JP4302665B2 - Fuel injection control method, fuel injection valve, and fuel injection control device - Google Patents

Description

  The present invention relates to a fuel injection control method for adjusting an operation mode of an actuator for a fuel injection valve capable of continuously adjusting a lift amount of a nozzle needle according to displacement of the actuator. The present invention also relates to a fuel injection valve capable of continuously adjusting the lift amount of the nozzle needle according to the displacement of the actuator. Furthermore, the present invention relates to a fuel injection control device that controls a fuel injection rate by operating the actuator for a fuel injection valve capable of continuously adjusting a lift amount of a nozzle needle according to displacement of the actuator.

  It is well known that the amount of fuel injected by a fuel injection valve is set by a drive pulse width that drives an actuator provided in the fuel injection valve. However, each fuel injection valve has individual differences within a range of errors allowed at the time of manufacture. For this reason, even if the actuator of each fuel injection valve is driven by the same drive pulse, the fuel amount injected from each fuel injection valve varies.

  Therefore, in the past, as seen in, for example, Patent Document 1 below, the fuel injection amount by the fuel injection valve is actually measured, and the pulse width of the drive pulse is determined from the difference between the target injection amount and the measured injection amount. It has also been proposed to set a correction value. According to such correction of the pulse width of the drive pulse, the fuel injection amount of the fuel injection valve that controls the fuel injection amount by controlling the valve opening timing and the valve closing timing of the fuel injection valve is caused by the individual difference. Variations can be appropriately eliminated.

  By the way, in recent years, as can be seen in Patent Document 2 below, a fuel injection valve that can continuously adjust the lift amount of the nozzle needle according to the displacement of the actuator has been proposed. According to this fuel injection valve, since the lift amount of the nozzle needle during the fuel injection can be controlled, not only the fuel injection amount but also the fuel injection rate can be controlled. However, in such a fuel injection valve, even if the actuator is operated to a predetermined operation amount, the actual lift amount varies due to individual differences among the fuel injection valves. For this reason, although such a fuel injection valve can control the fuel injection rate, due to the individual difference, not only the fuel injection amount but also the fuel injection rate waveform varies.

And, when trying to compensate for the individual difference of such fuel injection valve by correcting the pulse width of the drive pulse, it is not possible to correct the lift state in the middle of the lift pattern that realizes the desired injection rate waveform, It is impossible to correct the desired injection rate waveform. In addition, as a technique for compensating for the variation in the fuel injection amount due to the solid difference of the fuel injection valve, there is a technique described in Patent Document 3, for example, in addition to the technique described in Patent Document 1.
JP 2002-201992 A US Pat. No. 6,520,423 JP 2003-120384 A

  The present invention has been made in order to solve the above-described problems, and the object of the present invention is to use a fuel injection valve capable of continuously adjusting the lift amount of the nozzle needle according to the displacement of the actuator. The purpose is to suitably control the fuel injection rate regardless of changes over time or the like.

  Hereinafter, means for solving the above-described problems and the operation and effects thereof will be described.

  According to the first aspect of the present invention, based on the fuel injection mode measured when the actuator is operated, at least one of the solid difference of the fuel injection valve and the change over time in relation to the displacement of the nozzle needle with respect to the operation amount of the actuator. Specific information resulting from the above, and adjusting the operation amount of the actuator to approximate the actual injection rate waveform by the fuel injection valve to the target injection rate waveform based on the acquired information Features.

  According to the fuel injection valve, the lift amount of the nozzle needle and the change speed thereof can be adjusted by adjusting the operation amount of the actuator and the change speed thereof, and as a result, the fuel injection targeting the fuel injection rate waveform. The rate waveform can be controlled. However, the relationship between the displacement of the nozzle needle with respect to the operation of the actuator reflects the difference in individual fuel injectors used and the change over time. The above relationship is reflected in the fuel injection mode such as the fuel injection amount and the fuel injection rate when the fuel is injected from the fuel injection valve. For this reason, it is possible to detect a difference in individual fuel injectors and a change with time from the fuel injection mode of each individual fuel injector. In the above method, using this property, it is possible to acquire unique information due to a solid difference or a change with time on the above relationship based on measurement of the fuel injection mode. Then, by using the unique information, adjustment of the operation amount that suppresses the variation in the fuel injection rate waveform that occurs when the common operation amount is set with the fuel injection valve of the same model without using the unique information. It becomes possible.

  Incidentally, it is desirable that the adjustment of the operation amount includes adjustment of the operation amount within the operation period of the actuator in one fuel injection (preferably, timing other than both ends of the period).

  According to a second aspect of the present invention, in the first aspect, the target injection rate waveform is an operation amount corresponding to an intermediate lift amount between a lift amount and a full lift amount at an injection rate of zero, and the operation amount is once set. It is realized by being fixed.

  In the above method, the operation amount is temporarily fixed at the operation amount corresponding to the intermediate lift amount. In such control, when trying to compensate for variations in lift amount due to individual differences or changes over time by adjusting the pulse width of the drive pulse of the fuel injection valve, this is realized by fixing the operation amount. The variation in the injection rate cannot be compensated. In this regard, in the above method, for example, the variation in the injection rate can be compensated through the adjustment of the fixed operation amount.

  According to a third aspect of the present invention, in the first or second aspect, the target injection rate waveform is realized by a lift waveform that sets a lift amount in multiple stages in one fuel injection. And

  In the above method, the lift amount corresponding to each of the multi-stage lift stages varies due to a change with time of the fuel injection valve and a difference in solids. This variation cannot be compensated for by adjusting the pulse width of the fuel injection valve drive pulse. On the other hand, in the above method, for example, the variation in the lift amount is compensated by adjusting the amount of operation within the operation period of the actuator in one fuel injection (preferably, timing other than both ends of the period). Can do.

  According to a fourth aspect of the present invention, in the third aspect, the operation amount of the actuator is adjusted for each operation amount corresponding to each of the multi-stage lift stages.

  In the above method, since each of the operation amounts corresponding to each of the multi-stage lift stages is adjusted based on the unique information, it is possible to suppress variations in the injection rate corresponding to each of the multi-stage lift stages. it can. For this reason, the actual injection rate waveform can be suitably approximated to the target injection rate waveform.

  In the invention of claim 5, in claim 4, the adjustment for each operation amount corresponding to each of the multi-stage lift stages, the operation amount serving as a reference for realizing the target injection rate waveform, This is performed by adjusting the value at each lift stage with the same adjustment amount.

  When the lift amount varies from the reference lift amount due to individual differences or changes over time, the magnitude relationship between the actual lift amount and the reference lift amount tends to be the same in each lift stage. That is, for example, if the actual lift amount is smaller than the reference lift amount at a certain lift stage, the actual lift amount tends to be smaller than the reference lift amount at another lift stage.

  In this regard, according to the above method, it is possible to easily and suitably suppress the variation in the actual lift amount at each lift stage in view of the above tendency.

  In the invention of claim 6, in claim 4, the adjustment for each operation amount corresponding to each of the multi-stage lift stages is performed with respect to the operation amount serving as a reference for realizing the target injection rate waveform. It is characterized in that it is carried out by adjusting the value at each lift stage by an independently determined adjustment amount.

  According to the above method, since the adjustment amount is set for each lift stage, variation in the actual lift amount at each lift stage can be suitably suppressed. This method is particularly effective when the relationship between the variation in the actual lift amount (injection rate) with respect to the reference and the operation amount has nonlinearity.

  According to a seventh aspect of the present invention, in the fifth or sixth aspect, the adjustment amount is set separately for each of a plurality of values for either the fuel injection period or the fuel injection amount.

  According to the above method, the power balance in the power transmission system when the power from the actuator is transmitted via the power transmission system from the actuator to the nozzle needle is determined by the fuel injection period (fuel injection amount). In view of the change depending on the injection amount, an appropriate adjustment amount corresponding to each injection period (injection amount) can be set.

