JP7307860B2 - Injection control device - Google Patents

Description

The present invention relates to an injection control device that controls driving of an injection device that injects fuel into an internal combustion engine.

In general, an injection control device controls the amount of fuel injected from an injection device by controlling the supply time (energization time) and current amount of a drive current to a solenoid that constitutes an injection valve of the injection device. In an injection control device, a voltage boosted by a booster circuit is applied to a booster capacitor to store electric charge, and the stored electrical energy is often used to supply a drive current to a solenoid. The injection control device supplies a large current (hereinafter also referred to as "peak current") necessary for opening the closed injection valve to the solenoid at the initial stage of energization of the solenoid to quickly open the injection valve. After that, the injection control device supplies a constant current (hereinafter also referred to as "open holding current") to the solenoid to keep the injection valve open.

In such an injection control device, once injection is performed, the charging voltage of the boosting capacitor may drop. After that, when the close injection is performed so that the next injection is performed before the charging of the boosting capacitor is completed, the drive voltage applied to the solenoid is lower than usual, and the time to reach the peak current becomes longer. As a result, the opening speed of the injection valve decreases, and there is a possibility that the amount of fuel to be injected varies greatly. Variation in the injected fuel amount affects the exhaust performance of the internal combustion engine.

Therefore, a technique for suppressing variations in the amount of injected fuel by providing a plurality of boosting capacitors, providing a switching element in the circuit from each boosting capacitor to the solenoid, and switching the boosting capacitor used for each injection by the switching element. is considered (for example, Patent Document 1).

Japanese Patent Application Laid-Open No. 2001-227392

However, in the technique described in Patent Document 1, since switching elements are interposed for all boost capacitors, the driving voltage applied to the solenoid is reduced due to energy loss in the switching elements regardless of the presence or absence of proximity injection. . In addition, the technique described in Patent Document 1 has room for further improvement in terms of driving voltage drop due to proximity injection. As a result, the technique described in Patent Literature 1 may decrease the valve opening speed of the injection valve and may not be able to suppress variations in the amount of fuel to be injected.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an injection control device capable of suppressing a decrease in the opening speed of an injection valve and suppressing variations in the amount of injected fuel. do.

In order to solve the above-described problems, an injection control device according to the present invention is an injection control device that controls driving of an injection device that injects fuel into an internal combustion engine by controlling a drive current that drives the injection device, comprising: a drive circuit for applying a drive voltage to the injection device and supplying the drive current to the injection device; a boosting capacitor for applying a voltage to the driving circuit; a switching element connected in series with the boosting capacitor; wherein the switching element switches the boosting capacitor and the auxiliary capacitor between a conducting state and a non-conducting state, and the auxiliary capacitor is switched to the conducting state with the boosting capacitor by the switching element. and the charging voltage of the boosting capacitor and the charging voltage of the auxiliary capacitor are applied to the drive circuit.

Advantageous Effects of Invention According to the present invention, it is possible to provide an injection control device capable of suppressing variations in the amount of injected fuel by suppressing a decrease in the valve opening speed of the injection valve.
Problems, configurations, and effects other than those described above will be clarified by the following description of the embodiments.

2 is a diagram for explaining the configuration of an injection control device according to Embodiment 1; FIG. FIG. 2 is a time chart for explaining the flow of drive current control in the injection control device shown in FIG. 1; FIG. 6 is a time chart for explaining the flow of drive current control in the injection control device of the second embodiment; The figure explaining the structure of the injection control apparatus of Embodiment 3. FIG. The figure explaining the structure of the injection control apparatus of Embodiment 4. FIG. FIG. 6 is a time chart for explaining the flow of drive current control in the injection control device shown in FIG. 5; FIG.

An embodiment of the present invention will be described below with reference to the drawings. It should be noted that components denoted by the same reference numerals in each embodiment have the same functions in each embodiment unless otherwise specified, and the description thereof will be omitted.

[Embodiment 1]
FIG. 1 is a diagram illustrating the configuration of an injection control device 10 according to Embodiment 1. As shown in FIG.

The injection control device 10 is a device that controls driving of the injection device 1 by controlling a drive current that drives the injection device 1 that injects fuel into the internal combustion engine. The injection control device 10 may be a device that controls driving of the injection device 1 in a cylinder direct injection internal combustion engine that directly injects fuel into the cylinder. The injection control device 10 may be a device that controls the driving of the injection device 1 capable of performing the proximity injection in which the next injection is performed before the charging of the boosting capacitor C1 is completed. The injection control device 10 may be a device that controls the driving of the injection device 1 capable of simultaneous multi-stage injection (for example, two-stage injection) of two opposing cylinders in an in-line four-cylinder direct injection internal combustion engine.

