JP5115464B2 - Device for setting control parameters of internal combustion engine - Google Patents

Description

  The present invention relates to a control parameter setting device for an internal combustion engine.

  In an internal combustion engine such as a diesel engine, various regulations and standards are set for the amount of regulated substances (NOx and the like: hereinafter collectively referred to as “emission”), fuel consumption, and the like in exhaust gas. Therefore, it is necessary to set parameters for operation control of the internal combustion engine (hereinafter referred to as “control parameters”) so as to satisfy such regulations and standards.

  For example, when developing an internal combustion engine, an operation called calibration is performed. This conforming work generally involves fixing the rotational speed and load of an internal combustion engine (the load may be replaced by a fuel injection amount or torque) to a specific state, and in such a state, the target of regulation such as emission is a predetermined target. This is done by finding a combination of a plurality of control parameters (fuel injection timing, EGR valve opening, etc.) that satisfy the values.

  There is a demand for an internal combustion engine to reduce fuel consumption (fuel consumption) while suppressing emissions. However, there are many trade-offs between reducing emissions and reducing fuel consumption. For this reason, much labor and time have been required for the control parameter setting (adaptation) as described above.

  In view of this, devices that efficiently perform the adaptation work have been proposed (for example, Japanese Patent Application Laid-Open Nos. 2004-124935, 2005-299553, 2006-118515, and 2006). -170214 gazette, Unexamined-Japanese-Patent No. 2007-002677, etc.). Such an apparatus extracts the exhaust gas from the exhaust passage and analyzes the gas component, and adapts the control parameter so that the detected value of the gas component becomes the optimum value.

Specifically, first, an adaptation average value of control parameters of an existing (adapted) internal combustion engine having specifications corresponding to the specifications of the internal combustion engine that is the current adaptation target is set as an initial value. Next, a total amount target value in a predetermined operation mode (travel mode) and a target value for each operation state are determined as compatible target values such as an emission amount and fuel consumption. These target values are adapted values of the above-described existing internal combustion engine. Thereafter, the internal combustion engine is operated using the above-described initial values in each operation region. At this time, when the output value such as the emission amount or the fuel consumption exceeds the conforming target value, the control parameter is operated so as to decrease the output value.
JP 2004-124935 A JP 2005-299553 A JP 2006-118515 A JP 2006-170214 A JP 2007-002677 A

  There may be many control parameter setting results (conformance results) such that the emission amount and the fuel consumption are within the range of the target value or the regulation value. For this reason, the control parameter setting result by the conventional device of this type as described above is not always optimal in terms of fuel consumption. Therefore, according to this type of conventional apparatus, it has been extremely difficult to obtain a control parameter setting result (conformance result) that achieves the best fuel efficiency while satisfying the emission regulations.

  The present invention has been made to solve such problems. That is, an object of the present invention is to more easily obtain a control parameter setting result that achieves the best fuel efficiency while satisfying emission regulations.

<Configuration>
Features of the control parameter setting device (hereinafter simply referred to as “parameter setting device”) of the internal combustion engine of the present invention are as follows: NOx-fuel efficiency potential acquisition means, NOx generation rate target value setting means, And a control parameter determining means.

  The NOx-fuel efficiency potential acquisition means acquires the NOx-fuel efficiency potential for each of a plurality of conditions (regions) regarding the engine speed and the engine load. Here, the NOx-fuel consumption potential is the NOx generation rate of the lowest value of the fuel consumption rate on a plane having the NOx generation rate (= NOx generation amount per unit time unit output) and the fuel consumption rate as coordinate axes. Is defined as the change trajectory for.

  The NOx generation rate target value setting means is configured to reduce the total amount of NOx generated when the internal combustion engine is operated in accordance with the exhaust gas test measurement operation mode in the exhaust gas regulation of the internal combustion engine while keeping the total NOx generation amount below a predetermined total amount target value. A point on the NOx-fuel efficiency potential corresponding to each of the plurality of conditions is determined so as to minimize the amount. That is, the NOx generation rate target value setting means sets an individual target value that is a target value of the NOx generation rate under each of the plurality of conditions.

  The control parameter determination means determines the control parameter in each of the plurality of conditions based on the plurality of points determined by the NOx occurrence rate target value setting means.

  The NOx occurrence rate target value setting means may include an initial setting means, an update target determining means, and a NOx occurrence rate target value updating means as described below.

  The initial setting means sets an initial state of the point on the NOx-fuel economy potential corresponding to each of the plurality of conditions.

  The update target determining means has a minimum increase rate of the fuel consumption rate when the NOx generation rate at the point is reduced among the NOx-fuel economy potential corresponding to each of the plurality of conditions. It comes to decide.

