JP2010043579A - Internal combustion engine with turbocharger - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To properly recover exhaust gas into an accumulating container even when power is generated actively by an internal combustion engine with a turbocharger including the accumulating container connectable to an exhaust gas passage. <P>SOLUTION: The internal combustion engine 10 with the turbocharger 46 includes the accumulating container 64 connectable to the exhaust gas passage on the upstream side of a turbine 38; an exhaust flow control means 54 for controlling exhaust gas flow into a turbine wheel 36 of the turbine 38; and an intake flow control means 26 for controlling intake flow into a cylinder 14 of the internal combustion engine 10. The intake flow control means 26 is adapted to reduce intake when exhaust gas is recovered into the accumulating container 64 more than when the exhaust gas is not recovered. The exhaust gas flow control means 54 operates to increase the rotational speed of the turbine 38 when the exhaust gas is recovered into the accumulating container 64 more than when the exhaust gas is not recovered. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an internal combustion engine with a turbocharger, and more particularly, to an internal combustion engine with a turbocharger configured to be able to collect exhaust gas in a pressure accumulating vessel.

  Patent Document 1 discloses a recovery device that increases the pressure of an exhaust passage of an internal combustion engine and recovers the exhaust having the increased pressure in a pressure accumulation container (pressure accumulation tank). In this recovery device, the pressure in the exhaust passage upstream of the exhaust throttle valve is increased by closing the exhaust throttle valve provided in the exhaust passage when performing fuel cut during deceleration. Then, the exhaust gas having the increased pressure, that is, the pressure energy, is collected in the pressure accumulating vessel by communication between the exhaust passage upstream of the exhaust throttle valve and the pressure accumulating vessel.

  On the other hand, it is already known to mount a supercharger on an internal combustion engine. Among the turbochargers, there is a turbocharger that rotates a turbine wheel of a turbine by exhaust gas and rotates a compressor wheel of a compressor by rotation of the turbine wheel to supercharge an internal combustion engine. There are various types of turbochargers, for example, a type in which a wastegate valve is provided in a bypass passage that bypasses a turbine wheel. In this type of internal combustion engine with a turbocharger, for example, when the pressure in the intake passage on the downstream side of the compressor of the turbocharger is higher than a predetermined pressure, the wastegate valve is opened to appropriately ensure the operation of the turbocharger. The excess exhaust is released (discarded) to the exhaust passage downstream of the turbine.

JP 2007-138812 A

  Incidentally, in recent years, attempts have been made to save energy in various fields including the field of automobile technology. Against this background, for example, as described above, exhaust that is not used for the operation of the turbine of the turbocharger due to the opening of the wastegate valve is used for the operation or operation assistance of various devices. There is expected.

  In order to use such exhausted exhaust for the operation of various devices, for example, as in the device described in Patent Document 1, such an accumulator is capable of communicating such exhaust with the exhaust passage. It is desirable to recover once. However, when power is actively generated in the internal combustion engine as described above, if the exhaust throttle valve is closed to collect the exhaust gas in the pressure accumulating vessel, a change in the intake air amount of the internal combustion engine is expected. There is a problem that it becomes difficult or it becomes difficult to predict a change in pumping loss. As a result, torque fluctuations of the internal combustion engine occur, and drivability may deteriorate.

  Accordingly, the present invention has been made in view of such a point, and the object thereof is an internal combustion engine with a turbocharger provided with a pressure accumulating vessel capable of communicating with an exhaust passage, even when power is actively generated. The purpose is to properly recover the exhaust into the pressure accumulator. The time when the internal combustion engine is actively generating power is specifically when the piston is reciprocated by the combustion pressure of the air-fuel mixture.

  In order to achieve the above object, an internal combustion engine with a turbocharger according to the present invention is an internal combustion engine with a turbocharger including a turbine provided in an exhaust passage and a compressor connected to the turbine and provided in an intake passage. An accumulator vessel that can communicate with an exhaust passage on the upstream side of the turbine, an exhaust flow control means that controls the flow of exhaust to the turbine wheel of the turbine, and an intake flow control means that controls the flow of intake air to the cylinders of the internal combustion engine And when it collects exhaust gas in the said accumulator, it has an intake air flow control means which throttles intake air compared with the case where this exhaust gas recovery is not performed, It is characterized by the above-mentioned.

