JP6954043B2 - Fuel injection controller and processing system - Google Patents

Description

The present invention relates to a fuel injection control device and a processing system.

In a fuel injection system in which high-pressure fuel stored in a common rail as a pressure accumulator is injected from a fuel injection valve into a cylinder of an internal combustion engine, multi-stage injection includes pre-injection (for example, pre-injection) and subsequent in-stage injection (for example, main injection). When is carried out, the influence of the pressure pulsation generated by the pre-stage injection extends to the post-stage injection. Therefore, there is a concern that inconveniences such as fluctuations in the injection amount and injection timing of the subsequent injection may occur. In response to this inconvenience, it has been proposed to correct the injection amount and injection timing of the subsequent injection according to the interval time between injections.

Further, for example, in the technique described in Patent Document 1, when the subsequent injection is corrected according to the interval time between injections, the correction amount is adjusted in consideration of the fuel pressure in the common rail, the fuel temperature, and the high pressure passage length. I try to ask. As a result, highly accurate correction can be realized while considering the pressure pulsation of the high-pressure fuel generated by the pre-stage injection.

Japanese Unexamined Patent Publication No. 2003-314337

However, according to the findings of the inventors of the present application, it is considered that the influence of the pre-stage injection on the post-stage injection is other than the pressure pulsation caused by the pre-stage injection. This point will be described below.

The fuel injection valve is urged to the valve closing side by a nozzle needle that opens and closes the injection hole, a control chamber that is filled with high-pressure fuel and applies fuel pressure to the nozzle needle in the valve closing direction, and a urging means. It has a valve member that allows high-pressure fuel in the control chamber to flow out to the low-pressure chamber side by opening the valve, and a drive unit that moves the valve member to the valve opening position by energizing. Then, when the valve member moves to the valve opening position when the drive unit is energized, fuel injection is started, and when the valve member returns to the valve closing position when the energization is completed, fuel injection is terminated. In such a case, it is conceivable that the valve member bounces when the valve member returns to the closed position with the end of energization. Then, if the post-stage injection is started in a state where the valve member is bounced, there is a concern that the fuel injection amount may vary due to the influence. Further, it is considered that the bounce of the valve member varies from one fuel injection valve to another.

In recent years, shortening of the interval time in multi-stage injection has been studied, and it is considered that by performing so-called proximity injection in which the interval time is shortened, the fuel injection amount is likely to vary due to the bounce of the valve member.

With the existing technology including the technology described in Patent Document 1, it is difficult to suppress the variation in the fuel injection amount when the effect of the bounce of the valve member occurs, and it is considered that there is room for improvement in that respect. Be done.

The present invention has been made in view of the above problems, and a main object thereof is to provide a fuel injection control device and a processing system capable of appropriately performing fuel injection when performing multi-stage injection.

Hereinafter, means for solving the above problems and their actions and effects will be described.

The present invention
The accumulator container for storing high-pressure fuel and the fuel injection valve for injecting the high-pressure fuel supplied from the accumulator into the cylinder of the internal combustion engine are provided. A control chamber in which fuel is filled and fuel pressure is applied to the nozzle needle in the valve closing direction, and a valve closing side is urged by an urging portion, and high-pressure fuel in the control chamber is urged to the low-pressure chamber side by opening a valve. It is applied to a fuel injection system that has a valve member that flows out to the fuel and a drive unit that moves the valve member to the valve opening position by energization, and multiple fuel injections are performed in one combustion cycle of the internal combustion engine. It is a fuel injection control device that is implemented as injection.
A bounce characteristic value relating to the bounce behavior of the valve member after the end of energization of the drive unit is assigned to each fuel injection valve, and the bounce characteristic value is stored in the storage unit.
For each fuel injection valve, a characteristic acquisition unit that acquires the bounce characteristic value stored in the storage unit, and a characteristic acquisition unit.
At the time of performing the multi-stage injection, the interval time from the pre-stage injection of the multi-stage injection to the next post-stage injection or the injection amount of the post-stage injection is corrected based on the bounce characteristic value acquired by the characteristic acquisition unit. Correction part and
To be equipped.

In the fuel injection valve having the above configuration, when the valve member returns to the closed position with the end of energization, the valve member bounces, and there is a concern that the fuel injection amount may vary due to the bounce. In view of this point, the bounce characteristic value stored in the storage unit is acquired for each fuel injection valve, and at the time of performing the multi-stage injection, based on the acquired bounce characteristic value, the pre-stage injection of the multi-stage injection is followed by the next. The interval time until the latter stage injection or the injection amount of the latter stage injection is corrected. In this case, the bounce characteristic value indicates the bounce behavior of the valve member after the energization of the drive unit is completed, and the interval time or the injection amount of the subsequent injection is corrected by using the bounce characteristic value for each fuel injection valve. Thereby, for example, even if the bounce behavior of the valve member in the fuel injection valve differs from the reference characteristic, the variation in the fuel injection amount due to the difference can be suppressed. As a result, fuel injection can be properly performed when performing multi-stage injection.

The block diagram which shows the outline of the fuel injection system. Sectional drawing which shows the internal structure of a fuel injection valve. The figure for demonstrating the operation of a fuel injection valve. The figure for demonstrating the bounce of a control valve and the influence on the post-stage injection. A time chart showing the transition between the valve bounce of the control valve, the valve speed, the injection delay time, and the differential value thereof. The figure which shows the pattern of the bounce behavior of a control valve. The figure for demonstrating the effect of shortening the interval time in multi-stage injection. A flowchart showing a processing procedure for calculating an interval correction value. The figure for demonstrating the calculation of an interval correction value more concretely. The figure for demonstrating the calculation of an interval correction value more concretely. The flowchart which shows the processing procedure of fuel injection control. The figure which shows the effect about interval time correction.

Hereinafter, embodiments will be described with reference to the drawings. In the present embodiment, for example, in a common rail type fuel injection system (accumulation type fuel injection system) for controlling an in-vehicle diesel engine, a fuel injection control device for controlling fuel injection by a fuel injection valve and a fuel injection control device thereof are included. The processing system is to be embodied. In each of the following embodiments, parts that are the same or equal to each other are designated by the same reference numerals in the drawings, and the description thereof will be incorporated for the parts having the same reference numerals.

