JP4147669B2 - Fuel pressure control device for internal combustion engine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention includes a plurality of fuel pumping systems that pump fuel to a fuel injection valve of an internal combustion engine, and the operation amount of each fuel pumping system is set so that the fuel pressure in each fuel pumping system matches the target fuel pressure. The present invention relates to a fuel pressure control device for an internal combustion engine that is calculated.
[0002]
[Prior art]
In a fuel supply system for an internal combustion engine having a stock pressure pipe such as a common rail, the fuel pressure-fed from the fuel pump to the accumulator pipe is injected into the engine combustion chamber from a fuel injection valve connected to the accumulator pipe. ing. As a fuel pump of such a fuel supply system, one having a plurality of fuel pumping systems capable of independently controlling the pumping amount, for example, a plunger type pump, is described in JP-A-6-33845. As such, one having a plurality of plungers is known. By adopting such a fuel pump, the number of times of fuel pumping can be increased relatively easily, and it is possible to suppress fuel injection pressure fluctuations as much as possible by pumping fuel each time fuel injection is performed. .
[0003]
In general, in the fuel supply system, the operation amount of the fuel pump is calculated based on the deviation between the fuel pressure in the pressure accumulation pipe and the target fuel pressure, and the fuel pump is operated based on the operation amount. Thus, the fuel pressure in the pressure accumulating pipe, that is, the fuel injection pressure is controlled so as to follow the change in the target fuel pressure in accordance with the engine operating state. By executing such fuel pressure control, the spray particle size of the injected fuel is adapted to the engine combustion state.
[0004]
[Problems to be solved by the invention]
However, in a fuel supply system that employs a fuel pump having a plurality of fuel pumping systems as described above, if the pumping characteristics of each fuel pumping system are set differently, or if these pumping characteristics are time-dependent If the difference is different, the operation amount is calculated without reflecting the difference in the pumping characteristics in each fuel pumping system, and each fuel pumping system is controlled based on the operation amount. Become.
[0005]
As a result, at the time of fuel pumping of a specific fuel pumping system, the follow-up speed when the fuel pressure is made to follow the change in the target fuel pressure becomes excessive or too small, or the steady-state between the target fuel pressure and the fuel pressure. Deviation may remain, and deterioration of controllability when the fuel pressure is converged to the target fuel pressure is inevitable.
[0006]
The present invention has been made in view of such conventional circumstances, and an object thereof is to converge the fuel pressure to a target fuel pressure in a fuel pressure control device for an internal combustion engine that controls the fuel pressure of a plurality of fuel pumping systems. This is to improve the controllability at the time.
[0007]
[Means for Solving the Problems]
In the following, means for achieving the above object and its effects are described.
In the invention described in claim 1, the fuel injection valve of the internal combustion engine Common accumulator piping to which A plurality of fuel pumping systems for supplying fuel to the pump, Fuel pressure detecting means for detecting an actual fuel pressure in the pressure accumulating pipe; Above Detected fruit When calculating the operation amount of each fuel pumping system to control the fuel pressure to the target fuel pressure, It is determined which of the fuel pumping systems the actual fuel pressure corresponds to fuel pumping by the fuel pumping system, and the fuel determined to correspond Control information required according to the pumping characteristics of the feed pumping system According to the control law of feedback control according to the deviation between the actual fuel pressure and the target fuel pressure These are set separately for each fuel pumping system, and based on the set control information Above Manipulated volume Respectively An operation amount calculating means for calculating is provided.
[0008]
According to such a configuration, the individual pumping characteristics in each fuel pumping system are reflected when calculating the operation amount of each fuel pumping system. As a result, even if the pumping characteristics of each fuel pumping system are different, based on the amount of operation that varies depending on the difference in such pumping characteristics. In pressure storage piping of Fruit The fuel pressure can be controlled Fruit Controllability at the time of converging the fuel pressure to the target fuel pressure can be improved.
[0009]
In addition, as the above-mentioned pumping characteristics,
・ Fuel pumping amount (fuel pumping speed) with respect to a predetermined operation amount of the fuel pumping system
・ Flow path resistance when fuel flows through the pumping path of the fuel pumping system
・ Volume of the above pumping path
・ Response of the mechanism that adjusts the fuel pumping amount of the fuel pumping system
And so on.
[0011]
Incidentally, more specific modes of the feedback control include PID control including proportional action (P), integral action (I), differential action (D), P control including only proportional action, proportional action and integration. PI control including only operation, PD control including only proportional operation and differential operation, and the like can be mentioned.
[0012]
Claim 2 In the invention described in claim 1 In the internal combustion engine fuel pressure control device described in the above, the operation amount calculation means is the Be detected A proportional term obtained by multiplying the deviation between the actual fuel pressure and the target fuel pressure by a proportional gain set for each fuel pumping system is set as the control information, and the operation is performed based on the set proportional term. The amount is to be calculated.
[0013]
According to such a configuration, among the fuel pumping systems, the fuel pumping system having a relatively high responsiveness related to the fuel pumping, by setting the proportional gain small, conversely, the fuel pumping system having a relatively low responsiveness. Even if there is a difference in responsiveness by setting a large proportional gain, Accumulation piping Inside Fruit The fuel pressure can follow the transient change in the target fuel pressure at an appropriate follow-up speed. Fruit Controllability at the time of converging the fuel pressure to the target fuel pressure can be improved.
[0014]
Claim 3 In the invention described in claim 1 Or 2 In the internal combustion engine fuel pressure control device described in the above, the operation amount calculation means is the Be detected An integral term obtained by integrating the difference between the actual fuel pressure and the target fuel pressure separately for each fuel pumping system is set as the control information, and the manipulated variable is calculated based on the set integral term. It is said that.