  According to an eighth aspect of the present invention, in the seventh aspect of the present invention, the setting of the adjustment amount is performed by setting the fuel injection mode at each of several values before the fuel injection valve is mounted on an engine system. A process for creating an arithmetic expression for determining the relationship between any of the above and the adjustment amount based on the measurement of the above, and after the fuel injection valve is mounted on the system, any one of the values is substituted into the arithmetic expression And the process of setting the adjustment amount.

  In the above method, in consideration of the fact that the relation between the fuel injection period (injection amount) and the adjustment amount can be accurately approximated by an arithmetic expression, the above arithmetic expression is used when setting the adjustment amount after the fuel injection valve is mounted on the engine system. As a result, the amount of stored data stored in the control system of the engine system can be reduced.

  According to a ninth aspect of the present invention, in any one of the fifth to eighth aspects, the fuel injection valve injects fuel in a pressure accumulation chamber that stores fuel in a high-pressure state, and the adjustment amount is set in the pressure accumulation chamber. Each of the plurality of values for the fuel pressure is set separately.

  According to the above method, the balance of force in the power transmission system when the power from the actuator is transmitted via the power transmission system from the actuator to the nozzle needle changes depending on the fuel pressure. In view of the above, an appropriate adjustment amount corresponding to each fuel pressure can be set.

  According to a tenth aspect of the present invention, in the ninth aspect, the adjustment amount is set according to the fuel injection mode at each of several values of the fuel pressure before the fuel injection valve is mounted on an engine system. A process for creating an arithmetic expression for determining the relationship between the fuel pressure and the adjustment amount based on the measurement, and after the fuel injection valve is mounted in the system, the adjustment amount is calculated by substituting the fuel pressure for each calculation expression. And a setting process.

  In the above method, in view of the fact that the relationship between the fuel pressure and the adjustment amount can be accurately approximated by an arithmetic expression, the above arithmetic expression is used when setting the adjustment amount after the fuel injector is mounted on the engine system. The amount of data stored in the control system can be reduced.

  According to an eleventh aspect of the present invention, in any one of the first to tenth aspects, the fuel injection mode is measured before the fuel injection valve is actually mounted on the engine system, thereby causing the solid difference. It is characterized by acquiring unique information.

  According to the above method, by performing the measurement before the fuel injection valve is actually mounted on the engine system, the fuel injection rate by the fuel injection valve can be improved from the initial operation of the internal combustion engine.

  According to a twelfth aspect of the invention, in any one of the first to eleventh aspects, after the fuel injection valve is mounted on the engine system, the rotational state of the output shaft of the internal combustion engine is feedback controlled to the target rotational state. And acquiring the specific information by processing the operation of the actuator and detecting the difference between the operation amount serving as a reference for setting the target rotation state and the operation amount in the feedback control. It is characterized by that.

  In the above method, after the fuel injection valve is mounted in the engine system, the rotation state is feedback-controlled to the target rotation state. The amount of operation of the actuator in this feedback control is influenced by the individual difference of fuel injection valves and changes with time. That is, for example, when the actual lift amount becomes smaller than the operation for increasing the lift amount due to the difference in solids or changes over time, the degree to which the operation to increase the lift amount by feedback control is performed is larger. Become. Therefore, the difference between the reference operation amount for achieving the target rotational state and the operation amount in the feedback control is a solid difference in the injection characteristic of the fuel injection valve with respect to the reference injection characteristic of the fuel injection valve. And variations due to changes over time are quantified.

  According to a thirteenth aspect of the present invention, in any one of the first to twelfth aspects, the actuator is a piezo actuator.

  In the above method, by using a piezo actuator, the extension amount of the actuator can be controlled in accordance with the drive control energy input to the actuator.

  According to a fourteenth aspect of the present invention, in the thirteenth aspect, the operation amount is drive control energy of the piezoelectric actuator.

  In the above method, the extension amount of the piezoelectric actuator can be controlled by using the drive control energy. For this reason, in the fuel injection valve in which the lift amount of the nozzle needle is determined according to the extension amount of the actuator, the lift amount of the nozzle needle can be easily controlled.

  As the drive control energy, for example, the voltage of the piezo actuator, the time integral value of the current, the time integral value of the product of the current and voltage, and the like are desirable. Moreover, it is good also as a function which uses these as a parameter.

  According to a fifteenth aspect of the present invention, in the thirteenth or fourteenth aspect, the adjustment of the operation amount is performed as a correction with respect to a reference operation amount, and the increase control of the lift amount is a charge profile for the piezo actuator. Is performed while making the reference operation amount and the corrected operation amount the same.

  In the above method, the charge profile is the same between the corrected and non-corrected operation amounts, and between the corrected ones. For this reason, the increased portion of the lift amount in the lift waveform (the increased portion of the injection rate in the injection rate waveform) is the same with or without the corrected operation amount, and between the corrected ones. be able to.

  According to a sixteenth aspect of the present invention, in any one of the thirteenth to fifteenth aspects, the adjustment of the operation amount is performed as a correction for a reference operation amount, and the reduction control of the lift amount is performed by the piezoelectric actuator. The discharge profile with respect to is set to be the same between the reference operation amount and the corrected operation amount.

  In the above method, the discharge profile is the same between the corrected amount and the corrected amount, and between the corrected amounts. For this reason, the lift amount decrease portion in the lift waveform (the injection rate decrease portion in the injection rate waveform) is the same with or without the corrected operation amount, and between the corrected ones. be able to.

  According to a seventeenth aspect of the invention, there is provided storage means for storing unique information resulting from individual differences of the fuel injection valve regarding the relationship of the displacement of the lift amount of the nozzle needle with respect to the operation amount of the actuator.

  In the above method, since the storage means for storing the unique information is provided, the operation mode of the fuel injection valve by the control system of the engine system can be suitably adjusted when the fuel injection valve is mounted on the engine system.

  The information stored in the storage means may be used in the fuel injection control with the injection rate waveform described in claim 2 or 3, and is for adjustment in claim 4. Also good. Moreover, it is good also as including the information regarding the adjustment amount of the said Claims 5-10, and you may include the information of Claim 11. Furthermore, the fuel injection valve according to claim 17 may include the actuator according to claim 13.

  In the invention according to claim 18, the storage means for storing the unique information due to the individual difference regarding the relationship of the displacement of the lift amount of the nozzle needle with respect to the operation amount of the actuator, and the information stored in the storage means And setting means for setting an operation amount of the actuator based on the setting value.

  According to the above configuration, by setting the operation amount using unique information, it is possible to suppress variations in fuel injection modes that occur when a common operation amount is set for the same type of fuel injection valve without using this information. can do. For this reason, the actual injection rate waveform can be approximated to the target injection rate waveform regardless of the individual difference.

  The operation amount in claim 18 may be set so that the actual injection rate waveform becomes the target injection rate waveform shown in claim 2 or 3. Further, the setting of the operation amount may be performed as the adjustment of the operation amount described in the means 4, or may be performed using the adjustment amount described in claims 5 to 10. Further, the information about the individual difference may be as shown in claim 11. Further, the fuel injection valve according to claim 18 may include the actuator according to claim 13.

  According to a nineteenth aspect of the present invention, there is provided control means for feedback-controlling the rotation state of the output shaft of the internal combustion engine on which the fuel injection valve is mounted to a target rotation state by operating the actuator, and the target rotation state. A storage means for storing a reference value of the operation amount of the actuator for control, and an operation amount of the actuator when the actual rotation state is set to the target rotation state by the control means and the storage means. Acquisition means for acquiring information specific to the fuel injection valve regarding the relationship of the displacement of the nozzle needle with respect to the operation amount of the actuator based on the difference from the operated operation amount, and information acquired by the acquisition means And a correction means for correcting the operation amount of the actuator.

  In the above configuration, the rotational state of the internal combustion engine is feedback-controlled to the target rotational state. The amount of operation of the actuator in this feedback control is influenced by the individual difference of fuel injection valves and changes with time. That is, for example, when the actual lift amount becomes smaller than the operation for increasing the lift amount due to the difference in solids or changes over time, the degree to which the operation to increase the lift amount by feedback control is performed is larger. Become. Therefore, the difference between the reference operation amount for achieving the target rotational state and the operation amount in the feedback control is a solid difference in the injection characteristic of the fuel injection valve with respect to the reference injection characteristic of the fuel injection valve. And variations due to changes over time are quantified. For this reason, in the said structure, based on the information acquired based on the said difference, the operation amount can be correct | amended so that the change of the lift amount by a time-dependent change or a solid difference may be removed.