  The NOx occurrence rate target value updating means moves the point on the NOx-fuel consumption potential determined by the update target determination means in a direction in which the NOx occurrence rate is reduced, thereby obtaining the NOx-fuel consumption potential. The individual target value of the NOx generation rate under the corresponding condition is updated.

<Action and effect>
In the parameter setting device of the present invention having the above-described configuration, first, the NOx-fuel efficiency potential is acquired for each of the plurality of conditions regarding the engine speed and the engine load. For example, if the range of engine speed and engine load that can be operated is divided into three stages, high load / high rotation, high load / medium rotation, high load / low rotation, medium load / high rotation, A total of nine conditions (regions) of low load and low rotation can be defined. In this case, the nine NOx-fuel efficiency potentials corresponding to the respective conditions are acquired by the NOx-fuel efficiency potential acquisition means.

  Next, the point on the NOx-fuel economy potential corresponding to each of the plurality of conditions is that the total amount of NOx generated when the internal combustion engine is operated according to the operation mode is less than the predetermined total amount target value. It is determined to minimize the fuel consumption. In the above-described example, the points in each of the nine NOx-fuel economy potentials corresponding to high load / high rotation or low load / low rotation indicate that the total amount of NOx generated is not more than the total amount target value and the fuel consumption amount. To be minimized.

  Specifically, this can be performed as follows, for example.

  First, the initial state of the point on the NOx-fuel economy potential corresponding to each of the plurality of conditions is set. For example, the initial state can be set so that the fuel consumption is less than a predetermined fuel efficiency target value. Specifically, as the initial state, the point on the side with the highest NOx generation rate (that is, the side with the lowest fuel consumption rate) in each of the NOx-fuel economy potentials corresponding to each of the plurality of conditions. Is set.

  Next, among the NOx-fuel efficiency potentials corresponding to each of the plurality of conditions, the gradient at the point (that is, the rate of increase in the fuel consumption rate when the NOx generation rate is reduced) is the smallest. It is determined.

  Subsequently, by moving the point on the NOx-fuel efficiency potential determined by the update target determining means in a direction in which the NOx occurrence rate decreases, the NOx in the condition corresponding to the NOx-fuel efficiency potential is moved. The individual target value of the occurrence rate is updated.

  As described above, by determining the plurality of points on the NOx-fuel efficiency potential, individual target values of the NOx generation rate under each of the plurality of conditions are set. Thereafter, the control parameter in each of the plurality of conditions is determined based on the determination result.

  Therefore, according to the present invention, it is possible to obtain a control parameter setting result (adaptation result) that achieves the best possible fuel efficiency while satisfying emission regulations more easily than in the past.

  Hereinafter, embodiments of the present invention (embodiments that the applicant considers best at the time of filing of the present application) will be described with reference to the drawings.

  In addition, the description about the following embodiment is specific to the extent possible, merely an example of the embodiment of the present invention in order to satisfy the description requirement (description requirement / practicability requirement) of the specification required by law. It is only what is described in. Therefore, as will be described later, it is quite natural that the present invention is not limited to the specific configurations of the embodiments described below. Various modifications that can be made to the present embodiment are listed together at the end, as they would interfere with the understanding of the consistent description of the embodiment if inserted during the description of the embodiment. .

<Overall system configuration>
FIG. 1 is a schematic diagram showing an overall configuration of a system 1 to which an embodiment of the present invention is applied. Referring to FIG. 1, a system 1 in this embodiment is a bench test system for setting control parameters of an engine 2, and includes an engine 2, a fuel injection device 3, an intake / exhaust device 4, and the present invention. And a control device 5 as a parameter setting device.

  The engine 2 of this embodiment is a diesel engine as a compression ignition engine. In the present embodiment, the engine 2 has a plurality (four in FIG. 1) of combustion chambers 21 arranged in series.

<Fuel injection device>
The fuel injection device 3 includes the same number of injectors 31 as the combustion chambers 21. That is, each injector 31 is arranged so as to correspond to each combustion chamber 21. The injector 31 of the present embodiment has a known piezo-type configuration, and is configured so that fuel can be directly injected into the combustion chamber 21.

  The fuel injection device 3 of this embodiment is a well-known common rail type fuel injection device, and each injector 31 is connected to a common rail 32 via a fuel supply pipe 33. A fuel pump 36 is interposed in the fuel supply passage 35 between the common rail 32 and the fuel tank 34.

<Intake and exhaust device>
The intake manifold 41 is mounted on the engine 2 so that air (including exhaust gas recirculated) can be supplied to each combustion chamber 21. The intake manifold 41 is connected to an air cleaner 42 via an intake pipe 43. A throttle 44 is interposed in the intake pipe 43. The throttle 44 is driven by a throttle actuator 44a composed of a stepping motor or the like.

