JP7213627B2 - internal combustion engine controller - Google Patents

Description

The present invention relates to an internal combustion engine control system.

With the tightening of exhaust gas regulations in recent years, there is a demand for a reduction in the minimum injection amount of fuel injection devices. One of the challenges in reducing the minimum injection amount is to reduce variations in the injection amount due to individual differences in fuel injection devices. As a technique for reducing this variation, for example, the technique described in Patent Document 1 has been proposed. The technique disclosed in Patent Document 1 extracts a specific frequency component from a detection signal of the terminal voltage immediately after de-energization of the solenoid of the fuel injection device, and based on the specific frequency component, the valve body of the fuel injection device moves to the valve seat. to estimate the seating timing. Then, based on the estimated seating timing, control is performed so that the actual valve opening time of the fuel injection device converges to the required valve opening time.

In the technique disclosed in Patent Document 1, since the characteristics of the fuel injection device are reflected in the seating timing, the seating timing is detected and feedback control is performed based on the detected seating timing. This makes it possible to correct individual differences in fuel injection devices. In particular, it is considered that the effect is great when the operating state of the internal combustion engine is constant. On the other hand, if the operating state of the internal combustion engine changes transiently, it is conceivable that the feedback may not be able to follow the change.

JP 2014-234922 A

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide an internal combustion engine control system capable of appropriately controlling a fuel injection device even when the operating state of the internal combustion engine changes.

In order to solve the above problems, an internal combustion engine control device according to a first aspect of the present invention is an internal combustion engine control device for controlling a fuel injection device of an internal combustion engine, wherein the internal combustion engine control device comprises a CPU, The CPU comprises a measurement unit for measuring the acceleration of the valve body of the fuel injection device when the fuel injection device is driven, and a first measurement unit for measuring the voltage or current applied to the fuel injection device based on individual differences in the acceleration. and a correction unit that corrects the physical quantity.

According to the present invention, it is possible to provide a control device for a fuel injection device that can appropriately control the fuel injection device even when the operating state of the internal combustion engine changes.

1 is a schematic diagram showing an internal combustion engine control apparatus according to a first embodiment and an internal combustion engine having a fuel injection device to be controlled; FIG. 2 is a cross-sectional view showing an example of the structure of fuel injection device 116 in the first embodiment; FIG. 3 is a circuit diagram illustrating a specific example of the configuration of a control circuit 300 that controls fuel injection device 116 in the first embodiment; FIG. 4 is a timing chart for explaining control of fuel injection device 116 by control device 300 in the first embodiment. 4 is a timing chart for explaining control of fuel injection device 116 by control device 300 in the first embodiment. It is a schematic diagram explaining PID feedback control. 5 is a graph illustrating changes in the current Is of the solenoid 203 when the pulse width Ti is changed in a plurality of ways, and displacement H of the valve body 204 when the pulse width Ti is changed in a plurality of ways. 4 is a graph showing an example of a Ti-a curve of the fuel injection device 116; 4 is a graph for explaining changes in the Ti-a curve due to individual differences in the fuel injection device 116. FIG. 7 is a graph for explaining a method of detecting the valve closing timing tb of the valve body 204 from the timing of the inflection point of the voltage Vs. In the first embodiment, based on the deviation Δa from the standard value of the acceleration a and the standard characteristic data (Ti-a curve CtiaS) stored in the standard characteristic data storage unit 21, the target fuel injection device 1 is a schematic diagram illustrating a method of identifying a unique Ti-a curve; FIG. In the first embodiment, based on the deviation Δa from the standard value of the acceleration a and the standard characteristic data (Ti-a curve CtiaS) stored in the standard characteristic data storage unit 21, the target fuel injection device 1 is a schematic diagram illustrating a method of identifying a unique Ti-a curve; FIG. FIG. 4 is a schematic diagram illustrating a method of correcting a pulse width Ti according to a Ti-a curve in the first embodiment; FIG. 2 is a schematic diagram showing an internal combustion engine control apparatus according to a second embodiment and an internal combustion engine having a fuel injection device to be controlled; A graph (Ti-Q curve) showing the relationship between the pulse width Ti and the injection amount Q of the fuel injection device when the boost voltage Vboost is 65 V and 60 V, and a drive pulse with a predetermined pulse width Ti (constant) 4 is a graph showing temporal changes in current Is when Sa is applied to control circuit 300. FIG. A graph (II-Q curve) showing the relationship between the current integral value II=∫Idt and the injection amount Q of the fuel injection device in the period from the rise to the fall of the drive current Is flowing through the solenoid 203 by the drive pulse Sa, and the boost 5 is a graph showing temporal changes in current Is when voltage and current are supplied with a constant integrated current value II even when the value of voltage Vboost is different (65 V, 60 V). 2 is an II-a curve showing the relationship between current integral value II (=∫Idt) and acceleration a when electrical characteristics (for example, boosted voltage Vboost) are set to three different values; 5 is a graph for explaining a method of measuring individual differences based on an II-a curve showing the relationship between current integral value II (=∫Idt) and acceleration a. 7 is a graph for explaining a method of correcting the current integral value II in the internal combustion engine control system of the second embodiment; 1 is a block diagram summarizing a first embodiment; FIG. 1 is a block diagram summarizing a first embodiment; FIG. FIG. 4 is a block diagram summarizing a second embodiment; 1 is a conceptual diagram when controlling an internal combustion engine 100 having a plurality of cylinders; FIG.

Hereinafter, this embodiment will be described with reference to the accompanying drawings. In the accompanying drawings, functionally identical elements may be labeled with the same numbers.

[First embodiment]
First, referring to FIG. 1, an internal combustion engine control system according to a first embodiment will be described. FIG. 1 shows an internal combustion engine control device according to a first embodiment and an internal combustion engine having a fuel injection device to be controlled.

