JP4692239B2 - Fuel injection control device - Google Patents

Description

  The present invention is mounted on a vehicle including a connection device capable of transmitting rotation of the output shaft to the driven shaft while sliding the driven shaft connected to the drive wheel with respect to the output shaft of the on-vehicle internal combustion engine. The present invention relates to a fuel injection control device that learns a deviation amount of an injection characteristic of a fuel injection valve of an internal combustion engine.

  As this type of fuel injection control device, for example, as seen in Patent Document 1 below, in a manual transmission vehicle equipped with a diesel engine, when the clutch is in a disconnected state and the vehicle is in a non-injection deceleration state, It has also been proposed that the deviation amount of the injection characteristic is learned assuming that the learning condition is satisfied. Specifically, when the learning condition is satisfied, the amount of rotation increase of the output shaft is detected by performing single injection. Here, when the clutch is disengaged, the output shaft of the diesel engine and the driven shaft connected to the drive wheels are disconnected. Therefore, when the learning condition is satisfied, the rotational increase amount is the amount of fuel actually injected. And has a strong correlation. Therefore, the amount of fuel actually injected can be detected based on the amount of increase in rotation, and consequently, the amount of deviation in the injection characteristics of the fuel injection valve can be learned with high accuracy.

However, since the learning is performed only when the output shaft of the diesel engine is disconnected from the driving wheel, the control device has a demerit that the number of times of learning is small. In particular, when the control device is applied to an automatic transmission vehicle, the disengaged state of the clutch corresponds to when the shift lever is set to neutral, so that the learning opportunities are extremely reduced. On the other hand, when learning the deviation amount of the injection characteristic in a state other than neutral, the output generated by the injection of the same injection amount according to the connection state of the engine output shaft and the driven shaft by the torque converter. Since the rotational state of the shaft fluctuates, the learning accuracy decreases.
Japanese Patent Laying-Open No. 2005-036788

  The present invention has been made to solve the above problems, and an object of the present invention is to provide a fuel injection control device capable of learning the deviation amount of the injection characteristic with high accuracy while increasing the learning frequency. There is.

  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 internal combustion engine is a diesel engine, a calculation means for calculating a slip ratio indicating a rotational deviation between the output shaft and the driven shaft, and a fuel injection valve of the internal combustion engine. A deviation amount of the injection characteristic of the fuel injection valve is determined on the basis of an injection unit that performs fuel injection by operating according to a command value of a predetermined injection amount, and a rotation increase amount of the output shaft detected in association with the fuel injection. and a learning means for learning, said learning means, a pilot injection, a time of pre-injection and an after either a is the internal combustion engine output torque is the main for producing an injection infinitesimal amount of injection than the injection In order to learn the deviation amount of the injection characteristic and to generate a predetermined rotation increase amount for use in learning the deviation amount, the injection amount to be learned of the deviation amount is set to the slip ratio. Increase according to Means for setting the corrected value as the command value; and means for converting a difference between the detected rotation increase amount and the predetermined rotation increase amount into a deviation amount of the injection characteristic based on the slip ratio. It is characterized by providing.

In the above configuration, even if fuel injection is performed with the injection amount ( desired injection amount ) that is the learning target of the deviation amount, the rotation change amount (rotation increase amount) of the output shaft is not uniquely determined, and the connecting device It fluctuates according to the connection state of. Therefore, in the above configuration, in order to generate a predetermined rotation change amount ( desired rotation change amount ) to be used for learning the deviation amount, the desired injection amount is increased and corrected in accordance with the actual slip rate. For this reason, when the amount of change in rotation detected with fuel injection deviates from the desired amount of change in rotation, the difference can be considered to be caused by the amount of deviation in the injection characteristics of the fuel injection valve. For this reason, the difference between the detected rotation change amount and the desired rotation change amount can be converted into the deviation amount of the injection characteristic with high accuracy.

  According to a second aspect of the present invention, in the first aspect of the present invention, the injection unit performs the fuel injection when a slip is allowed between the output shaft and the driven shaft.

  When the output shaft and the driven shaft are connected so as not to slip, the output shaft, the driven shaft, and the drive wheel constitute one huge rotating body. Since this rotating body rotates while applying a complicated force such as a torsional force, complicated fluctuations are also applied to the rotation state of the output shaft. In this regard, in the above configuration, in order to learn the amount of deviation when slippage is allowed between the output shaft and the driven shaft, a complicated variation on the driven shaft side can be treated as a disturbance to the output shaft. Moreover, since slippage is allowed between the output shaft and the driven shaft, rotational fluctuations on the driven shaft side are transmitted to the output shaft in a smoothed manner, and rotational fluctuations on the driven shaft side, etc. It is possible to favorably suppress a decrease in learning accuracy due to.

