JP4479469B2 - Internal combustion engine with a supercharger - Google Patents

Description

  The present invention relates to a supercharged internal combustion engine.

  In the internal combustion engine with a supercharger, a waste passage valve that opens and closes the communication passage that connects the upstream side and the downstream side with respect to the exhaust turbine of the supercharger is provided so that the engine output does not increase excessively, When the supercharging pressure rises, the waste gate valve is opened to reduce the flow rate of the exhaust gas passing through the exhaust turbine so that the supercharging pressure does not rise excessively.

  In addition, even when the amount of exhaust is small, such as in the low-rotation operation region of an internal combustion engine, a variable capacity that can increase the exhaust gas flow rate and increase the rotational speed and torque of the exhaust turbine by rotating the nozzle vane in the closing direction. A type turbocharger has been developed. By adjusting the amount of rotation of the nozzle vane, the rotational speed and rotational force of the compressor wheel can be increased, the intake air density can be increased, and the charging efficiency of the combustion chamber can be improved.

  By the way, in the supercharger-equipped internal combustion engine, the wastegate valve or nozzle vane is closed during acceleration even in an operation region where the wastegate valve or nozzle vane is opened during normal operation. By closing these wastegate valves or nozzle vanes, the amount of exhaust gas supplied to the exhaust turbine is increased, the number of revolutions of the exhaust turbine is increased, and the boost pressure rises quickly, improving the acceleration performance of the vehicle. can do.

  Further, an internal combustion engine having a variable valve mechanism that changes the opening / closing valve timings of the intake / exhaust valves in accordance with the operating state of the internal combustion engine (for example, intake air amount or supercharging pressure) has been developed. In a supercharger-equipped internal combustion engine equipped with this variable valve mechanism, during normal operation, for example, an operation region when the target supercharging pressure is relatively low (hereinafter referred to as a low supercharging pressure region) and a target supercharging. It is divided into two regions, an operation region when the pressure is relatively high (hereinafter referred to as a high boost pressure region), and the opening / closing valve timing of the intake / exhaust valve is adjusted according to a map set in advance in each region.

Here, at the time of waste gate valve opening control, the amount of overlap with the exhaust valve is increased by advancing the opening / closing timing of the intake valve than during normal boost pressure control, thereby improving engine torque in the low speed range. A technique for achieving this is known (for example, see Patent Document 1).
JP 2003-343273 A Japanese Patent Publication No. 6-74747 JP-A-9-125994 JP 2000-329871 A JP-A-3-233134 Japanese Patent Laid-Open No. 11-36906 JP-A-2-207138 Japanese Utility Model Publication No. 3-18665 JP-A-8-61074

However, at the time of acceleration, if the supercharging pressure and the intake / exhaust valve opening / closing timing are not in an appropriate relationship, the internal EGR amount increases due to an increase in the exhaust pressure upstream of the exhaust turbine, and the in-cylinder temperature The occurrence of knocking due to the rise in temperature, overheating due to the rise in exhaust temperature, overshooting of the supercharging pressure, etc. can occur. As a result, the increase in the supercharging pressure during acceleration transition may become slow, or drivability may deteriorate, making it difficult to quickly increase the supercharging pressure.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a technique capable of quickly increasing the supercharging pressure in an internal combustion engine with a supercharger.

In order to achieve the above object, the supercharged internal combustion engine according to the present invention employs the following means. That is,
A supercharging pressure variable mechanism capable of changing the rotation speed of the exhaust turbine of the supercharger;
A variable valve mechanism capable of changing a valve opening characteristic of at least one of an intake valve or an exhaust valve of an internal combustion engine;
With
During normal operation of the internal combustion engine, the variable supercharging pressure mechanism is operated at a low supercharging pressure region operated at a relatively low supercharging pressure and at a supercharging pressure higher than the low supercharging pressure region. The variable valve mechanism operates in accordance with each of the supercharging pressure regions of the high supercharging pressure region, and the variable valve mechanism has a valve opening characteristic corresponding to each of the low supercharging pressure region and the high supercharging pressure region. In the internal combustion engine with a supercharger provided,
During acceleration operation of the internal combustion engine, the supercharging pressure changing mechanism operates corresponding to a high supercharging pressure region, and the variable valve mechanism operates in a low supercharging pressure region until the supercharging pressure reaches a predetermined supercharging pressure. The valve opening characteristic corresponds to the above-mentioned, and when the supercharging pressure becomes higher than the predetermined supercharging pressure, the valve opening characteristic corresponds to the high supercharging pressure region.

  Here, the supercharging pressure variable mechanism adjusts the supercharging pressure by adjusting the amount of exhaust gas supplied to the exhaust turbine per unit time or the speed of the exhaust gas supplied to the exhaust turbine. During steady operation, an operation region that requires a relatively low boost pressure (hereinafter also referred to as a low boost pressure region) and an operation region that requires a relatively high boost pressure (hereinafter referred to as a high boost pressure). This is also referred to as a supercharging pressure region). The low boost pressure region is, for example, an operation region in which the engine generated torque at a predetermined rotational speed is less than or equal to a predetermined torque during steady operation. The high boost pressure region is, for example, at a predetermined rotational speed during steady operation. This is an operating region where the engine generated torque is larger than the predetermined torque.

  That is, in the low supercharging region, the amount of exhaust gas supplied to the exhaust turbine may be relatively small, or the exhaust speed may be relatively slow. Adjustment is performed so that the amount of exhaust gas decreases or the exhaust speed decreases. On the other hand, in the high supercharging region, the amount of exhaust supplied to the exhaust turbine must be relatively large, or the exhaust speed must be relatively fast. Adjustment is performed so that the amount of exhaust gas supplied to the exhaust gas increases or the exhaust speed increases. The high boost pressure region is an operation region where the amount of torque required for the internal combustion engine is relatively large. In addition, during acceleration operation, even if the current operating range is the low boost pressure range, the boost pressure variable mechanism increases the rotation speed of the exhaust turbine by setting it to correspond to the high boost pressure. Thus, the boost pressure can be quickly increased.

