JP4375123B2 - Fuel injection control device for direct injection internal combustion engine - Google Patents

Description

  The present invention relates to a fuel injection control device for a direct injection internal combustion engine that performs fuel injection by compensating for an error in the amount of fuel injected from a fuel injection valve into a cylinder based on a pressure factor in fuel injection.

In fuel injection control in a direct-injection internal combustion engine, the fuel injection amount is calculated from the operating state of the internal combustion engine based on a map set in advance by experiments under standard in-cylinder pressure. Then, the fuel injection amount Tp is corrected (Tp / K) based on the fuel injection rate K obtained from the differential pressure between the actual in-cylinder pressure and the actual fuel pressure, and used for actual fuel injection control (for example, Patent Document 1).
Japanese Patent Laid-Open No. 9-256886 (page 4, FIG. 3)

  However, in practice, it has been found that the fuel injection rate does not contribute uniformly to the fuel injection amount in the process of fuel injection. Accordingly, an error occurs only by the primary calculation (Tp / K) as in the prior art, and highly accurate fuel injection control cannot be performed, and it is necessary to consider the difference in contribution of the fuel injection rate in the fuel injection process.

  From this, by calculating the fuel injection correction amount according to the difference in contribution of the fuel injection rate in the fuel injection process, it is possible to appropriately correct the fuel injection amount based on the pressure factor difference in the direct injection internal combustion engine. As a result, the control accuracy of the fuel injection amount is improved.

Further, it has been found that the fuel injection control for correcting the fuel injection amount in consideration of the difference in contribution of the fuel injection rate can be further improved.
An object of the present invention is to realize highly accurate fuel injection control in a direct injection internal combustion engine in consideration of the difference in contribution of the fuel injection rate.

In the following, means for achieving the above object and its effects are described.
A fuel injection control device for a direct injection type internal combustion engine according to claim 1, wherein the direct injection type internal combustion engine performs fuel injection by compensating for a fuel injection amount error from a fuel injection valve into a cylinder generated based on a pressure factor in fuel injection. fuel the fuel injection control system, the fuel injection rate in the fuel injection rate compensation correction amount for compensating for the fuel injection quantity error corresponding to the change in the fuel injection rate arising under pressure factors, the fuel injection process A correction amount calculating means for calculating according to a difference in contribution to the injection amount, and a fuel injection rate compensation correction amount calculated by the correction amount calculating means for the fuel injection time based on the estimated fuel injection rate at the time of fuel injection. By converting, a fuel injection rate compensation correction time calculating means for calculating a fuel injection rate compensation correction time, and a fuel injection time corresponding to the required fuel injection amount based on the operating state of the direct injection internal combustion engine are calculated. The fuel injection time calculated by the fuel injection time calculation means is corrected by a correction time including the fuel injection time calculation means for performing the fuel injection rate compensation correction time calculated by the fuel injection rate compensation correction time calculation means. A fuel injection time correction means for performing the fuel injection time division, and the correction amount calculation means is divided into an on-off valve drive transient period and a fully open period of the fuel injection valve according to a difference in contribution of the fuel injection rate in the fuel injection process. A transition period fuel injection rate compensation correction amount that compensates for a fuel injection amount error in accordance with a change in fuel injection rate that occurs based on the pressure factor in the on-off valve drive transition period, and the pressure factor in the fully open period A full-open period fuel injection rate compensation correction amount that compensates for a fuel injection amount error according to a change in the fuel injection rate that occurs based on the calculated fuel injection rate compensation correction amount is calculated .

  Thus, the correction amount calculation means calculates the fuel injection rate compensation correction amount for compensating the fuel injection amount error in accordance with the difference in contribution of the fuel injection rate in the fuel injection process. This fuel injection rate compensation correction amount is converted into fuel injection rate compensation correction time by the fuel injection rate compensation correction time calculation means based on the estimated fuel injection rate at the time of fuel injection. Then, using the correction time including this fuel injection rate compensation correction time, the fuel injection time correction means corrects the fuel injection time corresponding to the required fuel injection amount.

Thus, according to the difference in the contribution of the fuel injection rate in the fuel injection process, the fuel injection valve can be divided into an on-off valve drive transition period and a fully open period. Then, by calculating the transition period fuel injection rate compensation correction amount and the full-open period fuel injection rate compensation correction amount in each category, an accurate fuel injection rate compensation correction amount is obtained, and the control accuracy of the fuel injection amount is improved. become. Therefore , a correction amount calculating means for calculating a fuel injection rate compensation correction amount (transient fuel injection rate compensation correction amount and full-open period fuel injection rate compensation correction amount) according to the difference in contribution of the fuel injection rate in the fuel injection process is provided. As a result , the fuel injection amount can be appropriately corrected based on the difference in pressure factors, and the control accuracy of the fuel injection amount can be improved.

  The fuel injection rate compensation correction amount is not directly used to correct the fuel injection amount, but is a fuel injection rate compensation correction obtained by time-converting the fuel injection rate compensation correction amount based on the estimated fuel injection rate at the time of fuel injection. Correction for fuel injection time is performed in time. Therefore, it is possible to set an accurate fuel injection time that matches the required fuel injection amount in accordance with the actual situation at the time of fuel injection.

