JP2018112120A - Fuel injection quantity control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel injection quantity control device capable of supplying an accurate fuel injection quantity by measuring an accurate valve closing time CT even during the operation of an internal combustion engine, and correcting an energizing time ET.SOLUTION: A fuel injection quantity control device includes a common rail filled with fuel, a fuel injection valve connected to the common rail, and an electronic control unit for controlling an injection quantity of the fuel injection valve. The electronic control unit executes energization for an energization time set to a magnet of the fuel injection valve in a coasting operation state in which an acceleration opening is zero, measures a first valve closing time from a time when the energization to the magnet is stopped to a time when a peak value of counter electromotive force is generated in the magnet, and corrects the energization time based on a valve closing time difference which is a difference between the first valve closing time and a reference value of a valve closing time. The energization time is set in a dead zone in which the first valve closing time is not affected by rail pressure of the fuel in the common rail.SELECTED DRAWING: Figure 8

Description

  The present invention relates to a fuel injection amount control device that adjusts a change in injection amount due to deterioration of a fuel injection valve (injector).

Conventionally, in the fuel injection amount control of an internal combustion engine, a technique is known that eliminates variation in the injection amount due to aging of the fuel injection valve and adjusts the injection amount within a specified value. The fuel injection amount of the fuel injection valve is defined as the energization time ET to the magnet of the solenoid valve and the valve closing time CT, which is the time from when the energization time ET ends until the armature of the fuel injection valve is seated on the valve seat. It is determined by the total time (valve opening time VOT). Here, the energization time ET is controlled by the electronic control unit. Further, the valve closing time CT varies depending on the lift amount of the armature. The valve closing time CT can be calculated by detecting the seating timing based on the back electromotive force generated in the magnet when the armature is seated on the valve seat, and measuring the time from when the energization time ET ends ( (See Patent Document 1).
In the conventional fuel injection amount control, the valve closing time CT is measured for each measurement condition of the combination of the rail pressure P and the energization time ET during engine operation (running), and the valve closing time corresponding to each measurement condition. CT data is collected on a two-dimensional map (two axes of rail pressure P and energization time ET). The energization time ET is corrected so that the valve opening time VOT, which is the total time of the energization time ET and the valve closing time CT, is constant. This correction of the energization time ET is referred to as VCC (Valve Closing Control). By performing VCC, even if the valve closing time CT changes, the valve opening time VOT becomes constant and a constant amount of fuel injection can be maintained.

JP2015-59427A

  Conventionally, when VCC (Valve Closing Control) is performed while the engine is in operation (running) as described above, a region with a low measurement frequency is generated on a two-dimensional map in which valve closing time CT data is accumulated. In such a region, there is a problem that the learning frequency when performing VCC decreases, and the accuracy of correcting the energization time ET decreases.

  The present invention has been made in order to solve the above-described problems. When performing VCC (Valve Closing Control), even if there is a region where the frequency of measurement of the valve closing time CT is small, the energization time is An object of the present invention is to obtain a fuel injection amount control device that improves the accuracy of ET correction and supplies an accurate fuel injection amount.

  A fuel injection amount control apparatus according to the present invention includes a common rail filled with fuel, a fuel injection valve connected to the common rail, and an electronic control unit that controls an injection amount of the fuel injection valve. In the inertial operation state with zero accelerator opening, the energization time set in the magnet of the fuel injection valve is energized, and after the energization to the magnet is stopped, the peak value of the back electromotive force is generated in the magnet The first valve closing time is measured, and the energizing time is corrected based on the valve closing time difference that is the difference between the first valve closing time and the reference value of the valve closing time. The energizing time depends on the rail pressure of the fuel in the common rail. The first valve closing time is set in a dead zone that is not affected.

  According to the fuel injection amount control device of the present invention, the valve is closed within the energization time ET, which is an inertia operating state where the accelerator opening is zero, and the dead time of the valve closing time CT with respect to the rail pressure P (fuel pressure). By measuring the time CT, an accurate valve closing time CT can be measured under stable measurement conditions and without being affected by the rail pressure P. Therefore, the energization time ET can be accurately corrected to correct the fuel injection amount of the fuel injection valve within the reference value. Further, when VCC (Valve Closing Control) is performed during traveling, even when there is a region where the measurement frequency of the valve closing time CT is low, the valve closing time CT is measured and diverted within the energization time ET that becomes a dead zone. Thus, it is possible to improve the accuracy of correcting the energization time ET and obtain a fuel injection amount control device that supplies an accurate fuel injection amount.

1 is a configuration diagram illustrating a common rail fuel injection amount control device according to Embodiment 1. FIG. 2 is a cross-sectional view of the fuel injection valve according to Embodiment 1. FIG. It is the figure which showed the relationship between the electric current value of the magnet of the solenoid valve which concerns on Embodiment 1, and the lift amount of an armature. 6 is a graph illustrating a data accumulation region of valve closing time CT according to the first embodiment. It is the figure which showed the relationship between the electricity supply time ET of the fuel injection valve which concerns on Embodiment 1, and valve closing time CT. It is explanatory drawing of an example shown about the relationship between the rail pressure P which concerns on Embodiment 1, energization time ET, and valve closing time difference (DELTA) CT. It is explanatory drawing of the other example shown about the relationship between the rail pressure P which concerns on Embodiment 1, energization time ET, and valve closing time difference (DELTA) CT. FIG. 5 is a correction control flow diagram of valve closing time CT in the dead zone according to the first embodiment. FIG. 10 is a correction control flow diagram of valve closing time CT in the dead zone according to the second embodiment.

Hereinafter, a fuel injection amount control apparatus according to the present invention will be described with reference to the drawings. The members and arrangements described below do not limit the present invention and can be variously modified within the scope of the gist of the present invention.
Moreover, in each figure, illustration of a detailed part is simplified or abbreviate | omitted suitably. In addition, overlapping descriptions are appropriately simplified or omitted.

