JP5589686B2 - Engine control device - Google Patents

Description

  The present invention relates to an engine control apparatus, and more particularly to an engine control apparatus that predicts the in-cylinder gas temperature of a compression ignition internal combustion engine that retards the closing timing of an intake valve.

  In the engine, the closing timing of the intake valve may be changed. Patent Document 1 discloses a diesel engine that controls the closing timing of an intake valve so that the gas temperature in the cylinder at the compression top dead center becomes a target temperature set according to the operating conditions of the engine. Further, the engine may predict the in-cylinder gas temperature. Patent Document 2 discloses a technique for calculating and correcting the in-cylinder gas temperature. In addition, Patent Document 3 discloses a valve operating device that changes valve timings of first and second engine valves that are the same kind of engine valves provided for one combustion chamber.

JP 2002-38911 A JP 2005-226655 A JP 2009-144521 A

  FIG. 14 is a diagram showing an effective compression ratio of the compression ignition type internal combustion engine according to the closing timing of the intake valve. FIG. 15 is a diagram showing a combustion history of a compression ignition type internal combustion engine. In FIG. 14, the vertical axis represents the effective compression ratio, and the horizontal axis represents the closing timing of the intake valve expressed by the crank angle after bottom dead center (ABDC). In FIG. 15, the vertical axis represents the in-cylinder local equivalent ratio, and the horizontal axis represents the in-cylinder local gas temperature.

  As shown in FIG. 14, in the compression ignition internal combustion engine, the effective compression ratio can be lowered by retarding the closing timing of the intake valve. Then, by reducing the in-cylinder gas temperature at the compression top dead center, for example, a combustion history as shown in FIG. 15 can be secured. As a result, deterioration of exhaust emissions such as NOx and smoke can be suppressed.

  However, when the intake valve is closed late, the following phenomenon occurs. FIG. 16 is a diagram showing a change in the intake flow rate when the intake valve is closed late. FIG. 17 is a view showing a change in the intake air temperature when the intake valve is closed late. In FIG. 16, the vertical axis represents the intake air flow rate, and the horizontal axis represents the crank angle. In FIG. 17, the vertical axis represents the intake air temperature, and the horizontal axis represents the crank angle. The horizontal axis is common between FIGS. 16 and 17. The crank angle from 360 ° to 540 ° is a process in which the piston descends corresponding to the intake stroke.

  As shown in FIG. 16, when the intake valve is closed late, hot gas flows backward from the cylinder to the intake port around 540 °. For this reason, as shown in FIG. 17, the intake air temperature increases around 540 °. Then, the backflowed gas is sucked into the cylinder in the next combustion cycle. As a result, the in-cylinder gas temperature at the start of compression increases.

  For this reason, if the in-cylinder gas temperature at the compression top dead center is predicted based on the in-cylinder gas temperature at the start of compression that does not particularly reflect the influence of the backflowing gas, the predicted temperature is between the predicted temperature and the actual temperature. Deviation occurs. Further, the exhaust emission may deteriorate against the prediction because the actual temperature is higher than the predicted temperature.

In order to obtain good combustion, it is necessary to consider not only the effective compression ratio but also volumetric efficiency. In this regard, when the flow coefficient of each intake port is different, the flow rate balance of each intake port sequentially changes depending on the engine speed and the phase difference of the valve timing between each intake valve. A change in the flow rate balance may affect the reverse flow rate of the gas.

  For this reason, if the reverse flow rate of the gas is not accurately grasped in consideration of the flow rate balance, a suitable effective compression ratio may not be obtained from the viewpoint of volume efficiency. In this regard, when viewed from the viewpoint of volumetric efficiency, if the reverse flow rate of the gas becomes excessive due to a decrease in the effective compression ratio, oxygen necessary for combustion may be insufficient in the next combustion cycle. That is, as a result of excessive reduction in volume efficiency, exhaust emission may be deteriorated.

  In view of the above problems, an object of the present invention is to provide an engine control device that can suitably predict the in-cylinder gas temperature at the start of compression when retarding the closing timing of the intake valve.

