JP2015055233A - Injector drive unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an injector drive unit which is hardly influenced by a variation of an element value of a constituent part for driving a transistor even if a discharge switch is constituted by using the PMOS transistor, and can quickly transit an energization current of an electromagnetic coil of an injector to constant current control from a peak current.SOLUTION: A drive control circuit 12 firstly turns off a MOS transistor 25m of a cylinder selection switch 16 at a downstream side at timing at which a peak current is detected. After that, the drive control circuit 12 turns off a pre-transistor 21nn, and when detecting that a detection voltage Vdeth of a resister RH reaches a re-ON threshold Vton, controls the MOS transistor 25m of the cylinder selection switch 16 so as to be turned on once again.

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.

  A fuel injection control device that controls fuel injection for each cylinder of an internal combustion engine includes an injector driving device for driving an electromagnetic coil. An electromagnetic coil of this injector is provided for each cylinder. When an injection command signal is input from an ECU (Electronic Control Unit), the injector driving device applies a boosted voltage to the electromagnetic coil of the injector. When a boosted voltage is applied to the electromagnetic coil, a peak current flows. After the peak current is applied, adjustment control is performed to a constant current that is lower than the peak current.

  A discharge switch is provided to energize this peak current. When the discharge switch has a circuit configuration using NMOS transistors, noise increases and the number of parts in the circuit configuration also increases. Therefore, noise is reduced by using a P-channel type MOS transistor (PMOS transistor) for the discharge switch. In addition, the technique of patent document 1 is mentioned as technical literature relevant to this application.

JP 2007-116804 A

  When the discharge switch is configured using a PMOS transistor, the gate voltage needs to be controlled to a high level near the boosted voltage quickly when the switch is off, so the pre-transistor is connected to the gate of the PMOS transistor. However, in this case, the off control time of the PMOS transistor also requires a considerable time, and further, for example, a variation of about ± 30% occurs when the variation of the gate voltage control circuit is taken into consideration.

  Then, since it affects the peak current amount, the injection amount is affected. In order to solve this problem, there are methods such as trimming error adjustment of electronic parts and adding a capacitor to the control terminal of the pre-transistor. However, the former increases the number of manufacturing processes, and the latter increases the number of parts. It is not preferable.

  An object of the present invention is to provide a current flowing through an electromagnetic coil of an injector as much as possible without being affected by variations in element values of components for driving the discharge switch even when the discharge switch is configured using a PMOS transistor. It is an object to provide an injector driving device that can quickly shift from peak current to constant current control.

  According to the first aspect of the invention, the control circuit turns off the cylinder selection switch when the detection value of the second detection circuit reaches the first predetermined value indicating the peak current, and thereafter, the pre-transistor of the discharge switch is turned on. Control off. The cylinder selection switch is a switch connected in series to an electromagnetic coil provided for each cylinder. When the first detection value corresponding to the peak current is detected, the cylinder selection switch is turned off, and then the discharge switch is pre-set. The transistor is turned off.

  The detection value of the first detection circuit gradually decreases under the influence of the electromagnetic coil of the injector. Here, when the detection value of the first detection circuit reaches the second predetermined value, the control circuit turns on the cylinder selection switch again and shifts to constant current control. Then, the control circuit can perform constant current control on the electromagnetic coil of the injector.

  That is, since the control circuit first controls the cylinder selection switch to turn off when the detection value of the second detection circuit reaches the first predetermined value indicating the peak current, the energization-off transition time of the electromagnetic coil of the injector is extreme. For example, it becomes extremely smaller than turning off the discharge switch first. Moreover, the variation is extremely small.

  As a result, even when the discharge switch is configured using a PMOS transistor, it is not affected as much as possible by the component value variation of the component for driving the transistor, and the control processing of the electromagnetic coil can be performed quickly. It becomes possible to shift to constant current control.

  According to the second aspect of the present invention, when the detection value of the second detection circuit reaches the third predetermined value, the cylinder selection switch is turned on again to shift to constant current control. The same effects as the invention are achieved. Further, for example, it is possible to shift to constant current control more quickly than the invention according to claim 1.