In FIG. 1, a fuel injection valve 11 is provided for each cylinder in a 4-cylinder diesel engine (hereinafter referred to as an engine 10) as an internal combustion engine, and these fuel injection valves 11 are provided on a common rail 12 (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, the fuel is increased in pressure as the high-pressure pump 13 is driven, 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 fuel is repeatedly sucked in and discharged 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 from the fuel tank 15 by the feed pump 14 passes through the suction metering valve 13a. 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 the fuel pressure (fuel pressure) in the common rail 12. The pressure sensor 16 may be provided at any position between the fuel outlet of the common rail 12 and the injection hole 33 (see FIG. 2) of the fuel injection valve 11 for each fuel injection valve 11. In this case, specifically, in each fuel injection valve 11, it is preferable that the pressure sensor 16 is provided in the high-pressure fuel passage through which the high-pressure fuel flows.

The ECU 20 is an electronic control unit equipped with a well-known microcomputer including a CPU and various memories (RAM, ROM, etc.), and performs various controls by a control program stored in the ROM. The ECU 20 includes, as a storage unit, a backup memory 21 made of a non-volatile memory such as EEPROM. In addition to the detection signal of the pressure sensor 16 described above, the ECU 20 has 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. Are input sequentially. Then, the ECU 20 determines the fuel injection amount and the injection timing as the fuel injection mode based on the engine operation information such as the engine rotation speed and the accelerator opening degree, and outputs an injection control signal corresponding to the fuel injection control signal to the fuel injection valve 11. By such fuel injection control, fuel injection from the fuel injection valve 11 to the combustion chamber is controlled in each cylinder. In the present embodiment, it is possible to carry out multi-stage injection in which fuel injection is performed a plurality of times in one combustion cycle, and as the multi-stage injection, for example, a main injection and a pre-injection performed prior to the main injection are carried out. For example, the pre-injection corresponds to the pre-stage injection, and the main injection corresponds to the post-stage injection.

Here, the structure of the fuel injection valve 11 will be described with reference to FIG. In FIG. 2, the vertical direction shows the axial direction of the fuel injection valve 11, and the lower side of the figure is the tip end side of the fuel injection valve 11.

In the fuel injection valve 11, a fixing plate 40 is integrally provided inside the body 31, and the nozzle needle 32 is housed on the tip side of the fixing plate 40 in a reciprocating state. A injection hole 33 is formed at the tip of the body 31, fuel injection is stopped when the injection hole 33 is closed by the nozzle needle 32, and fuel injection is performed by opening the injection hole 33 by the nozzle needle 32. Is done.

A high-pressure passage 34 is formed in the body 31 and the fixing plate 40 so as to penetrate the fixing 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 valve 11, that is, reaching the injection hole 33, and is supplied from the common rail 12 via the high-pressure passage 34. High-pressure fuel is guided to the injection hole 33.

A cylindrical cylinder 35 is attached to the tip end surface (lower end surface in the drawing) of the fixing plate 40, and the upper end portion of the nozzle needle 32 is slidably inserted into the cylinder 35. The nozzle needle 32 is urged in the valve closing direction by a spring 36 provided on the tip end side of the cylinder 35. A control chamber 37 is provided above the nozzle needle 32 in the cylinder 35. The control chamber 37 can be filled with high-pressure fuel, and when the control chamber 37 is filled with high-pressure fuel, the high-pressure fuel keeps the nozzle needle 32 closed. ..

The fixed plate 40 is formed with an inflow passage 41 for inflowing high-pressure fuel into the control chamber 37 and an outflow passage 42 for allowing fuel to flow out from the control chamber 37. The inflow passage 41 is provided as a branch from the high pressure passage 34, and an orifice that limits the fuel flow rate is formed in a downstream portion thereof (that is, a portion leading to the control chamber 37). Further, an orifice that limits the fuel flow rate is formed in the downstream portion of the outflow passage 42 (that is, the portion that leads to the low pressure chamber 64 described later).

A disk-shaped movable plate 50 is arranged in the control chamber 37. The movable plate 50 is arranged so as to face the lower end surface of the fixed plate 40, and can move in the control chamber 37 in the vertical direction shown in the drawing. The movable plate 50 is formed with a communication passage 51 that connects the outflow passage 42 and the control chamber 37. An orifice that limits the fuel flow rate is formed in the downstream portion of the communication passage 51. The movable plate 50 closes the outlet portion of the inflow passage 41 in a state of being in contact with the fixed plate 40, but maintains communication between the control chamber 37 and the outflow passage 42 via the orifice of the communication passage 51. There is. A spring 38 for pressing the movable plate 50 toward the fixed plate 40 is provided in the 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 peripheral surface of the movable plate 50 and the inner peripheral 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 control chamber 37 (specifically, the upper surface side of the nozzle needle 32) through the gap on the outer circumference of the movable plate 50. ..

Further, an electric actuator 60 is housed inside the body 31 on the side opposite to the tip of the fixed plate 40. The electric actuator 60 has a solenoid coil 61 as a drive unit, a control valve 62 as a valve member, and a spring 63 as an urging unit. The control valve 62 is movable in the vertical direction shown in the drawing in the low pressure chamber 64, and is held in a state of being pressed against the fixing plate 40 by the urging force of the spring 63 when the solenoid coil 61 is not energized, and the solenoid coil 62 is held. As the coil 61 is energized, it separates from the fixing plate 40 against the urging force of the spring 63.

In the electric actuator 60, it is also possible to use a drive unit having a piezo element. That is, it is also possible to use a piezo-driven fuel injection valve as the fuel injection valve 11.

Next, the operation of the fuel injection valve 11 will be described with reference to FIG. FIG. 3A shows a state before injection, FIG. 3B shows a state during injection, and FIG. 3C shows a state after injection ends. In FIG. 3, the portion of the fuel passage through which the fuel flows and where the high-pressure fuel is introduced is shaded.