(First embodiment)
Hereinafter, a first embodiment in which a fuel injection control method, a fuel injection valve, and a fuel injection control device according to the present invention are applied to fuel injection control using a fuel injection valve mounted on a diesel engine will be described with reference to the drawings. To do.

  FIG. 1 shows an overall configuration of an engine system including the diesel engine. As shown in the drawing, the fuel pumped up from the fuel tank 2 is pressurized by the high-pressure fuel pump 4 and supplied to the common rail 6 in a high-pressure state. The common rail 6 stores the fuel supplied from the high-pressure fuel pump 4 in a high-pressure state and supplies the fuel to the fuel injection valve 10 via the high-pressure fuel passage 8. The fuel injection valve 10 is also connected to a low-pressure fuel passage 12 so that fuel can be returned to the fuel tank 2 via the low-pressure fuel passage 12.

  The electronic control unit (ECU 20) includes a microcomputer, a memory, and the like, and controls the output of the internal combustion engine. In this control, the ECU 20 uses the detection results of various sensors such as the detection result of the fuel pressure sensor 14 that detects the fuel pressure in the common rail 6 and the detection result of the crank angle sensor 16 that detects the rotation angle of the crankshaft of the internal combustion engine. Capture and refer to these detection results.

  FIG. 2 shows the configuration of the fuel injection valve 10.

  An injection port 32 that communicates the inside of the body 30 and the outside of the fuel injection valve 10 is formed at the tip of the body 30 of the fuel injection valve 10. In the body 30, a nozzle needle 34, a needle stopper 36, and a balance piston 38 are sequentially connected from the distal end side, and are housed so as to be displaceable in the axial direction along the inner wall of the body 30. High-pressure fuel is supplied from the high-pressure fuel passage 8 between the nozzle needle 34 and the inner wall of the body 30 and the back side of the balance piston 38.

  A spring 40 is provided on the rear surface side of the body 30 in the needle stopper 36, whereby the needle stopper 36 is pushed toward the distal end side of the body 30. Further, a back pressure chamber 41 formed by the rear surface of the body 30 and the inner wall of the body 30 in the needle stopper 36 is in communication with the low pressure fuel passage 12, and fuel is supplied from the low pressure fuel passage 12. Is done.

  On the other hand, in the needle stopper 36, the surface side on the distal end side of the body 30 forms a first oil tight chamber 42 together with the inner wall of the body 30. The first oil-tight chamber 42 is connected to a second oil-tight chamber 46 located behind the body 30 with respect to the balance piston 38 via the transmission passage 44. The first oil-tight chamber 42, the transmission passage 44, and the second oil-tight chamber 46 are filled with fuel as a medium for transmitting power.

  The second oil-tight chamber 46 is a space formed between the surface of the piezo piston 48 on the front end side of the body 30 and the inner wall of the body 30. The piezo piston 48 includes a check valve 50 inside thereof, so that fuel can be supplied from the low pressure fuel passage 12 to the second oil tight chamber 46. The piezo piston 48 is connected to the piezo actuator 52 at the rear thereof. The rear part of the piezo actuator 52 is connected and fixed to the body 30.

  In such a configuration, when energization of the piezo actuator 52 is started, the piezo piston 48 is displaced in the distal direction of the body 30 as the piezo actuator 52 extends. As a result, the fuel pressure in the second oil-tight chamber 46, the transmission passage 44, and the first oil-tight chamber 42 increases. The force that the high pressure fuel pushes the nozzle needle 34 and the force that the fuel in the first oil-tight chamber 42 pushes the needle stopper 36 are the force that the spring 40 and the low pressure fuel push the needle stopper 36 and the high pressure fuel is the balance piston 38. When the force to push the back surface is overcome, the nozzle needle 34 is displaced rearward of the body 30 and the fuel injection valve 10 is opened. Thereby, the fuel inside the body 30 is injected outside through the injection port 32.

  On the other hand, when the piezo actuator 52 is discharged after being energized, the piezo piston 48 is displaced rearward of the body 30 as the piezo actuator 52 contracts, so that the first oil-tight chamber 42, the transmission passage 44, and the second oil-tight chamber 46. The fuel pressure inside decreases. Thereby, the force that the spring 40 and the low-pressure fuel push the needle stopper 36 and the force that the high-pressure fuel pushes the back surface of the balance piston 38, the force that the high-pressure fuel pushes the nozzle needle 34, and the fuel in the first oil-tight chamber 42 become the needle. When the force to push the stopper 36 is overcome, the nozzle needle 34 is displaced toward the distal end side of the body 30 and the fuel injection valve 10 is closed. Thereby, fuel injection is complete | finished.

  In the fuel injection valve 10, the lift amount, which is the displacement amount of the nozzle needle 34 to the rear of the body 30, changes according to the displacement amount of the piezo actuator 52. For this reason, the lift amount can be arbitrarily controlled between the lift amount corresponding to the closing of the fuel injection valve 10 and the full lift amount which is the maximum lift amount. That is, for example, when operating the voltage by energizing the piezo actuator 52, if a certain voltage period is provided, the nozzle needle 34 is stagnated with an intermediate lift amount. For this reason, after that energization control is resumed and the voltage is raised, lift control having a two-stage lift amount becomes possible. Thus, since the lift amount can be freely controlled by using the fuel injection valve 10, not only the fuel injection amount but also the fuel injection rate waveform in one fuel injection can be freely controlled. It becomes possible. Incidentally, the fuel injection rate here means the amount of fuel per unit time injected from the fuel injection valve 10.

  By the way, as for the said fuel injection valve 10, the thing of the same structure is actually manufactured in large quantities, and each will be mounted in a diesel engine. At this time, the dimensional variation allowed for each component of the fuel injection valve 10, the characteristic variation of the piezo actuator 52, and the like occur, and the fuel injection valve 10 has a solid difference. Even if the piezo actuator 52 is operated in the same operation mode due to the individual difference, the displacement mode of the lift amount of the nozzle needle 34 and the waveform of the fuel injection rate are different depending on the individual difference of the individual fuel injection valves 10. The resulting variation occurs.

  FIG. 3 shows an example of the variation in the lift amount of the nozzle needle 34 and the variation in the injection rate due to the individual difference of the fuel injection valve 10. Here, FIG. 3A shows the transition of the voltage (operation voltage) applied to the piezo actuator 52, FIG. 3B shows the transition of the lift amount of the nozzle needle 34, and FIG. 3C shows the injection rate. Shows the transition.

  In the example of FIG. 3, by operating the operation voltage applied to the piezo actuator 52 in two steps, the lift amount of the nozzle needle 34 and the fuel injection rate injected from the fuel injection valve 10 are controlled in two steps. However, even if the operation voltage is the same, the lift amount of the nozzle needle 34 and the injection rate of the fuel injected from the fuel injection valve 10 vary due to individual differences of the fuel injection valves 10.

  Compensation for variations in fuel injection characteristics due to individual differences cannot be performed by adjusting the period during which voltage is applied to the piezoelectric actuator 52. That is, in this case, the variation in the fuel injection amount (the variation in the time integral value of each fuel injection rate in FIG. 3C) can be compensated, but the variation in the change in the lift amount is compensated for this. It is not possible. For this reason, although the fuel injection rate can be controlled by the fuel injection valve 10, it is not possible to compensate for variations in the fuel injection rate due to individual differences of the fuel injection valves 10.

  Therefore, in this embodiment, the above-described variation is compensated by adjusting each operation voltage corresponding to each lift amount (lift stage) in which the lift amount is set in two stages.

