JP6308082B2 - Injector drive device - Google Patents

Description

  The present invention relates to an injector driving device that drives an injector that injects fuel into a cylinder of an internal combustion engine.

  When this type of injector driving device drives an electromagnetic coil at high speed, for example, a boosted voltage obtained by boosting a power supply voltage (for example, battery voltage) is charged in a capacitor in advance, and this charging energy is discharged to the electromagnetic coil of the electromagnetic valve. There is a technique. This is because time is insufficient to control the drive solenoid of the solenoid valve only by applying the power supply voltage of the vehicle. Therefore, the injector driving device is configured by connecting in series a discharge switching element for discharging the boosted voltage, an electromagnetic coil of a solenoid valve, and a cylinder selection switching element (for example, Patent Documents). 1).

JP 2009-25579 A

  For example, when the amount of current consumed in the vehicle is relatively large, such as during cranking at the time of start-up, and the power supply voltage tends to decrease, it is supplied to the control unit (equivalent to an on / off control unit) of the switching element for cylinder selection The power supply voltage will drop. As a result, the control unit cannot sufficiently drive the switching element for cylinder selection, and the on-resistance of the switching element increases. When the boosted voltage is supplied to the cylinder selection switching element through the discharge switching element and the electromagnetic coil, a large current flows, so that a large electric power is applied to the switching element.

  An object of the present invention is to provide an injector driving device that can protect a switching element for cylinder selection.

According to the first aspect of the present invention, the discharge switching element supplies on / off the boosted voltage obtained by boosting the power supply voltage to the solenoid coil for driving the solenoid valve. The cylinder selection switching element is connected in series to the discharge switching element and the electromagnetic coil. The power supply voltage is supplied to the on / off control unit, and the on / off control unit controls on / off of the cylinder selection switching element. At this time, the protection unit responds to a signal generated at the input terminal of the cylinder selection switching element. The discharge switching element is turned off. Therefore, even if the on-resistance of the switching element can not be sufficiently ON-driving the switching element for power supply voltage supplied is reduced cylinder selection to the on-off control unit rises, the protection portion, of the cylinder selecting switching element When the on-resistance is higher than that during normal control and the voltage at the input terminal of the cylinder selection switching element reaches a predetermined threshold voltage, the discharge switching element is turned off, so that the current flowing through the cylinder selection switching element And the switching element for cylinder selection can be protected.
According to the third aspect of the present invention, the protection unit has a higher ON resistance of the cylinder selection switching element than during normal control, and a voltage generated at the input terminal of the cylinder selection switching element and a current flowing through the cylinder selection switching element. Since the discharge switching element is controlled to be off when the multiplication result of the multiplication unit that multiplies and reaches a predetermined power threshold, the current flowing through the cylinder selection switching element can be suppressed, and the cylinder selection switching element can be protected.

Electrical configuration diagram schematically showing a configuration example of a main part of the injector drive device according to the first embodiment 1 is an electrical configuration diagram schematically showing an overall configuration example of an injector drive device according to a first embodiment. Timing chart schematically showing an example of an operation according to the first embodiment Electrical configuration diagram schematically showing a configuration example of a main part of an injector drive device according to a second embodiment IV characteristic diagram schematically showing an example of a normal operation range according to the second embodiment Timing chart schematically showing an example of operation according to the second embodiment Electrical configuration diagram schematically showing a configuration example of a main part of an injector drive device according to a third embodiment Circuit configuration diagram schematically showing a configuration example of a determination unit according to the third embodiment The flowchart which shows roughly the determination processing content of the determination part which concerns on 3rd Embodiment.

  Hereinafter, several embodiments of the injector driving device will be described with reference to the drawings. In each embodiment, configurations that perform the same or similar operations are denoted by the same or similar reference numerals, and description thereof is omitted as necessary.

(First embodiment)
First, the electrical configuration of the injector driving device 1 will be described with reference to FIGS. 1 and 2. Here, FIG. 2 shows a configuration example for N cylinders. FIG. 1 mainly shows the internal configuration of the control IC 4 functionally in order to explain the features according to the embodiment. For the external configuration, only the configuration for one cylinder is shown for convenience.

  An injector drive device 1 shown in FIG. 1 is mounted on an ECU (Electronic (Engine) Control Unit) 2 and operates when a power supply voltage VB is supplied from a battery. Here, a specific example in which the power supply voltage VB is a 12V system is shown, but it may be a 24V system and can be changed as appropriate. The ECU 2 includes a microcomputer 3 (hereinafter referred to as a microcomputer), a control IC 4, and a drive circuit 5. The ECU 2 controls the power supply to the electromagnetic coil 6 for driving the electromagnetic valve connected to the output terminals 2 a and 2 b of the ECU 2.