The present invention provides a first intake port that guides intake air to a combustion chamber, a second intake port having a flow coefficient smaller than that of the first intake port, and a first intake port that is provided for the first intake port. Among the intake valve and the second intake valve provided for the second intake port, and among the first and second intake valves, the closing timing of the second intake valve, or the closing timing and Provided for a compression ignition type internal combustion engine provided with a valve gear capable of changing a valve lift amount and a supercharger for supercharging intake air into the combustion chamber, and closing timing of the second intake valve The control means for retarding the angle and the back flow rate of the gas flowing back to the first intake port and the second intake port based on the flow rate balance of the first and second intake ports are corrected and corrected. Based on the reverse flow rate, the first intake port and the second intake port Increase in the cylinder interior gas temperature at the start of compression by backflow gas to the intake port, by correcting the temperature of the intake, the engine having a prediction means for predicting the in-cylinder gas temperature at the compression start It is a control device.

  According to the present invention, when the valve closing timing of the intake valve is retarded, the in-cylinder gas temperature at the start of compression can be suitably predicted.

1 is an overall configuration diagram of an engine and the like according to Embodiment 1. FIG. 1 is a schematic configuration diagram of an engine according to Embodiment 1. FIG. FIG. 3 is a valve layout diagram of the engine of the first embodiment. It is a figure which shows the change of a valve timing. It is a figure which shows the change of a valve timing. It is a figure which shows typically the map data of the reverse flow volume of gas. It is a figure which shows operation | movement of ECU of Example 1 with a flowchart. It is a figure which shows the mode of the change of the reverse flow volume according to retard amount, a compression ratio, intake air temperature, and in-cylinder gas temperature. It is a figure which shows valve arrangement | positioning of the engine of Example 2. FIG. It is a figure which shows the change of a valve timing. It is a figure which shows the flow volume balance of a partial intake port. It is a figure which shows operation | movement of ECU of Example 2 with a flowchart. It is a figure which shows operation | movement of ECU of Example 2 with a flowchart. It is a figure which shows the effective compression ratio according to the intake valve closing timing. It is a figure which shows the combustion log | history of a compression ignition type internal combustion engine. It is a figure which shows the change of the intake flow rate at the time of intake valve late closing. It is a figure which shows the change of the intake temperature at the time of intake valve late closing.

  Embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is an overall configuration diagram of the engine 50A and related components. FIG. 2 is a schematic configuration diagram of the engine 50A. FIG. 3 is a valve layout diagram of the engine 50A. As shown in FIG. 1, the intake system 10 includes an air flow meter 11, an intercooler 12, and an intake manifold 13. The air flow meter 11 measures the amount of intake air. The intercooler 12 cools the intake air compressed by the supercharger 30. Intake manifold 13 distributes intake air to each cylinder 51a of engine 50A.

  The exhaust system 20 includes an exhaust manifold 21 and a catalyst 22. The exhaust manifold 21 merges exhaust from each cylinder 51a into one exhaust passage on the downstream side. The catalyst 22 purifies the exhaust. The supercharger 30 includes a compressor unit 31 and a turbine unit 32. The supercharger 30 is an exhaust-driven variable displacement turbocharger, and is provided with a compressor unit 31 interposed in the intake system 10 and a turbine unit 32 interposed in the exhaust system 20.

  The engine 50A is a compression ignition type internal combustion engine (diesel engine). As shown in FIG. 2, the engine 50A includes a cylinder block 51, a cylinder head 52A, a piston 53, an intake valve 54A, an exhaust valve 55, a fuel injection valve 56, an intake side VVT (Variable Valve Timing) 57A, It has.

  A cylinder 51 a is formed in the cylinder block 51. A piston 53 is accommodated in the cylinder 51a. A cylinder head 52 </ b> A is fixed to the upper surface of the cylinder block 51. The combustion chamber 59 is formed as a space surrounded by the cylinder block 51, the cylinder head 52A, and the piston 53.

  An intake port 52aA and an exhaust port 52b are formed in the cylinder head 52A. The intake port 52aA guides intake air to the combustion chamber 59, and the exhaust port 52b exhausts gas from the combustion chamber 59. The cylinder head 52A is provided with an intake valve 54A and an exhaust valve 55. The intake valve 54A opens and closes the intake port 52aA, and the exhaust valve 55 opens and closes the exhaust port 52b.

