JP4193302B2 - Accumulated fuel injection system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a pressure accumulation type fuel injection device that injects high pressure fuel stored in a pressure accumulation chamber from a fuel injection valve to a diesel engine, and more particularly to a fuel system abnormality detection method.
[0002]
[Prior art]
A conventionally known pressure accumulation type fuel injection device stores fuel pumped from a fuel supply pump in a pressure accumulation chamber in a high pressure state, and injects high pressure fuel in the pressure accumulation chamber from a fuel injection valve attached to each cylinder of a diesel engine. System. In this system, the amount of fuel discharged from the fuel supply pump is feedback controlled so that the fuel pressure in the pressure accumulating chamber becomes a target value. Therefore, for example, even if a fuel leak occurs in the fuel system and the fuel pressure in the pressure accumulating chamber decreases, the fuel discharge amount of the fuel supply pump increases to maintain the fuel pressure in the pressure accumulating chamber at the target value. There is a problem that leakage continues.
[0003]
Therefore, as a prior art provided with an abnormality detection means for detecting an abnormality such as fuel leakage, there is a fuel injection device for an internal combustion engine disclosed in Japanese Patent Laid-Open No. 10-299557.
In this fuel injection device, the difference between the estimated value of the fuel pressure fluctuation in the accumulator chamber before and after fuel injection from the fuel injection valve and the measured value, or the estimated value of the fuel pressure fluctuation in the accumulator chamber before and after fuel pumping from the fuel supply pump The abnormality of the fuel injection system can be detected based on the deviation between the measured value and the measured value.
[0004]
[Problems to be solved by the invention]
However, in order to detect a fuel leak by the above-described abnormality detection means, it is necessary that the fuel injection timing from the fuel injection valve and the fuel pumping timing from the fuel supply pump do not overlap. In other words, when the timings of fuel injection and fuel pumping overlap or are close to each other, for example, when detecting an abnormality based on the deviation between the estimated value of fuel pressure fluctuation in the accumulator chamber before and after fuel injection and the measured value Since the pressure in the pressure accumulating chamber largely fluctuates due to the effect of pumping by the fuel supply pump, fuel leakage cannot be determined accurately.
[0005]
For this reason, the above-described abnormality detection means has a small number of engine cylinders (number of injections) and is equal to the number of pumping pumps. For example, in the case of a four-injection / 4-pumping system, once per fuel pumping. However, when the number of engine cylinders is large or when the number of engine cylinders and the number of pump pumping are different, for example, 6 injection / 4 In the pumping system, since fuel injection is performed 1.5 times for one fuel pumping, the fuel injection timing and the fuel pumping timing may overlap.
Thus, the above-described abnormality detection means has a problem that it can be applied only to a specific engine because of the relationship between the number of engine cylinders and the number of pumping operations.
The present invention has been made based on the above circumstances, and its object is to perform abnormality determination such as fuel leakage on various engines without being influenced by the number of engine cylinders (number of injections) and the number of pumping pumps. An object of the present invention is to provide an accumulator type fuel injection device that can perform this.
[0006]
[Means for Solving the Problems]
(Means of Claim 1)
The number of times of pumping and the number of times of injection determined by an integral value of the number of times of pumping of the fuel supply pump and the number of times of injection of the fuel injection valve performed during one combustion stroke of the internal combustion engine, or a value obtained by multiplying that divisor value by an integer is 1 A section set as a group is set as a determination period, and the abnormality presence / absence determination means determines whether there is an abnormality in the fuel system in the determination period.
In this configuration, since the discharge amount from the fuel supply pump and the injection amount from the fuel injection valve included in the determination period are determined as one group to determine whether or not there is an abnormality, even when the fuel injection timing and the fuel pumping timing overlap. Thus, the presence or absence of abnormality in the fuel system can be determined more accurately.
The fuel system is the entire fuel flow path and includes a fuel supply pump, a pressure accumulating chamber, a fuel injection valve, and a fuel pipe.
[0007]
Also, When the sum of the target injection amount, the leak amount, and the pressure change equivalent amount included in the determination period is defined as the released fuel amount, the abnormality presence / absence determining means includes the total discharge amount included in the determination period, the discharged fuel amount, The presence or absence of abnormality of the fuel system is determined based on the balance of the balance. In this case, if the balance between the total discharge amount included in the determination period and the amount of released fuel is balanced, it can be determined that there is no abnormality, and the sum of the discharge amount included in the determination period and the amount of released fuel If the balance is broken, it can be determined that there is an abnormality such as fuel leakage.
[0008]
(Claims 2 Means)
Claim 1 In the described accumulator fuel injector,
When the abnormality presence / absence determining means determines that there is an abnormality, a pump control means for performing a pump discharge amount limiting operation for limiting the discharge amount of the fuel supply pump, and a pressure accumulating chamber during the pump discharge amount limiting operation Fuel leakage determination means for calculating the amount of fuel released and determining whether or not fuel leakage has occurred in the fuel system based on the calculated fuel amount;
The number of times of pumping and the number of times of injection determined by an integral value of the number of times of pumping of the fuel supply pump and the number of times of injection of the fuel injection valve performed during one combustion stroke of the internal combustion engine, or a value obtained by multiplying that divisor value by an integer A section set as a group is set as a pump control period, and the pump control means limits the discharge amount of the fuel supply pump within the pump control period.
