JP7413928B2 - Internal combustion engine fuel injection control device - Google Patents

Description

The disclosure in this specification relates to a fuel injection control device for an internal combustion engine.

In this type of fuel injection control device, the nozzle hole is opened by lifting the valve body as the fuel injection device is energized, and fuel injection is performed. Further, as a fuel injection device, a so-called flying needle structure fuel injection device is known, which performs fuel injection with a valve body in an intermediate lift state. In this fuel injection device, by not bringing the valve body into contact with the upper limit stopper, it is possible to reduce the variation in injection amount due to bounce of the valve body and the variation in injection amount due to variation in the upper limit stopper position due to individual differences and changes over time. You can get benefits such as:

Furthermore, in Patent Document 1, in one injection opportunity, energization and de-energization are performed multiple times with the valve body in an intermediate lift state, thereby suppressing the enlargement of the fuel injection device and injecting a large amount of fuel. The technology that makes fuel injection possible is described. In this case, after the first energization is cut off, the second energization is started before the valve body reaches the valve closing position, so that fuel injection is continued through the first energization and the second energization. ing.

US Patent Application Publication No. 2020/0063694

However, with the technology of Patent Document 1, an error may occur in the fuel injection amount when energization and de-energization are performed multiple times with the valve body in an intermediate lift state in one injection opportunity. . Therefore, it is thought that there is room for technical improvement.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a fuel injection control device for an internal combustion engine that can appropriately perform fuel injection control.

The fuel injection control device for an internal combustion engine according to the present invention includes:
It has a drive part that is driven by energization, and a valve body that opens an injection hole according to the drive of the drive part, and the injection amount is changed according to the energization time of the drive part, and the valve body is lifted. Applied to a fuel injection system equipped with a fuel injection device that achieves a maximum injection rate by achieving an intermediate lift state where the amount becomes a predetermined intermediate lift amount,
A fuel injection control device that determines an energization time according to the injection amount using injection characteristic data indicating a relationship between the energization time and the injection amount, and energizes the drive unit according to the energization time,
The number of times the drive unit is energized in one injection opportunity is determined, and the energization time of each stage is determined so that fuel injection at the maximum injection rate in the intermediate lift state is performed during the injection period during which energization is performed. a time setting unit that sets an interval time between each of the energizations;
an energization control section that energizes the drive section based on the energization time of each stage and the interval time set by the time setting section;
When carrying out one-stage energization in which at least one stage of energization is performed and two-stage energization in which two stages of energization are performed in one injection opportunity, the actual injection amount that is the actual injection amount in each of these energizations is obtained. An injection amount acquisition unit;
a characteristic adjustment section that calculates an adjustment amount of the injection characteristic data based on the actual injection amount in each energization acquired by the injection amount acquisition section;
Equipped with
The time setting section sets the energization time using the adjustment amount calculated by the characteristic adjustment section.

In the fuel injection system configured as described above, in the fuel injection device, the drive section is driven by energization, and the nozzle hole is opened by the lift of the valve body accompanying the drive of the drive section to perform fuel injection. In this case, the injection amount changes depending on the energization time of the drive unit, and the maximum injection rate is achieved by placing the valve body in an intermediate lift state. In fuel injection systems with a so-called flying needle structure, in which fuel is injected with the valve body in an intermediate lift state, the valve body does not come into contact with the upper limit stopper, which provides benefits such as reducing the variation in injection amount caused by bounce of the valve body. It will be done.

Further, in the above configuration, the number of times the drive unit is energized in one injection opportunity is determined, and the fuel injection at the maximum injection rate in the intermediate lift state is performed at each stage during the injection period during which the energization is performed. The energization time and the interval time between each energization can be set. Furthermore, the drive unit is energized based on the energization time and interval time of each stage. In this case, by repeatedly increasing and decreasing the valve body lift amount through multiple divided energizations for one fuel injection, the valve body is maintained in the desired intermediate lift state without expanding the intermediate lift region of the fuel injection device. can do. Further, in energizing each stage, injection can be continuously performed at the maximum injection rate, linearity can be given to the fuel injection amount, and highly accurate fuel injection can be performed.

Here, when performing fuel injection by multiple stages of energization in one injection opportunity, it is desirable that the linearity of the fuel injection amount with respect to the energization time be maintained regardless of the number of energization stages. In this regard, when performing at least one-stage energization and two-stage energization in one injection opportunity, the actual injection amount that is the actual injection amount in each energization is obtained, and the actual injection amount in each energization is obtained. Based on this, the adjustment amount of the injection characteristic data is calculated. Then, when the adjustment amount of the injection characteristic data is calculated, the energization time is set using the adjustment amount. Thereby, even if the number of energization stages in one injection opportunity is changed, fuel injection can be appropriately performed at each of the energization stages. As a result, fuel injection control can be performed appropriately.

FIG. 1 is a configuration diagram showing an overview of a fuel injection system. FIG. 3 is a sectional view showing the internal structure of the fuel injection device. A time chart showing a series of fuel injection processes. (a) is a diagram showing the relationship between fuel pressure and energization time, and (b) is a diagram showing the relationship between fuel pressure and interval time. A time chart for explaining the outline of settings of energization time and interval time. A diagram showing the relationship between fuel pressure and correction value C. 5 is a flowchart showing a processing procedure for fuel injection control. A diagram showing the relationship between fuel pressure and each threshold value Th1 to Th3. The figure which shows the relationship between energization time and injection amount. The figure which shows the relationship between energization time and injection amount. A time chart for explaining characteristic adjustment injection at each adjustment point. A time chart showing changes in the lift amount of the nozzle needle. 5 is a flowchart showing the procedure of characteristic adjustment processing.

Hereinafter, embodiments will be described with reference to the drawings. The present embodiment embodies a fuel injection control device that controls fuel injection by a fuel injection device in a common rail fuel injection system (accumulation fuel injection system) that controls, for example, an on-vehicle diesel engine.

In FIG. 1, a four-cylinder diesel engine (hereinafter referred to as engine 10) serving as an internal combustion engine is provided with a fuel injection device 11 for each cylinder, and these fuel injection devices 11 are connected to a common rail 12 (pressure accumulation pipe) common to each cylinder. It is connected. A high-pressure pump 13 as a fuel pump is connected to the common rail 12, and as the high-pressure pump 13 is driven, the pressure of the fuel is increased, and high-pressure fuel equivalent to the injection pressure is continuously accumulated in the common rail 12. The high-pressure pump 13 is driven as the engine 10 rotates, and repeatedly sucks and discharges fuel in synchronization with the engine rotation. The high-pressure pump 13 is provided with an electromagnetically driven suction metering valve (SCV) 13a in its fuel suction section, and the low-pressure fuel pumped up from the fuel tank 15 by the feed pump 14 is passed through the suction metering valve 13a. and is sucked into the fuel chamber of the high-pressure pump 13.

The common rail 12 is provided with a pressure sensor 16 that detects fuel pressure (fuel pressure) within the common rail 12 as the pressure of fuel supplied to the fuel injection device 11. Note that the pressure sensor 16 may be provided in each fuel injection device 11 at any position between the fuel outlet of the common rail 12 and the nozzle hole 33 of the fuel injection device 11 (see FIG. 2). Specifically, in each fuel injection device 11, a pressure sensor 16 may be provided in a high-pressure fuel passage through which high-pressure fuel flows.

The ECU 20 is an electronic control unit equipped with a well-known microcomputer 21 (microcomputer) consisting of a CPU and various memories (RAM, ROM, etc.), and performs various controls based on control programs stored in the ROM. In addition to the detection signals from the pressure sensor 16 described above, the microcomputer 21 receives detection signals from various sensors such as a rotation speed sensor that detects the engine rotation speed, an accelerator opening sensor that detects the accelerator opening, and a vehicle speed sensor that detects the vehicle speed. Signals are input sequentially. Then, the microcomputer 21 determines the fuel injection amount and injection timing as the fuel injection mode based on engine operation information such as the engine rotation speed and the accelerator opening, and controls the fuel injection by the fuel injection device 11 accordingly. Through such fuel injection control, fuel injection from the fuel injection device 11 to the combustion chamber in each cylinder is controlled.