  The microcomputer 3 is constituted by, for example, an internal memory (not shown) such as a CPU, RAM, and ROM, and executes a program stored in the internal memory, whereby an injection command (injection start command, injection stop) is sent to the control IC 4. Command) or a preset value set in the control IC 4 can be changed.

  The drive circuit 5 is mainly composed of a booster 7, a discharge transistor (equivalent to a switching element for discharge) 8, a constant current transistor (equivalent to a switching element for constant current) 9, and a cylinder selection transistor (equivalent to a switching element for cylinder selection) 10. The current detection resistor 11, the noise filter 12, and the unidirectional energization diodes 13 to 15 are combined.

  The step-up unit 7 is configured by combining, for example, an inductor 16, an N-channel type MOS transistor 17, a diode 18, an electrolytic capacitor 19, and resistors 20 to 21 in the illustrated form. The power supply voltage VB is boosted in response to an on / off control signal applied to the gate of the capacitor, and the electrolytic capacitor 19 is charged with the boosted voltage. More specifically, a boosting pulse is applied to the gate (control terminal) of the MOS transistor 17 from the charge control circuit 4a in the control IC 4, and the positive terminal of the electrolytic capacitor 19 is charged with the boosted voltage. The charge control circuit 4a in the control IC 4 outputs a boost pulse so that the boost voltage becomes equal to a predetermined voltage.

  This boosted voltage is input to the source (input terminal) of the discharge transistor 8. The discharge transistor 8 is composed of, for example, a P-channel MOS transistor, and is a boosted voltage input to the input terminal (source) in response to a control signal supplied from the discharge control circuit 4c of the control IC 4 to the control terminal of the discharge transistor 8. From the output terminal (drain) side to the plus-side output terminal 2a of the ECU 2.

  Diodes 13 and 14 are connected to the plus output terminal 2 a of the ECU 2. These diodes 13 and 14 are provided to prevent energization of the power supply voltage VB to the supply terminal side and the ground terminal side. The diode 13 is connected in the reverse direction between the plus output terminal 2a of the ECU 2 and the supply terminal of the power supply voltage VB. The diode 14 is connected in the reverse direction between the plus output terminal 2a of the ECU 2 and the ground terminal. The drain and source of the constant current transistor 9 are connected between the anode of the diode 13 and the supply terminal of the power supply voltage VB. The constant current transistor 9 is composed of, for example, a P-channel type MOS transistor, and an input terminal (source) in accordance with an on / off control signal given from the constant current control circuit 4b of the control IC 4 to the control terminal (gate) of the constant current transistor 9 ) Can be energized to the output terminal (drain) side.

  An electromagnetic coil 6 is connected between the plus output terminal 2 a and the minus output terminal 2 b of the ECU 2. For example, when energized, the electromagnetic coil 6 drives a solenoid (not shown) to open a solenoid valve (not shown), and when energized, drives the solenoid to close the solenoid valve.

  A diode 15 is connected in the forward direction between the minus output terminal 2b of the ECU 2 and the output node of the boosted voltage of the booster 7 (the input terminal of the discharge transistor 8). The diode 15 is configured to feedback-charge the energy stored in the electromagnetic coil 6 to the electrolytic capacitor 19 of the booster 7 when the injection command is turned off.

  Between the minus output terminal 2b of the ECU 2 and the ground terminal, the drain-source of the cylinder selection transistor 10 and the current detection resistor 11 are connected in series. The cylinder selection transistor 10 is composed of, for example, an N-channel type MOS transistor, and is turned on / off according to an on / off control signal supplied from the cylinder selection control circuit 4d of the control IC 4 to the control terminal (gate) of the cylinder selection transistor 10. Thereby, a cylinder required for injection control is selected. A signal (voltage) at the input terminal (drain) of the cylinder selection transistor 10 is input to the control IC 4. In addition, the noise filter 12 is configured by a low-pass filter in which resistors 22 and 23 and a capacitor 24 are combined, for example.

