JP7534578B2 - Injector Control Unit - Google Patents

Description

The present invention relates to an injector control device that controls the operation of an injector that injects fuel.

At the beginning of fuel injection, the injector control device supplies a boosted voltage obtained by boosting the voltage supplied from the battery, i.e., the charge voltage of the capacitor, to the injector solenoid coil to open the injector valve. The injector control device then supplies a voltage lower than the charge voltage supplied at the beginning of fuel injection, i.e., the voltage supplied from the battery, to the solenoid coil to keep the injector valve open. Then, when a preset injector current time has elapsed since the injector current began to flow, the injector control device stops supplying voltage to the solenoid coil and closes the injector valve to stop fuel injection.

Patent Document 1 discloses a high-pressure injector control device as such an injector control device. The injection time correction means of the high-pressure injector control device described in Patent Document 1 corrects the injection setting time of the injector based on the boosting capacity, which indicates the amount of energy stored in the capacitor per unit time. The high-pressure injector control device described in Patent Document 1 can suppress variations in the injection amount.

However, according to the knowledge obtained by the present inventor, even if the injection setting time of the injector is corrected based on the boosting ability, there are cases where the variation in the fuel injection amount cannot be suppressed. For example, when a multi-stage injection is performed in which the fuel injection is divided into multiple injections for the purpose of noise reduction, etc., there are cases where the variation in the fuel injection amount cannot be suppressed in the pre-injection in which minute fuel injection is performed. Note that the variation in the fuel injection amount may not be suppressed not only in the case of pre- injection but also in the case of main injection.

JP 2016-113955 A

The present invention has been made to solve the above problems, and aims to provide an injector control device that can improve the accuracy of correcting variations in fuel injection amount.

The above problem is solved by an injector control device according to the present invention, which is an injector control device that controls the operation of an injector that injects fuel, and is characterized by comprising: a charge voltage control circuit that stores electrical energy in the capacitor based on the voltage supplied from a battery when the charge voltage of the capacitor falls below a charge start threshold, and stops storing the electrical energy when the charge voltage reaches a charge completion threshold; a charge voltage detection unit that detects the charge voltage; a current flow time correction unit that acquires the charge voltage detected by the charge voltage detection unit, grasps the variation in the charge start threshold or the charge completion threshold based on the charge voltage acquired from the charge voltage detection unit, and corrects the current flow time of the injector according to the variation in the charge start threshold or the charge completion threshold; and an injector control circuit that controls the operation of the injector based on the charge voltage supplied from the charge voltage control circuit and the current flow time corrected by the current flow time correction unit.

According to the injector control device of the present invention, the current conduction time correction unit acquires the charge voltage detected by the charge voltage detection unit, and grasps the variation in the charge start threshold or the charge completion threshold based on the charge voltage acquired from the charge voltage detection unit. The charge start threshold is the charge voltage of the capacitor when the charge voltage control circuit starts storing electrical energy in the capacitor. The charge completion threshold is the charge voltage of the capacitor when the charge voltage control circuit stops storing electrical energy in the capacitor, i.e., the charge voltage of the capacitor when charging of the capacitor is completed. In addition, the current conduction time correction unit corrects the current conduction time of the injector according to the variation in the charge start threshold or the charge completion threshold. Then, the injector control circuit controls the drive of the injector based on the charge voltage supplied from the charge voltage control circuit and the current conduction time of the injector corrected by the current conduction time correction unit.

Here, according to the knowledge obtained by the inventor, the value of the charge voltage of the capacitor at the start of energization of the injector affects the fuel injection amount. Also, the time it takes for the value of the charge voltage of the capacitor to drop from the charge completion threshold to the charge start threshold due to natural discharge of the capacitor when the injector is not energized is much longer than the energization time of the injector and the time interval between fuel injections. Therefore, the variation in the charge completion threshold has a large effect on the value of the charge voltage of the capacitor at the start of energization of the injector. Also, since the variation in the charge completion threshold is equal to the variation in the charge start threshold, the variation in the charge start threshold also has a large effect on the value of the charge voltage of the capacitor at the start of energization of the injector. Then, the injector control device according to the present invention corrects the energization time of the injector according to the variation in the charge start threshold or the charge completion threshold, which has a large effect on the value of the charge voltage of the capacitor at the start of energization of the injector. As a result, the injector control device according to the present invention can improve the correction accuracy of the variation in the fuel injection amount.

In the injector control device according to the present invention, preferably, the current flow time correction unit obtains the charge voltage when the injector is not current-flowing from the charge voltage detection unit, and grasps the variation in the charge start threshold or the charge completion threshold by performing statistical processing of the charge voltage obtained from the charge voltage detection unit.

According to the injector control device of the present invention, the current flow time correction unit grasps the variation in the charge start threshold or charge completion threshold by performing statistical processing of the charge voltage obtained from the charge voltage detection unit when the injector is not energized. This allows the current flow time correction unit to accurately grasp the variation in the charge start threshold or charge completion threshold by simple processing when the injector is not driven.