The internal combustion engine 100 has a fuel injection device (injector) 116 for controlling fuel injection, and an ECU 200 and a control circuit 300 are provided as devices for controlling the internal combustion engine 100 including the fuel injection device 116. there is The ECU 200 is a control device that controls the entire internal combustion engine 100, and the control circuit 300 is a circuit that controls the fuel injection device 116, which will be described later. The ECU 200 internally includes a memory 201 and a CPU 202 , and stores a computer program for controlling the internal combustion engine 100 in the memory 201 .

The ECU 200 includes a standard characteristic data storage section 21 , a setting section 22 , a measurement section 23 and a correction section 24 . Standard characteristic data storage unit 21 may be configured by memory 201 of ECU 200 . The setting unit 22 , the measurement unit 23 , and the correction unit 24 can be configured by the CPU 202 of the ECU 200 , a computer program for control, and/or hardware outside the CPU 202 .

Standard characteristic data storage unit 21 stores standard characteristic data (first characteristic data) representing standard characteristics of fuel injection device 116 in internal combustion engine 100 that is controlled by ECU 200 . When there are a plurality of fuel injection devices 116 with the same specifications, the standard characteristic data can be stored in the standard characteristic data storage unit 21 as data according to the characteristics of any one of the plurality of devices. The standard characteristic data includes, for example, the pulse width Ti (first physical quantity) of the drive pulse Sa for driving the fuel injection device 116, and the acceleration a of the valve body when the valve closes when the pulse width Ti is given. It can be data indicating a standard relationship with (second physical quantity). The standard characteristic data is preferably a characteristic near the center of the characteristic distribution of the plurality of fuel injection devices, but is not limited to this.

The setting unit 22 sets the pulse width Ti of the drive pulse Sa for driving the fuel injection device 116 .

In addition, the measurement unit 23 measures the operation of the fuel injection device 116 when it is driven under predetermined conditions, and obtains a predetermined physical quantity.

The correction unit 24 corrects the pulse width Ti of the driving pulse Sa according to the physical quantity obtained by the measurement unit 23 and standard characteristic data stored in the standard characteristic data storage unit 21 . Note that the internal combustion engine 100 is merely an example, and the controlled object is not limited to the illustrated one. The internal combustion engine 100 can be, for example, an internal combustion engine having a plurality of, for example, four cylinders (#1 to #4). FIG. 1 shows only one cylinder out of a plurality of cylinders.

The internal combustion engine 100 includes, for example, an air cleaner 101, an air flow sensor 102, a throttle 103, a collector 104, an intake port 105, a cylinder 106, a fuel tank 111, a low pressure pump 112, a low pressure pipe 113, a high pressure pump 114, a high pressure pipe 115, a fuel injection It has a device (injector) 116, a spark plug 121, a piston 122, a connecting rod 123, a crankshaft 124, and the like. The internal combustion engine 100 takes in air and fuel in the cylinder 106, ignites the air-fuel mixture with the ignition plug 121, and causes the piston 122 to reciprocate. This reciprocating motion is converted into rotational motion of a crankshaft 124 by a link mechanism including a connecting rod 123 and the like, and serves as a driving force for moving an automobile or the like.

After the air is filtered by an air cleaner 101, the flow rate of the air taken into the internal combustion engine 100 is measured by an air flow sensor 102, and the flow rate is adjusted by a throttle 103. influx.

On the other hand, the fuel in the fuel tank 111 is sent to the low pressure pipe 113 by driving the low pressure pump 112 . The fuel in the low-pressure pipe 113 is sent to the high-pressure pipe 115 by driving the high-pressure pump 114, and the fuel in the high-pressure pipe 115 is maintained at a high pressure. A fuel injection device 116 is attached to the outlet of the high-pressure pipe 115 to control injection of high-pressure fuel. As will be described later with reference to FIG. 2, a solenoid (described with reference to FIG. 2) is provided in the fuel injection device 116, and the valve body of the fuel injection device 116 is opened by applying an electric current to the solenoid. , fuel is injected.

Next, an example of the structure of fuel injection device 116 will be described with reference to the cross-sectional view of FIG. Fuel injector 116 may be configured with housing 201 , core 202 , solenoid 203 , valve body 204 , anchor 205 , valve seat 206 , set spring 207 and spring adjuster 208 as an example.

A housing 201 constitutes a casing of the fuel injection device 116 , and a core 202 is fixed inside the housing 201 . A solenoid 203 is arranged around the core 202 . The valve element 204 is arranged with the central axis of the housing 201 as its longitudinal direction, and is arranged movably along the central axis of the housing 201 . Anchor 205 is also connected to the lower end of core 202 via zero spring 210 . A through hole is formed in the central axis of the anchor 205, and the valve body 204 is arranged along this through hole so as to be movable. The movement of the anchor 205 toward the valve seat 206 is restricted by a stopper 211 provided inside the housing 201 .

On the other hand, a set spring 207 is arranged at the upper end of the valve body 204 to push the valve body 204 toward the valve seat 206 . A spring adjuster 208 is fixedly arranged along the inside of the core 202 above the set spring 207 . The spring adjuster 208 can adjust its vertical position within the core 202 , thereby adjusting the elastic force of the set spring 207 . During operation of the internal combustion engine 100 , the interior of the housing 201 is filled with fuel, and when current flows through the solenoid 203 , the anchor 205 is attracted by the solenoid 203 and the lower end of the valve body 204 separates from the valve seat 206 . As a result, the fuel is injected from the nozzle hole 209 of the valve seat 206 blocked by the valve body 204 . When the solenoid 203 is de-energized, the anchor 205 descends against the elastic force of the zero spring 210 and returns to its initial position after the fuel injection is terminated.

Next, a specific example of the configuration of the control circuit 300 that controls the fuel injection device 116 will be described with reference to the circuit diagram of FIG.
The fuel injection device 300 includes transistors 301 to 303 as switching elements, a shunt resistor 304, diodes 305 to 308, a capacitor 309, a booster circuit 310, a power supply 311, and a switch control circuit 312, for example.