  The drive circuit 5 for one cylinder has been described with reference to FIG. 1. In the case of N (≧ 2) cylinders, the ECU 2 includes N (for example, 6) cylinders as shown in FIG. The injector electromagnetic coil 6 (6a to 6f) is connected, and in the ECU 2, a drive circuit 5 for driving the injector electromagnetic coil 6 (6a to 6f) for N cylinders is configured. . In FIG. 2, components 2 a, 2 b, 6, and 10 provided for N cylinders are indicated by subscripts a to f, respectively, and components 8, 9, 11, provided for N / 2 cylinders are shown. 13 and 14 are indicated by subscripts a to c. As shown in FIG. 2, for example, N cylinder selection transistors 10 (10a to 10f) are connected in parallel. Further, N / 2 discharge transistors 8 (8a to 8c) are connected in parallel, and N / 2 constant current transistors 9 (9a to 9c) are also connected in parallel. Other peripheral circuits (diodes 13 (13a to 13c), 14 (14a to 14c)) are also configured. Each of the discharge transistors 8 (8a to 8c) and the constant current transistors 9 (9a to 9c) is composed of a pair of cylinders as one group. Thereby, the drive circuit 5 of the solenoid valve for N cylinders can be comprised, and the solenoid valve for N cylinders can be driven.

  The current detection resistors 11 (11a to 11c) are connected in series for each pair of cylinder selection transistors 10 (10a and 10d, 10b and 10e, 10c and 10f), and the cylinder selection transistors 10 (10a and 10c) are connected in series. 10d, 10b and 10e, 10c and 10f) are detected. The detection voltage of the resistor 11 (11a to 11c) is input to the control IC 4 via a noise filter 12 (partially not shown) provided for each resistor.

  Hereinafter, the internal configuration of the control IC 4 will be described with reference to FIG. Although FIG. 1 shows the configuration for one cylinder, the corresponding components perform the same control in the configuration for N cylinders shown in FIG.

  The control IC 4 is mainly composed of hardware including a logic circuit, for example. The control IC 4 includes the above-described charge control circuit 4a, constant current control circuit 4b, discharge control circuit 4c, cylinder selection control circuit 4d (equivalent to an on / off control unit), an amplifier circuit 25, a register (equivalent to a storage unit) 26, D / An A converter 27, comparators 28 and 29, a resistance voltage dividing circuit 30, and a comparison circuit 31 are provided. A set value is given to the register 26 from the microcomputer 3, and the register 26 holds this set value. The D / A converter 27 D / A converts the set value held in the register 26 and outputs it to the comparator 28 as an analog threshold value. The comparator 28 compares the output signal of the D / A converter 27 with the signal (voltage) of the input terminal (drain) of the cylinder selection transistor 10 and outputs the comparison result to the comparator 29.

  A resistance voltage dividing circuit 30 is configured at the output of the comparator 28. The resistance voltage dividing circuit 30 is configured by connecting resistors 32 and 33 in series between a power supply terminal and a ground terminal. The resistance voltage dividing circuit 30 is supplied with the internal power supply voltage Vcc (for example, 5 V) of the control IC 4, and generates a divided voltage of the voltage Vcc in a single configuration.

  In the comparator 28, for example, the transistor 28a constituting the output stage has an open collector output configuration, and the output signal (voltage) of the D / A converter 27 is more than the signal (voltage) of the input terminal (drain) of the cylinder selection transistor. When the voltage is high, the output transistor 28 a is turned on to short-circuit the resistor 32 on the ground side of the resistance voltage dividing circuit 30 and output 0 V to the inverting input terminal of the comparator 29. On the contrary, when the output signal (voltage) of the D / A converter 27 is lower than the signal (voltage) of the input terminal (drain) of the cylinder selection transistor 10, the output voltage by the resistance voltage dividing circuit 30 is turned off. The divided voltage is output to the inverting input terminal of the comparator 29.

  On the other hand, the amplifier circuit 25 amplifies the detection voltage by the resistor 11 input through the noise filter 12 and outputs the amplified voltage to the non-inverting input terminal of the comparator 29. The comparator 29 compares the amplified signal (amplified voltage) of the amplifier circuit 25 with 0V or the divided voltage by the resistance voltage dividing circuit 30, and outputs the comparison result to the discharge control circuit 4c. This comparison result is also output to the constant current control circuit 4b.

  The amplified signal (amplified voltage) of the amplifier circuit 25 is also output to the comparison circuit 31. The comparison circuit 31 compares a threshold voltage (corresponding to the current upper limit value Ip2 and the current lower limit value Ip1) provided in advance for constant current control with the amplified voltage of the amplifier circuit 25, and compares the comparison result with constant current control. Output to circuit 4b. The constant current control circuit 4b is configured to be able to turn on and off the constant current transistor 9, and controls the injector current to be in a constant current range Iw (current upper limit value Ip2, current lower limit value Ip1). The current control unit 34 includes an amplifier circuit 25, a resistance voltage dividing circuit 30, comparators 28 and 29, a register 26, a D / A converter 27, a cylinder selection control circuit 4d, a discharge control circuit 4c, a constant current control circuit 4b, and The comparison circuit 31 is used to form a protection unit.