  As shown in FIG. 3, the intake port 52aA specifically includes partial intake ports In1 and In2 branched and opened from the upstream side toward the combustion chamber 59. Further, the exhaust port 52b includes partial exhaust ports Ex1, Ex2 branched and opened from the downstream side toward the combustion chamber 59. The two intake valves 54A open and close the partial intake ports In1 and In2, and the two exhaust valves 55 open and close the partial exhaust ports Ex1 and Ex2. The partial intake ports In1 and In2 are provided so that the flow coefficients are equal to each other.

  As shown in FIG. 2, a fuel injection valve 56 is provided in the cylinder head 52A. The fuel injection valve 56 directly injects fuel into the cylinder. The cylinder head 52A is provided with an intake side VVT 57A. As the intake side VVT 57A, a valve closing timing of the intake valve 54A or a valve that can change the valve closing timing and the valve lift amount is applied. The intake side VVT 57A corresponds to a valve gear.

  As shown in FIG. 1, the engine 50 </ b> A includes a common rail 58. A fuel injection valve 56 is provided for each cylinder 51 a, and each fuel injection valve 56 is connected to a common rail 58. The common rail 58 accumulates fuel up to a predetermined pressure. The accumulated fuel is distributed to each fuel injection valve 56. Thereafter, when a drive current is applied to the fuel injection valve 56, the fuel injection valve 56 opens. As a result, fuel is injected from the fuel injection valve 56 into the cylinder. The fuel injected into the cylinder is self-ignited (compression ignition) at a cylinder temperature and cylinder pressure P0 suitable for ignition.

  Various sensors are provided in the engine 50A. Specifically, for example, the air flow meter 11, the crank angle sensor 71 for detecting the crank angle and the engine speed NE, the water temperature sensor 72 for detecting the cooling water temperature of the engine 50A, and the in-cylinder pressure P0 are detected. In-cylinder pressure sensor 73 is provided. Further, the intake system 10 is provided with a supercharging pressure sensor 74 for detecting the supercharging pressure P and a temperature sensor 75 for detecting the intake air temperature T0 ′. The intake side VVT 57A is provided with a valve timing sensor 76 for detecting the valve timing.

  The ECU 1A is an electronic control device and corresponds to an engine control device. The ECU 1A includes a microcomputer including a CPU, a ROM, a RAM, and an input / output circuit. Various sensors and switches such as the air flow meter 11 and the sensors 71 to 76 described above are electrically connected to the ECU 1A. Various control objects such as the supercharger 30, the fuel injection valve 56, the intake side VVT 57A, and the common rail 58 are electrically connected.

  The ROM is configured to store a program describing various processes executed by the CPU, map data, and the like. The ECU 1A functionally implements various control means, determination means, detection means, and the like by executing processing while using a temporary storage area of the RAM as required based on a program stored in the ROM. . For example, in the ECU 1A, the following control means and prediction means are functionally realized.

  The control means delays the valve closing timing of the intake valve 54A. Specifically, the intake side VVT 57A is controlled, and the valve closing timings of the two intake valves 54A are similarly retarded. More specifically, as shown in FIG. 4, the valve closing timings of the two intake valves 54A are similarly delayed by integrally changing the valve opening timings and the valve closing timings of the two intake valves 54A. Angle control. The retard angle control performed by the control means is retard angle control in the sense that the intake valve 54A is closed late. Therefore, the closing timing of the intake valve 54A is set to the retard side with respect to the intake bottom dead center.

  When the intake side VVT 57A can change the valve closing timing and the valve lift amount of the intake valve 54A, the control means fixes the valve opening timings of the two intake valves 54A as shown in FIG. Further, the valve closing timings of the two intake valves 54A may be similarly retarded by changing the valve lift amount.

  The predicting means predicts the in-cylinder gas temperature T0 at the start of compression in consideration of the flow rates of the partial intake ports In1 and In2. Specifically, the in-cylinder gas temperature is corrected by correcting the intake air temperature T0 ′ based on the differential pressure Pd between the in-cylinder pressure P0 and the supercharging pressure P, the retard amount α1 of the intake valve 54A, and the engine speed NE. Predict T0. The intake air temperature T0 ′ is specifically used as the in-cylinder gas temperature at the start of compression. For this reason, it is preferable that the intake air temperature T0 ′ is accurately estimated by further taking into account the transfer of heat of the intake air performed until the start of compression after being detected based on the output of the temperature sensor 75.