The invention according to claim 3 is the invention according to claim 1 or 2, wherein the learning means estimates an actual injection amount by the fuel injection based on the detected rotation increase amount and the slip ratio, The deviation amount is calculated based on a difference between the estimated injection amount and the command value.

In the above configuration, the actual injection amount is estimated using the actual slip rate and the detected rotation change amount ( rotation increase amount ). For this reason, the deviation | shift amount of the said injection characteristic can be converted into the difference of the estimated injection quantity and command value.

  According to a fourth aspect of the present invention, in the invention according to any one of the first to third aspects, the slip ratio calculating means is based on detection values of the rotational speed of the output shaft and the rotational speed of the driven shaft. The slip rate is calculated.

  In the above configuration, the slip ratio can be calculated appropriately.

  The invention according to claim 5 is the invention according to any one of claims 1 to 4, wherein the connection device transmits the rotation of the output shaft to the driven shaft via a viscous fluid, and the command In addition to the slip rate, the value is further set to an amount that is corrected to increase in accordance with either the temperature of the viscous fluid or its equivalent value, and the learning means adds to the calculated slip rate. The conversion is performed based on any of the above.

  In general, the viscosity of a viscous fluid increases as its temperature decreases. Further, even if the slip ratio between the output shaft and the driven shaft is the same, the influence on the output shaft from the driven shaft side is considered to be different due to the difference in viscosity. In this regard, in the above configuration, by setting the injection amount based on a parameter having a correlation with the viscosity of the viscous fluid, this injection amount is used as a command for a more appropriate injection amount necessary for generating the desired rotation change amount. Can be a value. Further, by using the detected rotation change amount, slip rate, and the above parameters, the shift amount can be learned with higher accuracy.

  According to a sixth aspect of the present invention, in the invention according to any one of the first to fifth aspects, the connection device rotates the output shaft by controlling a pressing force of a mechanical clutch against the output shaft and the driven shaft. Is transmitted to the driven shaft, and the calculating means calculates the slip ratio based on an operation amount for controlling the pressing force of the mechanical clutch.

  In the above configuration, when the pressing force of the mechanical clutch is different, the sliding state between the output shaft and the driven shaft is different. For this reason, the pressing force and the sliding state have a correlation. In this regard, in the above configuration, the slip ratio can be calculated based on the operation amount for controlling the pressing force.

  The invention according to claim 7 is the invention according to any one of claims 1 to 6, wherein the learning means performs the learning at the time of no-injection deceleration of the vehicle.

  In the above configuration, the amount of deviation can be learned based on the amount of rotation increase of the output shaft that accompanies injection by the injection means in order to learn the amount of deviation when the vehicle is decelerated without injection.

The invention of claim 8, wherein, in the invention of claim 7, wherein, prior Symbol injection means is characterized by injecting the said amount was increased injected with an equal volume divided.

  In the above configuration, in order to learn the shift amount for the micro injection, it is desirable that the injection amount by the injection unit is equivalent to the micro injection. Here, when the desired rotational change amount is a rotational change amount generated by micro injection at a predetermined slip ratio, the smaller the slip ratio is, the larger the injection amount of the micro injection is. The fuel is injected by the injection means. For this reason, under the condition that the actual slip rate is different from the predetermined slip rate, the injection amount by the injection means deviates from the minute injection amount. In this regard, in the above configuration, since the amount of fuel to be injected is divided into equal parts, even if the slip rate is smaller than the predetermined slip rate, the amount of fuel injected at a time through the fuel injection valve is minute. The injection amount can be equivalent.

  The predetermined slip ratio is desirably a slip ratio that is as large as possible that can occur in a situation where learning by the learning means is performed.

  The invention according to claim 9 is the invention according to any one of claims 1 to 8, wherein the vehicle is equipped with an automatic transmission, and the connecting device connects the automatic transmission and the output shaft. It is a torque converter to be connected.

  In the above configuration, since the torque converter is provided, the connection state between the output shaft and the driven shaft changes variously. For this reason, the said structure can show | play especially the effect of the invention of Claims 1-8 especially suitably.

(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 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.

  The fuel supply device 2 includes a fuel tank, a fuel pump that pumps fuel from the fuel tank, a common rail that supplies fuel under pressure from the fuel pump, and the like. On the other hand, the diesel engine 4 includes various actuators such as a fuel injection valve 6. The output shaft (crankshaft 8) of the diesel engine 4 is connected to the torque converter 10.