[0015]
According to such a configuration, since the integral term is integrated and calculated for each fuel pumping system, the difference in the pumping characteristics in each fuel pumping system, particularly if it is caused by a change over time, The difference can be reflected in the calculation of the operation amount of each fuel pumping system. Therefore, at the steady time when the target fuel pressure is kept substantially constant, Accumulation piping Inside Fruit It is possible to prevent a constant deviation from remaining between the fuel pressure and the target fuel pressure. Fruit Controllability at the time of converging the fuel pressure to the target fuel pressure can be improved.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
[First Embodiment]
Hereinafter, a first embodiment in which the present invention is applied to a control device for controlling fuel pressure in a common rail provided in a diesel engine will be described.
[0017]
FIG. 1 shows a schematic configuration of a four-cylinder direct injection diesel engine (hereinafter simply referred to as “engine”) 10 and a fuel supply apparatus thereof according to the present embodiment.
As shown in the figure, this fuel supply device includes an injector 12 provided corresponding to each cylinder # 1 to # 4 of the engine 10, a common rail 20 to which these injectors 12 are connected, and a fuel tank 14 A fuel pump 30 that pumps fuel to a common rail 20 as a pressure accumulation pipe, and an electronic control unit (hereinafter referred to as “ECU”) 60 are provided.
[0018]
The common rail 20 functions as a pressure accumulation pipe that accumulates fuel supplied from the fuel pump 30 with a predetermined pressure, and the fuel injection pressure of the injector 12 is determined based on the internal fuel pressure (rail pressure). A relief valve 22 is attached to the common rail 20, and the relief valve 22 is connected to the fuel tank 14 via a relief passage 21.
[0019]
The injector 12 is an electromagnetic valve that is opened and closed by the ECU 60, and injects fuel supplied from the common rail 20 into the combustion chambers (not shown) of the cylinders # 1 to # 4. Each injector 12 is also connected to the fuel tank 14 via a relief passage 21, and the fuel leaked into the interior of the injector 12 when the injector 12 is opened and closed is returned to the fuel tank 14 through the relief passage 21. It has become.
[0020]
The ECU 60 is for executing control related to the fuel pumping amount of the fuel pump 30, the fuel injection timing of the injector 12, and the fuel injection amount. The ECU 60 stores various control programs, function data, etc., and various calculations. The CPU 62 is configured to execute processing.
[0021]
The ECU 60 is connected to various sensors for detecting the operating state of the engine 10, the fuel state in the common rail 20, and the like, and detection signals are respectively input from these sensors.
[0022]
For example, a rotation speed sensor 65 is provided in the vicinity of the crankshaft (not shown) of the engine 10, and a cylinder discrimination sensor 66 is provided in the vicinity of the camshaft (not shown). The ECU 60 calculates the rotational speed of the crankshaft (engine rotational speed NE) and the rotational angle of the crankshaft (crank angle CA) based on the detection signals input from these sensors 65 and 66, respectively.
[0023]
An accelerator sensor 67 is provided in the vicinity of an accelerator pedal (not shown), and a detection signal corresponding to the accelerator pedal depression amount (accelerator opening ACCP) is output from the accelerator sensor 67. A fuel pressure sensor 68 is provided on the common rail 20, and a detection signal corresponding to the rail pressure (actual fuel pressure PCR) is output from the fuel pressure sensor 68. The ECU 60 detects the accelerator opening ACCP and the actual fuel pressure PCR based on the detection signals from the sensors 67 and 68, respectively.
[0024]
The fuel pump 30 is driven by a drive shaft 40 that is driven to rotate by a crankshaft of the engine 10, a feed pump 31 that operates based on the rotation of the drive shaft 40, and a pair of drives that are driven by an annular cam 42 formed on the drive shaft 40. Supply pump (first supply pump 50a and second supply pump 50b) and a pair of adjustment valves (first adjustment valve 70a and second adjustment valve 70b) for adjusting the fuel pumping amount of each of the supply pumps 50a and 50b ) Etc.
[0025]
The feed pump 31 sucks the fuel in the fuel tank 14 from the suction port 34 through the suction passage 24 and supplies the fuel to the first supply pump 50a and the second supply pump 50b with a predetermined feed pressure.
[0026]
Both the first supply pump 50a and the second supply pump 50b are so-called inner cam pumps, and pressurize the fuel supplied from the feed pump 31 to a higher pressure (for example, 25 to 180 MPa). The discharged fuel is pumped from the discharge port 38 to the common rail 20 through the discharge passage 23.
[0027]
FIG. 2 schematically shows the cross-sectional structure of each of the supply pumps 50a and 50b along the lines 2A-2A and 2B-2B in FIG. 1, and the structure of the fuel path in the fuel pump 30.
[0028]
As shown in the figure, the first supply pump 50a includes a cylindrical support portion 43 formed in the housing 41 (see FIG. 1) of the fuel pump 30, a through hole 43a formed in the support portion 43, and the like. A pair of plungers 54a supported so as to be able to reciprocate, a first pressurizing chamber 52a defined by inner end surfaces of the plungers 54a and an inner wall of the through hole 43a, and the like are provided. A shoe 55a is formed on the outer end portion of each plunger 54a, and a roller 56a is rotatably supported on each shoe 55a.
[0029]
Since the cam face 42c with which each roller 56a can come into contact with the cam 42 has an elliptical cross section, when the cam 42 rotates with the rotation of the drive shaft 40, the cam face 42c in the reciprocating direction of each plunger 54a The distance La increases and decreases with the rotation. Accordingly, when the cam 42 rotates while the rollers 56a are in contact with the cam face 42c, the plungers 54a reciprocate so as to approach and separate from each other, and the first pressurizing chamber 52a moves along with the reciprocation. Volume will increase or decrease. Hereinafter, the period during which the distance La between the cam faces 42c increases is referred to as “suction stroke” of the first supply pump 50a, and the period during which the distance La decreases as “pressure feeding stroke”.
