JP4312938B2 - Time-varying determination device for fuel injection device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a time-dependent change determination device for a fuel injection device.
[0002]
[Prior art]
As a conventional method for diagnosing a change with time (deterioration with time) of the fuel injection device, idle speed control (ISC control) during idle operation is performed, and the time is determined based on the ISC control amount and the load due to the alternator drive. Techniques for performing change diagnosis have been proposed (JP-A-6-272598, JP-A-6-272600, JP-A-6-294347, etc.). According to such a conventional apparatus, since the diagnosis of change with time is always performed under the same conditions, variations in evaluation of change with time have been eliminated.
[0003]
[Problems to be solved by the invention]
In the above-described prior art, there is no particular problem in stabilizing the rotation speed of each cylinder. However, in a multi-cylinder engine, there is a variation between cylinders inherent to the engine. Therefore, the fuel injection device must be considered without considering the variation between the cylinders. It is not a correct diagnosis of changes over time. Further, when the same time change occurs in all the cylinders of the engine, it is considered that the degree of time change cannot be grasped for each cylinder.
[0004]
In the future, it is considered to promote multi-stage injection (multi-injection) in order to clear regulations such as exhaust regulations and noise regulations that will be further strengthened. In addition, it is necessary to accurately correct the injection timing. In such a case, there arises a problem that the above-described prior art cannot perform sufficient correction suitable for each injection.
[0005]
The present invention has been made paying attention to the above-mentioned problems, and the object of the present invention is to provide a fuel injection device that can realize highly accurate temporal change determination in consideration of engine-specific cylinder-to-cylinder variations. It is to provide a device for determining change over time.
[0006]
[Means for Solving the Problems]
  A fuel injection device such as a pump device or a fuel injection valve changes over time with use. When comparing before and after the change over time, the injection characteristics of each cylinder by the fuel injection device change after the change over time. In such a situation, in the invention according to claim 1,As the rotation information for each cylinder, the rotation increase amount during the expansion stroke and the instantaneous minimum rotation speed immediately before the expansion stroke are acquired (rotation information acquisition means), and based on the acquired rotation increase amount and the instantaneous minimum rotation speedThe actual injection amount actually injected from the fuel injection valve is estimated for each cylinder (actual injection amount estimating means),thisEstimatedIsActual injection amountWhenA time-dependent change amount of the fuel injection device is calculated by comparison with an actual injection amount before a time-change stored in advance for each cylinder (time-dependent change amount calculating means).
[0007]
  According to the above invention,Based on the amount of increase in rotation during the expansion stroke and the instantaneous minimum rotation speed immediately before the expansion strokeSince the amount of change over time of the fuel injection device is calculated based on the difference between the actual injection amount that is estimated for each cylinder as needed and the actual injection amount that has been stored in advance before the change over time, there is a variation between cylinders inherent to the engine. Even if this is the case, it is possible to determine the change with time in consideration of the variation. Further, even if the same change with time occurs in all the cylinders, it can be individually determined without canceling the change with time. As a result, it is possible to realize highly accurate temporal change determination.In addition, since the amount of increase in rotation during the expansion stroke differs depending on the instantaneous minimum rotational speed immediately before the expansion stroke, the actual injection amount considering the explosion force for each cylinder is used not only by the rotational increase amount but also by using the instantaneous minimum rotational speed. Since the estimation is performed, it is possible to estimate the actual injection amount with higher accuracy.
[0010]
  Further, as a condition for performing the rotation information acquisition by the rotation information acquisition means and the time change calculation by the time change calculation means, it is during idling or in a steady stable state.2) And the engine speed during idling is controlled to the target value.3). That is, in idle operation or in a steady stable state, a change in rotational behavior with time changes appears significantly. In particular, when the idling engine speed is controlled to the target value, the engine speed becomes stable, and therefore the rotational behavior associated with changes over time becomes even more pronounced. Therefore, by using the rotation information under the above execution conditions, the actual injection amount can be easily estimated, and as a result, the change with time can be determined easily and accurately.