Transistor 301 is connected to form a current path in series with diode 307 between nodes N1 and N2. A boosted voltage Vboost obtained by further boosting the battery voltage Vbat supplied from the power supply 311 is supplied to the node N1. Diode 307 is connected with the forward direction from node N1 to node N2. The diode 305 is connected between the node N2 and the ground terminal with the forward direction from the ground terminal side toward the node N2.

On the other hand, transistor 302 is connected to form a current path in series with diode 306 between node N3 and node N2. Diode 306 is connected with the forward direction from node N3 to node N2. The booster circuit 310 is connected to output a boosted voltage Vboost to the node N1 with the voltage of the node N3 as an input voltage. A capacitor 309 is connected between the node N1 and the ground terminal and charged with the boosted voltage Vboost. A diode 308 is connected between the node N1 and the node N4 with the forward direction from the node N4 to the node N1. The solenoid 203 described above is connected between the nodes N2 and N4 via terminals 350 and 351 .
A transistor 303 and a shunt resistor 304 are connected in series between the node N4 and the ground terminal.

The switch control circuit 312 is connected to the bases of the transistors 301-303 and controls the conduction of the transistors 301-303. The switch control circuit 312 is supplied with the drive pulse Sa from the ECU 200 described above, and is also supplied with reference data from the setting unit memories 321 to 323 . The set value memory 321 stores the time Tp for applying the boosted voltage Vboost. The set value memory 322 stores the gap time T2 from when the application of the boosted voltage Vboost is stopped until when the battery voltage Vbat is applied. A set value memory 323 stores a holding current Ih that is caused to flow by switching the battery voltage Vbat. The data that can be supplied from the set value memory is an example and is not limited to the above.
Although not shown, a Zener diode can be connected between the terminal 351 and the anode of the diode 308 . By increasing the voltage of the circulating current, the circulating current is made more likely to occur in the capacitor 309 .

As an example, the booster circuit 310 boosts the battery voltage Vbat, which is normally 12-14V, to the boosted voltage Vboost, and the boosted voltage Vboost can be about 40-65V, for example. The boost voltage Vboost is set to a voltage higher than the battery voltage Vbat in order to allow the valve body 204 to rapidly open against the elastic force of the set spring 207 . On the other hand, the battery voltage Vbat may be lower than the boosted voltage Vboost as long as the valve body 204 can be kept open.

Next, the procedure for controlling fuel injection device 116 using control device 300 will be described with reference to the timing chart of FIG. Note that FIG. 4 shows a control procedure when the valve body 204 is fully lifted (when the valve body 204 collides with the core 202).

When the driving pulse Sa having the pulse width Ti is sent from the ECU 200 to the control device 300, the switch control circuit 312 switches the transistors 301 and 303 to the conducting state (ON) in synchronization with the rise of the driving pulse Sa at time t1 ( time t1). Then, the boosted voltage Vboost boosted by the booster circuit 310 is applied between the terminals 350 and 351 of the solenoid 203, and the current Is between the terminals 350 and 351 of the solenoid 203 gradually increases.

As the current Is gradually increases, the magnetic field generated by the solenoid 203 also increases accordingly. When the magnetic attraction that attracts the anchor 205 to the core 202 due to the magnetic field becomes greater than the elastic force of the zero spring 210, the anchor 205 begins to move toward the core 202 (time t2 ). 2, the solid line indicates the displacement of the anchor 205, and the dashed line indicates the displacement of the valve body 204. As shown in FIG.
At the initial position before starting operation, the anchor 205 is pressed against the stopper 211 by the elastic force of the zero spring 210, and the anchor 205 and the stopper 211 are in contact with each other.
On the other hand, there is a gap between the upper surface of the anchor 205 at the initial position and the protrusion 204t of the valve body 204. As shown in FIG. When the anchor 205 rises to fill this gap, the valve body 204 begins to be lifted by the anchor 205 . As a result, fuel begins to flow out from the injection hole 209 (time t3). The operation from the initial position to the start of movement to the contact between the protrusion 204t and the anchor 205 is called a preliminary stroke.

When the time Tp stored in the set value memory 321 has passed since the current Is started to flow through the solenoid 203 at time t1, the switch control circuit 312 in the control circuit 300 switches the transistors 301 and 303 to a non-conducting state (OFF). ) (time t4). The time Tp is usually set to a length sufficient to turn off the transistors 301 and 303 before the anchor 205 collides with the core 202 . This is because it is preferable not to increase the momentum when the anchor 205 collides with the core 202 more than necessary.

When the transistors 301 and 303 are turned off (OFF) at time t4, the current Is that has flowed through the transistor 303 and the shunt resistor 304 to the ground terminal flows through the diode 308 into the capacitor 309 . Due to the back electromotive force generated in the coil of the solenoid 203, the voltage Vs across the terminals of the solenoid 203 (time t4 to t5) is opposite to that before time t4, and the voltage at the terminal 351 becomes higher than the voltage at the terminal 350. That is, the voltage Vs applied to the solenoid 203 takes a negative value.

On the other hand, after the transistors 301 and 303 are switched to OFF at time t4, after the time T2 stored in the set value memory 322 has elapsed, the switch control circuit 312 switches the transistors 302 and 303 to the conductive state (ON). . This causes current from power supply 311 to flow through transistor 302, diode 306, solenoid 203, transistor 303, and shunt resistor 304, and the battery voltage Vbat to be applied across terminals 350 and 351 of solenoid 203 ( time t5). The battery voltage Vbat is lower than the aforementioned boosted voltage Vboost, but is a voltage that allows the valve body 204 and the anchor 205 to maintain contact with the core 202 .

Also, at this time, the voltage generated across the shunt resistor 304 is measured by a voltmeter (not shown), thereby measuring the value of the current Is flowing through the solenoid 203 . The switch control circuit 312 controls the duty ratio for turning on and off the transistor 302 so that the current Is becomes the current value Ih stored in the set value memory 323 .