Embodiment 1 FIG.
<Basic configuration of common rail fuel injection amount control device>
The fuel injection amount control apparatus according to Embodiment 1 of the present invention is applied to a so-called common rail fuel injection amount control apparatus.
FIG. 1 is a configuration diagram illustrating a common rail fuel injection amount control apparatus according to the first embodiment.
The common rail fuel injection amount control device includes a high pressure pump device 50 that pumps high pressure fuel, a common rail 1 that stores the high pressure fuel pumped by the high pressure pump device 50, and a high pressure fuel supplied from the common rail 1 as a diesel engine. A plurality of fuel injection valves 2 that supply the cylinders (hereinafter referred to as “engine 3”), and an electronic control unit 4 that executes operation control of the engine 3 and fuel injection amount control processing described later (in FIG. 1, “ ECU ”(noted as“ ECU ”) as main components.
Such a configuration itself is the same as the basic configuration of a well-known fuel injection amount control apparatus.

The high-pressure pump device 50 has a known configuration with the supply pump 5, the metering valve 6, and the high-pressure pump 7 as main components.
In such a configuration, the fuel in the fuel tank 9 is pumped up by the supply pump 5 and supplied to the high-pressure pump 7 through the metering valve 6. As the metering valve 6, an electromagnetic proportional control valve is used, and the energization amount thereof is controlled by the electronic control unit 4, so that the flow rate of fuel supplied to the high pressure pump 7, in other words, the discharge of the high pressure pump 7 The amount is to be adjusted.

A return valve 8 is provided between the output side of the supply pump 5 and the fuel tank 9 so that surplus fuel on the output side of the supply pump 5 can be returned to the fuel tank 9. .
The supply pump 5 may be provided separately from the high-pressure pump device 50 on the upstream side of the high-pressure pump device 50 or may be provided in the fuel tank 9.

  The fuel injection valve 2 is provided for each cylinder of the engine 3, and is supplied with high-pressure fuel from the common rail 1 and performs fuel injection by injection control by the electronic control unit 4. As the fuel injection valve 2 in the first embodiment, a so-called solenoid type is used.

  The electronic control unit 4 has, for example, a storage element (not shown) such as a RAM and a ROM, with a microcomputer having a known configuration as the center. Further, a circuit (not shown) for energizing and driving the fuel injection valve 2 and a circuit (not shown) for energizing and driving the metering valve 6 and the like are configured as main components. . In the first embodiment, a current monitor circuit 12 (indicated as “I-MONI” in FIG. 1) for detecting a counter electromotive current generated in the magnet 40 of the fuel injection valve 2 is provided. The detection output is supplied to a microcomputer (not shown) and is used for obtaining the closing timing of the solenoid valve 32 provided in the fuel injection valve 2 (details will be described later).

  In addition to the detection signal of the pressure sensor 11 that detects the pressure of the common rail 1 being input to the electronic control unit 4, various detection signals such as the engine speed, the accelerator opening, the outside air temperature, and the atmospheric pressure are input. 3 is used for operation control 3 and fuel injection amount control.

<Configuration of fuel injection valve 2>
FIG. 2 is a cross-sectional view of the fuel injection valve according to the first embodiment.
The known fuel injection valve 2 shown in FIG. 2 includes a fuel injection valve body 30, a nozzle body 31 attached to the distal end side of the fuel injection valve body 30, and the opposite side of the fuel injection valve body 30 that faces the nozzle body 31. And a solenoid valve 32 attached to the main body. A nozzle needle 33 is disposed in the nozzle body 31 so as to be slidable in the axial direction of the nozzle body 31. A long valve piston 34 is attached to the nozzle needle 33. The valve piston 34 is slidably disposed in the fuel injection valve main body 30 in the axial direction of the fuel injection main body 30.

  Further, the valve piston 34 is accommodated in the valve member 35 at the end opposite to the nozzle needle 33. A control chamber 36 in which the end of the valve piston 34 is arranged is defined in the valve member 35. The control chamber 36 communicates with a high pressure connection portion 37 to which fuel is supplied from the common rail. The high-pressure connection portion 37 further communicates with the flow path 38 and is connected to the nozzle sheet portion 39 between the nozzle body 31 and the tip of the nozzle needle 33 via the flow path 38. The nozzle needle 33 is biased toward the nozzle sheet portion 39 by a nozzle spring 33a. In addition, the control chamber 36, the flow path 38, the nozzle sheet | seat part 39, etc. which are connected to the high voltage | pressure connection part 37 are called the high pressure flow path of this invention.

  The solenoid valve 32 has a magnet 40 that is a solenoid coil, and an armature 41 made of a magnetic material is disposed on the lower end side of the magnet 40. The armature 41 is disposed so as to be slidable inside the cylindrical guide portion 42. On the lower end side of the armature 41, a circular valve seat 43 on which the lower end of the armature 41 is seated is formed. A valve spring 45 that urges the armature 41 toward the valve seat 43 is accommodated in the upper portion of the armature 41. An orifice 44 communicating with the control chamber 36 is opened at the center of the valve seat 43. The armature 41 moves upward so as to open the orifice 44 by energizing the magnet 40. A power connection 46 is further provided above the solenoid valve 32.

<Operation of fuel injection valve 2>
In the fuel injection valve 2, energization to the magnet 40 is stopped when no fuel is injected. The armature 41 is seated on the valve seat 43 by the valve spring 45 and the orifice 44 is closed. Then, the control chamber 36 is filled with high-pressure fuel from the common rail 1 and the nozzle seat portion 39 is similarly filled with high-pressure fuel. In this state, the nozzle needle 33 is driven by the resultant force of the pressure receiving area of the fuel acting on the control chamber 36 and the nozzle sheet portion 39 side, and the resultant force of the biasing force acting on the nozzle spring 33a. The nozzle sheet portion 39 is biased to the side (downward side) and is in a closed state. Therefore, fuel is not injected.