[0030]
The drive shaft 40 has a reduction ratio with respect to the crankshaft set to ½, and rotates once every two rotations of the crankshaft. Therefore, while the crankshaft rotates twice and one cycle operation such as intake / compression / explosion / exhaust is performed in each of the cylinders # 1 to # 4, the suction stroke and the pressure stroke are alternately performed in the first supply pump 50a. It will be repeated twice.
[0031]
The first pressurizing chamber 52a is connected to the feed pump 31 via a check valve 44a and a first regulating valve 70a, and is connected to the discharge port 38 via another check valve 46a. Each of these check valves 44a and 46a feeds from the first pressurizing chamber 52a so that the fuel flow direction is always in the direction from the feed pump 31 to the common rail 20 via the first supply pump 50a. The fuel flow toward the pump 31 and the fuel flow from the discharge port 38 toward the first pressurizing chamber 52a are respectively regulated.
[0032]
The first supply pump 50a, the first regulating valve 70a, the check valves 44a and 46a, the common rail 20, the feed pump 31, and the fuel paths that connect them are configured as described above. ing.
[0033]
In the first fuel pumping system, when the first regulating valve 70a is opened during the intake stroke of the first supply pump 50a, fuel is fed from the feed pump 31 into the first pressurizing chamber 52a. 44a. All of the fuel thus supplied into the first pressurizing chamber 52a is discharged from the first pressurizing chamber 52a to the discharge port 38 via the check valve 46a in the pressure supply stroke of the first supply pump 50a. And pumped.
[0034]
On the other hand, the second supply pump 50b is also an inner cam type pump, and includes a second pressurizing chamber 52b, a plunger 54b, a shoe 55b, a roller 56b, and the like, and is configured in the same manner as the first supply pump 50a. .
[0035]
The through hole 43b that supports the plunger 54b so as to be able to reciprocate is formed so as to extend in a direction orthogonal to the direction of the through hole 43a of the first supply pump 50a. For this reason, if the period during which the distance Lb between the cam faces 42c in the reciprocating direction of each plunger 54b increases is the “suction stroke” of the second supply pump 50b, and the period during which the distance Lb decreases is the “pressure feed stroke”, The suction stroke and the pumping stroke of the second supply pump 50b are in a state in which the phase is shifted by 180 ° CA (CA: Crank Angle) as the crank angle CA with respect to the suction stroke and the pumping stroke of the first supply pump 50a. It has become.
[0036]
The second pressurizing chamber 52b has a configuration similar to that of the first pressurizing chamber 52a, and is connected to the feed pump 31 via the check valve 44b and the second regulating valve 70b, and another reverse chamber. It is connected to the discharge port 38 via the stop valve 46b.
[0037]
The second supply pump 50b, the second regulating valve 70b, the check valves 44b and 46b, the common rail 20, the feed pump 31, and the fuel paths that connect them together constitute the second fuel pumping system described above. ing.
[0038]
The feed pump 31 is connected to the relief valve 32 in addition to the regulating valves 70a and 70b. The relief valve 32 is further connected to the fuel tank 14 through a relief port 36 by a relief passage 21 (see FIG. 1). When the regulating valves 70a and 70b are closed in the intake stroke of the supply pumps 50a and 50b, the relief valve 32 is opened by the pressure of the fuel discharged from the feed pump 31, and the fuel is It is returned to the fuel tank 14 through the relief passage 21.
[0039]
The ECU 60 sets the opening timing of each of the regulating valves 70a and 70b to the start timing of the suction stroke, and changes the valve closing timing during the suction stroke to thereby suck the fuel sucked into the pressurizing chambers 52a and 52b. Adjust the amount. By adjusting the fuel intake amount in this way, the fuel pumping amount of each of the supply pumps 50a and 50b, and hence the fuel pumping pressure, is controlled.
[0040]
For example, the ECU 60 increases the fuel suction period of each of the supply pumps 50a and 50b by delaying (retarding) the closing timing of each of the adjustment valves 70a and 70b, thereby increasing the fuel pumping amount of each of the supply pumps 50a and 50b. By advancing (advancing) the valve closing timing, the fuel intake period is reduced, and the fuel pumping amount of each of the supply pumps 50a and 50b is reduced.
[0041]
Incidentally, the valve opening timing and the valve closing timing of each of the regulating valves 70a and 70b are both defined with the crank angle as a unit, and the valve closing timing is a relative crank angle based on the valve opening timing. Is set. Therefore, for example, when stopping the fuel pumping by the supply pumps 50a and 50b, the valve closing timing is set to “0 ° CA”, and the regulating valves 70a and 70b are always kept closed during the intake stroke. Become so. On the other hand, when the fuel pumping amount is set to the maximum, the valve closing timing is set to “180 ° CA” corresponding to the crank angle change amount during the intake stroke, and the adjusting valves 70a and 70b are always set during the intake stroke. The valve is held open.
[0042]
FIG. 3 shows a change state of the rail pressure in a steady state in which the target value of the rail pressure (target fuel pressure PCTRG) is maintained substantially constant, fuel pumping / suctioning operation timings of the supply pumps 50a and 50b, and the like. Is a timing chart showing the crank angle corresponding to the crank angle CA.
[0043]
As shown in FIG. 6A, even in such a steady state, the rail pressure is maintained by the fuel pumping by the supply pumps 50a and 50b (FIG. 5B and FIG. 5C) and the fuel injection by the injectors 12 (same as above). It always fluctuates according to the figure (d)). Incidentally, the reason that the rail pressure slightly decreases even when neither fuel pumping nor fuel injection is performed is that a small amount of fuel is always returned from the injectors 12 to the fuel tank 14 through the relief passage 21. .