After that, the drive pulse Sa falls at time t6 after a lapse of time Ti from time t1. The transistors 302 and 303 are also switched to a non-conducting state (OFF) in synchronization with the fall of the drive pulse Sa. Then, the current Is flowing through the solenoid 203 is rapidly attenuated, the magnetic attraction force of the core 202 is attenuated, and the valve body 204 and the anchor 205 are pushed by the elastic force of the set spring 207 to move (down) toward the valve seat 206. to start.

At this time, the current Is flows from the solenoid 203 through the transistor 303 and the resistor 304 to the ground terminal before time t6, but flows through the diode 308 to the capacitor 309 after time t6. Therefore, a back electromotive force is applied to the solenoid 203, and after time t6, the voltage Vs becomes a negative value again. When the current Is converges to 0, the voltage Vs also gradually approaches 0. Eventually, the valve body 204 reaches the valve seat 206, and the ejection of fuel from the injection hole 209 also stops (time t7).

Since the valve body 204 and the valve seat 206 have a predetermined elasticity, the valve body 204 continues to move toward the valve seat 206 due to elastic deformation even after the valve body 204 reaches the valve seat 206 . However, when the valve body 204 moves toward the valve seat 206 to some extent, the elastic deformation of the valve body 204 and the valve seat 206 starts to return to its original state. At this time, the anchor 205 leaves the valve body 204 and continues to move toward the valve seat 206 by inertia (time t8).

The elastic force of the set spring 207 and the force of the fuel pressure are applied to the anchor 205 through the valve body 204 until time t8. disappears. Therefore, the acceleration of the anchor 205 is rapidly reduced. When the acceleration of the anchor 205 changes, the movement of the anchor 205 changes the back electromotive force generated in the solenoid 203, and an inflection point occurs in the voltage Vs of the solenoid 203 (time t8).

Even after the anchor 205 is separated from the valve body 204 , it continues to move toward the valve seat 206 due to inertia, but eventually collides with the stopper 211 . Due to this collision, the acceleration of the anchor 205 changes abruptly, so the back electromotive force generated in the solenoid 203 changes, and an inflection point occurs in the voltage Vs of the solenoid 203 (time t9). The procedure for controlling the fuel injection device 116 by the control circuit 300 has been described above.

FIG. 4 shows a control method when the valve body 204 is fully lifted (operation mode in which the valve body 204 collides with the core 202) as described above. When micro-injecting the internal combustion engine 100, the fuel injection device 116 causes the valve body 204 to be half-lifted (an operation mode in which the valve body 204 is driven to the extent that the valve body 204 does not collide with other components such as the core 202). to control. This half-lift control method will be described with reference to FIG.

When a drive pulse Sa having a pulse width Ti is sent from the ECU 200 to the control circuit 300 at time t1, in synchronization with this rise, the switch control circuit 312 turns on the transistors 301 and 303 (time t1). . Then, the voltage Vboost boosted by the booster circuit 310 is applied between the terminals 350 and 351 of the solenoid 203, and the current Is gradually starts to flow.

As the current Is gradually increases, the magnetic field generated by the solenoid 203 also increases accordingly. When the magnetic attraction force that attracts anchor 205 to core 202 due to the magnetic field becomes greater than the elastic force of zero spring 210 (time t2), anchor 205 moves in the direction of core 202 as shown in the graph of "displacement H" in FIG. start moving. At the initial position before starting operation, the anchor 205 is pressed against the stopper 211 by the elastic force of the zero spring 210, and the anchor 205 and the stopper 211 are in contact with each other.

As in the case of full lift, there is a gap between the upper surface of the anchor 205 at the initial position and the projection 204t of the valve body 204. When the preliminary stroke raises the anchor 205 to fill this gap, the valve body 204 begins to be lifted by the anchor 205 . As a result, fuel begins to flow out from the injection hole 209 (time t3).

The operation from time t1 to t3 is substantially the same as in the case of full lift (FIG. 4), but in the case of half lift, the pulse width Ti of drive pulse Sa is shorter than Tp stored in set value memory 321. , the drive pulse Sa falls at time t10 before time t1+Tp, and the transistors 303 and 301 are switched to a non-conducting state (OFF). Then, before the valve body 204 is fully lifted, in other words, before the valve body 204 and the core 202 collide, the valve body 204 reaches the valve seat 206 at time t11. After that, the valve body 204 stops at this position and only the anchor 205 continues to move. The locus of displacement of the valve body 204 at this time draws a parabola as shown in FIG. Further, as in the case of full lift, an inflection point occurs in the voltage Vs at time t11 when the valve body 204 reaches the valve seat 206 .

In the conventional technology, the valve closing time length Tb (the time from the time when the drive pulse Sa rises to the time when the valve body 204 reaches the valve seat 206. In FIG. 4, Tb=t7−t1, and in FIG. 5, Tb = t11 - t1), and by correcting the pulse width Ti of the driving pulse Sa according to the valve closing time length Tb, the individual difference of the fuel injection device 116 is corrected. The problem to be solved when applying this technique is how to determine the drive pulse Ti from the detected valve closing time length Tb.

For example, if the target value Tbt of the valve closing time length Tb is constant, by performing PID feedback control as shown in FIG. Ti can be controlled. However, since the load of the internal combustion engine always fluctuates, the target value Tbt always fluctuates. Therefore, it is difficult to achieve desirable control of the driving pulse width Ti with PID feedback control.

Therefore, in the first embodiment, the individual difference of the fuel injection device 116 is estimated based on the valve closing time length Tb, and the pulse width Ti of the driving pulse Sa is corrected based on the individual difference.

In order to explain the significance of this first embodiment, first consider the current Is of the solenoid 203 and the displacement of the valve body 204 when the pulse width Ti is changed to a plurality of values. For example, as shown in FIG. 7(a), the pulse width Ti of the driving pulse Sa is set to Ti1, Ti2, and Ti3 (Ti1<Ti2<Ti3), and the valve body 204 is set to a so-called half-lift in each case. When the valve body 204 is displaced (to the extent that the valve body 204 does not collide with the core 202), the larger the pulse width Ti of the current Is, the larger the maximum value of the current Is and the longer the period during which the current Is is flowing.

