JP4582010B2 - Fuel injection control device - Google Patents

Description

  The present invention detects a fuel pressure in a pressure accumulating chamber, a fuel pump that pumps fuel into the pressure accumulating chamber, a fuel injection valve that injects fuel stored in the pressure accumulating chamber, and a fuel pressure in the pressure accumulating chamber. The present invention relates to a fuel injection control device that is applied to a fuel injection device of an internal combustion engine that includes a detection unit and that operates the fuel pump to feedback control the fuel pressure detected by the detection unit to a target value.

  2. Description of the Related Art A fuel injection device including a common pressure accumulation chamber (common rail) that supplies high-pressure fuel to a fuel injection valve of each cylinder of a diesel engine is well known. According to the common rail type diesel engine, the fuel pressure in the common rail can be freely controlled according to the engine operating state, and as a result, the pressure of the fuel supplied to the fuel injection valve can be freely controlled.

  On the other hand, a fuel injection control device of a diesel engine usually operates a fuel pump so as to feedback control the detected value of the fuel pressure in the common rail to a target value. At this time, the target value is set according to the rotational speed of the output shaft of the diesel engine and the operation amount of the accelerator pedal (Patent Document 1). By setting the target value according to the operation amount of the accelerator pedal and the rotational speed, it is possible to inject the fuel of the required injection amount within a period appropriate for fuel injection.

However, even if the target value is set in the above mode, the inventors have found that deterioration of exhaust characteristics becomes a problem in a transient state, for example, when the operation amount of the accelerator pedal changes suddenly. Has been issued. This is because when the target value is set in the above-described manner, the fuel pressure in the common rail in the transient state is only controlled by feedback control so as to follow the target value that changes abruptly. This is probably because proper fuel pressure control is not necessarily performed to suppress the deterioration of fuel.
JP 2873133 A

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a fuel injection control device capable of suppressing deterioration of exhaust characteristics even when the target value of fuel pressure is changed. There is to do.

  Hereinafter, means for solving the above-described problems and the operation and effects thereof will be described.

According to a first aspect of the present invention, the fuel pump is provided with power from the output shaft of the internal combustion engine, and storage means for storing information relating to a relational expression that defines the change in the target value as a function of time; And a setting means for setting a target value of the feedback control based on the relational expression , wherein the relational expression is a region divided by at least one of the operation amount of the accelerator operating member and the command value of the injection amount for the fuel injection valve. It is characterized by being provided separately for each.

In the above configuration, the fuel pressure is feedback-controlled using a relational expression that defines a change in the target value as a function of time. For this reason, by adapting the relational expression so as to suppress the deterioration of the exhaust characteristics, it is possible to suppress the deterioration of the exhaust characteristics even when the target value is changed.
Furthermore, in the above configuration, by using different relational expressions for each region, it is possible to use a relational expression that is more appropriately adapted to suppress the deterioration of exhaust characteristics.
According to a second aspect of the present invention, the fuel pump is powered by the output shaft of the internal combustion engine, and storage means for storing information relating to a relational expression that defines the change in the target value as a function of time; Setting means for setting the target value of the feedback control based on the relational expression, and the value of the setting parameter, which is a parameter for determining the relational expression, is a command for the operation amount of the accelerator operation member and the injection amount for the fuel injection valve Each region is divided according to at least one of the values.
In the above configuration, the fuel pressure is feedback-controlled using a relational expression that defines a change in the target value as a function of time. For this reason, by adapting the relational expression so as to suppress the deterioration of the exhaust characteristics, it is possible to suppress the deterioration of the exhaust characteristics even when the target value is changed.
Furthermore, in the above configuration, by setting the value of the setting parameter to a different value for each region, it is possible to use a relational expression that is more appropriately adapted to suppress the deterioration of exhaust characteristics.

A third aspect of the invention is based on at least one of the rotational speed of the output shaft of the internal combustion engine, the operation amount of the accelerator operation member, and the command value of the injection amount for the fuel injection valve in the invention of the first or second aspect. And determining means for determining whether there is a change request for the target value, wherein the setting means changes the target value based on the relational expression when it is determined that there is the change request. .