In the injector control device according to the present invention, preferably, the current flow time correction unit obtains from the charge voltage detection unit a plurality of the charge start thresholds or the charge completion thresholds in a plurality of cycles of charging and discharging the capacitor that occur when the injector is not current-flowing, and grasps the variation in the charge start thresholds or the charge completion thresholds by calculating the average value of the plurality of the charge start thresholds or the charge completion thresholds obtained from the charge voltage detection unit.

According to the injector control device of the present invention, the current flow time correction unit grasps the variation in the charge start threshold or charge completion threshold by calculating the average value of multiple charge start thresholds or charge completion thresholds, so that the variation in the charge start threshold or charge completion threshold can be grasped accurately by simple processing, and the accuracy of correction of the variation in the fuel injection amount can be further improved.

In the injector control device according to the present invention, preferably, the current flow time correction unit obtains from the charge voltage detection unit a plurality of the charge start thresholds or the charge completion thresholds in a plurality of cycles of charging and discharging the capacitor that occurs when the injector is not current-flowing, and obtains the variation in the charge start thresholds or the charge completion thresholds by calculating the average value of the remaining plurality of the charge start thresholds or the charge completion thresholds obtained from the charge voltage detection unit after removing the maximum and minimum values from the plurality of the charge start thresholds or the charge completion thresholds.

According to the injector control device of the present invention, the current flow time correction unit grasps the variation in the charge start threshold or charge completion threshold by calculating the average value of the remaining multiple charge start thresholds or charge completion thresholds, excluding the maximum and minimum values from among the multiple charge start thresholds or charge completion thresholds. This makes it possible to accurately grasp the variation in the charge start threshold or charge completion threshold through simple processing, and further improves the accuracy of correction of the variation in the fuel injection amount.

The injector control device according to the present invention preferably further includes a storage unit that stores the current flow time corrected by the current flow time correction unit, and the injector control circuit controls the drive of the injector based on the current flow time corrected by the current flow time correction unit and stored in the storage unit.

According to the injector control device of the present invention, the injector control circuit controls the drive of the injector based on the injector current conduction time corrected by the current conduction time correction unit and pre-stored in the storage unit. Therefore, the injector control circuit can control the drive of the injector at a faster processing speed based on the more accurate injector current conduction time.

In the injector control device according to the present invention, preferably, the current flow time correction unit corrects the current flow time during the production process, and the storage unit stores the current flow time corrected by the current flow time correction unit during the production process.

According to the injector control device of the present invention, the current flow time correction unit corrects the current flow time of the injector during the production process. The storage unit stores the current flow time of the injector corrected by the current flow time correction unit during the production process. As a result, even if the electronic control unit (ECU: Electronic Control Unit) is replaced, the injector control device that functions as part of the replaced electronic control unit can improve the accuracy of correction of the variation in the fuel injection amount. Therefore, the electronic control unit can be easily replaced in the market after the injector control device is shipped from the factory.

In the injector control device according to the present invention, preferably, the current flow time correction unit corrects the current flow time in the market after the injector is shipped from the factory, and the memory unit stores the current flow time corrected by the current flow time correction unit in the market.

According to the injector control device of the present invention, the current flow time correction unit corrects the current flow time of the injector in the market after it is shipped from the factory. The memory unit stores the current flow time of the injector corrected in the market by the current flow time correction unit. As a result, even if the charge start threshold or charge completion threshold changes in the market due to, for example, deterioration of the capacitor over time, the injector control device of the present invention can improve the accuracy of correction of the variation in the fuel injection amount.

The present invention provides an injector control device that can improve the accuracy of correcting variations in fuel injection amount.

1 is a block diagram showing a configuration of a main part of an injector control device according to an embodiment of the present invention; 5 is a graph illustrating an example of a charge voltage when the injector of the present embodiment is not energized. 11 is a graph illustrating the variation in the charge start threshold value and the charge completion threshold value. 5 is a timing chart illustrating an example of the operation of the injector control device according to the present embodiment. 5 is a flowchart illustrating a specific example of a process executed by a current application time correction unit according to the present embodiment.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.
The embodiments described below are preferred specific examples of the present invention, and therefore various technically preferable limitations are applied to them, but the scope of the present invention is not limited to these aspects unless otherwise specified in the following description to the effect that the present invention is limited to them. In addition, in each drawing, similar components are given the same reference numerals, and detailed descriptions thereof are omitted as appropriate.

FIG. 1 is a block diagram showing a configuration of a main part of an injector control device according to an embodiment of the present invention.
The injector control device 2 according to this embodiment is mounted on, for example, a pre-chamber internal combustion engine, and controls the driving of an injector 4 that injects fuel. As shown in Fig. 1, the injector control device 2 according to this embodiment includes a microcomputer (hereinafter, for convenience of explanation, referred to as "microcomputer") 21, a charge voltage control circuit 22, a charge voltage detection unit 23, an injector control circuit 24, and a storage unit 25, and functions as a part of an electronic control unit (ECU). In the following explanation, for convenience of explanation, the microcomputer will be referred to as "microcomputer".

Engine operation information 3 detected by various sensors is input to the injector control device 2. As shown in FIG. 1, the engine operation information 3 includes, for example, a rotation signal related to the engine speed and a signal related to the driver's request such as the accelerator opening.