The injection control device 10 includes a booster circuit 11 , a drive circuit 12 , a conduction switching circuit 13 , an auxiliary charging circuit 14 and a control IC 15 .

The booster circuit 11 is a circuit that boosts the voltage of the battery VB. The boost circuit 11 includes an inductor L1, a diode D1, a switching element T3, and a boost capacitor C1.

One end of inductor L1 is connected to battery VB. The other end of inductor L1 is connected to the anode side of diode D1. A cathode side of the diode D1 is connected to the drive circuit 12 . The switching element T3 is composed of, for example, a transistor such as a MOSFET (metal-oxide-semiconductor field-effect transistor), and a free wheel diode is connected in anti-parallel to the transistor. A drain-side electrode of the switching element T3 is branched and connected from between the inductor L1 and the diode D1. A source-side electrode of the switching element T3 is connected to the ground. A gate-side electrode of the switching element T3 is connected to the control IC15. The boost capacitor C1 may be composed of, for example, an electrolytic capacitor. A high potential side electrode of the boosting capacitor C1 is branched from between the cathode side of the diode D1 and the driving circuit 12 and connected. A low-potential electrode of the boosting capacitor C1 is grounded. That is, boost capacitor C1 is connected in series with drive circuit 12 .

The charging voltage Vp of the boosting capacitor C1 is monitored by the control IC15. The control IC 15 controls the switching operation of the switching element T3 so that the charging voltage Vp of the boosting capacitor C1 reaches the target value of the driving voltage Vd of the injection device 1 during the boosting operation. The drive voltage Vd for the injector 1 is a voltage required to supply drive currents for driving the solenoids L2 to L5 constituting the injection valves of the injector 1 to the solenoids L2 to L5. Due to the switching operation of the switching element T3, an electromotive force is generated in the inductor L1, and the energy accumulated in the inductor L1 is transferred to the boosting capacitor C1 via the diode D1. The boosting capacitor C1 is charged with a boosted voltage boosted from the battery voltage VB based on the target value of the drive voltage Vd.

The drive circuit 12 is a circuit that applies a drive voltage Vd to the solenoids L2 to L5 of the injection device 1 and supplies a drive current to the solenoids L2 to L5 of the injection device 1 . The drive circuit 12 includes switching elements T4 to T9.

Each of the switching elements T4 to T9 is composed of a transistor such as a MOSFET, similarly to the switching element T3, and a free wheel diode is connected in anti-parallel to the transistor. The drain-side electrodes of the switching elements T4 and T5 are connected to the booster circuit 11 via the diode D2 of the conduction switching circuit 13 . A source-side electrode of the switching element T4 is connected to one end of each of the solenoids L2 and L3. A source-side electrode of the switching element T5 is connected to one end of each of the solenoids L4 and L5. A drain-side electrode of the switching element T6 is connected to the other end of the solenoid L2. A drain-side electrode of the switching element T7 is connected to the other end of the solenoid L3. Source-side electrodes of the switching elements T6 and T7 are grounded. A drain-side electrode of the switching element T8 is connected to the other end of the solenoid L4. A drain-side electrode of the switching element T9 is connected to the other end of the solenoid L5. Source-side electrodes of the switching elements T8 and T9 are grounded. Gate-side electrodes of the switching elements T4 to T9 are connected to the control IC15.

The switching elements T4-T9 perform switching operations for controlling the driving voltage Vd applied to the solenoids L2-L5. A control IC 15 controls the switching operations of the switching elements T4 to T9. The control IC 15 controls the switching elements T4 to T9 so that the driving voltage Vd corresponding to the peak current for quickly opening the closed injection valves of the injection device 1 is applied to the solenoids L2 to L5 at the start of valve opening. Controls switching behavior. As a result, the drive circuit 12 can supply the solenoids L2 to L5 with a peak current that quickly opens the closed injection valves of the injection device 1 as the drive current. After that, the control IC 15 applies a switching element provided in a constant current circuit (not shown) to the solenoids L2 to L5 so that the drive voltage Vd corresponding to the valve open holding current for maintaining the valve open state of the injection valve is applied. control the switching operation of In this embodiment, the conventional configuration can be used as the constant current circuit, so illustration and description thereof will be omitted.

The auxiliary charging circuit 14 is a circuit that assists the charging voltage Vp of the boosting capacitor C<b>1 applied to the drive circuit 12 . The auxiliary charging circuit 14 includes an auxiliary capacitor C2, a diode D3, a switching element T2, and a power supply Vcc.

