JP2008297935A - Fuel injection quantity control method for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel injection quantity control method capable of more accurately providing desired actual injection quantity even if injection characteristics with respect to the fuel temperature changes at each fuel temperature due to aging of an injector. <P>SOLUTION: A final fuel temperature correction quantity (fuel temperature correction term) Qmf is calculated by multiplying a collection fuel injection quantity Qm calculated by a corrected fuel injection quantity calculation process by a command value correction coefficient Cg calculated by a command value correction coefficient calculation process and a deterioration correction coefficient Ci calculated by a deterioration correction coefficient calculation process. Final fuel injection quantity command value Qf is calculated by adding the final fuel temperature correction quantity Qmf to a target fuel injection quantity command value Qg to the injector. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a fuel injection amount control method for controlling the injection amount of fuel supplied to an internal combustion engine such as a diesel engine, and more particularly to a method for correcting the fuel injection amount with respect to fuel temperature.

When fuel is supplied to an internal combustion engine such as a diesel engine, even if the same fuel injection amount command value is transmitted from the control device, the actual fuel injection amount (hereinafter referred to as the fuel injection amount due to the fuel temperature in the injector of the fuel supply device and the deterioration of the injector) , Described as the actual injection amount) tends to change. For example, regarding the fuel temperature in the injector, the actual injection amount tends to increase as the fuel viscosity increases as the fuel temperature decreases. In addition, regarding the deterioration of the injector over time, the actual injection amount increases when the spring of the injector springs, and carbon or the like adheres to the injector nozzle hole, or impurities in the fuel adhere to the needle inside the injector. Then, the actual injection amount tends to decrease.
Therefore, even when the actual injection amount changes due to the fuel temperature in the injector or the deterioration of the injector, the following is required to supply the desired amount of fuel required according to various operating conditions more accurately to the internal combustion engine. Techniques as shown have been proposed.

  Conventionally, a technique related to a fuel injection amount control device for correcting and calculating a fuel injection amount of a diesel engine has been proposed and disclosed (for example, see Patent Document 1). This fuel injection amount control device for a diesel engine is based on the difference between the fuel temperature and the actual engine speed and the target engine speed when the engine is in an idling stable state. ) And the presence or absence of deterioration with time, and learning. At the time of starting the engine, the fuel injection control device corrects the starting injection amount based on the learning value and the fuel temperature.

  Also, subtract the estimated value of the fuel injection amount after aging deterioration of the injector from the estimated value of the fuel injection amount when the injector is new, and replace the increase amount with the aging deterioration amount of the fuel injection amount. A technique relating to a fuel injection device for an internal combustion engine that corrects the command injection amount in consideration of the above has been proposed and disclosed (see, for example, Patent Document 2). In this internal combustion engine fuel injection device, first, a command injection amount is obtained by adding the injection correction amount calculated from the fuel temperature of the fuel supply pump to the basic injection amount, and the diesel engine is operated using the command injection amount. . For example, when a predetermined travel distance is reached and the engine operating condition satisfies the measurement condition, the fuel injection amount (fuel consumption) is measured, and compared with the fuel injection amount at the previous measurement, Seeking.

Japanese Patent Laid-Open No. 11-229925 JP 2005-307911 A

On the other hand, the present inventors have found that the fuel injection characteristics with respect to the fuel temperature fluctuate due to deterioration with time.
However, in the techniques for controlling the injection amount of the fuel supplied to the internal combustion engine described in Patent Document 1 and Patent Document 2, both the fuel based on the correction of the fuel injection amount based on the fuel temperature and the deterioration of the injector The injection amount is corrected separately. As described above, when the correction of the fuel injection amount based on the fuel temperature and the correction of the fuel injection amount based on the deterioration of the injector are separately performed, when the injection characteristics with respect to the fuel temperature change depending on each fuel temperature due to the deterioration of the injector over time, The fuel injection amount cannot be corrected properly.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to obtain a desired actual injection amount more accurately even when the injection characteristic with respect to the fuel temperature changes depending on each fuel temperature due to the deterioration of the injector with time. It is an object to provide a fuel injection amount control method capable of performing the above.

Means and effects for solving the problems

  The fuel injection amount control method according to the present invention relates to a fuel injection amount control method for controlling the injection amount of fuel supplied to an internal combustion engine such as a diesel engine. The fuel injection amount control method according to the present invention has the following features in order to achieve the above object. That is, the fuel injection amount control method of the present invention includes the following features alone or in combination as appropriate.

