EP1030047A2 - Krafstoffdrucksteuervorrichtung und Verfahren für ein Hochdruckkraftstoffeinspritzsystem - Google Patents

Krafstoffdrucksteuervorrichtung und Verfahren für ein Hochdruckkraftstoffeinspritzsystem Download PDF

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Publication number
EP1030047A2
EP1030047A2 EP00100737A EP00100737A EP1030047A2 EP 1030047 A2 EP1030047 A2 EP 1030047A2 EP 00100737 A EP00100737 A EP 00100737A EP 00100737 A EP00100737 A EP 00100737A EP 1030047 A2 EP1030047 A2 EP 1030047A2
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EP
European Patent Office
Prior art keywords
fuel
control
pressure
force feed
fuel pressure
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
EP00100737A
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English (en)
French (fr)
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EP1030047A3 (de
EP1030047B1 (de
Inventor
Tatsumasa Sugiyama
Yuuichirou Katou
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Toyota Motor Corp
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Toyota Motor Corp
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Priority claimed from JP03547099A external-priority patent/JP4147669B2/ja
Priority claimed from JP11035468A external-priority patent/JP2000234543A/ja
Application filed by Toyota Motor Corp filed Critical Toyota Motor Corp
Publication of EP1030047A2 publication Critical patent/EP1030047A2/de
Publication of EP1030047A3 publication Critical patent/EP1030047A3/de
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/30—Controlling fuel injection
    • F02D41/38—Controlling fuel injection of the high pressure type
    • F02D41/3809—Common rail control systems
    • F02D41/3836—Controlling the fuel pressure
    • F02D41/3845—Controlling the fuel pressure by controlling the flow into the common rail, e.g. the amount of fuel pumped
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/30—Controlling fuel injection
    • F02D41/38—Controlling fuel injection of the high pressure type
    • F02D41/3809—Common rail control systems
    • F02D41/3827—Common rail control systems for diesel engines
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/02—Circuit arrangements for generating control signals
    • F02D41/14—Introducing closed-loop corrections
    • F02D41/1401—Introducing closed-loop corrections characterised by the control or regulation method
    • F02D2041/1413—Controller structures or design
    • F02D2041/1422—Variable gain or coefficients
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/30—Controlling fuel injection
    • F02D41/38—Controlling fuel injection of the high pressure type
    • F02D2041/389—Controlling fuel injection of the high pressure type for injecting directly into the cylinder
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D2200/00—Input parameters for engine control
    • F02D2200/02—Input parameters for engine control the parameters being related to the engine
    • F02D2200/06—Fuel or fuel supply system parameters
    • F02D2200/0602—Fuel pressure
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D2200/00—Input parameters for engine control
    • F02D2200/02—Input parameters for engine control the parameters being related to the engine
    • F02D2200/06—Fuel or fuel supply system parameters
    • F02D2200/0606—Fuel temperature
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D2250/00—Engine control related to specific problems or objectives
    • F02D2250/31—Control of the fuel pressure
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/30—Controlling fuel injection
    • F02D41/38—Controlling fuel injection of the high pressure type
    • F02D41/40—Controlling fuel injection of the high pressure type with means for controlling injection timing or duration
    • F02D41/406—Electrically controlling a diesel injection pump
    • F02D41/408—Electrically controlling a diesel injection pump of the distributing type

Definitions

  • the present invention relates to a fuel pressure control device and method for a high pressure fuel injection system for controlling fuel pressure within an accumulator piping to follow up the change of target fuel pressure by setting the control input of a fuel pump forcedly feeding a high pressure fuel to the accumulator piping to which fuel injection valves are connected.
  • a high pressure fuel is forcedly fed from a fuel pump to the accumulator piping and injected into the combustion chamber of the engine.
  • the fuel pressure within the accumulator piping i.e., the fuel injection pressure of the fuel injection valve is controlled to follow up target fuel pressure in accordance with an engine operation state by setting the control input of the fuel pump based on a predetermined control gain. If such fuel pressure control is conducted, the atomized particle size of the injected fuel and the like are adapted to the engine combustion state.
  • the control gain is to determine follow-up speed when the fuel pressure within the accumulator piping follows up the change of the target fuel pressure and the control gain is empirically set in order to ensure predetermined control response characteristics.
  • the change speed of the fuel pressure with respect to the predetermined control input differs even if the fuel pump is operated at fixed operation speed (which corresponds to engine rotation speed for a type of the pump driven by an engine output shaft). If the change speed of the fuel pressure, temperature and the like varies greatly, the follow-up speed of the fuel pressure goes beyond an optimum speed range to possibly cause overshoot phenomenon in which the fuel pressure exceeds target fuel pressure or, conversely, undershoot phenomenon in which the fuel pressure requires more than time necessary to reach the target pressure.
  • follow-up speed is detected at a transient time at which fuel pressure shows great fluctuation and a control gain is updated according to the detected follow-up speed. That is to say, if it is judged that the follow-up speed of the fuel pressure is too high, the control gain is decreased by a predetermined quantity. Conversely, if it is judged that the follow-up speed is too low, the control gain is increased by a predetermined quantity.
  • the change speed of the fuel pressure with respect to a predetermined control input becomes excessive depending on the magnitude of the fuel pressure or temperature and excess correction operation for correcting the fuel pressure in response to a slight change of the target fuel pressure is performed, thereby inducing a so-called hunting phenomenon.
  • the above-stated control method cannot handle such a hunting phenomenon, with the result that control response characteristics becomes unstable as in the case of the transition state.
  • the present invention has been made under these circumstances. It is, therefore, an object of the present invention to provide a fuel pressure control device and method for a high pressure fuel injection system capable of constantly ensuring good control response characteristics in a transition state, a stationary state, or whichever.
  • a fuel pressure control device for a high pressure fuel injection system is characterized by comprising control means for setting a control input of a fuel pump forcedly feeding a high pressure fuel to an accumulator piping, to which a fuel injection valve is connected, based on a predetermined control gain and thereby controlling fuel pressure within the accumulator piping so as to follow up a change of target fuel pressure; variable element detection means for detecting a variable element making a change speed of the fuel pressure within the accumulator piping variable with respect to the control input at a predetermined operation speed of the fuel pump; and control gain setting means for variably setting the control gain based on the variable element so as to cancel a variation of the change speed of the fuel pressure caused by the variable element in advance.
  • the control gain is set based on the variable element and the variation of the change speed can be thereby canceled in advance.
  • FIG. 1 is a schematic configuration view of a four-cylinder direct injection diesel engine (to be referred to simply as an engine” hereinafter) 10 and a high pressure fuel injection system of the engine 10.
  • the high pressure fuel injection system is provided with injector 12 disposed corresponding to cylinders #1 to #4 of the engine 10, respectively, a common rail 20 to which the injectors 12 are connected, a fuel pump 30 forcedly feeding a fuel within a fuel tank 14 to the common rail 20 and an electronic control unit (to be referred to as ECU" hereinafter) 60.
  • ECU electronice control unit
  • the common rail 20 functions to accumulate the fuel supplied from the fuel pump 30 at a predetermined pressure and the fuel injection pressure of the injectors 12 is determined based on the fuel pressure (rail pressure) within the common rail 20.
  • a relief valve 22 is attached to the common rail 20. The relief valve 22 is connected to the fuel tank 14 through a relief passage 21.
  • the relief valve 22 is normally held in a closed state. When rail pressure increases to exceed a preset upper limit due to some abnormality, it is turned into an open state to forcedly decrease the rail pressure. It is noted that if the rail pressure is greatly decreased as stated above, the ECU 60 judges that fuel leakage occurs to the fuel force feed system, stops fuel injection and forcedly stops the operation of the engine 10.