  When the magnet 40 is energized from the non-energized state of the magnet 40, the fuel injection valve 2 enters the injection state. At this time, the armature 41 is attracted by the magnetic force of the magnet 40 and contacts the lower surface of the magnet 40. As the armature 41 rises, the orifice 44 is opened, and the high-pressure fuel in the control chamber 36 flows out through the orifice 44 to a fuel tank (not shown). As a result, the pressure in the control chamber 36 decreases, and the upward force due to the high-pressure fuel charged on the nozzle sheet portion 39 side overcomes the downward force applied by the control chamber 36 and the nozzle spring 33a, and the nozzle needle Raise 33. Therefore, the fuel is injected from the tip of the nozzle body 31. And it will be in the state of the maximum injection rate by continuing electricity supply to the magnet 40. FIG.

<Valve closing time CT>
The energization time ET to the magnet 40 and the valve closing time CT during the injection of the fuel injection valve 2 will be described.
FIG. 3 is a diagram showing the relationship between the magnet current value of the solenoid valve and the armature lift amount according to the first embodiment.
As shown in FIG. 3, energization to the magnet 40 of the fuel injection valve 2 according to Embodiment 1 starts at an energization start time tp1 and stops at an energization end time tp2. At this time, the current value of the magnet 40 rapidly increases with the passage of time from the energization start time tp1, and once decreases to a certain peak value.
Thereafter, the current value is substantially constant until the energization end time tp2, and changes from the energization end time tp2 toward zero as time elapses. Then, after the energization waveform of the current value reaches zero, a convex energization waveform that peaks in a relatively short time after a lapse of some time and then becomes zero in a relatively short time appears.

At this time, the armature 41 of the solenoid valve 32 starts being lifted by being pulled by the magnet 40 at the lift start time tp3 at a slight interval from the energization start time tp1. The armature 41 sucked by the magnet 40 stops at the maximum lift position.
When the magnetic force of the magnet 40 disappears at the energization end time tp2, the armature 41 descends toward the valve seat 43. Then, the armature 41 is seated on the valve seat 43 at the seating time ta1.

The convex energization waveform that re-appears in the energization waveform of the current value that has once decreased after the energization is completed indicates the counter electromotive current generated in the magnet 40 when the armature 41 of the solenoid valve 32 is seated on the valve seat 43 and closed. It has been done. The peak is known to correspond to the timing at which the armature 41 is seated on the valve seat 43, and in the example of FIG. 23, is the time of the seating time ta1. That is, the timing at which the armature 41 is seated on the valve seat 43 is the point at which the maximum counter electromotive force is generated.
In FIG. 3, the time interval between the energization end time tp2 and the seating time ta1 is expressed as the valve closing time CT1. The valve closing time CT1 indicates the valve closing time CT of a new center product that serves as a reference, and serves as a reference value for the valve closing time CT at the time of manufacture. The new center product is a reference product having a valve closing time CT within a reference range in the unused fuel injection valve 2.

In the first embodiment of the present invention, the above-described counter electromotive current is detected by the current monitor circuit 12, and the detection signal is input to a microcomputer (not shown) constituting the electronic control unit 4. Then, the valve closing time CT of the fuel injection valve 2 can be acquired by the difference between the energization end time tp2 and the seating time ta1.
The above-described times tp1, tp2,... Are determined based on the timing at which the piston (not shown) in the engine 3 is at the top dead center.

Next, an example will be described in which the valve closing time CT of the fuel injection valve 2 is deviated from the reference value of the valve closing time CT1 of the new center product due to deterioration over time.
A seating time ta2 indicated by a broken line in FIG. 3 indicates an energization waveform of the fuel injection valve 2 in which the valve closing time CT is deviated from the reference value of the new center product.
That is, the armature 41 is seated on the valve seat 43 from the maximum lift position over a time longer than the reference valve closing time CT1. The seating time ta2 at this time is shifted to the right in FIG. 3 from the standard seating time ta1 of the new center product. The valve closing time CT2 at this time is represented by a time interval between the energization end time tp2 and the seating time ta2, and is longer than the valve closing time CT1.
The cause of the aging deterioration in which the valve closing time CT becomes long can be an increase in the lift amount of the armature 41, an increase in the operating resistance of each sliding portion, and the like.
Here, the difference between the valve closing time CT1 which is the reference value of the new central product of the valve closing time CT and the valve closing time CT2 deviated from the reference value due to deterioration over time is defined as a valve closing time difference ΔCT.

The valve opening time VOT1 of the new center product is represented by the time from the lift start time tp3 at which the armature 41 starts to lift to the seating time ta1. Further, the valve opening time VOT2 of the fuel injection valve 2 deteriorated from the reference value of the new central product is represented by the time from the lift start time tp3 when the armature lift starts to the seating time ta2.
In the case shown in FIG. 3, the energization time ET is common to the two fuel injection valves 2, but due to the difference in the valve closing time CT, a difference occurs between the valve opening time VOT1 and the valve opening time VOT2, and the fuel injection amount increases. It will be.

<Correction control of energizing time ET by VCC (Valve Closing Control) during driving>
VCC (Valve Closing Control) during running measures the valve closing time CT for each measurement condition of the combination of the rail pressure P and the energization time ET, and the data of the valve closing time CT corresponding to each measurement condition is two-dimensional. (Two axes of rail pressure P and energization time ET) are collected on the map.
Then, the energization time ET is corrected so that the valve opening time VOT, which is the total time of the energization time ET and the valve closing time CT, becomes constant. Even when the valve closing time CT under the operating condition for performing VCC changes, the valve opening time VOT becomes constant and a constant amount of fuel injection can be maintained.