  The first feature of the fuel injection amount control method according to the present invention for achieving the above object is to calculate a fuel temperature correction term reflecting the influence of the fuel temperature and reflect it in the fuel injection amount injected from the injector. In a fuel injection amount control method for an engine, a step of calculating a target fuel injection amount command value from an accelerator opening and an engine speed, a fuel temperature detection step of detecting a fuel temperature in the injector, and deterioration of the injector over time A deterioration correction coefficient calculating step for calculating a deterioration correction coefficient for the influence of the fuel, and a fuel temperature correction term for calculating the fuel temperature correction term based on the target fuel injection amount command value, the fuel temperature, and the deterioration correction coefficient. A calculation step.

  According to this configuration, by calculating the fuel temperature correction term based on each value of the target fuel injection amount command value, the fuel temperature, and the deterioration correction coefficient, the calculated fuel temperature correction term can be calculated with respect to the fuel temperature in the injector. It is a correction term that reflects deterioration over time in the characteristics. That is, according to this method, the influence of the deterioration of the injector over time can be reflected on the fuel temperature characteristic of the injector. Therefore, even if the injection characteristic with respect to the fuel temperature changes depending on each fuel temperature due to the deterioration of the injector over time, it is possible to obtain a desired actual injection amount more accurately.

  A second feature of the fuel injection amount control method according to the present invention is that the deterioration correction coefficient becomes a value that increases the absolute value of the fuel temperature correction term as the deterioration with time progresses.

  According to this configuration, the deterioration correction coefficient is a deterioration correction coefficient reflecting the influence of deterioration with time based on the fuel temperature, and by using this coefficient, the injection characteristics with respect to the fuel temperature change depending on each fuel temperature due to deterioration with time of the injector. Even if it does, it becomes possible to obtain a desired actual injection amount more accurately.

  The third feature of the fuel injection amount control method according to the present invention is that a corrected fuel injection amount for the fuel temperature is calculated from the fuel temperature, and the corrected fuel injection amount is calculated in the fuel temperature correction term calculation step. The fuel temperature correction term is calculated by reflecting the deterioration correction coefficient. According to this configuration, the calculated fuel temperature correction term is a correction term in which deterioration with time is reflected in the injection characteristics with respect to the fuel temperature in the injector.

  A fourth feature of the fuel injection amount control method according to the present invention is that, in the fuel temperature correction term calculation step, the fuel temperature correction term is calculated by multiplying the correction fuel injection amount by the deterioration correction coefficient. That is. According to this configuration, the calculated fuel temperature correction term is a correction term in which deterioration with time is reflected in the injection characteristics with respect to the fuel temperature in the injector.

  A fifth feature of the fuel injection amount control method according to the present invention is that a command value correction coefficient for the target fuel injection amount command value is calculated, and in the fuel temperature correction term calculation step, The fuel temperature correction term is calculated by multiplying the command value correction coefficient and the deterioration correction coefficient.

  According to this configuration, by calculating the fuel temperature correction term by further multiplying the corrected fuel injection amount based on the fuel temperature by the command value correction coefficient for the target fuel injection amount command value to the injector, a desired actual injection amount is obtained. Can be obtained more accurately.

  Further, a sixth feature of the fuel injection amount control method according to the present invention is that the calculation step of the corrected fuel injection amount is based on a map showing a relationship among the fuel temperature, the corrected fuel injection amount, and a common rail pressure. , Calculating the corrected fuel injection amount with respect to the fuel temperature, the calculating step of the command value correction coefficient is a relationship between the target fuel injection amount command value, the command value correction coefficient, and the common rail pressure. This is a step of calculating the command value correction coefficient for the target fuel injection amount command value based on the map shown.

  According to this configuration, the target fuel injection amount command value and the map for calculating the corrected fuel injection amount and the map for calculating the command value correction coefficient are learned based on the operation result data. The error from the actual injection amount can be reduced.

  Further, a seventh feature of the fuel injection amount control method according to the present invention is that the deterioration correction coefficient calculating step calculates the deterioration correction coefficient based on a map showing a relationship between a vehicle travel distance and the deterioration correction coefficient. It is a process. According to this configuration, the vehicle travel distance, which is one of the indicators of the deterioration of the injector over time, can be reflected in the deterioration correction coefficient, and the deterioration over time of the injector can be appropriately reflected in the fuel temperature correction term.