In this case, it is possible to determine whether or not the cause of the abnormality that has occurred is related to the fuel supply pump by limiting the discharge amount of the fuel supply pump.
[0009]
(Claims 3 Means)
Claim 2 In the accumulator fuel injection device described in
The fuel leakage determination means compares the fuel amount (calculated fuel amount) discharged from the pressure accumulating chamber with the determination value during the pump discharge amount limiting operation, and when the calculated fuel amount is larger than the determination value, the fuel system It is determined that fuel leakage has occurred.
In the case where fuel leakage has occurred in the fuel system and in the case where fuel leakage has not occurred (normal case), the amount of fuel released from the pressure accumulating chamber during the pump discharge amount limiting operation is reduced. For example, if a determination value is set with reference to the amount of fuel released from the pressure accumulating chamber during normal operation and the calculated fuel amount is larger than the determination value, it can be determined that fuel leakage has occurred.
[0010]
(Claims 4, 5 Means)
Burning Feed pump Pumping timing , And the injection timing of the fuel injection valve is synchronized with the rotation angle of the internal combustion engine, so that an approximate difference between the number of pumps of the fuel supply pump and the number of injections of the fuel injection valve performed during one combustion stroke of the internal combustion engine. A section (that is, a determination period and a pump control period) in which the number of times of pumping and the number of times of injection determined by a value or a value obtained by multiplying the fractional value by an integer is obtained in synchronization with the rotational speed of the internal combustion engine.
[0011]
(Means of claim 6)
Claim 2 In the accumulator fuel injection device described in
The pump control means is characterized by stopping the discharge of the fuel supply pump within the pump control period.
In this case, since the fuel supply pump can be excluded from the cause of fuel leakage, the fuel leakage can be determined more accurately.
[0012]
(Means of claim 7)
Claim 2 In the accumulator fuel injection device described in
The pump control means fixes the discharge amount of the fuel supply pump to an arbitrary amount within the pump control period.
In this case, by fixing the pump discharge amount to an arbitrary amount without stopping the operation of the fuel supply pump, the fuel pressure in the pressure accumulating chamber can be maintained at the target value even when fuel leakage is determined.
[0013]
(Means of Claim 8)
Claim 2 In the accumulator fuel injection device described in
The pump control means repeatedly performs the pump discharge amount limiting operation and the normal operation for a predetermined period, and the timing for switching between the pump discharge amount limiting operation and the normal operation is the speed of the internal combustion engine, the target fuel pressure in the pressure accumulating chamber, the fuel injection It is characterized in that at least one of the target injection amounts of the valve is variably controlled for each operation region.
For example, the higher the rotational speed of the internal combustion engine, that is, the higher the speed of operation, the higher the required pressure value (target value) of the pressure accumulating chamber and the greater the injection amount. In this case, if the cycle for repeating the pump discharge amount limiting operation and the normal operation is short, there is a possibility that the fuel pressure in the pressure accumulating chamber cannot be increased to the target value. Therefore, by variably controlling the timing for switching between the pump discharge amount limiting operation and the normal operation for each operating region, for example, by setting the cycle for performing the pump discharge amount limiting operation longer as the operation speed becomes higher, the fuel pressure in the pressure accumulator chamber is set. The target value can be maintained.
[0014]
(Means of claim 9)
Claim 2 In the accumulator fuel injection device described in
The fuel leakage determining means has a discharged fuel amount calculating means for calculating the amount of fuel released from the pressure accumulating chamber during the pump discharge amount limiting operation, and the discharged fuel amount calculating means is discharged from the pressure accumulating chamber. The amount of fuel to be used is calculated by converting the amount of fuel pressure change in the pressure accumulating chamber before and after the pump control period into a fuel amount.
[0015]
(Means of claim 10)
Claim 2 In the accumulator fuel injection device described in
The pump control means is characterized in that when the acceleration request of the internal combustion engine is detected during the pump control period, the pump discharge amount limiting operation is immediately stopped. Thereby, the pressure supply from the fuel supply pump can be performed in response to the acceleration request.
[0016]
(Means of Claim 11)
Claim 2 In the accumulator fuel injection device described in
The pump control means delays the acceleration request until the determination process of the fuel leak determination means is completed when the acceleration request of the internal combustion engine is detected during the pump control period. Thereby, it is possible to avoid the determination process of the fuel leakage determination means and the acceleration operation of the internal combustion engine in response to the acceleration request from being performed simultaneously.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a system configuration diagram of a pressure accumulation type fuel injection device of the present invention.
The accumulator fuel injection device 1 of this embodiment is applied to a 6-cylinder diesel engine 2 (hereinafter referred to as the engine 2). As shown in FIG. 1, a feed pump 4 for pumping fuel from a fuel tank 3; A fuel supply pump 5 that pressurizes and discharges the fuel pumped up by the feed pump 4, a common rail 6 (accumulation chamber of the present invention) that accumulates high-pressure fuel discharged from the fuel supply pump 5, and the common rail 6 A fuel injection valve 8 that injects high-pressure fuel supplied through a higher-pressure pipe 7 into the cylinder of the engine 2 and electronic control that controls the operation of the system based on information detected by various sensors (described later). Device (hereinafter referred to as ECU 9).