  The exhaust manifold 45 is attached to the engine 2 so as to receive the exhaust gas from each combustion chamber 21. The exhaust manifold 45 is connected to the exhaust pipe 46.

  A turbocharger 47 is interposed between the intake pipe 43 and the exhaust pipe 46. That is, the intake pipe 43 is connected to the compressor 47 a side of the turbocharger 47, and the exhaust pipe 46 is connected to the turbine 47 b side of the turbocharger 47.

  The turbocharger 47 in this embodiment is of a so-called variable nozzle type. That is, a movable vane nozzle 47b2 is provided at a position facing the turbine rotor 47b1. The vane nozzle 47b2 is driven by a vane nozzle actuator 47b3.

  An EGR (Exhaust Gas Recirculation) device 48 is interposed between the intake manifold 41 and the exhaust manifold 45. The EGR device 48 includes an EGR passage 48a, an EGR valve 48b, and an EGR valve actuator 48c.

  The EGR passage 48 a is a passage for EGR gas (recirculation exhaust gas), and is provided so as to connect the intake manifold 41 and the exhaust manifold 45. An EGR valve 48b is interposed in the EGR passage 48a. The EGR valve 48b is driven by an EGR valve actuator 48c to control the supply amount (EGR rate) of EGR gas to the intake manifold 41.

<Control device>
The control device 5 controls the operation of the system 1 including the engine 2, the fuel injection device 3, and the intake / exhaust device 4. The control device 5 constitutes NOx-fuel efficiency potential acquisition means, NOx generation rate target value setting means, control parameter determination means, initial setting means, update target determination means, and NOx generation rate target value update means of the present invention. An electronic control unit (ECU) 50 is provided.

  The ECU 50 includes a CPU (microprocessor) 50a, a ROM (read only memory) 50b, a RAM (random access memory) 50c, a backup RAM 50d, an interface 50e, and a bus 50f. The CPU 50a, ROM 50b, RAM 50c, backup RAM 50d, and interface 50e are connected to each other by a bus 50f.

  The CPU 50 a is configured to execute a routine (program) for controlling the operation of each unit in the system 1. In the ROM 51b, routines executed by the CPU 50a, tables (look-up tables, maps), parameters, and the like are stored in advance. The RAM 50c is configured to temporarily store data as necessary when the CPU 50a executes a routine. The backup RAM 50d is configured to store data when the CPU 50a executes a routine while the power is turned on, and to store the stored data even after the power is turned off.

  The interface 50e is electrically connected to various sensors described later, and is configured to transmit detection signals from these sensors to the CPU 50a. The interface 50e is electrically connected to operating parts such as the injector 31, the fuel pump 36, the throttle actuator 44a, the vane nozzle actuator 47b3, and the EGR valve actuator 48c, and the operation for operating these operating parts. A signal can be transmitted from the CPU 50a to these operating units. That is, the control device 5 receives the detection signal from each of the sensors described above via the interface 50e, and sends the operation signal to each operation unit based on the calculation result of the CPU 50a corresponding to the detection signal. It is configured.

  The air flow meter 51 is interposed in the intake pipe 43 on the downstream side of the compressor 47 a of the turbocharger 47. The air flow meter 51 is configured to generate an output voltage corresponding to a mass flow rate per unit time of intake air flowing through the intake pipe 43.

  The exhaust gas sensor 52 is interposed in the exhaust pipe 46 on the downstream side of the turbine 47 b of the turbocharger 47. The exhaust gas sensor 52 is configured to generate an output voltage corresponding to the concentration of each component (NOx or the like) in the exhaust gas.

  A rail pressure sensor 53 is interposed in the common rail 32. The rail pressure sensor 53 is configured to generate an output voltage corresponding to the pressure in the common rail 32. In addition, a fuel flow sensor 54 is interposed in the fuel supply passage 35. The fuel flow rate sensor 54 is configured to generate an output voltage corresponding to the flow rate of fuel flowing through the fuel supply passage 35.

  The crank angle sensor 55 outputs a narrow pulse every time a crankshaft (not shown) of the engine 2 rotates a predetermined angle (for example, 10 °), and a wide pulse every time the crankshaft rotates 360 °. Is configured to output.

  The accelerator opening sensor 56 is configured to generate an output voltage corresponding to the operation amount (depression amount) of the accelerator pedal 56a operated by the driver.

  The interface 50e is electrically connected to the dynamometer 57. The dynamometer 57 is connected to a crankshaft (not shown) of the engine 2 and adjusts the load of the engine 2.