As described above, the injector control device 2 controls the operation of the injector 4. The injector 4 has a structure of a normally closed solenoid valve. For example, the injector 4 has a solenoid coil, a plunger, a return spring, and a needle valve. When a voltage is supplied to the solenoid coil based on a control signal transmitted from the injector control device 2, the solenoid coil becomes an electromagnet and attracts the plunger while resisting the biasing force of the return spring. Then, the needle valve opens. As a result, the fuel is injected from the nozzle hole provided at the tip of the injector 4. On the other hand, when the supply of voltage to the solenoid coil is stopped based on the control signal transmitted from the injector control device 2, the magnetic force of the solenoid coil is lost. Then, the plunger and the needle valve return to their original positions under the biasing force of the return spring, and the nozzle hole is closed. This stops the fuel injection.

The microcomputer 21 functions as a CPU (Central Processing Unit) and executes various calculations and processes by reading out programs stored in the storage unit 25. The microcomputer 21 also has a current-flow time correction unit 211 that corrects the current-flow time of the injector 4. Details of the current-flow time correction unit 211 will be described later.

The charge voltage control circuit 22 functions as a so-called boost circuit and includes a coil, a capacitor, a switching element such as a transistor, and a rectifying element such as a diode. The charge voltage control circuit 22 switches the switching element on and off to boost the voltage supplied from the battery and store electrical energy in the capacitor. In other words, the charge voltage control circuit 22 stores electrical energy in the capacitor based on the voltage supplied from the battery.

The charge voltage detection unit 23 detects the voltage of the capacitor, i.e., the charge voltage, and transmits a signal related to the detected charge voltage of the capacitor to the microcomputer 21.
The current supply time correction unit 211 obtains the charge voltage of the capacitor detected by the charge voltage detection unit 23 , and sets the current supply time of the injector 4 based on the charge voltage of the capacitor obtained from the charge voltage detection unit 23 .

The injector control circuit 24 controls the operation of the injector 4 based on the charge voltage supplied from the charge voltage control circuit 22 and the energization time set by the energization time correction unit 211. For example, at the beginning of fuel injection, the injector control circuit 24 supplies a boosted voltage obtained by boosting the voltage supplied from the battery, i.e., the charge voltage of the capacitor, to the solenoid coil of the injector 4 to open the needle valve of the injector 4. In other words, the boosted voltage generated by the charge voltage control circuit 22, i.e., the charge voltage, is supplied to the injector 4 via the injector control circuit 24. In addition, when the energization time set by the energization time correction unit 211 has elapsed from the time when the injector 4 starts to be energized (i.e., the time when the supply of voltage to the injector 4 starts), the injector control circuit 24 stops supplying voltage to the solenoid coil of the injector 4.

The storage unit 25 stores (stores) the programs executed by the microcomputer 21. Examples of the storage unit 25 include a read-only memory (ROM) and a random access memory (RAM). The storage unit 25 may be an external storage device connected to the injector control device 2.

In the injector control device 2 according to this embodiment, the charge voltage control circuit 22, the charge voltage detection unit 23, the injector control circuit 24, and the current flow time correction unit 211 may be realized by the microcomputer 21 executing a program stored in the memory unit 25, or may be realized by hardware, or may be realized by a combination of hardware and software.

Next, the charge voltage control circuit 22 of the present embodiment will be further described with reference to the drawings.
FIG. 2 is a graph illustrating an example of a charge voltage when the injector of this embodiment is not energized.
FIG. 3 is a graph illustrating the variations in the charge start threshold and the charge completion threshold.

2, when the charge voltage VCHG of the capacitor becomes equal to or lower than the charge start threshold VL (timing t11), the charge voltage control circuit 22 stores electrical energy in the capacitor based on the voltage supplied from the battery. That is, the charge start threshold VL in this embodiment is the charge voltage VCHG of the capacitor when the charge voltage control circuit 22 starts storing electrical energy in the capacitor. This causes the charge voltage VCHG of the capacitor to rise (timing t11 to timing t12). Next, when the charge voltage VCHG of the capacitor reaches the charge completion threshold VH (timing t12), the charge voltage control circuit 22 stops storing electrical energy in the capacitor. That is, the charge completion threshold VH in this embodiment is the charge voltage VCHG of the capacitor when the charge voltage control circuit 22 stops storing electrical energy in the capacitor, that is, the charge voltage VCHG of the capacitor when charging of the capacitor is completed.

Next, when the injector is not energized, the capacitor naturally discharges (timing t12 to timing t13). In other words, even if the capacitor charge voltage VCHG is not supplied to the injector 4 via the injector control circuit 24, the capacitor charge voltage VCHG naturally decreases over time (timing t12 to timing t13).

When the capacitor charge voltage VCHG again falls below the charge start threshold VL (timing t13), the charge voltage control circuit 22 stores electrical energy in the capacitor based on the voltage supplied from the battery. This causes the capacitor charge voltage VCHG to rise again (timing t13 to timing t14). Next, when the capacitor charge voltage VCHG again reaches the charge completion threshold VH (timing t14), the charge voltage control circuit 22 again stops storing electrical energy in the capacitor.

In this way, when the injector is not energized, the capacitor repeatedly discharges naturally and accumulates electrical energy. The time it takes for the capacitor charge voltage VCHG to drop from the charge completion threshold VH to below the charge start threshold VL is, for example, approximately 2 seconds or more and 4 seconds or less.