In the state of FIG. 3A, the solenoid coil 61 is not energized and the control valve 62 is in the closed state. In this case, the outflow passage 42 of the fixing plate 40 is closed by the control valve 62, and the inside of the control chamber 37 is held in a high pressure state. Therefore, the fuel injection valve 11 is held in the closed state.

In the state of FIG. 3B, the control valve 62 moves to the valve opening position as the solenoid coil 61 is energized. As a result, the outflow passage 42 of the fixed plate 40 is opened, and the high-pressure fuel in the control chamber 37 flows out to the low-pressure chamber 64 side through the communication passage 51 of the movable plate 50. Then, as the pressure in the control chamber 37 drops, the nozzle needle 32 moves to the valve opening position, and fuel is injected from the injection hole 33.

In the state of FIG. 3C, the control valve 62 returns to the closed position due to the urging force of the spring 63 as the energization of the solenoid coil 61 is stopped. As a result, the fuel outflow from the outflow passage 42 is stopped. Further, the movable plate 50 is separated from the fixed plate 40 by increasing the pressure in the gap portion between the fixed plate 40 and the movable plate 50 as the fuel outflow is stopped. In this state, high-pressure fuel flows into the control chamber 37 from the inflow passage 41, and the nozzle needle 32 is returned to the valve closing position, so that fuel injection is stopped.

By the way, in the opening / closing operation of the fuel injection valve 11 as described above, when the control valve 62 closes due to the stoppage of energization of the solenoid coil 61, the control valve 62 bounces with respect to the fixed plate 40, which is caused by the bounce. Therefore, there is a concern that the fuel injection in the subsequent stage will be affected. The bounce of the control valve 62 and its influence on the post-stage injection will be described below. FIG. 4 illustrates injection pulses when performing pre-injection and main injection, and shows the lift of the control valve 62 as a valve lift.

In FIG. 4, before the timing t1, the control valve 62 is held in the valve closed position by the urging force of the spring 63, and when the injection pulse for pre-injection is started at the timing t1, the solenoid coil 61 The energization is started, and the lift of the control valve 62 is started. As a result, pre-injection is started at the fuel injection valve 11.

After that, when the injection pulse is defeated at the timing t2, the energization of the solenoid coil 61 is stopped, and the control valve 62 returns to the closed position by the urging force of the spring 63. After that, at the timing t3, the injection pulse for the main injection is started, the energization of the solenoid coil 61 is started again, and the lift of the control valve 62 is started. As a result, the main injection is started at the fuel injection valve 11.

After the pre-injection is stopped, the control valve 62 returns to the closed position once, but a bounce occurs when the lower end surface of the control valve 62 hits the upper surface of the fixed plate 40. Therefore, it is conceivable that energization of the main injection is started in a situation where the control valve 62 is bounced, and there is a concern that the fuel injection amount may vary due to the influence of the bounce in the main injection. That is, if energization of the main injection is started in a situation where the control valve 62 is bounced, the injection start timing after the start of energization varies. Therefore, there is a concern that the injection delay time TIS, which is the time required from the start of energization of the main injection to the actual start of injection, varies, and as a result, an error occurs in the fuel injection amount.

Immediately after the end of injection, one valve bounce cycle is, for example, about 50 μsec, and then the bounce cycle gradually shortens. It is considered that the above-mentioned valve bounce occurs in the period until a time of about 200 μsec elapses after the end of injection (after the end of energization).

FIG. 5 is a time chart showing the transition between the valve bounce of the control valve 62, the valve speed, the injection delay time TIS, and the differential value ΔTIS of the injection delay time TIS. In FIG. 5, regarding the injection delay time TIS, the case where energization is started at the timing of the valley of the valve bounce (valve lift amount = 0) is used as a reference value, and the magnitude relationship of the injection delay time TIS with respect to the reference value is shown. ..

In FIG. 5, the valve speed changes according to the occurrence of valve bounce, the valve speed changes at a positive speed when the valve rises when the control valve 62 moves to the valve opening side, and the control valve 62 moves to the valve closing side. When the moving valve descends, the valve speed changes at a negative speed. Then, the injection delay time TIS changes according to the bounce direction of the control valve 62 and the valve speed. At this time, if the valve speed is negative (during the valve is descending), the valve opening operation of the control valve 62 is hindered at the start of energization of the subsequent injection, so that the injection start is delayed and the injection delay time TIS is the reference value. Becomes larger than. If the valve speed is positive (while the valve is rising), the valve opening operation of the control valve 62 is assisted at the start of energization of the subsequent injection, so that the injection start is accelerated and the injection delay time TIS becomes the reference value. On the other hand, it becomes smaller.

Further, at the timing when the control valve 62 reaches the valve closing position (the position where the valve lift amount = 0), the valve speed changes from negative to positive at once, so that the injection delay time TIS is a value smaller to a larger value than the reference value. It has changed suddenly.

Here, if the energization of the subsequent injection is started at the timing of the valley of the valve bounce, the fuel injection is performed without being affected by the valve bounce (fluctuation of the injection delay time TIS), whereas the valve When the energization of the subsequent injection is started at a timing other than the bounce valley, the fuel injection is performed with the fluctuation of the injection delay time TIS due to the influence of the valve bounce. That is, if multi-stage injection is performed without considering the influence of valve bounce, it is conceivable that an excess or deficiency of the fuel injection amount unintentionally occurs.

It is considered that the bounce behavior of the control valve 62 as described above differs for each fuel injection valve 11. Therefore, even if the interval time between the first-stage injection and the second-stage injection is the same, it is considered that a difference in the injection delay time TIS due to the bounce behavior, that is, a variation in the fuel injection amount may occur. FIG. 6 shows three patterns (reference pattern, pattern A, and pattern B) of different bounce behaviors after the energization is cut off as the valve lift. In FIG. 6, the period of timing t11 to t12 is the energization period of the pre-injection, and the period after the timing t13 is the energization period of the main injection. In the reference pattern, the timing of the valley of the valve bounce and the timing of starting energization of the main injection coincide with each other.