  • the injectors 12 are solenoid valves opened and closed by the ECU 60 and inject the fuel supplied from the common rail 20 to the combustion chambers (not shown) of the cylinders #1 to #4, respectively. Each of the injectors 12 is also connected to the fuel tank 14 through the relief passage 21. The fuel leaking into the injectors 12 is returned to the fuel tank 14 through the relief passage 21.
  • the ECU 60 executes control over the fuel force feed quantity of the fuel pump 30, the fuel injection timing of the injectors 12 and fuel injection quantity and consists of a memory 64 storing various control programs, function data and the like, a CPU 62 executing various arithmetic processing and the like.
  • various types of sensors for detecting the operation state of the engine 10, a fuel state within the common rail 20 and the like are connected to the ECU 60 and detection signals are inputted from the respective sensors into the ECU 60.
  • a rotation speed sensor 65 and a cylinder discrimination sensor 66 are provided in the vicinity of a crank shaft (not shown) of the engine 10 and in the vicinity of a cam shaft (not shown), respectively.
  • the ECU 60 calculates the rotation speed (engine rotation speed NE) and rotation angle (crank angle CA) of the crank shaft based on the detection signals inputted from the sensors 65 and 66, respectively.
  • An acceleration sensor 67 is provided in the vicinity of an accelerator (not shown) and outputs a detection signal in accordance with the actuating quantity (accelerator opening ACCP) of the accelerator.
  • the common rail 20 is provided with a fuel sensor 68 from which a detection signal is outputted in accordance with rail pressure (detected fuel pressure PCR).
  • a fuel temperature sensor 69 is provided in the middle of the relief passage 21 and outputs a detection signal in accordance with fuel temperature THF.
  • the ECU 60 detects the accelerator opening ACCP, the detected fuel pressure PCR and the fuel temperature THF based on the detection signals from the sensors 67 to 69, respectively.
  • the fuel pump 30 is provided with a drive shaft 40 rotated by the crank shaft of the engine 10, a feed pump 31 actuated based on the rotation of the drive shaft 40 and a pair of supply pumps (first supply pump 50a and second supply pump 50b) driven by an annular cam 42 formed at the drive shaft 40.
  • the feed pump 31 sucks a fuel within the fuel tank 14 from a suction port 34 through a suction passage 24 and supplies the fuel to the first supply pump 50a and the second supply pump 50b at predetermined feed pressure, respectively.
  • excess fuel supplied to neither the supply pump 50a nor pump 50b is returned to the fuel tank 14 through the relief passage 21 from the relief port 36.
  • the first supply pump 50a and the second supply pump 50b which are of inner cam type, applies further high pressure (e.g., 25 to 180 MPa) to the fuel supplied from the feed pump 31 based on the reciprocating motion of plungers (not shown) and forcedly feeds the pressurized fuel to the common rail 20 through a discharge passage 23 from a discharge port 38.
  • This fuel force feed operation is conducted by the supply pumps 50a and 50b alternately and intermittently.
  • the fuel pump 30 is provided with the first regulation valve 70a and the second regulation valve 70b for regulating the fuel force feed quantities of the supply pumps 50a and 50b, respectively.
  • Each of the regulation valves 70a and 70b consists of a solenoid valve and the opening/closing thereof is driven by the ECU 60.
  • the first regulation valve 70a is opened during the suction stroke of the first supply pump 50a to initiate fuel suction operation and also closed during the suction stroke to stop fuel suction operation.
  • the entire fuel thus sucked is pressurized during a force feed stroke following the suction stroke and forcedly fed to the common rail 20 from the first supply pump 50a.
  • the opening timing of the first regulation valve 70a the fuel force feed quantity of the first supply pump 50a is regulated.
  • the opening timing of the second regulation valve 70b during its suction stroke the fuel force feed quantity of the second supply pump 50b is regulated.
  • the ECU 60 sets the opening timings of the regulation valves 70a and 70b at those in which respective suction strokes initiate and changes only the closing timings during the respective suction strokes, thereby controlling the fuel force feed quantities of the supply pumps 50a and 50b, respectively.
  • the ECU 60 increases the fuel force feed quantities of the supply pumps 50a and 50b by delaying the opening timings of the regulation valves 70a and 70b and thereby elongating their opening timings, and decreases the fuel feed quantities of the supply pumps 50a and 50b by advancing the closing timings and thereby reducing the opening timings of the regulation valves 70a and 70b.
  • the opening and closing timings of the regulation valves 70a and 70b are defined with crank angle as a unit.
  • the closing timing is set as a relative crank angle based on the opening timing. Accordingly, if, for example, fuel force feed operations of the supply pumps 50a and 50b are to be stopped, the closing timings thereof are set at 0° CA" and the regulation valves 70a and 70b are maintained closed during their suction strokes. On the other hand, if the fuel force feed quantities are set to a maximum, opening timings are set at 180° CA" corresponding to the crank angle variation during the suction strokes and the respective regulation valves 70a and 70b are constantly kept opened.
  • the ECU 60 changes the fuel force feed quantity of the fuel pump 30, thereby controlling rail pressure to be coincident with predetermined target fuel pressure. Now, description will be given to how the ECU 60 controls rail pressure hereinafter.
  • the flow chart of FIG. 2 shows processing procedures for controlling fuel pressure (rail pressure) in this embodiment.
  • the ECU 60 executes this processing routine as an interruption processing for every predetermined crank angle.
  • step 100 the ECU 60 calculates a basic opening timing ANGBASE based on the engine rotation speed NE and the fuel injection quantity.
  • This basic opening timing ANGBASE is determined based on the necessary fuel force feed quantity of the fuel pump 30 during the stationary operation of the fuel pump 30, i.e., when the rail pressure is almost equal to target pressure (target fuel pressure PCRTRG) and the target fuel pressure PCRTRG is maintained almost constant.
  • the fuel injection quantity is a value calculated based on the accelerator opening ACCP and the engine rotation speed NE in a routine other than the above routine and stored in the memory 64.
  • the relationship among the basic opening timing ANGBASE, fuel injection quantity and engine rotation speed NE is stored in advance in the memory 64 of the ECU 60 as function data based on characteristics and the like of the engine 10 and of the fuel pump 30.
  • the ECU 60 calculates the basic closing timing ANGBASE by referring to this function data.
  • the ECU 60 calculates a feedback (F/B) control correction term ANGFB and a feed forward (F/F) control correction term ANGFF.
  • the F/B control correction term ANGFB and the F/F control correction term ANGFF are set based on the deviation between the target fuel pressure PCRTRG and the rail pressure and on the change speed of the target fuel pressure PCRTRG, respectively. Detailed procedures for calculating the control correction terms AFGFB and ANGFF will be described later.
  • step 350 it is determined which to select as a fuel pressure control method, F/B control or F/F control based on the next judgment formula (1): ⁇ ⁇ ANGFF > ß ⁇ ANGFB
  • ⁇ " and ⁇ " are weighting coefficients to determine which to emphasize and adopt as a control method during the transition operation of the fuel pump 30, F/B control or F/F control.
  • F/F control is first executed during the transition operation of the fuel pump 30 during which the target fuel pressure PCRTRG suddenly increases.
  • F/F control is switched to F/B control.
  • the weighting coefficient ⁇ by which the F/F control correction term ANGFF is multiplied is set smaller relative to the weighting coefficient ⁇ by which the F/B control correction term ANGFB is multiplied, F/B control is executed in an earlier stage when operation is switched from the transition operation to the stationary operation.
