JP2019019778A - Electronic control device - Google Patents

Abstract

To provide an electronic control device which can drive-control a fuel injection valve and the other actuator at favorable performance while suppressing circuit noise.SOLUTION: A charge switch T2 is electrically connected to a piezoelectric injector 51, and charges a first boost voltage of a first boost circuit 14 to the piezoelectric injector 51 via a coil L2 in order to valve-open the piezoelectric injector 51. A discharge switch T3 discharges an electrical charge accumulated in the piezoelectric injector 51 via the coil L2 in order to valve-close the piezoelectric injector 51. A second boost circuit 15 is arranged for driving a pump 4, and creates a second boost voltage Vboost2 which is higher than a power supply voltage in accordance with a first boost voltage Vboost1 of the first boost voltage 14. The second boost circuit 15 comprises the coil L2, the discharge switch T3, a charge capacitor C2 for charging the second boost voltage Vboost2, a backflow prevention boost switch T5 arranged between the coil L2 and the charge capacitor C2, and a diode D2.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an electronic control unit that controls an injection valve and drives another actuator.

  2. Description of the Related Art Conventionally, an electronic control device for controlling fuel injection by using a displacement type fuel injection valve in an internal combustion engine is known. This type of electronic control device drives a displacement type fuel injection valve. The battery voltage and a high voltage obtained by boosting the battery voltage are used. In recent years, improvement in injection performance has been demanded, and there is a demand for adopting a high-pressure pump (HPFP) and applying a high voltage using a booster circuit to suppress variation in discharge amount.

JP2013-99169A

  For example, in order to drive these fuel injection valves and other actuators with good performance, it is sometimes necessary to change the boosted voltage values. For this reason, each of the booster circuits has been provided individually to generate different boosted voltage values so far, but preparing two systems of booster circuits requires preparing two parts of large components such as coils, This hinders downsizing of the control device.

  Therefore, the inventor tries to reduce the size of the electronic control device by sharing these booster circuits. However, when driving and controlling fuel injection valves and other actuators, it is desired to supply the required boosted voltage value at the required timing. May not be achieved satisfactorily.

  An object of the disclosure of the present invention is to provide an electronic control device capable of controlling the fuel injection valve and other actuators with high performance while suppressing the circuit size.

  The invention described in claim 1 is directed to an electronic control device that drives a capacitive fuel injection valve and an actuator other than the fuel injection valve. According to the first aspect of the present invention, the first booster circuit is provided for driving the fuel injection valve and can supply the first boosted voltage obtained by boosting the power supply voltage. The charging switch is electrically connected to the fuel injection valve and is provided to charge the capacitive fuel injection valve through the coil with the first boosted voltage of the first booster circuit in order to open the fuel injection valve. The discharge switch is provided to discharge the electric charge accumulated in the capacitive fuel injection valve through the coil in order to close the fuel injection valve.

  The second booster circuit is provided for driving another actuator, and generates a second boosted voltage higher than the power supply voltage in accordance with the first boosted voltage of the first booster circuit. The second booster circuit includes the coil, a discharge switch, a charging capacitor for charging the second boosted voltage, and a booster switch and a diode for preventing a backflow provided between the coil and the charging capacitor. Configured.

  Therefore, since the second booster circuit can be configured to share a coil used when energizing the capacitive fuel injection valve, the circuit size can be suppressed as much as possible. Since the first and second booster circuits generate the first and second boosted voltages, respectively, when driving and controlling the fuel injection valve and other actuators, the required boosted voltage value can be supplied at the required timing, and the fuel injection Actuators other than the valve and the fuel injection valve can be driven with good performance.

Configuration example of fuel injection system in first embodiment Electrical configuration diagram of the electronic control device in the first embodiment Timing chart according to pump drive in the first embodiment Timing chart for normal injection control in the first embodiment Electrical configuration diagram of electronic control device in second embodiment Timing chart for boost control at start-up in the second embodiment

  Hereinafter, some embodiments of the electronic control device will be described with reference to the drawings. In each embodiment described below, the same or similar reference numerals are given to configurations that perform the same or similar operations. In the description of the second embodiment, the description of the same or similar configuration and the same or similar operation described in the first embodiment will be omitted as necessary.