  The exhaust flow control means may work so that when the exhaust gas is collected in the pressure accumulating vessel, the rotational speed of the turbine is higher than when the exhaust gas is not collected.

  Further, the intake flow control means includes any one of an intake throttle valve and a swirl control valve, and valve control means for controlling any one of the valves, and the valve control means includes the accumulator When exhaust recovery is performed in the container, the opening degree of either one of the valves may be controlled so that the opening degree is more closed than the opening degree when the exhaust recovery is not performed.

  In addition to or in place of this, the intake flow control means includes a variable valve mechanism that varies at least one of the valve timing and the lift amount of the intake valve, and the variable valve mechanism is disposed in the pressure accumulating vessel. When exhaust recovery is performed, it is preferable to change at least one of the valve timing and the lift amount of the intake valve so that the intake efficiency is lower than the intake efficiency when the exhaust recovery is not performed.

  According to the present invention, in an internal combustion engine equipped with a turbocharger, the exhaust flow control means for controlling the flow of exhaust gas to the turbine wheel of the turbine and the intake flow control means for controlling the flow of intake air to the cylinder of the internal combustion engine are operated or operated. The exhaust gas can be collected in the pressure accumulating vessel. With this configuration, the present invention is a turbocharged internal combustion engine equipped with a pressure accumulating vessel that can communicate with the exhaust passage, and even when power is actively generated, it is possible to appropriately recover the exhaust gas into the pressure accumulating vessel. To.

  Specifically, in the internal combustion engine with a turbocharger, the present invention conventionally opens, for example, a waste gate valve or an opening degree of a variable nozzle vane of a turbocharger turbine so as to reduce the rotational speed of the turbine in order to adjust the engine output. When the (VN opening) is set to the open side, the exhaust gas can be collected in the pressure accumulating vessel. In such a case, when recovering exhaust gas, close the wastegate valve or reduce the VN opening to increase the pressure in the exhaust passage on the upstream side of the turbine to increase the turbine rotational speed and Make the pressure rise excessively. However, if the supercharging pressure actually increases excessively, the engine output will become undesired by the driver. To avoid this, the throttle valve, swirl control valve, etc. are closed compared to normal times. By controlling to the side, the amount of intake air flowing into the cylinder is limited, and the engine output is adjusted.

  Preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. First, the first embodiment will be described. FIG. 1 shows a schematic configuration of an internal combustion engine system 10 for a vehicle to which the first embodiment is applied. The internal combustion engine 10 is a type of internal combustion engine, that is, a diesel engine, that spontaneously ignites by directly injecting light oil as fuel from a fuel injection valve 12 into a combustion chamber in a compressed state.

  An intake port that faces the combustion chamber of the cylinder 14 and defines a part of the intake passage 16 is formed in the cylinder head and is opened and closed by an intake valve. An intake manifold 18 that defines a portion of the intake passage 16 is connected to the cylinder head, and an intake pipe 20 that also defines a portion of the intake passage 16 is connected to the upstream side thereof. An air cleaner 22 is provided on the upstream end side of the intake pipe 20 in order to remove dust and the like in the air guided to the intake passage 16. A throttle valve 26 whose opening is adjusted by the throttle actuator 24 is provided in the intake passage 16.

  On the other hand, an exhaust port that faces the combustion chamber of the cylinder 14 and defines a part of the exhaust passage 28 is formed in the cylinder head and is opened and closed by an exhaust valve. An exhaust manifold 30 that defines a part of the exhaust passage 28 is connected to the cylinder head, and an exhaust pipe 32 that also defines a part of the exhaust passage 28 is connected to the downstream side thereof. A catalytic converter 34 filled with an exhaust purification catalyst is provided in the middle of the exhaust passage 28.