  The correction of the intake air temperature T0 ′ is performed based on the following correlation. FIG. 6 is a diagram schematically showing map data in which a reverse flow rate Fb of gas to the intake port 52aA is set. The vertical axis represents the engine speed NE, and the horizontal axis represents the differential pressure Pd. That is, in the map data shown in FIG. 6, the reverse flow rate Fb is set according to the differential pressure Pd and the engine speed NE. A line on the map data indicates an equivalence line. The map data shown in FIG. 6 is created on the assumption that the partial intake ports In1 and In2 have the same flow coefficient.

  The reverse flow rate Fb increases as the differential pressure Pd increases. Further, the higher the engine speed NE, the smaller. This is because the intake / exhaust time is shortened. As a result, the reverse flow rate Fb gradually increases from the upper left to the lower right of the map data. On the other hand, the retard amount α1 also affects the reverse flow rate Fb. On the other hand, the map data shown in FIG. 6 can be prepared for each predetermined retardation amount, for example, according to the retardation amount α1. For this reason, the reverse flow rate Fb can be modeled by the differential pressure Pd, the retard amount α1, and the engine speed NE.

  On the other hand, the increase in the in-cylinder gas temperature at the start of compression due to the backflowed gas corresponds to the backflow rate Fb. For this reason, it can model with the reverse flow Fb. Therefore, it can be modeled by the differential pressure Pd, the retard amount α1, and the engine speed NE. In contrast, the predicting means specifically corrects the intake air temperature T0 ′ by the amount of increase in the in-cylinder gas temperature at the start of compression due to the backflowed gas based on the reverse flow rate Fb. By correcting in this way, the intake air temperature T0 ′ is corrected based on the differential pressure Pd, the retard amount α1, and the engine speed NE.

The predicting means further predicts the in-cylinder gas temperature T at the compression top dead center based on the in-cylinder gas temperature T0. Specifically, the in-cylinder gas temperature T is further predicted based on the in-cylinder gas temperature T0, the compression ratio (effective compression ratio) ε, and the intake specific heat ratio κ by using the following equation (1). Equation (1) is a gas equation of state in polytropic change.
T = T0 × ε ^κ−1 (1)

  Next, the operation of the ECU 1A will be described using the flowchart shown in FIG. The ECU 1A determines whether or not it is in a stable state (step S1). In this step, it is determined whether or not a control start condition is satisfied, for example, whether or not an abnormality has occurred in the intake side VVT 57A. If a negative determination is made in step S1, this flowchart is temporarily terminated. If an affirmative determination is made in step S1, ECU 1A detects the closing timing (IVC) of intake valve 54A (step S2). Thereby, the compression ratio ε can be calculated.

  Subsequently, the ECU 1A detects the differential pressure Pd, the retard amount α1, and the engine speed NE (step S11A), and calculates the reverse flow rate Fb (step S12). As the differential pressure Pd, for example, a model that is modeled by a supercharging pressure P and a stroke volume may be used. Subsequent to step S12, the ECU 1A detects the intake air temperature T0 '(step S21), and predicts the in-cylinder gas temperature T0 based on the differential pressure Pd, the retard amount α1, and the engine speed NE (step S22).

  Thereafter, the ECU 1A calculates the in-cylinder gas temperature T using the above-described equation (1) (step S31). After step S31, this flowchart is terminated. In addition, the process from step S11A to S22 may be performed irrespective of whether it is a stable state in step S1.

  Next, the function and effect of the ECU 1A will be described. FIG. 8 is a diagram showing changes in the reverse flow rate Fb, the compression ratio ε, the in-cylinder gas temperature T0, and the in-cylinder gas temperature T according to the retardation amount α1. In FIG. 8, the vertical axis indicates the reverse flow rate Fb, the compression ratio ε, the in-cylinder gas temperature T0, and the in-cylinder gas temperature T, and the horizontal axis indicates the retardation amount α1 with a common scale. In FIG. 8, the in-cylinder gas temperature T ′ when predicted using the intake air temperature T0 ′ instead of the in-cylinder gas temperature T0 is also indicated by a broken line for reference.

  When the retardation amount α1 increases, the valve opening period becomes longer toward the compression stroke side. For this reason, the reverse flow rate Fb increases. Further, when the retardation amount α1 increases, the compression period becomes shorter. For this reason, the compression ratio ε decreases. As a result, the deterioration of exhaust emission can be suppressed by reducing the in-cylinder gas temperature T.