VCC is to accumulate data of the measured closed time CT P _{(corresponding} to the second valve closing time of the present invention) was calculated and the average value from the time of travel, the correction of the energizing time ET. Therefore, although the response is slow, the median value of the displacement of the valve closing time CT due to deterioration can be detected with high accuracy, and the energization time ET can be corrected.
The running VCC measures the valve closing time CT during the operation of the engine 3, so the influence of the changing rail pressure P (fuel pressure) of the fuel in the common rail, injection pattern, injection timing, fuel temperature, etc. receive. However, to ensure accuracy by accumulating data in the valve closing time CT _P measured, correct the energizing time ET is compared with the reference value of the valve closing time CT of their mean value and example new central article .

FIG. 4 is a graph illustrating a data accumulation region of the valve closing time CT according to the first embodiment.
When storing the data in the valve closing time CT _P includes energizing time ET to the magnet 40, as measured rail pressure P parameters, for example providing the 9 divided data storage region, as shown in FIG. When the data of the closed time CT _P is a predetermined number stored in the data storage for each region, the average value thereof is calculated. The average value of the closing time CT _P is compared with a reference value, the valve closing time difference △ CT _P is calculated by subtracting the reference value from the average value of the closing time CT _P. The opening time VOT corrects the length of the energizing time ET to be constant based on the calculated closing time difference △ CT _P.
That is, if the corrected short energizing time ET to opening time VOT is constant average value of the measured closed time CT _P is longer than the reference value of the valve closing time CT of new central article Reduce fuel injection. Further, when the corrected longer energizing time ET to opening time VOT is constant average value of the measured closed time CT _P is shorter than the reference value of the valve closing time CT of new central article Increase fuel injection.

Typical examples of the deterioration phenomenon of the fuel injection valve 2 include wear due to the use of the nozzle seat portion 39 on which the nozzle needle 33 is seated and an increase in the lift amount of the armature 41 of the solenoid valve (not shown). be able to.
The wear of the nozzle seat portion 39 causes an increase in the valve opening pressure due to an increase in the seat diameter, thereby causing a delay in the injection timing and a decrease in the fuel injection amount.
The increase in the lift amount of the armature 41 of the solenoid valve 32 is caused by wear of the valve seat 43 with which the lower end portion of the armature 41 abuts. The increase in the lift amount of the armature 41 extends the valve closing time CT from the end of energization of the fuel injection valve 2 until the armature is seated on the valve seat 43, leading to an increase in the fuel injection amount. .

  The correction control of the energization time ET based on VCC, which is assumed in the first embodiment, corrects the deviation from the original fuel injection amount due to the change in the lift amount of the armature 41 among the above-mentioned in the control principle. is there.

<Relationship between rail pressure P, energization time ET, and valve closing time CT>
Here, the relationship between the energization time ET and the valve closing time CT when the fuel injection valve 2 is filled with fuel by changing the rail pressure P (fuel pressure) will be described with reference to FIG.
FIG. 5 is a diagram showing the relationship between the energization time ET and the valve closing time CT of the fuel injection valve according to the first embodiment.
FIG. 5 shows the energization time ET to the magnet 40 of the fuel injection valve 2 on the horizontal axis, and the valve closing time that is the time from when the energization time ET ends until the armature 41 is seated on the valve seat 43 on the vertical axis. CT is shown.
Further, the fuel pressure (rail pressure P) charged in the fuel injection valve 2 is measured by dividing it into a plurality of patterns. In FIG. 5, the range of the valve closing time CT when the rail pressure P is 40 MPa is indicated by a solid line, the range of the valve closing time CT when the rail pressure P is 80 MPa is indicated by a broken line, and the range when the rail pressure P is 120 MPa. The range of the valve closing time CT is indicated by a chain line.

  In the fuel injection valve 2 according to the first embodiment, as shown in FIG. 5, the valve closing time CT has a correlation with the fuel pressure (rail pressure P) in the region where the energization time ET is longer than 400 μs. Yes. That is, the higher the fuel pressure, the shorter the valve closing time CT.

  This is because when the fuel pressure is increased, the valve member 35 of the fuel injection valve body 30 is slightly expanded outwardly and deformed by the pressure of the fuel filled in the control chamber 36. Then, the valve seat 43 above the control chamber 36 moves relatively upward. Therefore, the lift amount (stroke length) until the armature 41 is seated on the valve seat 43 from the lower surface of the magnet 40 is shortened, and the valve closing time CT is shortened.

  If the energization time ET is increased in the region where the energization time ET is relatively short, 200 to 400 μs, with respect to the region where the energization time ET is relatively long, the valve closing time CT is the maximum value for each fuel pressure line. It increases to Max (ET = about 230 μs). Thereafter, the valve closing time CT starts to decrease from the maximum value Max in a state where the lines of the fuel pressures (each rail pressure P) overlap to some extent, and then decreases to the minimum value Min (energization time ET = about 350 μs). When the energization time ET increases beyond 400 μs, it is affected by the fuel pressure, and the lines of the valve closing times CT at the fuel pressures are scattered and do not overlap. That is, in the region where the energization time ET is relatively short, which is 230 μs or more and 350 μs or less, there is a region where the correlation between the valve closing time CT and the change in fuel pressure (rail pressure P) is low. The region of the energization time ET is defined as a dead zone of the valve closing time CT with respect to the rail pressure P.