1 is an overall configuration diagram of a fuel injection control device according to a first embodiment of the present invention. Timing chart schematically showing the flow of control Flow chart schematically showing the flow of control (part 1) Flow chart schematically showing the flow of control (part 2) Timing chart schematically showing the flow of control according to the second embodiment of the present invention (corresponding to FIG. 2) Flow chart schematically showing control flow (corresponding to FIG. 3)

  Hereinafter, some embodiments of the present invention will be described with reference to the drawings. The same or similar configurations between the embodiments are denoted by the same or similar reference numerals in the second and subsequent embodiments, only the main parts are described, and the same parts are not described.

(First embodiment)
FIG. 1 is an overall configuration diagram of the fuel injection control device. The fuel injection device includes an electronic control unit 10 (hereinafter referred to as ECU: Electronic Control Unit) that controls the engine (internal combustion engine), and each cylinder of the engine (six cylinders in this embodiment) in accordance with an injection command or an injection stop command from the ECU 10. And an injector driving device 11 for driving the injectors 1 to 6.

  The injection signals IJt1 to IJt6 are binary signals having an H level indicating a fuel injection command and an L level indicating an injection stop command, and are input from the ECU 10 to the input terminals Ta1 to Ta6 of the injector driving device 11 through an injection signal line. Has been.

  The response signals IJf1 to IJf3 become L level when the drive current conduction level of the injectors 1 to 6 is equal to or higher than a predetermined high threshold level (for example, about 4A) in normal times, and then the drive current conduction level is predetermined. Is a signal that becomes H level again when it reaches the low threshold level, and is output to the ECU 10 from the output terminals Ta7 to Ta9.

  The injectors 1 to 6 are electromagnetic types provided with solenoids L1 to L6, respectively, and open and close according to energization and disconnection of the solenoids L1 to L6. The solenoids L1 to L6 are connected between the high-side output terminals Tb1 to Tb6 and the low-side output terminals Tc1 to Tc6, respectively. The injectors 1 to 6 of each cylinder are divided into two control groups (for example, injectors 1 and 4, injectors 2 and 5, and injectors 3 and 6).

  The high-side output terminals Tb1 and Tb4, the output terminals Tb2 and Tb5, and the output terminals Tb3 and Tb6 belonging to the same group are connected in the injector driving device 11, respectively. Further, one output terminal Ta7 to Ta9 of response signals IJf1 to IJf3 is provided for each group.

  The injector drive device 11 includes a drive control circuit 12 formed as a monolithic IC, a boost power supply unit 13 that boosts the battery voltage VB that is input between the power supply terminals Td1 and Td2, and between the boost power supply unit 13 and the output terminals Tb1 to Tb6. The discharge switch 14 provided for each group, the constant current control switch 15 provided for each group that outputs a constant current to maintain the valve open state, and between the output terminals Tc1 to Tc6 and the ground. And a cylinder selection switch 16. A drive circuit (drive means) is configured including the boost power supply unit 13, the discharge switch 14, the constant current control switch 15, and the cylinder selection switch 16.

  The step-up power supply unit 13 includes step-up coils 17a and 17b, N-channel type MOS transistors 18a and 18b, diodes 19a and 19b, and capacitors 20a and 20b, and constitutes a duplexed DC / DC converter. In the boost power supply unit 13, boost coils 17a and 17b, transistors 18a and 18b, and diodes 19a and 19b are connected in parallel. In the boost power supply unit 13, capacitors 20a and 20b are connected in parallel. The step-up power supply unit 13 includes a resistor RH for detecting charging and discharging current. This resistor RH is connected in series to capacitors 20a and 20b connected in parallel, for example, and is provided for detecting the charged state of the capacitors 20a and 20b. The resistor RH may have a high resistance value and may be connected in parallel to these capacitors 20a and 20b, as long as the charged state and discharged state of the capacitors 20a and 20b can be detected.

  A common boost pulse is applied from the drive control circuit 12 to the control terminals of the MOS transistors 18a and 18b, and a boost voltage is generated at the cathodes of the diodes 19a and 19b and the positive terminals of the capacitors 20a and 20b connected in common. The drive control circuit 12 outputs a boost pulse so that the boost voltage becomes equal to a predetermined voltage.