  An eighth feature of the fuel injection amount control method according to the present invention is that the deterioration correction coefficient calculating step shows a relationship between the fuel temperature in the injector and the first correction coefficient when the internal combustion engine is operated. The first correction coefficient is calculated based on a map, the second correction coefficient is calculated based on a map showing the relationship between the accumulated time during which the internal combustion engine is operated and the second correction coefficient, and the first correction coefficient and the first correction coefficient are calculated. The deterioration correction coefficient is calculated by multiplying by two correction coefficients.

  According to this configuration, the fuel temperature in the injector when operating the internal combustion engine, which is one of the indicators of the deterioration of the injector over time, and the accumulated operation time at that time can be reflected in the deterioration correction coefficient, and the fuel temperature correction term can be reflected in the injector temperature correction term. The deterioration with time can be appropriately reflected.

  Further, a ninth feature of the fuel injection amount control method according to the present invention is that the command value correction coefficient calculating step includes a target pilot injection amount command value, a target main injection amount command value, and a target after injection amount command value. It is a step of calculating a plurality of command value correction coefficients for a plurality of target fuel injection amount command values consisting of at least the target main injection amount command value.

  According to this configuration, the corrected fuel injection amount corresponding to the fuel temperature can be appropriately distributed to the target main injection amount command value and at least one command value of the target pilot injection amount command value and the target after injection amount command value. It is possible to obtain an optimum main injection amount command value and an optimum injection amount command value composed of at least one of the pilot injection amount command value and the after injection amount command value.

  Further, a tenth feature of the fuel injection amount control method according to the present invention is that, in the fuel temperature detection step, the fuel temperature in the injector is connected to a fuel return pipe communicating with a fuel supply pump and a fuel tank. It is considered that it is equal to the fuel temperature of the pump part at the connection part of the fuel supply pump. According to this configuration, the fuel temperature in the injector can be easily determined.

  The eleventh feature of the fuel injection amount control method according to the present invention is that it does not depend on the fuel temperature in the injector, and the spring of the injector, the injection hole of the injector, and the needle of the injector. A correction term based on general deterioration with time of the injector depending on at least one of the impurity adhesions is reflected in the fuel injection amount injected from the injector. According to this configuration, it is possible to separately reflect the injection characteristic based on the general deterioration of the injector with time in the fuel injection amount.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. The fuel injection amount control method according to the present invention is a fuel injection amount control method applicable to both a gasoline engine and a diesel engine. In the following description, an example in which the fuel injection amount control method according to the present invention is applied to a vehicle equipped with a diesel engine will be described.

First, based on FIG. 1, the change of the injection characteristic with respect to the fuel temperature of an injector is demonstrated. FIG. 1 shows a fuel temperature Ti (° C.) and an actual injection amount Qr (mm ³ / mm) in the injector when the injector performs fuel injection based on a fixed fuel injection amount command value on the assumption of a common rail fuel injection device. It is a figure which shows the relationship with st). A dotted line 100 in FIG. 1 is a curve showing a change in the actual injection amount Qr before the deterioration of the injector, and a solid line 101 in FIG. 1 is a curve showing a change in the actual injection amount Qr after the deterioration of the injector. The injector having the injection characteristic indicated by the solid line 101 in FIG. 1 is premised on that there is almost no change in the injection characteristic with respect to general deterioration with time. Here, an alternate long and short dash line 102 in FIG. 1 is a curve showing a change in the actual injection amount Qr when the actual injection amount after deterioration increases due to general deterioration of the injector with time. General deterioration over time refers to a factor that changes the injection characteristics regardless of the fuel temperature. As described above, the adhesion of impurities, etc. to the spring sag, the injector nozzle hole, or the needle in the injector, Etc. These factors include those that increase or decrease the actual injection amount. As a result, whether the actual injection amount changes after deterioration depends on the model, and it is tested for each model. It is necessary to confirm by. In any case, when a change in the injection characteristic with respect to general deterioration with time occurs, the injection characteristic becomes such that the solid line 101 is slid up and down, as indicated by the one-dot chain line 102 shown in FIG.