[0011]
  When the fuel injection control of the vehicle engine is performed, generally, various corrections are performed on the basic injection amount set from the engine speed and the load to determine the final injection amount command value. Then, fuel injection is performed by this final injection amount command value, and the engine is operated. In other words, when considering the individual combustion cycles in each cylinder, the actual injection amount includes the basic injection amount equivalent and the correction equivalent, and the correction equivalent greatly depends on the engine operating state at that time. The Therefore, the claim4In the invention described in, the actual injection amount corresponding to the basic injection amount is calculated for each cylinder based on the result obtained by subtracting the correction amount corresponding to the engine operating state at that time from the estimated actual injection amount. Then, the temporal change amount of the fuel injection device is calculated by comparing the calculated actual injection amount corresponding to the basic injection amount and the actual injection amount corresponding to the basic injection amount before the temporal change stored in advance. Thereby, it is possible to determine the change with time with higher accuracy.
[0012]
  Claims5In the invention described in (1), since the change over time of the fuel injection device calculated by the time change calculation means is stored in the backup memory for each cylinder, the change over time for each cylinder can be accurately grasped. Further, by backing up the change over time and appropriately updating (learning) the backup value, it is possible to always accurately grasp the change over time of the fuel injection device.
[0013]
  Claim6In the invention described in (1), when the initial condition considered to be before the change with time is satisfied, the rotation information for each cylinder is acquired, and the actual injection amount before the change with time is calculated for each cylinder based on the acquired rotation information. The result is stored in the backup memory.
In this case, the actual injection amount before the change with time also takes into account the variation between the cylinders inherent to the engine in the same manner as the estimated actual injection amount (the actual injection amount after the change with time). Improves.
[0014]
  Furthermore, the claim7In the invention described in the above, the fuel injection amount to each cylinder is corrected based on the temporal change amount of the fuel injection device calculated by the temporal change amount calculating means (correction means). In this case, it is possible to maintain the same injection characteristics as before the change even after the fuel injection device changes with time.
[0015]
  The present invention relates to a fuel injection device comprising a distributed fuel injection pump and an injection nozzle.8And a fuel injection device comprising a high-pressure fuel pump, a common rail, and an electromagnetically driven injector (claims)9The change with time of these fuel injection devices can be accurately determined.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the present embodiment, in a fuel injection system of a four-cylinder diesel engine equipped with a distributed fuel injection pump, the fuel injection amount and the fuel injection timing are controlled by an electronic control unit (hereinafter referred to as ECU). The amount of change over time of the fuel injection device including a pump and an injection nozzle is grasped, and fuel injection correction is performed according to the amount of change over time. The distribution type fuel injection pump may be of either face cam pressure feeding or inner cam pressure feeding, but here, the face cam pressure feeding type will be described as an example.
[0017]
First, the face cam pressure-feed type distributed fuel injection pump 1 and the ECU 30 shown in FIG. 1 will be described. In the fuel injection pump 1, the drive shaft 2 is rotationally driven by an engine (not shown) in synchronization with a rotational speed that is a half of the rotational speed of the engine. A signal rotor 3 is coaxially attached to the drive shaft 2, and a plurality of convex teeth are formed on the outer periphery thereof. The rotation speed sensor 4 is mounted opposite to the outer periphery of the signal rotor 3, generates a pulse signal corresponding to the engine rotation speed by electromagnetic induction of the convex teeth of the signal rotor 3, and outputs the signal to the ECU 30. It should be noted that the outer periphery of the signal rotor 3 has tooth portions formed densely at equal intervals so as to generate a pulse signal (Ne pulse) corresponding to the engine speed, and missing portions of convex teeth. And a tooth portion. The missing teeth are formed at equal intervals by the number of cylinders (every 90 degrees for four cylinders).
[0018]
The drive shaft 2 is connected to a face cam 7 for driving a fuel pressure feeding plunger 6 and a vane pump 8 (developed 90 degrees in FIG. 1) as a fuel feed pump. The face cam 7 is urged to the left in the figure by a spring 9 and is thereby pressed against a roller 11 provided on the roller ring 10.
[0019]
In such a case, the face cam 7 and the plunger 6 can rotate together, and when the face cam 7 is rotationally driven by the drive shaft 2, the plunger 6 rotates in conjunction therewith. When the convex portion of the face cam 7 rides on the roller 11, the plunger 6 reciprocates in the axial direction together with the face cam 7. The plunger 6 is inserted into the pump cylinder 12 to form a pressure chamber 13 at the tip thereof, and the volume of the pressure chamber 13 is expanded and contracted by the reciprocating motion of the plunger 6. At the same time, the suction side port and the discharge side port opened in the pressure chamber 13 are switched by the rotational movement of the plunger 6 to communicate with each other.