  In the above configuration, it is possible to appropriately determine the target value change request based on the rotation speed of the output shaft of the internal combustion engine, the operation amount of the accelerator operation member, and the command value of the injection amount for the fuel injection valve. That is, when the rotational speed changes, the time appropriate for injection changes or the injection amount changes, so the target value for injecting the desired fuel within the time appropriate for injection is reached. The demand to change Further, when the operation amount of the accelerator operation member changes, the injection amount changes, so that there is a request to change the target value to inject fuel within an appropriate time for performing the injection. Further, when the command value of the injection amount for the fuel injection valve changes, there is a demand for changing the target value to inject the desired fuel within an appropriate time for performing the injection.

  And when there exists a change request | requirement, even if it is a case where a target value is changed by setting a target value using the said relational expression, the deterioration of an exhaust characteristic can be suppressed.

According to a fourth aspect of the present invention, in the third aspect of the present invention, the setting means determines the target value based on the relational expression until a predetermined time elapses after it is determined that the change request is present. It is characterized by changing.

  In the above configuration, the target value is changed based on the relational expression until a predetermined time elapses after it is determined that there is a change request, so that the change in the target value does not become abrupt and intermittent. Since it can be made continuous, the actual fuel pressure can be made to follow the target value with high accuracy by operating the fuel pump or the like.

According to a fifth aspect of the present invention, in the first or second aspect of the invention, the target is based on a rotational speed of an output shaft of the internal combustion engine and a command value of an operation amount of an accelerator operation member or an injection amount for a fuel injection valve. A map for determining a value; and a determination unit for determining whether or not a change in the target value determined by the map is equal to or greater than a predetermined threshold; and the setting unit includes a change in the target value less than the threshold. When the target value is set by the map and the change of the target value is determined to be greater than or equal to the threshold value, the target value before and after the change determined by the map is continuously connected. The target value is set using the relational expression.

  In the above configuration, by using the map, it is possible to make the target value appropriate for maintaining good exhaust characteristics in a steady state where it is not necessary to change the target value. However, in this case, when the target value determined by the map changes abruptly, the exhaust characteristics may deteriorate. In this respect, according to the above-described configuration, by setting the target value using the relational expression in such a situation, it is possible to suppress the deterioration of the exhaust characteristics even when the target value changes.

(First embodiment)
Hereinafter, a first embodiment in which a fuel injection control device according to the present invention is applied to a fuel injection control device of a common rail type diesel engine will be described with reference to the drawings.

  FIG. 1 shows the overall configuration of the engine system according to the present embodiment.

  As shown in the figure, the fuel in the fuel tank 2 is pumped up by the fuel pump 6 through the fuel filter 4. The fuel pump 6 is powered by a crankshaft 8 that is an output shaft of a diesel engine and discharges fuel. Specifically, the fuel pump 6 includes an intake metering valve 10, and the amount of fuel discharged to the outside is determined by operating the intake metering valve 10. The fuel pump 6 includes several plungers, and these plungers reciprocate between a top dead center and a bottom dead center, whereby fuel is sucked and discharged.

  The fuel from the fuel pump 6 is pressurized and supplied (pressure fed) to the common rail 12. The common rail 12 stores the fuel pumped from the fuel pump 6 in a high pressure state and supplies the fuel to the fuel injection valve 16 of each cylinder (here, four cylinders are illustrated) via the high pressure fuel passage 14. The fuel injection valve 16 is connected to the fuel tank 2 via a low pressure fuel passage 18.

  The engine system includes various sensors that detect the operating state of the diesel engine, such as a fuel pressure sensor 20 that detects the fuel pressure in the common rail 12 and a crank angle sensor 22 that detects the rotation angle of the crankshaft 8. Further, the engine system includes an accelerator sensor 24 that detects an operation amount of an accelerator pedal operated in response to a user's acceleration request.