In the pattern A shown in FIG. 6, the bounce cycle is larger than that of the reference pattern, and in the pattern B, the bounce cycle is smaller than that of the reference pattern. Therefore, at the start of energization of the main injection, the position of the control valve 62 and the direction of the bounce are different in each pattern. That is, at the start of energization of the main injection, energization is started at the timing of the bounce valley in the reference pattern, whereas energization is started at the timing other than the bounce valley in the patterns A and B. In this case, in particular, in pattern A, energization is started in the down section where the control valve 62 is about to return to the closed position, and in pattern B, energization is started in the up section where the control valve 62 is about to leave the closed position. NS.

In the case of pattern A, at the timing t13, which is the energization start timing of the main injection, the control valve 62 is not in the valve closing position, and the control valve 62 is in the process of moving toward the valve closing position (while the valve is descending). ing. Therefore, it is conceivable that the injection delay time TIS becomes larger than the reference value of the reference pattern after the start of energization of the main injection at the timing t13, and the actual fuel injection amount unintentionally decreases due to this.

Further, in the case of the pattern B, the control valve 62 is not in the valve closing position at the timing t13, which is the energization start timing of the main injection, and the control valve 62 is in the process of moving away from the valve closing position (while the valve is rising). It has become. Therefore, it is conceivable that the injection delay time TIS becomes smaller than the reference value of the reference pattern after the start of energization of the main injection at the timing t13, and the actual fuel injection amount increases unintentionally due to this.

In the present embodiment, the bounce characteristic of the control valve 62 after the end of energization is grasped for each fuel injection valve 11, and the fuel injection amount control in multi-stage injection is performed in consideration of the bounce characteristic. In this case, in the memory 21 in the ECU 20, for each fuel injection valve 11, as a bounce characteristic value regarding the bounce behavior of the control valve 62 after the end of energization, the interval time Tint from the pre-injection of the multi-stage injection to the next post-injection is performed. The interval correction value ΔTc for correcting the above is stored. Then, the ECU 20 acquires the interval correction value ΔTc stored in the memory 21 for each fuel injection valve 11, and corrects the interval time Tint based on the interval correction value ΔTc. The interval correction value ΔTc indicates whether the bounce cycle of the control valve 62 after the end of energization of the pre-stage injection is larger or smaller than the reference cycle, and is a positive correction value or a negative depending on the bounce cycle. It is defined as a correction value. At this time, the ECU 20 corrects the interval time Tint so that the timing of the bounce valley of the control valve 62 after the end of energization of the pre-stage injection coincides with the energization start timing of the post-stage injection. That is, by this correction, the injection pulse is started at the timing when the bounce valley of the control valve 62 is reached. The interval time Tint is a time interval from the energization end timing of the pre-stage injection to the energization start timing of the subsequent post-stage injection. In this embodiment, the ECU 20 corresponds to the characteristic acquisition unit and the correction unit.

As a configuration for grasping the bounce characteristic, in the embodiment, the bounce characteristic value regarding the bounce behavior of the control valve 62 at each fuel injection valve 11 is calculated before the product is shipped from the factory, and the calculation result is calculated by the fuel injection valve 11. It is supposed to be stored in the storage unit for each storage. Specifically, as shown in FIG. 1, a characteristic calculation device for the ECU 20 in a shipping inspection (EOL: End Of Line) at any manufacturing plant such as a fuel injection valve 11, a fuel injection system, or a vehicle. 70s are connected so that they can communicate with each other. The characteristic calculation device 70 has a microcomputer composed of a CPU and various memories, and calculates a bounce characteristic value for each fuel injection valve 11 in a state where multi-stage injection is performed in the fuel injection system. There is.

More specifically, the characteristic calculation device 70 determines whether the energization start timing of the rear stage injection is in the down section or the up section of the bounce of the control valve 62 after the end of energization of the front stage injection when the multi-stage injection is performed. judge. Then, when it is determined that the energization start timing of the latter stage injection is in the down section, the interval correction value ΔTc for increasing the interval time Tint is set as the bounce characteristic value, and the energization start timing of the second stage injection is in the up section. When it is determined, the interval correction value ΔTc that reduces the interval time Tint is set as the bounce characteristic value.

Further, in particular, the characteristic calculation device 70 sets the interval time Tint differently for each predetermined width, and causes the multi-stage injection to be performed at the interval time Tint. At that time, the injection delay time TIS was calculated from the injection start timing of the fuel injection valve 11 after the start of energization of the subsequent injection, and the injection delay time TIS (injection start timing) suddenly changed as the interval time Tint increased or decreased. In this case, the interval correction value ΔTc is set based on the interval time Tint at that time. In the present embodiment, the characteristic calculation device 70 corresponds to the section determination unit, the correction value setting unit, the interval time setting unit, and the calculation unit.

The injection delay time TIS may be calculated from the point of decrease in fuel pressure after the start of energization of the fuel injection valve 11. In this case, the characteristic calculation device 70 inputs the detection value (actual pressure) of the pressure sensor 16 from the ECU 20 and calculates the injection delay time TIS based on the injection start timing obtained by the change in the actual pressure.

In multi-stage injection, it is generally assumed that the interval time Tint is set to 200 μsec or more, but by shortening the interval time Tint to 200 μsec or more and performing so-called proximity injection, the effect of improving fuel efficiency and It is considered that the effect of reducing exhaust emissions and the effect of suppressing noise can be expected. The effect is shown in FIG. FIG. 7A shows the effect of improving fuel efficiency (BSFC) and the effect of suppressing noise due to the shortening of the interval time Tint, and FIG. 7B shows the effect of suppressing noise due to the shortening of the interval time Tint, and FIG. 7B shows carbon monoxide (CO) due to the shortening of the interval time Tint. (C) shows the effect of reducing hydrocarbons (HC) and the effect of suppressing noise due to the shortening of the interval time Tint, and (d) shows the effect of suppressing noise. The effect of reducing soot (Soot) and the effect of suppressing noise due to the shortening of Tint are shown.

