DE102008043183B4 - Apparatus for controlling an amount of fuel actually to be injected by an injector in a multiple injection mode - Google Patents

Abstract

Apparatus for controlling an injector in a multiple injection mode to inject an amount of fuel into an internal combustion engine in an earlier injection and to control the injector after a target interval duration has elapsed to inject fuel into the internal combustion engine in a later injection, the apparatus comprising a storage unit configured to store therein a reference fuel injection characteristic of the injector with respect to a target interval duration within a usable range determined for the target interval duration, the target interval duration being an interval between stopping fuel injection by the injector in the earlier injection and represents a start of fuel injection by the injector in the later injection, wherein the reference fuel injection characteristic depends on at least a quantity of fuel supplied from the injector in the injector injected later injection; and an actual fuel injection characteristic obtaining unit configured to obtain an actual fuel injection characteristic of the injector with respect to the target interval duration within at least a portion in the usable range; the apparatus being characterized by a characteristic point detecting unit configured to detect at least one characteristic point of the actual fuel injection characteristic of the injector, the at least one characteristic point having a locally specific characteristic in the actual fuel injection characteristic of the injector; a phase difference calculating unit configured to calculate a phase difference between the reference fuel injection characteristic and the obtained actual fuel injection characteristic based on the at least one characteristic point of the actual fuel injection characteristic and at least one characteristic point of the reference fuel injection characteristic corresponding to the at least one characteristic point of the actual fuel injection characteristic; a phase correction unit configured to shift the reference fuel injection characteristic by the calculated phase difference so as to correct the reference fuel injection characteristic so as to ...

Description

BACKGROUND OF THE INVENTION

Field of the invention

The present invention relates to an apparatus for controlling an injector in a multi-injection mode and to a fuel injection system with this apparatus. In the multiple injection mode, the internal combustion engine causes the injector to perform multiple fuel injection surges in one operating cycle of the internal combustion engine.

Description of the Related Art

Fuel injection systems are conventionally used to control fuel injection by an injector for each cylinder of an internal combustion engine. In order to reduce combustion noise, nitrogen oxide (NOx) emissions, and / or exhaust filter regeneration, one type of fuel injection system is designed to cause an injector in a multi-injection (multi-stage) mode to make multiple fuel injections in an operating cycle of the internal combustion engine.

The injector is normally designed to move a valve to open an orifice thereby injecting an amount of fuel into a corresponding cylinder and to move the valve to close the orifice thereby stopping fuel injection therein.

In the multi-injection mode, the one-kind fuel injection system is designed to cause an injector to inject a small amount of fuel injection into the engine before and after a main fuel injection stroke (main fuel injection). The main fuel injection allows the engine to generate a torque. The injection before the main fuel injection will hereinafter be referred to as a "pilot injection", and the injection after the main injection will hereinafter be referred to as a "post-injection".

In the multiple injection mode, water hammering occurs in the injector at the instant the valve closes the opening of the injector to stop the fuel injection surge in each stage injection, resulting in pressure pulsing in the injector. The pressure pulsations affect a valve opening / closing timing of the injector. The magnitude of the pressure pulsations depends on an elapsed time since the stop of the fuel injection stroke in each injection stage.

For this reason, when the pressure pulsations in the injector occur in an earlier injection, the fuel injection amount injected from the injector in a later injection following the earlier injection varies depending on an interval duration. The interval duration is defined as an interval period from the stop of fuel injection in an earlier injection to the start of fuel injection in a later injection following the earlier injection. For the sake of simplicity, the interval duration may be described below as an "interval time between an earlier and a later injection" and the like.

The changes in the amount of fuel injected from an injector can reduce the accuracy in controlling the amount of fuel to be injected from an injector.

Therefore, a method for overcoming the problem of reduced accuracy has been proposed. The method includes, at the time of delivery of a fuel injection system or the like, the following steps:
Measuring a characteristic indicative of the relationship between the interval duration and a pressure pulsation for each injector; and
Determining IQ reference characteristic data in, for example, a map format on the basis of the measured characteristic.

The I-Q reference characteristic data represents a reference relationship between a target interval duration from an earlier injection by an injector to a later injection following the earlier injection and a correction amount of an amount of fuel actually injected from the injector in the later injection.

Specifically, when a target interval time is set between an earlier injection and a later injection performed by an injector in the multi-injection mode, it is possible to refer to the IQ reference characteristic data to obtain a correction value that matches the set one Target interval duration corresponds. Thus, an instruction value corresponding to the target injection amount for the later injection is corrected on the basis of the correction value, and thereafter the corrected instruction value is output to the injector. This allows an amount of fuel actually injected by the injector to match the target fuel amount for later injection.

However, a fuel injection characteristic of injectors varies depending on their individual deviations (manufacturing variations) and aging of each injector. For this Reason, an actual interval duration between adjacent fuel injections and a target interval time between them preset in the IQ reference characteristic data are different from each other.

As a result, even if a target amount of fuel to be injected by an injector in a later injection is corrected on the basis of a target interval time between an earlier injection and the later injection, an amount of fuel supplied from the injector in the later injection actually is injected, deviates from the target fuel quantity. The target amount of fuel to be injected from an injector will also be referred to as a "target injection amount" hereinafter.

The JP 2005-264 810 A discloses a fuel injection pattern adjusting technique used in such a multi-injection mode including the pilot injection and a main injection with an injection period therebetween.

Specifically, the fuel injection pattern adjustment technique is designed to execute a plurality of sets of multiple injections, each set of which includes the pilot injection and the main injection, while changing the interval between the pilot injection and the main injection for each set.

This results in frequency changes of noise, including machine noise. The frequency changes of the sounds including the engine noise should lead to a good feeling of a user with regard to the noise and a reduction of the noise.

However, the fuel injection pattern setting technique can not determine the deviation of an actual interval time between adjacent fuel injections in such a multi-injection mode from a target injection duration between them preset in the IQ reference characteristic data due to deviations of the fuel injection characteristics of injectors depending on their individual deviations (manufacturing variations) and aging of each injector.

The JP 2007-132 334 A discloses an apparatus for controlling an injector in a multi-injection mode according to the preamble of claim 1.

The DE 103 09 720 B4 discloses a method for determining a phase shift from a pressure oscillation in the rail pressure curve for determining a deviation of a drive duration of a fuel injection. Phase shifts of characteristic features occurring during opening and / or closing of an injector, such as pressure gradients in the rail pressure course, are detected and compared with previously stored reference vibration values.

SUMMARY OF THE INVENTION

In view of the prior art, it is an object of at least one aspect of the present invention to provide systems for:
Commanding an injector to perform a first fuel injection shock as a multiple injection and to execute a second fuel injection shock after a target interval duration has elapsed since a stop of the first fuel injection shock; and
Learning a deviation of an actual interval duration, which has elapsed from the stop of the first fuel injection shock to the start of the second fuel injection shock, from the target interval duration with high accuracy over an entire time range usable for the target interval duration.

This object is achieved with a device for controlling an injector in a multi-injection mode according to claim 1 and a fuel injection system according to claim 9. Advantageous developments of the invention are the subject of the dependent claims.

In general, the inventors of this application have paid attention to the fact that:
a graph of an injection rate measured during injection of a target fuel amount by an injector over time before and after stoppage of fuel injection with a change in the target fuel amount as 2 mm ³ / stroke, 10 mm ³ / stroke, 40 mm ³ / Push and 80 mm ³ / push changes (see 1A ). The unit "mm ³ / stroke" represents a quantity of fuel (mm ³ ) that is injected by one injector per stroke of its needle valve. The timing when the injection of the target fuel amount is stopped is set to "0 (ms)" as a reference timing.

The inventors of this application have also focused on the fact that:
a history of a pressure in the injector over time before and after the stop of the fuel injection changes with a change in the target fuel amount as 2 mm ³ / stroke, 10 mm ³ / stroke, 40 mm ³ / stroke, and 80 mm ³ / stroke.

