switch 81. The control IC 4 turns on the separation switch 61 at the same time or after the discharge switch 81 is turned off. When the control IC 4 turns on the separation switch 61, the charging voltage charged in the charging capacitor 18 can be recharged in the discharging capacitor 71. Further, the booster circuit 5 can directly charge the discharge capacitor 71 with the boosted voltage.

  Even when the control IC 4 switches off the discharge switch 81 to discharge off the discharge capacitor 7, a voltage is generated at both ends of the coil 31a of the injector 21a. Therefore, even after the discharge switch 81 is turned off, the coil 31a. Produces a flyback current. This flyback current flows through the path of the diode 121, the coil 31a of the injector 21a, the diode 131, and the charging capacitor 18, as indicated by an arrow A4 in FIG. That is, when the circuit configuration of the present embodiment is applied, the flyback energy can be recovered in the charging capacitor 18. Since the separation switch 61 connected to the common line L1 is on, the flyback current also flows to the discharge capacitor 71 connected to the subsequent stage of the separation switch 61. Back energy can be recovered. As the flyback energy is recovered, the load current of the coil 31a decreases. Thereafter, the control IC 4 performs control so that the load current detected by the current detection resistor R11 falls within a predetermined constant current range. To do.

  On the other hand, for example, while recovering this flyback energy, the control IC 4 energizes the coil 32b of the injector 22b connected to the other common line L2 while keeping the cylinder selection switch 101a of the predetermined first cylinder ON. Thus, fuel is injected into a predetermined second cylinder. At this time, the control IC 4 outputs the active level “H” of the injection drive signal of the coil 32b to the control terminal of the cylinder selection switch 102b corresponding to the predetermined second cylinder, as shown at timing t44 in FIG. The cylinder selection switch 102b is turned on.

  Further, the control IC 4 turns on the discharge switch 82 simultaneously with or immediately after the timing t44. When the cylinder selection switch 102b and the discharge switch 82 are turned on, the charging voltage of the discharge capacitor 72 is discharged to the coil 32b of the injector 22b and the load current of the coil 32b of the injector 22b as shown at timings t44 to t45 in FIG. Rises. At this time, the separation switch 62 of the common line L2 is turned off, so that both ends of the separation switch 62 are separated. For this reason, the load current applied to the coil 32b of the injector 22b by the discharge capacitor 72 is not affected by the boosting operation of the booster circuit 5, and the current flow is as shown by the arrow A5 in FIG. It is not affected by the flyback current flowing in the common line L1. For this reason, the discharge current can be stabilized.

  When the booster circuit 5 applies the boosted voltage to the coil 32b of the injector 22b of the second cylinder, the charging capacitor 18 is applied in accordance with the application of the boosted voltage to the coil 31a of the injector 21a of the first cylinder performed immediately before that. Although there is a possibility that the voltage between the terminals is lowered, also in this embodiment, the booster circuit 5 separates the charging capacitor 18 and the discharging capacitor 72 by the separation switch 62 as shown in FIG. During this time, the voltage between the terminals of the charging capacitor 18 is charged. For this reason, the charging capacitor 18 can be charged independently even during the discharging of the discharging capacitor 72. For this reason, even if the control IC 4 is controlled to discharge continuously from the discharge capacitors 71 and 72 so as to perform the proximity multi-stage injection process, the discharge capacity of these discharge capacitors 71 and 72 is held so as not to be reduced as much as possible. be able to. As a result, the load current to the coils 31a and 32b of the injectors 21a and 22b can be sufficiently increased. Since the subsequent operation is the same as that of the previous embodiment, the description of the basic operation is omitted. As a result, the energization control can be performed on the two pairs of cylinders, that is, the coils 31a, 31b, 32a, and 32b of the injectors 21a, 21b, 22a, and 22b for the four cylinders by using a so-called proximity multistage injection technique.

  For example, if the conventional technique is applied, if the booster circuit stops the charge control during discharging from the discharge capacitor, there is a risk that the charging capability may be insufficient at the time of proximity multistage injection, but according to the present embodiment, the discharge capacitor 71, Since the separation switches 61 and 62 are turned off when discharging from the coil 72 to the coils 31a and 32b, the booster circuit 5 applies the boosted voltage to the charging capacitor 18 while discharging from the discharge capacitors 71 and 72, respectively. Will be able to charge. Thereby, the influence of the boosting timing of the booster circuit 5 does not affect the charged state of the discharge capacitors 71 and 72, and the same effect as the above-described embodiment is obtained.

  While the discharge capacitor 72 connected to the common line L2 is discharging, the flyback energy generated in the coil 31a through the path of the arrow A4 shown in FIG. Further, when collecting the current generated in the common line L1, the control IC 4 controls the separation switch 62 connected to the common line L2 to be turned off. For this reason, even during the discharge of the discharge capacitor 72 connected to the common line L1, the electric power corresponding to the flyback current flowing through the common line L1 can be properly recovered by the charging capacitor 18.

(Other embodiments)
The present invention is not limited to the above-described embodiments, can be implemented with various modifications, and can be applied to various embodiments without departing from the gist thereof. For example, the following modifications or expansions are possible. The plurality of embodiments described above can be combined.