If the interval time Tint is shortened as described above, various effects can be obtained, but there is a concern that the fuel injection amount of the fuel injection valve 11 varies due to the bounce of the control valve 62. In this embodiment, the interval time Tint is shortened without any inconvenience, and the fuel injection control is optimized.

FIG. 8 is a flowchart showing a processing procedure for calculating the interval correction value ΔTc according to the bounce characteristic of the fuel injection valve 11, and this processing is performed for each engine 10 by the characteristic calculation device 70 in the factory shipment inspection at the manufacturing factory. In other words, it is carried out for each fuel injection system.

In FIG. 8, in step S11, the injection conditions by the fuel injection valve 11 are set. At this time, assuming that the characteristic calculation device 70 executes the pre-injection and the main injection as multi-stage injection, for example, the injection amount of the pre-injection, the injection amount of the main injection, the reference interval time Tint0, and the fuel pressure are set. Set. The reference interval time Tint0 is a reference value of the interval time Tint between the pre-injection and the main injection, and is, for example, 100 μsec. In the present embodiment, the interval correction value ΔTc at each fuel injection valve 11 is sequentially calculated after keeping the injection conditions constant. The reference interval time Tint0 is set as the time from the end of energization of the pre-injection to the timing of the bounce valley of the control valve 62 in the standard fuel injection valve (master injector).

In step S12, the fuel injection valve 11 for calculating the interval correction value ΔTc as the bounce characteristic value is determined. At this time, for example, in the case of a fuel injection system of a 4-cylinder engine, the fuel injection valves 11 are designated one by one in order from the fuel injection valve 11 of the first cylinder as the fuel injection valve 11 to be calculated. In step S13, the number of updates n of the interval time Tint is set to 0.

After that, in step S14, the fuel injection system performs multi-stage injection at the reference interval time Tint0, and calculates the injection delay time TIS (0) when the multi-stage injection is performed. The characteristic calculation device 70 detects the injection start timing of the fuel injection valve 11 based on the change in the actual fuel pressure (change on the decreasing side) acquired from the ECU 20, and also delays the injection due to the time required from the start of energization to the start of injection. Calculate the time TIS.

After that, in step S15, when the multi-stage injection is performed at the reference interval time Tint0, it is determined whether the energization start timing of the main injection is in the down section or the up section of the valve bounce. Specifically, it is determined whether or not the injection delay time TIS (0) is larger than the reference value. At this time, if the injection delay time TIS (0)> the reference value, it is determined that the bounce down section is reached, and the process proceeds to step S16. If the injection delay time TIS (0)> the reference value is not satisfied, the bounce up section is determined. It is determined that the above is true, and the process proceeds to step S21.

In the case of the bounce descent section, in step S16, the update count n is incremented by 1. In the following step S17, a new interval time Tinten is set by adding the time of “n × ΔT” to the reference interval time Tint0. That is, it is updated to the side where the interval time Tint is increased. In step S18, the multi-stage injection is performed at the update number n at the interval time Tinnt, and the injection delay time TIS (n) when the multi-stage injection is performed is calculated.

After that, in step S19, it is determined whether or not the injection delay time TIS suddenly changes as the interval time Tint increases (that is, whether or not the injection start timing of the subsequent injection suddenly changes). For example, whether or not the injection delay time TIS suddenly changed depending on the injection delay time TIS (n) calculated in the current multi-stage injection and the injection delay time TIS (n-1) calculated in the previous multi-stage injection. Is determined. At this time, when the injection delay time TIS (n-1) is larger than the reference value and the injection delay time TIS (n) is smaller than the reference value, it is determined that the injection delay time TIS has changed suddenly. If the injection delay time TIS has not changed suddenly, step S19 is denied and the process returns to step S16. In this case, the processes of steps S16 to S19 are performed again.

The time difference ΔTISn is calculated by subtracting the injection delay time TIS (n-1) calculated in the previous multi-stage injection from the injection delay time TIS (n) calculated in this multi-stage injection (ΔTISn =). Whether or not there is a sudden change in the injection delay time TIS may be determined based on whether TIS (n) -TIS (n-1)) and the time difference ΔTISn are negative values.

If the injection delay time TIS changes suddenly, step S19 is affirmed and the process proceeds to step S20. In step S20, “n × ΔT” is calculated as the interval correction value ΔTc with respect to the reference interval time Tint0.

Further, in the case of the bounce ascending section, in step S21, the update count n is incremented by 1. In the following step S22, a new interval time Tinten is set by subtracting the time of "n × ΔT" from the reference interval time Tint0. That is, it is updated to the side where the interval time Tint is reduced. In step S23, the multi-stage injection is performed at the update number n at the interval time Tinnt, and the injection delay time TIS (n) when the multi-stage injection is performed is calculated.

After that, in step S24, it is determined whether or not the injection delay time TIS suddenly changes as the interval time Tint decreases (that is, whether or not the injection start timing of the subsequent injection suddenly changes). For example, whether or not the injection delay time TIS suddenly changed depending on the injection delay time TIS (n) calculated in the current multi-stage injection and the injection delay time TIS (n-1) calculated in the previous multi-stage injection. Is determined. At this time, when the injection delay time TIS (n-1) is smaller than the reference value and the injection delay time TIS (n) is larger than the reference value, it is determined that the injection delay time TIS has changed suddenly. If the injection delay time TIS has not changed suddenly, step S24 is denied and the process returns to step S21. In this case, the processes of steps S21 to S24 are performed again.

The time difference ΔTISn is calculated by subtracting the injection delay time TIS (n-1) calculated in the previous multi-stage injection from the injection delay time TIS (n) calculated in this multi-stage injection (ΔTISn =). Whether or not there is a sudden change in the injection delay time TIS may be determined based on whether TIS (n) -TIS (n-1)) and the time difference ΔTISn are positive values.

If the injection delay time TIS changes suddenly, step S24 is affirmed and the process proceeds to step S25. In step S25, “−n × ΔT” is calculated as the interval correction value ΔTc with respect to the reference interval time Tint0.