(First embodiment)
1 to 4 are explanatory diagrams of the first embodiment. FIG. 1 shows a configuration example of a fuel injection system 1 for a four-cylinder internal combustion engine. This fuel injection system 1 includes an electronic control unit (ECU) 2, a high pressure pump (hereinafter abbreviated as a pump) 4 for supplying fuel to a common rail 3, and a fuel injection valve for four cylinders. The piezoelectric injectors 51 to 54 are connected.

  The electronic control device 2 drives, for example, four piezo injectors 51 to 54 that inject and supply fuel to an internal combustion engine 6 such as a diesel engine mounted on a vehicle such as an automobile. The electronic control device 2 basically drives the piezo injectors 51 to 54 for a plurality of cylinders such as four cylinders, but the basic drive system of the piezo injectors 51 to 54 for each cylinder is the same, so the description is simplified. For the sake of simplicity, FIG. 2 shows a circuit for driving the piezo injector 51 for one cylinder. As shown in FIG. 2, the piezo injector 51 includes a piezo element P1, and the piezo element P1 has a capacitance characteristic. For this reason, the driving / non-driving of the piezo injector 51 is performed by charge / discharge. The electronic control device 2 shown in FIG. 2 is configured to charge / discharge electric charges in the piezo element P1 of the piezo injector 51, thereby controlling the fuel injection timing by the piezo injector 51.

  As shown in FIG. 1, the pump 4 is configured to pump fuel from the fuel tank 8, and accumulates and pressurizes the fuel inside the common rail 3. The electronic control unit 2 controls an electromagnetically driven intake metering valve (not shown) provided in the fuel intake part of the pump 4 according to the energization of the electromagnetic coil 71 (see FIG. 2). As a result, The pressure of the common rail 3 is controlled to a pressure within a predetermined range by the pump 4. The common rail 3 is provided with an electromagnetically driven pressure reducing valve 9 for reducing the fuel pressure. The electronic control unit 2 shown in FIG. 2 also includes a drive circuit for the pressure reducing valve 9, but the drive system for the pressure reducing valve 9 is the same as the drive system for the pump 4 and is the same as the drive circuit for the pump 4. It is the composition. For this reason, the electrical configuration is omitted in FIG.

  As shown in FIG. 1, the electronic control unit 2 detects the fuel pressure with a pressure sensor 10 installed on the common rail 3, and when the fuel pressure inside the common rail 3 exceeds a specified value, an electromagnetic coil (not shown) The pressure reducing valve 9 is opened in accordance with the energization control to), so that the fuel inside the common rail 3 is returned to the return pipe (not shown) and returned to a pressure within a predetermined range.

  A crank angle sensor 11 is installed in the internal combustion engine 6. The crank angle sensor 11 is provided as a sensor for detecting a driving state, and outputs a crank angle signal every time the crank rotates by a predetermined angle. The electronic control unit 2 can calculate the engine speed according to the crank angle signal of the crank angle sensor 11. Although not shown, in the vehicle, an accelerator sensor that detects an accelerator opening that is an operation amount of an accelerator pedal by a driver, and a temperature sensor that detects temperatures of various media (for example, cooling water and intake air). The electronic control unit 2 inputs these sensor signals S and executes control processing based on the sensor signals S.

  As shown in FIG. 2, the electronic control unit 2 can supply the first boosted voltage Vboost1 for boosting the power supply voltage (corresponding to the reference voltage) VB by the microcomputer 12, the control IC 13, and the battery to drive the piezo injector 51. And a second booster circuit 15 for generating a second boosted voltage Vboost2 for driving the pump 4.

  The first boost circuit 14 includes a coil L1, a boost switch T1 for boost driving, a diode D1, and a boost DCDC converter including a first charging capacitor C1, and generates a first boost voltage Vboost1. The first booster circuit 14 stores the first boosted voltage Vboost1 obtained by boosting the power supply voltage VB in the first charging capacitor C1.

  Further, the electronic control unit 2 drives the piezo injector 51 using the charging voltage stored in the first charging capacitor C1, so that the charging switch T2, the discharging switch T3, the cylinder selection switch T4, and the charging / discharging coil L2 are provided. Prepare. The charge switch T2 is a switch for charging the piezo element P1 of the piezo injector 51, and the discharge switch T3 is a switch for discharging the charge from the piezo element P1 of the piezo injector 51. The cylinder selection switch T4 is a switch for selecting one piezo injector 51 from the piezo injectors 51 to 54 for four cylinders. The charge / discharge coil L2 is provided to supplement the coil resistance component when driving the piezo injector 51 and to control the charge / discharge charge amount.