[0020]
The fuel discharged from the feed pump 8 is stored in the fuel chamber 15. After the fuel is drawn into the pressure chamber 13 and pressurized to a high pressure, the delivery valve 16 and the high-pressure fuel passage 17 are passed through at a predetermined timing. It is pumped through to the injection nozzle 18. Then, fuel is injected from the injection nozzle 18 into each cylinder (combustion chamber) of the engine (not shown). Here, the injection nozzle 18 is provided for each cylinder of the engine. When the fuel pressure (injection pressure) supplied from the fuel injection pump 1 exceeds the valve opening pressure set by a spring or the like, the combustion of each cylinder is performed. Fuel is injected and supplied to the chamber.
[0021]
The fuel injection pump 1 is provided with an electromagnetic spill valve 19 configured as a normally open valve. By opening and closing the spill valve 19 by the ECU 30, the fuel injection start timing, the injection amount, or the injection rate is controlled. The That is, when the coil is not energized (off), the spill valve 19 is opened, and the fuel in the pressure chamber 13 is spilled (overflowed) into the fuel chamber 15. Further, when the coil is energized (ON), the spill valve 19 is closed, and the fuel spill from the pressure chamber 13 to the fuel chamber 15 is stopped.
[0022]
A hydraulic timer device 20 for adjusting the fuel injection timing is provided at the lower part of the pump. The timer device 20 adjusts the rotational position of the roller ring 10 about the axis of the drive shaft 2 to thereby engage the face cam 7 with the roller 11, that is, the reciprocating timing of the face cam 7 and the plunger 6. It has a known structure for controlling (fuel injection timing). In the drawing, for convenience, the timer device 20 is shown inverted by 90 degrees. The position of the timer piston 21 for adjusting the rotational position of the roller ring 10 is controlled by an electromagnetic hydraulic control valve 22, and the opening degree of the hydraulic control valve 22 is duty-controlled by the ECU 30. .
[0023]
The ECU 30 is composed mainly of a well-known microcomputer having a CPU 31, ROM 32, RAM 33 and other SRAM 34 as a backup memory. In addition to inputting a Ne pulse signal from the rotational speed sensor 4 described above, a cylinder discrimination signal (TDC signal) is provided. ), An accelerator opening signal indicating the degree of engine load, a coolant temperature signal, an intake air temperature signal, an air conditioner signal, and the like are input. The ECU 30 controls the drive of the spill valve 19 and the hydraulic control valve 22 of the timer device 20 based on these various input signals and the like, and optimally controls the fuel injection amount and the injection timing.
[0024]
Here, the basic operation for fuel injection will be described with reference to FIG. FIG. 2 shows an example in which multi-stage injection (multi-injection) is performed, and particularly shows a state in which main injection and pilot injection performed prior to the main injection are performed. In the figure, at time t1 to t2, the spill valve command is turned on and the spill valve 19 is closed in order to perform pilot injection. At times t3 to t4, the spill valve command is turned on and the spill valve 19 is closed in order to perform main injection.
[0025]
In FIG. 2, when the lift of the plunger 6 is started after the spill valve command is turned on at time t1, the injection pressure (fuel pressure in the pressure chamber 13) rises accordingly. When the injection pressure reaches the valve opening pressure of the injection nozzle 18, the injection nozzle 18 opens and pilot injection is performed (Qp in the figure). Thereafter, the spill valve command is turned off at time t2, and the injection pressure once decreases. However, when the spill valve command is turned on again at time t3, the injection pressure increases again. When the injection pressure reaches the valve opening pressure of the injection nozzle 18, the injection nozzle 18 opens again, and main injection is performed (Qm in the figure).
[0026]
In such a case, the ON / OFF timing (t1, t2, t3, t4) of the spill valve command is controlled for pilot injection and main injection, but the ON timing (t1) of the spill valve command before pilot injection is before the plunger lift. In addition, it is sufficient that the pressure chamber 13 is sufficiently filled with fuel, and the other timings (t2, t3, t4) are substantially strictly controlled. Actually, θ1, θ2, and θ3 for controlling the pilot injection end timing and the main injection start and end timing are based on a predetermined crank angle position (for example, the missing tooth position of the signal rotor 3). Is set. And ON / OFF of spill valve instruction | command is controlled by the pulse number and remainder angle of Ne pulse signal so that control operation by these (theta) 1-theta (3) may be obtained. Although θ1 to θ3 are control values for the spill valve command and are different from the actual injection start or end timing, in this embodiment, for convenience, θ1 is the pilot injection end timing and θ2 is the main injection timing. The start time, θ3, will be referred to as the main injection end time.