As a result, in the direct injection internal combustion engine, highly accurate fuel injection control can be realized in consideration of the difference in contribution of the fuel injection rate.
3. A fuel injection control device for a direct injection internal combustion engine according to claim 2, wherein the direct injection internal combustion engine performs fuel injection by compensating for a fuel injection amount error from a fuel injection valve into a cylinder generated based on a pressure factor in fuel injection. The fuel injection control apparatus according to claim 1, wherein the valve opening timing compensation correction is performed to calculate a valve opening timing compensation correction time that compensates for a fuel injection amount error in accordance with a change in the valve opening timing of the fuel injection valve that occurs based on the pressure factor. and time calculation means, the fuel injection rate compensation correction amount for compensating for the fuel injection quantity error corresponding to the change in the fuel injection rate arising under the pressure factors, contributing to the fuel injection quantity of the fuel injection rate in the fuel injection process Correction amount calculation means calculated according to the difference between the two, and the fuel injection rate compensation correction amount calculated by the correction amount calculation means is converted into fuel injection time based on the estimated fuel injection rate at the time of fuel injection The fuel injection rate compensation correction time calculating means for calculating the fuel injection rate compensation correction time, and the fuel injection time calculation for calculating the fuel injection time corresponding to the required fuel injection amount based on the operating state of the direct injection internal combustion engine And a correction time including a valve opening timing compensation correction time calculated by the valve opening timing compensation correction time calculation means and a fuel injection rate compensation correction time calculated by the fuel injection rate compensation correction time calculation means. And a fuel injection time correcting means for correcting the fuel injection time calculated by the fuel injection time calculating means, the correction amount calculating means according to the difference in contribution of the fuel injection rate in the fuel injection process, A fuel injection amount error corresponding to a change in the fuel injection rate caused by the pressure factor during the on-off valve drive transition period is compensated by dividing into a fuel injection valve on-off valve drive transition period and a fully open period. A transition period fuel injection rate compensation correction amount and a fully open period fuel injection rate compensation correction amount that compensates for a fuel injection amount error in accordance with a change in the fuel injection rate that occurs based on the pressure factor in the fully open period; The fuel injection rate compensation correction amount is used .

  By providing the valve opening timing compensation correction time calculation means, the valve opening timing compensation correction time for compensating for the fuel injection amount error in accordance with the change in the valve opening timing of the fuel injector caused based on the pressure factor is calculated. The fuel injection time is corrected by a correction time including the valve opening timing compensation correction time and the fuel injection rate compensation correction time described above.

  Depending on the fuel injection valve, the valve opening timing may change due to a change in pressure factor. In such a case, the valve opening timing compensation correction time calculation means obtains the valve opening timing compensation correction time, and corrects the fuel injection time together with the fuel injection rate compensation correction time described in claim 1 to obtain a pressure factor. Accordingly, the fuel injection amount can be appropriately corrected based on the difference, and the control accuracy of the fuel injection amount can be improved.

  Since the fuel injection time is corrected by the correction time including the valve opening timing compensation correction time and the fuel injection rate compensation correction time, an accurate fuel that matches the required fuel injection amount corresponding to the actual fuel injection situation The injection time can be set.

As a result, in the direct injection internal combustion engine, highly accurate fuel injection control can be realized in consideration of the difference in contribution of the fuel injection rate.
The fuel injection control device for a direct injection internal combustion engine according to claim 3, wherein the estimated fuel injection rate is a map in which the in-cylinder pressure, the fuel pressure, and the required fuel injection amount are parameters in advance. From the actual in-cylinder pressure at the time of fuel injection, fuel pressure, and the required fuel injection amount.

  By preparing such a map in advance, it is possible to easily and accurately convert the fuel injection rate compensation correction amount into the fuel injection rate compensation correction time according to the actual fuel injection situation. In a direct injection internal combustion engine, highly accurate fuel injection control can be realized in consideration of the difference in contribution of the fuel injection rate.

In a fuel injection control device for a direct injection internal combustion engine according to a fourth aspect, in any one of the first to third aspects, the pressure factors are an in-cylinder pressure and a fuel pressure.
More specifically, in-cylinder pressure and fuel pressure are used as pressure factors. With this configuration, the fuel injection amount can be appropriately corrected based on the difference between the in-cylinder pressure and the fuel pressure, and the control accuracy of the fuel injection amount can be improved.

6. The fuel injection control device for a direct injection internal combustion engine according to claim 5 , wherein the pressure factors are in-cylinder pressure and fuel pressure, and the valve opening timing compensation correction time calculating means The timing compensation correction time is calculated based on the product of the difference between the actual in-cylinder pressure and the standard in-cylinder pressure at the time of fuel injection and the injection timing correction coefficient obtained based on the actual fuel pressure value. Features.

  The valve opening timing compensation correction time is calculated based on the product of the difference between the actual in-cylinder pressure and the standard in-cylinder pressure at the time of fuel injection and the injection timing correction coefficient obtained based on the actual fuel pressure value. can do. By correcting the fuel injection time by the correction time including the valve opening timing compensation correction time and the fuel injection rate compensation correction time obtained in this way, the fuel injection amount is appropriately corrected based on the difference in pressure factors. As a result, the control accuracy of the fuel injection amount can be improved.

In the fuel injection control device for a direct injection internal combustion engine according to claim 6 , in any one of claims 1 to 5 , the pressure factors are in-cylinder pressure and fuel pressure, and the correction amount calculating means Based on the ratio between the pressure difference between the fuel pressure and the actual in-cylinder pressure at the time of fuel injection and the pressure difference between the actual fuel pressure and the standard in-cylinder pressure, the standard fuel injection rate and the actual fuel injection rate A change fuel injection rate ratio representing a ratio between the injection rate difference and the standard fuel injection rate is calculated, and the full-open period fuel injection rate compensation correction amount is calculated based on the relationship between the change fuel injection rate ratio and a primary expression. The fuel injection rate compensation correction amount during the transition period is calculated based on the relationship between the change fuel injection rate ratio and a quadratic expression.