  On the other hand, the electronic control unit (ECU 30) is composed mainly of a microcomputer, takes in the detection results of the various sensors, and controls the output of the diesel engine based on this. In particular, the ECU 30 includes a constant memory holding memory 32. The constant memory 32 is a nonvolatile memory such as an EEPROM that holds data regardless of whether power is supplied, a backup memory that holds the power supply state regardless of the state of the ignition switch, or the like. It is a storage means for holding data regardless of being off.

  The ECU 30 performs fuel injection control so as to appropriately control the output of the diesel engine. In this fuel injection control, the fuel pressure in the common rail 12 is feedback-controlled to a target value (target fuel pressure) set according to the operation state of the diesel engine.

  Here, the setting of the target fuel pressure according to the present embodiment will be described in detail.

  In the present embodiment, the target fuel pressure is set based on a relational expression that defines the change in the target fuel pressure as a function of time. Then, a transient state where a change in the target fuel pressure is required is determined based on the operation amount of the accelerator pedal and the rotational speed of the crankshaft 8, and the target fuel pressure is changed based on the relational expression at the time of the determination. Here, the change of the target fuel pressure is required mainly for the following two reasons. First, since the time required for rotation in an appropriate rotation angle region for fuel injection changes as the rotational speed of the crankshaft 8 changes, it is required to inject fuel within this time. By changing the fuel pressure. Second, the required fuel injection amount changes with the change in the amount of operation of the accelerator pedal, so that it is required to inject fuel within the time required for rotation in an appropriate rotation angle region for fuel injection. By changing the fuel pressure. In view of the fact that the output torque via the crankshaft 8 of the diesel engine depends on the rotational speed and the injection amount, the change in the target fuel pressure is caused by the change in the required torque.

  FIG. 2 shows information related to the relational expression stored in the constant storage holding memory 32. On the left side of FIG. 2 (a), a map for determining which relational expression is used based on the operation amount of the accelerator pedal and the rotational speed is shown. Here, as shown on the right side of FIG. 2A, three relational expressions (relational expressions 1 to 3) that define the change amount ΔPc of the target fuel pressure are illustrated as relational expressions. Here, relational expression 1 is a quadratic function with time t as an independent variable. Relational expression 2 is an exponential function with time as an independent variable. Furthermore, relational expression 3 is a linear function with time as an independent variable.

  FIG. 2B shows a map for determining the coefficient of the second-order term a of the time t in the relational expression 1 based on the operation amount of the accelerator pedal and the rotational speed. FIG. 2C shows a map for determining the coefficient of time t in the relational expression 2 based on the operation amount of the accelerator pedal and the rotational speed. In FIG. 2, the description of the map for the other coefficient e is omitted for convenience. However, the constant storage and holding memory 32 defines relational expressions 1 to 3 such as coefficients and intercepts of relational expressions 1 to 3. A map for setting values of all setting parameters as parameters is provided.

  By adapting the relational expressions 1 to 3 and the values of the setting parameters for these, it is possible to suppress the deterioration of exhaust characteristics in a transient state. Incidentally, each of the above adaptations is performed as follows.

  FIG. 3 shows the configuration of a system for performing the adaptation.

  As illustrated, the dynamometer 50 generates a state in which the diesel engine 40 is artificially mounted on the vehicle by absorbing the output torque of the diesel engine 40. The measuring device 52 is a device that measures the exhaust characteristics of the diesel engine 40 and the like and measures the rotational speed of the crankshaft 8 of the diesel engine 40. Further, the adaptation computer 54 operates the dynamometer 50 and appropriately sets operation amounts of various actuators of the diesel engine 40 such as the fuel pump 6 and the fuel injection valve 16, and sets each actuator via the ECU 30 according to the operation amount. Has the function of operating. Then, the adaptation computer 54 performs each of the above adaptations based on the measurement result obtained by the measurement device 52.