  Although not shown in the figure, the valve operating mechanism that is the drive mechanism for the intake valve and the exhaust valve is individually selected in synchronization with the rotation of the crankshaft to which the piston is connected via the connecting rod. It is a variable valve mechanism that can be controlled by the opening degree and timing. Therefore, this valve operating mechanism can change at least one of the valve timing and the lift amount of each intake / exhaust valve. Specifically, the valve operating mechanism includes solenoids individually provided for the intake valve and the exhaust valve. The valve mechanism can realize a valve overlap in which the intake valve and the exhaust valve open simultaneously. Instead of such a configuration, a variable valve timing mechanism (VVT) that can arbitrarily change the valve timing and cam profile by switching, for example, a plurality of types of cams applied to a single valve by hydraulic pressure, as a valve mechanism. ; Variable Valve Timing mechanism) can also be used.

  Further, a turbine 38 including a turbine wheel 36 that is rotationally driven by exhaust gas is provided in the exhaust passage 28. Correspondingly, a compressor 44 including a compressor wheel 42 that is coaxially connected to the turbine wheel 36 of the turbine 38 via the rotating shaft 40 and is rotated by the rotational force of the turbine wheel 36 is provided in the intake passage 16. ing. That is, the internal combustion engine 10 is provided with a turbocharger 46 having a turbine 38 that extracts exhaust energy, and a compressor 44 that is connected to the turbine 38 and supercharges the internal combustion engine 10 by the exhaust energy extracted by the turbine 38. An internal combustion engine with a turbocharger 46. An intercooler 48 is provided on the downstream side of the compressor 44 in order to cool the air compressed by the compressor 44.

  The turbocharger 46 is a variable nozzle turbocharger in which a plurality of variable nozzle vanes (VN) 50 are disposed in a turbine 38. That is, a plurality of vanes 50 are disposed at the exhaust inlet of the turbine 38 around the turbine wheel 36 so as to surround the turbine wheel 36. As a vane drive mechanism for driving the plurality of vanes 50, a rod 52, a drive ring 54, an actuator 56, and the like are provided. The angles of the plurality of vanes 50 are adjusted simultaneously by the actuator 56 via the rod 52 and the drive ring 54. The pressure on the upstream side of the plurality of vanes 50 is adjusted by adjusting the angle of the vanes 50 to the closed side so that the opening degree of the flow path (VN opening degree) determined by the angles of the plurality of vanes 50 is closed. As a result, the flow rate of the exhaust gas introduced into the turbine wheel 36 increases. On the other hand, by adjusting the angle of the vane 50 to the open side so that the VN opening is on the open side, the pressure on the upstream side of the plurality of vanes 50 is reduced, and the flow rate of the exhaust gas introduced into the turbine wheel 36 is Become slow. That is, since the angles of the plurality of vanes 50 are variable (VN opening is variable), the effective area of the flow path formed in the turbine 38 is variable.

  Here, the actuator 56 that drives the rod 52 that is a plurality of operating shafts for driving the vanes 50 is a negative pressure actuator. When the rod 52 is driven by the actuator 56, the drive ring 54 is rotated by a predetermined angle around the rotation shaft 40, and the plurality of vanes 50 are uniformly at the same angle based on the rotation of the drive ring 54. Moved. Various mechanisms are well known through such a link mechanism including each member including the rod 52 and the drive ring 54, and description thereof is omitted here. The actuator 56 includes an air chamber, a negative pressure chamber into which negative pressure can be introduced from a negative pressure source, a negative pressure introduction valve for adjusting the amount of negative pressure introduced into the negative pressure chamber, and the negative pressure airtightly. A known diaphragm having a pressure chamber and an air chamber separated from each other and connected to a rod 52, and a spring that generates a biasing force that presses the diaphragm from the negative pressure chamber toward the atmospheric pressure chamber. Actuator. The diaphragm is displaced according to the negative pressure introduced into the negative pressure chamber of the actuator 56. And the rod 52 which is an action | operation axis | shaft can drive the several vane 50 to both directions simultaneously with the displacement.