[0044]
The fuel pumping by the supply pumps 50a and 50b and the fuel injection by the injectors 12 are executed while maintaining a predetermined relationship with respect to the crank angle CA. For example, in a period where the crank angle CA is [CA1 to CA2], fuel injection by the injector 12 corresponding to the first cylinder # 1 and fuel pumping by the second supply pump 50b are performed, and the crank angle CA is set to [CA2 to CA2]. During the period of CA3], fuel injection in the third cylinder # 3 and fuel pumping by the first supply pump 50a are performed.
[0045]
FIG. 6E shows the detection timing of the actual fuel pressure PCR by the ECU 60. As shown in FIG. 5E, the actual fuel pressure PCR is detected at every predetermined crank angle (every 180 ° CA), and the detection timing is the rail pressure by the fuel pumping of each supply pump 50a, 50b. Is set at the time when the increase of (1), (CA1, CA2, CA3, CA4) ends.
[0046]
Further, FIG. 5F shows how the determination counter value CPCYLND changes. This determination counter value CPCYLND is a counter value used in processing for calculating the operation amount of each supply pump 50a, 50b, that is, the valve closing timing of each adjustment valve 70a, 70b. In the counter value operation routine, [. [0 → 1 → 2 → 3 → 0 →...]] And incremented by 1 every predetermined crank angle (every 180 ° CA).
[0047]
Also, based on the value of the determination counter value CPCYLND, it can be determined which of the first supply pump 50a and the second supply pump 50b the actual fuel pressure PCR corresponds to.
[0048]
That is, as shown in the figure, when the determination counter value CPCYLND at the time of detection of the actual fuel pressure PCR is set to “1” or “3”, the actual fuel pressure PCR is determined as the fuel of the first supply pump 50a. When the judgment counter value CPCYLND is set to “0” or “2”, on the other hand, the actual fuel pressure PCR corresponds to the magnitude of the rail pressure after increasing by the pressure feeding, and the actual fuel pressure PCR is the fuel of the second supply pump 50b. It can be determined that this corresponds to the magnitude of the rail pressure after rising by pressure feeding.
[0049]
Next, fuel pressure control according to this embodiment will be described. In this fuel pressure control, the valve closing timing (final valve closing timing ANGFIN) of each of the regulating valves 70a, 70b is calculated, and the fuel intake amount in each of the supply pumps 50a, 50b is increased or decreased based on the final valve closing timing ANGFIN. Thus, feedback control is performed so that the pressure of the fuel pumped from each of the supply pumps 50a and 50b matches the target value (target fuel pressure PCRTRG).
[0050]
Hereinafter, the fuel pressure control procedure will be described in detail with reference to the flowcharts shown in FIGS. 4 and 5. The “fuel pressure control routine” shown in these flowcharts is executed by the ECU 60 as an interrupt process for every predetermined crank angle (every 180 ° CA).
[0051]
The actual fuel pressure PCR is detected as a part of this “fuel pressure control routine”. In other words, the interrupt timing of the “fuel pressure control routine” is the timing at which the rise of the rail pressure due to the fuel pumping of the supply pumps 50a and 50b ends as already described as the detection timing of the actual fuel pressure PCR (see FIG. 3). CA1, CA2, CA3, CA4 shown).
[0052]
When this “fuel pressure control routine” is started, the ECU 60 detects the actual fuel pressure PCR in step 110, and then calculates the target fuel pressure PCRTRG based on the fuel injection amount and the engine speed NE in step 120.
[0053]
The relationship between the target fuel pressure PCRTRG, the fuel injection amount, and the engine rotational speed NE is obtained in advance by experiments so that the spray particle size of the injected fuel is adapted to the engine combustion state, and is stored in the memory 64 of the ECU 60. It is stored as function data for calculating the fuel pressure PCRTRG.
[0054]
The fuel injection amount is a value that is calculated based on the accelerator opening ACCP, the engine speed NE, and the like and stored in the memory 64 in a routine different from this routine.
[0055]
Next, in step 130, the ECU 60 calculates a basic valve closing timing ANGBASE based on the fuel injection amount, the actual fuel pressure PCR, and the engine speed NE. This basic valve closing timing ANGBASE is required for each supply pump required during steady operation of the fuel pump 30, that is, when the rail pressure is substantially equal to the target fuel pressure PCRTRG and the target fuel pressure PCRTRG is held substantially constant. It is determined based on the fuel pumping amounts 50a and 50b. The relationship between the basic valve closing timing ANGBASE and the fuel injection amount is stored in advance in the memory 64 as function data for calculating the basic valve closing timing ANGBASE.
[0056]
In step 140, the actual fuel pressure PCR is subtracted from the target fuel pressure PCRTRG, and the subtraction value (PCRTRG-PCR) is set as a deviation ΔPCR. In step 150, the proportional term ANGPRO is calculated based on the following equation (1).
[0057]
ANGPRO = Kp · ΔPCR (1)
This proportional term ANGPRO performs a proportional operation in so-called PID control (in particular, here, PI control), and is a correction angle for correcting the basic valve closing timing ANGBASE according to the magnitude of the deviation ΔPCR. “Kp” is a proportional gain, and is set based on an average pumping characteristic of each fuel pumping system.
[0058]
Next, in step 160, it is determined whether or not an update prohibition condition for the integral term ANGINT is satisfied. The integral term ANGINT performs an integral operation in PID control, and is a correction angle for correcting the basic valve closing timing ANGBASE according to the magnitude of the deviation ΔPCR.
[0059]
In step 160, the previous value ANGFINO of the final valve closing timing ANGFIN is “180 ° CA” which is the maximum value or “0 ° CA” which is the minimum value, in other words, the rail pressure. Is in a transitional state as the update prohibition condition. That is, the integral term ANGINT is for canceling out the steady deviation remaining between the rail pressure and the target fuel pressure PCRTRG when the rail pressure becomes substantially equal to the target fuel pressure PCRTRG. When the final valve closing timing ANGFIN is set to “180 ° CA” or “0 ° CA” and the rail pressure suddenly increases or decreases, updating of the integral term ANGINT is prohibited.