Here, in the injector control device 2, there are individual differences in the charge voltage control circuit 22. The individual differences in the charge voltage control circuit 22 are caused by variations in the capacitance component and resistance component of the capacitor in the charge voltage control circuit 22, and variations in the inductance component and resistance component of the coil in the charge voltage control circuit 22. Alternatively, the individual differences in the charge voltage control circuit 22 are caused by the manufacturing tolerance, temperature tolerance, and durability tolerance of each element such as the capacitor and coil in the charge voltage control circuit 22. Note that the factors that cause individual differences in the charge voltage control circuit 22 are not limited to these.

The charge start threshold VL and the charge completion threshold VH vary due to individual differences in the charge voltage control circuit 22. As shown in FIG. 3, in the charge voltage control circuit 22A, the charge start threshold VL is 66.0 V, and the charge completion threshold VH is 67.5 V. In the charge voltage control circuit 22B, the charge start threshold VL is 64.0 V, and the charge completion threshold VH is 66.0 V. In the charge voltage control circuit 22C, the charge start threshold VL is 62.0 V, and the charge completion threshold VH is 64.5 V. In this way, due to individual differences in the charge voltage control circuit 22, the charge start threshold VL varies from about 62.0 V to about 66.0 V. In addition, due to individual differences in the charge voltage control circuit 22, the charge completion threshold VH varies from about 64.5 V to about 67.5 V.

As shown in FIG. 3, in the charge voltage control circuit 22, there is variation in the set of the charge start threshold VL and the charge completion threshold VH. That is, when the charge start threshold VL becomes relatively high, variation occurs in which the charge completion threshold VH also becomes relatively high. On the other hand, when the charge start threshold VL becomes relatively low, variation occurs in which the charge completion threshold VH also becomes relatively low.

As shown in FIG. 3, in each of the charge voltage control circuits 22A, 22B, and 22C, when the injector is not energized, natural discharge of the capacitor occurs repeatedly (timing t22 to timing t23), and electrical energy is repeatedly stored in the capacitor (timing t21 to timing t22 and timing t23 to timing t24).

Here, if there is variation in the charge start threshold VL and the charge completion threshold VH, variation in the fuel injection amount occurs. For example, when a multi-stage injection is performed in which the fuel injection is divided into multiple injections for the purpose of noise reduction, etc., the variation in the fuel injection amount may not be suppressed in the pre-injection in which minute fuel injection is performed. Note that the variation in the fuel injection amount may not be suppressed not only in the case of pre- injection but also in the case of main injection.

In response to this, the current flow time correction unit 211 of the injector control device 2 according to this embodiment acquires the capacitor charge voltage VCHG detected by the charge voltage detection unit 23, and grasps the variation in the charge start threshold VL or the charge completion threshold VH based on the capacitor charge voltage VCHG acquired from the charge voltage detection unit 23. The current flow time correction unit 211 also corrects the current flow time of the injector 4 according to the variation in the charge start threshold VL or the charge completion threshold VH. The injector control circuit 24 then controls the drive of the injector 4 based on the capacitor charge voltage VCHG supplied from the charge voltage control circuit and the current flow time of the injector 4 corrected by the current flow time correction unit 211.

The current flow time correction unit 211 may grasp the variation of at least one of the charge start threshold VL and the charge completion threshold VH based on the charge voltage VCHG of the capacitor obtained from the charge voltage detection unit 23. In other words, the current flow time correction unit 211 may grasp the variation of only the charge start threshold VL, may grasp the variation of only the charge completion threshold VH, or may grasp the variation of both the charge start threshold VL and the charge completion threshold VH based on the charge voltage VCHG of the capacitor obtained from the charge voltage detection unit 23. This also applies to the following description of this embodiment.

The current flow time correction unit 211 may also correct the current flow time of the injector 4 in response to the variation in at least one of the charge start threshold VL and the charge completion threshold VH. That is, the current flow time correction unit 211 may correct the current flow time of the injector 4 in response to the variation in only the charge start threshold VL, may correct the current flow time of the injector 4 in response to the variation in only the charge completion threshold VH, or may correct the current flow time of the injector 4 in response to the variation in both the charge start threshold VL and the charge completion threshold VH. This also applies to the following description of this embodiment.

The operation of the injector control device 2 according to this embodiment will be described in detail below with reference to the drawings.
FIG. 4 is a timing chart illustrating an example of the operation of the injector control device according to the present embodiment.

First, at the start of fuel injection, the injector control circuit 24 supplies the boosted voltage generated by the charge voltage control circuit 22, i.e., the capacitor charge voltage VCHG, to the solenoid coil of the injector 4 (timing t31). At timing t31 shown in FIG. 4, the capacitor charge voltage VCHG has slightly dropped from the charge completion threshold VH due to natural discharge of the capacitor. Next, the current flowing through the solenoid coil of the injector 4 reaches a peak (timing t32). Thus, at the beginning of fuel injection, a peak current flows through the solenoid coil of the injector 4 (timing t32).