In the ECU 20, the microcomputer 21 generates an energization pulse as an energization command signal, and outputs the energization pulse to the drive circuit 22. As is well known, the drive circuit 22 has a high-voltage power source and a low-voltage power source, and at the beginning of energization with the rise of the energization pulse, the drive circuit 22 is configured to open the fuel injection device 11 at high speed. The fuel injection device 11 is maintained in an open state by applying a high voltage to the drive unit (an electric actuator 60 described later) and then switching the applied voltage from the high voltage to the low voltage.

Further, the ECU 20 sets a target value for the fuel pressure in the common rail 12 based on the engine operating information, and also matches the actual fuel pressure with the target fuel pressure based on the deviation between the target fuel pressure and the actual fuel pressure (actual fuel pressure). Feedback control is implemented to ensure that

Here, the structure of the fuel injection device 11 will be explained with reference to FIG. 2. Note that in FIG. 2, the vertical direction indicates the axial direction of the fuel injection device 11, and the lower side of the figure is the tip side of the fuel injection device 11.

In the fuel injection device 11, a fixed plate 40 is integrally provided inside the body 31, and a nozzle needle 32 as a valve body is housed in a reciprocating state on the distal side of the fixed plate 40. ing. A plurality of nozzle holes 33 are formed at the tip of the body 31. When the tip of the nozzle needle 32 comes into contact with the seat portion 31a of the body 31, the nozzle hole 33 is closed and fuel injection is stopped. Moreover, when the tip of the nozzle needle 32 separates from the seat portion 31a, the nozzle hole 33 is opened and fuel injection is performed.

A high pressure passage 34 is formed in the body 31 and the fixed plate 40 so as to pass through the fixed plate 40. The high-pressure passage 34 is provided in a range extending from the peripheral portion of the nozzle needle 32 to the tip of the fuel injection device 11, that is, to the nozzle hole 33, and is supplied from the common rail 12 through this high-pressure passage 34. High-pressure fuel is guided to the nozzle hole 33.

A cylindrical cylinder 35 is attached to the front end surface (lower end surface in the figure) of the fixed plate 40, and the upper end of the nozzle needle 32 is slidably inserted into the cylinder 35. The nozzle needle 32 is biased in the valve-closing direction by a spring 36 provided at the tip side of the cylinder 35. A pressure control chamber 37 is provided within the cylinder 35 above the nozzle needle 32 . The pressure control chamber 37 can be filled with high-pressure fuel, and when the pressure control chamber 37 is filled with high-pressure fuel, the nozzle needle 32 is maintained in a closed state by the high-pressure fuel. ing.

The fixed plate 40 is formed with an inflow passage 41 through which high-pressure fuel flows into the pressure control chamber 37 and an outflow passage 42 through which fuel flows out from the pressure control chamber 37. The inflow passage 41 is provided to be branched from the high pressure passage 34, and an orifice for restricting the fuel flow rate is formed in its downstream portion (that is, the portion communicating with the pressure control chamber 37). Further, an orifice is formed in a downstream portion of the outflow passage 42 (that is, a portion communicating with a low pressure chamber 64 described later) to limit the fuel flow rate.

A disk-shaped movable plate 50 is arranged within the pressure control chamber 37 . The movable plate 50 is arranged to face the lower end surface of the fixed plate 40 and is movable in the pressure control chamber 37 in the vertical direction in the figure. A communication passage 51 is formed in the movable plate 50 to communicate the outflow passage 42 and the pressure control chamber 37. An orifice is formed in the downstream portion of the communication passage 51 to limit the fuel flow rate. The movable plate 50 closes the outlet portion of the inflow passage 41 while in contact with the fixed plate 40, but maintains communication between the pressure control chamber 37 and the outflow passage 42 through the orifice of the communication passage 51. ing. A spring 38 that presses the movable plate 50 against the fixed plate 40 is provided in the pressure control chamber 37 .

Since the outer diameter of the movable plate 50 is smaller than the inner diameter of the cylinder 35, a gap is formed between the outer circumferential surface of the movable plate 50 and the inner circumferential surface of the cylinder 35. Therefore, when the movable plate 50 is separated from the fixed plate 40, the high-pressure fuel in the inflow passage 41 flows into the pressure control chamber 37 (specifically, the upper surface side of the nozzle needle 32) through the gap on the outer periphery of the movable plate 50. do.

Further, an electric actuator 60 as a drive unit is housed inside the body 31 on the side opposite to the tip end of the fixed plate 40. The electric actuator 60 includes a solenoid coil 61, a control valve 62 as a valve member, and a spring 63 as a biasing member. The control valve 62 is movable in the vertical direction in the figure within the low pressure chamber 64. When the solenoid coil 61 is de-energized, the control valve 62 is held pressed against the fixed plate 40 by the biasing force of the spring 63, and the fuel injection device 11 is held in the closed state.

Further, when the solenoid coil 61 is energized, the control valve 62 is separated from the fixed plate 40 against the urging force of the spring 63. Then, due to the movement of the control valve 62, the high pressure fuel in the pressure control chamber 37 flows out into the low pressure chamber 64 via the outflow passage 42 of the fixed plate 40 and the communication passage 51 of the movable plate 50, and the nozzle needle 32 accordingly flows out. Move to the valve opening side. As a result, the nozzle hole 33 becomes open, and fuel injection is started. At this time, the nozzle needle 32 is lifted from the valve-closed position, so that the injection rate (that is, the injection amount per unit time) gradually increases. When the needle lift amount reaches a predetermined lift amount at which the opening area of the seat portion 31a (that is, the gap area between the seat portion 31a and the nozzle needle 32) and the total cross-sectional area of the nozzle hole 33 become equal, the injection rate is maximized. After the injection rate is reached and the needle lift amount reaches the predetermined lift amount, the state of the maximum injection rate is maintained.

In the fuel injection device 11 of this embodiment, when the needle lift amount reaches the predetermined lift amount at which the maximum injection rate is achieved, the nozzle needle 32 does not hit the upper limit stopper (for example, the movable plate 50) on the valve opening side. , fuel injection is performed in an intermediate lift state (floating state). The fuel injection device 11 has a so-called flying needle structure that reaches a maximum injection rate when the needle lift amount reaches a predetermined intermediate lift amount and realizes fuel injection in that state.

Then, when the solenoid coil 61 is de-energized and the control valve 62 comes into contact with the fixed plate 40 due to the biasing force of the spring 63, the outflow passage 42 is closed, and in this state, the movable plate 50 is moved by the high pressure fuel from the inflow passage 41. is pushed down. As a result, high-pressure fuel flows into the pressure control chamber 37, the nozzle needle 32 is pushed down to the valve closing side, and the nozzle hole 33 returns to the closed state.

Note that in the electric actuator 60, it is also possible to use a driving section including a piezo element. That is, it is also possible to use a piezo-driven fuel injection device as the fuel injection device 11.

In a configuration in which fuel is injected using a fuel injection device 11 with a flying needle structure, the nozzle needle 32 is not brought into contact with the upper limit stopper, thereby reducing injection amount variations due to bounce of the nozzle needle 32, individual differences, and changes over time. This provides the advantage of being able to reduce variations in injection amount due to variations in the upper limit stopper position. However, on the other hand, there is a concern that there will be a limit to the amount of fuel that can be injected at one injection opportunity. In this case, the injection period is limited due to the constraint that does not allow the nozzle needle 32 to reach the upper limit stopper, but if you try to lengthen the injection period, it is necessary to expand the lift region from the valve closing position to the upper limit stopper. , there is a concern that the fuel injection device 11 may become larger.

Therefore, in this embodiment, the number of times of energization of the fuel injection device 11 in one injection opportunity is determined, and during the injection period in which the energization is performed, fuel injection is performed at the maximum injection rate in the intermediate lift state. The energization time Tq of each stage and the interval time TINT between each energization are set. Then, the electric actuator 60 is energized based on the set energization time Tq of each stage and the interval time TINT.