[0060]
If the ECU 60 determines that such an update prohibition condition is satisfied, the ECU 60 sets the update amount DANGINT to “0 ° CA” in step 180. On the other hand, if it is determined that the update prohibition condition is not satisfied, the process proceeds to step 170, and the update amount DANGINT is calculated based on the following equation (2).
[0061]
DANGINT = Ki · | ΔPCR | (2)
Here, “Ki” is an integral gain (integration time), and “| ΔPCR |” is an absolute value of the deviation ΔPCR.
[0062]
After the update amount DANGINT is set in each of steps 170 and 180, in step 200, an integral term ANGINT is calculated based on the update amount DANGINT.
[0063]
Hereinafter, a detailed calculation procedure of the integral term ANGINT will be described with reference to the flowchart of FIG.
When calculating the integral term ANGINT, corresponding integral term ANGINT values ANGINT1 and ANGINT2 are prepared for each fuel pumping system, and these values ANGINT1 and ANGINT2 are synchronized with the fuel pumping operation of each fuel pumping system, respectively. It is updated and stored in the memory 64.
[0064]
First, in step 202, the ECU 60 determines whether the above-described determination counter value CPCYLND is “0” or “2”, that is, the final valve closing timing ANGFIN calculated this time is the second fuel pumping system (second supply system). It is determined whether or not it is for operating the second regulating valve 70b) of the pump 50b.
[0065]
If it is determined that the determination counter value CPCYLND is “0” or “2”, the integral term ANGINT is set to correspond to the second fuel pumping system in steps 210 to 214.
[0066]
First, the ECU 60 determines in step 210 whether or not the deviation ΔPCR is larger than “0”, that is, whether or not the target fuel pressure PCRTRG is higher than the actual fuel pressure PCR.
[0067]
If it is determined that the target fuel pressure PCRTRG exceeds the actual fuel pressure PCR, the integral term ANGINT2 (integral term ANGINT2) of the integral term ANGINT corresponding to the second fuel pumping system is read from the memory 64 in step 212, and A value obtained by adding the update amount DANGINT to the integral term ANGINT2 (ANGINT2 + DANGINT) is updated as a new integral term ANGINT2, and stored in the memory 64 again.
[0068]
On the other hand, if it is determined that the target fuel pressure PCRTRG is less than or equal to the actual fuel pressure PCR, a value obtained by subtracting the update amount DANGINT from the value ANGINT2 of the integral term ANGINT (ANGINT2-DANGINT) is updated as a new integral term ANGINT2 in Step 213. And stored in the memory 64.
[0069]
Incidentally, when the previous update prohibition condition is satisfied, the update amount DANGINT is set to “0 ° CA”, so that the update of the integral term ANGINT2 in each of the above steps 212 and 213 is not substantially executed. It will be.
[0070]
By executing the processing of these steps 212 and 213, the integral term ANGINT2 is integrated and calculated based on the deviation ΔPCR caused by the fuel pumping of the second fuel pumping system.
[0071]
In step 214, the integral term ANGINT2 corresponding to the second fuel pumping system thus updated is set as the final integral term ANGINT.
On the other hand, when determining that the determination counter value CPCYLND is “1” or “3” in the previous step 202, the ECU 60 performs the first step 220 to 224 in the first step 220 to 224 in the same manner as the above-described steps 210 to 214. The integral value ANGINT1 ANGINT1 corresponding to the fuel pumping system is integrated and set as the final integral term ANGINT.
[0072]
After the integral term ANGINT is set so as to correspond to each fuel pumping system in this way, in step 240, the finally set integral term ANGINT and the integral term ANGINT1 for each fuel pumping system stored in the memory 64 are stored. , ANGINT2 is determined to be within a predetermined angle range.
[0073]
Here, if it is determined that any one of the integral terms ANGINT, ANGINT1, and ANGINT2 is greater than a predetermined upper limit angle or less than a predetermined lower limit angle, in step 242, an integral term outside the predetermined angle range is determined. ANGINT, ANGINT1, and ANGINT2 are corrected to be equal to the upper limit angle or the lower limit angle.
[0074]
Thus, by limiting the magnitudes of the integral terms ANGINT, ANGINT1, and ANGINT2 within a predetermined angle range, these integral terms ANGINT, ANGINT1, and ANGINT2 are temporarily set excessively, and the integral terms ANGINT, ANGINT1, and ANGINT2 are It becomes possible to suppress the state that does not correspond to the current steady-state deviation from continuing for a long period of time.
[0075]
After correcting the integral terms ANGINT, ANGINT1, and ANGINT2 in this way, or when it is determined in step 240 that correction is not necessary, the process proceeds to step 300 shown in FIG.
[0076]
In step 300, the basic valve closing timing ANGBASE, the proportional term ANGPRO, and the integral term ANGINT are added, and the added value (ANGBASE + ANGPRO + ANGINT) is set as the final valve closing timing ANGFIN. In the subsequent step 302, the current final valve closing timing ANGFIN is set as the previous value ANGFINO, and then a series of processing is temporarily ended.
[0077]
In another processing routine, the ECU 60 generates a drive signal based on the final valve closing timing ANGFIN, and alternately outputs the drive signal to the regulating valves 70a and 70b. For example, when the final valve closing timing ANGFIN is calculated at timings CA1 and CA3 shown in FIG. 3, a drive signal based on the final valve closing timing ANGFIN is output to the first adjustment valve 70a, and at timings CA2 and CA4. When the final valve closing timing ANGFIN is calculated, a drive signal is output to the second regulating valve 70b. As a result, the rail pressure is controlled to coincide with the target fuel pressure PCRTRG.
[0078]
Here, in the fuel pressure control, the integral term ANGINT is updated separately for each fuel pumping system, and the final valve closing timing ANGFIN is based on the values ANGINT1, ANGINT2 of the integral terms ANGINT corresponding to these fuel pumping systems. To calculate.