[0027]
By the way, as described above, the injection nozzle 18 performs injection when the injection pressure reaches a predetermined valve opening pressure. Since the spring is used for setting the valve opening pressure, the change in the spring over time causes the injection nozzle 18 to change. When the valve opening pressure changes, the injection characteristics for each cylinder change. In addition to the change over time of the spring, the injection characteristics change due to wear of the cam mechanism (such as the face cam 7 in FIG. 1) of the fuel injection pump 1, or the nozzle hole area is reduced by deposits formed in the nozzle nozzle holes. It is conceivable that the injection characteristic of the injection nozzle 18 changes due to the change. In this case, the cause of the change over time varies from cylinder to cylinder, and therefore the degree of change in injection characteristics varies from cylinder to cylinder.
[0028]
Incidentally, it is known that the spring of the injection nozzle 18 has a spring force that decreases in the initial stage of use and then stabilizes at a constant spring force, which is generally referred to as “initial change with time (or initial deterioration)”. Therefore, at the initial stage of use of the injection nozzle 18, it is conceivable that the injection characteristics change due to a decrease in spring force. On the other hand, the deposit formation of the nozzle injection hole portion occurs not only in the initial stage of use but in the entire use period, and the injection characteristics are changed by repeating the formation of the deposit → the separation.
[0029]
Therefore, in the present embodiment, a fuel injection control method is proposed in which stable injection characteristics (initially set injection characteristics) can be maintained regardless of changes over time of the injection nozzle 18 and the fuel injection pump 1.
[0030]
In short, the change in the injection characteristics accompanying the change with time appears in the rotation behavior of each cylinder, and the degree of change with time can be easily known for each cylinder by observing this rotation behavior. FIG. 3 shows the rotational behavior of each cylinder. (A) shows the rotational behavior at the time of factory shipment, that is, before the change with time, and (b) shows how the rotational behavior for each cylinder varies due to the change with time. In (a), the rotational behavior between the cylinders is almost the same at the time of factory shipment, that is, before the change with time is observed, but a slight variation in rotation between the cylinders is confirmed due to the engine-specific rotational fluctuation. The
[0031]
In such a case, the difference in rotational behavior between the cylinders shown in (b) is a result of reflecting changes over time with respect to each cylinder. In general, when the nozzle valve opening pressure decreases with time change, the fuel injection amount increases and the expansion stroke increases. The amount of rotation increase ΔNe # i (i represents the cylinder number) within a predetermined section at the time increases. However, as the instantaneous minimum rotational speed Nemin # i immediately before the expansion stroke is higher, the rotational increase amount ΔNe # i tends to be smaller even with the same injection amount.
[0032]
Further, FIG. 4 shows the relationship among the rotational increase amount ΔNe # i, the instantaneous minimum rotational speed Nemin # i, and the actual injection amount of each cylinder with the engine average rotational speed and the torque as constant conditions. According to FIG. 4, the rotation increase amount ΔNe # i and the instantaneous minimum rotation number Nemin # i are measured for each cylinder, and based on the ΔNe # i and Nemin # i, the injection nozzle 18 is actually used at that time. From this, the injection amount (actual injection amount) injected is obtained.
[0033]
In the present embodiment, for example, during idling when the engine operating state is stable, rotation information (ΔNe # i, Nemin # i) of each cylinder is detected, and the actual injection amount of the cylinder is estimated from the rotation information. Then, with reference to an initial state at the time of factory shipment or the like, a change over time is diagnosed for each cylinder from the degree of change in the actual injection amount from that state. At this time, the injection amount command value from the ECU 30 includes various correction terms such as an ISC correction term and a governor correction term in addition to the basic injection amount, and the actual injection amount includes the correction term. Presumed. Further, this correction term varies depending on the engine operating state at that time. Therefore, the correction term including the fluctuation element is removed from the actual injection amount, and as a result, the initial injection amount, the injection amount after change with time, and the “actual injection amount corresponding to the basic injection amount” are compared and determined.
[0034]
Next, how the fuel injection characteristics change when the nozzle valve opening pressure decreases with time, and how the injection characteristics change is eliminated in this embodiment will be described with reference to FIG. This will be described below. As described above, the end timing of pilot injection and the start timing and end timing of main injection are controlled by θ1, θ2, and θ3, respectively.