  Of the exhaust passage 28, the exhaust passage J upstream of the turbine 38 is connected to a pipe 62 defined by a pipe member 60, so that the exhaust passage J can communicate with the inside of the pressure accumulating vessel 64. Has been. It should be noted that the pressure accumulating vessel 64 may be directly communicable with any place, for example, the exhaust manifold 30 as long as it is in the exhaust passage J. The diameter of the pipeline 62 is smaller than the diameter of the exhaust passage 28. A flow rate adjustment valve 66 is provided in the pipe line 62 for adjusting the communication state between the pressure accumulating vessel 64 and the exhaust passage J. When the flow rate adjusting valve 66 is opened, the pressure accumulating vessel 64 and the exhaust passage 28 communicate with each other, and when the flow rate adjusting valve 66 is closed, the communication between the accumulating vessel 64 and the exhaust passage 28 is blocked. Thus, the inside of the pressure accumulating vessel 64 is substantially sealed. However, the flow control valve 66 is driven by an actuator 68. Here, the flow rate adjusting valve 66 is a poppet type valve.

  Further, an exhaust throttle valve 70 is provided in the exhaust passage 28. Here, the exhaust throttle valve 70 is provided in the exhaust passage on the downstream side of the turbine 38 and on the upstream side of the catalytic converter 34, but may be provided in another part of the exhaust passage 28. However, as in the first embodiment, the inside of the pressure accumulator 64 can be communicated with the exhaust passage upstream of the exhaust throttle valve 70. Here, the exhaust throttle valve 70 is a butterfly valve and is driven by an actuator 72. The exhaust throttle valve 70 effectively clogs the exhaust gas flowing through the exhaust passage 28, that is, burned gas (including combustion gas) and air, when the exhaust throttle valve 70 is closed, and downstream of such fluid to the exhaust throttle valve 70. It functions as a shut-off valve that generally shuts off the flow of air. The exhaust throttle valve 70 may be a valve having another configuration, for example, a valve having a configuration that completely closes the portion when the valve is closed.

  As will be described later, the pressure (pressure energy) of the exhaust passage 28, that is, the exhaust gas having the pressure, is recovered from the exhaust passage 28 into the pressure accumulating vessel 64 while moving the exhaust gas via the pipe 62. On the other hand, the pressure, that is, the exhaust gas stored in the pressure accumulating vessel 64 is discharged from the pressure accumulating vessel 64 to the exhaust passage 28 via the pipe 62 and used. That is, in the first embodiment, exhaust recovery into the pressure accumulating vessel 64 and exhaust discharge from the same are performed via the same pipe line 62.

  Here, the exhaust gas collected in the pressure accumulating vessel 64 is discharged to the exhaust passage J through the pipe line 62 particularly when acceleration is requested, in the early stage of acceleration. The discharged exhaust or pressure is used to drive the turbine wheel 36 to rotate. Thereby, the response of the turbocharger 46 is improved, in other words, the transient performance is improved. However, when the exhaust gas in the pressure accumulating vessel 64 is used for assisting the operation of the turbocharger 46 in this way, the exhaust gas in the accumulator vessel 64 passes through the exhaust passage K upstream of the turbine wheel 36 including the exhaust passage other than the exhaust passage J. It should be supplied.

  The internal combustion engine 10 includes various sensors that electrically output signals for obtaining (detecting or estimating) various values in an electronic control unit (ECU) 80. Here, some of them will be specifically described. An air flow meter 82 for detecting the amount of intake air is provided in the intake passage 16. An intake air temperature sensor 84 for detecting the temperature of intake air (intake air) is provided in the vicinity of the air flow meter 82, and an intake air temperature sensor 86 for detecting the temperature downstream of the intercooler 48 is also provided. Further, a pressure sensor 88 for detecting intake pressure, that is, supercharging pressure is provided. Further, an accelerator opening sensor 92 for detecting a position corresponding to the depression amount of the accelerator pedal 90 operated by the driver, that is, an accelerator opening is provided. A throttle position sensor 94 for detecting the opening of the throttle valve 26 is also provided. A crank position sensor 96 for detecting a crank rotation signal of a crankshaft connected to the piston via a connecting rod is attached to a cylinder block (or its vicinity) where the piston reciprocates. Here, the crank position sensor 96 is also used as an engine speed sensor for detecting the engine speed (engine speed). Further, a pressure sensor 98 for detecting the pressure in the exhaust passage J is provided. Further, a pressure sensor 100 for detecting the pressure in the pressure accumulating vessel 64 is also provided. Further, a temperature sensor 102 for detecting the coolant temperature of the internal combustion engine 10 is provided. Furthermore, a vehicle speed sensor 104 for detecting the vehicle speed is also provided.