  The discharge switch 14 includes one P-channel type main MOS transistors 21a, 21b, and 21c for each group, and transistors 21a, 21b, and 21c are arranged in front of the gate control terminals of the MOS transistors 21a, 21b, and 21c, respectively. Pre-transistors 21aa, 21bb, and 21cc, which are NPN-type bipolar transistors for driving 21c, are provided and are turned on / off by a discharge control signal.

  A resistor R1a is connected to the gate of the main MOS transistor 21a. A resistor R2a is connected between the terminal of the resistor R1a and the source of the main MOS transistor 21a. A resistor R3a is connected between the common connection node of the resistors R1a and R2a and the collector of the pre-transistor 21aa. The emitter of the pre-transistor 21aa is connected to the ground, and the base of the pre-transistor 21aa is connected to the drive control circuit 12 via the resistor R4a.

  When the drive control circuit 12 outputs an “L” level control signal to the pre-transistor 21aa, the pre-transistor 21aa is turned off. Then, current flows into the gate of the main MOS transistor 21a through the resistors R2a and R1a, and the gate-source voltage of the main MOS transistor 21a becomes low level. Then, the main MOS transistor 21a is turned off, and the boosted voltage of the boost power supply unit 13 is cut off and is not output to the terminals Tb1 and Tb4.

  Conversely, when the drive control circuit 12 outputs an “H” level control signal to the pre-transistor 21aa, a current is passed between the collector and emitter of the pre-transistor 21aa, and the charge accumulated in the gate capacitance of the main MOS transistor 21a is increased. Unplug. Then, the gate potential of the main MOS transistor 21a is lowered.

  At this time, when the source-gate voltage of the main MOS transistor 21a exceeds the threshold voltage, the boosted voltage of the boost power supply unit 13 is supplied to the terminals Tb1 and Tb4 through the source / drain of the main MOS transistor 21a. Since the drive system circuits of the main MOS transistors 21a, 21b, and 21c have the same configuration, the drive system of the main MOS transistors 21b and 21c is substituted for the subscript “a” of the components of the drive system circuit of the main MOS transistor 21a. Subscripts “b” and “c” are added to the circuit at the end of the constituent elements, respectively, and the connection relationship and operation description are omitted.

  Note that the drive system circuit of the main MOS transistor 21b includes resistors R1b to R4b and a pre-transistor 21bb. The drive system circuit for the main MOS transistor 21c includes resistors R1c to R4c and a pre-transistor 21cc.

  The constant current control switch 15 includes one MOS transistor 22a, 22b, 22c for each group. Diodes 23a, 23b, and 23c are connected in series between the MOS transistors 22a, 22b, and 22c and the terminals Tb1 and Tb4, Tb2 and Tb5, Tb3, and Tb6, respectively.

  The diodes 23a, 23b, and 23c are diodes for preventing backflow. Further, diodes 24a, 24b, and 24c are connected in reverse directions between the terminals Tb1 and Tb4, Tb2 and Tb5, Tb3 and Tb6, and the ground. These diodes 24a, 24b, and 24c are free-wheeling diodes.

  A constant current drive unit 26 is connected to the MOS transistors 22a, 22b, and 22c. The drive control circuit 12 uses the constant current drive unit 26 to output a constant current control signal so that the total current flowing through the two solenoids constituting each group becomes equal to a predetermined current value. The cylinder selection switch 16 includes MOS transistors 25a to 25f connected between the output terminals Tc1 to Tc6 and the ground, and is turned on / off by a cylinder selection control signal supplied from the drive control circuit 12. Each of these MOS transistors 25a to 25f is composed of an N channel type MOS transistor.

  The sources of the MOS transistors that drive the solenoids belonging to the same group are connected to the ground via a common current detection resistor RL. For example, when the injectors 1 and 4 belong to the same group, the sources of the MOS transistors 25a and 25d are connected in common, and the common source is connected to the ground via the current detection resistor RL.