  Specifically, as shown in FIG. 4, the operation voltage is corrected by multiplying each of the two stages of operation voltages V1 and V2 by the same adjustment coefficient k. FIG. 5 shows an example of correction using this adjustment coefficient. Here, FIG. 5A shows the transition of the operating voltage of the piezo actuator 52, FIG. 5B shows the transition of the lift amount of the piezo piston 48, and FIG. 5C shows the lift amount of the nozzle needle 34. FIG. 5 (d) shows the transition of the injection rate.

  In FIG. 5B to FIG. 5D, the solid line indicates an average characteristic when a plurality of fuel injection valves 10 are manufactured. On the other hand, the broken lines in FIGS. 5B to 5D indicate the characteristics of the individual in which the lift amount and the fuel injection rate are more varied than the average characteristics. The operation voltage indicated by the alternate long and short dash line in FIG. 5A is obtained by multiplying the operation voltage by an adjustment coefficient k (<1) so that the individual characteristic having the characteristic indicated by the broken line is the average characteristic. This shows the corrected operation voltage. As a result, as shown by the alternate long and short dash line in FIGS. 5B to 5D, the lift amount and the injection rate of the individual are approximated to the average one shown by the solid line.

  Here, in the present embodiment, a procedure of processing for compensating for variations in individual differences of the fuel injection valves 10 and reflecting them in the control mode by the ECU 20 shown in FIG. 1 will be described. FIG. 6 shows the procedure of this process.

  In this series of processes, first, in step S10, a plurality of measurement points are determined by the injection period of the fuel injected from the fuel injection valve 10 and the pressure (fuel pressure) of the fuel supplied to the fuel injection valve 10. The injection characteristic of the fuel injection valve 10 is measured for each measurement point. FIG. 7 shows an example of setting the measurement points. In FIG. 7, the horizontal axis represents the operation time (drive pulse width) by the operation voltage, and the vertical axis represents the injection amount. The curve in FIG. 7 shows that the relationship between the operation time and the injection amount changes depending on the fuel pressure. In FIG. 7, the measurement points are indicated by circles. Here, a plurality of measurement points are determined by two-dimensional parameters of the injection period and the fuel pressure.

  A plurality of measurement points are provided in the above manner for the following reason. The amount of lift of the nozzle needle 34 is a balance between the fuel pressure in the first oil tight chamber 42, the pressure of the fuel charged between the nozzle needle 34 and the body 30, the pressure of the fuel exerted on the back surface of the balance piston 38, and the like. It depends on. The balance of these forces varies depending on the fuel pressure supplied to the fuel injection valve 10 and the fuel injection period. For this reason, in this embodiment, a plurality of measurement points are determined by the fuel injection period and the fuel pressure, and the fuel injection characteristics are measured respectively.

  Here, the measurement of the fuel injection characteristic may be performed, for example, by measuring the fuel injection rate in real time throughout the fuel injection period. Alternatively, the measurement may be performed by measuring the fuel injection amount injected during the fuel injection period.

  In subsequent step S12, an adjustment coefficient of the operation voltage of the piezo actuator 52 is determined for each measurement point based on the measurement result in step S10. Here, for example, (b) based on the average characteristics of the plurality of fuel injection valves 10 and the like, first, the reference operating voltage is determined. The adjustment may be performed by, for example, determining the adjustment coefficient by gradually calculating the operation voltage required to obtain the injection characteristic) with the reference operation voltage. Here, the operation voltage required to obtain a desired lift characteristic (injection characteristic) may be determined by actually performing fuel injection at several operation voltages.

  When the adjustment coefficient is thus determined, the adjustment coefficient is stored in the QR code of the fuel injection valve 10 in step S14. Here, the QR code is a kind of two-dimensional code having the overview shown in FIG. 8 and having information in the vertical direction and the horizontal direction.

  In the subsequent step S16, when the fuel injection valve 10 is mounted on the engine system, the adjustment coefficient is taken from the QR code and stored in the ECU 20. Specifically, as shown in FIG. 8, the QR code provided in the fuel injection valve 10 is read by the QR code scanner 60 and once taken into the personal computer 62. The personal computer 62 converts the captured QR code into data that can be processed by the ECU 20 and stores the data in the ECU 20.

  The subsequent steps S18 and S20 are performed by the ECU 20. That is, first, in step S18, in each fuel injection control, the corresponding adjustment coefficient is determined based on the fuel injection period determined by the operation amount of the accelerator pedal and the fuel pressure in the common rail 6 determined by the operating state of the diesel engine. Select. In the subsequent step S20, the operation voltage of the piezo actuator 52 is corrected by multiplying the operation voltage of the reference piezo actuator 52 provided in the ECU 20 by the selected adjustment coefficient. By operating the piezo actuator 52 based on the corrected operation voltage in this way, it is possible to compensate for variations in the injection rate due to individual differences among the fuel injection valves 10. By the way, when at least one of the fuel injection period and the fuel pressure is different from the measurement points used when determining each adjustment coefficient stored in the ECU 20, an interpolation calculation using adjustment coefficients at some adjacent measurement points is performed. The adjustment coefficient corresponding to the fuel injection period and the fuel pressure may be determined.

  By the way, by operating the piezo actuator 52 based on the operation voltage corrected by the adjustment coefficient, it is possible to compensate for variations in the lift amount at each lift stage of the nozzle needle 34. In this embodiment, the piezo actuator 52 is operated in the ECU 20 so as to suppress the variation in the variation of the lift amount when shifting to each lift stage. This operation is performed by making the charging mode (charging profile) and discharging mode (discharging profile) of the piezo actuator 52 the same for the uncorrected and the corrected ones. This will be described below.

  FIG. 9 shows the injection rate waveforms of the uncorrected and the corrected one when the change speed of the operation voltage of the piezoelectric actuator 52 is constant. Specifically, FIG. 9A shows the transition of the operating voltage of the piezo actuator 52, FIG. 9B shows the transition of the lift amount of the piezo piston 48, and FIG. 9C shows the lift amount of the nozzle needle 34. FIG. 9 (d) shows the transition of the fuel injection rate. Incidentally, in FIG. 9, the constant charging speed means that the increasing speed when the operating voltage is increased is the same regardless of whether correction is performed or not, and the constant discharging speed is a decrease when the operating voltage is decreased. It means that the speed is the same regardless of whether correction is performed.

  In FIG. 9, characteristics that serve as a reference for correction, such as average characteristics of the plurality of fuel injection valves 10, are indicated by a one-dot chain line. On the other hand, the solid line shown in FIG. 9 shows the characteristic after correction when the piezo piston 48 and the nozzle needle 34 vary toward the side where the lift amount becomes smaller than the reference. As shown in FIG. 9A, the operation voltage at the lift stage (here, one stage is assumed and corresponds to the maximum value of the lift amount) is corrected by the adjustment coefficient, and the change speed of the operation voltage is corrected. By making the same for the non-standard and the corrected one, the injection rate waveform can be suitably approximated as shown in FIG.

  Incidentally, in FIGS. 9B and 9C, the lift amount of the piezo piston 48 and the lift amount of the nozzle needle 34 are greatly different from each other between the reference and the corrected ones. It has become. However, this is in a region corresponding to a large lift amount that does not contribute to the change in the injection rate. That is, the fuel injection rate has an upper limit of the maximum injection rate determined by the opening area of the injection port 32 of the fuel injection valve 10, and therefore when the lift amount of the nozzle needle 34 increases to some extent, the lift amount contributes to the change in the injection rate. No longer. 9B and 9C, the lift amount in the lift region where the change in the lift amount contributes to the change in the injection rate is substantially the same between the reference and the corrected ones. Show.

  On the other hand, in FIG. 10, the time required to increase the operating voltage of the piezo actuator 52 from “0V” to a voltage corresponding to a predetermined lift stage, or the voltage corresponding to the predetermined lift stage is decreased to “0V”. The case where the time required for the correction is the same for the reference without correction and the correction is shown. Specifically, FIG. 10A shows the transition of the operating voltage of the piezo actuator 52, FIG. 10B shows the transition of the lift amount of the piezo piston 48, and FIG. 10C shows the lift amount of the nozzle needle 34. FIG. 10 (d) shows the transition of the fuel injection rate.