  As described above, when calculating the transition period fuel injection rate compensation correction amount and the fully open period fuel injection rate compensation correction amount, the transient period fuel injection rate compensation correction amount is calculated based on the relationship between the change fuel injection rate ratio and the quadratic equation. The full-open period fuel injection rate compensation correction amount can be calculated based on the relationship between the change fuel injection rate ratio and the linear expression. Thus, the fuel injection rate compensation correction amount obtained by adding these correction amounts becomes an accurate correction amount, and the control accuracy of the fuel injection amount is improved.

It fuel injection control apparatus for a direct injection internal combustion engine according to claim 7, in claim 3, 5 or 6, the actual in-cylinder pressure during the fuel injection is an estimate or measured values at the time the fuel injection It is characterized by.

  The actual in-cylinder pressure at the time of fuel injection may be an estimated value or may be obtained from actual measurement at the time of injection.

[Embodiment 1]
FIG. 1 is a schematic configuration diagram of a vehicle diesel engine and an engine control device to which the above-described invention is applied.

  The diesel engine 2 is an engine having a plurality of cylinders, for example, 4 cylinders or 6 cylinders. The combustion chamber 4 of each cylinder is connected to a surge tank 12 via an intake port 8 and an intake manifold 10 that are opened and closed by an intake valve 6. The surge tank 12 is supplied with air from the air cleaner or the supercharger side via the intake passage 14. The surge tank 12 is supplied with EGR gas from an exhaust gas recirculation (hereinafter referred to as “EGR”) path 16. A throttle valve 18 is disposed in the intake path 14, and an intake air temperature sensor 20 is disposed between the throttle valve 18 and the surge tank 12. The throttle valve 18 is provided with a throttle opening sensor 18a for detecting the throttle opening and a motor 18b for driving the valve, and the surge tank 12 has an intake pressure sensor for detecting the internal intake pressure Pin. 21 is provided.

  The combustion chamber 4 discharges exhaust gas to the exhaust purification catalyst or the supercharger side through an exhaust port 24 opened and closed by an exhaust valve 22 and an exhaust manifold 26. The exhaust manifold 26 is supplied with exhaust gas as EGR gas to the EGR path 16.

  A fuel injection valve 28 provided for each cylinder and directly injecting fuel into each combustion chamber 4 is connected to a common rail 32 via a fuel supply pipe 30. Fuel is supplied into the common rail 32 from an electrically controlled discharge variable fuel pump 34, and the high-pressure fuel supplied from the fuel pump 34 into the common rail 32 is supplied to each fuel injection valve 28 via each fuel supply pipe 30. Distributed supply. A fuel pressure sensor 36 for detecting a fuel pressure Pf (so-called rail pressure) is attached to the common rail 32.

  An electronic control unit (hereinafter referred to as “ECU”) 40 is mainly configured by a digital computer including a CPU, a ROM, a RAM, and the like, and a drive circuit for driving each device. The ECU 40 reads signals from the intake air temperature sensor 20, the intake pressure sensor 21, the fuel pressure sensor 36, and the throttle opening sensor 18a. Further, signals are read from an accelerator opening sensor 44 that detects the amount of depression of the accelerator pedal 42 (accelerator opening ACCP) and a cooling water temperature sensor 46 that detects the cooling water temperature THW of the diesel engine 2. Further, an engine speed sensor 50 for detecting the rotational speed of the crankshaft 48 (hereinafter referred to as “engine speed NE”), the rotational phase of the crankshaft 48 or the rotational phase of the intake cam, and the reference crank angle signal G2 are detected. Is read from the cylinder discrimination sensor 52 that outputs.

  The ECU 40 executes fuel injection control by the fuel injection valve 28 based on the engine operation state and the operation state obtained from these signals. In addition, throttle opening control by the motor 18b, discharge amount control of the fuel pump 34, and the like are executed.

  Here, the structure and operation of the fuel injection valve 28 will be described. As shown in FIG. 2, the fuel injection valve 28 includes a main body 62, a needle valve 64, and a coil spring 66. The needle valve 64 and the coil spring 66 are housed inside the main body 62, and a fuel injection hole 68 is formed at the tip of the main body 62. The needle valve 64 can move forward and backward in the axial direction, and closes the fuel injection hole 68 by sitting on the seat portion 70 when moving forward, and opens the fuel injection hole 68 by moving away from the seat portion 70 when moving backward. The coil spring 66 urges the needle valve 64 in the valve closing direction, that is, in the direction of the fuel injection hole 68. A sac chamber 72 is formed between the fuel injection hole 68 and the seat portion 70.

  Further, the main body 62 is formed with a first fuel supply path 74, a second fuel supply path 76 branched from the first fuel supply path 74, a fuel discharge path 78, a control chamber 80, and a fuel reservoir 82. The first fuel supply path 74 guides high-pressure fuel supplied from the common rail 32 to a predetermined pressure through the fuel supply pipe 30 (FIG. 1) and supplied to the fuel reservoir 82. The second fuel supply path 76 guides the high pressure fuel from the common rail 32 to the control chamber 80. The fuel discharge path 78 functions to discharge high-pressure fuel in the control chamber 80 when the pressure in the control chamber 80 is reduced. The second fuel supply passage 76 is provided with an inlet orifice 76a to determine the amount of fuel flowing into the control chamber 80. An outlet orifice 78 a is provided in the fuel discharge path 78 to determine the amount of fuel discharged from the control chamber 80. The passage sectional area of the outlet orifice 78a is set larger than that of the inlet orifice 76a.

  The needle valve 64 includes a main piston 64a and a sub piston 64b. The main piston 64a receives the fuel pressure from the control chamber 80 and generates a driving force Fm in the valve closing direction of the needle valve 64. The sub-piston 64b receives the fuel pressure from the fuel reservoir 82 and generates a driving force Fs for opening the needle valve 64 in the valve opening direction. The pressure receiving area of the fuel pressure received by the sub piston 64b from the fuel reservoir 82 is set smaller than the pressure receiving area of the fuel pressure received by the main piston 64a from the control chamber 80.