Specifically, this may be performed by the following procedure, for example.
(A) The relational expression is uniquely set temporarily in all regions determined by the operation amount and the rotation speed of the accelerator pedal.
(B) In each region determined by the amount of operation of the accelerator pedal and the rotational speed, the value of the setting parameter of the relational expression is provisionally determined. Here, for example, when the relational expression is the relational expression 1, the provisionally determined values for the coefficients a and b and the intercept c may be set as several sets according to the experimental design method. That is, for a specific region determined by the amount of operation of the accelerator pedal and the rotation speed, (a, b, c) = (0.5, 0.3, 0.4), (0.4 , 0.5, 0.5),...
(C) The target fuel pressure is set according to the provisionally determined value, and the exhaust characteristic is measured by the measuring device 52 while feedback control of the fuel pressure in the common rail 12 to the target fuel pressure. In addition to the feedback control of the target fuel pressure, the fuel injection valve 16 is operated to perform fuel injection according to the operation amount of the accelerator pedal and the rotational speed.
(D) Based on the measurement result of the exhaust characteristic, an appropriate value is selected from the values temporarily determined in the above (b).
(E) In the above (d), for the region where an appropriate value can be selected, the relational expression is determined to be set in the above (a).
(F) In the above (d), when there is a region where an appropriate value cannot be set, the relational expression of the region is changed and the above processing (b) to (d) is repeated again.

  The relational expression can be adapted in the above manner.

  FIG. 4 shows a procedure of processing relating to setting of the target fuel pressure using the relational expression adapted in the above aspect. This process is repeatedly executed by the ECU 30, for example, at a predetermined cycle.

  In this series of processing, according to step S10, the operation amount of the accelerator pedal detected by the accelerator sensor 24 and the rotational speed of the crankshaft 8 detected by the crank angle sensor 22 are acquired. Accordingly, it is determined whether or not the change in the target fuel pressure is a desired transient state. Here, the presence / absence of a change request for the target fuel pressure is determined as the presence / absence of a change in the injection amount determined from the operation amount of the accelerator pedal and the rotation speed, and an appropriate change in the injection time due to the change in the rotation speed.

  If it is determined that the state is a transient state, in step S14, the target fuel pressure change flag F, which is a flag for performing a process of changing the target fuel pressure, is set to "1". Further, based on the accelerator pedal operation amount and the rotational speed, the relational expression is determined using the map shown in FIG. Furthermore, the time t which is an independent variable of the relational expression is initialized.

  In subsequent step S16, the target fuel pressure is calculated. This can be done by adding the amount of change ΔPc determined by the relational expression to the target fuel pressure immediately before the processing in step S12. When calculating the change amount ΔPc, first, the setting parameter of the relational expression is determined using the map illustrated in FIG.

  The process of step S16 is continued until time t is equal to or greater than a predetermined time tt (step S18). That is, when the time tt is not yet exceeded, the series of processes shown in FIG. 4 is started next time, and even if a negative determination is made in step S12, the target fuel pressure change flag F is “1”. An affirmative determination is made in S22, and the process proceeds to step S16.

  When the time t becomes equal to or longer than the time tt (step S18: YES), the target fuel pressure change flag F is set to “0” in step S20. For this reason, after the process of step S20 is made, the target fuel pressure is fixed by the process of step S24 until it is determined in step S12 that the state is a transient state.

  FIG. 5 illustrates a target fuel pressure setting mode according to this embodiment. In FIG. 5, the solid line indicates a case where the target fuel pressure is set by a map that defines the relationship between the accelerator pedal operation amount and rotation speed and the target fuel pressure.

  As shown in the figure, at the time t1 and the time t2, the target fuel pressure is increased and changed substantially intermittently, for example, by sudden depression of the accelerator pedal. Further, at the time t3 and the time t4, the target fuel pressure is intermittently decreased and changed, for example, the accelerator pedal is suddenly released.

  On the other hand, in the figure, the broken line and the alternate long and short dash line indicate the setting mode of the target fuel pressure in the present embodiment. Here, a broken line and a dashed-dotted line have shown the case where a different relational expression is used. However, the setting of the target fuel pressure using these two relational expressions does not necessarily mean an equivalent value from the viewpoint of suppressing deterioration of exhaust characteristics. As shown in the figure, the target fuel pressure gradually increases with time from time t1 to time tt or from time t2 to time tt. In addition, after the time t3, the target fuel pressure gradually decreases even after the time t4. This is because the time from time t3 to time t4 is shorter than time tt.