[0079]
Therefore, even when the pumping characteristic of any one of the fuel pumping systems changes with time and the steady deviation between the actual fuel pressure PCR and the target fuel pressure PCRTRG increases, the fuel pumping system whose pumping characteristics have changed. Only the values ANGINT1, ANGINT2 of the integral term ANGINT corresponding to are updated according to the increased steady-state deviation.
[0080]
Incidentally, the main factors that change the pumping characteristics of each fuel pumping system over time include, for example, an increase in sliding resistance between the plungers 54a and 54b of the supply pumps 50a and 50b and the inner walls of the through holes 43a and 43b. The response speed of the regulating valves 70a and 70b can be reduced, that is, the response delay time from when the valve closing drive signal is input until the regulating valves 70a and 70b are closed can be exemplified.
[0081]
When fuel is supplied to the pressurizing chambers 52a and 52b of the supply pumps 50a and 50b in the intake stroke, the plungers 54a and 54b are moved to the cam face 42c side by the supply pressure, and the pressurizing chambers 52a and 52b are moved. Increase in volume. However, when the sliding resistance between the inner walls of the plungers 54a, 54b and the through holes 43a, 43b increases as described above, the plungers 54a, 54b become difficult to move, corresponding to the opening periods of the adjusting valves 70a, 70b. The pumping stroke is started without the amount of fuel being sucked. Therefore, the increase in the sliding resistance decreases the fuel pumping amount from each fuel pumping system.
[0082]
Further, when the response delay time in each of the regulating valves 70a and 70b is increased, the pressurizing chambers 52a and 52b are supplied by an amount corresponding to the response delay time even after the valve closing drive signal is output to each of the regulating valves 70a and 70b. Extra fuel will be inhaled. Therefore, the increase in the response delay time increases the amount of fuel pumped from each fuel pumping system.
[0083]
FIG. 6 (a) shows that the actual fuel pressure PCR after the completion of the pumping of the pump 50a in a steady state is reduced due to the decrease in the pumping capacity of the first fuel pumping system due to, for example, an increase in the sliding resistance as described above. The change mode of the rail pressure when the fuel pressure is always lower than the target fuel pressure PCRTRG is shown.
[0084]
In such a case, if the integral term ANGINT is updated in common without distinction for each fuel pumping system, as shown in FIG. 5B, after the fuel pumping by the first fuel pumping system is completed. Although the deviation ΔPCR1 between the actual fuel pressure PCR and the target fuel pressure PCRTRG decreases, conversely, the actual fuel pressure PCR after the completion of the fuel pumping by the second fuel pumping system always exceeds the target fuel pressure PCRTRG. The fuel pressure of the second fuel pumping system is controlled. As a result, fluctuations in the rail pressure during fuel injection cannot be avoided, and the fuel injection amount may vary for each cylinder # 1 to # 4, or the exhaust properties may deteriorate.
[0085]
In this respect, according to the fuel pressure control according to the present embodiment, even in such a case, the integral term ANGINT is updated separately for each fuel pumping system, and therefore, the operation amount (final amount) for the first fuel pumping system in which the pumping capacity is reduced is determined. Only the valve closing timing ANGFIN) increases as the integral term ANGINT is updated. Therefore, as shown in FIG. 6C, only the fuel pressure of the first fuel pumping system matches the target fuel pressure PCRTRG without adversely affecting the fuel pumping of the second fuel pumping system. It is possible to control the above-described variations in the fuel injection amount and the deterioration of exhaust properties.
[0086]
Incidentally, even if the fuel pumping amount of either fuel pumping system becomes excessive due to the increase in the response delay time, the above-mentioned variation in the fuel injection amount and deterioration of the exhaust properties occur similarly. However, according to the fuel pressure control according to the present embodiment, occurrence of these problems can be similarly suppressed even in such a case.
[0087]
Thus, according to the present embodiment, the difference in the pumping characteristics in each fuel pumping system can be reflected when calculating the operation amount (final valve closing timing ANGFIN). Accordingly, it is possible to reliably prevent a steady deviation from remaining between the rail pressure and the target fuel pressure, and to improve controllability when the rail pressure is converged to the target fuel pressure.
[0088]
[Second Embodiment]
Next, a second embodiment of the present invention will be described focusing on differences from the first embodiment. Note that the description of the same configuration as in the first embodiment is omitted.
[0089]
In the fuel pressure control in the present embodiment, the proportional term ANGPRO is calculated by switching the proportional gain Kp for each fuel pumping system in addition to updating the integral term ANGINT for each fuel pumping system. I have to.
[0090]
Hereinafter, the calculation procedure of the proportional term ANGPRO will be described with reference to FIG. FIG. 7 shows the details of the processing in step 150 of the flowchart shown in FIG.
[0091]
After calculating the deviation ΔPCR in step 140 shown in FIG. 2, the ECU 60 proceeds to step 152 in FIG. In step 152, it is determined whether or not the determination counter value CPCYLND is “0” or “2”, that is, whether or not the final valve closing timing ANGFIN calculated this time is for operating the second fuel pumping system. To do.
[0092]
If it is determined that the determination counter value CPCYLND is “0” or “2”, the proportional gain Kp is set to a value Kp2 corresponding to the second fuel pumping system in step 154. On the other hand, if it is determined that the determination counter value CPCYLND is “1” or “3”, in step 155, the proportional gain Kp is set to a value Kp1 corresponding to the first fuel pumping system.
[0093]
These values Kp1 and Kp2 are set in advance by experiments or the like based on the pumping characteristics of each fuel pumping system.