  Inside the torque converter 10, a pump impeller 12 and a turbine runner 14 that constitute a fluid coupling are provided to face each other, and a stator 16 that rectifies the flow of oil is provided between the pump impeller 12 and the turbine runner 14. Is provided. The pump impeller 12 is connected to the crankshaft 8, and the turbine runner 14 is connected to a driven shaft 18 that is an output shaft of the torque converter 10. Further, the torque converter 10 is provided with a lockup clutch 19 for engaging or disengaging between the crankshaft 8 and the driven shaft 18.

  The torque converter 10 is filled with hydraulic oil (viscous fluid), so that the rotation of the crankshaft 8 can be transmitted to the driven shaft 18 while sliding the driven shaft 18 with respect to the crankshaft 8. . When the crankshaft 8 and the driven shaft 18 are mechanically connected by the lockup clutch 19, the relative rotational speed between the crankshaft 8 and the driven shaft 18 becomes substantially zero.

  The driven shaft 18 is connected to the automatic transmission 20. The automatic transmission 20 changes the rotational speed of the driven shaft 18 and outputs it to the drive wheel side.

  The engine system includes, for example, a crank angle sensor 30 that detects the rotation angle of the crankshaft 8, a turbine rotation sensor 32 that detects the rotation angle of the driven shaft 18, and an oil temperature sensor that detects the temperature of hydraulic oil in the torque converter 10. 34. Various sensors such as an accelerator sensor 36 for detecting the operation amount of the accelerator pedal are provided.

  The electronic control unit (ECU 40) is composed mainly of a microcomputer, and drives the vehicle by operating the fuel supply device 2, the fuel injection valve 6, the lock-up clutch 19 and the like based on the detection values of the various sensors. It controls the force. For example, the fuel injection amount required for generating the output torque of the diesel engine 4 corresponding to the operation of the accelerator pedal is calculated based on the operation amount of the accelerator pedal and the rotation speed of the crankshaft 8, and the fuel is calculated based on this. By operating the injection valve 6, the output of the diesel engine 4 is controlled. Further, for example, by locking the lock-up clutch 19, the relative rotational speed between the crankshaft 8 and the driven shaft 18 becomes substantially zero, and torque loss when the output torque of the diesel engine 4 is transmitted to the driven shaft 18 is reduced. Reduce.

  Next, a process related to learning of a learning value for compensating for variations in injection characteristics of the fuel injection valve 6 according to the present embodiment will be described. In the present embodiment, learning of a learning value that compensates for variations in the injection characteristics of the fuel injection valve 6 when performing minute injection is performed. Here, the micro-injection is from the main injection such as pilot injection, pre-injection, and after-injection performed before and after the main injection, which is the main injection for generating the output torque required by the operation of the accelerator pedal. Also means a small amount of injection.

  Learning of the learning value is basically performed by estimating variation in actual injection characteristics based on the rotation state of the crankshaft 8 accompanying fuel injection. However, since the rotation state of the crankshaft 8 with respect to the same injection amount varies depending on the connection state between the crankshaft 8 and the driven shaft 18 by the torque converter 10, the actual injection amount is uniquely determined from the rotation state of the crankshaft 8. It cannot be determined.

  Thus, in the present embodiment, the relationship between the rotational state of the crankshaft 8 and the injection amount is excluded by eliminating the variation caused by the connection state of the torque converter 10 from the variation in the rotational state of the crankshaft 8 with respect to the same injection amount. Learning value is determined. Hereinafter, this will be described with reference to FIG.

  FIG. 2 shows a procedure of processing related to learning of learning values according to the present embodiment. This process is repeatedly executed by the ECU 40, for example, at a predetermined cycle.

  In this series of processing, first, in step S10, it is determined whether or not a learning condition is satisfied. The learning condition is that the accelerator pedal is released, the vehicle is in a deceleration state, and fuel injection control is performed without fuel injection control. By learning the learning value at the time of non-injection deceleration, it becomes possible to estimate the actual injection amount using the rotation increase amount of the crankshaft 8 by fuel injection for learning.

  Further, during no-injection deceleration, control for releasing the lock-up clutch 19 is not shown in order to suppress a shock from being transmitted to the vehicle due to a sudden increase in the output torque of the diesel engine 4 when the vehicle is reaccelerated. It is made in. For this reason, in the present embodiment, the learning value is learned when the crankshaft 8 and the driven shaft 18 are not connected so as not to slip, and the learning value can be learned with high accuracy. That is, when the lock-up clutch 19 is locked, the crankshaft 8, the driven shaft 18 and the drive wheel rotate as one huge rotating body, so the rotation state of the crankshaft 8 is It will be directly affected by the rotational fluctuation of the huge rotating body caused by torsional force and the like. On the other hand, when the lockup clutch 19 is released, the influence of the driven shaft 18 side on the rotation of the crankshaft 8 can be treated as a disturbance to the crankshaft 8. In addition, since slip is allowed between the crankshaft 8 and the driven shaft 18, rotational fluctuations on the driven shaft 18 side are transmitted to the crankshaft 8 in a smoothed manner. It is possible to suppress a decrease in learning accuracy due to rotational fluctuation on the side.