[0035]
As shown in FIG. 5A, when the nozzle valve opening pressure decreases due to a change over time, the valve opening period of the injection nozzle 18 becomes longer, and the injection amount during pilot injection and main injection increases. Actually, the injection amounts corresponding to ΔQp and ΔQm increase with respect to the injection amounts Qp1 and Qm1 before the change with time (initial time) indicated by hatching. Further, the interval between the pilot injection and the main injection (pilot interval) is narrowed.
[0036]
Therefore, as a measure for preventing a change in the injection characteristics, it is considered to correct the pilot injection end timing θ1, the main injection start timing θ2, and the main injection end timing θ3 by a predetermined amount to the advance side. Actually, as shown in FIG. 5 (b), the pilot injection end timing is advanced by Δθ1 and the main injection start timing θ2 is set to Δθ2 in accordance with the amount of change in the nozzle valve opening pressure, that is, the degree of change over time. The main injection end timing θ3 is advanced by Δθ3. By such correction, the injection amounts Qp2 and Qm2 at the time of pilot injection and main injection after correction indicated by hatching respectively coincide with the injection amounts Qp1 and Qm1 before change with time (initial time).
[0037]
Note that, when the area of the injection hole of the injection nozzle 18 is reduced by forming the deposit, the injection amount is reduced unlike FIG. In this case, θ1, θ2, and θ3 may be corrected to the retard side according to the degree.
[0038]
Next, the procedure for determining the amount of change with time and correcting the fuel injection according to the amount of change with time will be described with reference to the flowcharts of FIGS. The flowchart of FIG. 6 shows a time variation calculation routine, the flowchart of FIG. 7 shows an initial injection amount calculation routine, and the flowchart of FIG. 8 shows a fuel injection control routine. These routines are executed at predetermined time intervals by the CPU 31 in the ECU 30. To be implemented.
[0039]
Here, the temporal change amount ΔQ representing the degree of temporal change for each cylinder is the difference between the actual injection amount Qb estimated for each cylinder and the initial injection amount Qini which is the actual injection amount before the temporal change (initial state). Is required. That is, the actual injection amount Qb is calculated at the time of idling or the like by the routine of FIG. 6, and the initial injection amount Qini is calculated by the routine of FIG. 7 at the time of factory shipment or at the time of replacement of the injection nozzle. This will be described in detail below.
[0040]
When FIG. 6 starts, first, in step 101, it is determined whether or not an execution condition for calculating the temporal change amount ΔQ is satisfied. in this case,
・ During idle operation,
・ Issessment of ISC control (idle speed control)
If the execution condition is satisfied, the processing after step 102 is executed. Note that it is determined that the vehicle is idling when the accelerator is not operated. In addition, when the engine is in idle operation and the predetermined condition is further established, the condition for performing the ISC control is established. For example, when the accelerator operation is not performed immediately after the engine is started or during high-speed traveling, the conditions for performing ISC control are not satisfied even during idling.
[0041]
Thereafter, in step 102, values separately calculated for the rotational increase amount ΔNe # i and the instantaneous minimum rotational speed Nemin # i of the corresponding cylinder are read, and in the subsequent step 103, the read ΔNe # i and Nemin # i are read. Based on the above, the actual injection amount Qa of the corresponding cylinder is calculated. At this time, the actual injection amount Qa is calculated by referring to the map data obtained by quantifying the relationship shown in FIG. However, it is also possible to calculate the actual injection amount Qa with a function using the rotation increase amount ΔNe # i and the instantaneous minimum revolution number Nemin # i as parameters.
Qa = f (ΔNe # i, Nemin # i)
As a result, the actual injection amount Qa for each cylinder is calculated.
[0042]
In the following step 104, various corrections are subtracted from the calculated actual injection amount Qa to calculate an actual injection amount Qb corresponding to the basic injection amount. Finally, in step 105, the time variation ΔQ is calculated from the difference between the actual injection amount Qb corresponding to the basic injection amount and the initial injection amount Qini corresponding to the basic injection amount. To remember. In this case, cylinder discrimination is performed based on the cylinder discrimination signal, and the temporal change amount ΔQ is stored in the SRAM 34 in association with the cylinder number.
[0043]
In step 104, the actual injection amount Qb corresponding to the basic injection amount is calculated by subtracting the ISC correction amount and the governor correction amount from the actual injection amount Qa. In addition, the fuel during the operation of the air conditioner and the alternator is also calculated. Qb may be calculated by expecting the correction amount and subtracting the correction amount from the actual injection amount Qa.