In the region where the energization time ET is relatively short, 200 to 400 μs, when the energization time ET is shorter than 230 μs, the armature 41 falls without reaching the lower surface of the magnet. When the energization time ET is about 230 μs, the dwell time of the armature 41 becomes the maximum and the valve closing time CT shows the maximum value.
When the energization time ET is longer than ET = 230 μs, the armature 41 collides with the armature 41 and the lower surface of the magnet 40 in a compressed state, and rebounds by the repulsive force of the fuel and sits on the valve seat 43. To do. Therefore, the armature 41 moves to the valve seat 43 with the initial speed applied. Therefore, the valve closing time CT is gradually shortened as the energization time ET increases.

  When the energization time ET is in a relatively short region of 230 μs or more and 350 μs or less, the pressure of the fuel filled in the control chamber 36 is reduced by opening the nozzle needle 33. Therefore, the deformed state in which the valve member 35 and the like of the fuel injection valve body 30 are expanded is eliminated, and the valve seat 43 provided above the control chamber 36 returns to the position before the pressure is applied. Then, the lift amount (stroke length) until the armature 41 is seated on the valve seat 43 from the lower surface of the magnet 40 returns to the length before the fuel pressure is applied, the valve closing time CT and the fuel pressure (rail pressure P). ) Correlation with change is low.

  Further, when the energization time ET is longer than 400 μs, the armature 41 once contacts the lower surface of the magnet 40 and sits on the valve seat 43 after the magnet 40 is de-energized. In the region of the energization time ET, the pressure of the fuel filled in the control chamber 36 is restored, and the valve member 35 and the like of the fuel injection valve body 30 are in a deformed state. For this reason, as described above, the valve closing time CT is affected by the lift amount (stroke length) of the armature 41 and changes depending on the fuel pressure (rail pressure P).

  Therefore, in the region where the energization time ET is relatively short, ET = 230 to 350 μs (dead zone), the correlation between the valve closing time CT and the change in the fuel pressure (rail pressure P) is low. Then, the valve closing time difference ΔCT, which is the difference between the valve closing time CT in the dead zone and the reference value of the valve closing time CT of the new center product, is also less correlated with the change in the fuel pressure (rail pressure P), and the dead zone. The valve closing time difference ΔCT can be calculated uniquely.

<Correlation with valve closing time difference △ CT other than dead zone>
Here, regarding the valve closing time difference ΔCT which is the difference between the valve closing time CT in the dead zone and the reference value of the valve closing time CT of the new center product, the correlation with the measurement points other than the dead zone will be described with reference to FIGS. explain.
FIG. 6 is an explanatory diagram of an example illustrating the relationship among the rail pressure P, the energization time ET, and the valve closing time difference ΔCT according to the first embodiment.
FIG. 7 is an explanatory diagram of another example showing the relationship between the rail pressure P, the energization time ET, and the valve closing time difference ΔCT according to the first embodiment.

In FIG. 6, the horizontal axis represents the valve closing time difference ΔCT belonging to the dead zone where the rail pressure P is 120 MPa and the energization time ET is 235 μs. In addition, the vertical axis indicates a 5-point valve closing time difference ΔCT in which the rail pressure P and the energization time ET are different from the measurement conditions on the horizontal axis.
Here, 5 points means that when the rail pressure P is 180 MPa and the energization time ET is 760 μs, the rail pressure P is 120 MPa and the energization time ET is 540 μs, the rail pressure P is 80 MPa, and the energization time ET is 630 μs. When the rail pressure P is 80 MPa and the energization time ET is 250 μs, the rail pressure P is 30 MPa and the energization time ET is 560 μs, respectively.

In FIG. 7, the horizontal axis represents the valve closing time difference ΔCT belonging to the dead zone where the rail pressure P is 80 MPa and the energization time ET is 250 μs. In addition, the vertical axis indicates a 5-point valve closing time difference ΔCT in which the rail pressure P and the energization time ET are different from the measurement conditions on the horizontal axis.
Here, as in the example of FIG. 6, 5 points means that when the rail pressure P is 180 MPa and the energization time ET is 760 μs, when the rail pressure P is 120 MPa and the energization time ET is 540 μs, the rail pressure P is 80 MPa. When the energization time ET is 630 μs, the rail pressure P is 80 MPa and the energization time ET is 250 μs, and when the rail pressure P is 30 MPa and the energization time ET is 560 μs, respectively.

  Then, from these two examples, the valve closing time difference ΔCT measured in the dead zone has a very high correlation with the valve closing time difference ΔCT measured under other measurement conditions. This means that by measuring the valve closing time difference ΔCT in the dead zone, substantially the same valve closing time difference ΔCT is obtained even under other measurement conditions. Therefore, even if the valve closing time difference ΔCT is measured under various conditions, accumulated, and the average value is not calculated, the valve closing time difference ΔCT only in the dead zone can be measured to obtain an accurate valve closing time difference ΔCT under the measurement conditions in the entire area. Can be obtained.

<Measurement of △ CT during inertial driving>
In the running mode VCC (energization time ET correction control) according to the first embodiment, the valve closing time CT is measured during the operation of the engine 3 as in the prior art. Fuel pressure), injection pattern, injection timing, fuel temperature, etc.
Therefore, the electronic control unit 4 according to the first embodiment measures and stabilizes the rail pressure P (fuel pressure), the injection pattern, the injection timing, etc., when the engine 3 is in the inertial operation state of the vehicle body with the accelerator opening being zero. When the condition is stable, CT measurement is executed.
Hereinafter, CT measurement during inertial operation and a method for reflecting the valve closing time difference ΔCT to VCC will be described.