  In FIG. 10, characteristics serving as a reference for correction, such as average characteristics of the plurality of fuel injection valves 10, are indicated by a one-dot chain line. On the other hand, the solid line in FIG. 10 shows the characteristic after correction when the lift amount of the piezo piston 48 and the nozzle needle 34 varies with respect to the reference. Here, as shown in FIG. 10 (a), the operation voltage at the lift stage (here, one stage is assumed and corresponds to the maximum value of the lift amount) is corrected by the adjustment coefficient, and the charging time and discharging time are adjusted. Each characteristic in the case where the reference standard without correction and the standard correction are the same is shown by solid lines in FIGS. 10 (b) to 10 (d).

  As shown in the figure, at the time of charging, although the corrected operating voltage is higher than the reference, in order to perform an operation that makes the charging time constant, the reference speed without the correction of the operating voltage is not corrected. It will be larger than the ones. For this reason, the injection start time is also earlier than the reference one.

  On the other hand, at the time of discharge, although there is no great difference in the injection end timing, the rate of decrease in the operating voltage is larger than that without correction, so the rate of change in the lift amount of the piezo piston 48 and the nozzle needle 34 is increased. If it becomes large, there is a possibility that an increase in seating sound at the time of valve closing, bounce at the time of valve closing, and the like may occur.

  For the above reasons, in this embodiment, the charging rate and the discharging rate are set to be substantially the same between the reference value without correction and the correction rate. FIG. 11 shows a configuration of a drive circuit of the piezo actuator 52 in the present embodiment.

  As shown in the drawing, the electric power supplied from the battery B to the ECU 20 is first supplied to a DC / DC converter 21 which is a booster circuit. The DC / DC converter 21 boosts the voltage of the battery B (for example, “12 V”) to a high voltage (for example, “200 to 300 V”) for charging the piezo actuator 52.

  The boosted voltage of the DC / DC converter 21 is applied to the capacitor 22. One terminal of the capacitor 22 is connected to the DC / DC converter 21 side, and the other terminal is grounded. When the boosted voltage of the DC / DC converter 21 is applied to the capacitor 22, the capacitor 22 stores electric charge to be supplied to the piezo actuator 52. Incidentally, it is desirable that the capacitor 22 has a capacity (for example, about “several hundred μF”) such that the voltage hardly changes by a single charging process to the piezo actuator 52.

  The terminal side of the capacitor 22 that becomes a high potential, that is, the DC / DC converter 21 side is connected to the terminal side that becomes the high potential of the piezo actuator 52 via a series connection body of the charging switch 23 and the charging / discharging coil 24. It is connected. The terminal side of the piezoelectric actuator 52 that is at a low potential is grounded.

  One terminal of a discharge switch 25 is connected between the charge switch 23 and the charge / discharge coil 24, and the other terminal of the discharge switch 25 is grounded.

  A diode 26 is connected in parallel to the discharge switch 25. The cathode of the diode 26 is connected between the capacitor 22 and the charge / discharge coil 24, and the anode thereof is connected to the ground side. The diode 26, together with the capacitor 22, the charge switch 23, and the charge / discharge coil 24, constitutes a chopper circuit that charges the piezo actuator 52, and functions as a freewheeling diode.

  On the other hand, a diode 27 is connected to the charging switch 23 in parallel. The diode 27 has a cathode side connected to the capacitor 22 side and an anode side connected to the discharge switch 25 side. The diode 27, together with the capacitor 22, the charge / discharge coil 24, and the discharge switch 25, constitutes a chopper circuit that discharges the electric charge of the piezoelectric actuator 52, and functions as a freewheeling diode.

  The drive circuit having the above configuration is driven by the microcomputer 28. Specifically, the microcomputer 28 operates the charge switch 23 and the discharge switch 25 based on the detection values of various sensors that detect the operating state of the diesel engine. Each of these operations is performed in the manner shown in FIG.

  12A shows the transition of the operation mode of the charge switch 23, FIG. 12B shows the transition of the operation mode of the discharge switch 25, and FIG. 12C shows the current flowing through the piezo actuator 52 (operation FIG. 12D shows the transition of the operating voltage of the piezo actuator 52. FIG.

  As shown in the figure, the piezo actuator 52 is charged while increasing or decreasing the operating current by chopper control by turning on / off the charging switch 34. Specifically, when the charging switch 23 is turned on, a closed loop circuit including the capacitor 22, the charging switch 23, the charging / discharging coil 24, and the piezo actuator 52 is formed. Thereby, the electric charge of the capacitor 22 is charged in the piezo actuator 52. At this time, the amount of current flowing through the piezoelectric actuator 52 increases. On the other hand, after the charging switch 23 is turned on, the charging switch 23 is turned off, whereby a closed loop circuit including the charging / discharging coil 24, the piezoelectric actuator 52, and the diode 26 is formed. Thereby, the flywheel energy of the charge / discharge coil 24 is charged in the piezo actuator 52. At this time, the amount of current flowing through the piezo actuator 52 decreases.

  By performing the step-down chopper control in which the charging switch 23 is operated in the above-described manner, the piezo actuator 52 is charged, and the potential on the terminal side that becomes the high potential of the piezo actuator 52 rises.

  On the other hand, the piezo actuator 52 is discharged while increasing / decreasing the operation current by the chopper control by turning on / off the discharge switch 25. Specifically, when the discharge switch 25 is turned on, a closed loop circuit is formed by the discharge switch 25, the charge / discharge coil 24, and the piezo actuator 52. As a result, the piezo actuator 52 is discharged. At this time, the amount of current flowing through the piezoelectric actuator 52 increases. Further, after the discharge switch 25 is turned on, the discharge switch 25 is turned off, whereby a closed loop circuit is formed by the capacitor 22, the diode 27, the charge / discharge coil 24, and the piezo actuator 52. Thereby, the flywheel energy of the charge / discharge coil 24 is recovered by the capacitor 22.

  By performing step-up chopper control in which the discharge switch 25 is operated in the above-described manner, the piezo actuator 52 is discharged, and the potential on the terminal side that becomes the high potential of the piezo actuator 52 decreases.

  In the charge control and discharge control, particularly in the present embodiment, the charge switch 23 (discharge switch 25) is turned off every time the charge current (discharge current) reaches a predetermined upper limit value, and the charge current (discharge current) is zero. Every time the charging switch 23 (discharging switch 25) is turned on, an operation is performed. By performing chopper control in this manner in the ECU 20, the average charging speed and the average discharging speed can be made substantially the same between the reference without correction of the operation voltage and the corrected one. For this reason, it is possible to make the charge profile and the discharge profile substantially the same for both the reference without correction of the operation voltage and the corrected one, and thus the injection rate waveform can be made substantially equal between them.

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

  (1) Based on the fuel injection mode measured when the piezo actuator 52 is operated, the unique information resulting from the individual difference of the fuel injection valve 10 regarding the relationship of the displacement of the nozzle needle 34 with respect to the operating voltage is acquired, and the acquisition Based on the obtained information, the operation voltage was adjusted to approximate the actual injection rate waveform by the fuel injection valve 10 to the target injection rate waveform. In this way, by using the information on the unique relationship, an operation for suppressing variations in the fuel injection mode that occurs when a common operation voltage is set with the fuel injection valve of the same model without using the unique relationship. The voltage can be adjusted.

  (2) The operation voltage was adjusted for each operation voltage corresponding to each of the multi-stage lift stages. Thereby, the dispersion | variation in the injection rate corresponding to each multistage lift stage can be suppressed. For this reason, the actual injection rate waveform can be suitably approximated to the target injection rate waveform.

  (3) The adjustment coefficient that is the same as the value for each lift amount with respect to the operation voltage serving as a reference for realizing the target injection rate waveform for the adjustment for each operation voltage corresponding to each of the multi-stage lift stages. It was done by multiplying. Thereby, the dispersion | variation in the actual lift amount in each lift stage can be suppressed simply and suitably.