  As indicated by a dotted line 100 in FIG. 1, the actual injection amount Qr before the injector deterioration shows a tendency to increase as the fuel temperature Ti in the injector decreases. On the other hand, as indicated by a solid line 101 in FIG. 1, the actual injection amount Qr after the deterioration of the injector greatly increases as the fuel temperature Ti decreases, compared to the actual injection amount Qr before the deterioration of the injector, and the fuel temperature Ti As the value increases, the difference from the actual injection amount Qr before the injector deterioration tends to decrease. As described above, the inventors of the present invention do not change the actual injection amount Qr with respect to the fuel temperature of the injector uniformly from the actual injection amount Qr before the injector deterioration with respect to each fuel temperature Ti but according to the fuel temperature Ti. The knowledge that it fluctuates was obtained.

  Next, FIG. 2 is a diagram showing a device configuration for using the fuel injection amount control method according to one embodiment of the present invention. An arrow indicated by a solid line in FIG. 2 indicates the flow of fuel, and an arrow indicated by an alternate long and short dash line in FIG. 2 indicates the direction of the control signal. As shown in FIG. 2, a vehicle equipped with a diesel engine for using the fuel injection amount control method according to this embodiment includes a fuel tank 5 that stores fuel, and sucks fuel from the fuel tank 5 and supplies it to the injector 2. A fuel supply pump 1, a common rail 3 for storing a certain amount of high-pressure fuel between the fuel supply pump 1 and the injector 2, and a combustion chamber (not shown) for supplying fuel supplied from the common rail 3 to the engine (not shown). ) And an engine control controller 4 for controlling the fuel supply pump 1, the injector 2, and the like.

  The fuel supply pipe 31 is a pipe that communicates the fuel supply pump 1 and the common rail 3, the fuel return pipe 32 is a pipe that communicates the fuel supply pump 1 and the fuel tank 5, and the fuel return pipe 33 is an injector. 2 and a fuel tank 5 communicate with each other. The fuel return pipe 32 and the fuel return pipe 33 are joined before being connected to the fuel tank 5.

  The fuel stored in the fuel tank 5 is sucked up by the fuel supply pump 1, supplied to the injector 2 through the fuel supply pipe 31 and through the common rail 3, and injected from the injector 2 into the combustion chamber of the engine. On the other hand, a part of the fuel is returned to the fuel tank 5 from the fuel supply pump 1 and the injector 2 through the fuel return pipes (32, 33), and the pressure of the fuel is adjusted.

  The fuel supply pump 1 is an assembly of a low-pressure feed pump that sucks up fuel from a fuel tank 5 and a supply pump that discharges the sucked-up fuel at high pressure. A fuel temperature sensor 21 is connected to a fuel return pipe 32. And the fuel temperature sensor 21 measures the fuel temperature Tp of the pump section. Further, the common rail 3 includes a fuel pressure sensor 22, and the fuel pressure sensor 22 measures the common rail pressure Pcr. Signals of the pump unit fuel temperature Tp and the common rail pressure Pcr are sent to the engine control controller 4. In addition, signals from the engine speed sensor 23, the accelerator opening sensor 24, and the like are also sent to the engine control controller 4. The engine control controller 4 receives signals from various sensors (21, 22, 23, 24, etc.), the fuel supply pump 1, etc., performs various calculations, and sends commands to the fuel supply pump 1, the injector 2, etc. The fuel injection amount injected from the injector 2 is controlled.

Next, an embodiment of the fuel injection amount control method according to the present invention will be described in detail. FIG. 3 is a diagram showing a calculation flow of the final fuel injection amount command value Qf transmitted from the engine controller 4 to the injector 2 in the engine controller 4. In the following description, as an example, the pump part fuel temperature Tp = 95 ° C., the common rail pressure Pcr = 80 MPa, the target pilot injection amount command value Qgpl = 2 mm ³ / st, the target main injection amount command value Qgm = 20 mm ³ / The condition of st was used.