  Further, the variable valve mechanism adjusts the opening timing, closing timing, lift amount, and operating angle of at least one of the intake and exhaust valves to adjust the amount of fresh air and EGR that are sucked into the cylinder of the internal combustion engine. Then, the residual gas amount (internal EGR amount), pump loss, etc. are adjusted to change the operating state of the internal combustion engine. This variable valve mechanism is set differently in each of the low boost pressure region and the high boost pressure region during steady operation.

In the present invention, when the actual supercharging pressure is lower than the predetermined supercharging pressure during the acceleration operation, the variable valve operating mechanism is used even if the supercharging pressure changing mechanism is set to correspond to the high supercharging pressure region. In the mechanism, the setting corresponding to the low supercharging pressure region is maintained. On the other hand, when the pressure exceeds a predetermined boost pressure, the variable valve mechanism is set to correspond to the high boost pressure even in the low boost pressure region. Since the possibility of knocking is low in the low boost pressure region, the internal EGR amount can be increased and the exhaust temperature can be raised. Therefore, by setting the variable valve mechanism to a setting corresponding to the low supercharging pressure region until a predetermined supercharging pressure at which knocking is unlikely to occur, the internal EGR amount is increased and the boosting pressure is promoted. Therefore, drivability can be improved.

  On the other hand, the internal EGR amount can be reduced by setting the variable valve mechanism to the high boost pressure setting when the boost pressure variable mechanism is set to the high boost pressure setting during the transition. Thereby, generation | occurrence | production of the knock accompanying the raise of supercharging pressure can be suppressed. Therefore, when the actual supercharging pressure becomes higher than the predetermined supercharging pressure, the variable valve mechanism is set to a high supercharging pressure to suppress the occurrence of knocking.

  In this way, the variable valve mechanism is set to a low supercharging pressure until the actual supercharging pressure reaches the predetermined supercharging pressure, and after the actual supercharging pressure becomes higher than the predetermined supercharging pressure, the variable valve mechanism is set. By setting to a high supercharging pressure, it is possible to achieve both a rapid increase in supercharging pressure and suppression of knocking.

In order to achieve the above object, the supercharged internal combustion engine according to the present invention may employ the following means. That is,
A supercharging pressure variable mechanism capable of changing the rotational speed of the exhaust turbine of the supercharger according to the operating state of the internal combustion engine;
A variable valve mechanism capable of changing a valve opening characteristic of at least one of an intake valve or an exhaust valve of an internal combustion engine;
With
During steady operation of the internal combustion engine, the variable supercharging pressure mechanism is operated at a low supercharging pressure region operated at a relatively low supercharging pressure and at a supercharging pressure higher than the low supercharging pressure region. The variable valve mechanism operates in accordance with each of the supercharging pressure regions of the high supercharging pressure region, and the variable valve mechanism has a valve opening characteristic corresponding to each of the low supercharging pressure region and the high supercharging pressure region. In the internal combustion engine with a supercharger provided,
During acceleration operation of the internal combustion engine, the supercharging pressure changing mechanism operates in response to a high supercharging pressure region, and the variable valve mechanism allows the intake air to blow from the intake system to the exhaust system in the low supercharging pressure region. Further, the operating angle and / or overlap amount of at least one of the intake valve and the exhaust valve may be set.

  Here, the variable valve mechanism adjusts the operating angle and overlap amount of at least one of the intake / exhaust valves, thereby adjusting the amount of fresh air, EGR amount, and residual gas amount (internal gas) drawn into the cylinder of the internal combustion engine. EGR amount), pump loss, etc. are adjusted to change the operating state of the internal combustion engine. The variable valve mechanism is set differently in the low boost pressure region and the high boost pressure region during steady operation.

  In the present invention, during the acceleration operation, the supercharging pressure changing mechanism is set to correspond to the high supercharging pressure region, and the variable valve mechanism operates at least one of the intake valve and the exhaust valve so that the intake air is blown through. Set the angle and overlap amount.

  That is, the variable valve mechanism is such that when the amount of exhaust gas is increased by the boost pressure changing mechanism during acceleration operation, the air sucked into the cylinders of the internal combustion engine flows out (blows through) as it is into the exhaust system. The operating angle and overlap amount of at least one of the intake valve and the exhaust valve are increased.

As the intake air is blown through in this way, the amount of fresh air supplied into the cylinder increases, so that the combustion state in the cylinder is improved and the boost pressure can be quickly raised.
In the present invention, secondary fuel injection can be performed in the expansion stroke or exhaust stroke after the main fuel injection.

  Here, the fuel supplied into the cylinder by the secondary fuel injection is burned at the temperature of the combustion gas by the main injection. However, since the piston has already been pushed down by the main injection, the combustion gas by the sub-injection hardly discharges the piston and is discharged with a high temperature. Therefore, the energy supplied to the exhaust turbine is increased, and the supercharging pressure can be quickly increased. Thereby, drivability can be improved.

  In the internal combustion engine with a supercharger according to the present invention, the amount of exhaust gas supplied to the exhaust turbine is increased by setting the on / off valve timing of at least one of the exhaust valve or the intake valve to a low supercharging pressure during transition. The boost pressure can be quickly increased.

Hereinafter, a specific embodiment of an internal combustion engine with a supercharger according to the present invention will be described in Example 4 based on the drawings.