  A trimming adjustment resistor RLb is connected to the current detection resistor RL together with the resistor RLa, and the injection amount can be initially adjusted by trimming the resistor RLb in the product shipment stage.

  The drive control circuit 12 includes a peak current detection circuit (peak determination means) 27 and a constant current detection circuit 28. The peak current detection circuit 27 detects whether or not the detection voltage Vdetl of the current detection resistor RL has reached the peak level.

  The constant current detection circuit 28 compares the detection voltage Vdetl of the current detection resistor RL with the high threshold voltage Vsmax and the low threshold voltage Vsmin for constant current control, and outputs the comparison result. The drive control circuit 12 uses the detection results of the peak current detection circuit 27 and the constant current detection circuit 28, and applies the solenoid electromagnetic coils L1 to L6 constituting each group based on the detection voltage Vdetl of the current detection resistor RL. Control the flowing current.

  In the present embodiment, the discharge switch 14 is configured using P-channel MOS transistors 21a, 21b, and 21c. Therefore, pre-transistors 21aa, 21bb, and 21cc are provided to quickly increase the gate voltage when these MOS transistors 21a, 21b, and 21c are turned off.

  However, for example, when the main MOS transistor 21a is turned off, the off control time also requires a considerable time due to the influence of the pre-transistors 21aa, 21bb, 21cc and the resistors R1a to R4a. Further, it has been found that, for example, a variation of about ± 30% occurs in consideration of variations in the drive system circuits of the main MOS transistors 21a, 21b, and 21c. Therefore, in the present embodiment, this problem is solved without using other components by devising a control method. The injection signal input to each group is the same between the groups. For this reason, in the following description, the control method when one injection signal IJt is input will be described.

  FIG. 2 shows an example of a timing chart schematically showing the signal waveform of each node when an injection command is given. FIG. 3 shows an example of a flowchart schematically showing a control method of the drive control circuit until the constant current operation of the electromagnetic coil is started after the injection signal is inputted.

  Hereinafter, the time change of the energization level of the injector will be described. The injection signal IJt is input to the drive control circuit 12 (S1 in FIG. 3). When the drive control circuit 12 receives the injection command (L → H) of the injection signal IJt, the drive control circuit 12 starts the power interruption control of the injectors 1 to 6.

  First, the drive control circuit 12 includes a MOS transistor 25m (where m = a to f: the same applies hereinafter) of the cylinder selection switch 16 and a MOS transistor 22n (where n = a, b, c) of the constant current drive unit 15. : The same applies hereinafter), and the MOS transistor 21n of the discharge switch 14 is turned on, and initial energization is performed from the constant current driving unit 15 and the boosting power source unit 13 to the electromagnetic coil of the injector (timing of “A” in FIG. 2: FIG. 3) S2).

  When the drive control circuit 12 detects that the detected voltage Vdetl of the injector current exceeds the maximum threshold voltage Vsmax for constant current control, the drive control circuit 12 stops energization to the injector through the constant current control switch 15 (constant current control switch 15 (→ OFF: “B” timing in FIG. 2).

  On the other hand, the boosting power supply unit 13 performs an initial energization process until the peak current detection circuit 27 detects the peak level of the injector current (discharge switch 14 = ON: “B” → “C” period in FIG. 2). .

  When the peak current detection circuit 27 detects the peak level (YES in S3 of FIG. 3), the drive control circuit 12 first applies an off control signal to the MOS transistor 25m of the cylinder selection switch 16, and the cylinder selection switch 16 The MOS transistor 25m is turned off (S4 in FIG. 3).

  Further, the drive control circuit 12 applies an ON control signal to the MOS transistor 22n of the constant current control switch 15 (S5 in FIG. 3), and controls OFF to the pre-transistor 22o (o = aa, bb, cc) of the discharge switch 14. A signal is applied (S6 in FIG. 3). Thus, the discharge switch 14 is controlled to be turned off (timing “C” in FIG. 2).