The electronic control unit 4 corresponds to the fuel injection amount for each region of the combination of the fuel injection amount to be learned in the inertia operation state with the accelerator opening being zero and the rail pressure P (fuel pressure) of the fuel in the common rail. A short energization time ET is set and minute fuel injection is performed.
Then, fuel injection by the micro injection amount, that is, micro injection is executed about several tens of times. Next, the frequency component of the engine speed fluctuation that occurs during the minute injection is extracted as an average value. Such processing is performed for each fuel injection valve 2.
Then, based on the frequency component in which the engine speed fluctuates, an estimated value (estimated injection amount) of the fuel amount that would have been actually injected at that time is calculated.
That is, an estimated value (estimated injection amount) of the fuel amount is calculated on the two-dimensional map while changing the energization time ET and the rail pressure P as measurement parameters.

When the estimated injection amount calculated for the first time exceeds the threshold value defined and defined for each rail pressure P, the estimated injection amount decreases toward the predetermined threshold value and almost converges within the specified threshold value. As described above, the acquisition of the estimated injection amount is repeated while the energization time ET in the minute injection is reduced.
In addition, when the estimated injection amount calculated for the first time is lower than the threshold value defined and defined for each rail pressure P, the estimated injection amount increases toward the predetermined threshold value and falls within the specified threshold value. The acquisition of the estimated injection amount is repeated while the energization time ET in the minute injection is increased so as to almost converge.
Then, the difference between the energization time ET required to obtain the estimated injection amount when converged to the predetermined threshold and the reference energization time is stored as a difference energization time learning value ΔET in each region of the energization time learning value map. Accumulated.

  Here, the reference energization time is the energization time ET measured immediately before the start of use before the fuel injection valve 2 deteriorates, and the energization time corresponding to the rail pressure P and the fuel injection amount for each fuel injection valve 2. The ET is mapped (hereinafter referred to as “reference energization time map” for convenience) and stored in advance in the electronic control unit 4.

When fuel injection is performed under the conditions (rail pressure P and fuel injection amount) for which the difference energization time learning value ΔET is acquired, the reference energization time is determined by the average value of the accumulated difference energization time learning value ΔET. The corrected time is used as the energization time ET to correct the deviation between the fuel injection amount and the energization time ET.
The correction of the fuel injection amount in this inertial operation state is defined as ZFC (Zero Fuel-quantity Calibration).
The method for obtaining the correction amount in the fuel injection amount correction control is not necessarily limited to the above-described method, and as a result, the energization time ET of the fuel injection valve 2 is extended or shortened according to the correction amount. If it is, it is possible to apply this invention similarly.

The fuel injection amount control apparatus according to Embodiment 1 performs CT measurement simultaneously with performing the ZFC (Zero Fuel-quantity Calibration).
The fuel injection amount correction (ZFC) in the inertial operating state is a correction accompanied by a minute fuel injection in which a short energization time ET is set. Therefore, the valve closing time CT corresponding to the energization time ET is measured and learned. Is possible.
Then, when the fuel injection amount correction (ZFC) is performed, in the dead zone of the valve closing time CT with respect to the rail pressure P (region of the short energization time ET), the closing of the new central product with respect to the valve closing time CT stored in advance is performed. The valve time difference ΔCT can be calculated.
Then, as described above, by measuring the valve closing time difference ΔCT only in the dead zone, an accurate valve closing time difference ΔCT can be obtained over the entire measurement conditions of the other energization time ET and rail pressure P. Therefore, the CT measurement in the dead zone and the calculated valve closing time difference ΔCT can be used in the region of the energization time ET and the rail pressure P other than the VCC dead zone. That is, the entire data storage area of the valve closing time CT in FIG. 4 can be updated.

FIG. 8 is a correction control flowchart of the valve closing time CT in the dead zone according to the first embodiment.
First, when the operation of the vehicle is started, the electronic control unit 4 determines whether or not the coolant temperature has exceeded 80 ° C. in Step 1. When the water temperature exceeds 80 ° C., it is determined that the kinematic viscosity of the fuel around the magnet 40 of the fuel injection valve 2 is stable, and the process proceeds to Step 2. If the water temperature is 80 ° C. or lower, the process returns to Step 1.

In step 2, it is determined whether or not the vehicle speed exceeds 60 km / h. If the vehicle speed exceeds 60 km / h, it is determined that inertial traveling with zero accelerator opening is possible, and the process proceeds to step 3. If the vehicle speed is 60 km / h or less, the process returns to step 1.
In step 3, it is determined whether or not the accelerator opening of the accelerator pedal signal has become zero. When the accelerator opening becomes zero, the routine proceeds to step 4. When the accelerator opening is not zero, the process returns to step 1.

In step 4, it is determined whether or not more than 3 seconds have elapsed since the accelerator opening of the accelerator pedal signal became zero in step 3. If more than 3 seconds have elapsed, it is determined that inertial running will continue, and the process proceeds to step 5. If the accelerator is turned on within 3 seconds, the process returns to step 1.
If it is determined in step 4 that the inertial running is continued, the electronic control unit 4 performs the ZFC (Zero Fuel-quantity Calibration), and corrects the fuel injection amount with a minute fuel injection with a short energization time ET set. To do.
In step 5, the number of learning times N of ZFC is counted. This ZFC learning is synonymous with the number of learning times of the valve closing time CT because it is measured so as to include the valve closing time CT of the dead zone as shown in the next section. The learning frequency N of ZFC is stored in the electronic control unit 4 even after the engine 3 is stopped.
In step 6, the rail pressure P is set to the pressure learned this time.

  Next, in step 7, in order to perform CT measurement in the dead zone, a lower limit energization time ET1 and an upper limit energization time ET2 for learning this time are set. The lower limit energization time ET1 and the upper limit energization time ET2 of the energization time ET are set as dead zone regions of the energization time ET that have a low influence on the valve closing time CT with respect to changes in the rail pressure P. As the dead zone, for example, when the energization time ET shown in FIG. 5 is 230 μs or more and 350 μs or less, the valve closing time CT is measured at a straight line portion where the lines of the rail pressures P are overlapped. This is because by measuring the valve closing time CT within the dead zone of the valve closing time CT with respect to the rail pressure P as described above, the accurate valve closing time CT can be measured without being influenced by the rail pressure P. .