FIG. 1 is a diagram showing a schematic configuration of an internal combustion engine to which the supercharged internal combustion engine according to the present embodiment is applied, its intake / exhaust system, and a supercharger.
The internal combustion engine 1 shown in FIG. 1 is a water-cooled four-cycle diesel engine.

An intake pipe 2 and an exhaust pipe 3 are connected to the internal combustion engine 1.
A compressor housing 4 a of a turbocharger 4 that operates using exhaust energy as a drive source is provided in the middle of the intake pipe 2. An intake throttle valve 5 for adjusting the flow rate of intake air flowing through the intake pipe 2 is provided in the intake pipe 2 downstream of the compressor housing 4a. The intake throttle valve 5 is opened and closed by an electric actuator. A pressure sensor 14 for detecting the pressure in the intake pipe 2 is attached to the intake pipe 2 downstream of the intake throttle valve 5. An air flow meter 15 that outputs a signal corresponding to the flow rate of the intake air flowing through the intake pipe 2 is provided in the intake pipe 2 upstream of the compressor housing 4a. The air flow meter 15 measures the intake air amount of the internal combustion engine 1.

  On the other hand, a turbine housing 4 b of the turbocharger 4 is provided in the middle of the exhaust pipe 3. The turbine housing 4b is provided with an exhaust turbine 4c that is rotated by the energy of the exhaust.

  Further, a communication path 6 that connects the exhaust pipe 3 upstream of the turbine housing 4b and the exhaust pipe 3 downstream is provided. The communication passage 6 is provided with a waste gate valve 7 that adjusts the flow rate of the exhaust gas flowing through the communication passage 6. The wastegate valve 7 is connected to a diaphragm 8 that opens and closes the wastegate valve 7.

In this embodiment, a variable capacity turbocharger is used as the turbocharger 4.
FIG. 2 is a cross-sectional view showing the configuration of the variable capacity turbocharger. 2A shows the case where the nozzle vane 51 is open, and FIG. 2B shows the case where the nozzle vane 51 is closed.

  As shown in the drawing, the variable displacement turbocharger is configured to include a plurality of nozzle vanes 51 around the exhaust turbine 4c in the turbine housing 4b. The nozzle vane 51 is opened and closed by an actuator 52.

When the nozzle vane 51 is rotated to the closing side, the gap between the adjacent nozzle vanes 51 is narrowed, and the flow path between the nozzle vanes 51 is closed.
On the other hand, when the nozzle vane 51 is rotated to the opening side, the gap between the adjacent nozzle vanes 51 is widened, and the flow path between the nozzle vanes 51 is opened.

  In the variable displacement turbocharger configured as described above, the direction of the flow path between the nozzle vanes 51 and the gap between the nozzle vanes 51 are changed by adjusting the rotation direction and the rotation amount of the nozzle vanes 51 by the actuator 52. It becomes possible. That is, by controlling the rotation direction and the rotation amount of the nozzle vane 51, the direction, flow velocity, and amount of exhaust blown to the exhaust turbine 4c are adjusted.

  For example, when the amount of exhaust from the internal combustion engine 1 is small, by operating the actuator 52 to close the nozzle vane 51, the flow velocity of the exhaust blown to the exhaust turbine 4c increases, and the exhaust turbine 4c rotates even with a small amount of exhaust. The speed and rotational force can be increased. That is, when the amount of exhaust gas is small during acceleration operation, the supercharging pressure can be quickly increased by closing the nozzle vane 51.

  On the other hand, when the amount of exhaust from the internal combustion engine 1 is sufficiently large, by operating the actuator 52 to open the nozzle vane 51, the excessive increase in the flow velocity of the exhaust blown to the exhaust turbine 4c is controlled, and the exhaust turbine 4c. It is possible to suppress an excessive increase in rotational speed and rotational force. That is, when the supercharging pressure becomes high, an excessive increase in the supercharging pressure can be suppressed by opening the nozzle vane 51.

In this embodiment, the internal combustion engine 1 includes a variable valve mechanism.
Here, FIG. 3 and FIG. 4 are schematic configuration diagrams of the variable valve mechanism according to the present embodiment. 3 is a longitudinal sectional view, and FIG. 4 is a top view.

  In the internal combustion engine 1, the opening / closing operation of the intake valve 20 is performed by the intake side cam 21. The intake side cam 21 is attached to an intake side camshaft 22, and an intake side pulley 23 is provided at the end of the intake side camshaft 22. Further, a variable rotation phase mechanism (hereinafter referred to as “intake side VVT”) 24 that can change the relative rotation phase between the intake side camshaft 22 and the intake side pulley 23 is provided. The intake side VVT 24 controls the relative rotational phase of the intake side camshaft 22 and the intake side pulley 23 in accordance with a command from the ECU 10. Further, an intake side cam angle sensor 25 for detecting the rotation angle of the intake side camshaft 22 is provided, and the intake side cam angle sensor 25 and the ECU 10 are electrically connected.

  The exhaust valve 26 is opened and closed by an exhaust cam 27. The exhaust side cam 27 is attached to the exhaust side cam shaft 28, and an exhaust side pulley 29 is provided at the end of the exhaust side cam shaft 28. Further, a variable rotation phase mechanism (hereinafter referred to as “exhaust side VVT”) 30 that can change the relative rotation phase between the exhaust side camshaft 28 and the exhaust side pulley 29 is provided. The exhaust side VVT 30 controls the relative rotational phase of the exhaust side camshaft 28 and the exhaust side pulley 29 in accordance with a command from the ECU 10. Further, an exhaust side cam angle sensor 31 for detecting the rotation angle of the exhaust side camshaft 28 is provided, and the exhaust side cam angle sensor 31 and the ECU 10 are electrically connected.