How clear in 1A 1, the waveforms of the injection rates for the respective different target injection quantities in the earlier injection differ relative to an interval duration of the stop of the earlier injection until the start of the later injection from each other before the stop of the fuel injection in the earlier injection.

In contrast, the waveforms of the injection rates for the respective different target injection quantities in the previous injection relative to an interval period after the stop of the fuel injection in the earlier injection are substantially identical to each other.

Moreover, the timings of the pressures in the injector for the respective different target injection amounts relative to an interval duration in the earlier injection are different from each other before stop of the fuel injection in the earlier injection.

In contrast, the histories of the pressures in the injector for the respective different target injection amounts after the stop of the fuel injection in the early injection are substantially identical to each other.

In other words, the characteristics of the pressure pulsations in the injector for the respective different target injection amounts substantially coincide with each other regardless of an elapsed time since the stop of the fuel injection in the earlier injection.

Moreover, when a plurality of sets of first and second fuel injection pulses are executed in the multi-injection mode while a target interval duration between the first injection pulse and the second injection pulse of each set is changed such that:
a target injection quantity for the first injection stroke of each set differs from that for the first burst of another set;
a target injection amount for the second stroke of each set is the same as that for the second stroke of another set; and
a timing of stopping the first injection stroke of each set is the same as that of stopping the first stroke of another set, the inventors found that:
Currents of fuel amounts "Q" actually injected from the injector by the plurality of sets of first and second fuel injection pulses are substantially periodic and identical to the change of the target interval duration (see FIG 1B ).

For example, the course of the actual injection amount "Q" by one of the plurality of sets of first and second fuel injection strokes when the target injection amount for the first shock is set to 50 mm ³ / shock is compared with the change of the target interval duration by the solid line in FIG 1B shown. Similarly, the course of the actual injection amount "Q" by another one of the plurality of sets of first and second fuel injection surges when the target injection amount for the first impact is set to 10 mm ³ / shock is compared with the change of the target interval time by the dotted line in FIG 1B shown. In addition, the course of the actual injection amount "Q" by another one of the plurality of sets of first and second fuel injection surges when the target injection amount for the first impact is set to 2 mm ³ / shock is compared with the change of the target interval duration by the broken line in FIG 1B shown.

Specifically, a change of a fuel injection amount that is actually injected from an injector by a second injection that follows a first injection in the multiple injection mode greatly depends on a change of an actual target interval duration between the first and second injections.

Thus, actual I-Q characteristic data of an injector relative to the target interval duration in phase differs from the I-Q reference characteristic data for the injector relative to the target interval duration.

At least one aspect of the present invention has been developed on the basis of the background described above.

Specifically, according to the at least one aspect of the present invention, an apparatus for controlling an injector in a multi-injection mode to inject an amount of fuel into an internal combustion engine in an earlier injection and for controlling the injector after a target interval period has elapsed is provided by an amount of fuel to inject in a later injection into the internal combustion engine. The apparatus has a storage unit configured to store therein a reference fuel injection characteristic of the injector relative to a target interval duration within a usable range determined for the target interval duration. The target interval duration represents an interval between a stop of fuel injection by the injector in the earlier injection and a start of fuel injection by the injector in the later injection. The reference fuel injection characteristic depends on at least a fuel injection amount injected from the injector in the later injection , The apparatus has a unit for obtaining an actual fuel injection characteristic configured to provide an actual fuel injection characteristic of the injector relative to the target interval duration within at least one of Section in the usable area. The apparatus has a characteristic point detection unit configured to detect at least one characteristic point of the actual fuel injection characteristic of the injector. The at least one characteristic point has a locally specific characteristic in the actual fuel injection characteristic of the injector. The apparatus has a phase difference calculating unit configured to calculate a phase difference between the reference fuel injection characteristic and the obtained actual fuel injection characteristic based on the at least one characteristic point of the actual fuel injection characteristic and at least one characteristic point of the reference fuel injection characteristic corresponding to the at least one characteristic point of the actual fuel injection characteristic corresponds. The apparatus further includes a phase correcting unit configured to shift the reference fuel injection characteristic by the calculated phase difference so as to correct the reference fuel injection characteristic so as to approximate the obtained actual fuel injection characteristic; and a fuel injection correction unit configured to control the injector based on the corrected reference fuel injection characteristic to correct an amount of fuel injected from the injector in the later injection.

In the at least one aspect of the present invention, at least one characteristic point of the actual fuel injection characteristic of the injector is detected by the characteristic point detection unit. The at least one characteristic point has a locally specific characteristic in the actual fuel injection characteristic of the injector, so that it is easily identifiable with respect to the actual fuel injection characteristic as compared to another point thereon.

On the basis of the at least one characteristic point of the actual fuel injection characteristic and the at least one characteristic point of the reference fuel injection characteristic corresponding to the at least one characteristic point of the actual fuel injection characteristic, a phase difference between the reference fuel injection characteristic and the obtained actual fuel injection characteristic is calculated by the phase difference calculating unit.

As described above, the actual fuel injection characteristic data, such as the actual I-Q characteristic data, of the injector relative to the target interval duration in phase differs from the reference injection characteristic data, such as the I-Q reference characteristic data, for the injector relative to the target interval duration. For this reason, on the basis of the calculated phase difference, it is possible to easily learn the deviation of an actual interval time between the earlier injection and the later injection from the target interval time with high accuracy within the usable range determined for the target interval duration.

In the at least one aspect of the present invention, the "unit" may be configured by at least one fixed-wire circuit, at least one programmed circuit, at least one functional component of a computer, or combinations thereof. The units may be individual hardware components or may be individual software components combined with hardware.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present invention will become apparent from the following description of embodiments with reference to the accompanying drawings, in which:

1A Graphs, one of which schematically shows progressions of injection rates for respective different target injection quantities in a previous injection relative to an interval duration from the stop of the earlier injection until the start of a later injection, and the other of which schematically shows courses of pressures in an injector shows the respective different target injection amounts relative to an interval duration in the earlier injection;

1B FIG. 12 is a graph schematically illustrating curves of fuel quantities injected from an injector by a plurality of sets of first and second fuel injection pulses versus a change of a target interval duration; FIG.

2 Fig. 12 is a view schematically illustrating an example of the structure of a fuel injection system according to an embodiment of the present invention;

3 FIG. 2 is a partial cross-sectional view of each injector incorporated in FIG 2 is shown;

4 Fig. 10 is a timing chart schematically showing a relationship between temporally adjacent fuel injections through an injector in a multi-injection mode and pressure pulsations occurring in the injector according to the embodiment;

5 5 is a timing chart schematically illustrating a relationship between an opening / closing timing of a nozzle needle of an injector and corresponding rise / fall timings of a current pulse, and a relationship between an instruction target interval duration, a target interval duration, and an actual interval duration according to the embodiment.

6 FIG. 12 is a flowchart schematically illustrating a learning routine to be executed by an ECU included in FIG 2 is shown, according to the embodiment;

7 FIG. 12 is a schematic view illustrating a graph of actual IQ characteristic data and IQ reference characteristic data according to the embodiment; FIG. and

8th 12 is a view schematically illustrating a deviation of the actual IQ characteristic data from the IQ reference characteristic data in a magnitude offset direction according to the embodiment.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

An embodiment of the present invention will be described below with reference to the accompanying drawings.

Regarding 2 is the overall structure of a fuel injection system installed in a motor vehicle 10 according to an embodiment of the present invention. The fuel injection system has a direct fuel injection engine 60 like a diesel engine 60 , which is installed in the motor vehicle, and works to supply fuel to the diesel engine 60 supply.

The fuel injection system 10 also has a fuel tank 12 , a pump 14 , a high pressure pump 16 with a regulating valve 18 , an accumulator 20 , Injectors 30 , an ECU (electronic control unit) 40 serving as a controller, and the like.

The diesel engine 60 is with a variety of cylinders 62 , For example, four, which are hollow inside and in which combustion takes place.

The diesel engine 60 is with a variety of pistons 64 , For example, four, corresponding to the plurality of cylinders 62 are installed. For the sake of simplicity, one of these cylinders 62 in 2 shown schematically. The cylinders 62 are integrated with each other to form a cylinder block.