As shown in FIG. 3, first, the engine controller 4 calculates a target fuel injection amount command value Qg based on the output values of the engine speed sensor 23 and the accelerator opening sensor 24 (step 1, hereinafter referred to as S1 and S1). The other steps are the same).
Next, a fuel temperature detection step S2 for detecting the fuel temperature Ti in the injector 2 is performed. In this fuel temperature detection step, the fuel temperature Ti in the injector 2 is considered to be equal to the pump portion fuel temperature Tp measured by the fuel temperature sensor 21 of the fuel supply pump 1 connected to the fuel return pipe 32. That is, the fuel temperature Ti = 95 ° C. By assuming that the fuel temperature Ti and the pump portion fuel temperature Tp are equal, the fuel temperature Ti can be easily determined. The fuel temperature Ti in the injector 2 is measured by, for example, providing a fuel temperature sensor in the A portion of the fuel return pipe 33 on the side close to the injector 2 to measure the injector return fuel temperature in the A portion. The return fuel temperature may be regarded as being equal and determined. Depending on the actual equipment configuration from the fuel supply pump 1 to the injector 2, the temperature difference between the fuel temperature in the pump section and the fuel temperature in the injector 2 may be a large value of 10 degrees or more. In such a case, prediction is made from the engine speed Ne measured by the engine speed sensor 23, the pump portion fuel temperature Tp, the common rail pressure Pcr, the fuel injection amount setting value (past final fuel injection amount command value Qf), and the like. It is good to calculate and to calculate fuel temperature Ti.

  Next, a corrected fuel injection amount calculating step (S3) for calculating a corrected fuel injection amount Qm for the fuel temperature Ti from the fuel temperature Ti calculated in S2. In the present corrected fuel injection amount calculation step, the corrected fuel injection amount Qm for the fuel temperature Ti is calculated based on a map showing the relationship between the fuel temperature Ti, the corrected fuel injection amount Qm, and the common rail pressure Pcr. Here, FIG. 4 is a map showing the relationship between the fuel temperature Ti in the injector 2 and the corrected fuel injection amount Qm when the common rail pressure is 80 MPa. In the present embodiment, since the common rail pressure Pcr is 80 MPa, the relationship between the fuel temperature Ti and the corrected fuel injection amount Qm when the common rail pressure Pcr is 80 MPa is shown in FIG.

As shown in FIG. 4, the corrected fuel injection amount Qm is a correction amount of “−” when the fuel temperature Ti is lower than about 90 ° C., and a correction amount of “+” when the fuel temperature Ti is higher than about 90 ° C. It has become. That is, according to this map, the actual injection amount Qr increases or decreases with respect to the desired actual injection amount at about 90 ° C. Note that the map value is determined by the conditions of use of the vehicle, and is not limited to the map value shown in FIG. 4 (the same applies to other maps shown below). Further, if the common rail pressure Pcr is different, the map value at the different common rail pressure Pcr is naturally used. From the map shown in FIG. 4, the corrected fuel injection amount Qm for the fuel temperature Ti = 95 ° C. when the common rail pressure Pcr is 80 MPa is 0.2 mm ³ / st.

  Returning to FIG. 3, next, a command value correction coefficient calculation step (S4) for calculating a command value correction coefficient Cg for the target fuel injection amount command value Qg to the injector 2 is performed. In the command value correction coefficient calculation step, the command value correction coefficient for the target fuel injection quantity command value Qg is based on a map showing the relationship between the target fuel injection quantity command value Qg, the command value correction coefficient Cg, and the common rail pressure Pcr. Cg is calculated.

As described above, in the present embodiment, the target pilot injection amount command value Qgpl, which is the target value of the pilot injection amount, is 2 mm ³ / st as the target fuel injection amount command value Qg, which is the target value of the main injection amount. The target main injection amount command value Qgm is set to 20 mm ³ / st (two target fuel injection amount command values Qg, ie, a target pilot injection amount command value Qgpl and a target main injection amount command value Qgm are used). FIG. 5 is a map showing the relationship between the common rail pressure Pcr and the command value correction coefficient Cg (Cgpl, Cgm) at a predetermined target fuel injection amount command value Qg (Qgpl, Qgm). FIG. 5A is a map showing the relationship between the common rail pressure Pcr and the command value correction coefficient Cgpl when the target fuel injection amount command value Qgpl is 2 mm ³ / st, and FIG. It is a map which shows the relationship between the common rail pressure Pcr and the command value correction coefficient Cgm when the injection amount command value Qgm is 20 mm ³ / st.

From the map shown in FIG. 5A, the command value correction coefficient Cgpl for the target pilot injection amount command value Qgpl = 2 mm ³ / st when the common rail pressure Pcr is 80 MPa is about 0.68, and the target main injection amount command value The command value correction coefficient Cgm for Qgm = 20 mm ³ / st is about 1.99. Note that if the values of Qgpl and Qgm are different, the map values at the different Qgpl and Qgm are naturally used. Further, as the target fuel injection amount command value Qg, at least the target main injection amount command value Qgm is used, and in addition, the target pilot injection amount command value Qgpl and the target after injection amount command value Qgaf (target value of the after injection amount) are targeted. It can be used as the fuel injection amount command value Qg. Thus, the corrected fuel injection amount Qm for the fuel temperature Ti is appropriately distributed to the target main injection amount command value Qgm and at least one of the target pilot injection amount command value Qgpl and the target after injection amount command value Qgaf. can do.