<Outline of Control Parameter Setting Operation According to Configuration of Embodiment>
Next, the outline of the control parameter setting operation of the engine 2 by the system 1 of the present embodiment will be described.

  The engine 2 of this embodiment is a diesel engine as a compression ignition engine. As the NOx emission reduction means in the engine 2, in this embodiment, EGR or the retard of the fuel injection timing is used. However, the fuel consumption rate deteriorates due to a decrease in combustion speed and isovolume due to these. That is, the NOx emission amount and the fuel consumption rate are in a trade-off relationship.

  By the way, exhaust gas regulations such as NOx emission amount are performed based on the total discharge weight (or discharge weight per unit distance travel) in the operation mode (vehicle travel mode) such as the 10.15 mode and the diesel 13 mode. However, the characteristics of the emission amount and the fuel consumption rate vary depending on the rotation region and the load region. Therefore, the control parameter setting operation is performed so that the individual target value of the emission amount such as the NOx emission amount is assigned to each rotation / load region, and the integrated value is within the regulation value and the fuel consumption is within the predetermined range. Done.

<< NOx-Acquisition of fuel economy potential >>
FIG. 2 is a graph conceptually showing the relationship between the NOx generation rate and the fuel consumption rate for each rotation / load region (in FIG. 2, the rotation / load region is divided into four for convenience of illustration). However, such illustrations are not intended to limit the invention to such contents).

  As shown in FIG. 2, there are various allocation patterns of individual target values of NOx emissions that satisfy the NOx emissions regulations and target fuel consumption in a predetermined operation mode (for example, in the figure). Circle symbol combinations, triangle symbol combinations, x symbol combinations, etc.). Here, if the combination of the circle symbols in the figure is a combination that optimizes both the NOx emission amount and the fuel consumption, it is extremely difficult to search for this reliably. Therefore, according to the conventional method and apparatus, the allocation pattern of the individual target value of the NOx emission amount is usually a combination of triangular symbols or a combination of X symbols in the figure.

  On the other hand, in the present embodiment, first, NOx-fuel economy potential is acquired for a plurality of rotation / load regions. This NOx-fuel efficiency potential is defined as a change locus of the minimum value of the NOx generation rate with respect to the fuel consumption rate on a plane having the fuel consumption rate and the NOx generation rate as coordinate axes (see the curve in the figure). Each point in the figure represents a fuel that can be realized when the engine 2 is operated using a number of combinations of control parameters (such as the opening degree of the EGR valve 48b and the vane nozzle 47b2) in each rotation / load region. The consumption rate and the NOx generation rate shall be indicated.

  In the present embodiment, the NOx-fuel efficiency potential is acquired as follows.

  EGR has the greatest effect (sensitivity) as a factor for reducing the amount of NOx generated, and the next is the delay of the fuel injection timing. On the other hand, regarding the deterioration of fuel consumption, the influence of retarding the fuel injection timing is larger than that of EGR. The greatest influence on EGR is the opening of the EGR valve 48b, the opening of the vane nozzle 47b2 is the next, and the opening of the throttle 44 is the next.

  Therefore, when obtaining the NOx-fuel efficiency potential of the present embodiment, after setting an initial state in which the amount of NOx generated is large and the fuel efficiency is extremely good, the control parameter is first operated in the direction of increasing the EGR, and then the fuel injection is performed. Time is manipulated. At this time, the priority order of the EGR increase operation is (1) EGR valve 48b, (2) vane nozzle 47b2, and (3) throttle 44. However, when the excess air ratio λ becomes less than the smoke limit x, the priority order of the EGR valve 48b and the vane nozzle 47b2 is changed because of the need to introduce fresh air.

  According to such a procedure, the NOx-fuel efficiency potential acquisition process can be performed automatically and more efficiently.

<< NOx-Determination of NOx generation rate individual target value using fuel efficiency potential >>
Using the NOx-fuel efficiency potential acquired as described above, control parameters are set such that the contradiction between the NOx emission amount and the fuel efficiency is reduced.

  That is, as shown in FIG. 2, the NOx-fuel efficiency potential in each rotation / load region is the minimum fuel consumption rate when the NOx generation rate is constant, or the minimum when the fuel consumption rate is constant. It becomes a curve showing the NOx generation rate. Therefore, by allocating the NOx generation amount target value and the fuel consumption rate target value so as to be points on the NOx-fuel efficiency potential in each rotation / load region, there is less contradiction between the NOx emission amount and the fuel efficiency. A control parameter setting result is obtained.

  Specifically, first, in each rotation / load region, the point on the NOx-fuel consumption potential on the side where the NOx generation rate is the highest (right side in FIG. 2: the fuel consumption becomes the best as a trade-off at this time) Set as initial value.