  In subsequent step S12, a basic quantity of single injection, which is a single fuel injection performed for learning, is calculated. This basic amount is an injection amount required by the above-described minute injection such as pilot injection.

  In the subsequent step S14, the slip ratio between the crankshaft 8 and the driven shaft 18 at the time of single injection is calculated. The slip rate may be any value as long as the deviation of the rotational speed of the driven shaft 18 with respect to the crankshaft 8 is arbitrarily quantified. In this embodiment, the slip rate is quantified in the manner shown in FIG. That is, using the rotational speed NE of the crankshaft 8 detected by the crank angle sensor 30 (step S30) and the rotational speed NO of the driven shaft 18 detected by the turbine rotation sensor 32 (step S32), the slip ratio SR. Is quantified by “SR = 100 × | NE−NO | / NE” (step S34).

  Subsequently, in step S16 of FIG. 2, it is determined whether or not the calculated slip ratio is within a slip ratio range in which the relationship between the single injection amount and the rotation increase amount of the crankshaft 8 is clear. It is desirable that the range of the slip ratio is determined except for a region where the slip ratio is extremely close to “0”. That is, in the region where the slip rate is extremely close to “0”, the influence of the driven shaft 18 side on the rotation of the crankshaft 8 can be treated as a disturbance, but the disturbance becomes large. For this reason, it is desirable to further improve the learning accuracy by excluding a region where the slip rate is extremely close to “0”.

  When it is determined that the slip ratio is within the above range, the temperature of the hydraulic oil of the torque converter 10 detected by the oil temperature sensor 34 is captured in step S18. In the subsequent step S20, the injection amount required to obtain the rotational increase amount (desired rotational increase amount) of the crankshaft 8 generated by performing the micro injection at a predetermined slip rate, and the micro injection. A correction amount for correcting the difference from the amount is calculated. That is, the amount of increase in the rotation of the crankshaft 8 with respect to the same injection amount varies due to the connection state between the crankshaft 8 and the driven shaft 18 by the torque converter 10, and thus a desired rotation state is generated in the actual connection state. The correction amount for performing the single injection with the injection amount for calculating is calculated.

  The calculation of the correction amount is performed based on the map shown in FIG. This map defines the relationship between the slip ratio, the oil temperature, and the correction amount. As shown in the figure, the correction amount increases as the slip ratio decreases. In other words, the smaller the slip ratio, the larger the injection amount for generating a desired rotation increase amount. This is because the influence of the driven shaft 18 on the crankshaft 8 is considered to increase as the slip ratio decreases. Further, the correction amount increases as the temperature of the hydraulic oil decreases. In other words, the lower the temperature of the hydraulic oil, the larger the injection amount for generating a desired rotation increase amount. This is because the lower the temperature of the hydraulic oil, the higher the viscosity, and the lower the temperature of the hydraulic oil, the greater the influence of the driven shaft 18 on the crankshaft 8 even if the slip ratio is constant.

  In order to avoid the correction amount from becoming a negative value, it is desirable that the predetermined slip ratio is as large as possible among the slip ratios assumed for learning. Thereby, it can avoid that the injection quantity after correction | amendment falls below micro injection quantity.

  Subsequently, in step S22 of FIG. 2, the single injection is performed by operating the fuel injection valve 6 desired to be learned according to the command value with the corrected injection amount as the command value. Specifically, a command injection period for the fuel injection valve 6 is calculated from the fuel pressure in the common rail and the corrected injection amount, and the fuel injection valve 6 is opened according to the command injection period. The calculation of the command injection period is performed on the assumption that the fuel injection valve 6 has a characteristic that is a predetermined reference. Here, it is desirable that the reference characteristic is a so-called central characteristic that is an averaged characteristic variation when the fuel injection valve 6 is mass-produced.

  In the subsequent step S24, the amount of increase in the rotational speed of the crankshaft 8 is detected. For example, when single injection is performed by the fuel injection valve 6 of the first cylinder, the rotational speed ω (i−1) before “720 ° CA” and the decrease speed “a” of the rotational speed before “720 ° CA”. Using the time t required for the rotation of “720 ° CA” until single injection, the rotational speed when single injection is not performed during single injection is “ω (i−1) + a × t”. . For this reason, using the rotational speed ω (i) at the time of single injection, the amount of increase in rotation accompanying single injection is “ω (i) −ω (i−1) −a × t”.