FIG. 3 is a time chart for explaining the behavior when the nozzle needle 32 of the fuel injection device 11 is lifted at an intermediate lift amount before reaching the lift upper limit Lmax, and fuel injection is performed in that state. . FIG. 3 shows the behavior when the fuel injection device 11 is energized during the energization period of the two stages before and after, and one fuel injection is performed by energizing the two stages before and after. Here, the energization time by the first stage energization pulse is Tq1, the energization time by the second stage energization pulse is Tq2, and the interval time between the first and second stage energization pulses is TINT.

In FIG. 3, at timing t1, the first-stage energization pulse is raised, and fuel injection is started with the start of energization. At this time, at the beginning of the energization, a high current is applied by applying a high voltage to the solenoid coil 61 in order to open the nozzle needle 32 of the fuel injection device 11 at high speed, and then the applied voltage is changed to a high voltage. By switching from to a low voltage, a holding current is applied to maintain the nozzle needle 32 in an open state.

After the start of energization at timing t1, the lift amount of the nozzle needle 32 (needle lift amount) gradually increases. At this time, the needle lift amount increases in proportion to the duration of energization. Further, as the nozzle needle 32 is lifted, the injection rate increases. Then, at timing t2, the needle lift amount reaches a predetermined lift amount at which the opening area of the seat portion 31a and the total cross-sectional area of the injection holes 33 become equal, and the injection rate becomes the maximum injection rate. In FIG. 3, the needle lift amount at which the injection rate becomes the maximum injection rate (that is, the needle lift amount at which the opening area of the seat portion 31a and the total cross-sectional area of the nozzle holes 33 become equal) is set as the lift lower limit Lmin. After timing t2, the maximum injection rate is maintained.

At timing t3 when a predetermined energization time Tq1 has elapsed from the start of energization, energization is temporarily stopped as the energization pulse falls. As a result, the needle lift amount changes from increasing to decreasing. At this time, the needle lift amount changes from rising to falling without reaching the lift upper limit Lmax of the fuel injection device 11.

After timing t3, the needle lift amount decreases in proportion to the duration of the energization stop. However, in this case, since the needle lift amount is larger than the lift lower limit Lmin, the maximum injection rate is maintained even after the first stage energization is stopped. That is, the range from the lower limit Lmin of lift to the upper limit Lmax of lift is the intermediate lift region Rf, and when the needle lift amount is within the intermediate lift region Rf, the maximum injection rate is maintained.

Thereafter, at timing t4 when a predetermined interval time TINT has elapsed since the energization was stopped, the second stage energization pulse is started, and the needle lift amount changes to increase again. At this time, at timing t4, the energization of the solenoid coil 61 is restarted before the needle lift amount reaches the lift lower limit Lmin. During the second stage of energization, similarly to the first stage of energization, application of high voltage at the beginning of energization and subsequent switching to application of low voltage are performed. After the energization is resumed at timing t4, the needle lift amount increases again in proportion to the duration of energization, and the maximum injection rate is maintained as it is.

At timing t5, when a predetermined energization time Tq2 has elapsed from the start of the second stage energization, the energization is stopped as the energization pulse falls, and the needle lift amount changes from an increase to a decrease. Thereafter, the needle lift amount falls below the lift lower limit Lmin at timing t6, and further becomes zero at timing t7. This completes one fuel injection.

During the above-mentioned one-time fuel injection, after fuel injection starts with the start of energization of the first stage and the injection rate reaches the maximum injection rate, until the injection rate starts to decrease with the end of energization of the second stage. During the period (period t2 to t6), the needle lift amount is maintained within the intermediate lift region Rf of Lmin to Lmax, and as a result, the injection rate is maintained at the maximum injection rate during the same period. Thereby, in the fuel injection device 11, it is possible to extend the injection period while maintaining the intermediate lift state of the nozzle needle 32, and it is possible to increase the amount of fuel injection to a desired amount.

Although not shown in the drawings, it is also possible to perform one fuel injection by energizing in three stages, front and rear, or in more stages. In this case, as described above, it is sufficient that the needle lift amount is maintained within the intermediate lift region Rf during energization at each stage, and as a result, fuel injection is continuously performed at the maximum injection rate.

Next, in fuel injection control that realizes one fuel injection by multistage energization, specific processing contents for setting the energization time Tq and interval time TINT of each stage will be explained. Here, an example will be described in a three-stage energization mode in which one fuel injection is achieved by three stages of energization.

Prior to setting the energization time Tq and interval time TINT for each stage, the ECU 20 determines the required injection amount Qr for the current fuel injection and the energization time Tr (total energization time) of the fuel injection device 11 corresponding to the required injection amount Qr. Calculate. The required injection amount Qr is the total injection amount for one combustion. However, when a main injection and a pre-injection preceding the main injection are performed in one combustion stroke, the required injection amount Qr to be divided may be the injection amount in the main injection. As is well known, the required injection amount Qr is calculated based on engine operating conditions such as engine speed and load, and fuel pressure (rail pressure), and the energization time Tr is calculated based on the required injection amount Qr according to the engine speed. Calculated by converting it into hours.

Then, when the required injection amount Qr (or energization time Tr) is greater than or equal to a predetermined value, the ECU 20 performs multistage divided energization, and sets the energization time Tq and interval time TINT for each stage. For example, when performing divided energization in three stages, energization times Tq1, Tq2, and Tq3 for the first to third stages and interval times TINT1 and TINT2 are set.

The first stage energization time Tq1 is set as the energization time from the start of the first energization until the needle lift amount reaches a predetermined lift amount in the intermediate lift region Rf (Lmin to Lmax). In other words, the first stage energization time Tq1 is set as the energization time required for the needle to lift up from the zero lift position (valve closed position) to a predetermined position near the lift upper limit Lmax.

Further, the energization times Tq2 and Tq3 of the second and third stages are both set as energization times that enable an upward change in the needle lift amount in the intermediate lift region Rf. More specifically, the second stage energization time Tq2 is set as the energization time required for the needle to lift up from a predetermined position at or near the lower lift limit Lmin to a predetermined position near the upper lift limit Lmax in the intermediate lift region Rf. The third stage energization time Tq3 is the time required to energize the final stage in the current fuel injection, and is set as the remaining energization time after the first stage energization and the second stage energization.

The energization time Tq of each stage is set as a time during which the needle lift position does not reach the lift upper limit Lmax after the start of energization of each stage. In this case, by increasing the number of energization stages, the amount of injection that can be injected at one time can be increased while maintaining a state in which the nozzle needle 32 does not reach the upper limit stopper.

The lift-up speed (valve opening speed) of the nozzle needle 32 changes depending on the fuel pressure. Therefore, it is desirable that the energization times Tq1 to Tq3 of each stage be set according to the fuel pressure. For example, the energization times Tq1 to Tq3 of each stage may be set using the relationship shown in FIG. 4(a). FIG. 4(a) shows a relationship between the energization times Tq1 to Tq3 of each stage in which the higher the fuel pressure, the shorter the energization time. When the first stage is energized, the nozzle needle 32 is lifted from the zero lift position (valve closed position), so taking this into account, the energization time Tq1 of the first stage is changed to the energization time Tq2 of the second and third stages, It is defined as a longer time than Tq3.

Further, the interval times TINT1 and TINT2 between the energizations of each stage are both set as energization stop times that enable a downward change in the needle lift amount in the intermediate lift region Rf. More specifically, each of the interval times TINT1 and TINT2 is set as the energization stop time required for the needle to lift down from a predetermined position near the lift upper limit Lmax to a predetermined position at or near the lift lower limit Lmin in the intermediate lift region Rf.

Each interval time TINT is set as a time during which the needle lift position does not fall below the lift lower limit Lmin after the energization of each stage is stopped. In this case, in the intermediate lift region Rf (Lmin to Lmax), the amount of fuel ejected from the nozzle hole 33 per time is constant, so the closing speed of the nozzle needle 32 during the energization suspension period is constant. Therefore, if the needle lift amount at the time of energization is stopped is L1, and the needle valve closing speed is Vnc, the interval time TINT may be determined as a time that satisfies the following equation (1).
TINT=(L1-Lmin)/Vnc...(1)
In this case, if the needle lift position at the time of stopping energization in the former stage and the needle lift position at the start of energization in the latter stage are constant, the interval time TINT is set as a constant value.