Here, assuming that the urging force Fc is applied from the coil spring 66, Fm + Fc> Fs and Fc <Fs are set in a steady state.
A discharge pressure control valve 84 for controlling opening and closing of the fuel discharge path 78 is provided at the outlet orifice 78a portion. When the exhaust pressure control valve 84 is closed, it functions to prevent discharge of high-pressure fuel from the control chamber 80 and maintain the inside of the control chamber 80 in a high-pressure state. When the exhaust pressure control valve 84 is opened, high pressure fuel is discharged from the control chamber 80, so that the function of reducing the pressure in the control chamber 80 is achieved. The exhaust pressure control valve 84 is constituted by an electromagnetic valve.

  If the exhaust pressure control valve 84 is driven to close, the fuel pressure in the control chamber 80 has risen, so Fm + Fc> Fs, and the main piston 64a is pushed toward the fuel injection hole 68 and the needle valve 64 is driven. Is seated on the seat portion 70 and the fuel injection valve 28 is kept closed.

  When the exhaust pressure control valve 84 is driven to open by the ECU 40, the fuel in the control chamber 80 is discharged through the fuel discharge path 78, and the passage sectional area of the outlet orifice 78a is set larger than the inlet orifice 76a. Therefore, the fuel pressure in the control chamber 80 decreases. For this reason, the driving force Fm in the valve closing direction becomes small.

  Thus, when Fm + Fc <Fs, the needle valve 64 starts to lift and is separated from the seat portion 70, so that fuel injection is started from the fuel injection hole 68. The fuel injection rate (mm 3 / μsec) gradually increases from the lift start to the maximum lift (full lift), and reaches the maximum fuel injection rate when fully opened, that is, at the maximum lift.

  When the valve is closed, the exhaust pressure control valve 84 is driven to close by the ECU 40, the fuel discharge path 78 is closed, the fuel pressure in the control chamber 80 rises, and the lift amount of the needle valve 64 is increased by Fm + Fc> Fs. The fuel injection from the fuel injection hole 68 stops when the seat becomes smaller and finally sits on the seat portion 70.

  Next, fuel injection control processing in the control executed by the ECU in the present embodiment will be described. 3 and 4 show flowcharts of the fuel injection control process. This process is a cycle of the fuel injection interval, and if it is a four-cylinder engine, an interruption is executed every 180 ° CA (CA: crank angle). The steps in the flowchart corresponding to the individual processing contents are represented by “S˜”.

  When this process is started, first, a basic fuel injection amount Qbs (mm3) per injection is set (S102). For example, the basic fuel injection amount Qbs is obtained from the accelerator opening ACCP and the engine speed NE according to the governor pattern stored in the ECU 40.

  Next, the basic fuel injection amount Qbs is calculated from the basic fuel injection amount Qbs based on the fuel injection time conversion map Mapts shown by the solid line in FIG. 5 (S104). For example, if the basic fuel injection amount Qbs = QA, the basic fuel injection time Tbs = TA is obtained as shown in FIG.

  This fuel injection time conversion map Mapts is previously mapped by measuring the relationship between the fuel injection amount and the fuel injection time by changing the fuel pressure Pf under the standard in-cylinder pressure Ps (for example, 1 MPa) using a standard fuel injection valve. It is a thing. FIG. 5 shows the relationship between the fuel injection amount and the fuel injection time under the current fuel pressure Pf. When the fuel pressure Pf changes, the solid line portion also changes.

  Next, the fuel injection timing θi is set as an advance value (° CA) with respect to a reference crank angle such as TDC (S106). This is set from the fuel injection timing map based on the basic fuel injection amount Qbs (or basic fuel injection time Tbs) and the engine speed NE. This fuel injection timing map is set based on experiments and the like in advance according to the type of engine for optimal combustion.

  When the fuel injection timing θi is set, the volume ratio Rv of the combustion chamber 4 at the fuel injection timing θi is calculated based on the fuel injection timing θi from the volume ratio map Mapvr shown in FIG. 6 (S108). . For example, if the fuel injection timing θi = θA, the volume ratio Rv = RA is obtained as shown in FIG.

  This volume ratio map Mapvr represents the ratio Vm / Vi between the maximum volume Vm of the combustion chamber 4 and the volume Vi of the combustion chamber 4 at the corresponding crank angle, and is set by theoretical calculation or experiment. .

  When the volume ratio Rv is obtained, the in-cylinder pressure Pic at the start of fuel injection is calculated as shown in Expression 1 based on the volume ratio Rv and the intake pressure Pin detected by the intake pressure sensor 21 (S110).

[Formula 1] Pic ← Rv × Pin
This in-cylinder pressure Pic at the start of fuel injection represents the atmospheric pressure in the combustion chamber 4 when fuel injection is started from the corresponding fuel injection valve 28 in the cylinder that is the current fuel injection target.

Next, the differential pressure ratio Rdp is calculated by Equation 2 (S112).
[Formula 2] Rdp <-(Pf-Pic) / (Pf-Ps)
Here, the right side of Expression 2 represents the ratio between the differential pressure (Pf−Pic) generated in the fuel injection valve 28 at the start of fuel injection and the differential pressure (Pf−Ps) in the standard state.

  Next, the fuel injection amount Qfl at the break point E of the fuel injection time conversion map Mapts shown by the solid line in FIG. 5 is obtained from the break point map Mapqfl based on the fuel pressure Pf (S114). This break point map Mapqfl is expressed as shown in FIG. 7, for example.