  Further, the electronic control device 2 includes a second booster circuit 15 for driving the electromagnetic coil 71 of the pump 4. The second booster circuit 15 operates using the charging / discharging coil L2 in consideration of technical effects, and further operates by connecting the booster switch T5, the diode D2, and the second charging capacitor C2. Further, since the electronic control unit 2 drives the pump 4 using the charging voltage stored in the second charging capacitor C2, the main component is the pump constant current switch T6, the pump driving switch T7, and the pump selection switch T8. Prepare. The pump constant current switch T6 is a switch provided to drive the electromagnetic coil 71 of the pump 4 at a constant current. The electronic control unit 2 includes peripheral circuits associated with these main components, for example, diodes D3 to D5.

  The microcomputer 12 receives the sensor signal S described above, generates various command signals (for example, a boost start command signal, an injection command signal, and a pressure adjustment command signal) and outputs them to the control IC 13. The control IC 13 is, for example, an ASIC integrated circuit device, and includes a control body such as a logic circuit and CPU, and a storage unit such as a RAM, ROM, and EEPROM, and executes various controls based on hardware and software. In particular, it receives various command signals from the microcomputer 12 and executes control.

<Specific connection explanation>
As described above, the first booster circuit 14 includes the coil L1, the booster switch T1, the diode D1, and the first charging capacitor C1. The step-up switch T1 is composed of, for example, an N-channel type MOS transistor, and is on / off controlled by the control IC 13.

  Between the supply node NB of the power supply voltage VB and the ground node NS, the coil L1 and the drain and source of the MOS transistor constituting the boost switch T1 are connected in series. The anode of the diode D1 is connected to the common connection node Nm between the coil L1 and the booster switch T1, and the first charging capacitor C1 is connected between the cathode node N1 of the diode D1 and the ground node NS. Yes. The first charging capacitor C1 is composed of, for example, an aluminum electrolytic capacitor, and charges the power supplied from the coil L1 through the diode D1. Although the detection connection is not shown in FIG. 2, the voltage across the first charging capacitor C1 is input to the control IC 13, and the control IC 13 charges the charging voltage of the first charging capacitor C1, that is, the first boosting voltage. The voltage Vboost1 can be detected. The voltage Vboost1 of the first charging capacitor C1 is prepared for driving the piezo injector 51.

  The charge switch T2 and the discharge switch T3 are each configured by, for example, an N-channel MOS transistor, and are on / off controlled by the control IC 13. Between the charge node N1 of the first charging capacitor C1 and the ground node NS, a series connection is made between the drain and source of the MOS transistor constituting the charge switch T2 and between the drain and source of the MOS transistor constituting the discharge switch T3. Has been.

  The charge switch T2 is provided for accumulating electric charge in the piezo element P1 of the piezo injector 51, and is turned on by the control IC 13 when accumulating electric charge in the piezo element P1. The discharge switch T3 is provided for discharging the charge accumulated in the piezo element P1 of the piezo injector 51, and is turned on by the control IC 13 when discharging the accumulated charge from the piezo element P1.

  A charge / discharge coil L2 is connected between the common connection node N2 of the charge switch T2 and the discharge switch T3 and the upstream terminal 2a. A piezo element P1 of the piezo injector 51 is connected between the upstream terminal 2a and the downstream terminal 2b, and a cylinder selection switch T4 and a current detection resistor (not shown) are connected between the downstream terminal 2b and the ground node NS. ) Is connected. This cylinder selection switch (equivalent to a selection switch) T4 is constituted by, for example, an N-channel MOS transistor, and is on / off controlled by the control IC 13.

  As described above, the second booster circuit 15 is configured by using the charge / discharge coil L2 in view of technical operation, and further includes the booster switch T5, the diode D2, and the second charging capacitor C2. And is configured to perform a boost operation.