  Next, the NOx-fuel consumption potential is such that the gradient at each point (the absolute value thereof) is minimum, that is, the increase rate of the fuel consumption rate is minimized when the NOx generation rate is reduced by a predetermined amount from the current target value. Is determined (searched).

  Subsequently, in the rotation / load region corresponding to the determined (searched) NOx-fuel efficiency potential, the NOx occurrence rate is reduced from the current target value (on the left side in FIG. 2) on the NOx-fuel efficiency potential. The point is moved a predetermined amount.

  Such an operation is repeated until the NOx emission amount satisfies the regulation value. Thereby, the NOx generation rate individual target value in each rotation / load region is assigned so that both the NOx emission amount and the fuel consumption are optimized. Based on this, a control parameter setting result that optimizes both the NOx emission amount and the fuel consumption can be obtained reliably and easily.

<Specific Example of Control Parameter Setting Operation According to Configuration of Embodiment>
Next, one specific example of the control parameter setting operation of the engine 2 by the system 1 of the present embodiment will be described using a flowchart. In the flowchart of each figure, “step” is abbreviated as “S”.

<< NOx-Fuel consumption potential acquisition >>
3 to 6 are flowcharts showing a specific example of the NOx-fuel efficiency potential acquisition routine by the control device 5 of the present embodiment shown in FIG. In this embodiment, the NOx-fuel efficiency potential acquisition means of the present invention is realized by execution of the routine 300 by the ECU 50 (CPU 50a).

  This routine 300 is executed one by one for NOx-fuel efficiency potential acquisition corresponding to a certain rotation / load region. That is, when the rotation / load region is divided into nine, the routine 300 is executed a total of nine times corresponding to each rotation / load region. Accordingly, nine NOx-fuel economy potentials are acquired corresponding to each rotation / load region. At this time, it is assumed that the operation of the engine 2 is controlled so that the engine speed and the load are constant during the NOx-fuel efficiency potential acquisition by the execution of the routine 300.

The initial conditions in the NOx-fuel efficiency potential acquisition operation are as follows.
EGR valve 48b: Fully closed Vane nozzle 47b2: Optimum fuel economy opening determined by the specifications of the turbocharger 47 and rotation / load conditions Throttle 44: Fully open Fuel injection timing: MBT (Injection timing with the largest generated torque)

  When the routine 300 is started, first, at step 310, it is determined whether or not the excess air ratio λ is larger than a predetermined smoke limit x. Here, the excess air ratio λ is obtained from the output of the air flow meter 51, the opening degree of the EGR valve 48b, and the fuel injection amount (command fuel injection time calculated by the ECU 50 by well-known air-fuel ratio feedback control). .

  When the excess air ratio λ is equal to or less than the smoke limit x (step 310 = No), the processing after step 320 (operation of the EGR valve 48b) is skipped, and the processing proceeds to the flow of FIG. 4 (operation of the vane nozzle 47b2). (Refer to (2) in the figure: above-mentioned priority change). On the other hand, when the excess air ratio λ is larger than the smoke limit x (step 310 = Yes), the process proceeds from step 320 onward.

  In step 320, it is determined whether or not the EGR valve 48b is fully open. Under the above-described initial conditions, the EGR valve 48b is fully closed (step 320 = No), so the process proceeds from step 330 onward. If the determination in step 320 is “Yes”, the processing after step 330 is skipped, and the processing proceeds to the flow of FIG. 4 (see (2) in the figure).

  In step 330, the EGR valve 48b is opened by one step (at this time, the opening degree of the vane nozzle 47b2 is set to the above-described optimum fuel economy opening degree). Here, “one step” means the minimum unit of the drive amount of the EGR valve actuator 48c when the opening degree of the EGR valve 48b is adjusted (changed). Next, the process proceeds to step 340, and it is determined again whether or not the excess air ratio λ is larger than the smoke limit x.

  When the excess air ratio λ is larger than the smoke limit x (step 340 = Yes), the process proceeds to step 350, and the fuel injection timing is set to MBT. Subsequently, at step 360, the NOx generation rate and the fuel consumption rate are measured, and the process returns to the first step of the routine 300 again. Note that the NOx generation rate is acquired based on the output of the exhaust gas sensor 52. The fuel consumption rate is acquired based on the outputs of the rail pressure sensor 53 and the fuel flow sensor 54 and the energization time to the injector 31.

  When the excess air ratio λ is equal to or less than the smoke limit x (step 340 = No), the process proceeds to step 370, and the immediately preceding operation is returned. That is, the EGR valve 48b is closed for one step. Thereafter, the processing proceeds in the same manner as in the case where the determination in step 310 is “No” and the determination in step 320 is “Yes” (see (2) in the figure).