At the beginning of fuel injection, the charge voltage supplied to the solenoid coil of the injector 4 is, for example, about 65±3 V. The peak current flowing through the solenoid coil of the injector 4 is, for example, about 14.0±0.35 A.

As shown in FIG. 4, at the beginning of fuel injection, the capacitor charge voltage VCHG is supplied to the solenoid coil of the injector 4 and becomes equal to or lower than the charge start threshold VL. When the current flowing through the solenoid coil of the injector 4 reaches its peak, the charge voltage control circuit 22 starts storing electrical energy in the capacitor based on the voltage supplied from the battery (timing t32). Then, when the capacitor charge voltage VCHG reaches the charge completion threshold VH, the charge voltage control circuit 22 stops storing electrical energy in the capacitor (timing t33).

When the current flowing through the solenoid coil of the injector 4 reaches its peak, the injector control circuit 24 supplies a voltage lower than the charge voltage VCHG supplied at the beginning of the fuel injection, i.e., a voltage supplied from the battery, to the solenoid coil of the injector 4, and holds the needle valve of the injector 4 open (timing t32 to timing t34). The average value of the current (hold current) flowing through the solenoid coil of the injector 4 to hold the needle valve of the injector 4 open is, for example, approximately 3.4 A.

Next, when the energization time set by the energization time correction unit 211 has elapsed since the time when the injector 4 starts to be energized (i.e., the time when the supply of voltage to the solenoid coil of the injector 4 starts: timing t31), the injector control circuit 24 stops the supply of voltage to the solenoid coil of the injector 4 (timing t34). The time from when the injector control circuit 24 starts to energize the injector 4 to when it stops energizing the injector 4 (timing t31 to timing t34) is approximately 0.2 milliseconds or more and 1.5 milliseconds or less.

Next, when several hundred microseconds or several milliseconds have elapsed since the injector control circuit 24 stopped energizing the injector 4, the injector control circuit 24 again supplies the boosted voltage generated by the charge voltage control circuit 22, i.e., the capacitor charge voltage VCHG, to the solenoid coil of the injector 4 (timing t35). The operation of the injector control device 2 from timing t35 to timing t38 is the same as the operation of the injector control device 2 described above with respect to timing t31 to timing t34. The time from when the injector control circuit 24 started energizing the injector 4 to when it stopped energizing the injector 4 (timing t35 to timing t38) is about several milliseconds.

For example, the fuel injection from timing t31 to timing t34 shown in FIG. 4 is an example of a pre-injection of a multi-stage injection. For example, the fuel injection from timing t35 to timing t38 shown in FIG. 4 is an example of a main injection of a multi-stage injection. However, the fuel injection from timing t31 to timing t34 shown in FIG. 4 is not limited to a pre-injection of a multi-stage injection. Also, the fuel injection from timing t35 to timing t38 shown in FIG. 4 is not limited to a main injection of a multi-stage injection.

Here, according to the knowledge obtained by the inventor, the value of the capacitor charge voltage VCHG when the injector 4 starts to be energized, that is, the value of the capacitor charge voltage VCHG at timing t31 and timing t35 shown in FIG. 4, affects the fuel injection amount.

For example, if the value of the capacitor charge voltage VCHG when the injector 4 starts to be energized is relatively high, the current flowing through the solenoid coil of the injector 4 rises relatively quickly from timing t31 to timing t32 and from timing t35 to timing t36. In other words, if the value of the capacitor charge voltage VCHG when the injector 4 starts to be energized is relatively high, the slope of the current flowing through the solenoid coil of the injector 4 (the amount of change in current per unit time, i.e., the rate of change in current) is relatively large from timing t31 to timing t32 and from timing t35 to timing t36. Therefore, if the value of the capacitor charge voltage VCHG when the injector 4 starts to be energized is relatively high, the amount of fuel injected during a certain energization time of the injector 4 is relatively large.

On the other hand, if the value of the capacitor charge voltage VCHG when the injector 4 starts to be energized is relatively low, the rise of the current flowing through the solenoid coil of the injector 4 is relatively slow from timing t31 to timing t32 and from timing t35 to timing t36. In other words, if the value of the capacitor charge voltage VCHG when the injector 4 starts to be energized is relatively low, the slope of the current flowing through the solenoid coil of the injector 4 (the amount of change in current per unit time, i.e., the rate of change in current) is relatively small from timing t31 to timing t32 and from timing t35 to timing t36. Therefore, if the value of the capacitor charge voltage VCHG when the injector 4 starts to be energized is relatively low, the amount of fuel injected during a certain energization time of the injector 4 is relatively small.

As mentioned above, the time during which the value of the capacitor charge voltage VCHG falls from the charge completion threshold VH to the charge start threshold VL due to natural discharge of the capacitor when the injector 4 is not energized (see timing t12 to timing t13 shown in FIG. 2 and timing t22 to timing t23 shown in FIG. 3) is much longer than the energization time of the injector 4 (timing t31 to timing t34 and timing t35 to timing t38) and the time interval between fuel injections (timing t34 to timing t35). Therefore, the variation in the charge start threshold VL or the charge completion threshold VH has a large effect on the value of the capacitor charge voltage when the injector 4 starts to be energized. In other words, as mentioned above with reference to FIG. 3, in the charge voltage control circuit 22, there is a variation in the charge start threshold VL and the charge completion threshold VH as a set. In this way, the variation in the charge completion threshold VH is equal to the variation in the charge start threshold VL, so the variation in the charge start threshold VL also has a large effect on the value of the capacitor charge voltage when the injector starts to be energized.