Note that if the interval time TINT is too long, the needle lift position falls below the lift lower limit Lmin. In this case, the flow rate restriction of the seat portion 31a in the fuel injection device 11 causes the injection rate to be lower than the maximum injection rate, and the control linearity of the fuel injection amount with respect to the energization time is impaired. In this regard, by determining the interval time TINT as the longest time determined by the above equation (1) or less than that time, it is possible to maintain the control linearity of the fuel injection amount with respect to the energization time.

The lift-down speed (valve closing speed) of the nozzle needle 32 changes depending on the fuel pressure. Therefore, it is desirable that each interval time TINT1, TINT2 be set according to the fuel pressure. For example, each interval time TINT1, TINT2 may be set using the relationship shown in FIG. 4(b). FIG. 4B shows a relationship in which the higher the fuel pressure is, the shorter the energization stop time is for each interval time TINT1 and TINT2.

It is preferable that the energization time Tr (total energization time) and the energization times Tq1, Tq2, and Tq3 of each stage have a relationship expressed by the following equation (2).
Tr=Tq1+Tq2+Tq3...(2)
In this case, as described above, the first stage energization time Tq1 is set as the energization time required for the needle lift from the zero lift position (valve closed position) to a predetermined position near the lift upper limit Lmax, and the second stage energization time Tq2 is set as the energization time required to lift the needle from a predetermined position near the lift lower limit Lmin to a predetermined position near the lift upper limit Lmax. The third stage energization time Tq3 is set from the following equation (3).
Tq3=Tr-(Tq1+Tq2)...(3)
Next, a supplementary explanation will be given regarding the settings of the energization times Tq1 to Tq3 of each stage.

Figure 5 shows a 1-stage energization mode in which one fuel injection is performed in one stage of energization, and a 3-stage energization mode in which one fuel injection is performed in three stages of divided energization when injecting fuel with the same injection amount. 3 is a time chart showing the mode of energization in each stage energization mode. In FIG. 5, the change in needle lift amount in the one-step energization mode is shown by a dashed line, and the change in the needle lift amount in the three-step energization mode is shown by a solid line. In the first-stage energization mode, fuel injection corresponding to the required injection amount is performed with one energization during the energization time Tr. In the 1-stage energization mode, as in the 3-stage energization mode, the injection rate reaches the maximum injection rate in the region where the needle lift amount is larger than the lift lower limit Lmin, and the nozzle needle 32 does not reach the upper limit stopper and the flying needle It is assumed that fuel injection will be performed under the following conditions. Note that the lift upper limit Lmax shown in FIG. 5 is the lift upper limit position when performing multi-stage divided energization, and it is assumed that the lift upper limit when performing single-stage energization is on the higher lift side than the Lmax position. .

First, the single-stage energization mode will be explained. When performing one-step energization, energization is performed continuously during the period from the start of energization until the energization time Tr elapses. In this case, from timing t11, which is the energization start timing, the needle lift amount increases approximately in proportion to time, and after the energization is stopped, the needle lift amount decreases approximately in proportion to time. The injection rate starts to increase at timing t1, is maintained at the maximum injection rate during the period from timing t12 to t13, and then becomes zero at timing t14.

On the other hand, when performing three-stage energization in the three-stage energization mode, three energizations and two energization pauses are performed alternately. In this case, after timing t11, which is the energization start timing, by repeating energization and energization stop, an increase in the needle lift amount that is approximately proportional to time and a decrease in the needle lift amount that is approximately proportional to time occur alternately.

Here, the period from timing tx1 when the first stage energization ends in the three-stage energization mode to timing tx2 when the third stage energization ends is defined as a period TD, and for that period TD, in the first stage energization mode, The energization in the 3-stage energization mode is compared with the energization in the three-stage energization mode.

In this case, "TD1" of the period TD is a period corresponding to the energization period (lift-up period) in the 1st stage energization mode, which is the energization time Tq2 of the 2nd stage and the energization time Tq3 of the 3rd stage. This period corresponds to the sum of the above. Moreover, "TD2" of the period TD is a period corresponding to the energization suspension period (lift-down period) in the first-stage energization mode, and this is a period that corresponds to the first interval time TINT1 and the second interval time TINT2. It corresponds to the added period.

According to this relationship, in both the one-stage energization mode and the three-stage energization mode, the end timing tx2 of the period TD is determined by the energization times Tq1, Tq2, Tq3 for three stages, and the interval time TINT1, TINT1, for two stages. This is the timing when the energization suspension by TINT2 has been completed. Therefore, at the end timing tx2, the needle lift amount (lift position of the nozzle needle 32) becomes the same in each of the 1-stage energization mode and the 3-stage energization mode, and then at the timing t13 when the injection rate becomes lower than the maximum injection rate, the needle lift The timing t14 at which the amount becomes zero is also the same in the one-stage energization mode and the three-stage energization mode.

From the above, the relationship between the energization time Tr (total energization time) and the energization times Tq1, Tq2, and Tq3 of each stage is defined as the above equation (2).

Furthermore, during actual operation of the fuel injection device 11, there may be a delay in the response of the nozzle needle 32 when the nozzle needle 32 changes from lift-down to lift-up at the start of energization in the second and subsequent stages. It is desirable to set the energization time Tq and interval time TINT of each stage in consideration of response delay. In this case, it is preferable that the third stage energization time Tq3 is set using the correction value C for the response delay according to the following equation (4).
Tq3=Tr-(Tq1+Tq2)+C...(4)
By correcting the response delay as described above, the linearity of the injection amount response to the energization time Tq is maintained. Note that the correction value C is preferably determined based on the fuel pressure using the relationship shown in FIG.

As a correction for the response delay of the nozzle needle 32, instead of correcting the energization time Tq of the second and subsequent stages, the configuration may be such that the interval time TINT is corrected. In this case, the interval time TINT may be corrected by taking into consideration the response delay.

FIG. 7 is a flowchart showing a procedure for fuel injection control performed by energizing the fuel injection device 11, and this process is repeatedly performed by the microcomputer 21 of the ECU 20 at predetermined intervals.

In FIG. 7, in step S11, the required injection amount Qr is calculated based on engine operating conditions such as engine speed and load, and fuel pressure (rail pressure). In the subsequent step S12, the required injection amount Qr is converted into time according to the engine rotation speed to calculate the energization time Tr. At this time, the energization time Tr is calculated based on the required injection amount Qr using injection characteristic data indicating the relationship between the energization time and the injection amount.

Thereafter, in step S13, it is determined whether the required injection amount Qr is less than a predetermined threshold Th1. The threshold value Th1 is a threshold value for switching whether to perform the current fuel injection in a single-stage energization mode or in a multi-stage energization mode of two or more stages. Note that in step S13, it is also possible to use the energization time Tr instead of the required injection amount Qr as the determination parameter.

If the required injection amount Qr is less than the threshold Th1, the process advances to step S14. In step S14, it is determined that fuel injection will be performed in the first stage energization mode this time. Then, in the subsequent step S15, an energization pulse for one stage energization is generated based on the energization time Tr calculated in the step S12, and in the subsequent step S16, the energization pulse is output. In this case, a one-stage energization pulse is output from the microcomputer 21 to the drive circuit 22, and the drive circuit 22 energizes and de-energizes the fuel injection device 11 according to the rise timing and fall timing of the energization pulse.

Further, if the required injection amount Qr is equal to or greater than the threshold value Th1, the process proceeds to step S21. In step S21, it is determined that fuel injection in multi-stage energization mode will be performed this time.

In the following step S22, the number of stages of multi-stage energization is determined according to the required injection amount Qr. At this time, one or more threshold values larger than the threshold Th1 described above are determined, and the number of stages of multi-stage energization is determined according to the result of comparison between the required injection amount Qr and each threshold value. For example, in addition to the threshold value Th1, threshold values Th2 and Th3 are determined (Th1<Th2<Th3), and if the required injection amount Qr is within the range of Th1 to Th2, the 2-stage energization mode is set, and the required injection amount Qr is set to Th2. If the required injection amount Qr is within the range of ~Th3, the 3-stage energization mode is set, and if the required injection amount Qr is equal to or greater than Th3, the 4-stage energization mode is set. Note that the number of stages of multi-stage energization may be four or more.