Power supply Vcc is any DC power supply that charges auxiliary capacitor C2. The power supply Vcc may be the battery VB connected to the boosting capacitor C1, or may be a power supply different from the battery VB. When the power supply Vcc is different from the battery VB, the boosting capacitor C1 and the auxiliary capacitor C2 can be charged independently of each other, thereby shortening the charging time. Power supply Vcc is connected to the anode side of diode D3. The cathode side of the diode D3 is connected to the high potential side electrode of the auxiliary capacitor C2. The auxiliary capacitor C2 may be composed of, for example, an electrolytic capacitor like the boost capacitor C1. Similar to the switching element T3, the switching element T2 is composed of a transistor such as a MOSFET, and a free wheel diode is connected in anti-parallel to the transistor. A high potential side electrode of the auxiliary capacitor C2 is connected to the cathode side of the diode D3 and is also connected to the drive circuit 12 via the diode D4 of the conduction switching circuit 13 . The low potential side electrode of the auxiliary capacitor C2 is connected to the drain side electrode of the switching element T2, and is also connected to the high potential side electrode of the boosting capacitor C1 via the switching element T1 of the conduction switching circuit 13. . That is, the auxiliary capacitor C2 is connected in series with the switching element T1. The drain side electrode of the switching element T2 is connected to the low potential side electrode of the auxiliary capacitor C2. A source-side electrode of the switching element T2 is connected to the ground. A gate-side electrode of the switching element T2 is connected to the control IC 15 .

The charging voltage Vs of the auxiliary capacitor C2 is monitored by the control IC15. The control IC 15 controls the switching operation of the switching element T2 so that the charging voltage Vs of the auxiliary capacitor C2 reaches a predetermined target value when the auxiliary capacitor C2 is charged. The target value of the charging voltage Vs of the auxiliary capacitor C2 is a value capable of compensating for the decrease in the charging voltage Vp of the boosting capacitor C1 due to the proximity injection.

The switching element T2 performs a switching operation for switching whether to charge the auxiliary capacitor C2. When the switching element T2 is turned ON, the low-potential-side electrode of the auxiliary capacitor C2 and the ground are brought into a conductive state, and the charging voltage Vs of the auxiliary capacitor C2 increases. Auxiliary capacitor C2 is charged with an arbitrary power supply voltage Vcc predetermined based on the target value of charging voltage Vs. When the switching element T2 is turned off, the low-potential-side electrode of the auxiliary capacitor C2 and the ground are disconnected, and charging of the auxiliary capacitor C2 is stopped.

The conduction switching circuit 13 is a circuit that switches the boosting capacitor C1 and the auxiliary capacitor C2 between a conducting state and a non-conducting state. The conduction switching circuit 13 includes a switching element T1, a diode D2, and a diode D4.

Similar to the switching element T3, the switching element T1 is composed of a transistor such as a MOSFET, and a free wheel diode is connected in anti-parallel to the transistor. A drain-side electrode of the switching element T1 is branched from between the high-potential-side electrode of the boosting capacitor C1 and the drive circuit 12 and connected. That is, the switching element T1 is connected in series with the boosting capacitor C1. The source-side electrode of the switching element T1 is branched and connected from between the low-potential-side electrode of the auxiliary capacitor C2 and the drain-side electrode of the switching element T2. A gate-side electrode of the switching element T1 is connected to the control IC 15 . That is, the boosting capacitor C1 and the auxiliary capacitor C2 are connected in series via the switching element T1. The anode side of diode D2 is connected to drive circuit 12 . The anode side of diode D2 is connected to booster circuit 11 . A cathode side of the diode D2 is connected to the drive circuit 12 . The anode side of the diode D4 is connected to the high potential side electrode of the auxiliary capacitor C2. The cathode side of the diode D4 is branched from between the cathode side of the diode D2 and the driving circuit 12 and connected.

The switching element T1 performs a switching operation for switching the boosting capacitor C1 and the auxiliary capacitor C2 between a conducting state and a non-conducting state. The switching operation of the switching element T1 is controlled by the control IC15. When the switching element T1 is turned off, the boosting capacitor C1 and the auxiliary capacitor C2 are brought out of conduction. A charging voltage Vp of the boosting capacitor C1 is applied to the driving circuit 12, and a driving current is supplied to the driving circuit 12 from the charged boosting capacitor C1 through the diode D2. When the switching element T1 is turned ON, the boosting capacitor C1 and the auxiliary capacitor C2 are brought into conduction. A voltage corresponding to the sum of the charging voltage Vp of the boosting capacitor C1 and the charging voltage Vs of the auxiliary capacitor C2 is applied to the drive circuit 12, and the voltage is applied from the charged boosting capacitor C1 and auxiliary capacitor C2 via the switching element T1 and the diode D4. A drive current is supplied to the drive circuit 12 . That is, the auxiliary capacitor C2 applies the charging voltage Vp of the boosting capacitor C1 and the charging voltage Vs of the auxiliary capacitor C2 to the driving circuit 12 when switched to the boosting capacitor C1 by the switching element T1.