When the calculation of the interval correction value ΔTc in step S20 or step S25 is completed, the process proceeds to step S26. In step S26, it is determined whether or not the calculation of the interval correction value ΔTc is completed for all the fuel injection valves 11 in the present injection system, that is, the fuel injection valves 11 for the number of engine cylinders. Then, if the calculation of the interval correction value ΔTc for any of the fuel injection valves 11 is not completed, the process returns to step S12. Returning to step S12, the interval correction value ΔTc is calculated for the next fuel injection valve 11.

If the calculation of the interval correction value ΔTc for all the fuel injection valves 11 is completed, the process proceeds to step S27, and the interval correction value ΔTc of each fuel injection valve 11 is stored in the memory 21. At this time, the characteristic calculation device 70 transmits the information of the interval correction value ΔTc to the ECU 20, and stores the interval correction value ΔTc in the memory 21 in the ECU 20.

In addition to the above, as a method for storing the interval correction value ΔTc, a method of encoding the interval correction value ΔTc and printing it as readable information may be used. Specifically, the interval correction value ΔTc may be coded by a QR code (registered trademark), and a sheet or plate on which the QR code is printed may be attached to the outer surface of the fuel injection valve 11. In this case, the correction value information read by the code reading device may be transmitted to the ECU 20.

The interval correction value ΔTc in each fuel injection valve 11 may be calculated for each of a plurality of injection conditions. For example, the fuel pressure is determined in a plurality of stages, and the interval correction value ΔTc of each fuel injection valve 11 is calculated for each fuel pressure. Further, a plurality of reference interval times Tint0 are set, and the interval correction value ΔTc of each fuel injection valve 11 is calculated for each reference interval time Tint0.

Here, the calculation of the interval correction value ΔTc will be described more specifically with reference to FIGS. 9 and 10. Note that FIG. 9 shows a state in which the energization start timing of the subsequent stage injection is set in the downward section of the valve bounce when the subsequent stage injection is performed at the reference interval time Tint0 (corresponding to pattern A in FIG. 6). Further, FIG. 10 shows a state in which the energization start timing of the subsequent stage injection is set in the upstream section of the valve bounce when the subsequent stage injection is performed at the reference interval time Tint0 (corresponding to pattern B in FIG. 6).

In FIG. 9, the injection delay time TIS (0) calculated at the time of multi-stage injection at the reference interval time Tint0 determines that the energization start timing is in the downward section of the valve bounce, and then the multi-stage at the interval times Tint1 and Tint2. The injection delay times TIS (1) and TIS (2) are calculated at the time of injection. Then, the injection delay time is calculated as "ΔTc = 2 × ΔT2" due to a sudden change between TIS (1) and TIS (2).

Further, in FIG. 10, it is determined by the injection delay time TIS (0) calculated at the time of multi-stage injection at the reference interval time Tin0 that the energization start timing is in the upstream section of the valve bounce, and then at the interval times Tint1 and Tint2. The injection delay times TIS (1) and TIS (2) are calculated at the time of multi-stage injection. Then, the injection delay time is calculated as "ΔTc = -2 × ΔT2" due to a sudden change between TIS (1) and TIS (2).

In FIGS. 9 and 10, in each fuel injection valve 11, the difference in bounce behavior from the standard fuel injection valve 11 (master injector) is stored in the memory 21 as an interval correction value ΔTc.

FIG. 11 is a flowchart showing a processing procedure of fuel injection control, and this processing is performed by the ECU 20 at a predetermined cycle while the IG switch of the vehicle is turned on.

In FIG. 11, in step S31, it is determined whether or not the current fuel injection is multi-stage injection, and in the following step S32, in the second and subsequent stages of multi-stage injection, the interval time Tint with the previous stage injection is TH for a predetermined time. It is determined whether or not an item having a value of less than (for example, 200 μsec) is included. That is, it is determined whether or not it is necessary to consider the bounce behavior of the control valve 62 in the fuel injection this time. Here, if Tin <TH, the process proceeds to step S33 assuming that the bounce behavior of the control valve 62 is taken into consideration, and if Tin ≧ TH, the process proceeds to step S35 as it is without considering the bounce behavior of the control valve 62.

In step S33, the interval correction value ΔTc is read from the memory 21 for the fuel injection valve 11 of the combustion cylinder this time, and in the following step S34, the interval time Tint between the pre-injection and the main injection is used by using the interval correction value ΔTc. (Corrected Tint = Tint + ΔTc). At this time, if the fuel injection valve 11 corresponds to the pattern A in FIG. 6, the interval time Tint is corrected to the increasing side, and if the fuel injection valve 11 corresponds to the pattern B in FIG. 6, the interval time Tint decreases. It is corrected to the side. In step S34, assuming that the interval time Tint is set at the reference interval time Tint0, it is preferable that the correction is performed so that the interval time Tint is corrected. However, even when the interval time Tint is set other than the reference interval time Tint0, it is preferable that the correction by the interval correction value ΔTc is performed.

After that, in step S35, the injection conditions for the current fuel injection are set. At this time, if the single-shot injection is performed, the injection amount and the injection timing of the single-shot injection are set. Further, in the case of performing multi-stage injection, when the interval time Tint is corrected as described above, the injection conditions of each stage are set using the corrected interval time Tint, and the interval time Tint is corrected. If not (when step S32 is NO), the injection conditions of each stage are set by using the uncorrected interval time Tint (reference interval time Tint0).

FIG. 12 is a diagram showing the effect of the interval time correction of the present embodiment, in which the horizontal axis represents the interval time Tint (indicated value) and the vertical axis represents the fuel injection amount. (A) shows the relationship between the interval time Tint and the fuel injection amount when the correction is not performed, and (b) shows the relationship between the interval time Tint and the fuel injection amount when the correction is performed. There is. The solid line indicates the standard fuel injection valve (master injector), and the broken line indicates the fuel injection valve 11 to be corrected.

In FIG. 12A, due to the variation in the bounce behavior of the fuel injection valve 11, the fuel injection amount differs between the master injector and the fuel injection valve 11 to be corrected even if the interval time Tint is the same. ing. On the other hand, in FIG. 12B, the difference in fuel injection amount between the master injector and the fuel injection valve 11 to be corrected is reduced by correcting the interval time Tint.