[0018]
The fuel supply pump 5 has a built-in electromagnetic valve 5a that opens and closes a suction passage (not shown), and determines the fuel discharge amount based on the valve closing start timing of the electromagnetic valve 5a. This fuel supply pump 5 is a tandem type having two discharge paths, and the discharge amount to the common rail 6 is controlled by two systems by two electromagnetic valves 5a corresponding to the respective discharge paths (see FIG. 2). .
The fuel injection valve 8 incorporates an electromagnetic valve 8a that opens and closes a low-pressure passage leading to a pressure control chamber (not shown), and determines the injection amount and the injection timing by the opening / closing operation of the electromagnetic valve 8a. The fuel injection valve 8 is attached to each cylinder of the engine 2 and performs fuel injection in the order of # 1- # 2- # 3- # 4- # 5- # 6 cylinders.
[0019]
Various sensors that provide information to the ECU 9 include an engine rotation speed sensor 10 that detects the rotation speed of the engine 2 (which may be built in the fuel supply pump 5), and a depression amount (accelerator opening) of the accelerator pedal 11. An accelerator opening sensor 12 for detecting, a coolant temperature sensor 13 for detecting the temperature of engine coolant, a pressure sensor 14 for detecting pressure in the common rail 6, and a temperature of return fuel returning from the fuel injection valve 8 to the low pressure path are detected. There is a fuel temperature sensor 15. In addition, an engine load sensor, an injection timing sensor, an intake pressure sensor, an intake air temperature sensor, or the like may be used.
[0020]
The ECU 9 calculates the pump discharge amount pumped from the fuel supply pump 5 to the common rail 6, the injection amount injected from the fuel injection valve 8 into the cylinder of the engine 2, and the injection timing, and is incorporated in the fuel supply pump 5 according to the calculation result. The operation of the solenoid valve 5a and the operation of the solenoid valve 8a built in the fuel injection valve 8 are electronically controlled. Note that control methods related to the discharge amount of the fuel supply pump 5, the injection amount of the fuel injection valve 8, and the injection timing are well known in the art and will not be described here.
The ECU 9 has a function as an abnormality detecting means for detecting an abnormality of the fuel system (for example, fuel leakage, pump failure, etc.). However, the fuel system means the entire fuel flow path (that is, the feed pump 4, the fuel supply pump 5, the common rail 6, the fuel until the fuel pumped up from the fuel tank 3 by the feed pump 4 is injected from the fuel injection valve 8. Fuel pipe including the injection valve 8 and the high-pressure pipe 7).
[0021]
Next, the abnormality detection means of the ECU 9 will be described.
First, the overall configuration of the abnormality detection means will be described with reference to FIG.
The abnormality detection means of the ECU 9 is an approximately difference between the number of injections of the fuel injection valve 8 (six times) and the number of pumping times of the fuel supply pump 5 (four times) performed during one combustion stroke (720 ° CA) of the engine 2. A section (360 ° CA) with the value (3 injections / 2 pumping) as one group is executed as an abnormality detection determination section.
The abnormality detecting means includes a fuel leakage amount calculating means 16 for managing fuel leakage periodically (every 360 ° CA), and comparing the fuel leakage amount calculated by the fuel leakage amount calculating means 16 with a judgment value. Abnormality temporary determination means 17 for determining the presence or absence of fuel, and abnormality main determination means for determining whether or not fuel leakage has truly occurred when the determination means determines that there is an abnormality (provisional abnormality determination). 18, an abnormal main determination time calculation unit 19 that measures the processing time of the abnormal main determination unit 18, and a pump pressure limit control unit 20 that limits the pump discharge amount of the fuel supply pump 5.
[0022]
Subsequently, each configuration (means) of the above-described abnormality detection means will be described in detail with reference to a control block diagram shown in FIG.
(1) Fuel leakage amount calculation means 16
From the various information of the engine 2 given by various sensors, the pump discharge amount at the time of operation: Qpump, the fuel injection amount: Qtotal, the planned leak amount: Qinj, the internal pressure change equivalent amount of the common rail 6: Qpc is calculated, and the following formula Calculate the fuel leakage amount: Qleak.
Qleak = Qpump-(Qtotal + Qinj + Qpc)
However, in this embodiment, one cycle (360 ° CA) of the four-cycle, six-cylinder engine 2 is used as the determination section for the abnormality detection process, so the details of each calculation are as follows.
[0023]
a) Pump discharge rate: Qpump
Since the engine is rotated twice by one rotation, Qpump is the total pump discharge for two pumps. The calculation of the pump discharge amount is a value obtained by subtracting the pump discharge loss amount from the product of the plunger sectional area in the fuel supply pump 5 and the plunger stroke (suction stroke width) at that time.
b) Fuel injection amount: Qtotal
Since three injections are performed in one rotation of the engine, the injection command value (target injection amount) for the three injections is the sum.