  When the process proceeds to the flow of FIG. 4 (see (2) in the upper part of the figure), in step 410, it is determined whether or not the vane nozzle 47b2 is fully opened. Under the above-mentioned initial conditions, the opening degree of the vane nozzle 47b2 is the above-described optimum fuel economy opening degree (step 410 = No), and thus the process proceeds to step 420 and thereafter. When the determination in step 410 is “Yes”, the processing after step 420 is skipped, and the processing proceeds to the flow of FIG. 5 (operation of the throttle 44) (see (3) in the drawing).

  In step 420, the vane nozzle 47b2 is closed for one step. Here, “one step” means the minimum unit of the driving amount of the vane nozzle actuator 47b3 when the opening degree of the vane nozzle 47b2 is adjusted (changed).

  Next, the process proceeds to step 430, and it is determined again whether or not the excess air ratio λ is larger than the smoke limit x. When the excess air ratio λ is larger than the smoke limit x (step 430 = Yes), the process proceeds to step 440, and the fuel injection timing is set to MBT. Subsequently, at step 450, the NOx generation rate and the fuel consumption rate are measured, and the process returns to the first step of the routine 300 again.

  When the excess air ratio λ is equal to or less than the smoke limit x (step 430 = No), the process proceeds to step 460, and the opening degree of the EGR valve 48b is set so that the excess air ratio λ becomes equal to the smoke limit x. The Next, the process proceeds to step 470, and it is determined based on the output of the exhaust gas sensor 52 whether or not the oxygen concentration is lower than at the previous measurement.

  If the oxygen concentration is lower than the previous measurement (step 470 = Yes), the process proceeds to steps 440 and 450, the NOx generation rate and the fuel consumption rate are measured, and the process is again the first step of the routine 300. Return. If the oxygen concentration is not lower than the previous measurement (step 470 = No), the process proceeds to step 480, the fuel injection timing is set to MBT, and the process returns to step 410.

  When the process proceeds to the flow of FIG. 5 (see (3) in the figure), it is determined in step 510 whether or not the throttle 44 is fully closed. Under the above-described initial conditions, the throttle 44 is fully open (step 510 = No), so the process proceeds from step 520 onward. When the determination in step 510 is “Yes”, it is estimated that the throttle 44 is accidentally fully closed due to an abnormality in the throttle control system such as the throttle actuator 44a. Therefore, in this case, the processing after step 520 is skipped, abnormality processing is performed, and this routine ends.

  In step 520, the throttle 44 is closed by one step. Next, the process proceeds to step 530, and it is determined again whether the excess air ratio λ is larger than the smoke limit x.

  When the excess air ratio λ is larger than the smoke limit x (step 530 = Yes), the process proceeds to steps 540 and 550, and the NOx generation rate and the fuel consumption rate are measured after the fuel injection timing is set to MBT. The process returns to the first step of the routine 300 again.

  When the excess air ratio λ is equal to or less than the smoke limit x (step 530 = No), the process proceeds to step 560, and the immediately preceding operation is returned. That is, the throttle 44 is opened for one step. Thereafter, the process proceeds to the flow of FIG. 6 (fuel injection timing operation) (see (4) in the figure).

  When the process proceeds to the flow of FIG. 6 (see (4) in the figure), in step 610, it is determined whether or not the misfire margin y is less than “predetermined value y0 + 1 steps”. Here, the misfire margin means the deviation of the current fuel injection (main injection) timing from the misfire limit timing (the most retarded main injection timing within a range where no misfire occurs) toward the advance side. Shall. Further, “one step” means a minimum unit for adjusting (changing) the fuel injection timing.

  If the misfire margin is sufficient, that is, if y is greater than or equal to “predetermined value y0 + 1 step” (step 610 = No), the process proceeds to step 620 and the fuel injection timing is delayed by one step, and thereafter In step 630, the NOx generation rate and the fuel consumption rate are measured, and the process returns to the first step of the routine 300 again. On the other hand, when y is less than “predetermined value y0 + 1 step” (step 610 = Yes), this routine ends. At this time, the NOx-fuel efficiency potential acquisition process in a certain rotation / load region (rotation / load condition) ends.

<< NOx-Determination of NOx generation rate individual target value using fuel efficiency potential >>
FIG. 7 is a flowchart showing a specific example of a routine for determining (allocating) the NOx generation rate individual target value by the control device 5 of the present embodiment shown in FIG.