In response to this, the current flow time correction unit 211 of the injector control device 2 according to this embodiment acquires the capacitor charge voltage VCHG detected by the charge voltage detection unit 23, and grasps the variation in the charge start threshold VL or the charge completion threshold VH based on the capacitor charge voltage VCHG acquired from the charge voltage detection unit 23. In addition, the current flow time correction unit 211 corrects the current flow time of the injector 4 according to the variation in the charge start threshold VL or the charge completion threshold VH.

Specifically, as in the charge voltage control circuit 22A described above with reference to FIG. 3, when the charge start threshold VL or the charge completion threshold VH is relatively high, the current flow time correction unit 211 performs a correction to relatively shorten the current flow time of the injector 4. On the other hand, as in the charge voltage control circuit 22C described above with reference to FIG. 3, when the charge start threshold VL or the charge completion threshold VH is relatively low, the current flow time correction unit 211 performs a correction to relatively lengthen the current flow time of the injector 4.

Then, the injector control circuit 24 controls the driving of the injector 4 based on the capacitor charge voltage VCHG supplied from the charge voltage control circuit and the current conduction time of the injector 4 corrected by the current conduction time correction unit 211.

The injector control device 2 according to this embodiment corrects the energization time of the injector 4 according to the variation in the charge start threshold VL or the charge completion threshold VH, which has a large effect on the value of the capacitor charge voltage VCHG when the injector 4 starts to be energized. This allows the injector control device 2 according to this embodiment to improve the accuracy of correction of the variation in the fuel injection amount.

The memory unit 25 of this embodiment also stores the current flow time of the injector 4 corrected by the current flow time correction unit 211. The injector control circuit 24 then controls the drive of the injector 4 based on the current flow time of the injector 4 corrected by the current flow time correction unit 211 and pre-stored in the memory unit 25. This allows the injector control circuit 24 to control the drive of the injector 4 at a faster processing speed based on the more accurate current flow time of the injector 4.

Next, a specific example of the process in which the current application time correction unit 211 of this embodiment grasps the variation in the charge start threshold VL or the charge completion threshold VH will be described in detail with reference to the drawings.
FIG. 5 is a flowchart showing a specific example of the process executed by the current application time correction unit of the present embodiment.

In this specific example, the current flow time correction unit 211 obtains the capacitor charge voltage VCHG when the injector 4 is not energized from the charge voltage detection unit 23, and grasps the variation in the charge start threshold VL or the charge completion threshold VH by performing statistical processing of the capacitor charge voltage VCHG obtained from the charge voltage detection unit 23. The processing performed by the current flow time correction unit 211 will be described below with reference to the flowchart shown in FIG. 5.

First, in step S11, the charge voltage control circuit 22 stores electrical energy in the capacitor based on the voltage supplied from the battery, and when the charge voltage VCHG of the capacitor reaches the charge completion threshold VH, it stops storing electrical energy in the capacitor. This completes the initial charge.

Next, in step S12, the charge voltage control circuit 22 determines whether the capacitor charge voltage VCHG is equal to or lower than the charge start threshold VL. If the capacitor charge voltage VCHG is not equal to or lower than the charge start threshold VL (step S12: NO), in step S12, the charge voltage control circuit 22 continues to determine whether the capacitor charge voltage VCHG is equal to or lower than the charge start threshold VL.

On the other hand, if the capacitor charge voltage VCHG is equal to or lower than the charge start threshold VL (step S12: YES), in step S13, the charge voltage control circuit 22 stores electrical energy in the capacitor based on the voltage supplied from the battery (charge start).

Next, in step S14, the charge voltage control circuit 22 determines whether the capacitor charge voltage VCHG has reached the charge completion threshold VH. If the capacitor charge voltage VCHG has not reached the charge completion threshold VH, in step S14, the charge voltage control circuit 22 continues to determine whether the capacitor charge voltage VCHG has reached the charge completion threshold VH.

On the other hand, if the capacitor charge voltage VCHG reaches the charge completion threshold VH, in step S15, the charge voltage control circuit 22 stops storing electrical energy in the capacitor (charging stops).

Next, in step S16, the current flow time correction unit 211 obtains the capacitor charge voltage VCHG when the injector 4 is not energized from the charge voltage detection unit 23, and starts logging the capacitor charge voltage VCHG.

Next, in step S17, the charge voltage control circuit 22 determines whether the capacitor charge voltage VCHG is equal to or lower than the charge start threshold VL. Here, in step S16, the current flow time correction unit 211 acquires the capacitor charge voltage VCHG when the injector 4 is not current-carrying from the charge voltage detection unit 23, so in step S17, the charge voltage control circuit 22 determines whether the capacitor charge voltage VCHG has become equal to or lower than the charge start threshold VL due to natural discharge of the capacitor.