[0044]
In the routine of FIG. 7, first, in step 201, it is determined whether or not the initial injection amount Qini before the change with time has already been calculated for all the cylinders. It is determined whether or not the initial injection amount Qini is to be calculated. For example, step 202 becomes YES immediately after replacement of the injection nozzle at the time of factory shipment or at a repair shop, and the processing after step 203 is performed.
[0045]
In step 203, the rotation increase amount ΔNe # i and the instantaneous minimum rotation number Nemin # i of the corresponding cylinder are read, and in the following step 204, based on ΔNe # i and Nemin # i, for example, using the relationship of FIG. The actual injection amount Qa of the corresponding cylinder is calculated. Since this actual injection amount Qa is a fuel injection amount including corrections such as ISC correction and governor correction, in the following step 205, various corrections are subtracted from the actual injection amount Qa to obtain an actual injection amount Qb corresponding to the basic injection amount. Is calculated. Finally, in step 206, the actual injection amount Qb corresponding to the basic injection amount is stored in the SRAM 34 separately for each cylinder as the initial injection amount Qini.
[0046]
On the other hand, in the fuel injection control routine of FIG. 8, in step 301, the engine operating state such as the engine speed, the accelerator opening, and the cooling water temperature is read, and in the subsequent step 302, the engine speed and The basic injection amount Qbse is calculated from the accelerator opening. Thereafter, in step 303, various corrections such as ISC correction and governor correction during idling are performed, and the fuel injection amount Qne is calculated. In step 304, a pilot injection command value and a main injection command value are calculated based on the calculated fuel injection amount Qne.
[0047]
Thereafter, in step 305, the temporal change amount ΔQ calculated in the processing of FIG. 6 is read from the SRAM 34, and in the subsequent step 306, injection correction values Δθ1, Δθ2, Δθ3 are calculated according to the temporal change amount ΔQ. The injection correction values Δθ1, Δθ2, and Δθ3 are correction values for correcting the pilot injection end timing θ1, the main injection start timing θ2, and the main injection end timing θ3 as described above (see FIG. For example, Δθi = Ki × f (ΔQ) is calculated (where i = 1, 2, 3). It should be noted that the f (ΔQ) term is set to a smaller value as the temporal change amount ΔQ increases. K1, K2, and K3 are injection amount correction coefficients, which are calculated according to the relationship of FIG. 9, for example. In this case, in FIGS. 9A, 9B, and 9C, the injection amount correction coefficients K1, K2, and K3 are set near 1 when idling, while the fuel injection amount Qne (engine load). And appropriately set according to the engine speed.
[0048]
Finally, at step 307, the pilot injection command value and the main injection command value (θ1, θ2, θ3 in FIG. 5) of step 304 are corrected by the calculated injection correction values Δθ1, Δθ2, Δθ3, and the corrected pilot is obtained. Fuel injection is performed based on the injection command value and the main injection command value.
[0049]
In the present embodiment, step 102 in FIG. 6 is the “rotation information acquisition means” of the present invention, steps 103 and 104 are “actual injection amount estimation means”, and step 105 is “time variation calculation means”. Each corresponds. Steps 306 and 307 in FIG. 8 correspond to “correction means”.
[0050]
According to the embodiment described in detail above, the following effects can be obtained.
Since the time variation ΔQ of the fuel injection device is calculated from the difference between the actual injection amount estimated for each cylinder and the pre-stored actual injection amount before the change with time, the engine-specific variation between cylinders is reduced. Even if there is, it is possible to determine the change over time while taking into account the variation. Further, even if the same change with time occurs in all the cylinders, it can be individually determined without canceling the change with time. As a result, it is possible to realize highly accurate temporal change determination.
[0051]
Further, the rotation increase amount ΔNe # i during the expansion stroke of each cylinder and the instantaneous minimum rotation number Nemin # i immediately before the expansion stroke are acquired as rotation information for each cylinder, and each cylinder is determined from this ΔNe # i and Nemin # i. The actual injection amount was estimated. In this case, by estimating the actual injection amount for each cylinder from the rotation increase amount ΔNe # i, the actual injection amount allows for the explosive force for each cylinder. Further, since the rotation increase amount ΔNe # i differs depending on the instantaneous minimum rotational speed Nemin # i, adding the instantaneous minimum rotational speed Nemin # i as a parameter makes the estimation result of the actual injection amount more accurate. Become. Therefore, it is possible to accurately estimate the actual injection amount for each cylinder by sufficiently considering the engine-specific rotation fluctuation characteristics for each cylinder. At this time, since the relationship of the actual injection amount with respect to ΔNe # i and Nemin # i has been quantified in advance (see FIG. 4), it is easy to estimate the actual injection amount.