  Hereinafter, the operation of the present embodiment will be described with reference to the timing chart shown in FIG. First, normal operation will be described. When the power supply voltage VB is supplied, the microcomputer 3 holds the set value in the register 26 in the control IC 4. The register 26 holds a set value corresponding to the limit value (upper limit value) of the drain voltage of the cylinder selection transistor 10. Since the D / A converter 27 D / A converts the set value and outputs it to the comparator 28, the comparator 28 compares the threshold voltage Vdt corresponding to this set value with the drain voltage Vv of the cylinder selection transistor 10. In the initial state, since the drain voltage Vv of the cylinder selection transistor 10 is lower than the threshold voltage Vdt, the comparator 28 turns off the output transistor 28a. On the other hand, when the power supply voltage VB is supplied, the charging control circuit 4a in the control IC 4 controls the charging of the electrolytic capacitor 19 of the boosting unit 7 by driving the transistor 17 constituting the boosting unit 7 on and off. The boosted voltage is stored in 19. At this time, since the discharge transistor 8 is controlled to be off, the boosted voltage charged in the electrolytic capacitor 19 is held.

  Thereafter, an injection signal (injection start command, injection stop command) corresponding to a certain cylinder of the microcomputer 3 is output to the control IC 4. When an injection start command for a cylinder is given, the control IC 4 of the ECU 2 turns on the cylinder selection control circuit 4d, turns on the cylinder selection control signal, turns on the discharge control signal, and further controls the constant current control circuit 4b with a constant current. The control signal is turned on (see timing t1 in FIG. 3). As a result, a current based on the boosted voltage of the booster 7 flows through the discharge transistor 8, the electromagnetic coil 6, and the cylinder selection transistor 10. Since the boosted voltage of the boosting unit 7 is higher than the power supply voltage VB, the current does not normally flow to the constant current transistor 9 due to the backflow preventing action of the diode 13.

  The control IC 4 detects the injector current by detecting the terminal voltage of the resistor 11 by the amplifier circuit 25 via the noise filter 12. When the injector current reaches a certain target peak current, a voltage corresponding to the target peak current is applied to the non-inverting input terminal of the comparator 29. At this time, the comparator 29 outputs “H”. As a result, the discharge control circuit 4c turns off the discharge control signal, and the constant current control circuit 4b turns off the constant current control signal (see timing t2 in FIG. 3). As a result, the injector current decreases. After that, the constant current control circuit 4b changes the injector current to the predetermined range Iw1 between the lower limit value Ip1 and the upper limit value Ip2 according to the comparison result of the comparison circuit 31 that compares the amplified voltage of the amplifier circuit 25 with the predetermined threshold value (see above). (See timings t3 to t4 in FIG. 3). Thereafter, when the microcomputer 3 outputs an injection stop command to the control IC 4 of the ECU 2, the cylinder selection control circuit 4d in the control IC 4 controls to turn off the cylinder selection control signal (see timing t4 in FIG. 3). As a result, the drain voltage of the cylinder selection transistor 10 rises sharply, but the current can be feedback-charged to the electrolytic capacitor 19 of the booster 7 through the diode 15 so that the booster 7 can absorb energy.

  The normal control is performed in this way, but it is assumed that the power supply voltage VB decreases according to some influence. As a cause of this, there is a case where the amount of current consumption in the vehicle is relatively large, such as cranking at the time of starting, and the power supply voltage VB tends to decrease. Even in such a case, when the microcomputer 3 outputs an injection start command for a certain cylinder to the ECU 2, the cylinder selection control circuit 4d turns on the cylinder selection control signal, the discharge control circuit 4c turns on the discharge control signal, and a constant current. The control circuit 4b turns on the constant current control signal (see timing t5 in FIG. 3).

  When the power supply voltage VB is lower than usual, the supply voltage to each circuit such as the cylinder selection control circuit 4d, the discharge control circuit 4c, and the constant current control circuit 4b is also reduced. At this time, the booster 7 can output the boosted voltage if the electrolytic capacitor 19 is charged with the boosted voltage. Further, since the boost voltage is applied to the source of the discharge transistor 8 in the discharge control circuit 4c, when the discharge control circuit 4c controls the discharge transistor 8 on, the gate-source voltage of the discharge transistor 8 is sufficiently high. can do. Therefore, even if the power supply voltage VB decreases, the discharge transistor 8 can be sufficiently turned on, and the on-resistance of the discharge transistor 8 can be kept low.