FIG. 2 is a time chart for explaining the flow of drive current control in the injection control device 10 shown in FIG.

In FIG. 2, the case where the solenoid L2 of the injection device 1 is driven twice will be described as an example. Before time t1 when the solenoid L2 starts to be driven for the first time (when the valve starts to open), both the boosting capacitor C1 and the auxiliary capacitor C2 are in a state of being fully charged. Prior to time t1, switching element T2 is ON. Before time t1, the switching element T1 is OFF, and the boosting capacitor C1 and the auxiliary capacitor C2 are in a non-conducting state. Further, in FIG. 2, at time t4 when the solenoid L2 starts to be driven for the second time (when the valve starts to open), it is assumed that charging of the boosting capacitor C1 is not completed, and the injector 1 performs proximity injection. It is assumed that

The control IC 15 turns on the switching elements T4 and T6 at time t1 when the solenoid L2 starts to be driven for the first time (when the valve starts to open). Since the switching element T1 is OFF, the driving voltage Vd corresponding to the charging voltage Vp of the boosting capacitor C1 is applied to the solenoid L2. A current is supplied to the solenoid L2 from the charged boosting capacitor C1 via the diode D2. That is, the drive circuit 12 supplies the solenoid L2 of the injection device 1 with a peak current for opening the closed injection valve of the injection device 1 as a drive current by the charging voltage Vp of the boosting capacitor C1. The charging voltage Vp of the boosting capacitor C1 drops due to discharging. The driving voltage Vd applied to the solenoid L2 decreases as the charging voltage Vp of the boosting capacitor C1 decreases.

The control IC 15 turns off the switching element T4 at time t2 when the peak current is supplied to the solenoid L2. The injection valve of the injection device 1, which is constituted by the solenoid L2, opens to inject fuel. The charging voltage Vp of the boosting capacitor C1 is charged from the boosting circuit 11 and rises. The drive voltage Vd applied to the solenoid L2 rises as the charging voltage Vp of the boosting capacitor C1 rises.

Note that the control IC 15 turns on the switching element provided in the constant current circuit at time t2. A valve open holding current is supplied to the solenoid L2 from a constant current circuit. The injection valve of the injection device 1, which is constituted by the solenoid L2, maintains the valve open state and continues to inject fuel. The control IC 15 turns off the switching element T6 at time t3 after the time (holding time of the valve open state) for the amount of fuel injected from the injection device 1 configured by the solenoid L2 to reach the target value. The solenoid L2 stops supplying the valve-open holding current. The injection valve of the injection device 1, which is constituted by the solenoid L2, closes to stop the injection of fuel. In FIG. 2, illustration of transition of the drive voltage Vd when the valve-open holding current is supplied is omitted.

Here, the time t4 when the solenoid L2 starts to be driven for the second time (when the valve starts to open) is the time when the solenoid L2 of the injection device 1 is supplied with the peak current. In this embodiment, charging of the boosting capacitor C1 is not completed at time t4. A state in which charging of the boosting capacitor C1 is not completed is, for example, a state in which the charging voltage Vp of the boosting capacitor C1 is lower than the first threshold value Vpt based on the peak current.

The first threshold Vpt is the voltage value obtained by subtracting the charging voltage Vs that can be compensated by the auxiliary capacitor C2 from the charging voltage Vp of the boosting capacitor C1 necessary for applying the driving voltage Vd corresponding to the peak current to the solenoid L2. may also be a large value. The first threshold Vpt may be, for example, a voltage value equivalent to 90% of the charging voltage Vp of the boosting capacitor C1 required for applying the driving voltage Vd corresponding to the peak current to the solenoid L2.