In addition, the meaning of each symbol in the following description is as follows.
d _k : Frequency during operation mode of the k-th rotation / load region [kWh]
= Time during the predetermined operation mode in the k-th rotation / load region [h]
× Work required from engine speed and load [kW]
x _k : Individual target value [g / kWh] of the NOx generation rate in the k-th rotation / load region
QNOx_t: mode total NOx amount (total NOx generation amount in a predetermined operation mode)
= Σd _k x _k
A: Total amount target value of NOx generation amount in a predetermined operation mode [g]
f _k : NOx-fuel efficiency potential [g / kWh] in the k-th rotation / load region
X = (x ₁ , x ₂ ,..., X _n )
g (X): Mode total fuel consumption potential function [g]
= Σd _k f _k (x _k )

When the routine 700 is started, first, in step 710, initial values of x ₁ , x ₂ ,..., X _n are set so that the size of the vector X is maximized. That is, the point on the NOx-fuel consumption potential on the side where the NOx generation rate is the highest in each rotation / load region (the right side in FIG. 2: the fuel consumption becomes the best as a trade-off at this time) is set as the initial state. .

Next, at step 720, it is determined whether or not the mode total NOx amount (QNOx_t) is greater than a predetermined value A. In the processing start after the first routine, the determination of step 720 is "Yes", NOx-fuel potential of the processing proceeds to step _{730, x 1, x 2,} ···, x n gradient (tangent slope) of the absolute value of the minimum point, i.e., the NOx- fuel potential f _k as the increase rate of the fuel consumption rate becomes the minimum when the NOx generation rate x _k is reduced a predetermined amount, Searched (determined).

Subsequently, at step 740, the individual target value x _k of the NOx generation rate in the searched k-th rotation and the load regions can be increased a predetermined amount. Thereafter, the process returns to step 720.

Step 720 without the above that the process of 740 is repeated, under the condition that the combination of the individual target value x _k and the fuel consumption rate of NOx generation rate of each rotation and load region is a point on the NOx- fuel potential The mode total NOx amount is gradually decreased while preventing the fuel consumption from being deteriorated as much as possible.

Thereafter, when the determination result at step 720 turns to “No”, the process proceeds to step 750. In step 750, based on the point on the NOx- fuel potential in each rotation-load region determined (assignment of individual target value x _k of the NOx generation rate) control parameters in each rotation-load region (EGR valve opening Degree, VN opening, throttle opening, fuel injection timing, etc.) are set. Then, the processing of this routine ends.

According to the processing of the routine 700, determination of a point on the NOx-fuel consumption potential in each rotation / load region so as to optimize the fuel consumption while satisfying the total NOx generation target value A in the predetermined operation mode, that is, assignment of the individual target value _{x k} of the NOx generation rate is performed.

  Then, based on the point on the NOx-fuel consumption potential determined in this way, control parameters in each rotation / load region are set. Therefore, according to the processing of this routine 700, a control parameter setting result that optimizes both the NOx emission amount and the fuel consumption can be obtained reliably and easily.

  In the present embodiment, it is assumed that the NOx generation rate target value setting means of the present invention is realized by execution of the routine 700 by the ECU 50 (CPU 50a). Similarly, the initial setting means of the present invention is realized by the processing in step 710. Further, the update target determining means of the present invention is realized by the processing of step 730. Further, the NOx generation rate target value updating means of the present invention is realized by the processing of step 740. Further, the control parameter determining means of the present invention is realized by the processing of step 750.

<List of examples of modification>
Note that, as described above, the above-described embodiments are merely examples of typical embodiments of the present invention that the applicant has considered to be the best at the time of filing of the present application. Therefore, the present invention is not limited to the above-described embodiment.

  Therefore, it goes without saying that various modifications can be made to the above-described embodiment within the scope not changing the essential part of the present invention.

  Hereinafter, some typical modifications will be exemplified. However, it goes without saying that the modifications are not limited to those listed below. In addition, a plurality of modified examples can be applied in a composite manner as appropriate within a technically consistent range.

  The present invention (especially those expressed functionally and functionally in the constituent elements constituting the means for solving the problems of the present invention) is based on the above-described embodiment and the description of the following modifications. Should not be interpreted as limited. Such a limited interpretation is unacceptable and improper for imitators, while improperly harming the applicant's interests (rushing to file under a prior application principle).

  (A) The present invention is not limited to the specific apparatus configuration disclosed in the above embodiment.

  For example, the system 1 may be a machine (vehicle or the like) on which the engine 2 is mounted. That is, the control parameter setting operation of the present invention can be performed in a bench test system or can be performed in a machine-mounted (on-vehicle) state. Moreover, it can be performed at the time of engine development (at the time of conforming work), and can also be performed at the time of a pre-shipment test and a post-shipment inspection of the production engine and production vehicle.

  Further, there is no particular limitation on the number of cylinders and the cylinder arrangement method.