  As described in FIG. 2, the fuel injection valve 28 is not fully injected (full lift) at the start of fuel injection and does not inject fuel, but takes time from the start of opening to the full opening. Also, when closing, it takes time from full opening to full closing, not instant closing. FIG. 8 shows this phenomenon in relation to the fuel injection rate (mm 3 / μsec). Since such an on-off valve drive transition period exists, as shown in FIG. 5, a breakpoint E occurs where the relationship of the basic fuel injection time Tbs to the basic fuel injection amount Qbs changes discontinuously. The fuel injection amount at the break point E is set as the break point injection amount Qfl, and the relationship with the fuel pressure Pf is previously set as a break point map Mapqfl (FIG. 7) through experiments.

Next, based on the differential pressure ratio Rdp, the changed fuel injection rate ratio Rh is calculated as shown in Equation 3 (S116).
[Formula 3] Rh ← 1-√ (Rdp)
Note that “√ ()” on the right side represents an operator for calculating the square root of the value in () as displayed in step S116 in FIG.

  Here, it is assumed that there is a difference between the actual fuel injection rate pattern (solid line) and the standard fuel injection rate pattern (dashed line) in one injection as shown in FIG. The difference between the actual injection rate rq during the fully open period and the standard injection rate rQs is represented by “rQs−rq”. The ratio between the difference (rQs−rq) and the standard injection rate rQs is calculated as shown in Equation 4.

[Formula 4] (rQs−rq) / rQs = 1−rq / rQs
Of these, the square of the actual and standard injection rate ratio (rq / rQs) is known to be equal to the differential pressure ratio Rdp due to a physical relationship.

  Therefore, the equation 3 is equivalent to the equation 4, and the changed fuel injection rate ratio Rh represented by the equation 3 indicates the rate of change of the actual injection rate rq with respect to the standard injection rate rQs.

Next, it is determined whether or not the basic fuel injection amount Qbs is less than the break point injection amount Qfl (S118).
Here, first, a case where Qbs ≧ Qfl (YES in S118) will be described. In this case, the standard injection rate pattern (one-dot chain line) shown in FIG. 9A is a broken line parallel to the injection rate change line from fully open to fully closed as shown in FIG. The fuel injection amount when the injection is completed until the valve is fully opened (same as the break point injection amount Qfl) and the injection amount after the fully opening (Qbs−Qfl) are divided. In this state, the fuel injection amount error (dQ1, dQ2) from the actual injection rate pattern (solid line) indicated by hatching is calculated.

First, a transient period fuel injection rate compensation correction amount dQ1, which is an error in the fuel injection amount when the injection is completed until fully open, is calculated by Equation 5 (S120).
[Formula 5] dQ1 ← Qfl × Rh × Rh
In FIG. 9B, the fuel injection rate compensation correction amount dQ1 during the transition period is proportional to the square of “(rQs−rq) / rQs”, and therefore, “(rQs−rq) / rQs” 2 It is expressed by the following formula.

[Formula 6] dQ1 =
Qfl × {(rQs−rq) / rQs} × {(rQs−rq) / rQs}
Therefore, from the relationship between the equations 3 and 4, equation 6 is equivalent to the equation 5, and the transient period fuel injection rate compensation correction amount dQ1 can be calculated by a quadratic equation of the change fuel injection rate ratio Rh as in the equation 5. .

Next, a full-open period fuel injection rate compensation correction amount dQ2, which is an error in the fuel injection amount (Qbs−Qfl) for the part after the full opening, is calculated by Expression 7 (S122).
[Formula 7] dQ2 <-(Qbs−Qfl) × Rh
In FIG. 9B, the full-open period fuel injection rate compensation correction amount dQ2 is proportional to “(rQs−rq) / rQs”, and therefore is a linear expression of “(rQs−rq) / rQs” as shown in Equation 8. It is represented by

[Formula 8] dQ2 = (Qbs−Qfl) × (rQs−rq) / rQs
Therefore, from the relationship between the equations 3 and 4, equation 8 is equivalent to the equation 7, and the full-open period fuel injection rate compensation correction amount dQ2 can be calculated by a linear equation of the change fuel injection rate ratio Rh as in the equation 7.

  Next, the case where Qbs <Qfl (YES in S118) will be described. For example, this is the case of Qbs = QB in FIG. 5, and the basic fuel injection time Tbs = TB is obtained in step S104.

In this case, the transition period fuel injection rate compensation correction amount dQ1 is calculated as shown in Equation 9 (S124).
[Formula 9] dQ1 ← Qbs × Rh × Rh
In the case of Qbs <Qfl, when the same value as the break point injection amount Qfl is set as the basic fuel injection amount Qbs, the value of “Qfl × Rh × Rh” is expressed by the above equation 5 as the fuel injection rate during the transient period. The compensation correction amount is dQ1. In this case, it has been found that the transient period fuel injection rate compensation correction amount dQ1 is reduced in proportion to the basic fuel injection amount Qbs being smaller than the break point injection amount Qfl. Exists.

[Formula 10] Qbs / Qfl = dQ1 / (Qfl × Rh × Rh)
From Expression 10, the transient period fuel injection rate compensation correction amount dQ1 is expressed by Expression 11.
[Formula 11] dQ1 = (Qfl × Rh × Rh) × (Qbs / Qfl)
= Qbs x Rh x Rh
In this way, the transient period fuel injection rate compensation correction amount dQ1 can be calculated by the quadratic expression of the change fuel injection ratio Rh as shown in the above equation 9.