Each of the threshold values Th1 to Th3 is the respective maximum injection amount when fuel injection is performed in the energization mode of each stage. That is, when the required injection amount Qr is equal to or greater than the threshold value Th1, it is assumed that the required injection amount Qr exceeds the maximum injection amount in the one-stage energization mode, and the two-stage or more stage energization mode is set. Further, when the required injection amount Qr is equal to or greater than the threshold value Th2, it is assumed that the required injection amount Qr exceeds the maximum injection amount in the two-stage energization mode, and the energization mode is set to three or more stages.

Each of the threshold values Th1 to Th3 may be configured to be variably set depending on the fuel pressure. For example, using the relationship shown in FIG. 8, the higher the fuel pressure, the larger the threshold values Th1 to Th3 are set.

Thereafter, in step S23, the energization time Tq and interval time TINT of each stage in multi-stage energization are set based on the energization time Tr calculated in step S12. In the two-stage energization mode, two energization times Tq1 and Tq2 and one interval time TINT are set. In the three-stage energization mode, three energization times Tq1, Tq2, and Tq3 and two interval times TINT1 and TINT2 are set. The same applies to energization modes of four or more stages.

The energization time Tq and interval time TINT of each stage may be set based on the fuel pressure. At this time, it is preferable that the energization time Tq of each stage is set based on the fuel pressure using the relationship shown in FIG. 4(a). Further, each interval time TINT may be set based on the fuel pressure using the relationship shown in FIG. 4(b).

Here, when multistage energization is performed, it is conceivable that the fuel pressure decreases during the subsequent stage energization due to the fuel injection caused by the first stage energization. The difference in fuel pressure affects the lift operation of the nozzle needle 32. Therefore, when energizing the latter stage, it is preferable to set the energization time Tq of each stage, taking into account that the fuel pressure is lower than when energizing the previous stage. That is, if the fuel pressure when the first stage is energized is PA, the fuel pressure when the second stage is energized is PA-ΔP1, and the fuel pressure when the third stage is energized is PA-(ΔP1+ΔP2). ΔP1 is the amount of fuel pressure reduction due to fuel injection due to first-stage energization, and ΔP2 is the amount of fuel pressure decrease due to fuel injection due to second-stage energization. Note that the fuel pressure PA is preferably the pressure detected by the pressure sensor 16 at the time of calculating the current required injection amount Qr.

Thereafter, in step S24, a correction value C is set corresponding to the response delay of needle lift-up that occurs at the start of energization in the second and subsequent stages, and the correction value C is used to adjust the energization time Tq and interval time TINT in the second and subsequent stages. Correct at least one of them. In this case, it is preferable to correct the energization time Tq of the final stage using the correction value C. In addition, a configuration may be adopted in which the energization time Tq of an intermediate stage other than the final stage is corrected by the correction value C, or the interval time TINT is corrected by the correction value C.

The correction value C may be set based on fuel pressure. At this time, it is preferable that the correction value C be set based on the fuel pressure using the relationship shown in FIG. However, the correction value C may be a predetermined fixed value. The correction value C may be a value determined for each fuel injection device 11, reflecting individual differences between the fuel injection devices 11 of each cylinder.

After that, in step S25, a plurality of energization pulses are generated depending on the energization mode each time. At this time, in the two-stage energization mode, two stages of energization pulses, front and rear, are generated based on the energization times Tq1 and Tq2 and the interval time TINT. In the three-stage energization mode, three stages of energization pulses are generated based on the energization times Tq1 to Tq3 and the interval times TINT1 and TINT2. The same applies to energization modes of four or more stages.

Thereafter, in step S26, the energization pulse is output. In this case, the microcomputer 21 outputs energization pulses for each stage to the drive circuit 22, and in the drive circuit 22, the fuel injection device 11 is energized and energized according to the rise timing and fall timing of the energization pulse to each stage. A cutoff is performed.

Further, in the present embodiment, when performing divided energization in multiple stages, the injection amount characteristics are adjusted in order to reduce the variation in the injection amount in each fuel injection having a different number of energization stages. In this case, the ECU 20 performs one-stage energization, which performs one-stage energization, and two-stage energization, which performs two-stage energization, in one injection opportunity, and obtains the actual injection amount in each of these energizations. Then, based on the actual injection amount in each energization, the adjustment amount of the injection characteristic data indicating the relationship between the energization time and the injection amount is calculated. In addition, in the fuel injection control, the energization time is determined based on the required injection amount each time using injection characteristic data.

Specifically, as shown in FIG. 9, in the injection characteristic data showing the relationship between energization time and injection amount, X1 is the energization time range in which one-stage energization can be performed, and X2 is the energization time range in which two-stage energization can be performed. Two adjustment points P1 and P2 are determined in the energization time range X1, and two adjustment points P3 and P4 are determined in the energization time range X2. Each of these adjustment points P1 to P4 is determined as a coordinate point consisting of a predetermined energization time and an injection amount on a basic characteristic line that is injection characteristic data. Adjustment points P1 and P2 correspond to "first adjustment points", and adjustment points P3 and P4 correspond to "second adjustment points".
- At adjustment point P1, the energization time is Tq11 and the injection amount is Q1.
- At adjustment point P2, the energization time is Tq12 and the injection amount is Q2.
- At adjustment point P3, the energization time is Tq13+Tq21 and the injection amount is Q3.
- At adjustment point P4, the energization time is Tq14+Tq22 and the injection amount is Q4.

Among the adjustment points P1 to P4, the fuel injection at adjustment points P2 and P3 is 1-stage energization and 2-stage energization, respectively, and the energization forms are different, but the total energization time and injection amount are the same. That is, "Tq12=Tq13+Tq21" and "Q2=Q3". In short, the fuel injection at the adjustment point P2 and the fuel injection at the adjustment point P3 are each performed with the same target injection amount.

In fuel injection at each of the adjustment points P1 to P4, deviations in the actual injection amount may occur at each of the adjustment points P1 to P4 due to individual differences in the fuel injection device 11, changes over time, and the like. Specifically, as shown in FIG. 10, it is conceivable that the actual injection amount deviates from the injection amount of the basic characteristic line including each adjustment point P1 to P4. In this case, injection amount deviations ΔQ1, ΔQ2, ΔQ3, and ΔQ4 occur at each adjustment point P1 to P4. In this embodiment, the adjustment amount of the injection characteristic data is calculated based on the injection amount deviations ΔQ1 to ΔQ4 at each adjustment point P1 to P4. Note that adjustment of the injection characteristic data is preferably performed for each fuel injection device 11 of each cylinder.

In FIG. 10, if there is a deviation in the actual injection amount that is excessive with respect to the injection amount on the basic characteristic line, the adjustment amount (adjustment time) by which the energization time Tq is shortened is used as the adjustment amount of the injection characteristic data. It would be good if it could be calculated. In addition, if there is a deviation where the actual injection amount is too small with respect to the injection amount on the basic characteristic line, the adjustment amount (adjustment time) by which the energization time Tq is extended is calculated as the adjustment amount of the injection characteristic data. It would be good if it were done. These adjustment amounts are preferably calculated as values according to the magnitude of the injection amount deviation.

FIG. 11 is a time chart for explaining fuel injection for characteristic adjustment at each adjustment point P1 to P4. In FIG. 11, (a) shows fuel injection at adjustment point P1, (b) shows fuel injection at adjustment point P2, (c) shows fuel injection at adjustment point P3, and (d) shows fuel injection at adjustment point P3. It shows the fuel injection at adjustment point P4, and shows the changes in the energization pulse, needle lift, and injection rate for each of these fuel injections. Note that the time integral value of the injection rate corresponds to the fuel injection amount, and in FIG. 11, the fuel injection amount for each adjustment is shown with hatching.

At the time of fuel injection at adjustment point P1, fuel injection is performed with one-stage energization in which the energization time is set to "Tq11". This fuel injection is a very small amount injection in which the needle lift does not reach the lift lower limit Lmin, and the injection amount is Q1.

At the time of fuel injection at adjustment point P2, fuel injection is performed with one-stage energization in which the energization time is set to "Tq12". This fuel injection is a fuel injection in which the needle lift is near the lift upper limit Lmax, and the injection amount is Q2. Note that the fuel injection at the adjustment point P2 is performed such that the needle lift falls within the range from the lower lift limit Lmin to the upper lift limit Lmax.