[0024]
c) Planned leak amount: Qinj
This planned leak amount is the sum of the leak amounts generated from the six fuel injection valves 8 in the time corresponding to one engine revolution, and the static leak amount that regularly generates the leak and the movement that occurs when the fuel injection valve 8 is driven. This is the sum of the leak amount (switching leak).
The static leak amount is the sum of the leak amounts from the six fuel injection valves 8 between 360 ° CA, and is obtained from an empirical formula of injector static leak characteristics determined from at least one of common rail pressure, fuel temperature, and engine speed. Can do.
The dynamic leak amount can be obtained from an empirical formula of injector dynamic leak characteristics determined from at least one of the switching time of the fuel injection valve 8, the common rail pressure, and the fuel temperature.
d) Amount equivalent to internal pressure change of common rail 6: Qpc
The amount corresponding to the internal pressure change of the common rail 6 is a value obtained by converting the change in the internal pressure of the common rail 6 in one rotation of the engine into the change in the fuel amount from the internal volume of the common rail 6 and the bulk elastic modulus.
[0025]
Here, the principle of fuel leakage amount calculation will be described with reference to FIG.
When there is no fuel leakage, the calculated pump discharge amount is equivalent to the (fuel injection amount + scheduled leak amount + equivalent amount of change in internal pressure of the common rail 6), and as shown in FIG. The fuel balance is balanced.
However, when fuel leakage occurs, the fuel supply pump 5 feeds back and increases the amount of leakage in order to maintain the target common rail pressure, and as shown in FIG. Will increase. On the other hand, since (fuel injection amount + scheduled leak amount + equivalent amount of change in internal pressure of common rail 6) has not changed, the deviation {pump discharge amount− (fuel injection amount + scheduled leak amount + change in internal pressure of common rail 6). Equivalent amount)} is calculated as the fuel leakage amount Qleak.
[0026]
A processing procedure for calculating the fuel leakage amount will be described with reference to a control flowchart shown in FIG. This routine is executed every 360 ° CA.
First, at step 101, the state of the fuel leak determination flag fleak is determined. Here, if fleak is set (fleak = 1), it is determined that it has already been determined, and this routine is terminated.
Similarly, when the pump failure determination flag fpump is set (fpump = 1) in step 102 and when the abnormal temporary determination flag flakb is set (fleakb = 1) in step 103, it is determined that the determination has already been made. End the routine.
If it is not judged, that is, if neither fpump nor fleakb is set, the pump discharge amount Qpump, the fuel injection amount Qtotal, the planned leak amount Qinj, and the fuel amount Qpc corresponding to the internal pressure change of the common rail 6 are calculated in steps 104 to 107. In step 108, the fuel leakage amount Qleak is calculated.
[0027]
(2) Temporary abnormality determination means 17 (abnormality presence / absence determination means of the present invention)
As shown in FIG. 4, the abnormal temporary determination means 17 compares the fuel leakage amount Qleak obtained by the fuel leakage amount calculation means 16 with a temporary determination value, and the relationship of Qleak> provisional determination value, that is, temporary determination. When the fuel leakage amount Qleak is larger than the value, the abnormal temporary determination flag fleakb is set (fleakb = 1).
The provisional determination value is set to a value that is not erroneously determined in consideration of tolerances of system components, assembly tolerances, and the like (see FIG. 7).
[0028]
Here, the processing procedure of the temporary abnormality determination means 17 will be described based on the control flowchart shown in FIG. This routine is executed every 360 ° CA.
First, in steps 201 and 202, the state of the fuel leakage determination flag fleak and the pump failure determination flag fpump is determined. If any of the flags is set and determined, this routine is terminated.
If not judged, that is, if neither fleak nor fpump is set, the state of the abnormal provisional judgment flag fleakb is judged in step 203.
When fleakb is not set (fleakb = 1), the routine proceeds to step 204, where the fuel leakage amount Qleak is calculated as an average value with the past four data to suppress variations in Qleak.
[0029]
When fleakb is set in step 203, the process proceeds to step 205, and a new average value of Qleak is not calculated.
In step 205, the fuel leakage amount Qleak is determined as a temporary judgment value (100 mm in this embodiment). ^Three / 360 ° CA).
If the provisional judgment value is larger than the fuel leakage amount Qleak in step 205, the state of the abnormal provisional judgment flag fleakb is judged in step 206. If fleakb is set, fleakb is reset in step 207 ( fleakb = 0).
When the fuel leakage amount Qleak is larger than the temporary determination value at step 205, the state of the abnormal temporary determination flag fleakb is determined at step 208. When fleakb is not set, fleakb is set at step 209 (fleakb = 1) Do it.
[0030]
(3) Pump pressure feed restriction control means 20 (pump control means of the present invention)
As shown in FIG. 4, the pump pressure limit control unit 20 switches the drive control of the fuel supply pump 5 based on the result of the abnormal temporary determination flag fleakb determined by the abnormal temporary determination unit 17.
When flakeb is set by the temporary abnormality determination means 17, that is, when it is determined that "there is an abnormality such as fuel leakage", pump pressure limit control is started.