  However, if the power supply voltage VB decreases, the cylinder selection control circuit 4d may not be able to sufficiently drive the gate of the cylinder selection transistor 10. In this case, the cylinder selection transistor 10 may not be sufficiently turned on. As a result, the on-resistance between the drain and source of the cylinder selection transistor 10 is increased. When the on-resistance between the drain and the source of the cylinder selection transistor 10 becomes high, the drain voltage Vv of the cylinder selection transistor 10 becomes abnormally high even if the injector current does not reach the target peak current Ip. In such a case, the drain voltage Vv of the cylinder selection transistor 10 reaches the threshold voltage Vdt before the injector current reaches the target peak current Ip (see timing t6 in FIG. 3).

  As a result, the comparator 28 turns on the output transistor 28a, short-circuits the resistor 32 of the resistance voltage dividing circuit 30 for a moment, reduces the input voltage of the inverting input terminal of the comparator 29 to 0 V, for example, and the comparator 29 receives both inputs. “H” is output as the terminal comparison result. At this time, the discharge control circuit 4c turns off the discharge control signal for a moment, and the constant current control circuit 4b turns off the constant current control signal for a moment (see timing t6 in FIG. 3). Thereby, the discharge through the discharge transistor 8 and the constant current transistor 9 is stopped. In this case, the injector current decreases without reaching the target peak current Ip (see timings t6 to t7 in FIG. 3).

  After the predetermined time has elapsed, the control IC 4 keeps the constant current control circuit 4b on-controlling the constant current control signal while the cylinder selection control circuit 4d controls the cylinder selection control signal on (timing t7 in FIG. 3). See t8). Since the constant current control circuit 4b controls the constant current transistor 9 to be on, the current can be continuously supplied to the electromagnetic coil 6. As a result, while the control IC 4 of the ECU 2 receives the injection start command from the microcomputer 3, it is possible to continue the current flow through the electromagnetic coil 6 as much as possible, and during this time, the electromagnetic valve can be opened as much as possible. Therefore, when the injection start command is given in this way, even if the voltage drop state of the power supply voltage VB continues during the cranking time, it is possible to prevent the startability from being deteriorated as much as possible.

  For example, when the amount of current consumption in the vehicle decreases, the power supply voltage VB also returns. In such a case, the cylinder selection control circuit 4d can sufficiently drive the gate of the cylinder selection transistor 10, and can sufficiently increase the gate-source voltage of the cylinder selection transistor 10. As a result, similarly to the above-described normal operation, even when the discharge control circuit 4c controls the injector transistor to the target peak current Ip by turning on the discharge transistor 8 during the discharge of the boosted voltage of the booster 7, the cylinder The on-resistance of the selection transistor 10 can be kept sufficiently low. For this reason, the drain voltage Vv of the cylinder selection transistor 10 does not reach the threshold voltage Vdt. Thereby, when the power supply voltage VB is restored, the control operation can be automatically restored. Thus, if the power supply voltage VB is restored separately, the control can be automatically restored (see timing t9 and thereafter in FIG. 3). In this case, it is not necessary to separately provide an abnormality detection means.

  As described above, according to the present embodiment, since the power supply voltage VB supplied to the cylinder selection control circuit 4d is lowered, the cylinder selection transistor 10 cannot be sufficiently turned on, and the on-resistance of the cylinder selection transistor 10 is reduced. Even if the current rises, the current control unit 34 serving as a protection unit controls the discharge transistor 8 to be turned off according to the drain voltage Vv of the cylinder selection transistor 10. For this reason, the electric current which flows into the cylinder selection transistor 10 can be suppressed, and the cylinder selection transistor 10 can be protected.

  Further, even after the discharge control circuit 4c controls the discharge transistor 8 to be turned off and the constant current control circuit 4b once controls the constant current transistor 9 to be turned off in response to the decrease in the drain voltage Vv of the cylinder selection transistor 10, Since the constant current control circuit 4b continues to control the constant current transistor 9 to be on, deterioration of the engine startability can be prevented.

  The set value of the register 26 can be arbitrarily set from the external microcomputer 3. For this reason, even if the design of cylinder selection transistor 10, discharge transistor 8, constant current transistor 9 in ECU 2, various characteristics, and / or resistance values of various resistors 11, etc., are changed, the design change status remains. In addition, the set value of the register 26 can be changed, and the degree of freedom in design can be improved.

  When the power supply voltage VB is low, the power supply voltage supplied to the external microcomputer 3 may be low. In such a case, it is assumed that the control IC 4 of the ECU 2 cannot receive the injection command (injection start command, injection stop command) from the microcomputer 3. If such a thing is assumed, it is desirable to comprise the structure in control IC4 with the hardware which enabled control IC4 to operate independently rather than the structure which operate | moves with software.