At the time of fuel injection at adjustment point P3, fuel injection is performed in two-stage energization with energization times set to "Tq13, Tq21". In this fuel injection, the injection amount is set to Q3, which is the same as the fuel injection amount at adjustment point P2, and the needle lift is set to the lower lift limit at the end of the first stage energization and at the start and end of the second stage energization. This is done so as to stay within the range from Lmin to the lift upper limit Lmax.

At the time of fuel injection at adjustment point P4, fuel injection is performed in two-stage energization with energization times set to "Tq14, Tq22". In this fuel injection, the injection amount is set to Q4 which is larger than the fuel injection at adjustment points P2 and P3, and the needle lift is set at the end of the first stage energization and at the start and end of the second stage energization. This is done so as to stay within the range from the lift lower limit Lmin to the lift upper limit Lmax.

When performing two-stage energization, a response delay of the nozzle needle 32 occurs when the nozzle needle 32 changes from lift-up to lift-down as the first-stage energization is stopped, and when the second-stage energization starts. When the nozzle needle 32 changes from lift-down to lift-up, a response delay of the nozzle needle 32 may occur. FIG. 12 is a time chart showing changes in the lift amount of the nozzle needle 32, in which a response delay time Td1 occurs when energization is stopped, and a response delay time Td2 occurs when energization is restarted.

In this case, if the interval time TINT in the second stage energization is made shorter than the response delay time Td1 when the first stage energization is stopped, there is a concern that the adjustment for the response delay will be insufficient. Furthermore, if the second-stage energization time Tq2 in the two-stage energization is made shorter than the response delay time Td2 at the time of restarting energization, there is a concern that the adjustment for the response delay may become insufficient. Therefore, when adjusting the injection characteristic data, the interval time TINT in the second stage energization is set to be longer than the response delay time Td1 when the first stage energization is stopped. Furthermore, the second-stage energization time Tq2 in the two-stage energization is set to be longer than the response delay time Td2 when energization is restarted. These response delay times Td1 and Td2 are preferably determined in advance as compatible values.

FIG. 13 is a flowchart showing the procedure of a characteristic adjustment process for adjusting injection characteristic data, and this process is repeatedly executed by the microcomputer 21 of the ECU 20 at a predetermined period.

In FIG. 13, in step S31, it is determined whether or not to perform fuel injection at adjustment point P1, in step S41, it is determined whether or not to perform fuel injection at adjustment point P2, and in step S51, It is determined whether or not to perform fuel injection at adjustment point P3, and in step S61, it is determined whether or not to perform fuel injection at adjustment point P4. Then, based on the determination results at each of these steps, fuel injection is performed at each adjustment point P1 to P4 as appropriate.

Here, the ECU 20 preferably performs each fuel injection (fuel injection at each adjustment point P1 to P4) for adjusting the injection characteristics in any of the following cases.
- When a characteristic adjustment command is input from an external device at a vehicle manufacturing factory or a vehicle repair shop, each fuel injection is performed to adjust the injection characteristics based on the characteristic adjustment command. In a configuration in which the adjustment results of the injection characteristics are stored in the backup RAM within the ECU 20, each fuel injection for adjusting the injection characteristics may be performed based on the characteristics adjustment command, for example, when replacing the battery.
・When the vehicle is coasting, each fuel injection is performed to adjust the injection characteristics. Specifically, when the vehicle is running, when the clutch of the power transmission system is disconnected when the accelerator is turned off and coasting is performed, that is, in a situation where the combustion of fuel in the engine 10 does not affect the running of the vehicle, the injection characteristics are Perform each fuel injection for adjustment. In this case, each fuel injection at one or more adjustment points may be performed during one coast run. Further, each fuel injection at each adjustment point P1 to P4 is preferably performed for each trip of the vehicle.

When performing fuel injection at the adjustment point P1, in step S32, conditions are set such that the energization time is Tq11 and the injection amount is Q1 as the injection conditions at the adjustment point P1, and fuel injection is performed under these conditions.

After that, in step S33, the actual injection amount when fuel injection is performed at the adjustment point P1 is acquired. The actual injection amount may be estimated, for example, based on a pressure change that occurs in the fuel supplied to the fuel injection device 11 due to fuel injection. Specifically, the ECU 20 calculates the amount of change in fuel pressure that occurs due to fuel injection by the fuel injection device 11 from the detected fuel pressure detected by the pressure sensor 16, and estimates the actual injection amount based on the amount of change in fuel pressure. In addition, the amount of change in rotational speed that occurs due to combustion of the injected fuel from the fuel injection device 11 (for example, the amount of change in instantaneous rotational speed for each predetermined crank angle) is calculated, and the actual injection amount is estimated based on the amount of change in rotational speed. It is also possible to do so.

Thereafter, in step S34, an adjustment amount of the injection characteristics is calculated at the adjustment point P1 based on the difference between the injection amount Q1, which is the target injection amount, and the actual injection amount obtained in step S33. At this time, if the injection amount is excessive with respect to the energization time at the adjustment point P1 as shown in FIG. 10, for example, an adjustment time for shortening the energization time is calculated as the adjustment amount.

In addition, when performing fuel injection at adjustment point P2, in step S42, conditions are set such that the energization time is Tq12 and the injection amount is Q2 as the injection conditions at adjustment point P2, and fuel injection is performed under these conditions. do. Thereafter, in step S43, the actual injection amount when fuel injection is performed at the adjustment point P2 is acquired.

Thereafter, in step S44, the adjustment amount of the injection characteristics is calculated at the adjustment point P2 based on the difference between the injection amount Q2, which is the target injection amount, and the actual injection amount obtained in step S43. At this time, if the injection amount is too small with respect to the energization time at the adjustment point P2 as shown in FIG. 10, for example, an adjustment time for lengthening the energization time is calculated as the adjustment amount.

In addition, when performing fuel injection at adjustment point P3, in step S52, as injection conditions at adjustment point P3, conditions are set such that the energization time is Tq13, Tq21 and the injection amount is Q3, and fuel injection is performed under these conditions. Implement. Thereafter, in step S53, the actual injection amount when fuel injection is performed at the adjustment point P3 is acquired.

Thereafter, in step S54, the adjustment amount of the injection characteristics is calculated at the adjustment point P3 based on the difference between the injection amount Q3, which is the target injection amount, and the actual injection amount obtained in step S53. At this time, if the injection amount is excessive with respect to the energization time at the adjustment point P3 as shown in FIG. 10, for example, an adjustment time for shortening the energization time is calculated as the adjustment amount.

In addition, when performing fuel injection at adjustment point P4, in step S62, as injection conditions at adjustment point P4, conditions are set such that the energization time is Tq14, Tq22 and the injection amount is Q4, and fuel injection is performed under these conditions. Implement. After that, in step S63, the actual injection amount when the fuel injection is performed at the adjustment point P4 is acquired.

Thereafter, in step S64, the adjustment amount of the injection characteristics is calculated at the adjustment point P4 based on the difference between the injection amount Q4, which is the target injection amount, and the actual injection amount obtained in step S63. At this time, if the injection amount is excessive with respect to the energization time at the adjustment point P4 as shown in FIG. 10, for example, an adjustment time for shortening the energization time is calculated as the adjustment amount.

In step S65, it is determined whether all adjustment amounts at each adjustment point P1 to P4 have been calculated. If step S65 is affirmed, the process proceeds to the subsequent step S66, and if negative, the process is temporarily ended.

In step S66, the injection characteristic data is adjusted using the adjustment amounts calculated for each of the adjustment points P1 to P4. Specifically, when the adjustment time is calculated as the adjustment amount at each adjustment point P1 to P4, each adjustment time at adjustment points P1 and P2 is linearly interpolated, and the interpolated data is used for adjustment with one-stage energization. Save as quantity. Further, each adjustment time at adjustment points P3 and P4 is linearly interpolated, and the interpolated data is stored as an adjustment amount in two-stage energization. At this time, the adjustment amounts are calculated so that the target injection amounts are the same at the adjustment points P2 and P3 where the injection amounts Q2 and Q3 are the same.