At time t4, the control IC 15 turns on the switching element T1 and turns off the switching element T2. The boosting capacitor C1 and the auxiliary capacitor C2 are brought into a conductive state. That is, when a peak current is supplied to the solenoid L2 of the injection device 1, the switching element T1 switches between the boost capacitor C1 and The auxiliary capacitor C2 is switched to a conducting state. Then, the control IC 15 turns on the switching elements T4 and T6 at time t4. A driving voltage Vd corresponding to the sum of the charging voltage Vp of the boosting capacitor C1 and the charging voltage Vs of the auxiliary capacitor C2 is applied to the solenoid L2. A drive current is supplied to the solenoid L2 from the charged boosting capacitor C1 and the auxiliary capacitor C2 via the switching element T1 and the diode D4. The charging voltage Vp of the boosting capacitor C1 drops due to discharging. The charging voltage Vs of the auxiliary capacitor C2 decreases due to discharging. The driving voltage Vd applied to the solenoid L2 decreases as the charging voltage Vp of the boosting capacitor C1 and the charging voltage Vs of the auxiliary capacitor C2 decrease.

The control IC 15 turns off the switching element T4 at time t5 when the peak current is supplied to the solenoid L2. The injection valve of the injection device 1, which is constituted by the solenoid L2, opens to inject fuel. At time t5, the control IC 15 turns off the switching element T1 and turns on the switching element T2. The boosting capacitor C1 and the auxiliary capacitor C2 are brought into a non-conducting state. That is, after the peak current is supplied to the solenoid L2 of the injector 1, the switching element T1 switches the boosting capacitor C1 and the auxiliary capacitor C2 to a non-conducting state. The charging voltage Vp of the boosting capacitor C1 is charged from the boosting circuit 11 and rises. The charge voltage Vs of the auxiliary capacitor C2 is charged from the power supply Vcc and rises. The drive voltage Vd applied to the solenoid L2 rises as the charging voltage Vp of the boosting capacitor C1 rises.

At time t5, the control IC 15 turns ON the switching element provided in the constant current circuit to supply the valve open holding current from the constant current circuit to the solenoid L2, as at time t2. At time t6, the control IC 15 turns off the switching element T6 to stop supplying the valve-open holding current, as at time t3. In FIG. 2, the case where the solenoid L2 of the injection device 1 is driven twice has been described as an example. , operates in the same manner as described in FIG.

As described above, the injection control device 10 of Embodiment 1 is an injection control device that controls driving of the injection device 1 by controlling the drive current that drives the injection device 1 that injects fuel into the internal combustion engine. The injection control device 10 includes a drive circuit 12 that applies an injection device 1 drive voltage Vd to supply a drive current to the injection device 1 . The injection control device 10 includes a boosting capacitor C<b>1 that is charged with a boosted voltage boosted from the voltage of the battery VB based on the drive voltage Vd and applies the charging voltage Vp to the drive circuit 12 . The injection control device 10 includes a switching element T1 connected in series with the boosting capacitor C1, and an auxiliary circuit connected in series with the switching element T1, charged with the voltage of an arbitrary power supply Vcc, and applying a charging voltage Vs to the drive circuit 12. and a capacitor C2. The switching element T1 switches the boosting capacitor C1 and the auxiliary capacitor C2 between a conducting state and a non-conducting state. The auxiliary capacitor C2 applies the charging voltage Vp of the boosting capacitor C1 and the charging voltage Vs of the auxiliary capacitor C2 to the driving circuit 12 when switched to the boosting capacitor C1 by the switching element T1.

As a result, when the charged voltage Vp of the boosting capacitor C1 drops below the voltage at the completion of charging due to proximity injection or the like, the injection control device 10 of the first embodiment replaces the drop in the charged voltage Vp with the charged voltage Vs of the auxiliary capacitor C2. can be compensated by Therefore, the injection control device 10 of the first embodiment has the time required for the driving current supplied to the solenoids L2 to L5 of the injection device 1 to reach the peak current (from the time t4 to the time t5) due to the decrease in the charging voltage Vp. time) can be suppressed from being longer than usual. Therefore, the injection control device 10 of Embodiment 1 can suppress a decrease in the valve opening speed of the injection valve, thereby suppressing variations in the amount of injected fuel.

Moreover, the injection control device 10 of the first embodiment turns off the switching element T1 when the charged voltage Vp of the boosting capacitor C1 does not drop below the voltage at the completion of charging due to proximity injection or the like, and the boosting capacitor C1 and the auxiliary capacitor C2 can be made non-conducting. In this case, the injection control device 10 of Embodiment 1 can have a circuit configuration in which a switching element is not interposed between the boosting capacitor C1 and the drive circuit 12 . Therefore, in this case, in the injection control device 10 of the first embodiment, the charging voltage Vp of the boosting capacitor C1 drops due to energy loss in the switching elements, and the driving voltage Vd applied to the solenoids L2 to L5 of the injection device 1 becomes It is possible to suppress the decrease. Therefore, the injection control device 10 of Embodiment 1 can suppress a decrease in energy efficiency, suppress a decrease in the valve opening speed of the injection valve, and suppress variations in the amount of injected fuel.