  Returning to FIG. 3, next, a deterioration correction coefficient calculation step (S5) for calculating the deterioration correction coefficient Ci of the injector 2 with respect to the deterioration (deterioration with time) of the injector 2 is performed. In this deterioration correction coefficient calculation step, a first correction coefficient Cia is calculated based on a map showing a relationship between the fuel temperature Ti in the injector 2 when the diesel engine is operated and the first correction coefficient Cia, and the diesel engine is The second correction coefficient Cib is calculated based on the map indicating the relationship between the accumulated accumulated time H and the second correction coefficient Cib, and the calculated first correction coefficient Cia and the calculated second correction coefficient Cib are multiplied. A deterioration correction coefficient Ci is calculated.

  FIG. 6 is a map (FIG. 6 (a)) showing the relationship between the fuel temperature Ti in the injector 2 and the first correction coefficient Cia when the diesel engine is operated, and the accumulated operation time H and the first 2 is a map (FIG. 6B) showing a relationship with two correction coefficients Cib. Here, for example, it is assumed that the diesel engine has been operated in the past for 250 hours at a fuel temperature Ti = 110 ° C. and 100 hours at a fuel temperature Ti = 120 ° C. From the map shown in FIG. 6A, the first correction coefficient Cia when the fuel temperature Ti is 110 ° C. is 0.2, and the first correction coefficient Cia when the fuel temperature Ti is 120 ° C. is 0.5. It becomes. Further, from the map shown in FIG. 6B, the second correction coefficient Cib when the operation integration time H is 250 h is 0.45, and the second correction coefficient Cib when the operation integration time H is 100 h is 0. .2 Thus, the deterioration correction coefficient Ci of the injector 2 is 0.2 = 0.45 (fuel temperature Ti = 250 ° C. at 110 ° C.) + 0.5 × 0.2 (fuel temperature Ti = 100 ° C. at 120 ° C.) = 0.19 Become. As a result, the fuel temperature Ti when the internal combustion engine is operated, which is one of the indicators of deterioration with time of the injector 2, and the operation accumulated time H at that time can be reflected in the corrected fuel injection amount Qm. The deterioration with time of the injector 2 can be appropriately reflected inside.

  Returning to FIG. 3, the final fuel is calculated by multiplying the corrected fuel injection amount Qm calculated in S3 by the command value correction coefficient (Cgpl, Cgm) calculated in S4 and the deterioration correction coefficient Ci calculated in S5. A temperature correction amount (fuel temperature correction term) (Qmfpl, Qmfm) is calculated (fuel temperature correction term calculation step, S6), and the final fuel temperature correction is made to the target fuel injection amount command value (Qgpl, Qgm) to the injector 2 The final fuel injection amount command value (Qfpl, Qfm) is calculated by adding the amounts (Qmfpl, Qmfm) (S7). A final fuel injection amount calculation step is performed. Here, Qmfp1 and Qmfm are final corrected fuel injection amounts for pilot injection and main injection, respectively. Qfp1 and Qfm are final fuel injection amount command values for pilot injection and main injection, respectively.

^{Specifically, Qmfpl = 0.2mm 3 /st×0.68×0.19=0.026mm 3 /st,Qmfm=0.2mm} 3 /st×1.99×0.19=0.076mm 3 / St (S6). Then, the final fuel injection amount command value (Qfpl, Qfm) ^becomes Qfpl = 2 + 0.026 = 2.026mm 3 /st,Qfm=20+0.076=20.076mm 3 / st (S7). As a result, the final fuel injection amount command value Qfpl for the target pilot injection amount command value Qgpl = ^2mm 3 / st, the final fuel injection amount 2.026mm ³ / st, and the relative target main injection amount command value Qgm = 20mm ³ / st The command value Qfm is 20.076 mm ³ / st.

  When the final fuel injection amount command value (Qfpl, Qfm) is calculated, the engine control controller 4 transmits a signal of the final fuel injection amount command value (Qfpl, Qfm) to the injector 2, and based on this signal, The injector 2 injects fuel into the combustion chamber of the engine.