The piston 64 is at one end, for example the bottom, of the cylinder 62 closed and open at the other end, for example the head. The piston 64 is in the cylinder 62 between an upper compression dead center (TDC) and a lower compression dead center (BDC) reciprocable. The head of the corresponding piston 64 , the cylinder walls and the head of the cylinder 62 form a combustion chamber of the cylinder 62 , The one in each cylinder 62 installed pistons 64 is over a connecting rod 65 with a crankshaft 66 the diesel engine 60 connected.

The diesel engine 60 is further with an inlet valve 70 and an exhaust valve 74 for every cylinder 62 fitted. The diesel engine 60 is with a pair of camshafts 72 and 76 fitted. Each of the camshafts 72 and 76 is designed to rotate by turning the crankshaft 66 to be turned.

The inlet valve 70 is in the cylinder head of a corresponding cylinder 62 built in and is made by a rotation of the camshaft 72 rotatably driven. In particular, the inlet valve 70 driven to open, thereby allowing air passing through an inlet port 71 passes through, through this into the corresponding cylinder 62 entry. The inlet valve 17 is also driven to close, thereby forming a part of the combustion chamber during the compression and power stroke of the four-stroke cycle.

The outlet valve 74 is in the cylinder head of a corresponding cylinder 62 installed and is made by a rotation of the camshaft 76 rotatably driven. In particular, the exhaust valve 74 driven to open, thereby allowing burned exhaust gas in the corresponding cylinder 62 out of the cylinder 62 escapes. The outlet valve 74 is also driven to close, thereby forming a part of the combustion chamber during the compression and power stroke of the four-stroke cycle.

The fuel tank 12 is designed to work with the feed pump 14 communicate and absorb fuel for combustion in each cylinder 62 is used.

The pump 14 is designed to work with the high pressure pump 16 to communicate. The pump 14 works in the fuel tank 12 stored fuel to pump the pumped fuel to the high pressure pump 16 to promote.

For example, the high-pressure pump 16 equipped with a drive shaft which is connected to the crankshaft to be rotatable with this. The high pressure pump 16 is also equipped with a piston installed in a cylinder and connected to the drive shaft. The piston is in a cylinder in synchronization with a rotation of, for example, the camshaft 76 reciprocable via the drive shaft between an upper compression dead center (TDC) and a lower compression dead center (BDC).

In the high pressure pump 16 that comes from the feed pump 14 pumped fuel into the regulating valve 18 a, so that its flow rate through the regulating valve 18 is set. The regulated flow rate fuel is delivered to a compression chamber of the cylinder while the piston is delivered from the TDC to the BDC in synchronization with rotation of the camshaft 76 is moved.

Subsequently, while the piston from the BDC to the TDC in synchronization with a rotation of the camshaft 76 is moved, the fuel stored in the compression chamber is pressurized by the piston, so that the pressurized fuel in the pressure accumulator 20 is encouraged.

The accumulator 20 is designed, for example, as a common rail, which is constructed, for example, from a series of storage sections, which are connected by tubes with a small bore. The accumulator is hereinafter referred to as "common rail".

The common rail 20 is designed to work with each cylinder 62 over a high pressure fuel passage 17 and a corresponding injector 30 to communicate so they are from the cylinders 62 is shared.

The common rail 20 is operable to store in itself the high-pressure fuel from the high-pressure pump 16 is delivered, wherein the pressure is kept high.

In particular, the fuel injection system has a pressure sensor 22 , The pressure sensor 22 is partly in the common rail 20 installed and developed the pressure of a fuel in the common rail 20 recorded continuously or repeatedly. The pressure sensor 22 is electric with the ECU 40 Connected and is operable to take a reading of the pressure of the common rail 20 stored fuel to the ECU 40 to send. The pressure of in the common rail 20 stored fuel passing through the pressure sensor 22 is hereinafter referred to as a "rail pressure".

The regulating valve 18 is electric with the ECU 40 connected. Under a control of the ECU 40 the regulating valve works 18 to adjust the amount of fuel coming from the feed pump 14 is encouraged to enter the compression chamber of the high pressure pump 16 thereby to control the rail pressure so that the rail pressure coincides with a target pressure generated by the ECU 40 is preset.

The common rail 20 is also operable to uniformly store the high pressure fuel stored in it to the individual injectors 30 over the respective high pressure fuel passages 17 to promote.

Each of the injectors 30 is at its distal end in the combustion chamber of a corresponding cylinder 62 installed, which allows the pressurized fuel is injected directly into the combustion chamber.

Regarding 3 is the injector 30 in particular, essentially from a substantially cylindrical housing 30a , The housing 30a is inside with a hollow chamber 30b formed, which is arranged in its longitudinal direction. The housing 30a is also at its center on an inner peripheral wall of its one end (fuel injection end) with a valve seat 30c educated. The valve seat 30c has fuel injectors 34 connected to the exterior of the injector 30 and with the hollow chamber 30b are in communication.

The injector 30 consists essentially of a nozzle needle (needle valve) 32 in the hollow chamber 30b is installed. The nozzle needle 32 is arranged around the fuel injectors 34 open and close.

The nozzle needle 32 is biased by a pressure of a fuel in a compression chamber 100 stored in the housing 30a is formed so that it is on the valve seat 30c is set to the fuel injectors 34 close. The high-pressure fuel is from the common rail 20 in the compression chamber 100 and the hollow chamber 30b applied.

The injector 30 It also consists essentially of a solenoid or a piezoelectric valve actuator 36 with a valve element arranged to be in a low pressure passage 37 open and close in the housing 36a is trained and with the compression chamber 100 connected is. The valve actuator 36 is electric with the ECU 40 connected.

In particular, the valve actuator works 36 a particular injector 30 if it is through the ecu 40 is energized to move the valve member to the low pressure passage 37 to open. This allows the pressure of a fuel in the compression chamber to be reduced 100 is included.

The reduction of the pressure in the compression chamber 100 stored fuel allows the nozzle needle 32 from the valve seat 30c against the bias of the pressure of one in the compression chamber 100 stored fuel, thereby the fuel injection nozzles 34 to open. This leads to an injection of the common rail 20 subsidized fuel through the fuel injectors 34 into the combustion chamber of a corresponding cylinder 62 ,

In contrast, when a power supply to the valve actuator 36 is interrupted, the valve actuator works 36 of the particular injector 30 to move the valve member to the low pressure passage 37 close. This allows the pressure of the fuel, which is in the compression chamber 100 is rising.

The increase in the pressure of the in the compression chamber 100 stored fuel allows the nozzle needle 32 by the bias of the pressure in the compression chamber 100 stored fuel toward the valve seat 30 falls, thereby injecting the fuel injectors 34 close. This results in stopping the injection of fuel from the common rail 20 is conveyed into the combustion chamber of a corresponding cylinder 62 ,

In particular, as described above, the injector is 30 designed to inject fuel during the energization period when energized. In other words, the ECU works 40 to go to the injector 30 to apply a pulse current having a pulse width (pulse duration) corresponding to the energization duration.

Therefore, control of the pulse width of the pulse current applied to the injector 30 is to apply a quantity of fuel from the injector 30 is to be injected, set to a target injection amount. The Energiebeaufschlagungsdauer for the injector 30 hereinafter also referred to as "current pulse width". The current pulse width for the injector 30 is used as an instruction value corresponding to the injector 30 for injecting a target fuel amount corresponding to the instruction value is to be output.

Regarding 2 is the ECU 40 with a microcomputer 50 and its peripherals integrated. The microcomputer 50 consists of a CPU 52 , a ROM 54 , a ram 56 , an EEPROM 58 as an example of non-volatile memory, various I / O ports (input and output ports), etc.

At least one control program is foreseen for the ECU 40 (CPU 52 ) as a calculation module 52a for actual IQ characteristic data, a characteristic point detection module 52b , a phase difference calculation module 52c , a phase correction module 52d and a fuel injection correction module 52e to work.