  • the final closing timing ANGFIN is compared with its upper limit 180° CA" and its lower limit 0° CA” in steps 365 to 390 and corrected if necessary. That is, if the final closing timing ANGFIN exceeds 180° CA" ( YES” in step 365), then it is set equal to 180° CA" (in step 370) and if it is below 0° CA" ( YES” in step 380), then it is set equal to 0° CA" (in step 390). Thereafter, the ECU 60 temporarily ends this processing routine.
  • the ECU 60 outputs driving signals, generated based on the above final closing timing ANGFIN, alternately to the regulation valves 70a and 70b in a processing routine other than the above routine, thereby regulating the fuel force feed quantity of the fuel pump 30 and controlling the rail pressure.
  • the rail pressure is gradually converged into the target fuel pressure PCRTRG while being varied with the fuel force feed operation of the fuel pump 30 and the fuel injection operations of the injectors 12.
  • the ECU 60 calculates target fuel pressure PCRTRG based on the fuel injection quantity, the engine rotation speed NE and the like.
  • the relationship among the target fuel pressure PCRTRG, the fuel injection quantity and the engine rotation speed NE is experimentally obtained in advance so that the atomized particle size of the fuel injected from the injectors 12 and the like are adapted to the engine combustion state and stored in the memory 64 of the ECU 60 as function data.
  • the ECU 60 calculates the target fuel pressure PCRTRG with reference to this function data.
  • step 204 the deviation (PCRTRG - PCR) between the target fuel pressure PCRTFG and detected fuel pressure PCR is compared with predetermined determination pressure P1.
  • the value of the detected fuel pressure PCR is that detected periodically based on the detection signal of the fuel pressure sensor 68 in another processing routine and stored in the memory 64 of the ECU 60. In this processing routine, the value of the detected fuel pressure PCR is read out from the memory 64 at need.
  • the fuel feed operation of the fuel pump 30 is intermittently or alternately executed by the supply pumps 50a and 50b. Due to this, even if the final closing timing ANGFIN is calculated based on the detected fuel pressure PCR and the like, there exists a certain delay until the calculation result is reflected as the change of the fuel force feed quantity of the fuel pump 30. Consequently, if the deviation (PCRTFG - PCR) is large, therefore, the rail pressure suddenly increases, then the variation of the rail pressure during this delay period necessarily increases.
  • the determination pressure P1 is used to judge whether or not the variation of the rail pressure during the delay period is measurably large.
  • step 204 if it is judged that the deviation (PCRTRG - PCR) is larger than the determination pressure P1 and the variation of the rail pressure is measurable, processing in steps 206 and 208 are executed to correct the detected fuel pressure PCR based on the variation.
  • the bulk modulus E of the fuel is calculated based on the detected fuel pressure PCR and the fuel temperature THF.
  • the memory 64 of the ECU 60 stores the relationship among the bulk modulus E, the detected fuel pressure PCR and the fuel temperature THF as function data.
  • FIG. 4 shows this function data as a three-dimensional map.
  • the bulk modulus E tends to be higher as the detected fuel pressure PCR is higher and the fuel temperature THF is lower.
  • the ECU 60 refers to the function data when calculating the bulk modulus E.
  • step 208 predicted fuel pressure PCRPRE is calculated in accordance with the following procedures.
  • VCR is the total volume of the common rail 20 and discharge passage 23 (to be referred to as force feed system volume" hereinafter) and set at a constant value in this embodiment.
  • step 210 the ECU 60 sets arithmetic fuel pressure TPCRFB used in various arithmetic operations for F/B control.
  • the arithmetic fuel pressure TPCRFB corresponds to the rail pressure after the change prediction period.
  • the predicted fuel pressure PCRPRE is set as the arithmetic fuel pressure TPCRFB.
  • step 204 if it is judged that the deviation (PCRTRG - PCR) is not greater than the determination pressure P1 and the variation of the rail pressure can be negligible, then the detected fuel pressure PCR is set as arithmetic fuel pressure TPCRFB in step 211.
  • step 212 the arithmetic fuel pressure TPCRFB thus set is subtracted from the target fuel pressure PCRTRG and the subtraction result (PCRTRG - TPCRFB) is set as a deviation ⁇ PCRFB.
  • step 214 the ECU 60 calculates bulk modulus EFB used to calculate the control gain KFB of F/B control based on the arithmetic fuel pressure TPCRFB and fuel temperature THF.
  • the ECU 60 refers to the function data shown in FIG. 4 as in the case of the processing in step 206 and thereby calculates this bulk modulus EFB.
  • ⁇ VPUMP is the variation of the suction quantity of the fuel pump 30 occurring when the final opening timing ANGFIN is changed by a unit angle (1° CA) and, in the fuel pump 30 in this embodiment, the variation of the suction quantity is equal to that of the force feed quantity since all the sucked fuel during the suction stroke is forcedly fed during the force feed stroke.
  • the fuel suction and force feed operations of the fuel pump 30 are conducted by the reciprocating motion of the plunger following the rotation of the cam 42.
  • the reciprocation speed of this plunger is changed according to the rotation phase of the cam 42, i.e., crank angle CA.
  • the variation of the force feed quantity (suction quantity variation) ⁇ VPUMP also differs according to the magnitude of the final closing timing ANGFIN.
  • the suction speed of the fuel pump 30 and the final closing timing ANGFIN have a relationship as shown in, for example, FIG. 6 and the suction speed differs according to the magnitude of the final closing timing ANGFIN. Due to this, as shown therein, if the values of the final closing timing ANGFIN (ANGFIN1, ANGFIN2) differ from each other, the values of the suction quantity variation (areas in the oblique-line regions in FIG. 6) corresponding to the respective values ANGFIN1 and ANGFIN2, i.e., the values of the variation of the force feed quantity ⁇ VPUMP ( ⁇ VPUMP1, VPUMP2) differ as well.
  • the average suction speed (indicated by the two-dot chain line in FIG. 6) during the suction stroke (180° CA) of the fuel pump 30 is calculated and the variation of the suction quantity which occurs when the final closing timing ANGFIN is changed by the unit angle while the suction speed is made constant and equal to the average speed is set as the variation of the force feed quantity ⁇ VPUMP.
  • ANGFB KFB ⁇ ⁇ PCRFB
  • the F/B control correction term ANGFB is calculated based on the control gain KFB reset to be relatively small as is obvious from the above formulas (5) and (6) and the increase of the follow-up speed is therefore avoided in advance.
  • the F/B control correction term ANGFB is calculated based on the control gain KFB reset to be relatively large and the decrease of the follow-up speed can be therefore avoided in advance.
  • FIG. 7 is a flow chart showing procedures for calculating the F/F control correction term ANGFF.
  • the ECU 60 compares target fuel pressure PCRTRG and detected fuel pressure PCR in step 302. Here, if it is judged that the detected fuel pressure PCR is not less than the target fuel pressure PCRTRG, the F/F control correction term ANGFF is set at 0° CA" in step 315 and the processing in this routine is temporarily finished.
  • step 304 the target fuel pressure PCRTRG is subtracted from the previous target fuel pressure value PCRTRG0, the absolute value
  • arithmetic fuel pressure TRCRFF is set equal to the target fuel pressure PCRTRG in step 306.
  • This arithmetic fuel pressure TPCRFF is used for various arithmetic operations for F/F control and, as will be described later, the F/F control correction term ANGFF is calculated based on the deviation (PCRTRG - TPCRFF) between the arithmetic fuel pressure TPCRFF and the target fuel pressure PCRTRG.
  • the subtraction value (PCRTRG - PCRTRG0) is compared with the determination pressure P2 in step 305 and it is thereby judged whether the target fuel pressure PCRTRG is on the increase or on the decrease. If it is judged that the target fuel pressure PCRTRG is on the decrease, the arithmetic fuel pressure TPCRFF is set equal to the target fuel pressure PCRTRG0 in step 308.