  Then, although the resistance RL is connected in series to the cylinder selection switch 16, the detection voltage Vdetl of the resistance RL decreases sharply and reaches zero. However, the detection voltage Vdeth of the resistor RH is prevented from being lowered because the electromagnetic coil of the injector is inductive (period TM1 from “C” to “D” in FIG. 2). The main path of the current path at this time is the resistance RL between the electromagnetic coil of the injector, the drain-source of the MOS transistor 25m of the cylinder selection transistor 16. Since the MOS transistor 25m is turned off, the drain and source of the MOS transistor 25m have high resistance, but the drain and source are also energized. For this reason, the voltage drop of the detection voltage Vdeth of the resistor RH becomes gentler than the detection voltage Vdetl of the resistor RL. A certain amount of time is required for this voltage to drop.

  When the drive control circuit 12 detects that the detection voltage Vdeth of the resistor RH has reached the re-ON threshold value Vton, the drive control circuit 12 applies the ON control signal again to the MOS transistor 25m of the cylinder selection switch 16, and The MOS transistor 25m is turned on again (S8 in FIG. 3; timing “D” in FIG. 2).

  Then, since the MOS transistor 25m of the cylinder selection switch 16 is turned on again, an energization path for the electromagnetic coil of the injector is secured. At this timing, the MOS transistor 21n of the energization switch 14 is off, and the MOS transistor 22n of the constant current control switch 15 is on. Therefore, a current is supplied from the constant current control switch 15 to the electromagnetic coil of the injector.

  Thereafter, the drive control circuit 12 shifts to constant current control (S9 in FIG. 3). In constant current control, when the drive control circuit 12 detects that the detection voltage Vdetl of the resistor RL has reached the maximum threshold voltage Vsmax for constant current control (T1: YES in FIG. 4), the MOS of the constant current control switch 15 The transistor 22n is turned off (T2 in FIG. 4). Then, the detection voltage Vdetl of the resistor RL decreases.

  Thereafter, when the drive control circuit 12 detects that the detection voltage Vdetl of the resistor RL has reached the minimum threshold voltage Vsmin for constant current control (T4 in FIG. 4: YES), the drive control circuit 12 turns on the MOS transistor 22n of the constant current control switch 15. The on-control is again performed (T5 in FIG. 4).

  The drive control circuit 12 repeats such control processing until the injection signal IJt becomes an injection stop command (injection signal “H” → “L”) (T3, T6: YES in FIG. 4). The drive control circuit 12 keeps the injector current substantially constant by repeating the power interruption to the injector in this way.

  When the drive control circuit 12 receives the injection stop command (L level) (T3 or T6: NO), the drive control circuit 12 stops the power interruption control by turning off the constant current control switch 15. Thereafter, the drive control circuit 12 does not start the power interruption control for the injector until the injection command (L → H) is input again as the injection signal IJt.

<Summary>
Up to now, the drive control circuit 12 initially controlled the pre-transistor 21nn to be turned off at the timing when a separately determined peak current detection threshold was detected. However, the drive control circuit 12 charges the gate capacitance of the P-channel MOS transistor 21n. It was difficult to instantaneously cut off the energization of the electromagnetic coil.

  In particular, the off-timing deviation due to manufacturing variations of the components (various resistors R1 to R4, various transistors 21nn and 21n) of the discharge switch 14 of the injector driving device 11 was large. Comparing the standard product (typ) with the off-timing deviation, the minimum value product (min), and the maximum value product (max), for example, the absolute value increases to about 20 μsec ± 30%, and the variation also increases. It has been confirmed that.

  According to this embodiment, the drive control circuit 12 first controls the MOS transistor 25m of the cylinder selection switch 16 on the downstream side to be turned off at the timing when the peak is detected. Then, the drain-source between the MOS transistors 25m on the downstream side can be interrupted, so that the energization of the electromagnetic coil of the injector can be instantaneously interrupted. According to the inventor, it has been confirmed that this off transition time is less than 1 μsec, and even if this time varies, for example, it has also been confirmed that injection control is not affected. For this reason, the control time can be significantly shortened as compared with the prior art, and the control process can be performed appropriately.

  Thereafter, after the pre-transistor 21nn is turned off, the drive control circuit 12 turns on the MOS transistor 25m of the cylinder selection switch 16 again when detecting that the detection voltage Vdeth of the resistor RH has reached the re-ON threshold value Vton. ing. Then, the energization of the electromagnetic coil of the injector can be started again, and the constant current control can be shifted from this timing.