  By correcting the corrected fuel injection amount Qm based on the fuel temperature Ti by the deterioration correction coefficient Ci of the injector 2 to calculate the final fuel temperature correction amount (fuel temperature correction term) Qmf (S6), the correction based on the fuel temperature The deterioration over time of the injector 2 can be reflected in the term. Therefore, the final fuel temperature correction amount Qmf to be added to the target fuel injection amount command value Qg is based on the injection characteristics with respect to the fuel temperature reflecting the deterioration with time. Thereby, even if the injection characteristics with respect to the fuel temperature Ti change due to the deterioration of the injector 2 with time, the desired actual injection amount Qr (target fuel injection amount command value Qg) can be obtained more accurately. . Further, the map shown in FIG. 4 for calculating the corrected fuel injection amount Qm, the map shown in FIG. 5 for calculating the command value correction coefficient Cg, and the map shown in FIG. 6 for calculating the deterioration correction coefficient Ci are shown. The error between the target fuel injection amount command value Qg and the actual injection amount Qr can be further reduced by learning the map based on the operation result data. As a result, the engine reliability, drivability, and exhaust performance are hardly affected by the deterioration of the injector 2 over time.

  In the deterioration correction coefficient calculation step (S5) for calculating the deterioration correction coefficient Ci of the injector 2, the deterioration correction coefficient Ci is calculated based on a map showing the relationship between the vehicle travel distance L and the deterioration correction coefficient Ci. Good. FIG. 7 is a map showing the relationship between the vehicle travel distance L and the deterioration correction coefficient Ci. From FIG. 7, for example, the deterioration correction coefficient Ci when the vehicle travel distance L = 50,000 km is about 0.14. As a result, the vehicle travel distance L, which is one of the indicators of deterioration over time of the injector 2, can be reflected in the corrected fuel injection amount Qm, and the deterioration over time of the injector 2 can be appropriately reflected in the correction term for the fuel temperature Ti. it can.

Further, in the above-described embodiment, it is assumed that the injector has the injection characteristic indicated by the solid line 101 in FIG. 1, and the general deterioration over time that changes the injection characteristic regardless of the fuel temperature is not reflected in the correction. The deterioration correction coefficient Ci is a coefficient that increases the value (absolute value) of the final fuel temperature correction amount Qmf as the deterioration of the injector 2 with time progresses (as the injection characteristic shifts from the dotted line 100 to the solid line 101 in FIG. 1). Become. Note that general aging deterioration of the injector may be reflected in the correction. An example in which the actual injection amount after deterioration increases due to general deterioration over time, such as the spring sag, the injection hole of the injector, that is, the adhesion of impurities or the like to the needle, and the like is shown in FIG. Is shown. When the injection characteristics of the injector after aging change to either increase or decrease of the actual injection amount regardless of the fuel temperature, with the final fuel temperature correction amount Qmf with respect to the target fuel injection amount command value Qg, A correction term reflecting general deterioration with time may be added to calculate the final fuel injection amount command value Qf. The present invention reflects the influence of deterioration over time in the correction to the fuel temperature, and adding a correction term based on other different points in calculating the final fuel injection amount command value does not disturb the present invention. .
In the above-described embodiment, the calculation formula for adding the final fuel temperature correction amount Qmf as the fuel temperature correction term is shown. However, if each value is changed, the fuel temperature correction term is used as the final fuel temperature correction coefficient, and the target fuel is calculated. A formula for calculating the final fuel injection amount command value Qf by multiplying the injection amount command value Qg may be used.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made as long as they are described in the claims. .

It is a figure which shows the relationship between the fuel temperature in an injector, and an actual injection quantity. It is a figure which shows the apparatus structure for using the fuel injection amount control method which concerns on one Embodiment of this invention. It is a figure which shows the calculation flow of the last fuel injection amount command value. It is a map which shows the relationship between the fuel temperature in an injector, and correction | amendment fuel injection amount when a common rail pressure is 80 Mpa. It is a map which shows the relationship between a common rail pressure and a command value correction coefficient in a predetermined target fuel injection amount command value. 4 is a map showing the relationship between the fuel temperature in the injector and the first correction coefficient, and a map showing the relationship between the vehicle operation integrated time and the second correction coefficient. It is a map which shows the relationship between a travel distance and a degradation correction coefficient.