  According to the embodiment described in detail above, the following effects can be obtained.

  (1) The target fuel pressure is set based on a relational expression that defines the change in the target fuel pressure as a function of time. Thereby, even if it is a case where the target fuel pressure is changed, the deterioration of the exhaust characteristic can be suppressed by adapting the relational expression so as to suppress the deterioration of the exhaust characteristic.

  (2) By using the accelerator pedal operation amount and the rotational speed, it is possible to appropriately determine the target fuel pressure change request.

  (3) The target fuel pressure is changed based on the relational expression until a predetermined time elapses after it is determined that there is a request for changing the target fuel pressure. Thereby, even when the change in the required torque is regarded as a sudden and intermittent change, the change in the target fuel pressure can be made continuous. For this reason, the actual fuel pressure in the common rail 12 can be made to follow the target fuel pressure by feedback control.

  (4) Different formulas (relational expressions 1 to 3) were used for each region divided by the rotational speed of the crankshaft 8 and the operation amount of the accelerator pedal. As a result, it is possible to use a relational expression that is more appropriately adapted to suppress the deterioration of the exhaust characteristics.

  (5) By assigning the values of the setting parameters (a to f), which are parameters for determining the relational expression, to each region divided by the rotational speed of the crankshaft 8 and the operation amount of the accelerator pedal, Relational expressions that are more appropriately adapted to suppress the deterioration can be used.

(Second Embodiment)
Hereinafter, the second embodiment will be described with reference to the drawings with a focus on differences from the first embodiment.

  In the present embodiment, basically, the target fuel pressure is set by a map that defines the relationship between the operation amount and rotation speed of the accelerator pedal and the target fuel pressure. Then, when the target fuel pressure calculated by the map changes rapidly, the target fuel pressure is set using the relational expression so as to continuously connect the target fuel pressure before and after the change.

  FIG. 6 shows a processing procedure for setting the target fuel pressure according to the present embodiment. This process is repeatedly executed by the ECU 30, for example, at a predetermined cycle.

  In this series of processing, in step S30, a map calculation is performed on the target fuel pressure PFINm based on the operation amount of the accelerator pedal and the rotational speed. Here, the map sets the target fuel pressure higher as the rotational speed is higher, and sets the target fuel pressure higher as the acceleration side operation amount of the accelerator pedal is larger. This is because the higher the rotational speed, the shorter the time required for rotation in the rotation angle region appropriate for injection, and the greater the accelerator pedal acceleration side operation amount, the greater the injection amount, and consequently the injection period. This is done in view of the expansion.

  In the subsequent step S32, it is determined whether or not the amount of change with respect to the target fuel pressure PFINm calculated in step S30 is greater than or equal to a predetermined threshold value ΔP. This threshold value ΔP has a sudden change in the target fuel pressure PFINm calculated by the map, and if the feedback control is performed so as to follow the target fuel pressure PFINm calculated by the map, there is a concern that the exhaust characteristics will deteriorate. It is for judging the situation.

  If it is determined that it is equal to or greater than the threshold value ΔP, the same processing as in steps S14 and S16 of FIG. 4 is performed in steps S34 and S36. However, the maps shown in FIG. 2 are adapted on the assumption that the target fuel pressure in the steady state is set using the above map that defines the relationship between the accelerator pedal operation amount and rotational speed and the target fuel pressure. Shall be.

  In the present embodiment, the setting of the target fuel pressure PFIN based on the relational expression is a logical sum of that the time is equal to or longer than the time tt and that the target fuel pressure PFIN set based on the relational expression matches the target fuel pressure PFINm. Repeat until the condition is met. That is, when the logical sum condition is not satisfied, when the process shown in FIG. 6 is started next time, even if a negative determination is made in step S32, it is determined that the target fuel pressure change flag F is “1” in step S42. Therefore, the process proceeds to step S36.