  (4) The adjustment coefficient was set separately for each of the plurality of fuel injection periods. Thereby, the balance of force when the power from the piezoelectric actuator 52 is transmitted to the nozzle needle 34 via the power transmission system from the piezoelectric actuator 52 to the nozzle needle 34 changes depending on the fuel injection period. In view of this, it is possible to set an appropriate adjustment coefficient corresponding to each injection period.

  (5) The adjustment coefficient was set for each fuel pressure in the common rail 6. As a result, the balance of force when the power from the piezo actuator 52 is transmitted to the nozzle needle 34 via the power transmission system from the piezo actuator 52 to the nozzle needle 34 changes depending on the fuel pressure. In view of this, it is possible to set an appropriate adjustment coefficient corresponding to each fuel pressure.

  (6) By measuring the fuel injection mode before the fuel injection valve 10 is actually mounted on the engine system, the fuel injection rate by the fuel injection valve 10 can be improved from the initial operation of the diesel engine. .

  (7) The increase control of the lift amount is performed so that the charge profile for the piezo actuator 52 is the same between the reference operation voltage and the corrected one. As a result, the lift amount increasing portion in the lift waveform (the injection rate increasing portion in the injection rate waveform) is the same with or without the corrected operation voltage, and between the corrected ones. be able to.

  (8) The reduction control of the lift amount is performed so that the discharge profile for the piezo actuator 52 is the same between the reference operation voltage and the corrected one. Thereby, the reduced amount of the lift amount in the lift waveform (the reduced portion of the injection rate in the injection rate waveform) is made the same as the one that does not correct the operation voltage and between the corrected ones. be able to.

  (9) The fuel injection valve 10 is provided with a QR code that stores the adjustment coefficient. Thereby, matching with the fuel injection valve 10 and ECU20 becomes easy. For this reason, since it is not necessary to manufacture them while associating them in advance, the complexity at the time of manufacturing can be reduced.

(Second Embodiment)
Hereinafter, the second embodiment will be described with reference to the drawings with a focus on differences from the first embodiment.

  In the first embodiment, an adjustment coefficient is determined and stored in the QR code for each measurement point determined by the fuel injection period and the fuel pressure, and the operation voltage is corrected by the ECU 20 based on the stored adjustment coefficient. On the other hand, in the present embodiment, a primary expression that defines the relationship between the fuel injection amount (corresponding to the injection period), the fuel pressure, and the adjustment coefficient is created based on the processing in steps S10 to S12 in FIG. The coefficients (including the intercept) of the formula are stored in the QR code. Specifically, the relationship between the fuel injection amount Q, the fuel pressure P, and the adjustment coefficient K is expressed by “K = α × P + β × Q + γ”.

  FIG. 13 shows an example of the correlation coefficient between the adjustment coefficient actually measured and determined, and the adjustment coefficient calculated by the linear expression. In FIG. 13, “α = 3.34E-4, β = 1.84E-3, γ = 0.008”, the unit of fuel pressure is “MPa”, and the unit of injection amount is “mm3 / st”. did. As shown in the drawing, the correlation coefficient is “0.9752”, and the adjustment coefficient actually measured and determined has a strong correlation with the adjustment coefficient determined by the linear expression.

  For this reason, the ECU 20 can calculate an appropriate adjustment coefficient by substituting the injection amount and the fuel pressure each time into the above-described linear expression.

  Note that when using the primary expression, the number of lift stages may be changed according to the fuel injection amount or the like. Incidentally, FIG. 13 shows the measurement result in the case where the fuel injection control by the first lift stage or the fuel injection control by the second lift stage is selected according to the fuel injection amount and the fuel pressure. It has become.

  According to this embodiment described above, the following effects can be obtained in addition to the effects (1) to (9) of the first embodiment.

  (10) Before the fuel injection valve 10 is mounted on the engine system, a linear expression is created that defines the relationship between the fuel injection amount and the adjustment coefficient based on the measurement of the fuel injection mode at each of the plurality of values of the fuel injection amount. After the fuel injection valve 10 was installed in the system, the adjustment coefficient was set by substituting the fuel injection amount for each linear equation. Thereby, the memory | storage data amount memorize | stored in ECU20 can be reduced.

  (11) Before the fuel injection valve 10 is mounted on the engine system, a primary expression for defining the relationship between the fuel pressure and the adjustment coefficient is created based on the measurement of the fuel injection mode at each of a plurality of values of the fuel pressure, and the fuel injection valve After 10 was installed in the system, the adjustment coefficient was set by substituting the fuel pressure for each linear equation. Thereby, the memory | storage data amount memorize | stored in ECU20 can be reduced.

(Third embodiment)
Hereinafter, the third embodiment will be described with reference to the drawings with a focus on differences from the first embodiment.

  In the first embodiment, the operation voltage corresponding to each lift stage is corrected with the same adjustment coefficient. On the other hand, in this embodiment, as shown in FIG. 14, the operation voltage is corrected by multiplying adjustment coefficients k1 and k2 that are independently determined for each operation voltage corresponding to each lift stage. For this reason, even when the relationship between the variation of the actual lift amount (injection rate) with respect to the reference and the operation voltage has nonlinearity, the variation of each lift stage can be suitably suppressed. Incidentally, in the present embodiment, the measurement of the injection characteristic in step S10 of FIG. 6 is preferably performed as measurement of the fuel injection rate in real time or as measurement of the fuel injection rate at each lift stage.

  According to this embodiment described above, in addition to the effects (1), (2), (4) to (9) of the first embodiment, the following effects can be obtained. .

  (12) With respect to the operation voltage serving as a reference for realizing the target injection rate waveform, the adjustment coefficient is corrected by multiplying the value for each lift amount by an independently determined adjustment coefficient. Thereby, the dispersion | variation in the actual lift amount in each lift stage can be suppressed more suitably.

(Fourth embodiment)
Hereinafter, the fourth embodiment will be described with reference to the drawings with a focus on differences from the second embodiment.

  While using the fuel injection valve 10, for example, the spring 40 passes, the spring constant changes, or the frictional force between the relatively displaced parts such as the friction between the nozzle needle 34 and the inner wall of the body 30. May change. Such a change with time cannot be dealt with by an adjustment coefficient based on unique information caused by individual differences of the fuel injection valves 10 as in the above embodiment. Therefore, in the present embodiment, the injection characteristic of the fuel injection valve 10 due to change over time is detected during idle rotation speed control of the diesel engine, and an adjustment coefficient that compensates for variations in injection characteristic due to change over time is obtained. This will be described below with reference to FIG.

  FIG. 15 shows a procedure of processing related to calculation of an adjustment coefficient for compensating for the change with time. This process is a process repeatedly executed by the ECU 20 at, for example, a predetermined cycle.

  In this series of processes, first, in step S30, it is determined whether or not the diesel engine controlled by the ECU 20 is executing the idle rotation speed control. Here, the idle rotation speed control is a feedback control to the target rotation speed of the crankshaft of the diesel engine by manipulating the fuel injection amount during idling.

  If it is determined in step S30 that the engine is idling, it is determined in step S32 whether or not the actual rotational speed matches the target rotational speed by the feedback control. When it is determined that the actual rotational speed has reached the target rotational speed, in step S34, the injection characteristics of the fuel injection valve 10 (the lift characteristics of the nozzle needle 34, the fuel injection characteristics) are set to the desired injection during idling. An adjustment coefficient kact as a characteristic is calculated. This adjustment coefficient is set as a value when the operation voltage when the actual rotation speed coincides with the target rotation speed in step S32 is gradually subtracted by the operation voltage serving as a reference during idling. Here, the change in the injection characteristic of the fuel injection valve 10 due to the change over time is reflected in the operation voltage when the actual rotation speed matches the target rotation speed.

  For example, when the lift amount is small with respect to the operation voltage, when the piezo actuator 52 is operated with the reference operation voltage, the rotational speed of the diesel engine becomes smaller than the target rotational speed. Further, for example, when the lift amount becomes larger than the operation voltage, when the piezo actuator 52 is operated with the reference operation voltage, the rotational speed of the diesel engine becomes larger than the target rotational speed. When the operation voltage is adjusted to control the actual rotation speed to the target rotation speed by the idle rotation speed control, the operation voltage is a value for compensating for the change in the injection characteristics due to the change with time. It becomes.