Incidentally, as the pumping characteristic here, the fuel pumping amount of each supply pump 50a, 50b with respect to a predetermined final closing timing ANGFIN, the common rail 20 and the fuel path from each supply pump 50a, 50b to the common rail 20 The total volume of the part, the flow path resistance of each fuel path, etc. can be mentioned. For example, when the responsiveness related to the fuel pumping of each fuel pumping system is low, such as when the fuel pumping amount is relatively small or when the volume or flow path resistance is relatively large, the proportional gain Kp The values Kp1 and Kp2 are set relatively large. Therefore, when the responsiveness in each fuel pumping system is different, these values Kp1 and Kp2 are set to different sizes according to the difference in responsiveness.
[0094]
After setting the proportional gain Kp in this way, the ECU 60 calculates a proportional term ANGPRO in step 156 based on the above equation (1). Then, the final valve closing timing ANGFIN is calculated based on the proportional term ANGPRO by executing the processing from step 160 shown in FIG.
[0095]
According to the fuel pressure control of the present embodiment described above, the rail corresponding to the predetermined operation amount (final valve closing timing ANGFIN) even if there is a difference in the responsiveness related to the fuel pumping of each fuel pumping system. The amount of pressure increase is substantially equal in each fuel pumping system. Therefore, the rail pressure can be made to follow a transient change in the target fuel pressure at an appropriate follow-up speed, and the controllability when the rail pressure is converged to the target fuel pressure can be improved. become.
[0096]
Further, if the follow-up speed is different for each fuel pumping system, the rail pressure may be pulsated due to fluctuations in the follow-up speed. When such pulsation of rail pressure occurs, not only at the time of steady state as described above but also at the time of transition, variations in fuel injection amount and deterioration of exhaust properties are caused.
[0097]
In this respect, according to the present embodiment, the rail pressure can be made to follow the change in the target fuel pressure at a substantially constant follow-up speed, so that the occurrence of such pulsation can be suppressed, as described above. This makes it possible to suppress variations in fuel injection amount and deterioration of exhaust properties.
[0098]
[Other Embodiments]
Each embodiment described above can be implemented by changing the configuration as follows.
[0099]
In each of the above embodiments, the abnormality of each fuel pumping system can be detected based on the magnitudes of the integral terms ANGINT1 and ANGINT2 that are updated separately for each of the supply pumps 50a and 50b.
[0100]
When such abnormality detection is performed, each process shown in the flowchart of FIG. 8 is executed after the processes of steps 214 and 224 of FIG. 5 and before the processes of step 240 and subsequent steps.
[0101]
That is, as shown in the figure, in step 230, the absolute value | ANGINT1-ANGINT2 | of deviations of the integral terms ANGINT and ANGINT1 and ANGINT2 is set as the abnormality determination deviation ΔK. This abnormality determination deviation ΔK is used to determine whether an abnormality has occurred in either one of the fuel pumping systems. If any one of the fuel pumping systems is normally performing fuel pumping. If not, only one of the values ANGINT1, ANGINT2 of the integral term ANGINT increases, so that this abnormality determination deviation ΔK also increases.
[0102]
Next, in step 232, it is determined whether or not the abnormality determination deviation ΔK is larger than a predetermined determination value ΔK1. If the abnormality determination deviation ΔK is larger than the determination value ΔK1, it is determined that an abnormality has occurred in one of the fuel pumping systems. In step 234, an abnormality detection flag XPUMP indicating the abnormality is set. Set to “ON”.
[0103]
Incidentally, the abnormalities of each fuel pumping system detected here include the engagement of the plungers 54a and 54b due to the excessive increase of the sliding resistance described above, the malfunction of the regulating valves 70a and 70b, Fuel leaks, etc.
[0104]
After executing the processing of step 234, or if it is determined in step 232 that the abnormality determination deviation ΔK is equal to or less than the determination value ΔK1, and fuel pumping by each fuel pumping system is normally performed Also, the processing after step 240 shown in FIG. 5 is executed.
[0105]
For example, when an abnormality occurs in only one of the fuel pumping systems and the pumping capacity decreases, the deviation between the rail pressure and the target fuel pressure caused by the decrease in the pumping capacity is canceled out. The fuel pumping amount of the other supply pumps 50a and 50b is increased by feedback control. Therefore, in the configuration in which an abnormality is detected based on the magnitude of the integral term ANGINT that is updated in common without particular distinction for each fuel pumping system, the change width of the integral term ANGINT becomes small and the abnormality is reduced. It cannot be detected or the detection is delayed.
[0106]
In this regard, according to the above configuration, even when an abnormality occurs in only one of the fuel pumping systems, the abnormality can be reliably and early detected.
Further, as yet another mode for detecting such abnormality of each fuel pumping system, the absolute values | ANGINT1 |, | ANGINT2 | of the integral term ANGINT values ANGINT1, ANGINT2 are respectively compared with predetermined judgment values. Based on the fact that the absolute values | ANGINT1 | and | ANGINT2 | exceeded the judgment value, in other words, the values ANGINT1 and ANGINT2 of the integral term ANGINT were out of the predetermined range centered on “0”. You may make it detect abnormality of each fuel pumping system separately.
[0107]
According to such an abnormality detection procedure, it is possible to identify each fuel pumping system in which an abnormality has occurred, and it is also possible to perform more accurate measures in response to the abnormality.
In each of the above embodiments, in addition to the integral term ANGINT or the proportional term ANGPRO, the basic valve closing timing ANGBASE may be similarly set for each fuel pumping system.
[0108]
In the second embodiment, only the proportional term ANGPRO can be set for each fuel pumping system, and the integral term ANGINT can be set commonly for both fuel pumping systems.
[0109]
In each of the above embodiments, as a feedback control term for calculating the final closing timing ANGFIN, in addition to the proportional term ANGPRO and the integral term ANGINT, the differential value of the deviation ΔPCR is further multiplied by a predetermined gain. It is also possible to use a differential term. Further, in this case, this differential term may be set separately for each fuel pumping system.
[0110]
In each of the above embodiments, the fuel supply device including two fuel pumping systems has been described as an example. However, the present invention can be similarly applied to a fuel supply device including three or more fuel pumping systems. .