When flakeb is not set by the temporary abnormality determination means 17, that is, when it is determined that “no abnormality such as fuel leakage”, normal feedback for maintaining the common rail pressure at the target value for the fuel supply pump 5. Continue control. This control is shown in a sequential time chart as shown in FIG.
The discharge amount of the fuel supply pump 5 is proportional to the amount of fuel to be sucked, and the amount of sucked fuel, as shown in FIG. 10, is determined at any timing (shaft angle) of the pump cam shaft that moves the plunger 5b up and down. (Valve opening timing is fixed). The discharge amount is controlled by controlling the camshaft angle (pump suction angle) TFE where the electromagnetic valve 5a is open.
[0031]
Here, the processing procedure of the pump pressure limit control means 20 will be described based on the control flowchart shown in FIG. This routine is executed every 180 ° CA.
First, in step 301, the state of the abnormal temporary determination flag fleakb is determined. If fleakb is not set, it is determined that there is “temporary determination”, a normal pump suction angle TFE is calculated in step 302, and this routine is terminated.
If fleakb is set, it is determined that “abnormal provisional determination has been completed” and the process proceeds to step 303.
[0032]
In step 303, the state of the pump pressure limit section discrimination counter CPUMP is judged. When CPUMP is not zero (CPUMP.noteq.0), normal processing is performed in step 302 as described above, and this routine is terminated.
The pump pressure limit section discrimination counter CPUMP is a counter incremented every 720 ° CA (see steps 405 to 414 in FIG. 12 / details will be described later).
When CPUMP = 0 in step 303, the state of the cylinder discrimination counter CCYLN is determined in steps 304 and 305. Since the cylinder discrimination counter CCYLN is a 6-cylinder engine, it is a counter that is incremented every 120 ° CA (see steps 401 to 404 in FIG. 12).
[0033]
When CCYLN = 1 and CCYLN = 3 in steps 304 and 305 (pump control timing points A and B in FIG. 2), the pump suction angle TFE is set to TFE = 0 deg in step 306 and the fuel supply pump 5 is set. Instruct to stop inhalation.
If it is not the above timing in steps 304 and 305, the normal processing is performed in step 302, and the routine is terminated.
By the above pump control, as shown in FIG. 2, the suction control is performed between 360 ° CA in the A to C sections, and the fuel pumping is stopped between 360 ° CA in the BD sections.
When this is repeated, the operation of the fuel supply pump 5 is limited and controlled in a manner similar to the pump suction angle TFE shown in FIG. Note that the common rail pressure can be maintained by regularly performing normal control.
[0034]
Next, details of the cylinder discrimination counter CCYLN and the pump pressure limit section discrimination counter CPUMP will be described with reference to a control flowchart shown in FIG. This routine is executed every 120 ° CA.
The determination of 120 ° CA is made in step 401 based on whether or not each cylinder compression TDC is ATDC 30 ° CA. When the timing is ATDC 30 ° CA in step 401, the routine proceeds to step 402, where # 6 cylinder is determined. If it is # 6 cylinder, CCYLN is cleared (CCYLN = 0) in step 403, and if it is not # 6 cylinder, CCYLN is incremented in step 404.
By this operation, after CCYLN is cleared in the # 6 cylinder, the count is incremented every 120 ° CA from 0 to 5 between 720 ° CA.
[0035]
Subsequently, at step 405, CCYLN = 0 is determined, and when CCYLN ≠ 0, this routine is terminated.
Next, in steps 406 to 411, the pump pressure control mode PUMPMOD is set. Step 406 and subsequent steps are executed every 720 ° CA.
In this embodiment, the pump pressure limit cycle is lengthened as the engine speed increases. This is because the higher the high-speed operation, the higher the required value of the common rail pressure and the greater the injection amount, and therefore the common rail pressure cannot be increased to the target value if the pump pressure limit cycle is short.
[0036]
In steps 406 to 411, the engine speed NE is set to the following mode.
NE <1000rpm → PUMPMOD = 0
1000 ≦ NE <3000rpm → PUMPMOD = 1
NE ≧ 3000rpm → PUMPMOD = 2
Next, in step 412, the pump pressure limit section discrimination counter CPUMP is compared with the PUMPMOD. If CPUMP <PUMPMOD, CPUMP is incremented in step 413, and if CPUMP ≧ PUMPMOD, CPUMP in step 414. Is cleared (CPUMP = 0).
[0037]
By the operations in steps 412 to 414, the pump pressure limit cycle is set as follows.
When PUMPMOD = 0 → 720 ° CA (2 engine rotations)
When PUMPMOD = 1 → 1440 ° CA (4 engine rotations)
When PUMPMOD = 2 → 2160 ° CA (6 engine rotations)
The pumping stop period of the fuel supply pump 5 is a 360 ° CA interval between pump pumping restriction cycles.
The behavior of the above pump pressure limit control is shown in the time chart of FIG.
[0038]
(4) Abnormal main determination means 18 (fuel leakage determination means of the present invention)
As shown in FIG. 4, the abnormality main determination means 18 is the pump pressure limit control means described in (3) above when the abnormality temporary determination flag 17 is set (fleakb = 1) by the abnormality temporary determination means 17. 20 in conjunction with. Specifically, the amount of common rail pressure drop due to the injection at the time of pump pressure restriction and the leak from the fuel injection valve 8 is converted into the fuel amount Qdown, and the fuel amount Qdown is compared with a predetermined main determination value. Here, when Qdown> this judgment value, it is judged as “fuel leakage”, and when Qdown <this judgment value continues for a predetermined time, it is judged as “pump failure” due to pump suction failure or the like.