  For this reason, the adjustment coefficient at the time of idling can be determined by dividing the operation voltage at this time by the reference operation voltage.

  When the process of step S34 is completed, an adjustment coefficient for the fuel pressure P and the fuel injection amount Q is calculated in step S36. Here, as shown in the second embodiment, the adjustment coefficient is calculated based on the adjustment coefficient being calculated by a linear expression of the fuel pressure P and the injection amount Q. Specifically, the linear expression is corrected by multiplying the linear expression determined in the second embodiment by “kact / kref”. In other words, these coefficients are corrected by multiplying each coefficient (and intercept) α, β, γ of the linear expression by “kact / kref”. Incidentally, “kref” is defined as “kref = α × P0 + β × Q0 + γ”, where “P0” is the fuel pressure during idling and “Q0” is the injection amount serving as a reference during idling.

  Thus, according to step S36, the primary expression can be easily corrected according to the change with time.

  If it is determined in step S30 that the engine is not idling, if it is determined in step S32 that the actual rotational speed does not match the target rotational speed, or if the process in step S36 is completed, this process is performed. Exit once.

  According to the present embodiment described above, the following effects can be obtained in addition to the effects of the second embodiment.

  (13) Based on the difference between the operation voltage used as a reference for setting the target rotational speed and the operation voltage in feedback control at the time of idling, information on the change over time of the fuel injection valve 10 is detected and adjusted based on the detected information. A coefficient was set. Thereby, the dispersion | variation in the injection characteristic resulting from the time-dependent change of the fuel injection valve 10 can be suppressed suitably.

(Fifth embodiment)
Hereinafter, the fifth embodiment will be described with reference to the drawings with a focus on differences from the fourth embodiment.

  FIG. 16 shows a procedure of processing relating to calculation of an adjustment coefficient for compensating for a change with time in the present embodiment. This process is a process repeatedly executed by the ECU 20 at, for example, a predetermined cycle.

  Also in the process shown in FIG. 16, in steps S40 to S44, the same processes as those in steps S30 to S34 shown in FIG. 15 are performed. However, in the process shown in FIG. 16, in step S46, the linear expression for determining the adjustment coefficient is corrected to “α (kact) × P + β (kact) + γ”. Here, each coefficient (and intercept) is corrected by map calculation based on the adjustment coefficient kact calculated in step S44. That is, based on the adjustment coefficient kact having information due to changes over time during idling, how the linear expression changes is determined in advance by experiments or the like, and based on the result, the adjustment coefficient kact and each coefficient of the primary expression Is created and stored in the ECU 20. Thereby, it is possible to suitably correct the linear expression according to the change with time.

  According to this embodiment described above, the following effects can be obtained in addition to the above-described effects of the fourth embodiment.

  (14) Based on the adjustment coefficient kact having information due to changes over time during idling, how the linear expression changes is determined in advance through experiments and the like. Thereby, it is possible to more suitably correct the linear expression according to the change with time.

(Other embodiments)
Each of the above embodiments may be modified as follows.

  The drive circuit for the piezo actuator 52 is not limited to that illustrated in FIG. 11 above, and the drive method for the piezo actuator 52 is not limited to that illustrated in FIG. However, it is desirable that the operation voltage change mode (charging profile and discharging profile) is the same between the ones that are corrected and those that are not corrected.

  As shown in FIG. 17, instead of performing a constant charging speed operation or a constant discharging speed operation when the operating voltage is changed as illustrated in FIG. 4, the constant charging time operation or the constant discharging time operation is exemplified as illustrated in FIG. Even if it performs, the effect of said (1)-(6), (9) in previous 1st Embodiment can be acquired.

  Even if the adjustment coefficient is not set for each of a plurality of values of the fuel injection period and the fuel injection amount, the above (1) to (3) and (5) to (9) of the first embodiment described above. ) And the effect (11) of the second embodiment can be obtained.

  Even if the adjustment coefficient is not set for each of a plurality of values of the fuel pressure, the effects (1) to (4) and (6) to (9) of the previous first embodiment, The effect (10) of the second embodiment can be obtained.

  -Before the fuel injection valve 10 is installed in the engine system, the idling rotational speed control can be performed without performing the process of calculating the adjustment coefficient for compensating the variation in the injection characteristic due to the individual difference of each fuel injection valve 10. Based on the change in operating voltage, information on at least one of individual differences and changes over time can be obtained. For this reason, it is also possible to calculate the adjustment coefficient based on this information. Here, if the adjustment coefficient is calculated immediately after the fuel injection valve 10 is mounted on the engine system, the adjustment coefficient that compensates for individual differences can be calculated.

  In the processing shown in FIG. 15 and FIG. 16, the operating voltage when the actual rotational speed is controlled to the target rotational speed depends on the characteristic change due to the temperature of the piezo actuator 52 or the temperature of the diesel engine. It is desirable to take into account that the effects of characteristic changes are reflected. This may be realized by performing the processes of steps S34 and S36 and the processes of steps S44 and S46 only when the temperature of the diesel engine is within a predetermined temperature range, for example.

  -When operating the actuator to feedback control the rotation state of the output shaft of the diesel engine to the target rotation state, the difference between the reference operation amount for the target rotation state and the operation amount in the feedback control Based on the above, the method for acquiring the unique information is not limited to the method performed at the idle rotation speed control. For example, when the engine output is disconnected from the drive wheels due to deceleration of the vehicle on which the engine system is mounted, fuel injection is performed, and feedback is performed so that the rotational increase amount at that time becomes the target increase amount It may be controlled. Even in this case, the difference between the reference operation amount for setting the target increase amount and the actual operation amount is a quantification of the unique information of the injection characteristics of the fuel injection valve 10. Yes.

  An arithmetic expression that defines the relationship between the fuel pressure and the fuel injection period (fuel injection amount) and the adjustment coefficient is not limited to the primary expression. For example, if the above relationship is expressed using a higher-order polynomial, it is possible to make the correlation coefficient larger than the correlation coefficient illustrated in FIG. 13 in the case illustrated in FIG.

  ・ Approximate the actual injection rate waveform to the target injection rate waveform based on the unique information due to at least one of the individual difference of the fuel injection valve and the change over time about the relationship of the displacement of the nozzle needle to the operation amount of the actuator In order to achieve this, the method of adjusting the operation amount of the actuator is not limited to the method of multiplying the reference operation amount by the adjustment coefficient. For example, the adjustment value may be added to the reference operation amount. Further, instead of correcting the reference operation amount with such an adjustment amount (adjustment coefficient, adjustment value, etc.), the operation amount itself adjusted based on the above information may be stored in the ECU 20.

  The storage means included in the fuel injection valve 10 is not limited to the QR code. Even if the fuel injection valve 10 is not provided with a storage means, the ECU 20 may store the adjustment coefficient directly.

  -The fuel injection control is not limited to one in which the operation voltage is temporarily fixed at each of a plurality of values. For example, if the fuel injection control is performed in such a manner that the operation amount is temporarily fixed at an operation voltage corresponding to an intermediate lift amount between the lift amount corresponding to the injection rate zero and the full lift amount, individual differences of the fuel injection valves 10 In addition, variations in injection characteristics due to changes over time cannot be compensated by adjusting the injection period. For this reason, the application of the present invention is particularly effective. In addition, if fuel injection control is performed to intentionally adjust the change speed of the operation voltage in order to control the fuel injection rate as desired, for example, so that the change in the fuel injection rate has a gradual slope (1 degree In fuel injection control that intentionally changes the change speed of the operation voltage in fuel injection, fuel injection control that adjusts the change speed of the operation voltage independently in each fuel injection, etc.) Variations in the injection characteristics due to changes over time cannot be compensated for by adjusting the injection period. For this reason, the application of the present invention is particularly effective.

  The amount of operation of the piezo actuator 52 is not limited to voltage. However, at this time, the drive control energy of the piezo actuator 52 such as a time integral value of current or a time integral value of product of current and voltage is desirable.