[0052]
In addition, since the rotation information is acquired and the amount of change over time is calculated under the condition that the engine is in idle operation and the conditions for executing ISC control are satisfied, the change in the rotation behavior accompanying the change over time can be accurately grasped. Thus, it is possible to easily and accurately carry out the determination of the change with time.
[0053]
The actual injection amount corresponding to the basic injection amount is calculated for each cylinder by subtracting corrections such as ISC correction and governor correction from the actual injection amount (estimated value). Since the temporal change amount ΔQ of the fuel injection device is calculated by comparison with the initial injection amount Qini, it is possible to determine the temporal change with higher accuracy. In this case, the initial injection amount Qini is also calculated based on the rotation information for each cylinder, and is further calculated as an injection amount corresponding to the basic injection amount. This will take into account the variation between the two, improving the reliability of the determination of change over time.
[0054]
Further, by storing the change over time in the SRAM 34 (backup memory) for each cylinder and appropriately updating (learning) the backup value, the change over time of the fuel injection device can always be accurately grasped.
[0055]
Furthermore, since the fuel injection amount to each cylinder is corrected based on the temporal change amount ΔQ, it is possible to maintain the same injection characteristics as those before the temporal change even after the temporal change of the fuel injection device.
[0056]
In addition to the above, the present invention can be embodied in the following forms.
In the above embodiment, the rotation increase amount ΔNe # i during the expansion stroke of each cylinder and the instantaneous minimum rotation number Nemin # i immediately before the expansion stroke are acquired as rotation information for each cylinder, and this ΔNe # i and Nemin # i are acquired. Thus, the actual injection amount for each cylinder may be estimated using only the rotation increase amount ΔNe # i as the rotation information. In this case, the actual injection amount is estimated based on the rotation increase amount ΔNe # i using the relationship of FIG. Alternatively, the actual injection amount may be calculated using a function such as the actual injection amount = f (ΔNe # i).
[0057]
In the above-described embodiment, the cylinder discrimination is performed by the cylinder discrimination signal. However, the present apparatus can be realized even when there is no cylinder discrimination signal. That is, the initial value of the rotational fluctuation pattern for each cylinder is stored in the SRAM or the like at the time of factory shipment, and the previous data is updated each time using the rotational fluctuation pattern reflecting the change over time for each cylinder during subsequent engine operation. . In this case, since the change with time of each cylinder gradually occurs during the engine operation time, it is preferable to update the rotation fluctuation pattern when the engine is stopped (when the ignition is OFF). When determining the change with time, the cylinders are specified by comparing and referring to the rotation fluctuation pattern (SRAM data) for each cylinder up to the previous time and the current rotation fluctuation pattern, and the fuel injection command for each cylinder is further determined. Correct the value.
[0058]
In the above embodiment, the time-dependent change ΔQ is calculated on the condition that the engine is in idle operation and that the ISC control execution condition is satisfied. It is also good. Further, as the rotation information for each cylinder, the difference between the instantaneous minimum rotation speed and the maximum rotation speed in each cylinder may be used.
[0059]
In the above embodiment, an example of performing multi-stage injection has been described. Of course, the present invention is also effective when single injection is performed. Also in this case, highly accurate fuel injection control can be realized by performing correction according to the amount of change with time.
[0060]
In the above-described embodiment, the present invention is embodied as a fuel injection device including a distributed fuel injection pump and an injection nozzle. In addition, a high-pressure fuel pump, a common rail (accumulation chamber), and an electromagnetically driven injector are included. It is also possible to embody the present invention as a common rail fuel injection device. Even in such a case, the change with time of the fuel injection device can be accurately determined. In particular, in the common rail fuel injection device, a slight change with time of the injectors in each cylinder in order to inject high-pressure fuel appears remarkably as variations in injection characteristics. However, by applying the present invention, such problems can be solved.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing an overview of a fuel injection control system for a diesel engine in an embodiment of the invention.