Note that the injection characteristic data may be adjusted for fuel injection in three-stage energization, in addition to fuel injection in first-stage energization and fuel injection in second-stage energization. In this case, the adjustment points at which the target injection amount is the same for fuel injection with 2-stage energization and fuel injection with 3-stage energization are determined as each adjustment point, and the actual injection amount matches at each adjustment point. It is preferable that the injection characteristic data be adjusted so as to.

In each fuel injection having a different number of energization stages (for example, one-stage energization and two-stage energization fuel injection), three or more adjustment points may be set. Further, a configuration may be adopted in which an adjustment injection amount for adjusting the injection amount is calculated as the adjustment amount of the injection characteristic data.

When the adjustment amount of the injection characteristic data is calculated, the energization time Tq is set using the adjustment amount. Specifically, in step S23 of the fuel injection control process of FIG. 7 described above, the energization time Tq of each stage is set using the adjustment amount of each stage. In step S12 of FIG. 7, the energization time Tr may be calculated using the adjustment amount in the first stage energization. Note that in the injection characteristic data adjustment process, the response delay of the nozzle needle 32 is corrected. Therefore, a configuration may be adopted in which the response delay correction in step S24 is omitted.

According to this embodiment described in detail above, the following excellent effects can be obtained.

When injecting fuel by the fuel injection device 11, the number of times of energization in one injection opportunity is determined, and during the injection period during which energization is performed, fuel injection at the maximum injection rate in an intermediate lift state is performed at each stage. The energization time Tq and the interval time TINT are set, and each stage is energized based on the energization time Tq and interval time TINT of each stage. In this case, by repeatedly increasing and decreasing the needle lift amount through multiple divided energizations for one fuel injection, the nozzle needle 32 can be brought into a desired intermediate lift state without expanding the intermediate lift region Rf of the fuel injection device 11. can be maintained. Further, during the energization period of each stage, injection can be continuously carried out at the maximum injection rate, linearity can be given to the fuel injection amount, and highly accurate fuel injection can be carried out.

Further, when fuel injection is performed by multiple stages of energization in one injection opportunity, it is desirable that the linearity of the fuel injection amount with respect to the energization time Tq be maintained regardless of the number of energization stages. In this regard, when at least one stage energization and two stage energization are performed in one injection opportunity, the adjustment amount of the injection characteristic data is calculated based on the actual injection amount in each energization. When the adjustment amount of the injection characteristic data is calculated, the energization time Tq is set using the adjustment amount. Thereby, even if the number of energization stages in one injection opportunity is changed, fuel injection can be appropriately performed at each of the energization stages. As a result, fuel injection control can be performed appropriately.

When adjusting the injection characteristics for the first-stage energization and the second-stage energization, the actual injection amount when fuel injection is performed at each adjustment point P2 and P3 with the injection amount set to the same target injection amount is obtained, and the adjustment point P2, The configuration is such that the adjustment amount for the first-stage energization and the adjustment amount for the second-stage energization are calculated based on the actual injection amount of P3. As a result, even if the number of energization stages is appropriately changed between one stage and two stages, the same and excellent linear characteristics can be maintained in both stages.

Multiple adjustment points are set for each fuel injection with a different number of energization stages (one-stage energization fuel injection, two-stage energization fuel injection), and injection characteristic data is generated based on the injection amount deviation at these multiple adjustment points. The configuration is such that the adjustment amount is calculated. In this case, the injection characteristic data can be appropriately adjusted by linear interpolation or the like for each fuel injection having a different number of energization stages.

When adjusting the injection characteristic data, the interval time TINT in the second stage energization is set to be longer than the response delay time when the first stage energization is stopped, and the second stage energization time Tq2 is set to the response delay time when the energization is resumed. Two-stage energization was performed for a time longer than the specified time. As a result, the injection characteristic data can be appropriately adjusted while taking into account that there is a delay in the response of the nozzle needle 32 when the first-stage energization is stopped and when the second-stage energization is started.

In the fuel injection device 11, the valve opening speed of the nozzle needle 32 upon the start of energization changes depending on the fuel pressure at each time. In this case, by setting the energization time Tq of each stage based on the fuel pressure, the nozzle needle 32 can be maintained in a desired intermediate lift state during the energization period of each stage while taking into account the opening speed of the nozzle needle 32. Can be done.

When multiple stages of energization are performed in one injection opportunity, fuel pressure decreases due to fuel injection when energizing the first stage and when energizing the second stage. In this case, multi-stage energization can be achieved by setting the energization time Tq of each stage in consideration of the fact that the fuel pressure (the pressure of the fuel injected by the fuel injection device 11) is lower when the later stage is energized than when the previous stage is energized. It is possible to further improve the accuracy in fuel injection control.

In the fuel injection device 11, the closing speed of the nozzle needle 32 upon termination of energization changes depending on the fuel pressure each time. In this case, by setting the interval time TINT based on the fuel pressure, the nozzle needle 32 can be maintained in a desired intermediate lift state during the energization period of each stage while taking into account the closing speed of the nozzle needle 32.

During actual operation of the fuel injection device 11, when the nozzle needle 32 changes from lift-down to lift-up at the start of energization in the second and subsequent stages, a response delay of the nozzle needle 32 occurs, which causes the injection amount to vary with respect to the energization time Tq. There is a concern that the linearity of the response will be impaired. In this regard, a correction value C corresponding to the response delay of needle lift-up that occurs at the start of energization in the second and subsequent stages is set, and by that correction value C, at least one of the energization time Tq and the interval time TINT of the second and subsequent stages is set. Since this is corrected, the linearity of the injection amount response to the energization time Tq can be maintained, and controllability can be improved.

In the fuel injection device 11, the degree of response delay (response delay time) of the nozzle needle 32 at the start of energization in the second and subsequent stages changes depending on the fuel pressure each time. In this case, by setting the correction value C based on the fuel pressure at each time, it is possible to ensure linearity of the injection amount response to the energization time Tq, regardless of the fuel pressure at each time.

The drive circuit 22 is configured to apply a high voltage and a low voltage, respectively, when energizing each stage. Thereby, it is possible to suppress the response delay of the nozzle needle 32 when the nozzle needle 32 changes from lift-down to lift-up at the start of energization in the second and subsequent stages. Therefore, a configuration suitable for improving the linearity of the injection amount response to the energization time can be realized.

(Other embodiments)
The above embodiment may be modified as follows, for example.

- In the above embodiment, both the energization time Tq and the interval time TINT of each stage are set variably based on the fuel pressure, but it is also possible to set only the energization time Tq variably based on the fuel pressure. good. That is, in the fuel injection device 11, when the valve is opened by energization, the high pressure fuel in the pressure control chamber 37 flows out to the low pressure chamber 64, so that the rate of fuel pressure drop in the pressure control chamber 37 is lower than the pressure on the high pressure side and the low pressure side. The lift operation of the nozzle needle 32 becomes dependent on the fuel pressure. In comparison, when the current supply is stopped, the lift operation of the nozzle needle 32 is less dependent on fuel pressure. Therefore, a configuration may be adopted in which only the energization time Tq is variably set based on the fuel pressure.

- In the above embodiment, the configuration is such that the energization pulse corresponding to the required injection amount Qr is divided into a plurality of parts as a configuration for performing multi-stage energization in one injection opportunity, but this may be changed. The energization pulse itself may be one pulse without being divided into a plurality of pulses, and a energization suspension period corresponding to the interval time TINT may be provided within the one pulse.

- In the above embodiment, when adjusting the injection characteristics for the first-stage energization and the second-stage energization, the target injection amounts Q2 and Q3 at the adjustment points P2 and P3 were set to be the same amount (Q2 = Q3), but this was changed. Good too. For example, target injection amounts Q2 and Q3 at adjustment points P2 and P3 are set to "Q2>Q3". In other words, the adjustment points for the first stage energization include the adjustment points where the injection amount is larger than the adjustment points for the second stage energization. In this case, the section where adjustments are made using adjustment points P1 and P2 in the first stage energization and the section where adjustments are made using adjustment points P3 and P4 during the second stage energization can be overlapped with each other, making it possible to further adjust the injection characteristics. It can be implemented appropriately. Note that it is also possible to set the target injection quantities Q2 and Q3 at the adjustment points P2 and P3 to be "Q2<Q3".