On the other hand, the motion of the valve body 204 is parabolic motion, as shown in FIG. 7(b). The height (maximum value of the lift amount of the valve body 204) and the width (time from valve opening to valve closing of the valve body 204) of the parabola of the parabolic motion differ depending on the size of the pulse width Ti, and the pulse width Ti is large. , the height and width of the parabola are also increased. As can be seen from the respective parabolic motion graphs (FIG. 7), the initial velocity vo when the valve body 204 opens is substantially constant (vo1≈vo2≈vo3) regardless of the pulse width Ti. However, the acceleration a of the parabolic motion of the valve body 204 differs depending on the pulse width Ti (a1<a2<a3), and the value of the acceleration a tends to decrease as the pulse width Ti increases. The relationship between the acceleration a when the valve is closed and the pulse width Ti is shown in the graph of FIG. It should be noted that the acceleration a at the time of valve closing assumes the acceleration of the valve body 204 in the valve closing direction (downward direction) to be positive.

However, the Ti-a curve in FIG. 8 changes depending on the individual fuel injection device 116 . That is, if the Ti-a curve for a standard fuel injector 116 looks like curve CtiaS in FIG. The curve will differ from this standard Ti-a curve CtiaS depending on the individual.

Although there are various factors that cause individual differences in the fuel injection device 116, it is considered that the elastic force Fsp of the set spring 207 is dominant. The Ti-a curves of three fuel injection devices (including a standard fuel injection device) with different elastic forces Fsp of the set spring 207 are curves Ctia1, Ctia2, and CtiaS as shown in FIG. These three Ti-a curves CtiaS, Ctia1, and Ctia2 have substantially the same curve shape, and are in a relationship of being translated in the direction of the axis (vertical axis) of the acceleration a. In other words, the difference in the elastic force Fsp of the set spring 207 as an individual difference only translates the Ti-a curve, and the shape of the Ti-a curve can be considered unchanged. The reason is that when the elastic force Fsp of the set spring 207 increases or decreases, a value obtained by dividing the increase/decrease ΔFsp of the elastic force Fsp by the sum of the mass of the valve body 204 and the anchor 205 appears as the increase/decrease of the acceleration a. be.

This first embodiment focuses on the fact that the shape of the Ti-a curve is constant regardless of individual differences, and that it moves in parallel in the vertical axis direction due to individual differences. A curve is identified and based on which the pulse width Ti is corrected. In this method, a standard Ti-a curve (first characteristic data) is translated in accordance with the detected individual difference to specify a Ti-a curve (second characteristic data) specific to the fuel injection device. Then, the pulse width Ti is corrected based on the obtained unique Ti-a curve.

Various methods are conceivable as a method of identifying the individual difference, but here, the pulse width Ti of the driving pulse Sa is set to a predetermined value and the acceleration a of the valve body 204 when the valve body 204 is half-lifted. is obtained as an individual difference.
In order to obtain the acceleration a of the valve body 204, the valve body 204 and the anchor 205 are given a pulse width Ti such that the valve body 204 and the anchor 205 are so-called half-lifted, and the valve body 204 and the anchor 205 are caused to make a parabolic motion. Assuming that the timing (time) at which the valve body 204 opens is ta', the timing (time) at which the valve is closed is tb, and the initial velocity of the valve body 204 is vo, the acceleration a is expressed by the following equation.

During the movement (preliminary stroke) of the anchor 205 until the anchor 205 contacts the protrusion 204t of the valve body 204, the anchor 205 is not affected by the elastic force Fsp of the set spring 207 and the fuel pressure. Therefore, the timing ta' is substantially constant without being affected by individual differences, fuel pressure, and pulse width Ti. Therefore, the timing ta' is acquired in advance as a constant. For example, it is measured in advance or obtained by computer simulation based on design values. The acquired value ta' is stored in the ECU 200 or the control circuit 300. FIG.

Also, since the initial velocity vo is also determined by the movement of the anchor 205 during the preliminary stroke, it is not affected by the elastic force Fsp of the set spring 207 or the fuel pressure. Therefore, the initial velocity vo can also be obtained as a constant in advance by measurement or computer simulation, and stored in the ECU 200 or the control circuit 300 .
Therefore, the acceleration a is obtained by obtaining the valve closing timing tb based on a predetermined method and substituting the obtained valve closing timing tb into [Expression 1].

As shown in FIG. 10, the valve closing timing tb is detected by the timing of the inflection point of the voltage Vs generated by the impact when the anchor 205 collides with the stopper 211 when the valve is closed. The inflection point of the voltage Vs may be specified by measuring the voltage Vs between the terminals of the solenoid of the fuel injection device itself, or by measuring another voltage such as the voltage across the shunt resistor 304. can. Once the timing tb is obtained in this way, the acceleration a can be calculated according to [Equation 1].

When the acceleration a is calculated, the target fuel injection device is adjusted based on the deviation Δa from the standard value of the acceleration a and the standard characteristic data (Ti-a curve CtiaS) stored in the standard characteristic data storage unit 21. A Ti-a curve specific to is identified. Here, the deviation Δa is an individual difference in acceleration, and the correction unit 24 detects the individual difference. This specific procedure will be described with reference to FIGS. 11 and 12. FIG. The standard characteristic data stored in the standard characteristic data storage unit 21, that is, the Ti-a curve CtiaS (function a=f(Ti)) can be expressed as shown in FIG. 11, for example. If the target fuel injection device has characteristics according to the standard Ti-a curve CtiaS, and a drive pulse Sa with a pulse width Ti=Ti* is applied, the acceleration a is the standard Ti-a A value ao (=f(Ti*)) on the curve CtiaS is obtained.