  When the logical sum condition is satisfied, the target fuel pressure change flag F is initialized in step S40. Thereafter, the target fuel pressure PFIN is determined in step S30 until an affirmative determination is made again in step S32. The calculated target fuel pressure PFINm is set (step S44).

  According to this embodiment described above, in addition to the effects (1), (4), and (5) of the first embodiment, the following effects can be obtained.

  (6) When the change in the target fuel pressure PFINm determined by a map that defines the relationship between the rotational speed of the crankshaft 8 and the operation amount of the accelerator pedal and the target fuel pressure is equal to or greater than a predetermined threshold ΔP, the target before and after the change determined by the map The target fuel pressure was set using the relational expression so that the fuel pressure PFINm was continuously connected. Here, by using the map, it is possible to make the target value appropriate for maintaining good exhaust characteristics in a steady state where it is not necessary to change the target fuel pressure. And when the target fuel pressure determined by the map may change suddenly and the exhaust characteristics may deteriorate, setting the target fuel pressure using the relational expression will suppress the deterioration of the exhaust characteristics even when the target fuel pressure changes can do.

(Third embodiment)
Hereinafter, the third embodiment will be described with reference to the drawings with a focus on differences from the second embodiment.

  FIG. 7 shows a processing procedure for setting the target fuel pressure according to the present embodiment. This process is repeatedly executed by the ECU 30, for example, at a predetermined cycle.

  In this series of processes, in step S50, the target fuel pressure PFINm is calculated using a map, as in step S30 of FIG. In the subsequent step S52, it is determined whether or not the amount of change in the target fuel pressure PFINm is greater than or equal to the threshold value ΔP, as in step S32 of FIG. If it is determined that the value is equal to or greater than the threshold value ΔP, the time t as an independent variable of the relational expression is initialized in step S54.

In the subsequent step S56, the target fuel pressure PFIN is calculated based on the relational expression. In this embodiment, the relational expression is as follows.
PFIN = PFINm (n−1) + {1−α (tt−t)} × {PFINm (n) −PFINm (n−1)}
However, the target fuel pressure PFINm (n) is the target fuel pressure calculated in the current process of step S50, and the target fuel pressure PFINm (n-1) is the target fuel pressure calculated in the previous process of step S50. Also according to the above equation, the target fuel pressure PFIN can be set so as to continuously connect the values before and after the change of the target fuel pressure PFINm (PFINm (n), PFINm (n-1)). Incidentally, in the above relational expression, the coefficient α is a target of adaptation.

  The target fuel pressure PFIN is set based on the above relational expression until the time reaches the time tt or more. On the other hand, when a negative determination is made in step S52, the target fuel pressure PFIN is set to the target fuel pressure PFINm calculated in step S50 (step S62).

  When an affirmative determination is made in step S58 or when the process of step S62 is completed, this series of processes is temporarily terminated.

  According to this embodiment described above, the effect (1) of the previous first embodiment and the effect (6) of the previous second embodiment can be obtained.

(Other embodiments)
Each of the above embodiments may be modified as follows.

  In the first and second embodiments, different relational expressions are used for each area divided by the accelerator pedal operation amount and the rotation speed, and the relational expressions defined in that area for each same area are used. Although the value of the setting parameter to be set is determined for each, it is not limited to this. For example, the different settings may be made for each region divided by the command value of the injection amount for the fuel injection valve 16 and the rotational speed. Furthermore, you may define the said area | region as an area | region divided | segmented by some of these operation values of an accelerator pedal, rotation speed, and the injection amount command value. In addition, for example, the relational expression may be uniquely determined and only the value of the setting parameter may be determined for each region.

  In the first embodiment, the target fuel pressure PFIN change request (output torque change request) is set according to the amount of operation of the accelerator pedal and the rotational speed. However, the present invention is not limited to this, for example, a fuel injection valve Determination may be made according to the command value of the injection amount for 16 and the rotation speed.