  As a result, even when the discharge switch 14 is configured using the PMOS transistor 21n, it is possible to quickly shift to constant current control without being affected as much as possible by the element value variation of the components for driving the transistor.

  The on-timing of the constant-current power supply unit 15 (on-timing of the MOS transistor 22n of the constant-current control switch 15) is not limited to the timing of the above-described step S5. (Ie, between steps S6 and S7 in FIG. 3), after reaching the re-ON threshold value Vton, before the MOS transistor 25m of the cylinder selection switch 16 is turned on (ie, between steps S7 and S8 in FIG. 3). good. As a result, the same effects as described above can be obtained.

(Second Embodiment)
5 and 6 show a second embodiment. The second embodiment differs from the first embodiment in the control method. The same or similar parts as those in the first embodiment are denoted by the same or similar reference numerals, and the description thereof will be omitted. Only parts different from the first embodiment will be described in the second embodiment.

FIG. 5 shows a timing chart of a control method instead of FIG. 2, and FIG. 6 shows a flowchart of a control method alternative to FIG.
6 differs from FIG. 3 in that the processing order of step S5 and the determination process of step S10 are provided instead of the determination process of step S7. The drive control circuit 12 sequentially performs the control processes of steps S1, S2, S3, S4, S6, and S5, and then determines whether or not the detection value of the resistor RL has reached a predetermined value in step S10 (FIG. 6). S10). Then, the drive control circuit 12 turns on the MOS transistor 25m of the cylinder selection switch 16 on the condition that the detection value of the resistor RL has reached a predetermined value (S8 in FIG. 6).

  In the first and second embodiments, it is assumed that the injector driving device 11 has all the component element values set to the same value. Further, it is assumed that the re-ON threshold value Vton2 is set to the same value as the re-ON threshold value Vton described in the first embodiment.

  Under this condition, as shown in the timing “C” → “D2” period in FIG. 5, the rate of decrease in the detection voltage due to the resistor RH becomes faster than in the first embodiment. Then, in the control process of the second embodiment, the period TM2 from when the peak is detected until the MOS transistor 25m of the selection switch 16 is turned on again can be shortened compared to the first embodiment. That is, the period TM2 shown in FIG. 5 is shorter than the period TM1 shown in FIG. This is because the decreasing gradient of the detected value of the resistor RL is larger than the decreasing gradient of the detected value of the resistor RH.

  According to this embodiment, after the pre-transistor 21nn is turned off, the drive control circuit 12 turns on the MOS transistor 25m of the cylinder selection switch 16 when detecting that the detection voltage Vdetl of the resistor RL has reached the re-on threshold value Vton2. Turn on control again. Then, the energization of the electromagnetic coil of the injector can be started again, and the constant current control can be shifted from this timing.

  As a result, even when the discharge switch 14 is configured using the PMOS transistor 21n, the energization current of the electromagnetic coil is reduced to the peak current without being affected as much as possible by the element value variation of the component for driving the transistor. Can quickly shift to constant current control. Moreover, according to this embodiment, it can transfer to constant current control quicker than the control processing of 1st Embodiment.

  The on-timing of the MOS transistor 22n of the constant current control switch 15 is not limited to the timing of the above-described step S5, but after the MOS transistor 25m of the cylinder selection switch 16 is on-controlled and before the pre-transistor is turned off (that is, FIG. 6 between steps S4 and S6), after the current of the cylinder selection switch 16 reaches a predetermined value, before the MOS transistor 25m of the cylinder selection switch 16 is turned on (that is, between steps S10 and S8 in FIG. 6). You can go. Then, there exists an effect similar to the above-mentioned.

  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. Accordingly, the invention according to the present application is not limited to the reference numerals attached to the constituent elements of the claims, and it goes without saying that various expansions are possible within the terms of the claims or their equivalents. .