  Here, since the single injection in step S22 is the injection amount required to generate the desired rotational state at the actual slip rate, the rotation increase amount detected in step S24 and the desired rotation It is considered that the difference from the increase amount is caused by the variation in the injection characteristics of the fuel injection valve 6 (deviation from the reference characteristics). For this reason, the learning value can be learned by converting the difference between these rotational increases into the variation in the injection characteristics. This is the process shown in steps S26 and S28.

  That is, first, in step S26, the injection amount actually injected during the single injection is estimated. This is basically performed using the map shown in FIG. This map shows the relationship among the rotational speed, the injection amount, and the rotation increase amount when performing single injection at the time of non-injection deceleration for each of various slip rates. As shown in the figure, the amount of increase in rotation increases as the injection amount increases. Using this map, the actual injection amount can be calculated by inputting the slip rate calculated in step S14, the detected rotation increase amount, and the rotational speed at that time. However, as described above, the relationship between the rotation increase amount and the injection amount is not uniquely determined even if the slip ratio is constant, and varies depending on the oil temperature of the hydraulic oil of the torque converter 10. For this reason, the final injection amount is estimated by correcting the injection amount calculated by the map with the oil temperature. The correction at the oil temperature is performed using the map shown in FIG.

  Subsequently, in step S28 of FIG. 2, the learning value is learned. Here, the actual slip rate (slip rate calculated in step S14) and the injection amount (corrected injection amount used in step S22) for generating a desired rotation change amount at the oil temperature and the estimated injection above. The difference from the quantity is the variation in the injection characteristics. Then, a learning value is learned as a value for compensating for this variation. This may be a correction value for the command injection period or a correction value for the injection amount itself.

  In practice, since the relationship between the injection amount used in the process of step S22 and the command injection period changes according to the fuel pressure in the common rail, each learning value is learned according to the fuel pressure in the common rail. It is desirable.

  When the process of step S28 is completed in this way, or when a negative determination is made in steps S10 and S16, this series of processes is temporarily terminated.

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

  (1) The difference between the rotation increase amount detected when the injection is performed with the injection amount for setting the rotation increase amount of the crankshaft 8 to the desired increase amount and the desired rotation increase amount is used as a deviation amount of the injection characteristic. Converted. Thus, when the detected rotation increase amount deviates from the desired rotation increase amount, the difference can be considered to be caused by variations in the injection characteristics of the fuel injection valve 6. For this reason, the difference between the detected rotation increase amount and the desired rotation increase amount can be converted into the deviation amount of the injection characteristic with high accuracy, and the learning value can be learned with high accuracy.

  (2) The injection amount actually injected at the time of single injection was estimated, and the deviation amount of the injection characteristic was calculated as the difference between the injection amount command value and the estimated injection amount at the same slip ratio. Thereby, conversion to the deviation | shift amount of an injection characteristic can be performed appropriately.

  (3) An injection amount that generates a desired rotation increase amount is calculated according to the slip ratio and the temperature of the hydraulic oil. Thereby, it is possible to generate a more appropriate injection amount for generating a desired rotation increase amount.

  (4) By performing learning at the time of non-injection deceleration of the vehicle, even if the diesel engine 4 is a multi-cylinder engine, the amount of increase in rotation of the crankshaft can be easily identified as being due to single injection of a specific fuel injection valve 6 can do. Furthermore, since there is a region where the lock-up clutch 19 is released during non-injection deceleration, the learning value can be learned with high accuracy in this region.

  (5) By calculating the slip ratio based on the detected values of the rotation speed of the crankshaft 8 and the rotation speed of the driven shaft 18, the slip ratio can be calculated appropriately.

  (6) Targeted on vehicles equipped with automatic transmissions. In this case, since the connection state between the crankshaft 8 and the driven shaft 18 by the torque converter 10 varies in various ways, the above-described effects can be achieved particularly suitably.

(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 above embodiment, the injection amount is corrected in advance according to the slip ratio and the temperature of the hydraulic oil when performing the single injection. As a result, it is possible to suitably suppress the obstruction of the influence of the driven shaft 18 on the rotation of the crankshaft 8 in accurately detecting the amount of increase in rotation associated with the single injection. In other words, when single injection is performed with a small injection amount, the injection amount is very small. Therefore, when the slip ratio is small or the temperature of the hydraulic oil is low, the rotational increase amount associated with the single injection is determined as the driven shaft 18. Although it may be difficult to detect due to the influence of the side, such a problem can be avoided by increasing the injection amount.