In this embodiment, a characteristic showing the relationship between an interval duration and a pressure pulsation for each injector 30 is measured in advance, and IQ reference characteristic data F is determined in advance over an entire time range usable for the interval duration on the basis of the measured characteristic in, for example, a map format or a function formula format. The IQ reference characteristic data F in advance, for example, in the EEPROM 58 , the ROM 54 and / or the RAM 56 the ECU 40 saved.

When the I-Q reference characteristic data F is determined in the map format, a quick determination can be made as compared with a determination in the functional formula format. In contrast, when the I-Q reference characteristic data F is determined in the functional formula format, it can reduce a memory capacity required to store the I-Q reference characteristic data F as compared with those determined in the map format.

In the map format, the I-Q reference characteristic data F is determined for each predetermined printing area; these predetermined pressure ranges form a predetermined acceptable pressure range for the rail pressure. In the functional formula format, the I-Q reference characteristic data F is determined as a function of the rail pressure.

The I-Q reference characteristic data establishes a reference relationship between a target interval duration from an earlier injection by an injector to a later injection following the previous injection and a correction value of an amount of fuel actually injected by the injector in the later fuel injection.

In particular, if a target interval duration between an earlier injection and a later injection, which is through an injector 30 in the multiple injection mode is executed, the ECU operates 40 to refer to the IQ reference characteristic data according to the actually measured rail pressure to obtain a correction value corresponding to the set target interval duration. Thus, the ECU corrects 40 on the basis of the correction value, an instruction value corresponding to a target fuel amount for the later injection, and outputs the corrected instruction value to the injector 30 out. This allows a quantity of fuel that is actually from the injector 30 is injected with the target fuel quantity for later injection coincides.

The fuel injection system 10 has a machine speed sensor 80 , an accelerator sensor (throttle position sensor) 81 , a temperature sensor 82 and other sensors 83 ; these sensors 80 . 81 . 82 and 83 are used to measure parameters representing the operating conditions of the diesel engine 60 and indicate the driving conditions of the motor vehicle.

The engine speed sensor 80 is electric with the ECU 40 Connected and operable to data representing a speed of the diesel engine 10 indicate, based on a crank angle of the crankshaft 66 and the measured data as an engine speed to the ECU 40 issue.

The accelerator sensor 81 is electric with the ECU 40 connected. The accelerator sensor 81 is operable to measure an actual position or stroke of an accelerator pedal of the engine-powered vehicle operable by the driver and the measured actual stroke or position of the accelerator pedal as data representative of a driver's torque request (torque increase request or torque reduction request) the diesel engine 60 to the ECU 40 issue.

The temperature sensor 82 is electric with the ECU 40 connected and operable to continuously or periodically measure data indicative of a temperature of an engine coolant and to continuously or periodically measured data to the ECU 40 issue.

Each one of some of the other sensors 83 is operable to measure a current value of a corresponding parameter representing the operating conditions of the diesel engine 60 and the measured value of a corresponding parameter to the ECU 40 issue.

Each of the remaining sensors 83 is operable to measure a current value of a corresponding parameter indicating the driving conditions of the engine-powered vehicle and the measured value of a corresponding parameter to the ECU 40 issue.

The ECU 40 is operable to:
Parts of data passing through the sensors 22 . 80 . 81 . 82 and 83 measured and sent by them to receive; and
based on the operating conditions of the diesel engine 60 which are determined by at least some of the received pieces of data transmitted by the sensors 22 . 80 . 81 . 82 and 83 be measured, different actuators in the diesel engine 60 are installed and the injectors 30 and the regulating valve 18 include, thereby controlling various control variables of the diesel engine 60 adjust.

In particular, the ECU 40 programmed to:
the target pressure for the rail pressure based on the operating conditions of the diesel engine 60 which are determined by at least some of the received portions of data passing through the sensors 22 . 80 . 81 . 82 and 83 be measured; and
the regulating valve 18 so that the rail pressure coincides with the calculated target pressure.

In addition, to reduce combustion noise and / or nitrogen oxide (NOx) emissions, the ECU 40 programmed to perform multiple injections (multiple fuel injections) including at least one main injection and at least one auxiliary injection, for example pilot injection, pilot injection, post injection and / or post injection before or after the main injection in a multiple injection mode.

In particular, the ECU 40 programmed to:
an appropriate target timing, a suitable target injection amount, and / or a suitable value of another operating parameter for each of the multiple injections by each of the injectors 30 based on the specific operating conditions of the diesel engine 60 to calculate; and
to each of the injectors 30 output an instruction value for a corresponding one of the target injection amounts calculated for each of the multiple injections at the appropriate target injection timing calculated for each of the multiple injections; this instruction value assigns each of the injectors 30 to inject the corresponding one of the target injection quantities.

4 schematically shows a relationship between temporally adjacent fuel injections through an injector 30 in the multiple injection mode and pressure pulsations occurring in the injector 30 occur. The pressure pulsations are caused due to water hammering in the injector 30 occurs at the moment when the nozzle needle 32 the fuel injectors 34 closes to stop the fuel injection shock in an earlier injection in the temporally adjacent fuel injections.

Specifically, the ECU gives 40 in the multi-injection mode to the injector 30 a pulse current having a current pulse width corresponding to a target injection amount as the instruction value for the earlier injection. The pulse current causes the nozzle needle 32 of the injector 30 the fuel injectors 34 over the valve actuator 36 opens to thereby the target fuel quantity in a corresponding cylinder 62 than to inject the earlier injection (see t1 in 4 ).

Thereafter, when a duration corresponding to the current pulse width of the current pulse has elapsed since the start of supplying the pulse current, the ECU stops 40 the supply of pulse current to the injector 30 , This causes the nozzle needle 32 of the injector 30 the fuel injectors 34 closes, thereby injecting fuel into the corresponding cylinder 62 to stop (see t2 in 4 ).

At the moment when the nozzle needle 32 the fuel injectors 34 closes, a water hammer occurs in the injector 30 resulting in pressure pulsations in the injector 30 leads (see 4 ).

After an instruction interval period has elapsed since the falling edge of the pulse stream for the earlier injection, the ECU outputs 40 to the injector 30 a pulse current having a current pulse width corresponding to a target injection amount as the instruction value for the later injection. The pulse current causes the nozzle needle 32 of the injector 30 the fuel injectors 34 by means of the valve actuator 36 opens to thereby the target fuel quantity in a corresponding cylinder 62 as injecting the later injection (see t3 in 4 ).

The pressure pulsations affect a valve opening / closing timing of the injector 30 , The magnitude of the pressure pulsations depends on an elapsed time since the stop of the fuel injection stroke in the earlier injection.

Regarding 5 is the closing timing of the nozzle needle 32 in the earlier injection by a time Tde1 with respect to the falling edge (decay timing) of the current pulse for the earlier injection. In addition, the opening timing of the nozzle needle 32 delayed in the later injection by a time Tds1 relative to the rising edge (rise time adjustment) of the current pulse for the later injection.

Thus, it is necessary to preset the delay time Tde1 and the delay time Tds1 to determine a target interval duration on the basis of the instruction interval duration and the two preset delay times Tde1 and Tds1.

For example, the target interval duration is expressed by the following equation [1]: Pt = Pi - Tde1 + Tds1 [1] where Pt represents the target interval duration and Pi represents the instruction interval duration.

However, a fall timing of injection rate of an injector (target injector) changes 30 in the earlier injection and a rise timing of the injection rate of the target injector 30 in the later injection due to its manufacturing variations and its aging. For example, the decay timing is the injection rate of the target injector 30 delayed in the earlier injection relative to a particular decay timing of the injection rate thereof (see reference numeral " 210 "). Similarly, the rise time adjustment is the injection rate of the one injector 30 delayed in the later injection relative to a particular rise time adjustment of the injection rate thereof (see reference numeral " 212 ").