The rotational drive of the intake side camshaft 22 and the exhaust side camshaft 28 is performed by the driving force of the crankshaft 32. Specifically, a timing belt 34 is hung on the crank pulley 33, the intake pulley 23, and the exhaust pulley 29 provided on the crankshaft 32.

  In this way, the intake side camshaft 22 and the exhaust side camshaft 28 are rotationally driven by the driving force of the crankshaft 32, so that the intake side cam 21 and the exhaust side cam 27 cause the intake valve 20 and the exhaust valve 26 to move. Opening and closing operations are performed.

  In the internal combustion engine 1, the relationship between the crank angle and the cam angles of the intake and exhaust valves 20 and 26 is based on signals from the crank position sensor 13, the intake side cam angle sensor 25, and the exhaust side cam angle sensor 31. The rotation phases of the intake side camshaft 22 and the exhaust side camshaft 28 are feedback-controlled by the intake side VVT 24 and the exhaust side VVT 30 so as to have an appropriate relationship.

  The internal combustion engine 1 configured as described above is provided with an ECU 10 that is an electronic control unit for controlling the internal combustion engine 1. The ECU 10 is a unit that controls the operation state of the internal combustion engine 1 in accordance with the operation conditions of the internal combustion engine 1 and the request of the driver.

  Further, the ECU 10 outputs an electric signal corresponding to the amount of depression of the accelerator pedal 11 by the driver, an accelerator opening sensor 12 that can detect the engine load state, and a crank position sensor 13 that detects the engine speed. Various sensors are connected via electric wiring, and output signals of these various sensors are input to the ECU 10.

On the other hand, the intake throttle valve 5 is connected to the ECU 10 via electric wiring, and the intake throttle valve 5 is controlled by the ECU 10.
Here, in the present embodiment, when the internal combustion engine 1 is in a steady operation state, that is, when the engine speed and the engine generated torque are substantially constant, the nozzle vane 51 is based on the engine speed and the engine generated torque. Is determined. Further, the amount by which the valve opening timing of the intake valve 20 is advanced with respect to the crank angle (hereinafter referred to as the amount of advance of the intake side VVT 24) and the amount by which the valve opening timing of the exhaust valve 26 is advanced with respect to the crank angle. (Hereinafter referred to as the advance amount of the exhaust side VVT 30) is determined based on the engine speed and the intake air amount of the internal combustion engine 1. Hereinafter, the advance amount of the intake side VVT 24 and the advance amount of the exhaust side VVT 30 are also collectively referred to as “VVT advance amount”.

  For example, FIG. 5 is a diagram showing the relationship between the engine speed, the engine generated torque, and the open / close state of the nozzle vane 51. The horizontal axis is the engine speed, and the vertical axis is the engine generated torque. When the engine generated torque is larger than the boundary line A, the nozzle vane 51 is closed, and when it is equal to or lower than the boundary line A, the nozzle vane 51 is opened. Hereinafter, an operation region where the engine generated torque is larger than the boundary line A is referred to as “VNT closed region”, and an operation region where the engine generated torque is equal to or less than the boundary line A is referred to as “VNT open region”. That is, in the VNT closed region, the nozzle vane 51 is closed to increase the engine generated torque, while in the VNT open region, the nozzle vane 51 is opened to decrease the engine generated torque.

  Here, the VNT closed region in the present embodiment is an operation region in which a high supercharging pressure is required, and corresponds to a high supercharging pressure region in the present invention. Further, the VNT open region in this embodiment is an operation region where only a low supercharging pressure is required, and corresponds to the low supercharging pressure region in the present invention.

  Next, FIG. 6 is a diagram showing the state of engine speed and engine generated torque during transient operation. When the operating state of the internal combustion engine 1 shifts from A0 to B0, the internal combustion engine 1 passes through the operating states of A0, A1, A2, B1, and B0 in order.

  Conventionally, when the internal combustion engine 1 is in a transient operating state, that is, when the engine speed or the engine generated torque changes, the operating state of the internal combustion engine 1 is set to the VNT open region in order to quickly increase the supercharging pressure. Even (between A0 and A1), the nozzle vane 51 was closed. As a result, the back pressure upstream of the exhaust turbine 4c increases. Here, FIG. 7 is a diagram showing the relationship between the opening degree of the nozzle vane 51 (VNT opening degree) and the back pressure. As described above, when the nozzle vane 51 is closed, the back pressure increases. However, as the back pressure increases, the intake air amount decreases and the internal EGR amount increases.

  On the other hand, since the advance amounts of the intake side VVT 24 and the exhaust side VVT 30 are determined based on the engine speed and the intake air amount, even if the intake air amount is changed by closing the nozzle vane 51, the actual engine The advance amount is determined based on the rotation speed and the intake air amount. Here, FIG. 8 is a diagram showing the relationship among the intake air amount, the VVT advance amount, and the engine speed of the internal combustion engine 1. The VVT advance amount here may be the overlap amount of the intake and exhaust valves.

  FIG. 9 is a diagram showing the relationship between the opening degree (VNT opening degree) of the nozzle vane 51 and the internal EGR amount. Thus, since the internal EGR amount increases as the opening degree of the nozzle vane 51 decreases, the internal EGR amount increases during transient operation even when the intake air amount is the same as during steady operation. For this reason, during transient operation, knocking, overheating due to an increase in exhaust temperature, and overshooting of supercharging pressure can occur.