  On the other hand, in view of the tendency that the relationship between the command injection period and the injection amount is not linear, it is desirable to approximate the single injection to the minute injection amount as much as possible when learning the learning value for the minute injection. In this regard, the above-described increase correction has a concern that the learning accuracy of the learning value in the micro injection is lowered because the fuel amount actually injected is deviated from the injection amount of the micro injection.

  Therefore, in the present embodiment, the corrected injection amount is divided into equal injection amounts corresponding to the injection amount of the minute injection, and the learning value is obtained by detecting the rotation increase amount of the crankshaft 8 at this time. learn. This will be described below with reference to FIG.

  FIG. 6 shows a learning processing procedure according to the present embodiment. This process is repeatedly executed by the ECU 40, for example, at a predetermined cycle. Incidentally, in FIG. 6, the same step number is attached | subjected about the step same as previous FIG. 2 for convenience.

  Also in this series of processing, the same processing as step S10 of FIG. 2 is performed. In the subsequent step S12a, a basic amount of fuel injection performed for learning is calculated.

  Subsequently, the processes of steps S14 to S20 of FIG. 2 are performed. In step S21, the number of divisions is calculated based on the corrected injection amount. This process is performed in order to approximate each injection amount to a minute injection when the corrected injection amount is divided and injected. This is, for example, when the corrected injection amount is n times or more and less than (n + 1) times “micro injection amount × X / 100” with reference to “X%: 0 << X ≦ 100” of the micro injection amount. This can be done by setting the number of divisions to “n”.

  In the subsequent step S22a, the fuel injection valve 6 that is desired to be learned is operated according to the command value with the injection amount divided into equal parts as the command value of each injection amount, so that “n” in a single combustion stroke. Implement fuel injections. Specifically, a command injection period for the fuel injection valve 6 is calculated from the fuel pressure in the common rail and the divided injection amount, and the fuel injection valve 6 is opened “n” times according to the command injection period. Actually, instead of setting the same command injection period for “n” times, for the second and subsequent injections, it is desirable to correct the command injection period by an interval from the preceding injection. That is, since the pulsation occurs in the fuel pressure in the common rail due to the previous injection, the actual injection amount may deviate from “(corrected injection amount) / n” if the command injection period is the same. In order to compensate for this, it is desirable to perform interval correction.

  When the fuel is thus injected, the processes of steps S24 to S28 in FIG. 2 are performed.

  According to the present embodiment described above, the following effects can be obtained in addition to the effects according to the above (1) to (6) of the first embodiment.

  (7) By dividing the corrected injection amount into equal parts and injecting the fuel, the amount of fuel injected at one time through the fuel injection valve 6 can be made equivalent to the minute injection amount, and as a result The learning value can be learned with high accuracy.

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

  In the present embodiment, the injection amount is simply corrected based only on the slip rate. Further, in the present embodiment, the correction of the injection amount shown in step S20 of FIG. 6 and the estimation of the injection amount shown in step S26 are performed using the same map shown in FIG. The map shown in FIG. 7 shows the relationship among the rotational speed, the rotational increase amount, the slip rate, and the injection amount. In FIG. 7, the rotation increase amount generated by the injection amount Qa of the minute injection at the predetermined slip ratio SR0 is shown as a desired rotation increase amount ΔNEa. Here, when the actual slip rate is different from the slip rate SR0, the injection amount Qa is corrected so that the desired rotation increase amount ΔNEa is obtained.

  By performing the fuel injection with the corrected injection amount in this way, when the detected rotation increase amount deviates from the desired rotation increase amount ΔNEa, it can be considered that this shift is caused by variations in the injection characteristics of the fuel injection valve 6. it can. FIG. 7 illustrates a case where the detected rotation increase amount ΔNEr is smaller than the desired rotation increase amount ΔNEa.

  When converting the difference between the detected rotation increase amount ΔNEa and the desired rotation increase amount ΔNEr into the injection amount difference, the injection amount that generates the rotation increase amount ΔNEr at the actual slip rate is calculated. For example, when the actual slip rate is the slip rate SR1, the difference between the injection amount Qbr that generates the detected rotation increase amount ΔNEr and the command value (injection amount Qb) of the injection amount quantifies the variation in the injection characteristics Will be. Alternatively, an injection amount difference that generates the rotation increase amounts ΔNEa and ΔNEr at an arbitrary slip rate may be calculated. FIG. 7 shows the injection amounts Qa and Qar at the slip rate SR0, the injection amounts Qb and Qbr at the slip rate SR1, and the injection amounts Qc and Qcr at the slip rate SR2.