  The configuration of the fuel injection valve 10 is not limited to that illustrated in FIG. For example, instead of including the piezo actuator 52, another actuator may be provided. Further, for example, even when the piezo actuator 52 is provided, the configuration of the power transmission system in which the power of the piezo actuator 52 is transmitted to the nozzle needle 34 is not limited to that illustrated in FIG. In short, any fuel injection valve that can continuously adjust the lift amount of the nozzle needle according to the displacement of the actuator may be used. However, when the force of the fuel supplied to the fuel injection valve is applied in the power transmission system in at least one direction in the same direction and opposite to the power of the actuator, the first embodiment described above. The effects (4) and (5) described above can be particularly suitably achieved.

  ・ In addition, the internal combustion engine is not limited to the diesel engine.

The figure which shows the whole structure of the engine system in 1st Embodiment. Sectional drawing which shows the cross-section of the fuel injection valve in the embodiment. The time chart which illustrates the characteristic dispersion | variation by each individual difference of a some fuel injection valve. The time chart which shows the correction | amendment aspect of the operating voltage of the fuel injection valve in the said embodiment. The time chart which shows the correction | amendment aspect of the operating voltage of the fuel injection valve in the embodiment. The flowchart which shows the procedure of the process concerning correction | amendment of the operating voltage of the fuel injection valve in the embodiment. The figure which shows the measurement point of the fuel-injection aspect in the embodiment. The figure which illustrates the method of memorize | storing the adjustment coefficient which correct | amends an operation voltage in ECU. The time chart of the injection characteristic when charging speed and discharging speed are constant regardless of whether correction is performed. The time chart of the injection characteristic at the time of making charging time and discharge time constant irrespective of the presence or absence of correction | amendment. The circuit diagram which shows the structure of the drive circuit of the piezoelectric actuator with which ECU20 is provided. The time chart which shows the charge operation aspect and discharge operation aspect of a piezo actuator in the said embodiment. The figure which shows the correlation coefficient of the adjustment coefficient calculated based on the linear equation concerning 2nd Embodiment, and the adjustment coefficient calculated based on each measurement. The time chart which shows the correction | amendment mode of the operating voltage in 3rd Embodiment. The flowchart which shows the correction | amendment aspect of the operation voltage in 4th Embodiment. The flowchart which shows the correction | amendment aspect of the operation voltage in 5th Embodiment. The time chart which shows the charge operation aspect and discharge operation aspect of a piezo actuator in the modification of each said embodiment.

Explanation of symbols

  6 ... Common rail, 10 ... Fuel injection valve, 20 ... Electronic control unit (ECU), 52 ... Piezo actuator.

Claims (19)

In the fuel injection control method of adjusting the operation mode of the actuator for the fuel injection valve capable of continuously adjusting the lift amount of the nozzle needle according to the displacement of the actuator,
Based on the fuel injection mode measured when the actuator is operated, the unique information resulting from at least one of the solid difference of the fuel injection valve and the change over time is obtained regarding the relationship of the displacement of the nozzle needle with respect to the operation amount of the actuator. Then, based on the acquired information, the operation amount of the actuator is adjusted to approximate the actual injection rate waveform of the fuel injection valve to the target injection rate waveform.   The target injection rate waveform is realized by temporarily fixing the operation amount with an operation amount corresponding to an intermediate lift amount between a lift amount and a full lift amount at an injection rate of zero. The fuel injection control method according to claim 1, wherein:   3. The fuel injection control method according to claim 1, wherein the target injection rate waveform is realized by a lift waveform that sets a lift amount in multiple stages in one fuel injection.   4. The fuel injection control method according to claim 3, wherein the operation amount of the actuator is adjusted for each operation amount corresponding to each of the multi-stage lift stages.   The adjustment for each operation amount corresponding to each of the multi-stage lift stages is the same as the adjustment value for the operation amount serving as a reference for realizing the target injection rate waveform. 5. The fuel injection control method according to claim 4, wherein the control is performed by adjusting.   The adjustment for each operation amount corresponding to each of the multi-stage lift stages is independently determined with respect to the operation amount serving as a reference for realizing the target injection rate waveform. The fuel injection control method according to claim 4, wherein the fuel injection control method is performed by adjusting the adjustment amount.   7. The fuel injection control method according to claim 5, wherein the adjustment amount is set separately for each of a plurality of values for either the fuel injection period or the fuel injection amount.   The adjustment amount is set based on the measurement of the fuel injection mode at each of several values before the fuel injection valve is installed in the engine system. And a process of setting the adjustment amount by substituting any one of the values into the arithmetic expression after the fuel injection valve is mounted in the system. 8. The fuel injection control method according to claim 7, wherein the fuel injection control method is performed. The fuel injection valve is for injecting fuel in an accumulator that stores fuel in a high-pressure state,
The fuel injection control method according to claim 5, wherein the adjustment amount is set for each of a plurality of values for the fuel pressure in the pressure accumulating chamber.   The adjustment amount is set by determining the relationship between the fuel pressure and the adjustment amount based on the measurement of the fuel injection mode at each of several values of the fuel pressure before the fuel injection valve is mounted on the engine system. A process of creating an arithmetic expression; and a process of setting the adjustment amount by substituting each fuel pressure into the arithmetic expression after the fuel injection valve is mounted in the system. The fuel injection control method according to claim 9.   11. The unique information resulting from the individual difference is acquired by measuring the fuel injection mode before the fuel injection valve is actually mounted on the engine system. A fuel injection control method according to claim 1.   After the fuel injection valve is mounted on the engine system, a process for operating the actuator to feedback control the rotation state of the output shaft of the internal combustion engine to the target rotation state, and to achieve the target rotation state The fuel injection according to claim 1, further comprising: processing for detecting a difference between an operation amount serving as a reference for the operation amount and an operation amount in the feedback control, and acquiring the unique information. Control method.   The fuel injection control method according to claim 1, wherein the actuator is a piezo actuator.   The fuel injection control method according to claim 13, wherein the operation amount is drive control energy of the piezoelectric actuator. The adjustment of the operation amount is performed as a correction for a reference operation amount,
The lift amount increase control is performed while the charge profile for the piezo actuator is set to be the same for the reference operation amount and the corrected operation amount. 15. The fuel injection control method according to 13 or 14. The adjustment of the operation amount is performed as a correction for a reference operation amount,
The lift amount reduction control is performed while the discharge profile for the piezo actuator is the same for the reference operation amount and the corrected operation amount. The fuel injection control method according to any one of 13 to 15. In the fuel injection valve capable of continuously adjusting the lift amount of the nozzle needle according to the displacement of the actuator,
A fuel injection valve characterized by comprising storage means for storing unique information on the relationship between the displacement of the lift amount of the nozzle needle with respect to the operation amount of the actuator due to individual differences of the fuel injection valve. In a fuel injection control device that controls the fuel injection rate by operating the actuator for a fuel injection valve capable of continuously adjusting the lift amount of the nozzle needle according to the displacement of the actuator,
Storage means for storing unique information resulting from a solid difference with respect to a displacement of a lift amount of the nozzle needle with respect to an operation amount of the actuator;
A fuel injection control device comprising: setting means for setting an operation amount of the actuator based on information stored in the storage means. In a fuel injection control device that controls the fuel injection rate by operating the actuator for a fuel injection valve capable of continuously adjusting the lift amount of the nozzle needle according to the displacement of the actuator,
A control means for feedback-controlling the rotation state of the output shaft of the internal combustion engine on which the fuel injection valve is mounted to a target rotation state by operating the actuator;
Storage means for storing a reference value of the operation amount of the actuator for controlling to the target rotation state;
The nozzle relative to the operation amount of the actuator based on the difference between the operation amount of the actuator and the operation amount stored in the storage means when the actual rotation state is set to the target rotation state by the control means. Acquisition means for acquiring information specific to the fuel injection valve regarding the relationship of the displacement of the needle;
A fuel injection control apparatus comprising: a correction unit that corrects an operation amount of the actuator based on information acquired by the acquisition unit.

Images