(Second Embodiment)
4 to 6 are explanatory diagrams of the second embodiment. In the second embodiment, a current control unit 134 that replaces the current control unit 34 includes a multiplier (equivalent to a multiplication unit) 35 that multiplies the drain voltage Vv of the cylinder selection transistor 10 and the current flowing through the cylinder selection transistor 10. A mode in which the discharge transistor 8 is turned off in accordance with the multiplication result by the multiplication unit 35 is shown.

As shown in FIG. 4, the configuration of the current control unit 134 serving as a protection unit is changed from that of the current control unit 34. In addition to the configuration shown in FIG. A device 35 is provided in front of the comparator 28. The voltage buffer 36 has a configuration of high input and low output impedance, and outputs the drain voltage Vv of the cylinder selection transistor 10 to the multiplier 35. The multiplier 35, the output voltage Vv of the voltage buffer 36, multiplies the detected voltage V _I according to the detected current of the resistor 11, and outputs to the inverting input terminal of the comparator 28. The comparator 28 compares the input multiplication result of the multiplier 35 with the output voltage of the D / A converter 27 and opens / shorts the resistor 32 of the resistance voltage dividing circuit 30 according to the comparison result.

  FIG. 5 schematically shows a safe operating area (SOA: Safe Operating Area) of the cylinder selection transistor 10. The horizontal axis indicates the voltage applied between the drain and the source of the cylinder selection transistor 10, and the vertical axis indicates the drain current Id of the cylinder selection transistor 10. The cylinder selection transistor 10 is desirably operated so as to satisfy the SOA rating. Basically, the upper limit value of the drain-source voltage Vds of the cylinder selection transistor 10 is set to the predetermined voltage Vlim, and the drain current Id It is required to operate within a predetermined power range where the upper limit value is a predetermined current Ilim. Since no voltage exceeding that defined by the maximum on-resistance Ron of the cylinder selection transistor 10 is generated, when the drain-source voltage Vds of the cylinder selection transistor 10 is lower than a certain intermediate voltage Vm, the drain current Id is The upper limit value is set in proportion to the source-to-source voltage Vds.

  In the present embodiment, the specifications of the cylinder selection transistor 10 and other various circuit constants (for example, the filter constant of the noise filter 12, the gain of the multiplier 35, etc.) are set so that the cylinder selection transistor 10 operates within a range that satisfies the SOA rating. The gain of the voltage buffer 36, the gain of the amplifier circuit 25, the set value of the register 26, etc.) are determined. When the multiplication result of the multiplier 35 reaches a predetermined power threshold value Pdt, the discharge transistor 8 is controlled to be off. The operation is performed in a range satisfying the SOA rating.

  When the configuration shown in FIG. 4 is adopted, when the multiplication result of the multiplier 35 reaches a predetermined power threshold value Pdt, the comparator 28 shorts the resistor 32 of the resistance voltage dividing circuit 30, thereby causing the discharge control circuit 4 c and the constant current control. The circuit 4b forcibly turns off the discharge transistor 8 and the constant current transistor 9.

  As shown in a schematic timing chart in FIG. 6, when the power supply voltage VB is in the normal voltage range, even if the boosted voltage of the booster 7 is energized to the electromagnetic coil 6 and the cylinder selection transistor 10 through the discharge transistor 8. Since the on-resistance of the cylinder selection transistor 10 is low, the multiplication result of the multiplier 35 can continue normal operation without reaching the power threshold value Pdt (see timings t1 to t4 in FIG. 6). However, when the power supply voltage VB decreases from the normal voltage range, if the cylinder selection control circuit 4d cannot sufficiently drive the cylinder selection transistor 10, the on-resistance of the cylinder selection transistor 10 increases, and the multiplication result of the multiplier 35 is The power threshold value Pdt may be reached (see timings t5 to t6a in FIG. 6). In this case, the discharge control circuit 4c controls the discharge transistor 8 to be turned off, and the constant current control circuit 4b controls the constant current transistor 9 to be turned off. Then, the drain voltage Vv of the cylinder selection transistor 10 decreases, the current flowing through the cylinder selection transistor 10 can be suppressed, and the cylinder selection transistor 10 can be protected. Since the subsequent operation is the same as that of the above-described embodiment, the description thereof is omitted (see timing t7 and thereafter in FIG. 6). The configuration of this embodiment also provides substantially the same operational effects as the previous embodiment.

(Third embodiment)
7 to 9 are explanatory views of the third embodiment. The third embodiment includes a determination unit 37 that determines whether the relationship between the drain-source voltage Vds of the cylinder selection transistor 10 and the drain current Id is within the normal operating range. Accordingly, a mode in which the cylinder selection transistor 10 is controlled to be off is shown.