[0111]
In each of the above embodiments, the diesel engine is exemplified as the internal combustion engine to which the fuel pressure control device according to the present invention is applied. For example, the fuel pressure according to the present invention is applied to a direct injection gasoline engine that directly injects fuel into the combustion chamber. A control device can also be applied.
[0112]
The technical ideas that can be grasped from each of the above embodiments will be described below together with the effects.
(A) a plurality of fuel pumping systems for supplying fuel to a fuel injection valve of an internal combustion engine;
When calculating the operation amount of each fuel pumping system according to the control rule of feedback control in order to control the fuel pressure in each fuel pumping system to the target fuel pressure, the fuel pressure in each fuel pumping system and the target fuel pressure are calculated. And an operation amount calculating means for calculating the operation amount based on the set integral term;
An abnormality detecting means for detecting an abnormality of each fuel pumping system based on the size of the integral term for each fuel pumping system set;
A control device for an internal combustion engine, comprising:
[0113]
(B) In the control device for an internal combustion engine described in (a) above,
The abnormality detection means compares the magnitude of the integral term for each fuel pumping system, and detects an abnormality in each fuel pumping system based on the comparison result.
A control device for an internal combustion engine.
[0114]
(C) In the control device for an internal combustion engine described in (a) above,
The abnormality detection means compares an integral term for each fuel pumping system with a predetermined determination value, and detects an abnormality of each fuel pumping system based on the comparison result.
A control device for an internal combustion engine.
[0115]
According to each of the above-described configurations, when each fuel pumping system is normal, the difference in pumping characteristics in each fuel pumping system, in particular, the difference caused by the change with time, This can be reflected in the calculation of the operation amount of the system. Therefore, in a steady state where the target fuel pressure is kept substantially constant, it is possible to reliably suppress a stationary deviation from remaining between the fuel pressure in each fuel pumping system and the target fuel pressure, Controllability at the time of converging the fuel pressure to the target fuel pressure can be improved.
[0116]
Furthermore, because each fuel pumping system detects an abnormality in each fuel pumping system based on an integral term calculated separately for each fuel pumping system, even if an abnormality occurs only in any one of the fuel pumping systems, The abnormality can be reliably and early detected. In particular, in the configuration described in (d) above, the fuel pumping system in which an abnormality has occurred can be identified, and appropriate measures can be taken in response to the abnormality.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram showing a fuel supply system of a diesel engine.
FIG. 2 is an explanatory diagram for explaining a cross-sectional structure of each supply pump and a structure of a fuel path in the fuel pump.
FIG. 3 is a timing chart showing how rail pressure changes in a steady state.
FIG. 4 is a flowchart showing a fuel pressure control procedure in the first embodiment.
FIG. 5 is a flowchart showing a fuel pressure control procedure in the first embodiment.
FIG. 6 is a timing chart showing how rail pressure changes in a steady state.
FIG. 7 is a flowchart showing a procedure for calculating a proportional term of fuel pressure control in the second embodiment.
FIG. 8 is a flowchart showing an abnormality detection procedure of a fuel pumping system in another embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Engine, 12 ... Injector, 14 ... Fuel tank, 16 ... Crankshaft, 18 ... Camshaft, 20 ... Common rail, 21 ... Relief passage, 22 ... Relief valve, 23 ... Discharge passage, 24 ... Suction passage, 30 ... Fuel Pump, 31 ... feed pump, 32 ... relief valve, 34 ... suction port, 36 ... relief port, 38 ... discharge port, 40 ... drive shaft, 42 ... cam, 41 ... housing, 42c ... cam face, 43 ... support, 43a ... through hole, 43b ... through hole, 44a ... check valve, 44b ... check valve, 46a ... check valve, 46b ... check valve, 50a ... first supply pump, 50b ... second supply pump, 52a ... first pressurizing chamber, 52b ... second pressurizing chamber, 54a, 54b ... plunger, 55a, 55b ... shoe, 56a, 56 ... Roller, 60 ... ECU, 62 ... CPU, 64 ... Memory, 65 ... Rotation speed sensor, 66 ... Cylinder discrimination sensor, 67 ... Accelerator sensor, 68 ... Fuel pressure sensor, 70a ... First adjustment valve, 70b ... Second tuning valve.

Claims (3)

A plurality of fuel pumping systems for pumping fuel to a common pressure accumulating pipe to which a fuel injection valve of the internal combustion engine is connected ;
Fuel pressure detecting means for detecting an actual fuel pressure in the pressure accumulating pipe;
When calculating the operation amount of each fuel pumping system in order to control the detected actual fuel pressure to the target fuel pressure, the actual fuel pressure is used for fuel pumping by any of the fuel pumping systems. to determine whether those which correspond, in the feedback control in accordance with the deviation between the corresponding the the determined fuel pumping system the actual fuel pressure control information required in accordance with the pumping characteristics of the target fuel pressure control law accordance set individually for each their respective fuel pumping systems, fuel pressure control apparatus for an internal combustion engine, characterized in that it comprises an operation amount calculating means for calculating each said operating amount based on the control information the setting. The fuel pressure control apparatus for an internal combustion engine according to claim 1,
The manipulated variable calculating means sets, as the control information, a proportional term obtained by multiplying a deviation between the detected actual fuel pressure and the target fuel pressure by a proportional gain set separately for each fuel pumping system, Calculate the manipulated variable based on the set proportional term
Fuel pressure control apparatus for an internal combustion engine, wherein a call. The fuel pressure control device for an internal combustion engine according to claim 1 or 2,
The manipulated variable calculating means sets, as the control information, an integral term obtained by integrating the difference between the detected actual fuel pressure and the target fuel pressure separately for each fuel pumping system, and the set integral term fuel pressure control apparatus for an internal combustion engine according to claim <br/> to calculate the operation amount based on.

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