In particular, the injection control device 10 of the first embodiment supplies the solenoids L2 to L5 of the injection device 1 with a peak current for opening the injection valves of the injection device 1 whose drive circuit 12 has closed, as the drive current. When a peak current is supplied to the injection device 1, the switching element T1 switches between the boost capacitor C1 and the auxiliary capacitor C2 if the charging voltage Vp of the boost capacitor C1 is lower than the first threshold value Vpt based on the peak current. Switch to the conducting state.

As a result, when the injection control device 10 of the first embodiment requires a large peak current to open the injection valve of the closed injection device 1, the charging voltage Vp of the boosting capacitor C1 becomes insufficient. However, this can be reliably compensated for by the auxiliary capacitor C2. Therefore, the injection control device 10 of the first embodiment can reliably suppress the decrease in the valve opening speed of the injection valve and reliably suppress variations in the amount of injected fuel.

[Other embodiments]
Other embodiments 2 to 4 of the injection control device 10 will be described with reference to FIGS. 3 to 6. FIG. In the description of the second to fourth embodiments, descriptions of the same configurations and operations as those of the first embodiment are omitted.

FIG. 3 is a time chart for explaining the flow of drive current control in the injection control device 10 of the second embodiment. FIG. 3 corresponds to FIG.

The control IC 15 of the first embodiment turns off the switching element T1 and turns on the switching element T2 at time t5. That is, the control IC 15 of the first embodiment switches the boosting capacitor C1 and the auxiliary capacitor C2 to a non-conducting state at time t5 when the peak current is supplied to the solenoids L2 to L5, and starts charging the auxiliary capacitor C2. . In contrast, after time t4 and before time t5, the control IC 15 of the second embodiment turns off the switching element T1, turns on the switching element T2, and disconnects the boost capacitor C1 and the auxiliary capacitor C2. It may switch to a conductive state and start charging the auxiliary capacitor C2.

Specifically, when the charging voltage Vs of the auxiliary capacitor C2 is equal to or lower than the second threshold Vst based on the discharge end voltage of the auxiliary capacitor C2, the control IC 15 of the second embodiment controls the voltage boosting capacitor C1 and the auxiliary capacitor C2. to a non-conducting state to start charging the auxiliary capacitor C2. That is, when the boosting capacitor C1 and the auxiliary capacitor C2 are in a conductive state, the switching element T1 is set to , the boosting capacitor C1 and the auxiliary capacitor C2 may be switched to a non-conducting state.

The end-of-discharge voltage of the auxiliary capacitor C2 is the minimum discharge voltage at which the auxiliary capacitor C2 can safely discharge. The second threshold Vst may be a voltage value obtained by adding a predetermined margin to the final discharge voltage of the auxiliary capacitor C2. The second threshold Vst may be, for example, a predetermined voltage value at which the charging voltage Vs of the auxiliary capacitor C2 falls within a range of greater than 0V and less than or equal to 1V. When the charging voltage Vs of the auxiliary capacitor C2 becomes equal to or lower than the second threshold value Vst, it means that the energy stored in the auxiliary capacitor C2 is substantially lost and the compensation effect of the auxiliary capacitor C2 is substantially lost.

As shown in FIG. 3, the control IC 15 of the second embodiment, at time Ta when the charging voltage Vs of the auxiliary capacitor C2 becomes equal to or lower than the second threshold value Vst, switches the switching element even before the peak current is supplied to the solenoid L2. T1 is turned off and the switching element T2 is turned on. The boosting capacitor C1 and the auxiliary capacitor C2 are switched to a non-conducting state, and charging of the auxiliary capacitor C2 is started.

As described above, the injection control device 10 of the second embodiment can bring the boosting capacitor C1 and the auxiliary capacitor C2 into a non-conducting state when the compensation effect of the auxiliary capacitor C2 is substantially lost. In this case, the injection control device 10 of the second embodiment can have a circuit configuration in which no switching element is interposed between the boosting capacitor C1 and the drive circuit 12. FIG. Therefore, in this case, the injection control device 10 of the second embodiment covers the driving voltage Vd only with the charging voltage Vp of the boosting capacitor C1, so that the energy loss in the switching element T1 and the auxiliary capacitor C2 can be suppressed. can be done. Therefore, the injection control device 10 of the second embodiment can suppress a decrease in energy efficiency, suppress a decrease in the valve opening speed of the injection valve, and suppress variation in the amount of injected fuel.

FIG. 4 is a diagram illustrating the configuration of the injection control device 10 of Embodiment 3. As shown in FIG. FIG. 4 corresponds to FIG.