  However, as illustrated in FIG. 7, when the inclination of the rotational increase amount with respect to the injection amount tends to change according to the slip rate, based on the injection amount difference in each of these slip rates and the actual slip rate, It is desirable to calculate the injection amount difference. Here, the actual slip ratio is a parameter for correcting a deviation between the injection amount difference calculated at an arbitrary slip ratio and the injection amount difference at the actual slip ratio.

  Also according to the present embodiment described above, it is possible to obtain an effect according to the effect other than the above (3) of the first embodiment and the effect (7) of the previous second embodiment. .

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

  In the present embodiment, when the accelerator pedal is released and the injection amount becomes zero, the pressing force of the lockup clutch 19 against the crankshaft 8 and the driven shaft 18 is slightly weakened, and the space between the crankshaft 8 and the driven shaft 18 is reduced. By performing flex lockup control that allows slipping, the fuel cut control time is extended. That is, the fuel cut control at the time of deceleration is stopped when the rotational speed of the crankshaft 8 becomes a predetermined value or less, so that the rotational speed of the crankshaft 8 is not suddenly reduced by the flex lockup control. To.

  Furthermore, in this embodiment, the slip rate is calculated in the manner shown in FIG. 8 during the flex lockup control.

  That is, here, in step S40, a duty value that is an operation amount at the time of flex lockup control is fetched. Since this duty value determines the pressing force of the lockup clutch 19 against the crankshaft 8 and the driven shaft 18, the slip ratio is calculated based on this duty value. More specifically, as shown in step S40, the slip ratio SR is map-calculated based on this duty value. In actuality, even if the pressing force is the same, the slip ratio may vary depending on the rotational speed of the crankshaft 8, etc., so the slip ratio is calculated by taking into account the rotational speed of the crankshaft 8 in addition to the duty value. It is desirable to do.

  Also according to the present embodiment described above, it is possible to obtain the effects according to the above (1) to (4) and (6) of the first embodiment and the above (7) of the second embodiment. Can do.

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

  -You may apply the method of the said 3rd Embodiment and 4th Embodiment to previous 1st Embodiment.

  -In 4th Embodiment, even if it is the same pressing force, you may consider the temperature of hydraulic fluid in the case of calculation of a slip ratio, considering that slip ratio may differ, so that the viscosity of hydraulic fluid is high.

  -The method of calculating the slip ratio is not limited to the one exemplified in the above embodiments. For example, the rotational speed of the driven shaft 18 may be detected from the gear ratio of the automatic transmission 20 and the output rotational speed of the automatic transmission 20, and the slip ratio may be calculated based on this and the rotational speed of the crankshaft 8. Further, for example, when the lockup clutch 19 is released, the slip ratio may be calculated from the temperature of the hydraulic oil at the time of release in view of the fact that the slip ratio has a particularly strong correlation with the viscosity of the hydraulic oil.

  The parameter having a correlation with the viscosity of the hydraulic oil in the torque converter 10 is not limited to the temperature of the hydraulic oil. For example, since the coolant temperature of the diesel engine 4 has a correlation with the temperature of the hydraulic oil, this is a parameter having a correlation with the viscosity of the hydraulic oil.

  The method for increasing and correcting the desired injection amount (the injection amount to be learned) in order to generate the desired rotation change amount is not limited to the one exemplified in the above embodiment. In short, any increase correction is required to obtain an injection amount that can generate a detectable rotation change amount.

  The method for converting the difference between the detected rotation increase amount and the desired rotation increase amount into the deviation amount of the injection characteristic is not limited to the above. For example, the learning value may be map-calculated from the difference between the detected rotational increase amount and the desired rotational increase amount. At this time, it is desirable to map the learning value based on the slip rate in addition to the difference in the rotation increase amount. Thereby, as illustrated in FIG. 7, the learning value can be learned with higher accuracy even when the inclinations of the rotational increase amount with respect to the injection amount are different from each other according to the slip ratio. Furthermore, it is more desirable to map the learning value based on the oil temperature in addition to the difference in the rotational increase amount and the slip rate.

  The injection amount estimation method based on the rotation change amount of the crankshaft 8 having a correlation with the injection amount is not limited to the one using the rotation increase amount exemplified in the above embodiment. For example, the output torque of the diesel engine 4 calculated in a mode exemplified in JP-A-2005-36788 may be used.

  In each of the above embodiments, the vehicle on which the automatic transmission is mounted is targeted. However, the present invention is not limited to this and may be a manual transmission vehicle, for example. Even in this case, by applying the present invention, the learning value can be learned with high accuracy even in the half-clutch state, so that the learning opportunities can be increased.