  • the target fuel pressure PCRTRG is on the increase in step 305
  • the previous target fuel pressure PCRTRG0 is compared with the detected fuel pressure PCR and the higher pressure is set as arithmetic fuel pressure TPCRFF in step 307.
  • step 307 the deterioration of control characteristics is suppressed. While the target fuel pressure PCRTRG is on the decrease and the rail pressure is higher than the target pressure PCRTRG, if the target fuel pressure PCRTRG starts increasing, the relationship (PCRTRG > PCR > PCRTRG0) may be created, though temporarily, among the magnitudes of the target fuel pressure PCRTRG, the detected fuel pressure PCR and of the previous target fuel pressure PCRTRRG0.
  • step 308 if the arithmetic fuel pressure TPCRFF is set equal to the previous target fuel pressure PCRTRG0, the deviation (PCRTRG - TPCRFF) increases by the difference between the detected fuel pressure PCR and the previous target fuel pressure PCRTRG0. Due to this, the F/F control correction term ANGFF is set at an excessive high value and excess fuel is forcedly fed.
  • the arithmetic fuel pressure TPCRFF is set, it is set not equal to the previous target fuel pressure PCRTRG0 but the detected fuel pressure PCR thereby setting the F/F control correction term ANGFF to be an appropriate value.
  • arithmetic fuel pressure TPCRFF is calculated in the respective steps 306 to 308
  • bulk modulus EFF used to calculate a control gain KFF for F/F control is calculated based on the arithmetic fuel pressure TPCRFF and the fuel temperature THF in step 310.
  • the ECU 60 refers to the function data shown in FIG. 4 as in the case of steps 206 and 214 and thereby calculates the bulk modulus EFF.
  • ⁇ PCRFF is the deviation (PCRTRG - TPCRFF) between the target fuel pressure PCRTRG and the arithmetic fuel pressure TPCRFF.
  • ANGFF0 is the carry-over quantity of the F/F control correction term ANGFF and calculated in the next steps 316 and 318.
  • step 316 the addition value (ANGBASE + ANGFF) of the basic closing timing ANGBASE and the F/F control correction term ANGFF calculated this time is compared with the set upper limit 180° CA" of the addition value.
  • the addition value (ANGBASE + ANGFF) exceeds the upper limit (180° CA)
  • the difference ( ANGBASE + ANGFF - 180° CA ) between the addition value (ANGBASE + ANGFF) and the upper limit (180° CA) is added to the present carry-over quantity ANGFF0 and the resultant addition value ( ANGFF0 + (ANGBASE + ANGFF - 180° CA) ) is set as a new carry-over quantity ANGFF0 in step 318.
  • step 318 After the processing in step 318 is executed or if it is judged that the update of the carry-over quantity ANGFF0 is not necessary in step 316, the ECU 60 sequentially executes processing in step 350 and the following shown in FIG. 2.
  • control gains (KFB, KFF) for F/B control and F/F control, respectively are not constant but reset at intervals at which the control input of the fuel pump 30 (final closing timing ANGFIN) is calculated. If these control gains are set, the magnitudes of the bulk moduli (EFB, EFF) of the fuel are constantly monitored and the magnitudes are reflected in control gain setting. By doing so, the variation of the change speed of the rail pressure relative to the control input (final closing timing ANGFIN) of the fuel pump 30 resulting from the change of the bulk moduli is canceled in advance.
  • the bulk moduli are calculated based on both the fuel pressure and the fuel temperature, they can be accurately detected based on parameters which can be obtained relatively easily and it can be ensured reflecting their variations in control gain setting. Thus, it is possible to ensure good control response characteristics more surely.
  • the abnormality of the fuel temperature sensor 69 means the change of an output signal due to disconnection of connection wiring, the deterioration of sensor elements or the like. Such abnormality detection is made based on the judgement as to whether or not the output signal falls within a predetermined output range in another abnormality judgment processing executed by the ECU 60. Also, if the fuel temperature 69 is judged abnormal in this abnormality determination processing, then an abnormality detection flag XTHF indicating occurrence of abnormality is set ON".
  • each bulk modulus (EFB, EEF) is set lower than the value corresponding to the actual fuel temperature and the control input of the fuel pump 30 (final closing timing ANGFIN) is calculated based on the excessive control gains (KFB, KFF).
  • the rail pressure is controlled based on such excessive control gains (KFB, KFF) and the target fuel pressure suddenly increases to be close to the upper limit of the rail pressure by, for example, the sudden acceleration of the engine 10, the rail pressure may exceed an upper limit and further increases (overshoots) and the relief valve 22 may be opened. As a result, the operation of the engine 10 may be forcedly stopped.
  • the rail pressure decreases (overshoots) to go further below the lower limit
  • the exhaust property may be deteriorated due to the fuel injection at extremely low fuel injection pressure or the engine 10 may be stopped due to inability to conduct normal engine combustion at worst.
  • the ECU 60 calculates the control gain KFB for F/B control in step 215 and then moves to a processing in step 216. In step 216, it is judged whether or not the abnormality detection flag XTHF is ON".
  • the ECU 60 If it is judged that the abnormality detection flag XTHF is ON" and abnormality occurs to the fuel temperature sensor 69, then the ECU 60 resets the control gain KFB in step 217 in accordance with the following procedures.
  • the ECU 60 refers to the function data shown in FIG. 4 and thereby calculates the bulk modulus EFB as in the case of the processing in step 214. It is noted, however, that the ECU 60 calculates the bulk modulus EFB with the fuel temperature THF set as the lowest temperature THFLOW on the function data in step 217.
  • the calculated bulk modulus EFB is, therefore, always the highest value among those with respect to the same arithmetic fuel pressure TPCRFB.
  • the ECU 60 calculates the control gain KFB based on the above formula (5) as in the case of the processing in step 215.
  • the control gain KFB is always calculated to be relatively low in step 217 with respect to the value calculated in step 215.
  • step 218 If it is judged that the fuel temperature sensor 69 is normal in step 216 or after the processing in step 217 is executed, the ECU 60 executes processing in step 218 and the following.
  • the ECU 60 calculates the control gain KFF for F/F control in step 311 and then moves to a processing in step 312. In step 312, it is judged whether or not the abnormality detection flag XTHF is ON".
  • the ECU 60 If it is judged that the abnormality detection flag XTHF is ON" and abnormality occurs to the fuel temperature sensor 69, then the ECU 60 resets the control gain KFF in step 313 in accordance with the following procedures.
  • the ECU 60 refers to the function data shown in FIG. 4 and thereby calculates the bulk modulus EFF again with the fuel temperature THF set at the lowest temperature THFLOW as in the case of the processing in step 217.
  • the calculated bulk modulus EFF is the highest value among those with respect to the arithmetic fuel pressure TPCRFF.
  • control gain KFF is calculated based on the above formula (7). Since the bulk modulus EFF is set relatively high, the control gain KFF is always calculated relative low with respect to the value calculated in step 311.
  • step 312 determines whether the fuel temperature sensor 69 is normal or after the processing in step 313 is executed. If it is judged in step 312 that the fuel temperature sensor 69 is normal or after the processing in step 313 is executed, the ECU 60 executes processing in step 314 and the following.
  • the control gains KFB and KFF are reset based on the bulk moduli EFB, EFF and the like with the fuel temperature set at the lowest temperature THFLOW.
  • control gains KFB and KFF are set at the lowest values compared with those set with respect to the arithmetic fuel pressures TPCRFB and TPCRFF, respectively.