The delay of the decay timing of the target injector 30 relative to the particular fall timing causes changes in the delay time of the closing timing of the nozzle needle 32 from the preset value Tde1 to a value Tde2. Likewise, the delay causes the rise time adjustment of the target injector 30 relative to the particular rise time adjustment, changes in the delay time of the open timing of the nozzle needle 32 from the preset value Tds1 to a value Tds2.

Thus, the target interval duration is out of phase with an actual interval duration around the sum of a time length ΔINT1 and a time length ΔINT2 at the timing of starting the later injection; this sum of the time length ΔINT1 and the time length ΔINT2 is expressed by "ΔINT1 + ΔINT2". The time length ΔINT1 corresponds to a difference of the preset delay time Tde1 from the delay time Tde2, and the time length ΔINT2 corresponds to a difference of the delay time Tds2 from the preset delay time Tds1.

As in 5 In particular, an actual IQ characteristic, which is a relationship between an actual interval duration from the previous injection by the target injector, is illustrated 30 to the later injection and a correction value of one of the target injector 30 actual injected fuel quantity in the later injection indicates the time length "ΔINT1 + ΔINT2" out of phase with the IQ reference characteristic.

Now, suppose that the phase difference between the I-Q reference characteristic and the actual I-Q characteristic is not taken into consideration.

In this assumption, if a value Pt1 of the target interval duration between the earlier injection and the later injection by the injector 30 is set, a correction value would be at one point 220 of the IQ reference characteristic corresponding to the set value Pt1 of the target interval period. Thus, an instruction value corresponding to the target injection amount for the later injection would be based on the correction value at the point 220 the IQ reference characteristic are corrected.

However, a value Pa1 is the actual interval duration between the earlier injection and the later injection by the injector 30 shorter than the value Pt1 of the target interval duration by the time length "ΔINT1 + ΔINT2". For this reason, the correction value differs at the point 220 the IQ reference characteristic of a correction value at a point 222 the actual IQ characteristic corresponding to the value Pa1 of the actual interval duration; this correction value at the point 222 The actual IQ characteristic should be used to correct an instruction value corresponding to the target injection amount for the later injection.

This can reduce the accuracy of correcting an amount of fuel that is actually from the injector 30 is injected.

In contrast, the fuel injection system 10 According to the embodiment, designed to account for the phase difference between the IQ reference characteristic and the actual IQ characteristic.

In particular, as described above and in 1A and 1B 3, the characteristics of the pressure pulsations in an injector for respective different target injection quantities are substantially coincident with each other irrespective of an interval duration between the stop of injecting fuel in a previous injection and the start of injecting fuel in a later injection, the earlier one Injection follows.

Moreover, when a plurality of sets of first and second fuel injection pulses are executed in the multiple injection mode while a target interval duration between the first injection pulse and the second injection pulse of each set is changed such that:
a target injection quantity for the first injection shot from each set differs from that for the first injection shot of another set;
a target injection amount for the second injection stroke of each set is the same as that for the second injection shot of another set; and
a timing of stopping the first injection stroke of each set is the same as that of stopping the first injection stroke of another set, then curves of fuel amounts "Q" actually of. the injector 30 are injected by the plurality of sets of first and second fuel injection pulses, substantially identical to the change of the target interval duration.

Specifically, a variation of an amount of fuel actually depends on the injector 30 injected by a later injection that follows an earlier injection in the multiple injection mode, greatly depends on a variation of an actual interval duration between the earlier and the later injection.

Thus, even if an actual interval duration varies between an earlier injection and a later injection in the multi-injection mode, an actual IQ characteristic differs from each of the injectors 30 in one phase from the IQ reference characteristic.

Moreover, even if measurement errors are included in the actual I-Q characteristic data, the actual I-Q characteristic data may deviate from the I-Q reference characteristic data only in a magnitude offset direction.

For this reason, the fuel injection system 10 according to the embodiment, to work in a learning mode to:
to calculate a phase difference between the IQ reference characteristic and an actual IQ characteristic actually generated by the ECU 40 is calculated as described below; and
correct the IQ reference characteristic such that the IQ reference characteristic is shifted by the calculated phase difference, thereby matching the corrected IQ reference characteristic with the actual IQ characteristic.

The corrected IQ reference characteristic allows the ECU 40 operating in the multiple injection mode corrects an amount of fuel that is actually injected from a later injection following an earlier injection executed in the multiple injection mode.

Next, operations of the ECU will be described below 40 described according to the embodiment.

At least one of the stores 58 . 54 and 56 the ECU 40 like the EEPROM 58 in the embodiment, serves as a memory module that stores in advance the IQ reference characteristic data F at the time of shipment of the fuel injection system, for example 10 be determined.

More specifically, the IQ reference characteristic data F represents a reference relationship between a variable of a target interval duration from an earlier injection by each of the injectors 30 to a later injection following the previous injection, and a variable of a correction amount of fuel quantity received from a corresponding one of the injectors 30 is actually injected in the later injection; this variable of the target interval duration belongs to a total time range which is usable for the target injection duration.

Specifically, the correction value is the amount of fuel supplied by an injector 30 is actually injected, for example, determined as a correction value of the decay timing of a current pulse applied to the injector 30 to be applied in the later injection; this current pulse controls the amount of fuel flowing from the injector 30 actually injected in the later injection. A correction of the decay timing of the current pulse applied to the injector 30 is applied in the later injection, allows adjustment of a current pulse width of the current pulse, whereby the amount of fuel is changed by the injector 30 is actually injected in the later injection.

The sign of the correction value in the IQ reference characteristic data at a certain value of the target interval duration is positive when an amount of fuel that is actually from an injector 30 is injected, and that corresponds to the determined value of the target interval duration, is lower than a corresponding target injection amount. Moreover, the sign of the correction value in the IQ reference characteristic data at a certain value of the target interval duration is negative when an amount of fuel that is actually from an injector 30 is injected and corresponds to the determined value of the target interval duration is higher than a corresponding target injection amount.

For example, the IQ reference characteristic data F becomes for each injector 30 determined while this is set, and in the EEPROM 58 saved.

The ECU 40 is programmed to start and execute a routine (learning routine), for example in the RAM 56 saved and in 6 is always shown at a predetermined cycle during the diesel engine 60 running.

• (A) Eine durch die ECU 40 bestimmte Zieleinspritzmenge ist gleich zu oder niedriger als Null; und
• (B) die tatsächliche Beschleunigerposition oder ein Hub des Gaspedals ist auf der Basis der durch den Beschleunigersensor 81 gemessenen Daten auf Null festgelegt.

When the learning routine is started during execution of the fuel injection control mode, the CPU is used 52 as the calculation module 52a for the actual IQ characteristic data to determine in step S400 whether the following learning authorization conditions are satisfied:

• (A) One by the ECU 40 certain target injection amount is equal to or lower than zero; and
• (B) the actual accelerator position or a lift of the accelerator pedal is based on the accelerator sensor 81 measured data to zero.

It should be noted that the circumstances that the target injection amounts are set lower than zero will be described below.

Specifically, a current pulse width is that of a particular injector 30 applied pulse current corresponding to "zero" of the target injection amount has been determined; this current pulse width is hereinafter referred to as a "zero injection pulse width". Thus, when the pulse stream with the zero injection pulse width to a particular injector 30 is applied, the amount of fuel should actually be from the particular injector 30 usually becomes zero.

However, a fuel injection characteristic of an injector may become 30 due to its manufacturing variation and / or its aging, differ from a corresponding reference fuel injection characteristic. For this reason, it may be when the pulse current with the zero injection pulse width on a particular injector 30 that is applied by the particular injector 30 actually injected fuel quantity does not become zero. In other words, although the target injection amount is set to zero, the particular injector may 30 inject a quantity of fuel.

It is believed that an injector 30 such a fuel injection characteristic has that the amount of fuel actually injected therefrom is not zero when the target injection amount of zero is set for it.

In this assumption, the amount of fuel actually from the injector 30 is set to zero, the ECU works 40 to go to the injector 30 apply the pulse current with a current pulse width corresponding to a negative value of the target injection amount; this current pulse width is shorter than the zero injection pulse width. This allows the amount of fuel actually from the injector 30 is injected, becomes zero.