・Regarding the adjustment of the injection characteristic data, in the above configuration, two adjustment points P1 and P2 are set for the first stage energization, and two adjustment points P3 and P4 are set for the second stage energization, but this has been changed. Of these adjustment points P1 to P4, the injection characteristic data may be adjusted only at adjustment points P2 and P3 where the target injection amount is the same.

The control unit and the method described in the present disclosure are implemented by a dedicated computer provided by configuring a processor and memory programmed to perform one or more functions embodied by a computer program. may be done. Alternatively, the controller and techniques described in this disclosure may be implemented by a dedicated computer provided by a processor configured with one or more dedicated hardware logic circuits. Alternatively, the control unit and the method described in the present disclosure may be implemented using a combination of a processor and memory programmed to perform one or more functions and a processor configured by one or more hardware logic circuits. It may be implemented by one or more dedicated computers configured. The computer program may also be stored as instructions executed by a computer on a computer-readable non-transitory tangible storage medium.

DESCRIPTION OF SYMBOLS 10... Engine (internal combustion engine), 11... Fuel injection device, 32... Nozzle needle (valve body), 33... Nozzle hole, 60... Electric actuator (drive part), 20... ECU (fuel injection control device).

Claims (9)

It has a drive part (60) that is driven by energization, and a valve body (32) that opens the nozzle hole (33) according to the drive of the drive part, and controls the injection amount according to the energization time of the drive part. applied to a fuel injection system comprising a fuel injection device (11) that realizes a maximum injection rate by changing the valve body and achieving an intermediate lift state in which the lift amount of the valve body becomes a predetermined intermediate lift amount;
A fuel injection control device (20) that determines an energization time according to the injection amount using injection characteristic data indicating a relationship between the energization time and the injection amount, and energizes the drive unit according to the energization time,
The number of times the drive unit is energized in one injection opportunity is determined, and the energization time of each stage is determined so that fuel injection at the maximum injection rate in the intermediate lift state is performed during the injection period during which energization is performed. a time setting unit that sets an interval time between each of the energizations;
an energization control section that energizes the drive section based on the energization time of each stage and the interval time set by the time setting section;
When carrying out one-stage energization in which at least one stage of energization is performed and two-stage energization in which two stages of energization are performed in one injection opportunity, the actual injection amount that is the actual injection amount in each of these energizations is obtained. An injection amount acquisition unit;
a characteristic adjustment section that calculates an adjustment amount of the injection characteristic data based on the actual injection amount in each energization acquired by the injection amount acquisition section;
Equipped with
The injection amount acquisition unit performs the first-stage energization and the second-stage energization at adjustment points (P2, P3) where the injection amount is the same target injection amount, and calculates the actual injection amount at each adjustment point. Acquired,
The characteristic adjustment unit calculates the adjustment amount for the first-stage energization and the adjustment amount for the second-stage energization based on the actual injection amount at the adjustment point where the target injection amount becomes the same,
The time setting section is a fuel injection control device for an internal combustion engine that sets the energization time using the adjustment amount calculated by the characteristic adjustment section. It has a drive part (60) that is driven by energization, and a valve body (32) that opens the nozzle hole (33) according to the drive of the drive part, and controls the injection amount according to the energization time of the drive part. applied to a fuel injection system comprising a fuel injection device (11) that realizes a maximum injection rate by changing the valve body and achieving an intermediate lift state in which the lift amount of the valve body becomes a predetermined intermediate lift amount;
A fuel injection control device (20) that determines an energization time according to the injection amount using injection characteristic data indicating a relationship between the energization time and the injection amount, and energizes the drive unit according to the energization time,
The number of times the drive unit is energized in one injection opportunity is determined, and the energization time of each stage is determined so that fuel injection at the maximum injection rate in the intermediate lift state is performed during the injection period during which energization is performed. a time setting unit that sets an interval time between each of the energizations;
an energization control section that energizes the drive section based on the energization time of each stage and the interval time set by the time setting section;
When carrying out one-stage energization in which at least one stage of energization is performed and two-stage energization in which two stages of energization are performed in one injection opportunity, the actual injection amount that is the actual injection amount in each of these energizations is obtained. An injection amount acquisition unit;
a characteristic adjustment section that calculates an adjustment amount of the injection characteristic data based on the actual injection amount in each energization acquired by the injection amount acquisition section;
In the injection characteristic data, a plurality of first adjustment points (P1, P2) are set within a range where the first stage energization can be implemented, and a plurality of second adjustment points (P3) are set within a range where the second stage energization can be implemented. , P4);
Equipped with
The injection amount acquisition unit performs the first-stage energization and the second-stage energization at each of the plurality of first adjustment points and the plurality of second adjustment points, and acquires the actual injection amount at each of these energizations,
The characteristic adjustment unit calculates the adjustment amount at each energization based on the actual injection amount at the plurality of first adjustment points and the plurality of second adjustment points,
The time setting section is a fuel injection control device for an internal combustion engine that sets the energization time using the adjustment amount calculated by the characteristic adjustment section. It has a drive part (60) that is driven by energization, and a valve body (32) that opens the nozzle hole (33) according to the drive of the drive part, and controls the injection amount according to the energization time of the drive part. applied to a fuel injection system comprising a fuel injection device (11) that realizes a maximum injection rate by changing the valve body and achieving an intermediate lift state in which the lift amount of the valve body becomes a predetermined intermediate lift amount;
A fuel injection control device (20) that determines an energization time according to the injection amount using injection characteristic data indicating a relationship between the energization time and the injection amount, and energizes the drive unit according to the energization time,
The number of times the drive unit is energized in one injection opportunity is determined, and the energization time of each stage is determined so that fuel injection at the maximum injection rate in the intermediate lift state is performed during the injection period during which energization is performed. a time setting unit that sets an interval time between each of the energizations;
an energization control section that energizes the drive section based on the energization time of each stage and the interval time set by the time setting section;
When carrying out one-stage energization in which at least one stage of energization is performed and two-stage energization in which two stages of energization are performed in one injection opportunity, the actual injection amount that is the actual injection amount in each of these energizations is obtained. An injection amount acquisition unit;
a characteristic adjustment section that calculates an adjustment amount of the injection characteristic data based on the actual injection amount in each energization acquired by the injection amount acquisition section;
When performing multiple stages of energization in one injection opportunity, set a correction value corresponding to the response delay of valve body lift-up that occurs at the start of energization in the second and subsequent stages, and use that correction value to a correction unit that corrects at least one of the energization time and the interval time;
Equipped with
The time setting section is a fuel injection control device for an internal combustion engine that sets the energization time using the adjustment amount calculated by the characteristic adjustment section. The fuel injection control device for an internal combustion engine according to claim 3 , wherein the correction section sets the correction value based on the pressure of the fuel supplied to the fuel injection device. The injection amount acquisition unit is configured such that an interval time between first-stage energization and second-stage energization in the two-stage energization is longer than a response delay time when the valve body shifts to lift down due to energization stop. time, and the second-stage energization is performed such that the second-stage energization time is longer than a response delay time when the valve body shifts to lift-up upon resumption of energization. 5. The fuel injection control device for an internal combustion engine according to any one of 1 to 4 . The fuel injection control device for an internal combustion engine according to any one of claims 1 to 5 , wherein the time setting section sets the energization time of each stage based on the pressure of the fuel supplied to the fuel injection device. . 6. The time setting unit sets the energization time of each stage in consideration of the fact that the pressure of the fuel supplied to the fuel injection device is lower when the latter stage is energized than when the former stage is energized. A fuel injection control device for an internal combustion engine according to. The fuel injection control device for an internal combustion engine according to claim 1, wherein the time setting section sets the interval time based on the pressure of fuel supplied to the fuel injection device. The fuel injection device is provided with a drive circuit (22) that applies a high voltage at the beginning of energization and applies a low voltage subsequent to the application of the high voltage in response to an energization command to the fuel injection device,
9. The fuel injection control device for an internal combustion engine according to claim 1, wherein the drive circuit applies the high voltage and the low voltage, respectively, when each stage is energized.

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