  The fuel injection valve 6 is not limited to uniquely determining the injection amount based on the fuel pressure and the command injection period. For example, as described in US Pat. No. 6,520,423, if the fuel injection valve 6 is capable of continuously adjusting the lift amount of the nozzle needle in accordance with the displacement of the actuator, the injection period and the fuel pressure Therefore, the injection amount cannot be determined uniquely. In this case, the operation amount of the fuel injection valve is determined by, for example, the amount of energy applied to the actuator and the period during which energy is applied (injection period), and the injection amount is determined by the fuel pressure, the energy amount, and the injection period. . For this reason, it is desirable to learn a learning value for at least one of the energy amount and the injection period.

  In each of the above embodiments, learning of the deviation amount of the injection characteristic is not limited to learning a value (a form of the deviation amount of the injection characteristic) that compensates for variations in the injection characteristic, but the deviation amount itself from the reference of the injection characteristic. May be learning. In this case, the ECU 40 may calculate a correction value for compensating for variations in injection characteristics based on the amount of deviation each time fuel is injected.

  The onboard internal combustion engine is not limited to a diesel engine, and may be a gasoline engine.

The figure which shows the whole structure of the engine system concerning 1st Embodiment. The flowchart which shows the procedure of the learning process concerning the embodiment. The flowchart which shows the procedure of the process of calculation of the slip ratio concerning the embodiment. The figure which shows the map for calculating the corrected amount of injection quantity in the same embodiment. The figure which shows the map for estimating the injection quantity in the same embodiment. The flowchart which shows the procedure of the learning process concerning 2nd Embodiment. The figure which shows the map used for learning in 3rd Embodiment. The flowchart which shows the procedure of the process of calculation of the slip ratio concerning 4th Embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 4 ... Diesel engine, 6 ... Fuel injection valve, 10 ... Torque converter, 18 ... Driven shaft, 19 ... Lock-up clutch, 20 ... Automatic transmission, 40 ... ECU.

Claims (9)

In a fuel injection control device mounted on a vehicle provided with a connecting device capable of transmitting rotation of the output shaft to the driven shaft while sliding a driven shaft connected to drive wheels with respect to an output shaft of an internal combustion engine,
The internal combustion engine is a diesel engine;
A calculating means for calculating a slip ratio indicating a rotational deviation between the output shaft and the driven shaft;
Injection means for operating the fuel injection valve of the internal combustion engine in accordance with a command value of a predetermined injection amount to inject fuel;
Learning means for learning a deviation amount of the injection characteristic of the fuel injection valve based on the rotation increase amount of the output shaft detected with the fuel injection;
The learning means, a pilot injection, learning the deviation amount of the injection characteristics of the time pre-injection and an after either a is said infinitesimal amount than the main become injection for producing an output torque of the internal combustion engine injection injection In order to generate a predetermined amount of rotation increase for use in learning of the deviation amount, the injection amount that is the learning target of the deviation amount is increased and corrected according to the slip ratio. Means for setting as a command value; and means for converting a difference between the detected rotation increase amount and the predetermined rotation increase amount into a deviation amount of the injection characteristic based on the slip ratio. A fuel injection control device.   2. The fuel injection control device according to claim 1, wherein the injection means performs the fuel injection when slippage is allowed between the output shaft and the driven shaft. The learning means estimates an actual injection amount by the fuel injection based on the detected rotation increase amount and the slip ratio, and calculates the deviation amount based on a difference between the estimated injection amount and the command value. The fuel injection control device according to claim 1, wherein the fuel injection control device calculates the fuel injection.   The fuel according to any one of claims 1 to 3, wherein the slip ratio calculating means calculates the slip ratio based on detected values of a rotation speed of the output shaft and a rotation speed of the driven shaft. Injection control device. The connection device transmits the rotation of the output shaft to the driven shaft via a viscous fluid,
The command value is set to an amount that is corrected to increase in accordance with either the temperature of the viscous fluid and its equivalent value in addition to the slip ratio,
5. The fuel injection control device according to claim 1, wherein the learning unit performs the conversion based on any one of the calculated slip rates in addition to the calculated slip rate. The connection device is configured to transmit rotation of the output shaft to the driven shaft by controlling a pressing force of a mechanical clutch against the output shaft and the driven shaft.
The fuel injection control device according to claim 1, wherein the calculation unit calculates the slip ratio based on an operation amount for controlling a pressing force of the mechanical clutch.   The fuel injection control device according to claim 1, wherein the learning unit performs the learning when the vehicle is decelerated. Before SL injecting means, the increased amount of injected fuel injection amount control device according to claim 7, wherein the injecting and equal amounts divide. The vehicle is equipped with an automatic transmission,
The fuel injection control device according to claim 1, wherein the connection device is a torque converter that connects the automatic transmission and the output shaft.

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