However, since the characteristics of the target fuel injection device are different from the standard Ti-a curve, even if the drive pulse Sa with the pulse width Ti=Ti* is applied, the acceleration a at the time of valve closing will not be ao. different values. In the present embodiment, the deviation Δa (=a−ao) between the value of the measured acceleration a and the standard ao is calculated to identify the Ti-a curve unique to the target fuel injection device. The Ti-a curve for the subject fuel injector is identified as the standard Ti-a curve CtiaS translated vertically by Δa.

As shown in FIG. 21, when the internal combustion engine 100 is a four-cylinder engine, a driving pulse Sa having a pulse width Ti* is applied to each of the four fuel injection devices 116 among the four cylinders. Accelerations a1*, a2*, a3*, and a4* of the valve bodies 204 of the four fuel injection devices 116 are detected.
The individual difference Δaj (j=1 to 4) is obtained by the following [Equation 2] as shown in FIG.

Once the Ti-a curve specific to the fuel injector 116 of interest is identified, the pulse width Ti is subsequently corrected according to this Ti-a curve. An example of this specific method will be described with reference to FIG.

First, as shown in FIG. 13(a), from the Ti-Q curve showing the relationship between the pulse width Ti of the drive pulse Sa given to the fuel injection device according to the standard characteristics and the target injection amount Q, the target injection amount Obtain the drive pulse width Ti_tar required to inject Qtar.

As shown in FIG. 13(b), the standard Ti-a curve CtiaS is translated by Δa in the direction of the vertical axis to obtain the Ti-a curve CtiaT of the target fuel injection device. Incidentally, when the standard Ti-a curve CtiaS is represented by the function a=f(Ti), this Ti-a curve CtiaT can be represented by the function a=f(Ti)+Δa.

Then, as shown in FIG. 13(c), the correction value Ti_comp of the drive pulse Sa is calculated based on the standard Ti-a curve CtiaS and the Ti-a curve CtiaT of the target fuel injection device. The procedure is described below.
(1) Acceleration a_tar (=f(Ti_tar)) when a drive pulse Sa with a pulse width Ti=Ti_tar is applied to a standard fuel injection device is calculated based on a standard Ti-a curve CtiaS.
(2) Find the pulse width Ti_comp for realizing the acceleration a_tar in the target fuel injection device based on the Ti-a curve CtiaT determined for the target fuel injection device. The pulse width Ti_comp can be obtained by solving [Equation 3] below.

Alternatively, the slope K=da/dTi at the point (Ti, a)=(Ti_tar, a_tar) of the standard Ti-a curve CtiaS can be used to approximate the pulse width Ti_comp according to [Equation 4] below. You can ask for

As described above, according to the internal combustion engine control apparatus of the first embodiment, the ECU 200 generates the drive pulse Sa having the pulse width Ti_comp obtained in this way and supplies it to the control circuit 300, whereby the fuel By correcting the individual difference of the injection device, highly accurate injection amount control can be realized.

In particular, the measurement unit 23 detects the characteristics of the target fuel injection device in a certain limited operating state (specific drive pulse width Ti), and based on this, the individual difference of the target fuel injection device in the entire operating range is determined. can be corrected. This is because, although the Ti-a curve differs depending on the individual fuel injection valve, the elastic force Fsp of the set spring 207 is dominant as the cause of the difference. This is because it can be represented by parallel displacement. This allows specifying a fixed difference at one operating point to infer the Ti-a curve at another operating point. As a result, the variation in the injection amount of the fuel injection device is reduced, and it is possible to reduce the exhaust gas amount and improve the fuel efficiency.

[Second embodiment]
Next, an internal combustion engine control system according to a second embodiment of the invention will be described. As described above, the internal combustion engine control system of the first embodiment assumes variations in mechanical characteristics such as the elastic force Fsp of the set spring 207 as individual differences in fuel injection devices, and It corrects for the difference. On the other hand, the internal combustion engine control system of the second embodiment makes it possible to simultaneously correct individual differences in electrical characteristics in addition to such mechanical characteristics. Individual differences in electrical characteristics include variations in the inductance of the solenoid 203, variations in the resistance of wiring and the like, variations in the boosted voltage Vboost, variations in the capacitance of the capacitor 309, and the like.

FIG. 14 shows an internal combustion engine control system according to a second embodiment and an internal combustion engine having a fuel injection device to be controlled. The same reference numerals are given to the same components as in FIG. 1, and detailed description thereof will be omitted below.

The standard characteristic data storage unit 21 of the second embodiment stores the relationship between the current integral value II and the acceleration a instead of the standard Ti-a curve data of the first embodiment. Since the variation in the electrical characteristics is reflected in the current integral value II, the variation in the electrical characteristics can be dealt with by using the current integral value II instead of the driving pulse length Ti. In addition to or instead of setting the pulse width of the drive pulse Sa, the setting unit 22 sets the current integral value of the current Is flowing through the solenoid 203 . The measurement unit 23 measures the acceleration a of the valve body 204 when a current of a predetermined integrated current value is applied to the solenoid 203 . Further, the correction unit 24 corrects the current integral value. Further, in the second embodiment, the ECU 200 is provided with a pulse adjusting section 25 that adjusts the pulse width Ti of the drive pulse Sa. The pulse adjustment unit 25 includes an integrator 25A that integrates the current Is, and a comparator 25B that compares the current integration value of the integrator 25A with a target integration value.

The upper graph in FIG. 15A is a graph (Ti-Q curve) showing the relationship between the pulse width Ti and the injection amount Q of the fuel injection device when the boost voltage Vboost is 65V and 60V. The lower graph in FIG. 15A is a graph showing temporal changes in the current Is when a driving pulse Sa with a predetermined pulse width Ti (constant) is applied to the control circuit 300. In FIG. It can be seen that the shape of the Ti-Q curve changes depending on the difference in the value of the boosted voltage Vboost (65 V, 60 V), and the maximum value of the current Is also changes.