  The step-up switch T5 is composed of, for example, a P-channel type MOS transistor, and is on / off controlled by the control IC 13. Between the node N2 and the ground node NS are connected in series between the source and drain of the MOS transistor constituting the boost switch T5, between the anode and cathode of the diode D2, and the second charging capacitor C2. The voltage Vboost2 of the second charging capacitor C2 is prepared for driving the pump 4 (and the pressure reducing valve 9). If both the first and second charging capacitors C1 and C2 are fully charged, the first boosted voltage Vboost1 is significantly higher than the second boosted voltage Vboost2.

  The second charging capacitor C2 is also composed of, for example, an aluminum electrolytic capacitor, and charges power supplied from the node N2 through the boost switch T5 and the diode D2. Although not shown, the voltage between the terminals of the second charging capacitor C2 is input to the control IC 13, so that the control IC 13 can detect the charging voltage of the second charging capacitor C2, that is, the boost voltage Vboost2. . Considering the circuit connection, when the boost switch T5 is turned on by the control IC 13, it is connected so as to be energized in one direction from the node N2 to the second charging capacitor C2, thereby preventing the reverse flow in the reverse direction. Can do.

  On the other hand, the pump drive switch T7 is composed of, for example, an N-channel MOS transistor, and is on / off controlled by the control IC 13. Between the charging node N3 of the charging voltage Vboost2 of the second charging capacitor C2 and the upstream terminal 2c, the drain and source of the MOS transistor constituting the pump drive switch T7 are connected. The pump drive switch T7 is provided to supply the second boosted voltage Vboost2 to the electromagnetic coil 71 for driving the pump 4.

  Further, the pump constant current switch T6 is configured by, for example, an N-channel MOS transistor, and is controlled to be turned on / off by the injection control IC 13. Further, between the supply node NB of the power supply voltage VB and the upstream terminal 2c, the drain and source of the MOS transistor constituting the pump constant current switch T6 and the anode and cathode of the diode D3 are connected. A reflux diode D4 is connected in the reverse direction between the upstream terminal 2c and the ground node NS. An electromagnetic coil 71 of the pump 4 is connected between the upstream terminal 2c and the downstream terminal 2d.

  A pump selection switch T8 is connected between the downstream terminal 2d and the ground node NS. The pump selection switch T8 is a switch provided for selecting driving of the pump 4. The pump selection switch T8 is composed of, for example, an N channel type MOS transistor, and is ON / OFF controlled by the control IC 13. The drain of the MOS transistor constituting the pump selection switch T8 is connected to the downstream terminal 2d, and the source is connected to the ground node NS through a current detection resistor (not shown). A diode D5 is connected in the forward direction between the downstream terminal 2d and the charging node N3 of the second charging capacitor C2.

  For this reason, when the voltage of the downstream terminal 2d rises above the forward voltage Vf of the diode D5 from the voltage of the node N3 of the second charging capacitor C2, the current flows to the second charging capacitor C2 through the diode D5. Electric power can be collected in the second charging capacitor C2. The diode D5 is used as a recovery circuit that recovers energy according to the flyback current. In this configuration, the control IC 13 performs on / off control of the boost switches T1 and T5, the charge switch T2, the discharge switch T3, the cylinder selection switch T4, the pump constant current switch T6, the pump drive switch T7, and the pump selection switch T8. Various controls are executed.

  In particular, when the control IC 13 performs boost control of the first charging capacitor C1, the first boost voltage Vboost1 is boosted by turning on / off the boost switch T1. When the control IC 13 performs step-up control of the second charging capacitor C2, the second boosted voltage Vboost2 is generated using the discharging action of the piezo injector 51. The control IC 13 drives and controls the piezo injector 51 and the pump 4 using the first and second boosted voltages Vboost1 and Vboost2.

The operation and operation of the above configuration will be described.
As usual, when a power switch (not shown) such as an ignition switch is turned on by the driver and the power supply voltage VB is turned on, the control IC 13 performs an injection control process in cooperation with the microcomputer 12. Usually, before the injection control is started, the first and second charging capacitors C1 and C2 are charged so as to exceed the full charge thresholds Vbt1 and Vbt2. Hereinafter, the voltage charged to the full charge thresholds Vbt1 and Vbt2 is referred to as a full charge voltage.