Upon determining that the learning authorization conditions are satisfied (YES in step S400), the CPU goes 52 to step S402, and otherwise (NO in step S400), the learning routine is ended.

In step S402, the CPU operates 52 in a learning mode to an injector (target injector) 30 instructing to select a first target fuel amount in a first injection based on the learning authorization conditions-fulfilling timing as a learning injector.

After a preset measurement point of a target interval duration has elapsed since the stop of injecting fuel in the first injection, the CPU instructs 52 the target injector 30 to inject a second target fuel quantity in a second injection.

In step 402, the CPU repeatedly executes a set of the first injection and the second injections while changing the measurement point of the target interval duration within at least a portion of the total time range usable for the target interval duration (see 402a of step S402).

In step S402, the CPU measures 52 an increase amount of the rotational speed of the crankshaft 66 by each set of the first and second injections based on the measured data of the engine speed sensor 80 (see 402b of step S402). The CPU 52 Also measures an engine speed at the timing of each set of the first and second injections based on the measured data of the engine speed sensor 80 (see 402c of step S402).

In step S402, the CPU calculates 52 as a torque proportional amount for each measurement point in the at least one portion of the target interval duration, the product of the measured increase amount of the rotational speed of the crankshaft 66 and the measured engine speed (see 402d of step S402).

The CPU 52 estimates an engine torque for each measurement point therefrom based on the torque proportional amount for each measurement point in the at least a portion of the target interval duration, thereby, based on the estimated engine torque for each measurement point in the at least a portion of the target interval duration, performs an actual injection amount for each measurement point estimate a corresponding set of the first and second injections (402e of step S402).

In step S402, the CPU calculates 52 at each measurement point of the at least a portion of the target interval duration, a correction value of the decay timing of a current pulse that in the second injection is to the target injector 30 based on the estimated actual injection amount for each measurement point in the at least one portion of the target interval duration (402f of step S402).

In step 402f of step S402, the CPU generates 52 actual IQ characteristic data based on the correction value of the fall timing of the current pulse applied to the target injector 30 in the second injection, at each measurement point in the at least one portion of the target interval duration.

The correction value at each measurement point in the at least a portion of the target interval duration allows the amount of fuel actually delivered by the target injector 30 is injected with the target injection quantity for the second injection at the corresponding measurement point in the at least a portion of the target interval duration.

Next is the CPU 52 in step S404 as the characteristic point detection module 52b to detect at least one characteristic point of the generated actual IQ characteristic data; this at least one characteristic point is estimated to be within the at least one portion S of the target interval duration.

Thus, in step S406, the CPU is used 52 as the phase difference calculation module 52c , around:
to detect at least one corresponding characteristic point of the IQ reference characteristic data stored in the EEPROM 58 are stored; and
calculate a phase difference between the at least one characteristic point of the actual IQ characteristic data and the corresponding at least one characteristic point of the IQ reference characteristic data.

Then the CPU is used 52 in step S408 as the phase correction module 52d to correct the IQ reference characteristic data, thereby to shift the IQ reference characteristic data by the calculated phase difference such that the IQ reference characteristic data coincides with match the actual IQ characteristic data.

Next, the CPU saves 52 in step S408, the corrected IQ reference characteristic data in, for example, the EEPROM 58 and ends the learning routine.

7 schematically shows a graphical representation 300 the IQ reference characteristic data and a graphical representation of parts 305 the actual IQ characteristic data at the respective measuring points (see marks "X" in 7 ) in the at least one portion (see reference character "S" in FIG 7 ) of the target interval duration. In other words, each of the actual IQ characteristic data and the IQ reference characteristic data periodically varies with a change in the target interval duration in the positive direction and in the negative direction, while the amplitude thereof is gradually decreased. Each of the parts 305 The actual IQ characteristic data represents a correction value of the fall timing of the current pulse applied to the injector 30 in the later injection is applied.

As in 7 is illustrated, the at least one portion S of the target interval duration is determined in step S402a such that at least one characteristic point of the actual IQ characteristic data corresponding to at least one characteristic point of the IQ reference characteristic data is estimated to be in the at least one section S. ,

Specifically, it should be noted that the phase difference between the I-Q reference characteristic data and the actual I-Q characteristic data does not vary suddenly over time. For this reason, based on the calculated phase difference between the IQ reference characteristic data and the actual IQ characteristic data as the result of execution of the previous learning routine, the location of at least one characteristic point of the actual IQ characteristic data estimated to be at least one characteristic point of the IQ Reference characteristic data corresponds.

Thus, in step S402a of the existing learning routine, at least a portion S of the target interval duration is determined on the basis of the estimated location of at least one characteristic point of the actual I-Q characteristic data such that the estimated location of the at least one characteristic point lies within the at least one section S.

How the at least one characteristic point of the actual I-Q characteristic data is detected will be described below.

As in 7 may be at least one point from a local maximum point 310 , a local minimum point 312 and a zero correction point 314 the count of the IQ reference characteristic data may be used as at least one characteristic point of the actual IQ characteristic data.

It should be noted that the zero correction point 314 of the IQ reference characteristic data is a characteristic point where the target injection quantity for the second injection is in accordance with the amount of fuel discharged from the injector 30 actually inject in the second injection. For this reason, one is to the zero correction point 314 corresponding correction value of the decay timing of the current pulse applied to the injector 30 to apply in the later injection is zero.

Each of the characteristic points (local maximum point 310 , local minimum point 312 and zero correction point 314 ) has a locally specific characteristic in the IQ reference characteristic data, so that it is easily identifiable in the IQ reference characteristic data as compared with another point in them.

Thus, in the embodiment, it is unnecessary for the ECU 52 obtains a large number of pieces of the actual total time domain IQ characteristic data usable for the target interval duration to detect a local maximum point, a local minimum point, and a zero correction point of the actual IQ characteristic data.

In other words, as described above, the CPU is 52 of the embodiment is configured to obtain a plurality of pieces of the actual IQ characteristic data within at least a portion S of the total time range usable for the target interval duration.

For example, the CPU determines 52 in 7 at least a portion S of the total time domain such that:
a local maximum point 320 , a local minimum point 322 and a zero correction point 324 the actual IQ characteristic data corresponding to the local maximum point 310 , the local minimum point 312 or the zero correction point 314 are estimated to be within the at least one portion S in step S402a.

Then the CPU gets 52 a large number of parts of the actual IQ characteristic data within the determined at least one portion S of the total time range usable for the target interval duration.

Thus, in comparison with obtaining a plurality of pieces (correction values) of the actual IQ characteristic data within the overall time range, it is possible to reduce the number of parts of the actual IQ characteristic data required by at least one point from the local maximum point 320 , the local minimum point 322 and the zero correction point 324 capture.

For example, the local maximum point appears 320 as a characteristic peak (positive peak) in the waveform on the basis of the parts 305 the actual IQ characteristic data, and the local minimum point 322 appears as a characteristic low (negative peak) in the waveform based on the parts 305 the actual IQ characteristic data.

Because of this, if the local maximum point 320 When the at least one characteristic point is detected, the CPU easily finds a vertex (positive peak) of the waveform on the basis of the parts 305 the actual IQ characteristic data as the local maximum point 320 , which reduces incorrect detection of local maximum points.

In the same way, if the local minimum point 322 when the at least one characteristic point is detected, the CPU finds 52 easily a low (negative peak) of the waveform based on the parts 305 the actual IQ characteristic data as the local minimum point 322 , whereby a false detection of local minimum points is reduced.

Moreover, as stated above, the local maximum point appears 320 as a characteristic peak (positive peak) in the waveform on the basis of the parts 305 the actual IQ characteristic data, and the local minimum point 322 appears as a characteristic low (negative peak) in the waveform based on the pieces 305 the actual IQ characteristic data.