The auxiliary capacitor C2 of Embodiment 1 was charged by the voltage of the power supply Vcc. In contrast, the auxiliary capacitor C<b>2 of the third embodiment may be charged with a boosted voltage boosted from the voltage of the battery VB by the booster circuit 11 .

Specifically, in the auxiliary charging circuit 14 of Embodiment 3, the high potential side electrode of the auxiliary capacitor C2 is connected to the cathode side of the diode D2, and the diode D3 and the power supply Vcc are excluded. The diode D4 is excluded from the conduction switching circuit 13 of the third embodiment. The auxiliary capacitor C2 is charged with a boosted voltage boosted from the battery voltage VB by the booster circuit 11, similarly to the boosting capacitor C1.

As described above, the injection control device 10 of the third embodiment can achieve the same effects as those of the first embodiment, and can reduce the number of elements compared to the first embodiment. That is, since the injection control device 10 of the third embodiment can reduce the number of elements, it is possible to reduce the size of the device and improve the energy efficiency as compared with the first embodiment.

FIG. 5 is a diagram illustrating the configuration of the injection control device 10 of the fourth embodiment. FIG. 5 corresponds to FIG.

In the auxiliary charging circuit 14 of Embodiment 1, the low potential side electrode of the auxiliary capacitor C2 is connected to the high potential side electrode of the boosting capacitor C1 via the switching element T1. On the other hand, in the auxiliary charging circuit 14 of the fourth embodiment, the high potential side electrode of the auxiliary capacitor C2 may be connected to the low potential side electrode of the boosting capacitor C1 via the switching element T11.

Specifically, the diode D3 is excluded from the auxiliary charging circuit 14 of the fourth embodiment. The conduction switching circuit 13 of the fourth embodiment includes a switching element T11 instead of the switching element T1, a switching element T12, and the diode D2 and the diode D4 are excluded.

Similar to the switching element T1, the switching element T11 performs a switching operation of switching between the conducting state and the non-conducting state between the boosting capacitor C1 and the auxiliary capacitor C2. The switching element T12 performs a switching operation for switching whether or not to charge the boosting capacitor C1. When the switching element T12 is turned on, the low-potential-side electrode of the boosting capacitor C1 and the ground are brought into conduction, and the charging voltage Vp of the boosting capacitor C1 increases. When the switching element T12 is turned off, the low-potential-side electrode of the boosting capacitor C1 is disconnected from the ground, and charging of the boosting capacitor C1 is stopped.

The injection control device 10 of Embodiment 4 comprises another switching element T12 different from the switching elements T1 and T11. A high potential side electrode of the boosting capacitor C1 is connected to the drive circuit 12 . The low potential side electrode of the boosting capacitor C1 is connected to the high potential side electrode of the auxiliary capacitor C2 via the switching element T11. The electrode on the low potential side of the auxiliary capacitor C2 is connected to the ground. A switching element T12 different from the switching elements T1 and T11 is branched from between the low potential side electrode of the boosting capacitor C1 and the switching element T11, and connected to the low potential of the auxiliary capacitor C2 through the ground. connected to the side electrode.

Specifically, the low-potential-side electrode of the boosting capacitor C1 is connected to the drain-side electrode of the switching element T12 and to the source-side electrode of the switching element T11. A source-side electrode of the switching element T12 is connected to the ground. A gate-side electrode of the switching element T12 is connected to the control IC15. The drain-side electrode of the switching element T11 is connected to the high-potential-side electrode of the auxiliary capacitor C2 and to the source-side electrode of the switching element T2. A gate-side electrode of the switching element T11 is connected to the control IC15. The electrode on the low potential side of the auxiliary capacitor C2 is connected to the ground. A drain-side electrode of the switching element T2 is connected to the power supply Vcc. A gate-side electrode of the switching element T2 is connected to the control IC 15 .

FIG. 6 is a time chart for explaining the flow of drive current control in the injection control device 10 shown in FIG. FIG. 6 corresponds to FIG.

The control IC 15 of the fourth embodiment controls the switching operation of the switching element T11 in the same manner as the switching element T1 of the first embodiment. The control IC 15 of the fourth embodiment controls the switching operation of the switching element T12 in the same manner as the switching element T2 of the first and fourth embodiments.

That is, the control IC 15 of the fourth embodiment turns off the switching element T11 and turns on the switching elements T2 and T12 before time t1. Before time t1, both the boosting capacitor C1 and the auxiliary capacitor C2 are in a state of being fully charged.