<Basic pump drive control>
First, a basic drive control process of the electromagnetic coil 71 of the pump 4 will be described with reference to FIG. For example, when the electronic control unit 2 injects fuel from the piezo injector 51, the fuel pressure accumulated in the common rail 3 decreases. At this time, the electronic control unit 2 detects the fuel pressure by the pressure sensor 10, and increases the fuel pressure by driving the pump 4 when the fuel pressure is reduced to a pressure lower limit threshold value or less. As a result, the fuel pressure is adjusted to be within a predetermined range. When the pump 4 is driven, the microcomputer 12 outputs a pressure adjustment command signal to the injection control IC 13 to energize the electromagnetic coil 71 to operate the pump 4.

  When the control IC 13 receives the active level “H” of the pump drive command signal as the pressure adjustment command signal, the control IC 13 turns on the pump selection switch T8 and turns on the pump drive switch T7, so that the second boosted voltage Vboost2 is The electromagnetic coil 71 is energized. The control IC 13 turns off the pump drive switch T7 when the pump drive current Ipu reaches the peak threshold value. Thereafter, the pump driving current Ipu decreases, but when the pump driving current Ipu reaches a constant current range lower than the peak threshold, the pump constant current switch T6 is controlled to be turned on / off to hold the pump driving current Ipu in a certain range. . As a result, the operation of the pump 4 is maintained. And control IC13 will stop operation | movement of the pump 4 by turning off all the switches T6-T8, if the pump drive command signal of a pressure adjustment command signal is received as a non-active level.

  In such a series of operations, as shown in FIG. 3, when the control IC 13 receives the active level “H” of the pump drive command signal and turns on the pump drive switch T7, it accumulates in the second charging capacitor C2. The second boosted voltage Vboost2 is reduced due to the consumption of the charged power, but when the second boosted voltage Vboost2 falls, the second boosted voltage Vboost can be started by raising the charge request flag when the charge request threshold Vbu2 is reached. To. In the present embodiment, charge control is performed on the second charging capacitor C2 during the injection control process on the condition that the charge request flag is set. This will be described below.

<Injection control>
The injection control process will be described with reference to FIG. When the electronic control unit 2 injects fuel from the piezo injector 51, the microcomputer 12 outputs an active level “H” of an injection command signal corresponding to the piezo injector 51 to the control IC 13 at timing t1 in FIG.

  When receiving the active level “H” of the injection command signal, the control IC 13 turns on the cylinder selection switch T4 while turning on the charging switch T2. The charging switch T2 may be subjected to on / off pulse control. When the charging switch T2 and the cylinder selection switch T4 are turned on, the applied voltage to the piezo element P1 rises and the nozzle of the piezo injector 51 is opened to the maximum position. When a predetermined charge stop condition is satisfied, the control IC 13 stops the on control of the charge switch T2 and performs the off control. Various conditions can be applied to the predetermined charging stop condition in consideration of the condition that the charging process of the piezo element P1 is sufficiently performed, and the description thereof is omitted.

  Then, the control IC 13 holds the state where the charging switch T2 is turned off until the injection command signal is accepted as the non-active level “L”. As a result, fuel is injected into the cylinder of the internal combustion engine 6.

  Thereafter, when the microcomputer 12 outputs the injection command signal as the non-active level “L” to the control IC 13 at the timing t3 in FIG. 4, the control IC 13 receives the non-active level of the injection command signal. Then, the control IC 13 turns on the boost switch T5 and starts on / off chopper control of the discharge switch T3.

  When the control IC 13 performs chopper control of the discharge switch T3, the electric charge accumulated in the piezo element P1 is discharged. At this time, the control IC 13 repeatedly applies an ON control signal to the gate of the discharge switch T3 in the period t3 to t4 in FIG. For this reason, the electric charge accumulated in the piezo element P1 is discharged in a pulse shape, and the nozzle of the piezo injector 51 is gradually closed. At this time, since the boost switch T5 is turned on, the accumulated charge of the piezo element P1 is recovered by the second charging capacitor C2 through the boost switch T5 and the diode D2 by the action of the induced electromotive force of the charge / discharge coil L2.

  Specifically, when the discharge switch T3 is turned on, the charge accumulated between both terminals of the piezo element P1 is discharged through the discharge switch T3. However, when the discharge switch T3 is turned off, the charge / discharge coil L1 is discharged. Current flowing between both terminals is instantaneously interrupted. For this reason, a current corresponding to the induced electromotive voltage generated in the charging / discharging coil L1 flows into the second charging capacitor C2 through the step-up switch T5, and the energy stored in the piezo element P1 can be recovered in the second charging capacitor C2. At this time, the charging voltage of the second charging capacitor C2 rises as shown in the periods t3 to t4 in FIG.