At this time, since the fully open period fuel injection rate compensation correction amount dQ2 does not exist, “0” is set to the fully open period fuel injection rate compensation correction amount dQ2 (S126).
Next, the estimated fuel injection rate rqi (mm 3 / μsec) at the fuel injection valve 28 to which fuel injection is performed this time is calculated from the fuel injection rate map Maprq set for the fuel injection valve 28 to which fuel injection is performed this time. It is calculated based on the fuel pressure Pf, the basic fuel injection amount Qbs, and the in-cylinder pressure Pic at the start of fuel injection (S128).

  For each fuel injection valve 28, fuel injection rate data is measured using the fuel pressure, the fuel injection amount, and the in-cylinder pressure as parameters when the fuel injection valve 28 is manufactured. When each fuel injection valve 28 is assembled to the diesel engine 2, it is read into the ECU 40 from a data tag attached to each fuel injection valve 28 and is mapped as a fuel injection rate map Maprq. Using the fuel injection rate map Maprq for each fuel injection valve 28, the estimated fuel injection rate rqi at the time of injection is calculated. Note that other maps provided for each fuel injection valve 28 are similarly created and read from the data tag or the like to the ECU 40.

Next, the fuel injection rate compensation correction time dTh (μsec) is calculated as shown in Expression 12 (S130).
[Formula 12] dTh ← (dQ1 + dQ2) / rqi
Next, the injection timing correction coefficient Ki for obtaining the valve opening timing compensation correction time dTt is calculated from the map Mapi shown in FIG. 10 using the fuel pressure Pf as a parameter (S132).

Next, the valve opening timing compensation correction time dTt is calculated by Equation 13 (S134).
[Formula 13] dTt <-Ki x (Pic-Ps)
The difference between the in-cylinder pressure Pic at the start of fuel injection, which is the actual in-cylinder pressure, and the standard in-cylinder pressure Ps (Pic−Ps) causes a shift in the opening timing of the fuel injection valve 28 (ΔTh in FIG. 9). The sensitivity of the degree of deviation varies depending on the fuel pressure Pf. Therefore, a map Mapki is prepared in advance by actual measurement, and is calculated by the above equation (13).

  Then, using equation 14, the basic fuel injection time Tbs is corrected by the fuel injection rate compensation correction time dTh and valve opening timing compensation correction time dTt calculated as described above, and the invalid injection time dTx, and the fuel to be injected this time. An injection time (energization time) Tau for the injection valve 28 is calculated (S136).

[Formula 14] Tau <-Tbs + dTh + dTt + dTx
Then, at the fuel injection timing θi, a setting is made in the ECU 40 so that the energization for the injection time Tau is performed (S138), and this process is temporarily ended.

  In the configuration described above, the relationship with the claims is that steps S132 and S134 of the fuel injection control process (FIGS. 3 and 4) are processing as valve opening timing compensation correction time calculating means, and steps S118 to S126 are correction amount calculating means. It corresponds to the processing as. Further, steps S128 and S130 correspond to processing as fuel injection rate compensation correction time calculation means, steps S102 and S104 correspond to processing as fuel injection time calculation means, and step S136 corresponds to processing as fuel injection time correction means.

According to the first embodiment described above, the following effects can be obtained.
(I). In steps S118 to S126 of the fuel injection control process (FIGS. 3 and 4), the fuel injection valve 28 is divided into an on-off valve drive transient period and a full-open period according to the difference in the contribution of the fuel injection rate in the fuel injection process. The fuel injection rate compensation correction amount is calculated. That is, the transition period fuel injection rate compensation correction amount dQ1 is calculated for the on-off valve drive transition period (S120, S124), and the fully open period fuel injection rate compensation correction amount dQ2 is calculated for the fully open period (S122, S126). .

For this reason, the fuel injection amount can be appropriately corrected based on the difference between the pressure factors (in-cylinder pressure and fuel pressure), and the control accuracy of the fuel injection amount can be improved.
The transient period fuel injection rate compensation correction amount dQ1 and the fully open period fuel injection rate compensation correction amount dQ2 are not directly used for correcting the fuel injection amount, but based on the estimated fuel injection rate rqi (S128). Conversion to the compensation correction time dTh (S130), and correction for the basic fuel injection time Tbs is executed (S136). For this reason, it is possible to set an accurate fuel injection time Tau that matches the required fuel injection amount in accordance with the actual situation at the time of fuel injection.

  Further, the valve opening timing compensation correction time dTt for compensating for the fuel injection amount error in accordance with the change in the valve opening timing of the fuel injection valve 28 caused based on the pressure factor is expressed as the injection timing correction coefficient Ki and (Pic-Ps). It is calculated by the product (S132, S134). Then, the correction based on the valve opening timing compensation correction time dTt is performed together with the fuel injection rate compensation correction time dTh described above (S136).

  The opening timing of the fuel injection valve 28 changes due to a change in the pressure factor. Accordingly, by correcting the fuel injection time in consideration of the valve opening timing compensation correction time dTt, it becomes possible to more appropriately correct the fuel injection amount based on the difference in pressure factor, and Control accuracy will be improved.

Thus, in the direct injection internal combustion engine, highly accurate fuel injection control can be realized in consideration of the difference in contribution of the fuel injection rate.
(B). The estimated fuel injection rate rqi is calculated from the fuel injection rate map Maprq based on the fuel pressure Pf, the basic fuel injection amount Qbs corresponding to the required fuel injection amount, and the fuel injection start cylinder pressure Pic. Since such a fuel injection rate map Maprq is provided for each fuel injection valve 28 in advance, the fuel injection rate compensation correction amount dQ1 and the fully-opened fuel injection rate compensation correction amount can be easily and accurately corresponding to the actual fuel injection situation. The period fuel injection rate compensation correction amount dQ2 can be converted into the fuel injection rate compensation correction time dTh. Therefore, in the direct injection internal combustion engine, more accurate fuel injection control can be realized in consideration of the difference in contribution of the fuel injection rate.