If the capacitor charge voltage VCHG is not equal to or less than the charge start threshold VL (step S17: NO), in step S17, the charge voltage control circuit 22 continues to determine whether the capacitor charge voltage VCHG is equal to or less than the charge start threshold VL. On the other hand, if the capacitor charge voltage VCHG is equal to or less than the charge start threshold VL (step S17: YES), in step S18, the current flow time correction unit 211 stops logging the capacitor charge voltage VCHG.

Next, in step S19, the current flow time correction unit 211 determines the variation in the charge start threshold VL or the charge completion threshold VH based on the charge voltage VCHG of the capacitor obtained from the charge voltage detection unit 23, i.e., based on the results of the logging performed in steps S16 to S18. Although not shown in FIG. 5, steps S11 to S18 may be performed multiple times. At this time, the current flow time correction unit 211 determines the variation in the charge start threshold VL or the charge completion threshold VH by performing statistical processing of the charge voltage VCHG of the capacitor obtained from the charge voltage detection unit 23.

For example, the current flow time correction unit 211 obtains from the charge voltage detection unit 23 multiple charge start thresholds VL or charge completion thresholds VH in multiple cycles of charging and discharging the capacitor that occurs when the injector 4 is not energized, and calculates the average value of the multiple charge start thresholds VL or charge completion thresholds VH obtained from the charge voltage detection unit 23 to grasp the variation in the charge start threshold VL or charge completion threshold VH. For example, the current flow time correction unit 211 obtains from the charge voltage detection unit 23 five charge start thresholds VL or charge completion thresholds VH in five cycles of charging and discharging the capacitor that occurs when the injector 4 is not energized, and calculates the average value of the five charge start thresholds VL or charge completion thresholds VH to grasp the variation in the charge start threshold VL or charge completion threshold VH.

Alternatively, for example, the current flow time correction unit 211 obtains from the charge voltage detection unit 23 multiple charge start thresholds VL or charge completion thresholds VH in multiple cycles of charging and discharging the capacitor that occurs when the injector 4 is not energized, and calculates the average value of the remaining multiple charge start thresholds VL or charge completion thresholds VH, excluding the maximum and minimum values, from the multiple charge start thresholds VL or charge completion thresholds VH obtained from the charge voltage detection unit 23, thereby grasping the variation of the charge start threshold VL or charge completion threshold VH. For example, the current flow time correction unit 211 obtains from the charge voltage detection unit 23 five charge start thresholds VL or charge completion thresholds VH in five cycles of charging and discharging the capacitor that occurs when the injector 4 is not energized, and calculates the average value of the remaining three charge start thresholds VL or charge completion thresholds VH, excluding the maximum and minimum values, from the five charge start thresholds VL or charge completion thresholds VH, thereby grasping the variation of the charge start threshold VL or charge completion threshold VH.

Next, in step S19, the current flow time correction unit 211 corrects the current flow time of the injector 4 in accordance with the variation in the charge start threshold VL or the charge completion threshold VH that has been grasped. For example, an example in which the current flow time correction unit 211 corrects the current flow time of the injector 4 in accordance with the variation in the charge start threshold VL or the charge completion threshold VH will be described below.

That is, if the inductance of the solenoid coil of the injector 4 is L and the current flowing through the solenoid coil of the injector 4 at time (t) is I(t), then the following equation is established: I(t) = (V/L) x t. Therefore, the current when the injector 4 is energized is proportional to the voltage. In addition, the equation for the self-induced electromotive force generated in the coil is ΔI/Δt = V/L. Therefore, the energization time correction unit 211 is able to grasp the variation in the charge start threshold VL or the charge completion threshold VH, and calculate the time (t) until the current flowing through the solenoid coil of the injector 4 reaches a target current (e.g., the current for opening the needle valve of the injector 4) for each of the capacitor charge voltages VCHG at the start of energization of the injector 4.

The current flow time correction unit 211 may calculate the absolute value of the current flow time of the injector 4 as the correction value. Alternatively, the current flow time correction unit 211 may calculate a ratio coefficient with respect to a reference value (typ) of the current flow time of the injector 4 as the correction value. The current flow time correction unit 211 then stores the calculated absolute value or ratio coefficient as the correction value in the memory unit 25.

According to this specific example, the current flow time correction unit 211 grasps the variation in the charge start threshold VL or the charge completion threshold VH by performing statistical processing of the capacitor charge voltage VCHG obtained from the charge voltage detection unit 23 when the injector 4 is not energized. This allows the current flow time correction unit 211 to accurately grasp the variation in the charge start threshold VL or the charge completion threshold VH by simple processing when the injector 4 is not driven.

The current flow time correction unit 211 also grasps the variation in the charge start threshold VL or the charge completion threshold VH, for example, by calculating the average value of multiple charge start thresholds VL or charge completion thresholds VH. In this case, the current flow time correction unit 211 can accurately grasp the variation in the charge start threshold VL or the charge completion threshold VH through simple processing, and can further improve the accuracy of correction of the variation in the fuel injection amount.

The current flow time correction unit 211 also grasps the variation in the charge start threshold VL or the charge completion threshold VH by, for example, calculating the average value of the remaining multiple charge start thresholds VL or the charge completion thresholds VH excluding the maximum and minimum values of the charge start threshold VL or the multiple charge completion thresholds VH. In this case, the current flow time correction unit 211 can accurately grasp the variation in the charge start threshold VL or the charge completion threshold VH through simple processing, and can further improve the correction accuracy of the variation in the fuel injection amount.