  Here, FIG. 10 is a time chart showing the transition of the opening / closing state (VNT opening degree) of the nozzle vane 51, the actual intake air amount during the transient operation, and the intake air amount obtained on the map. The solid line in “VNT opening” indicates the open / close state of the nozzle vane 51 during acceleration operation, and the broken line indicates the open / close state of the nozzle vane 51 obtained from FIG. 6. In the transition of “intake air amount”, the actual intake air amount is indicated by a solid line, and the intake air amount obtained on the map is indicated by a broken line. Further, the actual intake air amount means that the supercharging pressure rises due to the rotation of the nozzle vane 51 toward the closing side in accordance with the acceleration between A0 and A1 in FIG. And the intake air amount obtained on the map indicates the intake air amount of the internal combustion engine 1 obtained in a steady state in the VNT open region. A hatched portion in FIG. 10 corresponds to an increase in internal EGR.

  Thus, the internal EGR amount becomes excessive in the VNT open region during acceleration operation, and knocking, overheating of exhaust system members due to an increase in exhaust temperature, overshoot of supercharging pressure, etc. can occur.

  On the other hand, FIG. 11 is a time chart showing the transition of the open / close state (VNT opening degree), the intake air amount, and the VVT advance amount of the nozzle vane 51 according to this embodiment. The solid line in “VNT opening” indicates the open / close state of the nozzle vane 51 during acceleration operation, and the broken line indicates the open / close state of the nozzle vane 51 obtained from FIG. 6. In “VVT advance amount”, the solid line indicates the case according to the present embodiment, and the broken line indicates the case according to the prior art. Here, conventionally, as shown in FIG. 8, when the intake air amount is relatively small, the VVT advance amount is increased together with the increase of the intake air amount, so that the intake air is between A0 and A1. As the amount increased, the VVT advance amount was increased.

On the other hand, in the present embodiment, during the transient operation, even if the operating state of the internal combustion engine 1 is in the VNT open region, the VVT advance amount corresponding to the opening degree of the nozzle vane 51 is used. In other words, the setting of the VVT advance amount during acceleration is the setting for the VVT closed region. The VVT advance amount at this time is a map in which a value set in the VVT closed region is obtained in advance through experiments or the like, and shows a relationship between the engine speed, the intake air amount, and the VVT advance amount. Is obtained by substituting the engine speed and the intake air amount into.

  Thus, by setting the advance amounts of the intake side VVT 24 and the exhaust side VVT 30 according to the opening degree of the nozzle vane 51, the internal EGR amount can be reduced and the occurrence of knocking can be suppressed.

Next, the flow of the advance amount control of the intake side VVT 24 and the exhaust side VVT 30 according to this embodiment will be described.
FIG. 12 is a flowchart of the VVT advance amount control according to this embodiment. This flow is executed every predetermined time.

  In step S101, the ECU 10 reads the engine speed and the accelerator opening. The engine speed is obtained based on the output signal of the crank position sensor 13, and the accelerator opening is obtained based on the output signal of the accelerator opening sensor 12.

  In step S102, the ECU 10 determines whether or not it is a supercharging pressure control operation region. The supercharging pressure control operation region refers to an operation region in which the nozzle vane 51 is closed during acceleration in order to quickly increase the supercharging pressure. Here, it is determined whether or not the accelerator opening is relatively small and the engine speed is relatively low. This supercharging pressure control operation region may be obtained and set in advance through experiments or the like as a region in which the supercharging pressure quickly rises by closing the nozzle vane 51.

If an affirmative determination is made in step S102, the process proceeds to step S103, whereas if a negative determination is made, the process proceeds to step S106.
In step S103, the ECU 10 determines whether or not the engine is in the VNT open region when the internal combustion engine 1 is in steady operation based on the engine speed and the accelerator opening read in step S101. That is, in the example of FIG. 6, it is determined whether or not it is between A0 and A1.

If an affirmative determination is made in step S103, the process proceeds to step S104. On the other hand, if a negative determination is made, the process proceeds to step S106.
In step S104, the ECU 10 calculates the opening degree of the nozzle vane 51. Since the opening degree of the nozzle vane 51 is controlled by the ECU 10, the ECU 10 calculates the opening degree of the nozzle vane 51 from the control history of the nozzle vane 51.

  In step S105, the ECU 10 performs VVT advance amount control during supercharging pressure control. The actual intake air amount is calculated from the output signal of the air flow meter 15, and the advance amounts of the intake side VVT 24 and the exhaust side VVT 30 according to the opening degree of the nozzle vane 51 are calculated. Specifically, the relationship between the actual intake air amount, the engine speed, the opening degree of the nozzle vane 51, and the advance amount of the VVT is obtained in advance through experiments or the like, and is mapped to this map. The VVT advance amount is obtained by substituting the rotation speed and the opening degree of the nozzle vane 51.

Further, since the combustion state in the cylinder also changes when the internal EGR amount changes, the optimal ignition timing is calculated. This ignition timing is obtained in advance through experiments and mapped.
In step S106, the ECU 10 performs VVT advance amount control during normal operation. The VVT advance amount during normal operation is a VVT advance amount obtained from a map of the relationship between the actual intake air amount and the engine speed. At this time, the VVT advance amount is determined regardless of the actual opening of the nozzle vane 51. Further, as in step S105, an optimal ignition timing is also calculated.

Thus, the VVT advance amount corresponding to the opening degree of the nozzle vane 51 can be set during acceleration operation.
As described above, according to the present embodiment, the internal EGR amount is excessive by setting the VVT advance amount corresponding to the VNT opening (closed opening) even in the VNT open region during acceleration operation. Can be suppressed. Thereby, a supercharging pressure can be raised rapidly and drivability can be made favorable. In addition, occurrence of knocking, overheating of exhaust system members, and the like can be suppressed.