The control IC 15 of the fourth embodiment turns on the switching element T11 and turns off the switching elements T2 and T12 at time t4. At time t4, the boosting capacitor C1 and the auxiliary capacitor C2 become conductive, and the driving voltage Vd corresponding to the sum of the charging voltage Vp of the boosting capacitor C1 and the charging voltage Vs of the auxiliary capacitor C2 is applied to the solenoid L2. .

The control IC 15 of the fourth embodiment turns off the switching element T11 and turns on the switching elements T2 and T12 at time t5. At time t5, the boosting capacitor C1 and the auxiliary capacitor C2 become non-conductive, and the charging voltage Vp of the boosting capacitor C1 is charged by the booster circuit 11 and rises. The charging voltage Vs of the auxiliary capacitor C2 is charged by the power supply Vcc and rises.

As described above, the injection control device 10 of the fourth embodiment has the same effect as the first embodiment, and can reduce the number of elements compared to the fourth embodiment. That is, since the injection control device 10 of the fourth embodiment can reduce the number of elements, it is possible to reduce the size of the device and improve the energy efficiency as compared with the fourth embodiment.

[others]
In addition, the present invention is not limited to the above-described embodiments, and includes various modifications. For example, the above embodiments have been described in detail in order to explain the present invention in an easy-to-understand manner, and are not necessarily limited to those having all the configurations described. Moreover, it is possible to replace part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. Moreover, it is possible to add, delete, or replace a part of the configuration of each embodiment with another configuration.

Further, each of the configurations, functions, processing units, processing means, etc. described above may be realized by hardware, for example, by designing a part or all of them using an integrated circuit. Moreover, each of the above configurations, functions, etc. may be realized by software by a processor interpreting and executing a program for realizing each function. Information such as programs, tapes, and files that implement each function can be stored in recording devices such as memories, hard disks, SSDs (solid state drives), or recording media such as IC cards, SD cards, and DVDs.

Further, the control lines and information lines indicate those considered necessary for explanation, and not all control lines and information lines are necessarily indicated on the product. In practice, it may be considered that almost all configurations are interconnected.

Reference Signs List 1 injection device 10 injection control device 12 drive circuit C1 boosting capacitor C2 auxiliary capacitor T1 switching element T11 switching element T12 switching element VB battery Vcc power supply Vd ... drive voltage, Vp ... charging voltage of boosting capacitor, Vpt ... first threshold, Vs ... charging voltage of auxiliary capacitor, Vst ... second threshold

Claims (4)

An injection control device for controlling driving of an injection device for injecting fuel into an internal combustion engine by controlling a drive current for driving the injection device,
a driving circuit that applies a driving voltage to the injection device and supplies the driving current to the injection device;
a boosting capacitor connected to the drive circuit, charged with a boosted voltage boosted from a battery voltage based on the drive voltage, and applying the charged voltage to the drive circuit;
a switching element connected in series with the boosting capacitor;
an auxiliary capacitor connected in series with the switching element, charged with an arbitrary power supply voltage, and applying the charging voltage to the drive circuit;
with
the switching element switches the boosting capacitor and the auxiliary capacitor between a conducting state and a non-conducting state;
when the auxiliary capacitor is switched to the conductive state with the boosting capacitor by the switching element, the charging voltage of the boosting capacitor and the charging voltage of the auxiliary capacitor are applied to the drive circuit;
The drive circuit supplies, as the drive current, a peak current for opening the injection valve of the closed injection device to the injection device,
The switching element switches between the boost capacitor and the auxiliary capacitor when the charging voltage of the boost capacitor is below a first threshold value based on the peak current when the peak current is supplied to the injector. to the conducting state
An injection control device characterized by: When the charging voltage of the auxiliary capacitor is equal to or less than a second threshold value based on the end-of-discharge voltage of the auxiliary capacitor when the boosting capacitor and the auxiliary capacitor are in the conductive state, the switching element is configured to: 2. The injection control device according to claim 1 , wherein the boosting capacitor and the auxiliary capacitor are switched to the non-conducting state. The injection control device according to claim 1, wherein the arbitrary power supply voltage is the boosted voltage. Further comprising another switching element different from the switching element,
an electrode on the high potential side of the boosting capacitor is connected to the driving circuit;
the electrode on the low potential side of the boosting capacitor is connected to the electrode on the high potential side of the auxiliary capacitor via the switching element,
the electrode on the low potential side of the auxiliary capacitor is connected to ground;
The other switching element is branched and connected from between the low potential side electrode of the boosting capacitor and the switching element, and the low potential side electrode of the auxiliary capacitor via the ground. 2. The injection control device according to claim 1, wherein the injection control device is connected to .

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