The injector control circuit 24 also controls the driving of the injector 4 based on at least one of the absolute value of the current flow time of the injector 4 calculated by the current flow time correction unit 211 and the ratio coefficient relative to the reference value (typ) of the current flow time of the injector 4, which are pre-stored in the memory unit 25. Therefore, the injector control circuit 24 can control the driving of the injector 4 at a faster processing speed based on the more accurate current flow time of the injector 4.

The current flow time correction unit 211 can execute the process of the specific example described with reference to FIG. 5 during the production process of the injector control device 2. That is, the current flow time correction unit 211 can correct the current flow time of the injector 4 during the production process. The memory unit 25 can store the current flow time of the injector 4 corrected by the current flow time correction unit 211 during the production process. As a result, even when the electronic control device (ECU) is replaced, the injector control device 2 that functions as part of the replaced electronic control device can improve the correction accuracy of the variation in the fuel injection amount. Therefore, the electronic control device can be easily replaced in the market after the injector control device 2 according to this embodiment is shipped from the factory.

The current flow time correction unit 211 can execute the process of the specific example described with reference to FIG. 5 in the market after the injector control device 2 is shipped from the factory. That is, the current flow time correction unit 211 can correct the current flow time of the injector 4 in the market after it is shipped from the factory. The memory unit 25 can store the current flow time of the injector 4 corrected in the market by the current flow time correction unit 211. As a result, even if the charge start threshold VL or the charge completion threshold VH changes in the market due to, for example, deterioration of the capacitor over time, the injector control device 2 according to this embodiment can improve the correction accuracy of the variation in the fuel injection amount.

The above describes an embodiment of the present invention. However, the present invention is not limited to the above embodiment, and various modifications can be made without departing from the scope of the claims. The configurations of the above embodiment can be partially omitted or arbitrarily combined in a different way than described above.

2: Injector control device, 3: Engine operation information, 4: Injector, 21: Microcomputer, 22, 22A, 22B, 22C: Charge voltage control circuit, 23: Charge voltage detection unit, 24: Injector control circuit, 25: Storage unit, 211: Current application time correction unit, VCHG: Charge voltage, VH: Charge completion threshold, VL: Charge start threshold

Claims (6)

An injector control device that controls the driving of an injector that injects fuel,
a charge voltage control circuit that stores electrical energy in the capacitor based on a voltage supplied from the battery when a charge voltage of the capacitor becomes equal to or lower than a charge start threshold, and stops storing the electrical energy when the charge voltage reaches a charge completion threshold;
A charge voltage detection unit that detects the charge voltage;
a current application time correction unit that obtains from the charge voltage detection unit the charge voltage when the injector is not current-applied, logs the charge voltage obtained from the charge voltage detection unit from when the charge voltage reaches the charge completion threshold until the charge voltage becomes equal to or lower than the charge start threshold due to natural discharge of the capacitor, grasps a variation in the charge start threshold or the charge completion threshold based on a result of the logging, and corrects a current application time of the injector in accordance with the variation;
an injector control circuit that controls driving of the injector based on the charge voltage supplied from the charge voltage control circuit and the current conduction time corrected by the current conduction time correction unit;
Equipped with
the current flow time correction unit performs a correction to make the current flow time shorter than a second reference value that is preset as a value of the current flow time when the charge start threshold or the charge completion threshold acquired from the charge voltage detection unit as the result of the logging is higher than a first reference value that is preset as a value within the range of variation that exists due to individual differences in the charge voltage control circuit, and performs a correction to make the current flow time longer than the second reference value when the charge start threshold or the charge completion threshold acquired from the charge voltage detection unit as the result of the logging is lower than the first reference value . 2. The injector control device according to claim 1, wherein when the current application time correction unit grasps the variation in the charge start threshold or the charge completion threshold based on the result of the logging, the current application time correction unit calculates an average value of the multiple charge start thresholds or the multiple charge completion thresholds acquired from the charge voltage detection unit as the result of the multiple logging operations. 2. The injector control device according to claim 1, wherein , when the current application time correction unit grasps the variation in the charge start threshold or the charge completion threshold based on the result of the logging, the current application time correction unit calculates an average value of the remaining multiple charge start thresholds or the charge completion thresholds excluding a maximum value and a minimum value from among the multiple charge start thresholds or the charge completion thresholds acquired from the charge voltage detection unit as the multiple results of the logging. a storage unit that stores the current conduction time corrected by the current conduction time correction unit,
4. The injector control device according to claim 1 , wherein the injector control circuit controls driving of the injector based on the current supply time corrected by the current supply time correction unit and stored in the storage unit. The power-on time correction unit corrects the power-on time in a production process,
5. The injector control device according to claim 4 , wherein the memory unit stores the current supply time corrected by the current supply time correction unit during the production process. The power-on time correction unit corrects the power-on time in a market after being shipped from a factory,
5. The injector control device according to claim 4 , wherein the storage unit stores the current supply time corrected by the current supply time correction unit in the market.

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