For this reason, even if the actual IQ characteristic data is shifted in a sizing direction due to measurement errors contained therein, the CPU finds 52 easily a vertex (positive peak) and / or a low (negative peak) of the waveform based on the parts 305 the actual IQ characteristic data as the local minimum point 322 ,

The zero correction point 324 The actual IQ characteristic data is a characteristic point where the target injection quantity for the second injection is in accordance with the amount of fuel supplied from the injector 30 actually inject in the second injection. Because of this, the CPU finds 52 easily the zero correction point 324 the actual IQ characteristic data by, for example, comparing the target injection quantity for the second injection with the amount of fuel actually from the injector 30 is to be injected and which is calculated at each measuring point. This reduces false detection of zero correction points.

Moreover, even if the waveform has a comparatively low amplitude based on the actual IQ characteristic data, the CPU finds 52 easily the zero correction point 324 the actual IQ characteristic data by, for example, comparing the target injection quantity for the second injection with the amount of fuel actually from the injector 30 is to be injected and which is calculated at each measuring point.

In comparison to the amount of fuel actually from the injector 30 at the local maximum point 322 inject is where the amount of fuel coming from the injector 30 is actually injected in the second injection, is greater than the target injection quantity for the second injection, the amount of fuel supplied by the injector 30 at the zero correction point 324 actually injected, low. For this reason, a combustion noise that is during execution of the plurality of sets of the first and second injections is around the zero correction point 324 compared to that which is reduced during execution of the plurality of sets of the first and second injections by the local minimum point 322 to capture.

If measurement errors are included in the actual IQ characteristic data, so that parts 305 the actual IQ characteristic data from the IQ reference characteristic data 300 in a sizing offset direction (see 8th ), can be a measuring point 326 which crosses the correction value of zero, as the zero correction point 324 be recorded.

To cope with this error, the CPU determines 52 at least a portion S of the total time domain such that:
the local maximum point 320 and the local minimum point 322 in step S402a to be located at both ends of the at least one portion S.

Then the CPU performs 52 in steps S402a to S402f, a set of the first injection and the second injection at each of the measurement points of the target interval duration within the specific at least one section S to thereby obtain a plurality of parts (correction values) 305a get the actual IQ characteristic data at the measurement points. After that the CPU calculates 52 in step S404, an average value 330 the obtained correction values 305a as the zero correction point 324 ,

This prevents the measuring point 326 that crosses the correction value of zero erroneously as the zero correction point 324 is detected.

Preferably, the CPU detects 52 in step S404, a plurality of characteristic points of the actual IQ characteristic data, such as the local maximum point 320 , the local minimum point 322 and the zero correction point 324 ; these characteristic points are estimated to be within the at least one portion S of the target interval duration.

In step S406, when at least one characteristic point of the actual IQ characteristic data is detected in step S404, the CPU detects 52 at least one characteristic point of the IQ reference characteristic data stored in the EEPROM 58 are stored, corresponding to the at least one characteristic point of the actual IQ characteristic data.

Next, the CPU calculates 52 in step S406, a phase difference between the at least one characteristic point of the actual IQ characteristic data and the corresponding at least one characteristic point of the IQ reference characteristic data. This allows the CPU 52 determines the calculated phase difference as the phase difference between the IQ reference characteristic data and the actual IQ characteristic data.

If, in step 404, a plurality of the characteristic points of the actual IQ characteristic data, the at least one of the local maximum point 320 , the local minimum point 322 and the zero correction point 324 to be detected, the CPU detects 52 in step S406, a plurality of characteristic points of the IQ reference characteristic data stored in the EEPROM 58 are stored, corresponding to the plurality of characteristic points of the actual IQ characteristic data.

Next, the CPU calculates 52 in step S406, a phase difference between each of the plurality of characteristic points of the actual IQ characteristic data and a corresponding one of the plurality of characteristic points of the IQ reference characteristic data. After that the CPU calculates 52 in step S406, an average value of the calculated phase differences to thereby determine the average value as the phase difference between the IQ reference characteristic data and the actual IQ characteristic data.

Specifically, it is assumed that errors occur in some phase differences between some characteristic points of the actual I-Q characteristic data and those of the I-Q reference characteristic data due to, for example, measurement errors of some characteristic points of the actual I-Q characteristic data.

Even if such errors occur, the CPU can 52 calculate an average value of the remaining phase differences between the remaining characteristic points of the actual IQ characteristic data measured accurately and corresponding characteristic points of the IQ reference characteristic data. This prevents adverse effects due to the measurement errors.

Moreover, it is assumed that an error occurs in a phase difference between a characteristic point of the actual I-Q characteristic data and that of the I-Q reference characteristic data due to, for example, a large measurement error of the one characteristic point of the actual I-Q characteristic data.

Even if such an error occurs, the CPU can 52 calculate an average value of the remaining phase differences between the remaining characteristic points of the actual IQ characteristic data measured accurately and corresponding characteristic points of the IQ reference characteristic data. This prevents adverse effects due to the large measurement error.

In step S408, the CPU corrects 52 the IQ reference characteristic data to thereby shift the IQ reference characteristic data by the calculated phase difference so that the IQ reference characteristic data coincides with the actual IQ characteristic data. Next, the CPU saves 52 For example, in step S408, the corrected IQ reference characteristic data is input to the EEPROM 58 ,

Then, when the multiple injection is required, the ECU serves 40 as the fuel injection correction module 52e to at least one injector 30 output a current pulse having a current pulse width corresponding to a predetermined target injection amount in an earlier injection; this current pulse has the at least one injector 30 on, the specific target injection amount for the earlier one Injection into a corresponding cylinder 62 inject.

Subsequently, the ECU takes 40 Referring to the corrected IQ characteristic data stored in the EEPROM 58 are stored to receive a correction value corresponding to a certain value of the target interval duration for the later injection.

Then the ECU corrects 40 a current pulse width of a current pulse applied to the at least one injector 30 is to be applied based on the received correction value; this current pulse width corresponds to a certain target injection quantity for the later injection.

Then, after the predetermined value of the target interval duration has elapsed since the falling edge of the previous injection current pulse, the ECU outputs 40 the corrected current pulse to the at least one injector 30 to thereby provide the at least one injector 30 to instruct to inject an amount of fuel in the later injection on the basis of the corrected current pulse.

This allows a quantity of fuel that is actually from the at least one injector 30 that matches the particular target amount with little effect on variations in an actual interval duration between the earlier and the later injection in the multiple injection.

As described above, the fuel injection system is 10 according to the embodiment designed to pay attention to the fact that:
even if an actual interval time between a temporally adjacent earlier and later injection in a multiple injection mode from a target interval duration due to variations (manufacturing variations) of injectors 30 and aging each injector 30 may differ, a deviation of an actual IQ characteristic from the IQ reference characteristic on the basis of the deviation of the actual interval duration substantially mainly in a phase except the size offset, the period or the amplitude occurs.

In particular, the fuel injection system 10 designed to correct the IQ reference characteristic data to shift a phase thereof such that the IQ reference characteristic data substantially coincides with the actual IQ characteristic data. This makes it possible to correct, based on the corrected IQ reference characteristic data, an amount of fuel actually injected from the later injection following the earlier injection in the multiple injection mode.

This achieves an effect that an amount of fuel actually injected from the later injection subsequent to the previous injection in the multiple injection mode is corrected with high accuracy over a cumulative time range used for the target injection period.

Specifically, in the embodiment, the fuel injection system 10 developed to:
detect at least one characteristic point of the actual IQ characteristic data based on a plurality of pieces of the actual IQ characteristic data within a limited portion S of the total time range; and
calculate the phase difference between the actual IQ characteristic data and the IQ reference characteristic data by merely calculating the phase difference between the at least one characteristic point of the actual IQ characteristic point and a corresponding at least one characteristic point of the IQ reference characteristic point.

Thus, it is unnecessary for the fuel injection system 10 obtains a large number of pieces of the actual total time domain IQ characteristic data usable for the target interval period to detect at least one characteristic point and calculate the phase difference between the actual IQ characteristic data and the IQ reference characteristic data.

This achieves an effect that an amount of fuel that is actually injected from a later injection following previous injection in the multiple injection mode is corrected with high accuracy over a cumulative time range used for the target injection period while decreasing a learning amount, which is required before the learning is finished.