  When the second boosted voltage Vboost2 exceeds a predetermined full charge threshold (corresponding to the predetermined threshold) Vbt2, the control IC 13 controls the boost switch T5 to be turned off at timing t4 in order to stop the charging of the second charging capacitor C2. At the same time or after that, the control IC 13 controls the discharge switch T3 to be on continuously (see the period t4 to t5 in FIG. 4). Since the discharge switch T3 is kept on, the accumulated charge in the piezo element P1 is continuously discharged through the discharge switch T3. When a predetermined discharge stop condition is satisfied, the control IC 13 controls the discharge switch T3 to be turned off. As a result, the nozzle of the fuel injection port can be closed, and the fuel injection process can be stopped. As the predetermined discharge stop condition, various conditions can be applied in consideration of the condition that the piezo element P1 is sufficiently discharged, and the description thereof is omitted.

  Here, the so-called single injection has been described. The injection control process is performed by repeating these series of control processes, but the description thereof is omitted because it is not related to the features of the present embodiment.

<Relationship between injection control process and pump drive process>
As described above, the injection control process may be executed only once in a crank angle of 180 ° CA, or may be performed once in multiple stages (for example, in the case of three times, pilot injection, main injection, after injection, for example, 5 In the case of times, pilot injection, pre-injection, main injection, after-injection, and post-injection may be performed. On the other hand, the drive process of the pump 4 shown in FIG. 3 is often performed once for every crank angle of 180 ° CA, for example, and is often less than the injection control process. Moreover, the full charge threshold Vbt1 of the first boosted voltage Vboost1 for driving the piezo injector 51 is higher than the full charge threshold Vbt2 of the second boosted voltage Vboost2 for driving the pump 4. For this reason, the energy recovered from the piezo injector 51 often exceeds the drive energy of the pump 4, and by performing various controls as described above, both the injection control process and the pump drive process can be realized with good performance.

  As described above, according to the present embodiment, the second booster circuit 15 is configured to include the coil L2, the discharge switch T3, the charging capacitor C2, the booster switch T5 for preventing backflow, and the diode D2. did. For this reason, the second boosted voltage Vboost2 for driving the pump 4 can be generated using the energy stored in the coil L2 when the piezo injector 51 is closed. The coil L2 used in the above can be used as the boosting coil L2 of the second booster circuit 15 when the charge is extracted from the piezo injector 51. Thereby, for example, compared with the case where the first booster circuit 14 is provided separately for two systems, the number of coils L1 used as a large component can be reduced.

  Since the second booster circuit 15 turns on the booster switch T5 for preventing backflow when the piezo injector 51 is closed and turns on / off the discharge switch T3 to charge the second charging capacitor C2, Capacitor C2 can be charged with good performance.

(Second Embodiment)
5 and 6 show additional explanatory views of the second embodiment. In the present embodiment, boost control at start-up will be described. FIG. 5 shows an electrical configuration of an electronic control device 102 that replaces the electronic control device 2. The electronic control device 102 shown in FIG. 5 is different from the electronic control device 2 shown in FIG. 1 in that a bypass switch Tx is connected between the node N1 and the node N3. The bypass switch Tx is configured by, for example, a P-channel type MOS transistor. The source and drain of the MOS transistor constituting the bypass switch Tx are connected between the node N1 and the node N3, and the gate of the MOS transistor is on / off controlled by the control IC 13. Since the other configuration is the same as that of the first embodiment, the description of the configuration is omitted.

<Description of operation related to boost control at start-up>
FIG. 6 schematically shows the operation at the time of starting with a timing chart. When a power switch (not shown) such as an ignition switch is turned on, a power supply voltage VB from the battery is supplied to the microcomputer 12 and the control IC 13. When the power supply voltage VB is supplied to the microcomputer 12 and the control IC 13, the microcomputer 12 transmits a boost start command signal to the control IC 13.

  When the control IC 13 receives a boost start command signal from the microcomputer 12, it first turns on the bypass switch Tx. When the bypass switch Tx is turned on, the first and second charging capacitors C1 and C2 are electrically connected in parallel.