  On the other hand, when the retardation amount α1 increases, the in-cylinder gas temperature T0 also increases. This is because, for example, the reverse flow rate Fb is reflected in the in-cylinder gas temperature T0. As a result, the in-cylinder gas temperature T becomes higher than the in-cylinder gas temperature T ′. Thus, the ECU 1A predicts the in-cylinder gas temperature T0 reflecting the reverse flow rate Fb. As a result, when the valve closing timing of the intake valve 54A is retarded, the in-cylinder gas temperature at the start of compression can be suitably predicted. As a result, by predicting the in-cylinder gas temperature T based on the in-cylinder gas temperature T0, it is possible to prevent the exhaust emission from deteriorating against the prediction.

  In the present embodiment, the engine 50B is applied instead of the engine 50A, and the ECU 1B is applied instead of the ECU 1A, compared to the case of the first embodiment. Engine 50B includes intake side VVT 57B instead of intake side VVT 57A. Further, a cylinder head 52B is provided instead of the cylinder head 52A, and intake valves 54B and 54C are provided instead of the intake valve 54A. The engine 50B is substantially the same as the engine 50A except for these points. For this reason, illustration is abbreviate | omitted about the whole block diagram and the schematic block diagram of the engine 50B.

  Of the intake valves 54B and 54C, one that can change the valve closing timing of the intake valve 54C or the valve closing timing and the valve lift amount is applied to the intake side VVT 57B. Among the intake valves 54B and 54C, in order to change the closing timing of the intake valve 54C, one that can set the closing timing of the intake valves 54B and 54C independently of each other can be applied. As the intake side VVT 57B, for example, the valve gear disclosed in Patent Document 3 described above can be applied. The intake-side VVT 57B can be realized as a configuration having, for example, electromagnetic drive devices when the drive of the intake valves 54B and 54C is electromagnetically driven.

  FIG. 9 is a view showing a valve arrangement of the engine 50B. The cylinder head 52B is substantially the same as the cylinder head 52A except that an intake port 52aB is provided instead of the intake port 52aA. The intake port 52aB is substantially the same as the intake port 52aA except that partial intake ports In3 and In4 having different flow coefficients are provided instead of the partial intake ports In1 and In2. In this regard, the intake air flow rates of the intake ports 52aA and 52aB are equal to each other.

  The intake valve 54B is provided for the partial intake port In3, and the intake valve 54C is provided for the partial intake port In4. The partial intake port In4 has a smaller flow coefficient than the partial intake port In3. Specifically, the flow passage cross-sectional area of the partial intake port In4 is smaller than that of the partial intake port In3. For this reason, the intake valve 54C has a smaller valve diameter than the intake valve 54B. The partial intake port In3 corresponds to a first intake port, and the partial intake port In4 corresponds to a second intake port. The intake valve 54B corresponds to a first intake valve, and the intake valve 54C corresponds to a second intake valve.

  The ECU 1B is substantially the same as the ECU 1A except that the control means and the prediction means are realized as described below, and the first and second correction control means are further realized. For this reason, the illustration of the ECU 1B is omitted.

  The control means retards the closing timing of the intake valve 54C of the intake valves 54B and 54C instead of the intake valve 54A when performing the retard control. Specifically, as shown in FIG. 10, the valve closing timing of the intake valve 54C is changed by integrally changing the valve opening timing and the valve closing timing of the intake valve 54C while fixing the valve timing of the intake valve 54B. Delay angle control. For example, the control means may delay-control the closing timing of the intake valve 54C by changing the closing timing and the valve lift amount while fixing the opening timing of the intake valve 54C.

  The prediction means differs from the ECU 1A in that the intake air temperature T0 ′ is corrected based on the retard amount α2 of the intake valve 54C instead of the retard amount α1 of the intake valve 54A when correcting the intake temperature T0 ′. . Further, the prediction means further corrects the intake air temperature T0 ′ as described below in consideration of the flow rate balance of the partial intake ports In3 and In4.