  • the absolute values of the F/B control correction term ANGFB and F/F control correction value ANGFF are also set at relatively low values. Therefore, even if either F/F control or F/B control is selected as a fuel pressure control method, the change speed of the final closing timing ANGFIN is lower than the normal value and the change speed of the rail pressure is suppressed, so that the rail pressure follows up more gradually the change of the target fuel pressure (PCRTRG).
  • the procedures for setting the control gains KFB and KFF are changed based on the abnormality of the fuel temperature sensor 69.
  • control gains KFB and KFF can be set at constant values.
  • the constant values may involve, for example, the minimum values of the control gains KFB and KFF.
  • the control gains KFB and KFF when the control gains KFB and KFF are calculated, the total volume of the common rail 20 and the discharge passage 23, i.e., the force feed system volume VCR is set at a constant value. If a structure in which the volume of the common rail 20 and the length of the discharge passage 23 are variable is adopted, the control gains KFB and KFF may be changed based on the magnitude of the force feed system volume VCR.
  • the present force feed system volume VCR is detected in the both steps and the detected volume VCR is assigned to the formulas (5) and (7) and then the control gains KFB and KFF are calculated.
  • the control gains KFB and KFF are set higher. Therefore, in addition to the bulk moduli (EFB, EFF), the follow-up speed of the rail pressure can be maintained to be appropriate speed despite the change of the force feed system volume VCR.
  • the variation of the suction quantity when changing the final closing timing ANGFIN by a unit angle at the average suction speed during the suction stroke of the fuel pump 30 (180° CA), is set as the above-stated variation of the force feed quantity ⁇ VPUMP and the variation ⁇ VPUMP is used to operate the control gains KFB and KFF.
  • the magnitude of the suction speed varies according to the final closing timing ANGFIN. Due to this, if the final closing timing ANGFIN falls within an angle range A2, the variation of the force feed quantity ⁇ VPUMP is estimated slightly larger than the actual variation and the control gains KFB and KFF of the fuel pump 30 may be set relatively low. On the other hand, if the final closing timing ANGFIN falls within an angle range A4, the variation ⁇ VPUMP is estimated slightly smaller than the actual variation and the control gains KFB and KFF are set relatively high. Thus, it is preferable to consider the operation characteristics of the fuel pump 30 in order to accurately obtain the control gains KFB and KFF.
  • the correction term f (KA n , EFF, ⁇ PCRFF) is calculated based on the correction coefficient KA n , the bulk modulus EFF, the deviation PCREF and the carry-over quantity ANGFF0. Thereafter, the correction term f is added to the final closing timing ANGFIN calculated in step 360 and the addition value is reset as a new final closing timing ANGFIN.
  • control gains KFB and KFF are corrected substantially based on the difference in the variation of the force feed quantity ⁇ VPUMP with respect to the final closing timing ANGFIN and the error of the final closing timing ANGFIN due to those of the control gains KFB and KFF can be corrected.
  • the relationship between the force feed quantity variation ⁇ VPUMP and the final closing timing ANGFIN varies, as the operation characteristics of the fuel pump 30, according to the final closing timing ANGFIN and the follow-up speed of the rail pressure with respect to the target fuel pressure is changed due to the variation, the change can be canceled in advance and the follow-up speed can be maintained to be an appropriate value.
  • the bulk moduli EFB and EFF can be regarded as constant values and the control gains KFB and KFF can be set merely based on the force feed system volume VCR and the force feed quantity variation ⁇ VPUMP.
  • the bulk moduli (EFB, EFF) of the fuel are calculated based on both the fuel pressure and the fuel temperature. It is also possible to calculate them while either the fuel pressure or the fuel temperature is regarded constant.
  • the fuel temperature can be estimated based on parameters changing in correlation with the fuel temperature, e.g., the temperature of cooling water of the engine 10.
  • the discharge passage 23 from the fuel pump 30 to the common rail 20 is common to the supply pumps 50a and 50b. If the discharge passage 23 is provided for each of the supply pumps 50a and 50b, the force feed system volume VCR may be changed for each of the supply pumps 50a and 50b to thereby calculate the control gains (KFB, KFF) for F/B control and F/F control.
  • the variation ⁇ VPUMP may be changed for each of the supply pumps 50a and 50b to thereby calculate the control gains (KFB, KFF).
  • the rail pressure can be controlled only by either F/B control or F/F control.
  • FIGS. 11A and 11B show the cross-sectional structure of the supply pumps 50a and 50b taken along line 11-11 of FIG. 1 and the schematic configuration view of fuel passages in the fuel pump 30.
  • the first supply pump 50a has a cylindrical support 43 formed in a housing 41 (see FIG. 1) of the fuel pump 30, a pair of plungers 54a supported to be movable in a reciprocating manner by a through hole 43a formed in the support 43 and the like, the first pressurizing chamber 52a determined by the inner end faces of the plungers 54a and the inner wall of the through hole 43a, and the like.
  • a shoe 55a is formed at the outer end portion of each of the plungers 54a and a roller 56a is rotatably supported by the shoe 55a.
  • a cam face 42c against which each roller 56a can be abutted has an ellipsoidal cross section. Due to this, if the cam 42 rotates following the rotation of the drive shaft 40, the length La between the cam faces 42c in the reciprocating direction of the plungers 54a is increased and decreased according to the rotation. Therefore, if the cam 42 rotates while the rollers 56a are abutted against the cam faces 42c, respectively, the plungers 54a reciprocate such that they are close to and distant from each other. The volume of the first pressurizing chamber 52a is changed according to the reciprocating motions. It is assumed hereinafter that a period in which the distance La between the cam faces 42 increases is a suction stroke" of the first supply pump 50a and that in which the distance La decreases is a force feed stroke".
  • the drive shaft 40 has a deceleration ratio to a crank shaft set at 1/2 and rotates once whenever the crank shaft rotates twice. Therefore, while the cylinders #1 to #4 perform one-cycle operation including suction, compression, expansion and exhaust while the crank shaft rotates twice, the suction stroke and the force feed stroke are alternately conducted twice in the first supply pump 50a.
  • the first pressurizing chamber 52a is connected to the field pump 31 through a non-return valve 44a and the first regulation valve 70a and connected to a discharge port 38 through another non-return valve 46a.
  • the non-return valves 44a and 46a restrict the flow of a fuel from the first pressurizing chamber 52a toward the field pump 31 and that from the discharge port 38 toward the first pressurizing chamber 52a, respectively, so that the fuel flows generally from the field pump 31 toward the common rail 20 through the first supply pump 50a.
  • the first supply pump 50a, the first regulation valve 70a, the non-return valves 44a and 46a, the common rail 20, the field pump 31 and fuel passages connecting them as stated above constitute the first fuel force feed system as a whole.
  • the fuel is supplied into the first pressurizing chamber 52a from the field pump 31 through the non-return valve 44a.
  • the entire fuel thus supplied into the first pressurizing chamber 52a is forcedly fed to the discharge port 38 from the first pressurizing chamber 52a through the non-return valve 46a in the force feed stroke of the first supply pump 50a.
  • the second supply pump 50b is also of inner cam type and provided with the second pressurizing chamber 52b, plungers 54b, shoes 55b, rollers 56b and the like as in the case of the first supply pump 50a.
  • a through hole 43b supporting the plunger 54b so as to allow the plunger 54b to reciprocate is formed to extend in the direction orthogonal to the through hole 43a of the first supply pump 50a. Due to this, if it is assumed that a period in which the length Lb between cam faces 42c in the reciprocating directions of the plungers 54b is a suction stroke" of the second supply pump 50b and that in which the length Lb decreases is a force feed stroke" thereof, the suction stroke and force feed stroke of the second supply pump 50b have phases, as crank angles CA, shifted by 180° CA from the suction stroke and the force feed stroke of the first supply pump 50a, respectively.