  In the present embodiment, the example in which the supercharging pressure is adjusted by changing the opening of the nozzle vane 51 has been described. However, in the present embodiment and the following embodiments, the opening of the wastegate valve 7 is changed. Thus, the supercharging pressure may be adjusted.

In the present embodiment, unlike the first embodiment, the normal control VVT advance amount is set until a predetermined boost pressure is reached.
The other hardware is the same as that of the first embodiment, and a description thereof will be omitted.

  Here, FIG. 13 is a time chart showing the transition of the open / close state (VNT opening degree), the intake air amount, and the VVT advance amount of the nozzle vane 51 according to the present embodiment. The solid line in “VNT opening” indicates the open / close state of the nozzle vane 51 during acceleration operation, and the broken line indicates the open / close state of the nozzle vane 51 obtained from FIG. 6. In “VVT advance amount”, the solid line indicates the case according to the present embodiment, and the broken line indicates the case according to the prior art.

  In this embodiment, during transient operation, when the advance angle amount of the intake side VVT 24 and the exhaust side VVT 30 is assumed to be the normal advance amount, that is, if the steady operation is performed until the predetermined boost pressure is reached, the engine The advance amount is set based on the rotation speed and the intake air amount. When the actual supercharging pressure becomes higher than the predetermined supercharging pressure, the VVT advance amount is set in accordance with the opening degree of the nozzle vane 51 as in the first embodiment.

  In this way, first, the internal EGR increases until the predetermined boost pressure is reached, so the exhaust temperature rises and the energy supplied to the exhaust turbine 4c increases, so the boost pressure rises quickly. . However, since the supercharging pressure is still low, almost no knocking occurs. On the other hand, when the actual supercharging pressure becomes higher than the predetermined supercharging pressure, the internal EGR amount can be reduced by setting the VVT advance amount according to the opening degree of the nozzle vane 51, and knocking Can be suppressed. Here, the “predetermined boost pressure” can be the upper limit of the boost pressure at which knocking does not occur even when the VVT advance amount is a normal advance amount during transient operation. Find it by experiment.

Next, the flow of the advance amount control of the intake side VVT 24 and the exhaust side VVT 30 according to this embodiment will be described.
FIG. 14 is a flowchart of VVT advance amount control according to this embodiment. This flow is executed every predetermined time. In addition, about the step where the same process as the said flow is made, the same code | symbol is attached | subjected and description is abbreviate | omitted.

In step S201, the ECU 10 reads the actual supercharging pressure. The actual supercharging pressure is obtained from the output signal of the pressure sensor 14.
In step S202, the ECU 10 determines whether or not the actual boost pressure is smaller than a predetermined boost pressure. This predetermined supercharging pressure is a supercharging pressure at which knocking may occur during a transition, and is the same as described above.

If an affirmative determination is made in step S202, the process proceeds to step S203, whereas if a negative determination is made, the process proceeds to step S104.
In step S203, the ECU 10 performs VVT advance amount control during supercharging pressure control. In this step, unlike the VVT advance amount control described in step S105, the VVT advance amount when the steady operation is performed in the nozzle vane opening region is calculated. That is, the VVT advance amount during normal operation is calculated.

  Specifically, the relationship between the actual intake air amount, the engine speed, and the VVT advance amount in the nozzle vane open region is obtained in advance through experiments or the like, and is mapped to this map. Is substituted for VVT advance amount. Further, as in step S105, the optimal ignition timing is calculated.

  In this way, the normal VVT advance amount in the nozzle vane opening region is set until the predetermined supercharging pressure is reached during the transient operation, and after the predetermined supercharging pressure is reached, the opening degree of the nozzle vane 51 (that is, the nozzle vane 51 is set). Can be set to a VVT advance amount corresponding to the degree of opening when the is rotated to the closing side. Thereby, the increase of the supercharging pressure can be promoted by increasing the internal EGR amount until the predetermined supercharging pressure is reached, and the occurrence of knocking can be suppressed after reaching the predetermined supercharging pressure.

  As described above, according to this embodiment, the normal VVT advance amount is set until the predetermined boost pressure is reached during acceleration operation, and the VNT opening region is reached after the predetermined boost pressure is reached. Further, by setting the VVT advance amount corresponding to the VNT opening (closed opening), it is possible to suppress the internal EGR amount from becoming excessive. Thereby, a supercharging pressure can be raised rapidly and drivability can be made favorable. In addition, occurrence of knocking, overheating of exhaust system members, and the like can be suppressed.

  The present embodiment is different from the first embodiment in that a working angle variable mechanism capable of changing the working angles of the intake side camshaft 22 and the exhaust side camshaft 28 is provided. As the working angle variable mechanism, for example, a mechanism described in Japanese Patent Laid-Open No. 2001-263015 can be used.

The other hardware is the same as that of the first embodiment, and a description thereof will be omitted.
Here, in a conventional internal combustion engine provided with a variable working angle mechanism, the engine speed, the intake air amount of the internal combustion engine 1, and the working angles of the intake camshaft 22 and the exhaust camshaft 28 (hereinafter simply referred to as cams). The operating angle of the camshaft is obtained by substituting the engine speed and the intake air amount into a control map (see FIG. 15) showing the relationship between the operating angle of the shaft and the operating angle of the shaft. That is, the working angle of the camshaft is determined based on the engine speed and the intake air amount of the internal combustion engine 1. 6 is a low load state and the intake air amount is small, the working angle set in a state where the nozzle vane 51 is opened is applied.