Proceeding to Step 8, the rail pressure P set in Step 6 and the energization time ET that becomes the lower limit energization time ET1 set in Step 7 are output, and the valve closing time CT _F in the dead zone for each cylinder (first of the present invention) Corresponding to one valve closing time).
The process proceeds to step 9 to set the energizing time ET from energizing time ET of measuring the closing time CT _F in step 8, for example + 5 .mu.s extended to.

Next, in step 10, it is determined whether or not the energization time ET set in step 9 has reached the upper limit energization time ET2 set in step 7. When it does not reach the upper limit conduction time ET2, the process returns to step 8, to measure the closing time CT _F. If you run out energization time ET2, the process proceeds to step 11, the process proceeds to step 12 to calculate the average value CT _N closing and measurement time CT _F.

In step 12, it is determined whether or not the learning count N of the valve closing time CT is 2 times or more. If learning number N more than once, the process proceeds to step 13, the average value _{CT N-1} of the previous closing time average value CT _N of this closing time CT _F calculated in step 11 _{CT F-1} the subtracted to calculate the valve closing time difference △ CT _F in the dead zone. If the learning number N is not two times or more, the process returns to step 1.

Next, in step 14, and the valve closing time difference △ CT _P which is measured in the past stored in the running time of the VCC, averages the valve closing time difference △ CT _F of the calculated dead zone at step 13, the valve closing time difference △ to calculate the CT _a. Here, to calculate the valve closing time difference △ CT _P in a plurality of regions and a rail pressure P and the energizing time ET as measured parameters during running of VCC, the for all the areas, calculated in this dead zone closed The time difference ΔCT _F can be effectively added.
The reason for this is that, as described above in <Correlation with valve closing time difference ΔCT other than dead zone>, the valve closing time difference ΔCT _F measured in the dead zone is equal to the valve closing time difference ΔCT measured under other measurement conditions. This is because the correlation is very high. Therefore, even for a region closed time difference △ CT _P is not stored in the VCC at the time of traveling, it is possible to effectively adds the closing time difference △ CT _F calculated in the dead zone.

The process proceeds to step 15, the valve closing time difference △ CT _A calculated in step 14 in the case of positive (greater than the reference value of the valve closing time CT) causes the energizing time ET short correction to decrease the fuel injection amount. Moreover, the valve closing time difference △ CT _A calculated in step 14 in the case of negative (less than the reference value of the valve closing time CT1) is the energization time ET longer corrected to increase the fuel injection quantity.

Note that, in step 8-10, a plurality of times while increasing little by little in the dead zone the energizing time ET, has been averaged measured closing time CT _F, sets a plurality of rail pressure P in the step 6 (e.g. , etc. 120Mpa and 80MPa according to Figure 5-7) respectively to measure the closing time CT _F may be averaged.

In step 14, the valve closing time difference △ CTp which is measured in the running time of the VCC, the valve closing time difference of the calculated dead band △ a CT _F averaged at step 13, has been calculated closing time difference △ CT _A valve closing time difference between dead zone calculated in step 13 △ using CT _F only, may be corrected length of the energizing time ET in step 15 as the absolute value decreases the △ CT _F.

<Effect>
According to the fuel injection amount control apparatus according to the first embodiment, the engine is in the inertial operating state with zero accelerator opening and within the energization time ET that is the dead zone of the valve closing time CT with respect to the rail pressure P (fuel pressure). By measuring the valve closing time CT, an accurate valve closing time CT can be measured under stable measurement conditions and without being affected by the rail pressure P. Therefore, the energization time ET can be accurately corrected to adjust the valve opening time VOT, and the fuel injection amount of the fuel injection valve 2 can be corrected within the reference value.
In addition, by measuring the valve closing time CT within the energization time ET, which is a dead zone of the valve closing time CT with respect to the rail pressure P (fuel pressure), the measurement conditions of the rail pressure P and the energization time ET other than the measurement points are also omitted. It is possible to predict the valve closing time difference ΔCT having the same tendency. For this reason, even in the region of rail pressure P and energization time ET in which the valve closing time CT is not accumulated by VCC during travel, the valve closing time difference ΔCT in the dead zone is diverted to adjust the valve opening time VOT by correcting the energization time ET. The fuel injection amount of the fuel injection valve 2 can be corrected within the reference value.
Furthermore, since the CT measurement in the dead zone is simultaneously performed when adjusting the fuel injection amount by the ZFC provided conventionally, the learning frequency of the valve closing time CT can be sufficiently ensured.

Embodiment 2. FIG.
In the first embodiment, FIG. 8 is a correction control flow chart of the valve closing time CT in the dead zone. In step 12, when the number N of learning times of the valve closing time CT is two or more, the process proceeds to step 13 to close the valve in the dead zone. The time difference ΔCT _F was calculated. In contrast, in the second embodiment, the average value CT _N and compared with the reference value of the valve closing time CT direct new central article closing time difference △ CT _F in the valve closing time CT _F calculated in step 11 The points to be calculated are different.
Since the configuration of the other fuel injection amount control device is the same as that of the first embodiment, description thereof is omitted.