  Furthermore, the present invention can be applied even if the turbocharger 47 is not variable or without the turbocharger 47. Similarly, the present invention can be applied without the throttle 44.

  (B) The present invention is not limited to the specific processing disclosed in the above embodiment.

  For example, the NOx-fuel consumption potential may be acquired not by automatic acquisition by the control device 5 as in the above embodiment (see the flowcharts in FIGS. 3 to 6) but by manual acquisition using an experimental design method or the like.

In addition, the initial values of x ₁ , x ₂ ,..., X _n are set so that the total mode fuel consumption is less than a predetermined fuel consumption target value even if the magnitude of the vector X is not maximized. Can be done.

  (C) Other modifications not specifically mentioned are naturally included in the scope of the present invention as long as they do not change the essential part of the present invention.

  In addition, in each element constituting the means for solving the problems of the present invention, elements expressed functionally and functionally include the specific structures disclosed in the above-described embodiments and modifications, It includes any structure that can realize this action / function. Furthermore, the contents (including the specification and drawings) of each publication cited in the present specification may be incorporated as part of the specification.

1 is a schematic diagram illustrating an overall configuration of a system to which an embodiment of the present invention is applied. It is a graph which shows notionally the relationship between the NOx generation rate and the fuel consumption rate for each rotation / load region. It is a flowchart which shows a specific example of the NOx-fuel-consumption potential acquisition routine by the control apparatus of this embodiment shown by FIG. FIG. 4 is a flowchart showing a specific example of a NOx-fuel efficiency potential acquisition routine by the control device of the present embodiment shown in FIG. 1 (FIG. 4 shows a continuation of the flow of FIG. 3). FIG. 5 is a flowchart showing a specific example of a NOx-fuel efficiency potential acquisition routine by the control device of the present embodiment shown in FIG. 1 (FIG. 5 shows a continuation of the flow of FIG. 4). FIG. 6 is a flowchart showing a specific example of a NOx-fuel efficiency potential acquisition routine by the control device of the present embodiment shown in FIG. 1 (FIG. 6 shows a continuation of the flow of FIG. 5). 2 is a flowchart showing a specific example of a routine for determining (allocating) a NOx generation rate individual target value by the control device of the present embodiment shown in FIG. 1.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... System 2 ... Engine 21 ... Combustion chamber 3 ... Fuel injection device 31 ... Injector 32 ... Common rail 4 ... Intake / exhaust device 44 ... Throttle 44a ... Throttle actuator 47 ... Turbocharger 47b2 ... Vane nozzle 47b3 ... VN actuator 48 ... EGR device 48b ... EGR valve 48c ... EGR valve actuator 5 ... control device 50 ... ECU 50a ... CPU
DESCRIPTION OF SYMBOLS 51 ... Air flow meter 52 ... Exhaust gas sensor 53 ... Rail pressure sensor 54 ... Fuel flow sensor 55 ... Crank angle sensor 57 ... Dynamometer

Claims (2)

A control parameter setting device for an internal combustion engine,
NOx-fuel efficiency potential defined as a change locus with respect to the NOx generation rate of the minimum value of the fuel consumption rate on a plane having the NOx generation rate and the fuel consumption rate as coordinate axes as the NOx generation amount per unit time unit output, NOx-fuel efficiency potential acquisition means for acquiring a plurality of conditions for the engine speed and engine load;
A plurality of NOx generation amounts when the internal combustion engine is operated according to the exhaust gas test measurement operation mode in the exhaust gas regulations of the internal combustion engine are set to be equal to or less than a predetermined total amount target value while minimizing fuel consumption. NOx generation rate target value setting means for setting an individual target value of the NOx generation rate in each of the plurality of conditions by determining a point on the NOx-fuel economy potential corresponding to each of the conditions;
Control parameter determining means for determining the control parameter in each of the plurality of conditions based on the plurality of points determined by the NOx occurrence rate target value setting means;
A control parameter setting device for an internal combustion engine, comprising: A control parameter setting device for an internal combustion engine according to claim 1,
The NOx occurrence rate target value setting means includes:
Initial setting means for setting an initial state of the point on the NOx-fuel economy potential corresponding to each of a plurality of the conditions;
Update target determination means for determining the NOx-fuel economy potential corresponding to each of the plurality of conditions that has the smallest increase rate of the fuel consumption rate when the NOx generation rate at the point is reduced When,
By moving the point on the NOx-fuel consumption potential determined by the update target determining means in a direction in which the NOx generation rate is reduced, the NOx generation rate in the condition corresponding to the NOx-fuel consumption potential is increased. NOx occurrence rate target value updating means for updating the individual target value;
A control parameter setting device for an internal combustion engine, comprising:

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