  Then, the control IC 13 repeats the ON / OFF control of the boost switch T1, thereby charging the first and second charging capacitors C1 and C2 to the respective boost voltages Vboost1 and Vboost2 to full charge thresholds Vbt1 and Vbt2. When the boost switch T1 is turned on, the coil L1 accumulates energy, and when the boost switch T1 is turned off, the accumulated energy of the coil L1 is charged in both charging capacitors C1 and C2. When the control IC 13 repeatedly controls on / off of the boost switch T1, both the first boost voltage Vboost1 and the second boost voltage Vboost2 rise as shown in FIG.

  The control IC 13 detects the voltage between the terminals of the first and second charging capacitors C1 and C2, that is, the first boosted voltage Vboost1 and the second boosted voltage Vboost2. The full charge threshold Vbt2 of the second boosted voltage Vboost2 is lower than the full charge threshold Vbt1 of the first boosted voltage Vboost1. For this reason, when the second boosted voltage Vboost2 reaches the full charge threshold value Vbt2 of the second boosted voltage Vboost2, the control IC 13 controls the bypass switch Tx to turn off to stop the boosting control of the second boosted voltage Vboost2. .

  The control IC 13 continues the on / off control of the boost switch T1 even after the bypass switch Tx is turned off. At this time, the first boosted voltage Vboost1 can be boosted while maintaining the second boosted voltage Vboost2. When the first boosted voltage Vboost1 reaches its full charge threshold value Vbt1, the control IC 13 controls the booster switch T1 to turn off to stop the boosting control of the first boosted voltage Vboost1. As shown in FIG. 6, the booster switch T5 is held off at the start. Thereby, both the first and second charging capacitors C1 and C2 can be fully charged up to the full charge thresholds Vbt1 and Vbt2.

<Boosting operation when boosted voltage Vboost2 drops to charge request threshold Vbt2>
As described in the first embodiment, when the pump 4 is driven, the control IC 13 boosts the second boosted voltage Vboost by setting a charge request flag when the second boosted voltage Vboost2 decreases and reaches the charge request threshold Vbu2. Enable to start.

  Even in such a case, when the circuit configuration according to the present embodiment is adopted, the control IC 13 can directly control the charging of the second charging capacitor C2 by turning on the bypass switch Tx. For this reason, by using the circuit configuration of the second embodiment, the second charging capacitor C2 can be directly charged to the full charge threshold Vbt2 without charging through the coil L2 at the time of injection control as shown in the first embodiment.

<Conceptual summary of this embodiment>
As described above, according to the present embodiment, when the second booster circuit 15 starts to generate the second boosted voltage Vboost2 at start-up, the bypass switch Tx is turned on, and the second booster circuit 15 The second boosted voltage Vboost2 is boosted from the supply node N1 of the 14 boosted voltages Vboost1 to the full charge threshold Vbt2. As a result, even if the second boosted voltage Vboost2 of the second booster circuit 15 decreases, recharging can be performed up to the full charge threshold Vbt2, and the pump 4 can be driven with high reliability.

(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.

  In the first embodiment, the boost control process by the second booster circuit 15 at the time of starting the electronic control device main body 2 has not been described. However, when the circuit configuration of the first embodiment is adopted, for example, The boosting operation of the second booster circuit 15 may be performed by applying a current that does not open the piezo injector 51 to the piezo injector 51 during startup.

  In this case, for example, the charging voltage of the second charging capacitor C2 may be boosted by the control IC 13 performing on / off control while turning on / off the charging switch T2 while making the on / off cycle of the boosting switch T5 longer than normal. . The voltage boosting control method for the second charging capacitor C2 at the start is not limited to the circuit configuration shown in the first embodiment, and is similarly applied when other circuits such as a bypass switch Tx are added as in the second embodiment. it can.

  In order to drive other actuators other than the fuel injection valves such as the fuel injection valve and the pump 4 by the piezo injectors 51 to 54, the embodiment using the two charging capacitors C1 and C2 has been described. The same applies to a form in which a charging capacitor is connected.

  Various control devices may be used instead of the microcomputer 12 and the control IC 13. 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.