  In the drawing, 1 to 6 are injectors, 11 is an injector driving device, 12 is a drive control circuit (control circuit), 14 is a discharge switch, 16 is a cylinder selection switch, 21aa, 21bb and 21cc are pre-transistors, and 21n (21a and 21b). 21c) is a P-channel MOS transistor, 25m (25a to 25f) is an N-channel MOS transistor (cylinder selection switch), L1 to L6 are electromagnetic coils, RH is a resistor (first detection circuit), and RL is a resistor ( 2nd detection circuit).

Claims (4)

When the injection command signal is input, a peak current is applied in response to applying a boosted voltage to the electromagnetic coils (L1 to L6) of the injectors (1 to 6) provided for each cylinder of the internal combustion engine. A drive device for energizing a constant current lower than the peak current,
A pre-transistor (21aa, 21bb, 21cc) is connected to the gate of a P-channel MOS transistor (21a, 21b, 21c: hereinafter referred to as a PMOS transistor), and the boosted voltage is applied to the electromagnetic coil through an energization terminal of the PMOS transistor. A discharge switch (14) that is a switch that cuts off and on power, and that controls the pre-switch to be off when the PMOS transistor is turned off, thereby changing the control terminal of the PMOS transistor to the boost voltage;
A first detection circuit (RH) for detecting a discharge current of the boosted voltage;
A cylinder selection switch (16) for selecting the electromagnetic coil of the injector for each cylinder;
A second detection circuit (RL) connected in series to the cylinder selection switch and detecting an energization current of the cylinder selection switch;
A control circuit (12),
When the injection command signal is input, the control circuit (12) applies a boosted voltage to the electromagnetic coil of the injector by turning on the pre-transistor of the discharge switch (14) and the cylinder selection switch (16). And when the detection value of the second detection circuit (RL) reaches a first predetermined value (Vp) indicating a peak current, the cylinder selection switch (16) is turned off and then the discharge switch (14 ) Control off the pre-transistor,
An injector driving device characterized in that after the detection value of the first detection circuit (RH) reaches a second predetermined value (Vton), the cylinder selection switch (16) is turned on again to shift to constant current control. When the injection command signal is input, a peak current is applied in response to applying a boosted voltage to the electromagnetic coils (L1 to L6) of the injectors (1 to 6) provided for each cylinder of the internal combustion engine. It is a drive device that supplies a constant current lower than the peak current,
A pre-transistor (21aa, 21bb, 21cc) is connected to the gate of a P-channel MOS transistor (21a, 21b, 21c: hereinafter referred to as a PMOS transistor), and a boosted voltage is passed to the electromagnetic coil through an energization terminal of the PMOS transistor. A discharge switch (14) that is a switch for disconnecting electricity, and that controls the pre-transistor to turn off when the PMOS transistor is turned off, thereby changing the control terminal of the PMOS transistor to the boost voltage;
A cylinder selection switch (16) for selecting the electromagnetic coil of the injector for each cylinder;
A second detection circuit (RL) connected in series to the cylinder selection switch and detecting an energization current of the cylinder selection switch;
A control circuit (12),
When the injection command signal is input, the control circuit (12) applies a boosted voltage to the electromagnetic coil of the injector by turning on the pre-transistor of the discharge switch (14) and the cylinder selection switch (16). And when the detection value of the second detection circuit (RL) reaches a first predetermined value (Vp) indicating a peak current, the cylinder selection switch (16) is turned off and then the discharge switch (14 ) Control off the pre-transistor,
An injector driving device characterized in that after the detection value of the second detection circuit (RL) reaches a third predetermined value (Vton2), the cylinder selection switch (16) is turned on again to shift to constant current control. . A constant current control switch (15) for switching on and off a power supply voltage when the constant current is supplied to the electromagnetic coil;
The control circuit (12) is configured to turn on the constant current control switch (15) when a detection value of the first detection circuit (RH) reaches a second predetermined value (Vton). The injector drive device according to Item 1. A constant current control switch (15) for switching on and off a power supply voltage when the constant current is supplied to the electromagnetic coil;
The control circuit (12) turns on the constant current control switch (15) when a detection value of the second detection circuit (RL) reaches a third predetermined value (Vton2). Item 3. The injector driving device according to Item 2.

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