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

In the fuel injection valve 11 having the above configuration, when the control valve 62 returns to the closed position with the end of energization, the control valve 62 bounces, and there is a concern that the fuel injection amount may vary due to the bounce. Will be done. In view of this point, the interval correction value ΔTc (bounce characteristic value) stored in the memory 21 is acquired for each fuel injection valve 11, and the interval time Tint is set based on the interval correction value ΔTc at the time of performing multi-stage injection. I tried to correct it. In this case, even if the bounce behavior of the control valve 62 in each fuel injection valve 11 differs from the reference characteristic, the variation in the fuel injection amount due to the difference can be suppressed. As a result, fuel injection can be properly performed when performing multi-stage injection.

If the bounce cycle of the control valve 62 after the completion of energization of the first stage injection is larger than the reference cycle, the injection amount of the second stage injection is smaller than the required injection amount (pattern A in FIG. 6), and the bounce cycle of the control valve 62 becomes smaller. If it is smaller than the reference period, the injection amount of the subsequent injection will be larger than the required injection amount (Pattern B in FIG. 6). In consideration of this point, the interval time Tint is increased or decreased according to whether the bounce period of the control valve 62 is larger or smaller than the reference period. In this case, proper fuel injection control can be performed for each fuel injection valve 11 while grasping the variation in the bounce cycle of the control valve 62 after the end of energization.

When the interval time Tint of multi-stage injection is shortened to, for example, 200 μsec, so-called proximity injection can be expected to have an effect of improving fuel efficiency, an effect of reducing exhaust emissions, and an effect of suppressing noise. However, on the other hand, there is a concern that the fuel injection amount may vary due to valve bounce. In view of this point, the interval time Tint is corrected based on the interval correction value ΔTc on condition that the interval time Tint is smaller than the predetermined time. Therefore, the effect of reducing the variation in the fuel injection amount while obtaining the above effect is obtained. Can be obtained.

The interval time Tint is corrected by matching the timing of the bounce valley of the control valve 62 after the end of energization of the pre-stage injection with the energization start timing of the post-stage injection. As a result, even if the bounce behavior of the control valve 62 after the end of energization of the pre-stage injection is different for each fuel injection valve 11, the start of energization of the fuel injection valve 11 can be matched with the bounce behavior.

When it is determined that the energization start timing of the latter stage injection is in the down section, the interval correction value ΔTc is set so as to increase the interval time Tint, and it is determined that the energization start timing of the second stage injection is in the up section. In addition, the interval correction value ΔTc is set so as to reduce the interval time Tint. As a result, the interval time Tint can be appropriately controlled with reference to the timing of the bounce valley of the control valve 62.

Multi-stage injection is performed at the interval time Tint set for each predetermined width, and the injection start timing of the fuel injection valve 11 after the start of energization of the subsequent stage injection is calculated, and injection is performed as the interval time Tint increases or decreases. When the start timing suddenly changes, the interval correction value ΔTc is set based on the interval time Tint at that time. In this case, if the interval time Tint is gradually increased or decreased, the interval correction value ΔTc is appropriately adjusted by utilizing the fact that the injection start timing suddenly changes when the energization start timing crosses the bounce valley of the control valve 62. Can be asked for.

In the shipping inspection at the product factory, the characteristic calculation device 70 connected to the ECU 20 calculates the interval correction value ΔTc as the bounce characteristic value and stores it in the memory 21. As a result, proper fuel injection control by the ECU 20 can be realized immediately after the vehicle is shipped from the factory.

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

-In the above embodiment, the reference interval time Tint0 is set as the time until the valve bounce valley occurs after the end of pre-injection energization in the standard fuel injection valve (master injector), but even if this is changed. Often, the reference interval time Tint0 may be set as the time until a timing other than the timing at which the valve bounce valley occurs. In any case, by considering the bounce behavior of the control valve 62 in each fuel injection valve 11, it is possible to suppress the variation in the injection amount of the subsequent injection in each fuel injection valve 11.

-In the above embodiment, the characteristic calculation device 70 calculates the bounce characteristic value related to the bounce behavior of the fuel injection valve 11 before the product is shipped from the factory. However, this is changed and the in-vehicle ECU 20 uses the fuel. The bounce characteristic value regarding the bounce behavior of the injection valve 11 may be calculated. In this case, the ECU 20 may perform the calculation process of the interval correction value ΔTc shown in FIG. Specifically, after the IG switch of the vehicle is turned on, a calculation period (calculation condition) for calculating the interval correction value ΔTc is set in advance, and in the calculation period, the injection delay is set while the interval time Tint is variably set. The interval correction value ΔTc may be calculated based on the change in time TIS. For example, under the condition that the engine operating state is constant, the interval correction value ΔTc may be calculated while setting the interval time Tin variably.

-In the above embodiment, the interval time Tint is corrected based on the interval correction value ΔTc as the bounce characteristic value at the time of performing the multi-stage injection, but this is changed and the post-stage injection is performed based on the interval correction value ΔTc. It may be configured to correct the injection amount of. In this case, if the interval correction value ΔTc indicates that the bounce period of the control valve 62 is larger than the reference period (Pattern A in FIG. 6), a correction for increasing the injection amount of the subsequent injection is performed. .. If the interval correction value ΔTc indicates that the bounce period of the control valve 62 is smaller than the reference period, a correction is performed to reduce the injection amount of the subsequent injection.

-The configuration is such that the interval correction value ΔTc, which is the difference value from the reference interval time Tint0, is calculated as the bounce characteristic value, but this may be changed, and the information regarding the bounce cycle of the control valve 62 is used as the bounce characteristic value. It may be a configuration to be calculated. For example, as the bounce characteristic value, a characteristic value corresponding to the difference between the bounce period of the control valve 62 and the reference period is calculated, and the characteristic value is stored in the memory 21. In this case, when the multi-stage injection is performed, if the bounce cycle of the control valve 62 is larger than the reference cycle, the ECU 20 makes a correction to increase the interval time Tint, and the bounce cycle of the control valve 62 is larger than the reference cycle. If it is small, a correction is performed to reduce the interval time Tint.