  Various control devices may be used instead of the control IC 4. The means and / or functions provided by the control device can be provided by software recorded in a substantial memory device and a computer that executes the software, software, hardware, or a combination thereof. For example, when the control device is provided by an electronic circuit that is hardware, the control device can be configured by a digital circuit including one or a plurality of 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 a method corresponding to the program is executed when the control subject executes the program.

In the above-described embodiment, for the sake of simplification of description, the description is given by indicating injectors for two cylinders and four cylinders, but the same contents can be implemented in the case of other cylinders such as six cylinders.
In the above-described embodiment, the “separation circuit” is configured by the separation switches 6, 61, and 62 using a single N-channel type MOS transistor, but the type of transistor is not limited, and other elements are included. You may comprise combining. In the above-described embodiment, the “discharge switching circuit” is configured by the discharge switches 8, 81, 82 formed of a single N-channel MOS transistor. However, the type of the transistor is not limited, and other resistors, etc. These elements may be combined. Similarly, the “collection circuit” may employ other circuit configurations regardless of the single diodes 13, 14, 131, 132, 141, 142.

  In the second embodiment, while the flyback energy generated in the coil 31a of the injector 21a connected to one common line L1 is being recovered, the coil of the injector 22b connected to the other common line L2 is discharged from the discharge capacitor 72. Although the control is performed so as to discharge to 32b, this indicates the worst case, and when there is a time margin, for example, constant current control of the coil 31a of the injector 21a connected to one common line L1 is performed. During the operation, the discharge capacitor 72 may be controlled to discharge to the coil 32b of the injector 22b connected to the other common line L2. Even in such a case, the same effects as those of the above-described embodiment can be obtained.

  The reference numerals in parentheses described in the claims indicate the correspondence with the specific means described in the embodiment described above as one aspect of the present invention, and the technical scope of the present invention is It is not limited.

  In the drawings, 101 and 201 are electronic control devices (discharge power control devices), 2a, 2b, 21a, 21b, 22a and 22b are injectors, 3a, 3b, 31a, 31b, 32a and 32b are coils (inductive loads), 4 is a control IC (control unit), 5 is a booster circuit, 6, 61 and 62 are separation switches (separation circuits), 7, 71 and 72 are discharge capacitors, 8, 81 and 82 are discharge switches (discharge switching circuits), Reference numerals 13, 14, 131, 141, 132, and 142 denote diodes (recovery circuits), 18 denotes a charging capacitor, and L1 and L2 denote common lines.

Claims (6)

A booster circuit (5) comprising a charging capacitor (18) that charges and discharges energy according to ON / OFF of the booster switch (16) to boost the power supply voltage and charges the boosted voltage;
A discharge capacitor (7; 71, 72) provided separately from the charge capacitor and capable of recharging the boosted voltage of the charge capacitor;
Separating between the charging capacitor and the discharging capacitor and configured to energize / separate between the charging capacitor and the discharging capacitor, and to recharge the boost voltage of the charging capacitor to the discharging capacitor when energized A circuit (6; 61, 62);
Connected between the discharge capacitor and the inductive load (3a, 3b; 31a, 31b, 32a, 32b) of the injector (2a, 2b; 21a, 21b, 22a, 22b) from the discharge capacitor to the inductive load A discharge switching circuit (8; 81, 82) configured to be able to switch between discharges and discharging a charging voltage of the discharge capacitor to the inductive load when discharging;
A control unit (4) for controlling the separation circuit and the discharge switching circuit,
The control unit is a discharge power control device that controls to separate the separation circuit when a voltage recharged to the discharge capacitor is applied to the inductive load through the discharge switching circuit. The discharge power control device according to claim 1,
The control unit is configured to control the discharge switching circuit to turn off the discharge, and when the recharge boost voltage is not applied to the inductive load, the separation circuit connected between the charge capacitor and the discharge capacitor. A discharge power control device that controls to energize. In the discharge power control device according to claim 1 or 2,
A discharge power control device in which a capacitance value of the discharge capacitor is smaller than a capacitance value of the charge capacitor. The discharge power control device according to claim 1,
The control unit further includes a recovery circuit (13, 14; 131, 141, 132, 142) for recovering a flyback current generated in the inductive load to the charging capacitor by controlling the discharge switching circuit to be turned off. Discharge power control device. The discharge power control device according to claim 1,
One discharge capacitor (71), the separation circuit (61), and the discharge switching circuit (81) are connected to one common line (L1), and the other discharge capacitor (72), the separation The circuit (62) and the discharge switching circuit (82) are connected to another common line (L2),
The boost voltage of the charge capacitor of the boost circuit is configured to be rechargeable to the discharge capacitors (71, 72) connected to the one and other common lines,
The control unit controls the one or other discharge switching circuit (81, 82) to be turned off, thereby collecting a flyback current generated in the inductive load in the charging capacitor (131, 141, 132, 142). In the discharge power control device according to claim 5,
The control unit controls the discharge switching circuit (81) connected to the one common line (L1) to discharge off, thereby collecting flyback current generated in the inductive load in the recovery circuit (131, 141). A discharge power control device that controls to separate the separation circuit (62) connected to the other common line when the charging capacitor collects the battery.

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