  In the second and third embodiments, the map that defines the relationship between the accelerator pedal operation amount and rotation speed and the target fuel pressure PFINm is used. However, the present invention is not limited to this. For example, the injection to the fuel injection valve 16 is performed. A map that defines the relationship between the command value and rotation speed of the quantity and the target fuel pressure PFINm may be used.

  The relational expression is not limited to those exemplified in the above embodiments, and may be defined using a trigonometric function, for example.

  The internal combustion engine is not limited to a diesel engine, and may be, for example, a cylinder injection gasoline engine.

The figure which shows the whole structure of the engine system in 1st Embodiment. The figure which shows the information regarding the relational expression concerning the embodiment. The figure which shows the whole structure of the system which adapts the relational expression in the embodiment. The flowchart which shows the process sequence of the setting of the target fuel pressure concerning the embodiment. The time chart which illustrates the setting mode of the target fuel pressure concerning the embodiment. The flowchart which shows the process sequence of the setting of the target fuel pressure concerning 2nd Embodiment. The flowchart which shows the process sequence of the setting of the target fuel pressure concerning 3rd Embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 6 ... Fuel pump, 8 ... Crankshaft, 12 ... Common rail, 16 ... Fuel injection valve, 20 ... Fuel pressure sensor, 30 ... ECU (one Embodiment of fuel injection control apparatus), 32 ... Memory always hold | maintain memory holding | maintenance.

Claims (5)

A pressure accumulating chamber for storing fuel in a high pressure state; a fuel pump for pumping fuel to the pressure accumulating chamber; a fuel injection valve for injecting fuel stored in the pressure accumulating chamber; and a detecting means for detecting fuel pressure in the pressure accumulating chamber. In a fuel injection control device that is applied to a fuel injection device of an internal combustion engine and that operates the fuel pump to feedback control the fuel pressure detected by the detection means to a target value,
The fuel pump is powered by the output shaft of the internal combustion engine,
Storage means for storing information relating to a relational expression that defines the change in the target value as a function of time;
Setting means for setting a target value of the feedback control based on the relational expression ,
The relational expression is provided for each region divided by at least one of an operation amount of an accelerator operation member and a command value of an injection amount for a fuel injection valve . A pressure accumulating chamber for storing fuel in a high pressure state; a fuel pump for pumping fuel to the pressure accumulating chamber; a fuel injection valve for injecting fuel stored in the pressure accumulating chamber; and a detecting means for detecting fuel pressure in the pressure accumulating chamber. In a fuel injection control device that is applied to a fuel injection device of an internal combustion engine and that operates the fuel pump to feedback control the fuel pressure detected by the detection means to a target value,
The fuel pump is powered by the output shaft of the internal combustion engine,
Storage means for storing information relating to a relational expression that defines the change in the target value as a function of time;
Setting means for setting a target value of the feedback control based on the relational expression,
A value of a setting parameter, which is a parameter for defining the relational expression, is assigned to each region divided by at least one of an operation amount of an accelerator operation member and an injection amount command value for a fuel injection valve. A fuel injection control device. A determination means for determining whether or not there is a change request for the target value based on at least one of a rotation speed of the output shaft of the internal combustion engine, an operation amount of an accelerator operation member, and a command value of an injection amount for a fuel injection valve;
3. The fuel injection control device according to claim 1, wherein the setting unit changes the target value based on the relational expression when it is determined that there is the change request . 4. 4. The fuel injection control apparatus according to claim 3, wherein the setting means changes the target value based on the relational expression until a predetermined time elapses after it is determined that there is the change request. . A map for determining the target value based on the rotational speed of the output shaft of the internal combustion engine and the command value of the operation amount of the accelerator operation member or the injection amount for the fuel injection valve;
Judgment means for judging whether or not a change in the target value determined by the map is equal to or greater than a predetermined threshold;
The setting means sets the target value by the map when the change in the target value is less than the threshold, and is determined by the map when it is determined that the change in the target value is not less than the threshold. 3. The fuel injection control apparatus according to claim 1, wherein the target value is set using the relational expression so as to continuously connect the target values before and after the change .

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