  • the second pressurizing chamber 52b has the same structure as that of the first pressurizing chamber 52a.
  • the chamber 52a is connected to the field pump 31 through a non-return valve 44b and the second regulation valve 70b and also connected to the discharge port 38 through another non-return valve 46b.
  • the second supply pump 50b, the second regulation valve 70b, the non-return valves 44b and 46b, the common rail 20, the field pump 31 and the fuel passages connecting them as stated above constitute the second fuel force feed system as a whole.
  • FIG. 12 is a timing chart showing the change mode of the rail pressure in a stationary state in which the target value of the rail pressure (target fuel pressure PCTRG) is maintained almost constant, the fuel force feed and suction operation timing of the supply pumps 50a and 50b with respect to the crank angle CA and the like.
  • the rail pressure is constantly changed by the fuel force feed operations ((b), (c)) of the supply pumps 50a and 50b and by the fuel injection operations of the injectors (12) ((d)) even in the stationary state.
  • the reason that the rail pressure slightly decreases even in periods in which neither the fuel force feed operation nor the fuel injection operation is executed is that a small quantity of the fuel from the injectors 12 is constantly returned to the fuel tank 14 through the relief passage 21.
  • the force feed operations of the supply pumps 50a and 50b and the fuel injection operations of the injectors 12 are executed while maintaining their predetermined relationships with respect to the crank angle CA. For example, in a period in which the crank angle CA is [CA1 to CA2], the fuel injection of the injector 12 corresponding to the first cylinder #1 and the fuel force feed operation of the second supply pump 50b are conducted. In a period in which the crank angle CA is [CA2 to CA3], the fuel injection of the injector 12 corresponding to the third cylinder #3 and the fuel force feed operation of the first supply pump 50a are conducted.
  • Symbol (e) in FIG. 11 indicates the detection timing at which actual fuel pressure PCR is detected by the ECU 60.
  • the actual fuel pressure PCR is detected at predetermined crank angle intervals (180° CA's intervals).
  • the detection timing is set at timing (CA1, CA2, CA3, CA4) at which the rise of the rail pressure by the fuel force feed operations of the supply pumps 50a and 50b end.
  • Symbol (f) in FIG. 11 indicates the change mode of the determination counter value CPCYLND.
  • This determination counter value CPCYLND is used to conduct processing for calculating the control inputs of the supply pumps 50a and 50b, i.e., the opening timings of the regulation valves 70a and 70b and is incremented by one at predetermined crank angle (180° CA) intervals in the mode of [.. ⁇ 0 ⁇ 1 ⁇ 2 ⁇ 3 ⁇ 0 ⁇ ..] in a counter value operation routine.
  • the determination counter value CPCYLND is set at 1" or 3" when the actual fuel pressure PCR is detected, it can be judged that the actual fuel pressure PCR corresponds to the rail pressure which has risen by the fuel force feed operation of the first supply pump 50a. If the determination counter value CPCYLND is set at 0" or 2", it can be judged that the actual fuel pressure PCR corresponds to the rail pressure which has risen by the fuel force feed operation of the second supply pump 50b.
  • the closing timings (final closing timing ANGFIN) of the regulation valves 70a and 70b are calculated and the fuel suction quantities of the supply pumps 50a and 50b are changed based on the final closing timing ANGFIN, thereby feedback-controlling the pressure of the fuel forcedly fed from the supply pumps 50a and 50b to coincide with the target value (target fuel pressure PCRTRG).
  • a fuel pressure control routine" shown in these flow charts is executed by the ECU 60 as interruption processing at predetermined crank angle (180° CA) intervals.
  • the detection of actual fuel pressure PCR is conducted as part of processing this fuel pressure control routine".
  • the interruption timing of the fuel pressure control routine is set, as the detection timing of the actual fuel pressure PCR, at timing (CA1, CA2, CA3 and CA4 shown in FIG. 12) at which the rise of the rail pressure by the force feed operations of the fuel of the supply pumps 50a and 50b ends as already described above.
  • the ECU 60 detects actual fuel pressure PCR in step 410 and then calculates target fuel pressure PCRTRG based on the fuel injection quantity and engine rotation speed NE in step 420.
  • the relationship among the target fuel pressure PCRTRG, the fuel injection quantity and the engine rotation speed NE is experimentally obtained so that the atomized particle size and the like of the injected fuel are adapted to an engine combustion state, and stored in the memory 64 of the ECU 60 as function data for calculating the target fuel pressure PCRTRG.
  • the fuel injection quantity is calculated based on the accelerator opening ACCP, the engine rotation speed NE and the like and stored in the memory 64.
  • step 430 the ECU 60 calculates a basic closing timing ANGBASE based on the fuel injection quantity, the actual fuel pressure PCR and the engine rotation speed NE.
  • the proportional term ANGPRO is to conduct proportional operation in so-called PID control (or particularly PI control in this case) and is a correction angle for correcting the basic closing timing ANGBASE according to the magnitude of the deviation ⁇ PCR.
  • Symbol K P is a proportional gain and set based on the average force feed characteristics of the respective fuel force feed systems.
  • step 460 the ECU 60 judges whether or not update prohibition conditions for an integral term ANGINT are satisfied.
  • This integral term ANGINT is conducts integral operation in PID control and is a correction angle for correcting the basic closing timing ANGBASE according to the magnitude of the integral value of the deviation ⁇ PCR.
  • the update prohibition conditions are that the previous value ANGFIN0 of the final closing timing ANGFIN is a maximum 180° CA" or a minimum 0° CA", i.e., the rail pressure is in a transition state. That is to say, the integral term ANGINT is used to cancel the stationary deviation remaining between the rail pressure and the target fuel pressure PCRTRG when the rail pressure becomes almost equal to the target fuel pressure PCRTRG. Due to this, the update of the integral term ANGINT is prohibited in the transition state in which the rail pressure suddenly increases.
  • the ECU 60 calculates the integral term ANGINT based on the update quantity DANGINT in step 355.
  • values ANGINT1 and ANGINT2 of the integral term ANGINT corresponding to the fuel force feed systems are prepared and these values ANGINT1 and ANGINT2 are individually updated synchronously with the fuel force feed operations of the respective fuel force feed systems and stored in the memory 64.
  • step 502 the ECU 60 judges whether the above-stated determination counter value CPCYLND is 0" or 2", i.e., whether or not the final closing timing ANGFIN to be calculated this time is intended to operate the second fuel force feed system (the second regulation valve 70b of the second supply pump 50b).
  • the integral term ANGINT is set to correspond to the second fuel force feed system in steps 510 to 514.
  • the ECU 60 judges whether or not the deviation ⁇ PCR is higher than 0", i.e., whether or not the target fuel pressure PCRTRG exceeds the actual fuel pressure PCR.
  • the ECU 60 reads out the value ANGINT2 of the integral term ANGINT (integral term ANGINT2) corresponding to the second fuel force feed system from the memory 64, updates a value (ANGINT2 + DANGINT) obtained by adding the update quantity DANGINT to the integral term ANGINT2 as a new integral term ANGINT2 and stores the new integral term ANGINT2 in the memory 64 in step 212.
  • the ECU 60 updates a value (ANGINT2 - DANGINT) obtained by subtracting the update quantity DANGINT from the value ANGINT2 of the integral value ANGINT as a new integral term ANGINT2 and stores the new integral term ANGINT2 in the memory 64 in step 213.
  • the update quantity DANGINT is set at 0° CA" and the update of the integral term ANGINT2 in step 212 or 213 is not, therefore, substantially executed.