The fuel injection system 10 can be developed to:
detect at least one characteristic point of the actual IQ characteristic data based on a plurality of pieces of the actual IQ characteristic data within the overall time range; and
merely calculate the phase difference between the actual IQ characteristic data and the IQ reference characteristic data by calculating the phase difference between the at least one characteristic point of the actual IQ characteristic point and a corresponding at least one characteristic point of the IQ reference characteristic point.

In the embodiment, the fuel injection system is configured to correct for the fall timing of the current pulse being applied to a target injector 30 in a later injection following a previous injection in the multiple injection mode to thereby correct the current pulse width of the current pulse. This leads to the correction of an amount of fuel supplied by the target injector 30 is actually injected in the later injection. However, the present invention is not limited to the structure.

Specifically, the fuel injection system may be configured to provide injection timing of a target injector 30 in the later injection in the multiple injection mode, thereby correcting an amount of fuel discharged from the target injector 30 actually injected in the later injection.

In the embodiment, as the IQ reference characteristic data and the actual IQ characteristic data, a reference relationship between a target interval duration from a previous injection by each injector 30 to a later injection following the earlier injection and a correction amount of fuel actually received from a corresponding injector 30 injected in the later injection.

However, as the IQ reference characteristic data and the actual IQ characteristic data, a reference relationship between a target interval duration may be from a previous injection by each injector 30 to a later injection following the previous injection and a correction value of a total amount of fuel delivered by a corresponding injector 30 in both the earlier injection and the later injection is actually injected.

As temporally adjacent fuel injections (earlier injection and later injection), in the multiple injection mode, some of a plurality of fuel injection bursts adjacent to each other in time may be combined.

The learning routine may be executed at each rail pressure within the predetermined acceptable pressure range intended for it.

A pressure limiter can be used in the common rail 20 be installed. The pressure limiter is operable to operate in the common rail 20 stored fuel, thereby reducing the rail pressure such that the rail pressure does not exceed a preset upper limit. Instead of or in addition to the pressure limiter, a pressure reducing valve for reducing the rail pressure under control of the ECU 40 be used.

In the embodiment, as the internal combustion engine, the diesel engine 60 but the present invention is not limited to the structure. Specifically, a spark-ignited gasoline engine such as a direct-injection gasoline engine may be used as the internal combustion engine.

In an apparatus, an actual fuel injection characteristic obtaining unit obtains an actual fuel injection characteristic of an injector with respect to a variable of a target interval duration within at least a portion in a usable range. A characteristic point detection unit detects at least one characteristic point of the actual fuel injection characteristic of the injector. The at least one characteristic point has a locally specific characteristic in the actual fuel injection characteristic of the injector. A phase difference calculating unit calculates a phase difference between a reference fuel injection characteristic and the obtained actual fuel injection characteristic based on the at least one characteristic point of the actual fuel injection characteristic and the at least one characteristic point of the reference fuel injection characteristic corresponding to the at least one characteristic point of the actual fuel injection characteristic.

Claims (9)

Apparatus for controlling an injector in a multiple injection mode to inject an amount of fuel into an internal combustion engine in an earlier injection and to control the injector after a target interval duration has elapsed to inject fuel into the internal combustion engine in a later injection, the apparatus comprising a storage unit configured to store therein a reference fuel injection characteristic of the injector with respect to a target interval duration within a usable range determined for the target interval duration, the target interval duration being an interval between stopping fuel injection by the injector in the earlier injection and represents a start of fuel injection by the injector in the later injection, wherein the reference fuel injection characteristic depends on at least a quantity of fuel supplied from the injector in the injector injected later injection; and an actual fuel injection characteristic obtaining unit configured to obtain an actual fuel injection characteristic of the injector with respect to the target interval duration within at least a portion in the usable range; the apparatus being characterized by a characteristic point detecting unit configured to detect at least one characteristic point of the actual fuel injection characteristic of the injector, the at least one characteristic point having a locally specific characteristic in the actual fuel injection characteristic of the injector; a phase difference calculating unit configured to calculate a phase difference between the reference fuel injection characteristic and the obtained actual fuel injection characteristic based on the at least one characteristic point of the actual fuel injection characteristic and at least one characteristic point of the reference fuel injection characteristic corresponding to the at least one characteristic point of the actual fuel injection characteristic; a phase correcting unit configured to shift the reference fuel injection characteristic by the calculated phase difference so as to correct the reference fuel injection characteristic so as to approximate the obtained actual fuel injection characteristic; and a fuel injection correction unit configured to control the injector based on the corrected reference fuel injection characteristic to correct an amount of fuel injected from the injector in the later injection. The apparatus of claim 1, wherein the actual fuel injection characteristic obtaining unit is configured to operate in a learning mode to: a first injection that outputs an instruction value to the injector, the instruction value instructing the injector to inject a first target fuel amount; and a second injection that, after a value of the target interval duration has elapsed since a stop of fuel injection by the injector in the first injection, outputs an instruction value to the injector, the instruction value instructing the injector to inject a second target fuel amount in a second injection; and repeating a set of the first and second injections while changing the value of the target interval duration within the at least one portion of the usable range, and wherein the actual fuel injection characteristic obtaining unit is configured to obtain the actual fuel injection characteristic of the injector with respect to the target interval duration within the at least one portion in the usable range based on a result of repeating the set of the first and second injections. An apparatus according to claim 1 or 2, wherein the phase difference calculating unit is configured to calculate, as the phase difference between the reference fuel injection characteristic and the obtained actual fuel injection characteristic, a phase difference between the at least one characteristic point of the actual fuel injection characteristic and the at least one characteristic point of the reference fuel injection characteristic Characteristic point of the actual fuel injection characteristic corresponds. An apparatus according to any one of claims 1 to 3, wherein the actual fuel injection characteristic has a local maximum point and a local minimum point, and the at least one characteristic point of the actual fuel injection characteristic is at least one of the local maximum point and the local minimum point. An apparatus according to any one of claims 1 to 3, wherein the at least one characteristic point of each of the actual fuel injection characteristic and the reference fuel injection characteristic is a point at which an amount of fuel actually injected by the injector and a target amount of fuel to be injected from the injector coincide with each other. The apparatus of claim 5, wherein each of the actual fuel injection characteristic and the reference fuel injection characteristic represents a ratio between a correction amount of an amount of fuel actually injected from the injector in the later injection and the target interval duration, and the at least one characteristic point of each of the actual fuel injection characteristic and the reference fuel injection characteristic is a point at which the correction value is zero. An apparatus according to any one of claims 1, 2 and 4 to 6, wherein the at least one characteristic point of the actual fuel injection characteristic includes a plurality of characteristic points, the at least one characteristic point of the reference fuel injection characteristic includes a plurality of characteristic points corresponding to the plurality of characteristic points of the actual fuel injection characteristic, respectively , and the phase difference calculating unit is configured to calculate the phase difference between the reference fuel injection characteristic and the obtained actual fuel injection characteristic based on the plurality of characteristic points of the actual fuel injection characteristic and the plurality of characteristic points of the reference fuel injection characteristic respectively to the plurality of Characteristic points of the actual fuel injection characteristic correspond. Apparatus according to claim 7, wherein the phase difference calculation unit is configured to: calculate a phase difference between each of the plurality of characteristic points of the actual fuel injection characteristic and a corresponding one of the plurality of characteristic points of the reference fuel injection characteristic; and as the phase difference between the reference fuel injection characteristic and the obtained actual fuel injection characteristic, calculate an average value of the calculated phase differences between the plurality of characteristic points of the actual fuel injection characteristic and the plurality of characteristic points of the reference fuel injection characteristic. Fuel injection system with: a pressure accumulator; a fuel pump configured to pressurize a fuel and deliver the pressurized fuel to the accumulator so that the pressurized fuel is stored in the accumulator; an injector for injecting the fuel stored in the accumulator into a cylinder of an internal combustion engine; and A device according to one of claims 1 to 8.

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