Explanation of symbols

1: Fuel supply pump 2: Injector 3: Common rail 4: Engine control controller 5: Fuel tank Ti: Fuel temperature in the injector Qm: Corrected fuel injection amount Ci: Degradation correction coefficient Qmf: Final fuel temperature correction amount Qg: Target fuel injection Amount command value Qf: Final fuel injection amount command value

Claims (11)

In the fuel injection amount control method for an internal combustion engine, a fuel temperature correction term that reflects the influence of the fuel temperature is calculated and reflected in the fuel injection amount injected from the injector.
A step of calculating a target fuel injection amount command value from the accelerator opening and the engine speed;
A fuel temperature detecting step for detecting a fuel temperature in the injector;
A deterioration correction coefficient calculation step for calculating a deterioration correction coefficient for the influence of deterioration over time of the injector,
A fuel temperature correction term calculation step for calculating the fuel temperature correction term based on the target fuel injection amount command value, the fuel temperature, and the deterioration correction coefficient;
A fuel injection amount control method for an internal combustion engine, comprising:   2. The fuel injection amount control method for an internal combustion engine according to claim 1, wherein the deterioration correction coefficient becomes a value that increases the absolute value of the fuel temperature correction term as the deterioration with time progresses. Calculate the corrected fuel injection amount for the fuel temperature from the fuel temperature,
The internal combustion engine according to claim 1 or 2, wherein, in the fuel temperature correction term calculation step, the fuel temperature correction term is calculated by reflecting the deterioration correction coefficient with respect to the correction fuel injection amount. Fuel injection amount control method.   4. The fuel injection amount control for an internal combustion engine according to claim 3, wherein, in the fuel temperature correction term calculation step, the fuel temperature correction term is calculated by multiplying the correction fuel injection amount by the deterioration correction coefficient. Method. Calculating a command value correction coefficient for the target fuel injection amount command value;
4. The fuel temperature correction term is calculated by multiplying the corrected fuel injection amount by the command value correction coefficient and the deterioration correction coefficient in the fuel temperature correction term calculation step. Item 5. A fuel injection amount control method for an internal combustion engine according to Item 4. The step of calculating the corrected fuel injection amount is a step of calculating the corrected fuel injection amount with respect to the fuel temperature based on a map showing a relationship between the fuel temperature, the corrected fuel injection amount, and a common rail pressure,
The step of calculating the command value correction coefficient includes the step of correcting the command value with respect to the target fuel injection amount command value based on a map showing a relationship between the target fuel injection amount command value, the command value correction coefficient, and the common rail pressure. 6. The fuel injection amount control method for an internal combustion engine according to claim 5, wherein the method is a step of calculating a coefficient.   7. The deterioration correction coefficient calculating step is a step of calculating the deterioration correction coefficient based on a map showing a relationship between a vehicle travel distance and the deterioration correction coefficient. A fuel injection amount control method for an internal combustion engine.   The deterioration correction coefficient calculating step calculates the first correction coefficient based on a map showing a relationship between the fuel temperature in the injector and the first correction coefficient when the internal combustion engine is operated, and operates the internal combustion engine. Calculating the deterioration correction coefficient by calculating the second correction coefficient based on a map indicating the relationship between the integration time and the second correction coefficient, and multiplying the first correction coefficient and the second correction coefficient; The fuel injection amount control method for an internal combustion engine according to any one of claims 5 to 7, wherein:   The step of calculating the command value correction coefficient includes a plurality of target fuel injections including at least the target main injection amount command value among a target pilot injection amount command value, a target main injection amount command value, and a target after injection amount command value. 9. The fuel injection amount control method for an internal combustion engine according to any one of claims 5 to 8, which is a step of calculating a plurality of the command value correction coefficients for a command value.   In the fuel temperature detection step, the fuel temperature in the injector is assumed to be equal to the fuel temperature of the pump section at the connection portion of the fuel supply pump connected to a fuel return pipe that connects the fuel supply pump and the fuel tank. 10. The fuel injection amount control method for an internal combustion engine according to claim 1, wherein the fuel injection amount is controlled.   The general aging of the injector which does not depend on the fuel temperature in the injector but depends on at least one of the spring of the injector, the injection hole of the injector, and the adhesion of impurities to the needle of the injector. The fuel injection amount control method for an internal combustion engine according to any one of claims 1 to 10, wherein a correction term based on deterioration is reflected in a fuel injection amount injected from the injector.

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