-If the fuel temperature is different, the flow rate flowing through the fuel passage in the fuel injection valve 11 (particularly the flow rate passing through the orifice) changes. In consideration of this point, the interval time Tint may be corrected. For example, at low temperatures, it is assumed that the bounce of the control valve 62 becomes smaller (the bounce cycle becomes smaller) due to the decrease in the orifice flow rate. Therefore, in consideration of this point, the interval correction value ΔTc is calculated or the interval is calculated. It is advisable to correct the time tint.

-In the above embodiment, the present invention has been applied to a fuel injection system of a diesel engine, but the present invention is not limited to this, and the present invention can also be applied to a fuel injection system of a direct injection gasoline engine. In this case, in the fuel injection system in which the high-pressure fuel accumulated and held in the delivery pipe as the accumulator container is injected by the fuel injection valve, the fuel injection at the time of performing the multi-stage injection can be appropriately performed.

10 ... Engine (internal combustion engine), 11 ... Fuel injection valve, 12 ... Common rail (accumulation container), 20 ... ECU (fuel injection control device), 32 ... Nozzle needle, 33 ... Injection hole, 37 ... Control room, 61 ... Solenoid Coil (drive unit), 62 ... control valve (valve member), 63 ... spring (urging unit), 64 ... low pressure chamber.

Claims (8)

The accumulator container (12) for storing high-pressure fuel and the fuel injection valve (11) for injecting the high-pressure fuel supplied from the accumulator container into the cylinder of the internal combustion engine (10) are provided. Closed by a nozzle needle (32) that opens and closes (33), a control chamber (37) that is filled with the high-pressure fuel and applies fuel pressure to the nozzle needle in the valve closing direction, and an urging portion (63). A valve member (62) that is urged to the valve side and causes the high-pressure fuel in the control chamber to flow out to the low-pressure chamber (64) side by opening the valve, and a drive unit (61) that moves the valve member to the valve opening position by energizing. A fuel injection control device (20), which is applied to a fuel injection system having () and performs a plurality of fuel injections as multi-stage injections in one combustion cycle of the internal combustion engine.
A bounce characteristic value relating to the bounce behavior of the valve member after the end of energization of the drive unit is assigned to each fuel injection valve, and the bounce characteristic value is stored in the storage unit (21).
For each fuel injection valve, a characteristic acquisition unit that acquires the bounce characteristic value stored in the storage unit, and a characteristic acquisition unit.
At the time of performing the multi-stage injection, the interval time from the pre-stage injection of the multi-stage injection to the next post-stage injection or the injection amount of the post-stage injection is corrected based on the bounce characteristic value acquired by the characteristic acquisition unit. Correction part and
A fuel injection control device comprising. The bounce characteristic value indicates whether the bounce cycle of the valve member after the end of energization of the pre-stage injection is larger or smaller than the reference cycle for each fuel injection valve.
The correction unit
When it is shown that the bounce cycle of the valve member is larger than the reference cycle, a correction is made to increase the interval time or increase the injection amount of the subsequent injection.
The fuel injection control according to claim 1, wherein when it is shown that the bounce cycle of the valve member is smaller than the reference cycle, a correction is made to reduce the interval time or the injection amount of the subsequent injection. Device. An interval time determination unit for determining that the interval time is smaller than a predetermined time when performing the multi-stage injection is provided.
The fuel injection control device according to claim 1 or 2, wherein the correction unit performs the correction based on the bounce characteristic value on condition that the interval time is smaller than a predetermined time. Claims 1 to 3 in which the correction unit corrects the interval time so that the timing of the bounce valley of the valve member after the end of energization of the pre-stage injection coincides with the energization start timing of the post-stage injection. The fuel injection control device according to any one of the above items. When the multi-stage injection is performed, a section determination unit that determines whether the energization start timing of the post-stage injection is in the down section or the up section of the bounce of the valve member after the end of energization of the pre-stage injection.
When it is determined that the energization start timing of the latter-stage injection is in the down section, a correction value for increasing the interval time or increasing the injection amount of the latter-stage injection is set as the bounce characteristic value, and the above-mentioned When it is determined that the energization start timing of the latter stage injection is in the ascending section, the correction value setting for setting the correction value for reducing the interval time or reducing the injection amount of the latter stage injection as the bounce characteristic value. Department and
The fuel injection control device according to any one of claims 1 to 4. An interval time setting unit that sets the interval time differently for each predetermined width, and
A calculation unit that calculates the injection start timing of the fuel injection valve after the start of energization of the post-stage injection when multi-stage injection is performed at the interval time set by the interval time setting unit.
With
The fuel injection control device according to claim 5, wherein the correction value setting unit sets the correction value based on the interval time when the injection start timing suddenly changes due to an increase or decrease of the interval time. .. The fuel injection control device (20) according to any one of claims 1 to 4, and the fuel injection control device (20).
A characteristic calculation device (70) that calculates the bounce characteristic value for each fuel injection valve under the state where the multi-stage injection is performed, and
With
The characteristic calculation device is
When the multi-stage injection is performed, a section determination unit that determines whether the energization start timing of the post-stage injection is in the down section or the up section of the bounce of the valve member after the end of energization of the pre-stage injection.
When it is determined that the energization start timing of the latter-stage injection is in the down section, a correction value for increasing the interval time or increasing the injection amount of the latter-stage injection is set as the bounce characteristic value, and the above-mentioned When it is determined that the energization start timing of the latter stage injection is in the ascending section, the correction value setting for setting the correction value for reducing the interval time or reducing the injection amount of the latter stage injection as the bounce characteristic value. Department and
Processing system equipped with. The characteristic calculation device is
An interval time setting unit that sets the interval time differently for each predetermined width, and
A calculation unit that calculates the injection start timing of the fuel injection valve after the start of energization of the post-stage injection when multi-stage injection is performed at the interval time set by the interval time setting unit.
With
The processing system according to claim 7, wherein the correction value setting unit sets the correction value based on the interval time when the injection start timing suddenly changes due to an increase or decrease of the interval time.

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