  As a fuel injection valve, the form which applied the piezoelectric injectors 51-54 was shown, However, A capacitive fuel injection valve is applicable. As an actuator, although the form which applied the pump 4 and the pressure-reduction valve 9 was shown, you may apply to another actuator. Even in such a case, the same effects can be obtained.

  2 and 5 illustrate the configuration for driving the piezo element P1 of the piezo injector 51 for one cylinder and the electromagnetic coil 71 for driving the pump 4, but it has been described for a plurality of cylinders. When controlling the piezo injectors 51 to 54, the first booster circuit 14 may be shared to drive all of the piezo injectors 51 to 54, and the second booster circuit 15 drives the pump 4 and the pressure reducing valve 9. It is good to share to do.

  In the above-described embodiment, for simplicity of explanation, the piezo injectors 51 to 54 for four cylinders have been described, but the same contents are executed even when control for a plurality of cylinders such as six cylinders is performed. it can. Although the various switches T1 to T8 and Tx are configured by MOS transistors, other types of transistors and the like can be used.

  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 limit the technical scope of the present invention. It is not a thing. An aspect in which a part of the above-described embodiment is omitted as long as the problem can be solved can be regarded as the embodiment. In addition, any conceivable aspect can be regarded as an embodiment as long as it does not depart from the essence of the invention specified by the words described in the claims.

  Moreover, although this invention was described based on embodiment mentioned above, it understands that this invention is not limited to the said embodiment and structure. The present invention includes various modifications and modifications within an equivalent range. In addition, various combinations and forms, as well as other combinations and forms including one element, more or less, are within the scope and spirit of the present disclosure.

  In the drawings, 2 is an electronic control unit, 4 is a fuel supply pump (actuator), 9 is a pressure reducing valve (actuator), 14 is a first booster circuit, 15 is a second booster circuit, and 51 to 54 are piezo injectors (capacitive). Fuel injection valve), P1 is a piezo element, Vboost1 is a first boost voltage, Vboost2 is a second boost voltage, T2 is a charge switch, T3 is a discharge switch, T5 is a boost switch, D2 is a diode, C1 and C2 are charge capacitors, L2 represents a coil, and Tx represents a bypass switch.

Claims (6)

An electronic control device (2) for driving a capacitive fuel injection valve and an actuator other than the fuel injection valve,
A first booster circuit (14) provided for driving the fuel injection valve and capable of supplying a first boosted voltage (Vboost1) obtained by boosting a power supply voltage;
A charge switch electrically connected to the fuel injection valve for charging the capacitive fuel injection valve through a coil (L2) with a first boosted voltage of the first booster circuit to open the fuel injection valve (T2),
A discharge switch (T3) for discharging the charge accumulated in the capacitive fuel injection valve through the coil to close the fuel injection valve;
A second booster circuit (15) provided for driving the other actuator and generating a second boosted voltage (Vboost2) higher than the power supply voltage according to the first boosted voltage of the first booster circuit;
The second booster circuit includes the coil, the discharge switch, a charging capacitor (C2) for charging the second boosted voltage, and a booster switch for preventing a backflow provided between the coil and the charging capacitor ( T5) and a diode (D2).   2. The electronic control unit according to claim 1, wherein the second booster circuit turns on a booster switch for preventing backflow when the fuel injection valve is closed, and charges the charging capacitor by turning on and off the discharge switch. 3.   3. The electronic control unit according to claim 1, wherein a full charge voltage (Vbt <b> 2) of the second boost voltage of the second boost circuit is lower than a full charge voltage (Vbt <b> 1) of the first boost voltage of the first boost circuit.   The electronic control device according to any one of claims 1 to 3, wherein the second booster circuit performs a boosting operation by applying a current to the fuel injector so that the fuel injector does not open during start-up. . A bypass switch (Tx) for outputting a first boosted voltage supply node of the first booster circuit to a second boosted voltage supply node of the second booster circuit;
When the second booster circuit starts generating the second boosted voltage at the start-up, the bypass switch is turned on, and the second booster circuit supplies the second boosted voltage from the boosted voltage supply node of the first booster circuit to a predetermined level. The electronic control device according to claim 1, wherein the voltage is boosted to a threshold value. The electronic control device according to any one of claims 1 to 5, wherein the other actuator includes a pump (4) for increasing the fuel pressure or a pressure reducing valve (9) for reducing the fuel pressure. .

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