As shown in FIG. 7, the control IC 4 includes a determination unit 37 that replaces the comparator 28 of the first embodiment in a current control unit 234 that replaces the current control unit 34. The determination unit 37 is input drain voltage Vv of the cylinder selection transistor 10, and the output voltage of the amplifier circuit 25 is inputted as a detection voltage V _I. Determining unit 37, according to the set value given from the voltages Vv and V _I and the microcomputer 3, the resistor 32 of the resistance voltage dividing circuit 30 to open /. FIG. 8 shows a configuration example when the determination unit 37 is configured by hardware, and FIG. 9 shows a flow using a flowchart for easy understanding of the processing of the determination unit 37. The determination unit 37 includes comparators 38 to 40, a multiplier circuit 41, an adder circuit 42, a gate circuit 43, and a transistor 44.

“A” and “b” shown in FIG. 8 and FIG. 9 are set values used to express the safe operation area (corresponding to the normal operation area) shown in FIG. Setting values stored in the register 26 (not shown in FIG. 7) are shown. Thereby, the microcomputer 3 can arbitrarily set the safe operation area. As shown in FIG. 5, these “a” and “b” are, if the maximum voltage that takes the current upper limit value Ilim is V ₀ and the maximum current that takes the voltage upper limit value Vlim is I ₀ ,

のように表すことができる。

It can be expressed as

As shown in FIG. 8, the determination unit 37 compares the threshold voltage V1 set in advance in proportion to the upper limit value Vlim of the voltage in the safe operation region by the comparator 38 and the drain voltage Vv, and determines the drain / source. It is determined whether or not the inter-voltage Vds is equal to or lower than the upper limit value Vlim (NO in S1 of FIG. 9). The determination unit 37 compares the preset threshold voltage in proportion corresponding to the upper limit value Ilim of the current safe operating region V2 by the comparator 39 and the voltage V _I, the drain current Id is equal to or less than the upper limit value Ilim Whether or not (NO in S2 of FIG. 9). Further, the determination unit 37 multiplies the set value a and the drain voltage Vv by using the multiplier circuit 41, further adds the multiplication result of the multiplier circuit 41 and the set value b by the adder circuit 42, and further adds by the comparator 40. comparing the addition result of the circuit 42 and the voltage V _I. Thereby, the determination unit 37 determines whether or not the drain current Id is equal to or less than a · Vds + b (NO in S3 of FIG. 9). The determination condition indicating whether or not the drain current Id is equal to or less than a · Vds + b represents the characteristic A1 in which the limit value is inclined near the voltage upper limit value Vlim and the current upper limit value Ilim in the Id−Vds characteristic shown in FIG. Is.

  The gate circuit 43 is configured by, for example, an OR gate, and determines whether or not these determination results are satisfied. When any determination result is YES (YES in S1 to S3), the output transistor 44 is turned on. As a result, the resistor 32 of the resistance voltage dividing circuit 30 is short-circuited to reduce the threshold voltage of the comparator 29 to zero. As a result, the comparator 29 outputs “H”, the discharge control circuit 4c forcibly controls the discharge transistor 8 to be turned off, and the constant current control circuit 4b forcibly controls the constant current transistor 9 to be turned off. Thereby, the determination unit 37 can determine whether or not the cylinder selection transistor 10 is operating within the safe operation region shown in FIG. 5, and the discharge transistor 8 and the constant current transistor 9 are turned on at a timing deviating from the safe operation region. Can be controlled off.

  In the present embodiment, the safe operation region is set as the normal operation range itself. However, the safe operation region of the cylinder selection transistor 10 may be set as the normal operation range in anticipation of a margin.

(Other embodiments)
The present invention is not limited to the above-described embodiment. For example, the following modifications or expansions are possible.
At the timing when the drain voltage Vv of the cylinder selection transistor 10 reaches the threshold voltage Vdt, the discharge control circuit 4c controls the discharge transistor 8 to be turned off, and the constant current control circuit 4b controls the constant current transistor 9 to be turned off for a moment. Although the constant current transistor 9 is continuously turned on after the predetermined time has elapsed, the constant current control circuit 4b may continue to control the constant current transistor 9 to be turned off even after the predetermined time has elapsed.

The configurations of the first embodiment and the second embodiment may be used together, and the condition that the drain voltage Vv of the cylinder selection transistor 10 is less than the threshold voltage Vdt and the multiplication result of the multiplier 35 is less than the power threshold Pdt. Both of the following conditions may be adopted.
In the first to third embodiments, the processing contents of the control IC 4 are configured by hardware. However, the processing may be realized by executing software, for example. Further, the processing content of FIG. 9 described in the third embodiment may be realized by executing software.