  • the integral term ANGINT2 is integrated based on the deviation ⁇ PCR generated by the fuel force feed operation of the second fuel force feed system.
  • step 514 the ECU 60 sets the integral term ANGINT2 thus updated corresponding to the second fuel force feed system as a final integral term ANGINT.
  • the ECU 60 integrates the value ANGINT1 of the integral term ANGINT corresponding to the first fuel force feed system in steps 520 to 524 as in the case of the processing in steps 510 to 514 and sets the resultant value as a final integral term ANGINT.
  • the ECU 60 judges whether or not the integral term ANGINT finally set and the integral terms ANGINT1 and ANGINT2 of the respective fuel force feed systems stored in the memory 64 fall within a predetermined angle range in step 540.
  • the ECU 60 corrects the integral term ANGINT, ANGINT1 or ANGINT2 which is out of the predetermined angle range, to be equal to the upper limit angle or the lower limit angle in step 242.
  • step 240 After correcting the integral term ANGINT, ANGINT1 or ANGINT2 as stated above or if it is judged that correction is not necessary in step 240, then the ECU 60 moves to a processing in step 300 shown in FIG. 4.
  • step 300 the ECU 60 adds together the basic closing timing ANGBASE, the proportional term ANGPRO and the integral term ANGINT and sets the addition value ( ANGBASE + ANGPRO + ANGINT ) as a final closing timing ANGFIN.
  • step 302 the present final closing timing ANGFIN is set as the previous value ANGFIN0. Thereafter, the ECU 60 temporarily finishes a series of processing steps.
  • the ECU 60 generates a driving signal based on the final closing timing ANGFIN in another routine and outputs the driving signal to the regulation valves 70a and 60b alternately. For example, if the final closing timing ANGFIN is calculated at the timing CA1 and the timing CA3 shown in FIG. 3, the driving signal based on the final closing timing ANGFIN is outputted to the first regulation valve 70a. If the final closing timing ANGFIN is calculated at the timing CA2 and the timing CA4, the driving signal is outputted to the second regulation valve 70b. As a result, the rail pressure is controlled to coincide with the target fuel pressure PCRTRG.
  • the integral terms ANGINT are updated individually for the fuel force feed systems and the final closing timing ANGFIN is calculated based on the values ANGINT1 and ANGINT2 of the integral term ANGINT corresponding to the respective fuel force feed systems.
  • Main factors for the change of the force feed characteristics of the fuel force feed systems with the passage of time involve, for example, the increase of sliding resistance between the plungers 54a and 54b and the inner walls of the through holes 43a and 43b of the supply pumps 50a and 50b, respectively, the decrease of the response speed of the regulation valves 70a and 70b and the elongation of response delay time from the input of the closing driving signal to the closure of the regulation valves 70a and 70b.
  • Symbol (a) in FIG. 15 indicates the change mode of the rail pressure if the force feed capability of the first fuel force feed system deteriorates due to the above-stated increase of sliding resistance and the actual fuel pressure PCR after completing the force feed operation of the pump 50a in a stationary state is always below the target fuel pressure PCRTRG.
  • the integral term ANGINT is updated for each fuel force feed system even in the above case. Due to this, only the control input (final closing timing ANGFIN) of the first fuel force feed system which force feed capability has deteriorated is increases following the update of the integral term ANGINT. As shown in symbol (c) of FIG. 15, therefore, it is possible to control only the fuel pressure of the first fuel force feed system to coincide with the target fuel pressure PCRTRG without adversely influencing the fuel force feed operation of the second fuel force feed system and to suppress the irregular fuel injection quantity and the deterioration of the exhaust property.
  • the difference in force feed characteristics between the fuel force feed systems can be reflected in the calculation of the respective control inputs (final closing timing ANGFIN). It is, therefore, possible to ensure suppressing the stationary deviation from remaining between the rail pressure and the target fuel pressure and to thereby enhance control characteristics at the time of converging the rail pressure into the target fuel pressure.
  • the proportional gain K P is switched for the fuel force feed operation of each fuel force feed system to thereby calculate the proportional term ANGPRO in addition to the update of an integral term ANGINT for each fuel force feed system.
  • FIG. 16 is a flow chart showing the processing content of step 450 of FIG. 13 in detail.
  • step 140 shown in FIG. 13 in which the deviation ⁇ PCR is calculated the ECU 60 moves to the processing in step 152 in FIG. 16.
  • step 152 it is judged whether the determination counter value CPCYLND is 0" or 2", i.e., whether or not a final closing timing ANGFIN to be calculated this time is intended to operate the second fuel force feed system.
  • the proportional gain K P is set at a value K P 2 corresponding to the second fuel force feed system in step 154.
  • the proportional gain k P is set at a value K P 1 corresponding to the first fuel force feed system in step 155.
  • the values K P 1 and K P 2 are preset ones based on the force feed characteristics of the respective fuel force feed systems experimentally or the like.
  • the force feed characteristics mentioned herein involve, for example, the fuel force feed quantities of the supply pumps 50a and 50b with respect to a predetermined final closing timing ANGFIN, the total volume of portions from the supply pumps 50a and 50b to the common rail 20 among the common rail 20 and the fuel passages and channel resistance of the respective fuel passages. If response characteristics of the fuel force feed operations of the fuel force feed systems are low such as, for example, in a case where the fuel force feed quantities are relatively low or the channel resistance is relatively high, then the values K P 1 and K P 2 of the proportional gain K P are set relatively high. If the response characteristics of the fuel force feed systems differ from each other, therefore, the values K P 1 and K P 2 are set different from each other according to the difference in response characteristics.
  • the ECU 60 calculates the proportional term ANGPRO based on the above formula (9) in step 456. Then, by executing processing in step 160 and the following shown in FIG. 2, the final closing timing ANGFIN is calculated based on the proportional term ANGPRO.
  • the increase quantity of the rail pressure corresponding to the predetermined control input (final closing timing ANGFIN) is almost equal. This allows the rail pressure to follow up the transitional change of the target fuel pressure at appropriate follow-up speed and control characteristics at the time of converging the rail pressure into the target fuel pressure to enhance.
  • the rail pressure is be allowed to follow up the change of the target fuel pressure at almost constant follow-up speed and to, therefore, suppress the irregular fuel injection quantities and the deterioration of the exhaust property as described above.
  • the abnormality of the fuel force feed systems can be detected based on the magnitudes of the values ANGINT1 ad ANGINT2 of the integral terms ANGINT updated for the supply pumps 50a and 50b, respectively.
  • step 540 If abnormality is to be detected, after processing in steps 514 and 524 in FIG. 14, processing shown in the flow chart of FIG. 17 are executed prior to those in step 540 and the following.
  • step 530 the absolute value
  • This abnormality detection deviation ⁇ K is used to judge to which fuel force feed system abnormality occurs. If the fuel force feed operation of one of the fuel force feed systems is not normally conducted, only one of the values ANGINT1 and ANGINT2 of the integral term ANGINT is increased and the abnormality detection deviation ⁇ K is, therefore, increased.
  • step 532 it is judged whether or not the abnormality detection deviation ⁇ K is larger than a predetermined determination value ⁇ K1. If the deviation ⁇ K is larger than the determination value ⁇ K1, it is judged that abnormality occurs to one of the fuel force feed systems and an abnormality flag XPUMP indicating the abnormality is set ON" in step 534.
  • the types of the abnormality of the fuel force feed systems detected herein involve, for example, the stuck plungers 54a and 54b resulting from the excessive increase of the sliding resistance, malfunctions of the regulation valves 70a and 70b and fuel leakage from the fuel passages.