[0039]
Here, a phenomenon when a pump suction failure occurs will be described.
When a pump suction failure occurs, even if no fuel leakage occurs, the fuel supply pump 5 performs feedback control to the discharge amount increasing side, so that the pump suction angle TFE increases and the pump discharge amount calculation value Qpump becomes To increase. As a result, the same condition as the fuel leakage condition shown in FIG. 5B occurs, and an abnormal provisional determination (fleakb = 1) is made.
Therefore, in order to distinguish between “fuel leakage” and “pump failure”, it is necessary to eliminate the factor of pump control (pump pumping restriction control) and make this determination.
[0040]
Next, the method up to the acquisition of the common rail pressure drop amount in the abnormality main determination means 18 will be described with reference to the time chart of FIG.
The pump pressure limit control means 20 stops the pump pressure feed between 360 ° CA of B to D in FIG. 2, and the common rail by three injections in the meantime (# 4, # 5, # 6 cylinders in this embodiment). The common rail pressure drop amount (ΔNPC in FIG. 2) due to the pressure drop, the static leak amount of the fuel injection valve 8 for the six cylinders, and the dynamic leak amount for the three cylinders accompanying the injection is set to ATDC 30 ° CA of each cylinder. Measured from the set common rail pressure NPC (B point NPC-D point NPC in Fig. 2).
[0041]
Next, the processing procedure of the abnormality main determination means 18 will be described based on the control flowchart shown in FIG. This routine is executed every 360 ° CA.
First, in steps 501 and 502, the state of the fuel leakage determination flag fleak and the pump failure determination flag fpump is determined. If any of the flags is set and determined, this routine ends.
When fleak and fpump are not set, the state of the abnormal temporary determination flag fleakb is determined at step 503. When fleakb is set, the values of the pump pressure limit section discrimination counter CPUMP and cylinder discrimination counter CCYLN are judged in steps 504 and 505, and when CPUMP and CCYLN are zero, that is, the pump pressure limit section. After determining the end point (point D in FIG. 2), the process proceeds to step 506. Here, when CPUMP ≠ 0 and CCYLN ≠ 0, it is determined that it is not an abnormal main determination timing, and this routine is terminated.
[0042]
In step 506, it is determined whether the abnormal main determination elapsed time counter CLEAK (details will be described later) is equal to or greater than a predetermined value (5 sec in this embodiment). If it is within the predetermined value, in step 507, the common rail in the pump pressure limit section is determined. Calculate the pressure drop DLNPC. This DLNPC is the pressure drop amount ΔNPC between points B and D in FIG.
In step 508, DLNPC is converted into a fuel amount change equivalent amount Qdown by the following equation, and in step 509, it is averaged with the past four DLNPCs.
Qdown = DLNPC × (High-pressure part volume / bulk elastic modulus)
High-pressure part volume = COMO rail volume + high-pressure pipe volume
[0043]
Subsequently, at step 510, an injection command value (3 injections) Qfin 360 to the fuel injection valve 8 within the pump pressure limit section 360 ° CA is calculated (# 4, # 5, # 6 cylinder injection commands in FIG. 2). Sum of values).
Subsequently, in step 511, the sum of the static leak amount Qils and the dynamic leak amount Qild in the same section (360 ° CA) as described above is calculated as the total leak Qinj 360.
Subsequently, in step 512, Qinj 360 is added to Qfin 360 to calculate an abnormal main determination reference value QLEAKJD (QLEAKJD = Qfin 360 + Qinj 360), and further, in step 513, averaged four times and stabilized.
Here, QLEAKJD is the amount of fuel released between 360 ° CA from the common rail 6 when there is no fuel leakage, that is, when it is normal, and this is the abnormal main determination reference value.
[0044]
Subsequently, at step 514, the determination value (in this embodiment, 100 mm is set in QLEAKJD). ^Three / 360 ° CA) is added and compared with the value Qdown converted from the common rail pressure drop amount to the fuel amount in the pump pressure limit section (360 ° CA). Here, when it is determined that the relationship of Qdown> QLEAKJD + 100, that is, the common rail pressure drop amount is larger than the reference value (normal state), the fuel leakage determination flag fleak is set in step 515, and in step 517. The abnormal provisional determination flag fleakb that has already been determined is reset, and this routine ends.
[0045]
If it is determined in step 506 that the predetermined time (5 seconds) has not elapsed since the abnormality has not yet been determined, the abnormality temporary determination by the abnormality temporary determination means 17 is not caused by fuel leakage but by an abnormality on the pump side. If it is determined that there is, a pump failure determination flag fpump is set at step 516, and this routine is terminated via step 517.
The time chart of FIG. 15 shows an outline from taking in the amount of common rail pressure drop to determining the actual abnormality.