However, during the acceleration operation, between A0 and A1, since the nozzle vane 51 is rotated to the closing side in order to increase the supercharging pressure, the back pressure increases.
Here, FIG. 16 is a diagram showing the relationship among the working angle of the camshaft, the intake air amount, and the engine speed. In “low rotation”, when the operating angle of the camshaft increases, the back pressure increases, and the internal EGR is blown back to the intake pipe 2. In the intake stroke, fresh air is sucked after the blown-back internal EGR is sucked into the cylinder, so the amount of intake air is reduced. If the working angle of the camshaft is the same as that when the nozzle vane 51 is opened between A0 and A1, the gas exchange in the cylinder is not performed well, and the amount of intake air is reduced. Acceleration slows down.

On the other hand, in this embodiment, the operating angle of the camshaft is set according to the opening degree of the nozzle vane 51 during acceleration operation.
Here, FIG. 17 is a time chart showing transition of the open / close state (VNT opening degree) of the nozzle vane 51 and the intake air amount at the time of transition. The solid line in “VNT opening” indicates the open / close state of the nozzle vane 51 during acceleration operation, and the broken line indicates the open / close state of the nozzle vane 51 obtained from FIG. 6. Further, the solid line in the “intake air amount” is based on this embodiment, and the broken line is based on the conventional internal combustion engine.

  During the transition, the nozzle vane 51 is rotated toward the closing side, and in this embodiment, the working angle of the camshaft is set according to the opening degree of the nozzle vane 51 at that time. Here, in the present embodiment, the relationship among the intake air amount, the opening degree of the nozzle vane 51, and the operating angle of the camshaft is obtained in advance through experiments or the like and mapped. By doing so, the intake air amount between A0 and A1 increases as shown in FIG.

Next, the flow of the camshaft operating angle control according to this embodiment will be described.
FIG. 18 is a flowchart of the camshaft operating angle control according to this embodiment. This flow is executed every predetermined time. In addition, about the step in which the same process as the said flow is made, the same code | symbol is attached | subjected and description is abbreviate | omitted.

  In step S301, the ECU 10 performs a working angle control of the camshaft during the supercharging pressure control. In this step, the actual intake air amount is calculated from the output signal of the air flow meter 15, and the working angle of the camshaft corresponding to the opening degree of the nozzle vane 51 is calculated. Specifically, the relationship between the actual intake air amount, the engine speed, the opening degree of the nozzle vane 51, and the camshaft operating angle is obtained in advance through experiments or the like, and is mapped to this map. The operating angle of the camshaft is obtained by substituting the rotational speed and the opening degree of the nozzle vane 51. Further, the VVT advance amount is also calculated in the same manner as in step S105. Further, the optimal ignition timing is calculated. This ignition timing is obtained in advance through experiments and mapped.

  In step S302, the ECU 10 performs camshaft operating angle control during normal operation. The camshaft operating angle control during normal operation is a camshaft operating angle obtained from a map of the relationship between the actual intake air amount and the engine speed. At this time, the working angle of the camshaft is determined regardless of the actual opening of the nozzle vane 51. Similarly to step S106, the VVT advance amount is also calculated. Furthermore, the optimal ignition timing is also calculated.

In this way, the operating angle of the camshaft can be set according to the opening degree of the nozzle vane 51 during transient operation.
As described above, according to the present embodiment, by setting the camshaft operating angle corresponding to the VNT opening (closed opening) even in the VNT open region during acceleration operation, The amount of intake air can be increased. Thereby, a supercharging pressure can be raised rapidly and drivability can be made favorable.

The present embodiment is different from the third embodiment in that the camshaft operating angle is increased until the intake air blows through the exhaust system in the VNT open region during acceleration operation.
The other hardware is the same as that of the first embodiment, and a description thereof will be omitted.

  In the present embodiment, the camshaft operating angle and the VVT advance amount are set so that the intake air blows through during acceleration, and after the main injection into the cylinder of the internal combustion engine 1 as described below. The secondary injection for injecting the fuel again during the expansion stroke or the exhaust stroke is also used.

  Here, FIG. 19 is a time chart showing the transition of the open / close state (VNT opening degree) of the nozzle vane 51 and the intake air amount during the transition. The solid line in “VNT opening” indicates the open / close state of the nozzle vane 51 during acceleration operation, and the broken line indicates the open / close state of the nozzle vane 51 obtained from FIG. 6. Further, the solid line in the “intake air amount” is based on this embodiment, and the broken line is based on the conventional internal combustion engine.

When the blow-in of the intake air occurs, the internal EGR blown back to the intake pipe 2 is almost flowed to the exhaust pipe 3, so that the amount of fresh air in the cylinder can be increased.
Further, by performing the sub-injection together, the energy supplied to the exhaust turbine is increased, the boost pressure is further increased, and the drivability is improved.

Next, the camshaft operating angle control flow when the camshaft operating angle and the VVT advance amount are set so that the intake air blows through and the sub-injection is used together will be described.
FIG. 20 is a flowchart of the camshaft operating angle control when the camshaft operating angle and the VVT advance angle are set so that the intake air is blown through and the sub-injection is used together. This flow is executed every predetermined time. In addition, about the step in which the same process as the said flow is made, the same code | symbol is attached | subjected and description is abbreviate | omitted.

  In step S401, the ECU 10 performs camshaft operating angle control during supercharging pressure control. In this step, the actual intake air amount is calculated from the output signal of the air flow meter 15, and the working angle of the camshaft corresponding to the opening degree of the nozzle vane 51 is calculated. Specifically, the relationship between the actual intake air amount, the engine speed, the opening degree of the nozzle vane 51, and the camshaft operating angle is obtained in advance through experiments or the like, and is mapped to this map. The operating angle of the camshaft is obtained by substituting the rotational speed and the opening degree of the nozzle vane 51. Further, the VVT advance amount is also calculated in the same manner as in step S105. The camshaft operating angle and the VVT advance amount calculated in this step are values that allow air sucked into the cylinder of the internal combustion engine 1 to blow through, and values that are required to discharge excess internal EGR from the cylinder. . Further, the optimal ignition timing is calculated. This ignition timing is obtained in advance through experiments and mapped.