  • step 534 After the processing in step 534 is executed or if it is judged in step 532 that the abnormality determination deviation ⁇ K is not more than the determination value ⁇ K1 and that the force feed operations of the respective fuel force feed systems are executed normally, the processing in step 540 and the following shown in FIG. 14 are executed.
  • the fuel force feed quantity of the other supply pump 50a or 50b is increased by feedback control so as to cancel the deviation between the rail pressure and the target fuel pressure deriving from the lowering of the force feed capability. Consequently, with a structure in which abnormality is detected based on the magnitude of the integral term ANGINT updated in common irrespectively of the fuel force feed systems, the variation width of the integral term ANGINT becomes smaller, with the result that abnormality cannot be detected or such detection is delayed.
  • of the values ANGINT1 and ANGINT2 of the integral term ANGINT may be compared with a predetermined determination value, respectively, and the abnormality of the respective fuel force feed systems may be detected individually based on the fact that the absolute values
  • the basic closing timing ANGBASE may be set individually for the fuel force feed systems, respectively in addition to the integral term ANGINT or the proportional term ANGPRO.
  • a differential term obtained by multiplying the differential value of the deviation ⁇ PCR by a predetermined gain can be used in addition to the above-stated proportional term ANGPRO and the integral term ANGINT. In that case, it is also possible to set the differential term for fuel force feed systems, respectively.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Electrical Control Of Air Or Fuel Supplied To Internal-Combustion Engine (AREA)
  • Fuel-Injection Apparatus (AREA)
  • Combined Controls Of Internal Combustion Engines (AREA)
EP20000100737 1999-02-15 2000-01-14 Krafstoffdrucksteuervorrichtung und Verfahren für ein Hochdruckkraftstoffeinspritzsystem Expired - Lifetime EP1030047B1 (de)

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JP3546899 1999-02-15
JP03547099A JP4147669B2 (ja) 1999-02-15 1999-02-15 内燃機関の燃料圧制御装置
JP11035468A JP2000234543A (ja) 1999-02-15 1999-02-15 高圧燃料噴射系の燃料圧制御装置
JP3547099 1999-02-15

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EP1281860A2 (de) 2001-08-02 2003-02-05 Siemens Aktiengesellschaft Einspritzanlage für eine Brennkraftmaschine und Verfahren zu deren Betrieb
WO2003078817A1 (de) * 2002-03-14 2003-09-25 Robert Bosch Gmbh Verfahren zum betrieben eines kraftstoffzumesssystems eines kraftfahrzeugs, computerprogramm, steuergerät und kraftstoffzumesssystem
EP1136686A3 (de) * 2000-03-23 2004-04-07 Toyota Jidosha Kabushiki Kaisha Einrichtung zur Regelung des Kraftstoffdrucks einer Brennkraftmaschine
EP1304471A3 (de) * 1999-02-19 2004-05-19 Toyota Jidosha Kabushiki Kaisha Einrichtung zur Brennstoffdrucksteuerung
WO2005111402A1 (de) * 2004-05-12 2005-11-24 Mtu Friedrichshafen Gmbh Verfahren zur druck-regelung eines speichereinspritzsystems
EP1371836A3 (de) * 2002-06-10 2006-05-17 Nissan Motor Company, Limited System für die Kraftstoffzufuhr in einer Brennkraftmaschine
DE102005058966B3 (de) * 2005-12-09 2007-08-02 Siemens Ag Verfahren zur Adaption einer Vorsteuerung in einer Druckregelung für eine Common-Rail-Einspritzanlage für eine Brennkraftmaschine und Mittel zur Durchführung des Verfahrens
EP1900930A1 (de) * 2006-09-05 2008-03-19 Denso Corporation Verfahren und Vorrichtung für ein Druckminderungsventil zur Reduktion des Brennstoffdrucks in einer öffentlichen Leitung
US7556023B2 (en) * 2007-03-26 2009-07-07 Hitachi, Ltd. Control device for high-pressure fuel system
CN102374055A (zh) * 2011-09-22 2012-03-14 中国汽车技术研究中心 发动机轨压预控制及反馈控制装置及控制系统和控制方法
DE102007000175B4 (de) * 2006-03-27 2013-01-31 Denso Corporation Kraftstoffeinspritzsteuergerät
US8516995B2 (en) 2009-08-18 2013-08-27 Delphi Technologies Holding S.Arl Control method for a common rail fuel pump and apparatus for performing the same
DE102006035826B4 (de) * 2006-01-31 2014-03-27 Mitsubishi Electric Corp. Hochdruck-Kraftstoffpumpensteuervorrichtung für einen Verbrennungsmotor

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Cited By (17)

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EP1304471A3 (de) * 1999-02-19 2004-05-19 Toyota Jidosha Kabushiki Kaisha Einrichtung zur Brennstoffdrucksteuerung
EP1136686A3 (de) * 2000-03-23 2004-04-07 Toyota Jidosha Kabushiki Kaisha Einrichtung zur Regelung des Kraftstoffdrucks einer Brennkraftmaschine
EP1281860A2 (de) 2001-08-02 2003-02-05 Siemens Aktiengesellschaft Einspritzanlage für eine Brennkraftmaschine und Verfahren zu deren Betrieb
WO2003078817A1 (de) * 2002-03-14 2003-09-25 Robert Bosch Gmbh Verfahren zum betrieben eines kraftstoffzumesssystems eines kraftfahrzeugs, computerprogramm, steuergerät und kraftstoffzumesssystem
US7243636B2 (en) 2002-03-14 2007-07-17 Robert Bosch Gmbh Method for operating a fuel measurement system in a motor vehicle, computer program, control device and fuel measurement system
EP1371836A3 (de) * 2002-06-10 2006-05-17 Nissan Motor Company, Limited System für die Kraftstoffzufuhr in einer Brennkraftmaschine
WO2005111402A1 (de) * 2004-05-12 2005-11-24 Mtu Friedrichshafen Gmbh Verfahren zur druck-regelung eines speichereinspritzsystems
DE102005058966B3 (de) * 2005-12-09 2007-08-02 Siemens Ag Verfahren zur Adaption einer Vorsteuerung in einer Druckregelung für eine Common-Rail-Einspritzanlage für eine Brennkraftmaschine und Mittel zur Durchführung des Verfahrens
US7827963B2 (en) 2005-12-09 2010-11-09 Continental Automotive Gmbh Method of adapting close-loop pressure control in a common-rail injection system for an internal combustion engine and means for executing the method
DE102006035826B4 (de) * 2006-01-31 2014-03-27 Mitsubishi Electric Corp. Hochdruck-Kraftstoffpumpensteuervorrichtung für einen Verbrennungsmotor
DE102007000175B4 (de) * 2006-03-27 2013-01-31 Denso Corporation Kraftstoffeinspritzsteuergerät
EP1900930A1 (de) * 2006-09-05 2008-03-19 Denso Corporation Verfahren und Vorrichtung für ein Druckminderungsventil zur Reduktion des Brennstoffdrucks in einer öffentlichen Leitung
US7848868B2 (en) 2006-09-05 2010-12-07 Denso Corporation Method and apparatus for pressure reducing valve to reduce fuel pressure in a common rail
US7556023B2 (en) * 2007-03-26 2009-07-07 Hitachi, Ltd. Control device for high-pressure fuel system
US8516995B2 (en) 2009-08-18 2013-08-27 Delphi Technologies Holding S.Arl Control method for a common rail fuel pump and apparatus for performing the same
CN102374055A (zh) * 2011-09-22 2012-03-14 中国汽车技术研究中心 发动机轨压预控制及反馈控制装置及控制系统和控制方法
CN102374055B (zh) * 2011-09-22 2014-05-28 中国汽车技术研究中心 发动机轨压预控制及反馈控制装置及控制系统和控制方法

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