  (C). As described in steps S118 to S126, the transient period fuel injection rate compensation correction amount dQ1 is calculated based on the relationship between the change fuel injection rate ratio Rh and the quadratic equation, and the fully open period fuel injection rate compensation correction amount dQ2 varies. It can be calculated based on the relationship between the fuel injection rate ratio Rh and the linear expression. This makes it possible to easily calculate the entire fuel injection rate compensation correction amount (dQ1 + dQ2).

[Other embodiments]
(A). In the first embodiment, as shown in FIG. 2, the fuel injection valve 28 includes the control chamber 80. However, in the direct-acting type fuel injection valve in which the control chamber 80 does not exist, the fuel injection valve opening timing is shown. Since there is no deviation (ΔTh in FIG. 9), it is not necessary to calculate the valve opening timing compensation correction time dTt. Therefore, in this case, steps S132 and S134 of the fuel injection control process (FIGS. 3 and 4) are unnecessary. Therefore, the calculation of the injection time Tau in step S136 is as shown in Equation 15.

[Formula 15] Tau <-Tbs + dTh + dTx
In such fuel injection control by the fuel injection valve, the effects (a) to (c) of the first embodiment are produced except for the valve opening timing compensation correction portion.

  (B). In the first embodiment, when Qbs <Qfl, the transient period fuel injection rate compensation correction amount dQ1 is calculated by the above equation 9, but it may be calculated as follows as another method.

  That is, in the case of fuel injection performed in a state where the opening degree (lift amount) is small as in the case where the needle valve 64 shown in FIG. 2 does not reach full open (full lift), actual fuel injection when fuel injection is performed is performed. The fuel pressure in the sac chamber 72 that is the pressure does not reach the fuel pressure Pf (rail pressure). Therefore, the fuel pressure in the sac chamber 72 can be estimated to obtain the transient period fuel injection rate compensation correction amount dQ1.

  Here, the fuel pressure in the sac chamber 72 is determined based on the lift position of the needle valve 64 and the fuel pressure Pf. The lift position of the needle valve 64 is determined based on the lift speed and time. The lift speed of the needle valve 64 can be obtained from the characteristics of the orifice flow rate of the fuel discharged from the control chamber 80 through the outlet orifice 78a of the fuel discharge path 78, and can be regarded as substantially constant speed, that is, constant. Therefore, the fuel pressure in the sac chamber 72 can be expressed as a function of time.

  Then, based on the fuel pressure in the sac chamber 72 and the basic fuel injection amount Qbs obtained based on the time as described above, a map for obtaining the change amount of the fuel injection amount per unit in-cylinder pressure is experimentally obtained in advance. I ask for it. Then, based on the difference between the in-cylinder pressure Pic at the start of fuel injection and the standard in-cylinder pressure Ps, a change amount of the fuel injection amount, that is, an error is obtained from the map, and this deviation amount is calculated as a transient period fuel injection rate compensation correction amount. Set as dQ1.

(C). The in-cylinder pressure Pic at the start of fuel injection is obtained as an estimated value at the time of fuel injection. Alternatively, an in-cylinder pressure sensor may be provided to obtain an actually measured value.
(D). Each example described above has been described with a diesel engine, but the present invention can be applied to a gasoline engine as long as it is an in-cylinder injection type.

1 is a schematic configuration diagram of a vehicle diesel engine and an engine control device according to a first embodiment. FIG. 2 is a configuration explanatory diagram of a fuel injection valve according to the first embodiment. 3 is a flowchart of fuel injection control processing executed by the ECU according to the first embodiment. The flowchart of a fuel injection control process similarly. The structure explanatory drawing of fuel injection time conversion map Mapts of Embodiment 1. FIG. FIG. 3 is a configuration explanatory diagram of a volume ratio map Mapvr according to the first embodiment. FIG. 3 is a configuration explanatory diagram of a breakpoint map Mapqfl according to the first embodiment. FIG. 3 is an explanatory diagram of a change in fuel injection rate during fuel injection in the first embodiment. Explanatory drawing of the calculation method of the transition period fuel injection rate compensation correction amount dQ1 and the full-open period fuel injection rate compensation correction amount dQ2 in the first embodiment. FIG. 3 is a configuration explanatory diagram of a map Mapki according to the first embodiment.

Explanation of symbols

  2 ... diesel engine, 4 ... combustion chamber, 6 ... intake valve, 8 ... intake port, 10 ... intake manifold, 12 ... surge tank, 14 ... intake route, 16 ... EGR route, 18 ... throttle valve, 18a ... throttle opening Sensor 18b motor 20 intake temperature sensor 21 intake pressure sensor 22 exhaust valve 24 exhaust port 26 exhaust manifold 28 fuel injection valve 30 fuel supply pipe 32 common rail 34 DESCRIPTION OF SYMBOLS ... Fuel pump, 36 ... Fuel pressure sensor, 40 ... ECU, 42 ... Accelerator pedal, 44 ... Accelerator opening sensor, 46 ... Cooling water temperature sensor, 48 ... Crankshaft, 50 ... Engine speed sensor, 52 ... Cylinder discrimination sensor, 62 ... Main body of fuel injection valve, 64 ... Needle valve, 64a ... Main piston, 64b ... Sub piston, 66 ... Coil spring, 6 DESCRIPTION OF SYMBOLS ... Fuel injection hole, 70 ... Seat part, 72 ... Suck chamber, 74 ... 1st fuel supply path, 76 ... 2nd fuel supply path, 76a ... Inlet orifice, 78 ... Fuel discharge path, 78a ... Outlet orifice, 80 ... Control Chamber, 82 ... Fuel reservoir, 84 ... Exhaust pressure control valve, E ... Folding point, Fc ... Energizing force, Fm, Fs ... Driving force.