<Control for correcting valve closing time CT in dead zone of valve closing time CT with respect to rail pressure P>
FIG. 9 is a correction control flowchart of the valve closing time CT in the dead zone according to the second embodiment.
The correction control flow of the valve closing time CT in the dead zone according to the second embodiment is the same as the correction control flow described in FIG. 8 according to the first embodiment from step 1 to step 11.
Therefore, step 12 and subsequent steps will be described.
In step 12, the reference value of the valve closing time CT of the new central product is subtracted from the valve closing time CT _F measured in step 8 or the average value CT _N of the valve closing time CT _F calculated in step 11. calculating the closing time difference △ CT _F is the difference.
In step 13, the valve closing time difference △ CTp calculated by the travel time of the VCC, the valve closing time difference of the dead zone which is calculated in step 12 △ CT and _F averaged to calculate the valve closing time difference △ CT _A.

Then the process proceeds to step 14, the valve closing time difference △ CT _A calculated in step 13 in the case of positive (greater than the reference value of the valve closing time CT) causes the energizing time ET short correction to decrease the fuel injection amount. Moreover, the valve closing time difference △ CT _A calculated in step 13 in the case of negative (less than the reference value of the valve closing time CT) is the energizing time ET longer corrected to increase the fuel injection quantity.

In step 13, as in the first embodiment, the valve closing time difference calculated by the travel time of the VCC △ CT _P, closing time difference of the dead zone, which is calculated in step 12 △ a CT _F averages, closing time difference ΔCT _A is calculated, but the length of the energization time ET in step 14 is set so that the absolute value of the valve closing time difference ΔCT _F is reduced using only the dead-zone valve closing time difference ΔCT _F calculated in step 12. May be corrected.

<Effect>
According to the fuel injection amount control apparatus according to the second embodiment, in addition to the effect according to the first embodiment, not stored learning frequency N of the average value CT _N closing time CT _F in dead zone more than once even, it is possible to calculate the valve closing time difference △ CT _F by comparing the reference value of the average value CT _N and new central parts of the valve closing time CT for the first time, early implement correction of the energizing time ET It becomes possible to do.

1 common rail, 2 fuel injection valve, 3 engine, 4 electronic control unit, 5 supply pump, 6 metering valve, 7 high pressure pump, 8 return valve, 9 fuel tank, 11 pressure sensor, 12 current monitor circuit, 30 fuel injection valve Main body, 31 Nozzle body, 32 Solenoid valve, 33 Nozzle needle, 33a Nozzle spring, 34 Valve piston, 35 Valve member, 36 Control chamber, 37 High pressure connection part, 38 Flow path, 39 Nozzle seat part, 40 Magnet, 41 Armature, 42 Guide section, 43 Valve seat, 44 Orifice, 45 Valve spring, 46 Power supply connection section, 50 High-pressure pump device, CT valve closing time, ET energization time, ET1 lower limit energization time, ET2 upper limit energization time, N learning frequency, P rail Pressure, VOT valve opening time, ΔCT valve closing time difference, ΔET difference energization time learning value.

Claims (10)

A common rail filled with fuel, a fuel injection valve connected to the common rail, and an electronic control unit for controlling an injection amount of the fuel injection valve,
The electronic control unit is
In the inertial operation state with zero accelerator opening, the energization time set for the magnet of the fuel injection valve is energized, and the energization to the magnet is stopped until the peak value of the back electromotive force is generated in the magnet Measuring the first valve closing time, and correcting the energization time based on a valve closing time difference which is a difference between the first valve closing time and a reference value of the valve closing time,
The fuel injection amount control device, wherein the energization time is set in a dead zone in which the first valve closing time is not affected by the rail pressure of the fuel in the common rail. The electronic control unit is
Calculating the valve closing time difference as a value obtained by subtracting the reference value from the first valve closing time;
If the valve closing time difference is positive, correct the energization time to be shorter,
The fuel injection amount control device according to claim 1, wherein when the valve closing time difference is negative, correction is made so that the energization time becomes longer. The electronic control unit is
The first valve closing time is measured a plurality of times within the dead zone energization time, and an average value of the measured first valve closing times is calculated,
Calculate the valve closing time difference as a value obtained by subtracting the reference value from the average value,
If the valve closing time difference is positive, correct the energization time to be shorter,
The fuel injection amount control device according to claim 1, wherein when the valve closing time difference is negative, correction is made so that the energization time becomes longer. The electronic control unit is
The first valve closing time is measured a plurality of times within the energization time of the dead zone, and an average value of a plurality of measured first valve closing times is continuously calculated a plurality of times,
Calculated as a value obtained by subtracting the previous average value from the current average value calculated continuously for the valve closing time difference,
If the valve closing time difference is positive, correct the energization time to be shorter,
The fuel injection amount control device according to claim 1, wherein when the valve closing time difference is negative, correction is made so that the energization time becomes longer. The electronic control unit is
In a traveling operation state having an accelerator opening, the magnet of the fuel injection valve is energized for a set energizing time, and after the energization to the magnet is stopped, a peak value of back electromotive force is generated in the magnet. Measure the second valve closing time until
The valve closing time difference is calculated as an average value of a value obtained by subtracting the reference value from the first valve closing time and a value obtained by subtracting the reference value from the second valve closing time;
If the valve closing time difference is positive, correct the energization time to be shorter,
The fuel injection amount control device according to claim 1, wherein when the valve closing time difference is negative, correction is performed so that the energization time becomes longer.   The fuel injection amount control device according to any one of claims 1 to 5, wherein the first valve closing time is measured a plurality of times under a condition in which the energization time in the dead zone is different.   The fuel injection amount control device according to any one of claims 1 to 6, wherein the first valve closing time is measured a plurality of times under different conditions of the rail pressure in the dead zone.   8. The dead zone energization time is defined as a time between a maximum value and a minimum value of the first valve closing time with respect to a change in the energization time. Fuel injection amount control device.   The fuel injection amount control device according to claim 1, wherein the dead zone energization time includes a value of 230 μs to 350 μs. The electronic control unit is
The fuel injection amount control device according to claim 1, wherein energization of the fuel injection valve is performed for each of the fuel injection valves.

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