[0046]
(5) Abnormal book determination time calculation means 19
As shown in FIG. 4, this means starts the elapsed time measurement by using the result of the abnormal temporary determination flag fleakb determined by the abnormal temporary determination means 17 as a trigger.
A processing procedure of the abnormality main determination time calculation means 19 will be described based on a control flowchart shown in FIG. Since this routine is set during the 1 second routine, this routine is executed every 1 second.
First, in step 601, the state of the abnormal temporary determination flag fleakb is determined. If fleakb is set here, an abnormal main determination elapsed time counter CLEAK is incremented in step 602.
[0047]
Subsequently, in steps 603 and 604, the CLEAK upper limit guard (6 in this embodiment) is set, and this routine ends. This guard value is a value obtained by adding “1” to the predetermined value (5) set in step 506 in the control flowchart shown in FIG.
If the abnormal temporary determination flag fleakb is not set at step 601 (abnormal temporary determination is not performed), the abnormal main determination elapsed time counter CLEAK is cleared at step 605 and the routine is terminated.
[0048]
(Effect of this embodiment)
In the pressure accumulation type fuel injection device 1 of the present embodiment, the number of injections of the fuel injection valve 8 (six times) and the number of pumping times of the fuel supply pump 5 (four times) performed during one combustion stroke (720 ° CA) of the engine 2 are performed. ) Is set as a determination section, and the fuel system abnormality is more accurately detected even if the fuel injection timing and the fuel pumping timing overlap. (Such as fuel leakage or pump failure) can be determined. Therefore, the present invention is not limited to a system in which the number of injections (the number of cylinders) matches the number of pumping times (for example, four injections / four pressures), but is also applied to a system in which the number of injections (number of cylinders) and the number of pumping times described in this embodiment are different The fuel system abnormality determination process can be executed for various engines without being influenced by the number of engine cylinders (number of injections) and the number of pumping pumps.
[0049]
(Modification)
In the above-described embodiment, in the six-cylinder internal combustion engine (6 injection / 4 pressure feeding), the abnormality temporary determination section in the abnormality temporary determination means 17 and the abnormality main determination section (pump pumping restriction section) in the abnormality main determination means 18 are three injections. / 2 is set in a section in which one pumping is set as one group. The relationship between the number of pumping of the fuel supply pump 5 and the number of injection of the fuel injection valve 8 is the number of pumping performed during one combustion stroke of the internal combustion engine. The same effect can be obtained by controlling the interval between the number of injections and the number of times of pumping determined by an integral multiple of the number of injections and the number of injections as an abnormal temporary determination interval and abnormal main determination interval. Can be obtained. For example, in a 4-injection / 2-pumping system, the 2-injection / 1-pumping group is a group. Between An abnormal temporary determination section and an abnormal main determination section can be used.
[0050]
In the above embodiment, in step 306 in FIG. 11, the pump supply angle of the fuel supply pump 5 is stopped by setting the pump suction angle TFE = 0 deg to limit pump pumping, but any fixed value (for example, TFE = 10 deg) As described above, the same effect can be obtained by correcting the amount fed by the fixed value by the calculation formula in step 508 in FIG.
In this case, step 508 is replaced with the following equation.
Qdown ← DLNPC * (Volume of high pressure / bulk elastic modulus) -FD
(FD: Calculated amount of fuel pumped by pump suction angle TFE = 10deg)
[0051]
In the above embodiment, in steps 406 to 411 in FIG. 12, the execution cycle of the pump pressure restriction is switched by the engine speed NE, but the same effect can be obtained even by switching by the common rail target pressure or the target injection amount. If the conditions are combined (for example, the operating range determined by NE and common rail pressure), the performance of the fuel supply pump 5 in the present invention can be further improved.
In the above embodiment, the predetermined determination time (5 sec) for determining whether “fuel leakage” or “pump failure” is set to a fixed value in step 506 in FIG. 14. The accuracy of the present invention can be improved by varying the determination time according to at least one parameter of the target pressure and the target injection amount.
[Brief description of the drawings]
FIG. 1 is a system configuration diagram of an accumulator fuel injection device.
FIG. 2 is a control time chart relating to abnormality detection processing;
FIG. 3 is a control block diagram related to abnormality detection processing;
FIG. 4 is a detailed control block diagram related to abnormality detection processing;
FIG. 5 is a diagram illustrating the principle of fuel leakage amount calculation.
FIG. 6 is a flowchart showing a processing procedure for calculating a fuel leakage amount.
FIG. 7 is a time chart relating to temporary abnormality determination.
FIG. 8 is a flowchart showing a processing procedure of a temporary abnormality determination unit.
FIG. 9 is a time chart relating to temporary abnormality determination and pump pressure limit control.
FIG. 10 is an explanatory diagram relating to pump suction amount (discharge amount) control.
FIG. 11 is a flowchart showing a processing procedure of a pump pressure limit control unit.
FIG. 12 is a flowchart showing a processing procedure for CCYLN and CPUMP count up.
FIG. 13 is a control time chart based on each pumping pressure restriction mode.
FIG. 14 is a flowchart showing a processing procedure of an abnormality main determination unit.
FIG. 15 is a time chart relating to the abnormality main determination.
FIG. 16 is a flowchart illustrating a processing procedure of an abnormality main determination time calculation unit.