  In step S402, the ECU 10 calculates the main injection amount and the sub injection amount. The main injection amount is a fuel amount necessary for generating the torque required at the time of acceleration, and the sub injection amount is a fuel amount necessary for sufficiently increasing the supercharging pressure. These are obtained in advance by experiments and mapped from the relationship between the engine speed and the intake air amount.

In this way, the drivability can be further improved by quickly increasing the supercharging pressure and quickly accelerating.
As described above, according to the present embodiment, the camshaft operating angle is set in accordance with the VNT opening (closed opening) even in the VNT open region during acceleration operation, and the intake air enters the exhaust system. The intake air amount of the internal combustion engine 1 can be increased by blowing through. Further, by using the sub-injection together, the supercharging pressure can be increased more quickly and the drivability can be improved.

It is a figure which shows schematic structure of the internal combustion engine to which the internal combustion engine with a supercharger which concerns on an Example, its intake-exhaust system, and a supercharger. It is sectional drawing which shows the structure of a variable capacity type | mold turbocharger. FIG. 2A shows the case where the nozzle vane is open, and FIG. 2B shows the case where the nozzle vane is closed. It is a schematic block diagram (longitudinal sectional view) of a variable valve mechanism according to an embodiment. It is a schematic block diagram (top view) of the variable valve mechanism by an Example. It is the figure which showed the relationship between an engine speed, an engine generation torque, and the open / close state of a nozzle vane. It is the figure which showed the state of the engine speed and engine generated torque at the time of transient operation. It is the figure which showed the relationship between the opening degree of a nozzle vane (VNT opening degree), and a back pressure. It is the figure which showed the relationship between the intake air amount of an internal combustion engine, VVT advance amount, and engine speed. It is the figure which showed the relationship between the opening degree of a nozzle vane (VNT opening degree), and the amount of internal EGR. It is the time chart which showed transition of the opening-and-closing state (VNT opening degree) of a nozzle vane, the actual intake air amount at the time of a transient operation, and the intake air amount obtained on a map. 4 is a time chart showing transitions of an open / close state (VNT opening degree), intake air amount, and VVT advance amount of a nozzle vane according to Example 1; 3 is a flowchart of VVT advance angle control according to the first embodiment. 6 is a time chart showing changes in the open / close state (VNT opening), intake air amount, and VVT advance amount of a nozzle vane according to Example 2; 6 is a flowchart of VVT advance angle control according to the second embodiment. 3 is a control map showing a relationship among an engine speed, an intake air amount of an internal combustion engine, and a camshaft operating angle. It is the figure which showed the relationship between the working angle of a camshaft, the amount of intake air, and engine speed. It is the time chart which showed transition of the opening-and-closing state (VNT opening degree) of a nozzle vane at the time of transition, and intake air quantity. 12 is a flowchart of camshaft operating angle control according to a third embodiment. It is the time chart which showed transition of the opening-and-closing state (VNT opening degree) of a nozzle vane at the time of transition, and intake air quantity. 6 is a flowchart of camshaft operating angle control when a camshaft operating angle and a VVT advance amount are set so that intake air is blown through, and sub-injection is also used.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Internal combustion engine 2 Intake pipe 3 Exhaust pipe 4 Turbocharger 4a Compressor housing 4b Turbine housing 4c Exhaust turbine 5 Intake throttle valve 6 Communication path 7 Wastegate valve 8 Diaphragm 10 ECU
11 Accelerator pedal 12 Accelerator opening sensor 13 Crank position sensor 14 Pressure sensor 15 Air flow meter 20 Intake valve 21 Intake side cam 22 Intake side camshaft 23 Intake side pulley 24 Variable rotation phase mechanism (intake side VVT)
25 Intake side cam angle sensor 26 Exhaust valve 27 Exhaust side cam 28 Exhaust side camshaft 29 Exhaust side pulley 30 Variable rotation phase mechanism (exhaust side VVT)
31 Exhaust side cam angle sensor 32 Crankshaft 33 Crank side pulley 34 Timing belt 51 Nozzle vane 52 Actuator

Claims (2)

A supercharging pressure variable mechanism capable of changing the rotational speed of the exhaust turbine of the supercharger according to the operating state of the internal combustion engine;
A variable valve mechanism capable of changing a valve opening characteristic of at least one of an intake valve or an exhaust valve of an internal combustion engine;
With
During normal operation of the internal combustion engine, the variable supercharging pressure mechanism is operated at a low supercharging pressure region operated at a relatively low supercharging pressure and at a supercharging pressure higher than the low supercharging pressure region. The variable valve mechanism operates in accordance with each of the supercharging pressure regions of the high supercharging pressure region, and the variable valve mechanism has a valve opening characteristic corresponding to each of the low supercharging pressure region and the high supercharging pressure region. In the internal combustion engine with a supercharger provided,
During acceleration operation of the internal combustion engine, the supercharging pressure changing mechanism operates corresponding to a high supercharging pressure region, and the variable valve mechanism allows the intake air to blow from the intake system to the exhaust system in the low supercharging pressure region. At least one of the working angle and supercharged internal combustion engine, characterized in that the set according to Oh Barappu amount to the opening of the nozzle vanes provided in the boost pressure changing mechanism of the intake valve or exhaust valve.   The supercharged internal combustion engine according to claim 1, wherein secondary fuel injection is performed in an expansion stroke or an exhaust stroke after the main injection of fuel.

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