On the other hand, the upper graph in FIG. 15B shows the relationship between the current integral value II=∫Idt and the injection amount Q of the fuel injection device in the period from the rise to the fall of the drive current Is flowing through the solenoid 203 due to the drive pulse Sa. It is a graph (II-Q curve). From this graph, it can be seen that the relationship between the current integral value II and the injection quantity Q is not affected by the boosted voltage. This integrated current value II is represented by the area of the hatched portion for each voltage in the lower graph of FIG. 15B. The lower graph in FIG. 15B is a graph showing the current Is when the voltage is applied so that the current integral value II is constant even when the boosted voltage Vboost has different values (65V, 60V).

15A and 15B illustrate the effects of variations in the boosted voltage Vboost, the same situation can occur even if there are variations in wiring resistance, inductance of the solenoid 203, etc. among the fuel injection devices. In other words, the inventors' experiments have shown that the Ti-Q curve fluctuates but the II-Q curve does not change when there is variation in resistance, inductance, capacitance, or the like. Therefore, by obtaining the integrated value II of the current Is and performing control according to the II-Q curve, not only the variation in the mechanical characteristics but also the variation in the electrical characteristics can be corrected according to the second embodiment. is the purpose of the controller of

FIG. 16A is an II-a curve showing the relationship between the current integral value II (=∫Idt) and the acceleration a in three fuel injection devices with different elastic forces of the set spring 207. FIG. As shown in FIG. 16A, when the elastic force of the set spring 207 is different, the II-a curve changes (CiaS, Ciia1, Ciia2), but the shape of the curve does not change. ) is translated only. This is the same property as the Ti-a curve described in FIG. 9 of the first embodiment. The reason is that, as in the case of the first embodiment (Ti-a curve), when the elastic force Fsp of the set spring 207 increases or decreases, the increase or decrease ΔFsp of the elastic force Fsp is the mass of the valve body 204. This is because the value obtained by dividing by the sum of the masses of the anchors 205 appears as an increase in the acceleration a.

In the first embodiment, variations in electrical characteristics were not taken into consideration, so as shown in FIG. was made. However, in the second embodiment, even if the same fuel injection device is driven with the same pulse width Ti, the current integral value II varies from II1* in FIG. 16B to II1* in FIG. II2* and II3* (in particular, the boosted voltage Vboost varies from shot to shot due to the timing of boosting and injection. This is the main cause of variations in the integrated current value II). Advantageously, however, the distances Δa1*, Δa2*, Δa3* between the accelerations a1*, a2*, a3* obtained in each measurement and the standard II-a characteristic are constant. Because, as in the first embodiment, Δa1*, Δa2*, and Δa3* are equal to the value obtained by dividing the elastic force Fsp of the set spring 207 by the sum of the masses of the valve body 204 and the anchor 205. This is because it is a value that is not affected by the integrated value of the applied current.

Therefore, the II-a curve CiiaS of the standard fuel injection device is stored in the standard characteristic data storage unit 21, and the acceleration a and the current are calculated for each individual fuel injection device when driven with a predetermined drive pulse width Ti*. The integral value II is measured, and the individual difference Δa between the target fuel injection device and the standard characteristics is obtained based on the distance between the combination of the current integral value II and the acceleration a and the standard II-a curve CiiaS. . If the standard II-a curve is expressed by the function a=g(II), then Δa=a−g(II). A specific II-a curve is identified based on the standard II-a curve CiiaS and the individual difference Δa, and the current integral value II is corrected based on this curve. That is, by translating the standard II-a curve along the vertical axis according to the obtained deviation Δa of the acceleration a, the II-a curve of the target fuel injection device is obtained, and according to this II-a curve The current integral value II can be corrected. According to this correction method, it is possible to simultaneously correct variations in electrical characteristics and variations in mechanical characteristics.

A method of correcting the current integral value II in the internal combustion engine control system of the second embodiment will be described in detail below. Correction of the current integral value II is performed according to the following procedure.
(1) First, as shown in FIG. 17(a), the integrated current value II_tar required to inject the target injection amount Qtar is obtained from the II-Q curve of the fuel injection device according to the standard characteristics.
(2) As shown in FIG. 17(b), the standard II-a curve CiiaS is translated by Δa in the direction of the vertical axis to obtain the II-a curve CiiaT of the target fuel injection device. If the standard II-a curve CiiaS is represented by the function a=g(II), this II-a curve CiiaT can be represented by the function a=g(II)+Δa.

Then, by the method shown in FIG. 17(c), the correction value II_comp of the current integral value II is calculated based on the standard II-a curve CiiaS and the II-a curve CiiaT of the target fuel injection device. The procedure is as follows.
(1) Calculate the acceleration a_tar (=g(II_tar)) when the current integral value II=II_tar is given to the standard fuel injection device.
(2) A current integral value II_comp for realizing the acceleration a_tar in the target fuel injection device is determined based on the unique II-a curve CiiaT determined for the target fuel injection device.
The current integral value II_comp can be obtained by solving [Equation 5] below. When the current integral value II_comp is thus obtained, the target fuel injection device is controlled using this current integral value II_comp. Specifically, the integrator 25A in the pulse adjustment unit 25 measures the integrated value of the current Is, and the comparator 25B compares the measured integrated value with the target value II_comp of the current integrated value. The drive pulse Sa is discontinued at the timing at which both are matched.

Alternatively, the slope K = da/dII at the point (II, a) = (II_tar, a_tar) of the standard II-a curve CiiaS is used to approximate the current integral II_comp according to [Equation 6] below. Even if it is calculated theoretically, a value almost equal to that obtained by solving with [Equation 5] is obtained.

As described above, according to the internal combustion engine control apparatus of the second embodiment, the pulse adjustment section 25 of the ECU 200 generates the drive pulse Sa that gives the current integral value II_comp obtained in this way, and the control circuit 300 supply to As a result, it is possible to correct the individual difference of the fuel injection device, including not only the variation in the mechanical characteristics but also the variation in the electrical characteristics, thereby achieving highly accurate injection amount control.