[Explanation of symbols]
1 Accumulated fuel injection system
2 Engine (Internal combustion engine)
5 Fuel supply pump
6 Common rail (accumulation chamber)
8 Fuel injection valve
9 ECU
16 Fuel leak amount calculation means
17 Temporary abnormality determination means (abnormality presence / absence determination means)
18 Abnormal main judging means (fuel leakage judging means)
19 Abnormal book determination time calculation means
20 Pump pressure limit control means

Claims (11)

A fuel supply pump that pressurizes and discharges fuel; and
A pressure accumulating chamber for storing fuel pumped from the fuel supply pump in a high pressure state;
A fuel injection valve for injecting high-pressure fuel supplied from the pressure accumulating chamber into the cylinder of the internal combustion engine;
An abnormality presence / absence judging means for judging whether or not there is an abnormality such as fuel leakage in the fuel system ,
A pressure accumulation type fuel injection device in which the number of pumping of the fuel supply pump performed during one combustion stroke of the internal combustion engine and the number of injections of the fuel injection valve do not match ,
A discharge amount calculating means for calculating a discharge amount of fuel discharged from the fuel supply pump to the pressure accumulation chamber;
Target injection amount calculating means for calculating a target injection amount necessary for combustion of the internal combustion engine;
A planned leak amount calculating means for calculating the amount of fuel that mechanically leaks from the fuel injection valve; and a pressure change equivalent fuel amount calculating means for calculating an amount of fuel corresponding to a change in fuel pressure in the accumulator. Prepared,
Set before Ki圧 feed times before Ki噴 reduced fraction value of the morphism number or to one group of the pumping times and injection times determined the reduced fraction value at an integral multiple value interval as the determination period,
When the total of the target injection amount, the leak amount, and the pressure change equivalent amount included in the determination period is defined as the released fuel amount,
The abnormality presence / absence determining means determines whether there is an abnormality in the fuel system in the determination period based on a balance between the total discharge amount included in the determination period and the released fuel amount. Accumulated fuel injection system. In the pressure accumulation type fuel injection device according to claim 1,
A pump control means for performing a pump discharge amount limiting operation for limiting a discharge amount of the fuel supply pump when the abnormality presence / absence determination means determines that there is an abnormality;
Fuel for calculating the amount of fuel released from the pressure accumulating chamber during the pump discharge amount limiting operation and determining whether or not fuel leakage has occurred in the fuel system based on the calculated fuel amount Leakage determining means,
The number of times of pumping and the number of times of injection determined by an approximate value of the number of times of pumping of the fuel supply pump and the number of times of injection of the fuel injection valve performed during one combustion stroke of the internal combustion engine, or a value obtained by multiplying the divisor value by an integral multiple And set as a group of pump control period
The pressure-accumulating fuel injection device , wherein the pump control means limits a discharge amount of the fuel supply pump within the pump control period . The pressure accumulation type fuel injection device according to claim 2 ,
The fuel leakage determination means compares the calculated fuel amount with a determination value, and determines that fuel leakage has occurred in the fuel system when the calculated fuel amount is larger than the determination value. Fuel injector. In the pressure accumulation type fuel injection device according to claim 1 ,
The accumulator fuel injection apparatus according to claim 1, wherein the determination period is a period obtained in synchronization with the rotational speed of the internal combustion engine . The pressure accumulation type fuel injection device according to claim 2 ,
Before SL pump control period, an accumulator fuel injection system, wherein the a period obtained in synchronization with the rotation speed of the internal combustion engine. The pressure accumulation type fuel injection device according to claim 2 ,
The pressure-accumulating fuel injection device, wherein the pump control means stops discharge of the fuel supply pump within the pump control period. The pressure accumulation type fuel injection device according to claim 2 ,
The pressure-accumulating fuel injection device, wherein the pump control means fixes the discharge amount of the fuel supply pump to an arbitrary amount within the pump control period. The pressure accumulation type fuel injection device according to claim 2 ,
The pump control means repeatedly performs the pump discharge amount limiting operation and the normal operation for a predetermined period. An accumulator fuel injection device, wherein at least one of pressure and a target injection amount of the fuel injection valve is used as a parameter, and is variably controlled for each operation region. The pressure accumulation type fuel injection device according to claim 2 ,
The fuel leakage determining means has a released fuel amount calculating means for calculating the amount of fuel released from the pressure accumulating chamber while the pump discharge amount limiting operation is being performed,
The discharged fuel amount calculating means calculates the amount of fuel released from the pressure accumulating chamber by converting the amount of fuel pressure change in the pressure accumulating chamber before and after the pump control period into a fuel amount. Injection device. The pressure accumulation type fuel injection device according to claim 2 ,
The pressure accumulation type fuel injection device characterized in that the pump control means immediately stops the pump discharge amount limiting operation when an acceleration request of the internal combustion engine is detected during the pump control period. The pressure accumulation type fuel injection device according to claim 2 ,
The pressure accumulating fuel is characterized in that the pump control means delays the acceleration request until the determination process of the fuel leakage determination means is completed when the acceleration request of the internal combustion engine is detected during the pump control period. Injection device.

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