  FIG. 11 is a diagram showing the flow rate balance of the partial intake ports In3 and In4 according to the engine speed NE and the retard amount α2. In the case of low rotation and no retardation shown in (a), the ratio of the flow rate of the partial intake port In3 is slightly larger than the partial intake port In4. On the other hand, in the case of the low rotation and the retard as shown in (b), the ratio of the flow rate flowing through the partial intake port In4 decreases. As a result, the reverse flow rate Fb also decreases as compared to the case where the flow rate coefficients of the partial intake ports In3 and In4 are the same.

  In the case of high rotation and no retardation shown in (c), the ratio of the flow rate flowing through the partial intake port In4 is reduced as compared with the case of (a). In the case of high rotation and delay angle shown in (d), the ratio of the flow rate flowing through the partial intake port In4 is reduced as compared with the case of (c). Moreover, it decreases even compared with the cases of (a) and (b). From these, it can be seen that the ratio of the flow rate flowing through the partial intake port In4 changes according to the engine speed NE and the retard amount α2. Further, it can be seen that the higher the engine speed NE and the greater the retard amount α2, the more it decreases.

  Therefore, the predicting means further corrects the intake air temperature T0 ′ based on the engine speed NE and the retard amount α2. Specifically, as the engine speed NE is higher, the reverse flow rate Fb, which is a correction value for the intake air temperature T0 ′, is decreased at a larger rate. The reverse flow rate Fb is decreased at a larger rate as the retardation amount α2 is larger. Thus, the intake air temperature T0 ′ is further corrected based on the flow rate balance of the partial intake ports In3 and In4.

When the in-cylinder gas temperature T is higher than the target gas temperature T _target , the first correction control means delays the valve closing timing of the intake valve 54C that is the target of the retard angle control. Further, the first correction control means advances the valve closing timing of the intake valve 54C to be retarded when the in-cylinder gas temperature T is lower than the target gas temperature T _target . For example, from the viewpoint of improving exhaust emission, a temperature determined in advance according to the operating condition of the engine 50B can be applied to the target gas temperature T _target .

If the in-cylinder gas temperature T does not decrease to the target gas temperature T _target even if the first correction control unit performs the retard control, the second correction control unit determines the delay of the fuel injection timing and the pilot injection amount. At least one of reduction, increase in common rail pressure, and decrease in supercharging pressure P is executed. In addition, the second correction control means, when the in-cylinder gas temperature T does not reach the target gas temperature T _target even if the first correction control means performs the advance angle control, the advance angle of the fuel injection timing, the pilot injection At least one of the increase in the amount and the increase in the supercharging pressure P is executed.

  Next, the operation of the ECU 1B will be described using the flowcharts shown in FIGS. The flowchart shown in FIG. 13 is a flowchart following the flowchart shown in FIG. The flowchart shown in FIG. 12 is the same as the flowchart shown in FIG. 7 except that step S11B is provided instead of step S11A and steps S15 and S16 are added. For this reason, these steps will be described with particular reference to FIG.

  As shown in FIG. 12, the ECU 1B detects the retard amount α2 instead of the retard amount α1 in step S11B, and calculates the reverse flow rate Fb in step S12. At this time, the ECU 1B calculates the reverse flow rate Fb based on the map data of the reverse flow rate Fb set in advance according to the differential pressure Pd, the retard amount α2, and the engine speed NE. The map data does not reflect the flow rate balance as in the first embodiment. Subsequent to step S12, the ECU 1B calculates the flow rate balance of the partial intake ports In3 and In4 based on the engine speed NE and the retard amount α2 (step S15).

  Subsequently, the ECU 1B corrects the reverse flow rate Fb based on the flow rate balance of the partial intake ports In3 and In4 (step S16). At this time, as the engine speed NE is higher and the retard amount α2 is larger, the reverse flow rate Fb is corrected to be smaller at a larger rate. Thereby, the in-cylinder gas temperature T0 further corrected based on the flow rate balance can be calculated in step S22. The influence of the flow rate balance may be reflected in advance on the map data of the reverse flow rate Fb.

As shown in FIG. 13, after step S31, the ECU 1B determines whether or not the in-cylinder gas temperature T is higher than the target gas temperature T _target (step S41). If the determination is affirmative, the ECU 1B determines whether correction is possible by changing the valve closing timing of the intake valve 54C (step S42). If the determination is affirmative, the ECU 1B controls to retard the closing timing of the intake valve 54C (step S43). On the other hand, if a negative determination is made in step S42, the ECU 1B performs adaptive correction by changing the fuel injection or the supercharging pressure P (step S44). Specifically, at least one of the retardation of the fuel injection timing, the decrease of the pilot injection amount, the increase of the common rail pressure, and the decrease of the supercharging pressure P is executed.