FIG. 2 is a time chart for explaining a basic waveform of a fuel injection operation.
FIG. 3 is a diagram showing a rotational behavior for each cylinder.
FIG. 4 is a diagram illustrating a relationship among a rotation increase amount, an instantaneous minimum rotation number, and an actual injection amount.
FIG. 5 is a time chart for explaining a fuel injection mode at the time of change.
FIG. 6 is a flowchart showing a temporal variation calculation routine.
FIG. 7 is a flowchart showing an initial injection amount calculation routine.
FIG. 8 is a flowchart showing a fuel injection control routine.
FIG. 9 is a diagram for calculating an injection amount correction coefficient.
FIG. 10 is a diagram showing a relationship between a rotation increase amount and an actual injection amount.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Fuel injection pump, 4 ... Revolution sensor, 18 ... Injection nozzle, 30 ... ECU, 31 ... CPU, 34 ... SRAM.

Claims (9)

Applied to a fuel injection device comprising a fuel injection valve provided for each cylinder of a multi-cylinder engine and a pump device that is driven and controlled to pump fuel to the fuel injection valve,
Rotation information acquisition means for acquiring a rotation increase amount during an expansion stroke and an instantaneous minimum rotation speed immediately before the expansion stroke as rotation information for each cylinder;
Actual injection amount estimation means for estimating the actual injection amount actually injected from the fuel injection valve for each cylinder based on the acquired rotation increase amount and the instantaneous minimum rotation number ;
With time variation calculation means for calculating a temporal change amount of the fuel injection device by comparing the actual injection amount before aging stored in advance for each cylinder in this estimated actual injection quantity,
A time-dependent change determination apparatus for a fuel injection device. In the time-change determination apparatus of Claim 1,
Determining change over time of a fuel injection device that performs rotation information acquisition by the rotation information acquisition means and calculation of change over time by the change over time calculation means on condition that the engine is idling or in a steady stable state apparatus. In the time-change determination apparatus of Claim 1 ,
Determination of change over time of the fuel injection device that performs rotation information acquisition by the rotation information acquisition means and calculation of change over time by the change over time calculation means on condition that the number of revolutions during idling is controlled to a target value apparatus. In the time-dependent change determination apparatus as described in any one of Claims 1-3 ,
Various corrections are made to the basic injection amount set from the engine speed and load, and the final injection amount command value is determined.
The actual injection amount estimating means subtracts a correction amount according to the engine operating state from the estimated actual injection amount, and calculates an actual injection amount corresponding to the basic injection amount for each cylinder based on the result .
The time change calculation means calculates the change over time of the fuel injection device by comparing the calculated actual injection amount corresponding to the basic injection amount and a pre-stored actual injection amount corresponding to the basic injection amount before the change with time. A time-dependent change determination device for a fuel injection device that calculates an amount . In time course determination apparatus according to any one of claims 1-4,
A time-dependent change determination device for a fuel injection device that stores a time-dependent change amount of the fuel injection device calculated by the time-change-amount calculating means for each cylinder in a backup memory . In time course determination apparatus according to any one of claims 1 to 5,
When the initial condition considered to be before the change with time is established, the rotation information for each cylinder is acquired , the actual injection amount before the change with time is calculated for each cylinder based on the acquired rotation information , and the result is stored in the backup memory. The apparatus for determining change with time of the fuel injection device stored in In the time-change determination apparatus as described in any one of Claims 1-6,
An apparatus for determining change with time of a fuel injection device, further comprising: correction means for correcting the fuel injection amount into each cylinder based on the change with time of the fuel injection device calculated by the change with time calculation means. In the time-change determination apparatus as described in any one of Claims 1-7,
The fuel injection device includes a distribution type fuel injection pump as the pump device that increases the pressure of the fuel and distributes the high pressure fuel to each cylinder, and the high pressure fuel is pumped from the fuel injection pump, and at a predetermined valve opening pressure. An apparatus for determining change over time of a fuel injection device, comprising: an injection nozzle as the fuel injection valve that opens . In the time-change determination apparatus as described in any one of Claims 1-7,
The fuel injection device includes a high-pressure fuel pump as the pump device that increases the pressure of fuel, a common rail that stores high-pressure fuel pumped from the high-pressure fuel pump, and the fuel that injects high-pressure fuel in the common rail into each cylinder. A time-dependent change determination device for a fuel injection device, comprising an electromagnetically driven injector as an injection valve .

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