  Although an embodiment in which an N-channel MOS transistor is used as the cylinder selection transistor 10 is shown, the present invention is not limited to this, and various transistors and switching elements can be applied. Although a mode in which a P-channel MOS transistor is used as the discharge transistor 8 and the constant current transistor 9 is shown, the present invention is not limited to this, and various transistors and switching elements can be applied.

  The configurations of the embodiments can be applied in combination as appropriate. In addition, the code | symbol with the parenthesis attached | subjected to the claim attaches | subjects the code | symbol corresponding to the component of this-application specification, and gives an example of the component. Therefore, the invention according to the present application is not limited to the elements indicated by the reference numerals attached to the constituent elements of the claims, and can be variously expanded in terms of the claims or the equivalents thereof.

  In the drawings, 8, 8a to 8c are discharge transistors (discharge switching elements), 9, 9a to 9c are constant current transistors (constant current switching elements), and 10, 10a to 10f are cylinder selection transistors (cylinder selection switching elements). , 26 are registers (storage units), 34, 134, and 234 are current control units (protection units), 35 is a multiplier (multiplication unit), and 37 is a determination unit.

Claims (10)

A discharge switching element (8, 8a to 8c) for turning on / off the boosted voltage obtained by boosting the power supply voltage to the solenoid coil for driving the solenoid valve;
Cylinder selection switching elements (10, 10a to 10f) which are connected in series to the discharge switching element and the electromagnetic coil and an input terminal and are on / off controlled by an on / off control unit to which the power supply voltage is supplied;
Protection for turning off the discharge switching element when the ON resistance of the cylinder selection switching element becomes higher than that during normal control and the voltage at the input terminal of the cylinder selection switching element reaches a predetermined threshold voltage. Unit (34 , 2 34). The protection unit (34) is configured to perform the operation when the voltage of the input terminal of the cylinder selection switching element reaches or exceeds the predetermined threshold voltage before the current flowing through the electromagnetic coil reaches a target peak current. The injector driving device according to claim 1, wherein the discharge switching element is turned off. A discharge switching element (8, 8a to 8c) for turning on / off the boosted voltage obtained by boosting the power supply voltage to the solenoid coil for driving the solenoid valve;
Cylinder selection switching elements (10, 10a to 10f) which are connected in series to the discharge switching element and the electromagnetic coil and an input terminal and are on / off controlled by an on / off control unit to which the power supply voltage is supplied;
A protection unit (134) for turning off the discharge switching element in accordance with a signal generated at an input terminal of the cylinder selection switching element;
The protection unit (134) includes a multiplication unit (35) for multiplying a voltage generated at an input terminal of the cylinder selection switching element by a current flowing through the cylinder selection switching element, and turning on the cylinder selection switching element. resistance becomes higher than the normal control, the multiplication unit according to the multiplication result Louis Njekuta drive to off control of the discharge switching element upon reaching a predetermined power threshold. The protection unit (134) turns off the discharge switching element when a multiplication result by the multiplication unit reaches a predetermined power threshold or more before a current flowing through the electromagnetic coil reaches a target peak current. Item 4. The injector driving device according to Item 3. It said protective unit (234) includes a determination unit (37) whether the current flowing in voltage and the cylinder selecting switching element of the input terminals of the cylinder selecting switching element is in the normal operating range The injector drive device according to claim 1, wherein the discharge switching element is turned off according to a determination result of the determination unit. A constant current switching element (9, 9a to 9c) for supplying a constant current to the electromagnetic coil after the boosted voltage is discharged by the discharge switching element;
The protective portion, the discharge switching element when you off control, the injector driving apparatus according to any one of claims 1 to 5, on control of the constant current switching device. When the protection unit controls the discharge switching element to be turned off in response to a signal generated at the input terminal of the cylinder selection switching element, a signal generated at the input terminal and a predetermined threshold corresponding to the signal are set. Compared to off control,
The injector driving device according to claim 1, further comprising a storage unit (26) that allows the threshold value to be arbitrarily set. When the protection unit (134) controls the discharge switching element to be turned off in accordance with the multiplication result of the multiplication unit, the multiplication result of the multiplication unit is compared with a predetermined threshold corresponding to the result. To control off,
The injector driving device according to claim 3 , further comprising a storage unit (26) that allows the threshold to be arbitrarily set. The injector driving device according to claim 5 , wherein the normal operation range can be arbitrarily set. The protection section, an injector driving apparatus according to any one of claim 1 to 9, characterized in that it is constituted by hardware.

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