Claims (7)

A fuel injection control device for a direct injection internal combustion engine that performs fuel injection by compensating for a fuel injection amount error from a fuel injection valve into a cylinder generated based on a pressure factor in fuel injection,
The fuel injection rate compensation correction amount for compensating the fuel injection rate error according to the change in the fuel injection rate generated based on the pressure factor is determined according to the difference in contribution of the fuel injection rate to the fuel injection amount in the fuel injection process. Correction amount calculation means for calculating,
The fuel injection rate for calculating the fuel injection rate compensation correction time by converting the fuel injection rate compensation correction amount calculated by the correction amount calculating means into the fuel injection time based on the estimated fuel injection rate at the time of fuel injection. Compensation correction time calculating means;
Fuel injection time calculating means for calculating a fuel injection time corresponding to a required fuel injection amount based on an operating state of the direct injection internal combustion engine;
Fuel injection time correction means for correcting the fuel injection time calculated by the fuel injection time calculation means by a correction time including the fuel injection rate compensation correction time calculated by the fuel injection rate compensation correction time calculation means ; Prepared ,
The correction amount calculating means divides the on / off valve drive transient period and the fully open period of the fuel injection valve according to the difference in contribution of the fuel injection rate in the fuel injection process, and In accordance with a fuel injection rate compensation correction amount that compensates for a fuel injection amount error corresponding to a change in fuel injection rate that occurs based on a pressure factor, and a change in fuel injection rate that occurs based on the pressure factor in the fully open period The fuel injection rate compensation correction amount is calculated by calculating a fuel injection rate compensation correction amount for the fully open period that compensates for the fuel injection amount error.
A fuel injection control apparatus for a direct injection internal combustion engine. A fuel injection control device for a direct injection internal combustion engine that performs fuel injection by compensating for a fuel injection amount error from a fuel injection valve into a cylinder generated based on a pressure factor in fuel injection,
A valve opening timing compensation correction time calculating means for calculating a valve opening timing compensation correction time for compensating for a fuel injection amount error in accordance with a change in the valve opening timing of the fuel injection valve caused based on the pressure factor;
The fuel injection rate compensation correction amount for compensating the fuel injection rate error according to the change in the fuel injection rate generated based on the pressure factor is determined according to the difference in contribution of the fuel injection rate to the fuel injection amount in the fuel injection process. Correction amount calculation means for calculating,
The fuel injection rate for calculating the fuel injection rate compensation correction time by converting the fuel injection rate compensation correction amount calculated by the correction amount calculating means into the fuel injection time based on the estimated fuel injection rate at the time of fuel injection. Compensation correction time calculating means;
Fuel injection time calculating means for calculating a fuel injection time corresponding to a required fuel injection amount based on an operating state of the direct injection internal combustion engine;
The fuel is obtained by a correction time including a valve opening timing compensation correction time calculated by the valve opening timing compensation correction time calculation means and a fuel injection rate compensation correction time calculated by the fuel injection rate compensation correction time calculation means. and a fuel injection time correction means for correcting the fuel injection time calculated by the injection time calculating means,
The correction amount calculating means divides the on / off valve drive transient period and the fully open period of the fuel injection valve according to the difference in contribution of the fuel injection rate in the fuel injection process, and In accordance with a fuel injection rate compensation correction amount that compensates for a fuel injection amount error corresponding to a change in fuel injection rate that occurs based on a pressure factor, and a change in fuel injection rate that occurs based on the pressure factor in the fully open period The fuel injection rate compensation correction amount is calculated by calculating a fuel injection rate compensation correction amount for the fully open period that compensates for the fuel injection amount error.
A fuel injection control apparatus for a direct injection internal combustion engine. 3. The estimated fuel injection rate according to claim 1, wherein the estimated fuel injection rate is calculated in advance from a map having in-cylinder pressure, fuel pressure, and the required fuel injection amount as parameters. A fuel injection control device for a direct injection type internal combustion engine, characterized in that the fuel injection amount is calculated based on a fuel injection amount. 4. The fuel injection control device for a direct injection internal combustion engine according to claim 1, wherein the pressure factors are in-cylinder pressure and fuel pressure. 3. The pressure factor is an in-cylinder pressure and a fuel pressure, and the valve opening timing compensation correction time calculating means calculates the valve opening timing compensation correction time from an actual in-cylinder pressure and a standard at the time of fuel injection. A fuel injection control device for a direct injection internal combustion engine, characterized in that the calculation is based on a product of a difference between the in-cylinder pressure and an injection timing correction coefficient obtained based on an actual fuel pressure value. 6. The pressure factor according to claim 1, wherein the pressure factor is an in-cylinder pressure and a fuel pressure, and the correction amount calculation means includes a pressure difference between an actual fuel pressure and an actual in-cylinder pressure at the time of fuel injection. Based on the ratio of the difference between the actual fuel pressure and the standard in-cylinder pressure, the change fuel injection represents the ratio between the standard fuel injection rate and the difference between the standard fuel injection rate and the actual fuel injection rate. And calculating the fully open period fuel injection rate compensation correction amount based on the relationship between the change fuel injection rate ratio and a linear expression, and calculating the transition period fuel injection rate compensation correction amount as the change fuel injection rate ratio. A fuel injection control device for a direct-injection internal combustion engine, which is calculated based on the relationship between and a quadratic equation. 7. The fuel injection control device for a direct injection internal combustion engine according to claim 3, wherein the actual in-cylinder pressure at the time of fuel injection is an estimated value or an actual measurement value at the time of fuel injection.

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