If a negative determination is made in step S41, the ECU 1B determines whether or not the in-cylinder gas temperature T is lower than the target gas temperature T _target (step S51). If the determination is negative, this flowchart ends. On the other hand, if an affirmative determination is made in step S51, the ECU 1B determines whether or not correction is possible by changing the valve closing timing of the intake valve 54C (step S52). If the determination is affirmative, the ECU 1B controls the advance of the closing timing of the intake valve 54C (step S53). On the other hand, if a negative determination is made in step S53, the ECU 1B performs adaptive correction by changing the fuel injection or the supercharging pressure P (step S54). Specifically, at least one of the advance of the fuel injection timing, the increase of the pilot injection amount, and the increase of the supercharging pressure P is executed.

  Next, the function and effect of the ECU 1B will be described. The ECU 1B further corrects the intake air temperature T0 ′ based on the engine speed NE and the retard amount α2 in consideration of the flow rate balance of the partial intake ports In3 and In4. As a result, the influence of the flow rate balance of the partial intake ports In3 and In4, which changes according to the engine speed NE and the retardation amount α2, on the prediction can also be corrected. Therefore, the in-cylinder gas temperature T0 can be predicted more suitably.

  Specifically, the ECU 1B decreases the reverse flow rate Fb at a larger rate as the engine speed NE is higher and as the retard amount α2 is larger. Thus, the in-cylinder gas temperature T0 can be appropriately predicted by correcting the reverse flow rate Fb according to the ratio of the flow rate flowing through the partial intake port In4.

Further, the ECU 1B delays the closing timing of the intake valve 54C when the in-cylinder gas temperature T is higher than the target gas temperature T _target . Thereby, the in-cylinder gas temperature T can be lowered. In addition, if the in-cylinder gas temperature T does not decrease to the target gas temperature T _target even with the retard control, the delay of the fuel injection timing, the decrease of the pilot injection amount, the increase of the common rail pressure, and the decrease of the supercharging pressure P are performed. At least one of them is executed. Thereby, the in-cylinder gas temperature T can be lowered. As a result, deterioration of NOx and smoke can be suppressed.

Further, when the in-cylinder gas temperature T is lower than the target gas temperature T _target , the ECU 1B controls the advance of the closing timing of the intake valve 54C. Thereby, the in-cylinder gas temperature T can be raised. In addition, if the in-cylinder gas temperature T does not reach the target gas temperature T _target even with the advance angle control, at least one of the advance angle of the fuel injection timing, the increase of the pilot injection amount, and the increase of the supercharging pressure P is required. Run one. Thereby, the in-cylinder gas temperature T can be raised. As a result, misfire and deterioration of THL (Total Hydro Carbon) can be suppressed.

  Although the embodiments of the present invention have been described in detail above, the present invention is not limited to such specific embodiments, and various modifications and changes can be made within the scope of the gist of the present invention described in the claims. It can be changed.

ECU 1A, 1B
Supercharger 30
Engine 50A, 50B
Intake port 52aA, 52aB
Intake valve 54A, 54B, 54C
Fuel injection valve 56
Intake side VVT 57A, 57B
Common rail 58
Combustion chamber 59

Claims (1)

A first intake port that guides intake air to the combustion chamber; a second intake port having a flow coefficient smaller than that of the first intake port; and a first intake valve provided for the first intake port; And the second intake valve provided for the second intake port and the closing timing of the second intake valve among the first and second intake valves, or the closing timing and the valve lift amount Is provided for a compression ignition type internal combustion engine provided with a valve operating device capable of changing the pressure and a supercharger for supercharging intake air to the combustion chamber,
Control means for retarding the closing timing of the second intake valve;
Based on the flow rate balance of the first and second intake ports, the reverse flow rate of the gas flowing back to the first intake port and the second intake port is corrected, and the first flow rate is corrected based on the corrected reverse flow rate. increase in the intake port and the second cylinder gas temperature at the start of compression by backflow gas to the intake port, by correcting the temperature of the intake, the prediction for predicting the in-cylinder gas temperature at the compression start And an engine control device.

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