(wrap up)
18 and 19 summarize the operation of the control device of the first embodiment.
FIG. 18 shows the normal operation mode of the first embodiment, and FIG. 19 shows the target injection amount Q and the drive A correction mode for correcting the pulse width of the pulse Sa is shown.

As shown in FIG. 18, in the normal operation mode, the target injection amount Q is determined by the ECU 200, and the pulse width Ti of the drive pulse Sa for obtaining the target injection amount Q is set by the setting unit 22. As shown in FIG. The control circuit 300 causes a current Is corresponding to this drive pulse Sa to flow through the solenoid 203, and the fuel injection device 116 gives an operation to the valve body 204 according to this current Is.

As shown in FIG. 19, in the correction mode for correcting the pulse width Ti based on the measurement results of the individual characteristics, the measurement unit 23 determines the individual characteristics (acceleration a and deviation Δa) with a predetermined pulse width Ti. is measured and input to the correction unit 24 . The correction unit 24 corrects the pulse width Ti of the drive pulse width Sa based on the obtained solid characteristics. When the internal combustion engine 100 has a plurality of cylinders and a plurality of fuel injection devices corresponding to them, the same pulse width Ti is given to the plurality of fuel injection devices to measure the individual characteristics of each of the plurality of fuel injection devices. . After that, the pulse width is corrected in each of the plurality of fuel injection devices according to the individual individual characteristics obtained in each of the plurality of fuel injection devices. At this time, it is preferable to correct the pulse width of the drive pulse so that the acceleration of the valve bodies of the plurality of cylinders becomes substantially the same.

FIG. 20 summarizes the operation of the second embodiment.
In the normal operation mode, the target injection amount Q is determined by the ECU 200 and the current integral value II for obtaining the target injection amount Q is set by the setting unit 22 . The control circuit 300 causes a current Is corresponding to this current integral value II to flow through the solenoid 203, and the fuel injection device 116 gives an operation to the valve body 204 according to this current Is.

In the correction mode for correcting the current integral value II based on the measurement results of the individual characteristics, the measurement unit 23 measures the individual characteristics (acceleration a and deviation Δa) while giving a predetermined pulse width Ti. Based on this, an individual difference is obtained and input to the correction unit 24 . The correction unit 24 corrects the current integral target value II based on the obtained individual difference. The pulse adjustment unit 25 adjusts the pulse width Ti of the driving pulse Sa according to the current integration target value II, and when the desired pulse width Ti is obtained, the driving pulse Sa is stopped (stopped).

Although the embodiments of the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and modifications can be made without departing from the scope of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are included in the scope of the invention described in the claims and equivalents thereof.

21 Standard characteristic data storage unit 22 Setting unit 23 Measurement unit 24 Correction unit 25 Pulse adjustment unit 100 Internal combustion engine 101 Air cleaner 102 Air flow sensor 103 Throttle 104 Collector , 105... intake port, 106... cylinder, 111... fuel tank, 112... low pressure pump, 113... low pressure pipe, 114... high pressure pump, 115... high pressure pipe, 116... fuel injection device, 121... spark plug, 122... piston, DESCRIPTION OF SYMBOLS 123... Connecting rod, 124... Crankshaft, 201... Housing, 202... Core, 203... Solenoid, 204... Valve body, 204t... Protrusion, 205... Anchor, 206... Valve seat, 207... Set spring, 208... Spring adjuster 209 injection hole 210 zero spring 211 stopper 300 control circuit 301 to 303 transistor 304 shunt resistor 305 to 308 diode 309 capacitor 310 booster circuit 311 power supply 312... Switch control circuit, 321 to 323... Set value memory, 350, 351... Terminals.

Claims (7)

In an internal combustion engine control device that controls a fuel injection device of an internal combustion engine,
The internal combustion engine control device includes a CPU,
The CPU
a storage unit for storing first characteristic data indicating a standard relationship between a first physical quantity relating to the voltage or current applied to the fuel injection device and acceleration relating to the operation of the fuel injection device;
a measurement unit that measures the operation of the fuel injection device when a predetermined condition is applied and acquires the acceleration;
The first physical quantity and the acceleration of the fuel injection device to be measured by the measurement unit based on the acceleration obtained by the measurement unit and the first characteristic data obtained from the storage unit. a correction unit that acquires second characteristic data indicating the relationship of and corrects the first physical quantity based on the second characteristic data,
The measurement unit operates the fuel injection device so as to drive the valve body to such an extent that the valve body of the fuel injection device does not collide with other elements, and measures the initial velocity at which the valve body opens. , where tb-ta' is the time from when the valve body opens until it closes (tb indicates the timing at which the valve body closes, and ta' indicates the timing at which the valve body opens). ) , and an internal combustion engine control device characterized by measuring the acceleration a as a=2vo/(tb-ta'). The measurement unit measures the acceleration based on the timing of the inflection point of the voltage applied to the fuel injection device when the valve body of the fuel injection device is closed under the given condition. 2. The internal combustion engine control system according to claim 1, wherein: 3. The correcting unit acquires the second characteristic data by translating the first characteristic data along the direction of the coordinate axis of the acceleration based on the acceleration measured by the measuring unit. An internal combustion engine controller as described. The fuel injection device is provided in each of the plurality of cylinders,
2. The internal combustion engine control device according to claim 1, wherein said correction unit corrects said first physical quantity so that said acceleration of each cylinder is substantially the same. 2. The internal combustion engine control device according to claim 1, wherein said first physical quantity is a pulse width of a drive pulse supplied to said fuel injection device. 2. The internal combustion engine control device according to claim 1, wherein said first physical quantity is an integral value of current supplied to said fuel injection device. The CPU
an integrator that calculates an integral value of the current;
7. The method according to claim 6, further comprising a comparison unit that compares the integrated current value as the target value and the integrated value output from the integrator, and lowers the drive pulse supplied to the fuel injection device according to the comparison result. An internal combustion engine controller as described.

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