  The ECU 80 is configured by a microcomputer including a CPU, ROM, RAM, A / D converter, input interface, output interface, and the like. The various sensors are electrically connected to the input interface. Based on the output signals (detection signals) from these various sensors, the ECU 80 is electrically operated from the output interface (drive signal) so that the internal combustion engine 10 can be smoothly operated or operated according to a preset program. ) Is output. In this way, the valve timing and lift amount of the intake / exhaust valve, the operation of the fuel injection valve 12, the opening degree of the throttle valve 26, the flow rate adjusting valve 66, the exhaust throttle valve 70, the angle of the vane 50, and the like are controlled. However, the ECU 80 outputs operation signals to the actuators 24, 68, 72, and 56 in order to control the opening degree of the throttle valve 26, the flow rate adjustment valve 66, and the exhaust throttle valve 70 and the angle of the vane 50.

  In the first embodiment, the intake flow control means includes the throttle valve 26 and the throttle valve control means including the actuator 24 and a part of the ECU 80. Further, the exhaust flow control means includes a plurality of vanes 50 and a vane drive mechanism including a part of the actuator 56 and the ECU 80 so that the angles of the vanes 50 can be changed. Further, the required load determination unit includes a part of the ECU 80.

In the internal combustion engine 10, the intake air amount obtained based on the output signal from the air flow meter 82, the engine rotational speed obtained based on the output signal from the crank position sensor 96, that is, the engine load and the engine rotational speed are represented. Normally, a fuel injection amount (fuel amount) or the like is set based on the engine operating state. Based on the fuel injection amount and the like, fuel is injected from the fuel injection valve 12.

  However, in the internal combustion engine 10, the engine rotational speed obtained based on the output signal from the crank position sensor 96 is equal to or higher than a predetermined rotational speed (fuel cut rotational speed), and based on the output signal from the accelerator opening sensor 92. The fuel injection from the fuel injection valve 12 is set to be stopped (fuel cut) when the accelerator opening required in this way is 0%, that is, when the accelerator pedal 90 is not depressed. That is, the fuel cut is performed when the engine rotational speed is in a predetermined rotational speed region set in advance and the accelerator opening is fully closed while the vehicle is running. However, when such a fuel cut state continues and the engine rotational speed decreases and reaches another predetermined rotational speed (fuel cut return rotational speed), fuel injection is resumed. In addition, when the internal combustion engine 10 is in a fuel cut state because the above conditions are satisfied, the accelerator pedal 90 is depressed and the accelerator opening increases to the open side and exceeds 0%. Fuel injection is resumed. In addition, when the internal combustion engine 10 is in the fuel cut state, it generally corresponds to the time of deceleration.

  The throttle valve 26 is controlled to be fully open when the internal combustion engine 10 is started, and is controlled to be fully closed when the internal combustion engine 10 is stopped. During normal traveling, the opening of the throttle valve 26 becomes an appropriate opening according to the engine state that can be determined by the engine speed, the supercharging pressure, the engine load, and / or the intake air amount, and the cooling water temperature. To be controlled.

Further, the angle of the plurality of vanes 50, that is, the VN opening is controlled based on the engine operating state. For example, based on the output signal from the pressure sensor 88 provided in the intake passage on the downstream side of the throttle valve 26, the supercharging pressure (target supercharging pressure) that is set in accordance with the engine operating state and that is targeted for control. The angles of the plurality of vanes 50 are controlled so that the supercharging pressures obtained in this manner match. Alternatively, the intake air amount determined based on the output signal from the air flow meter 82 matches the intake air amount targeted for control (target intake air amount) set according to the engine operating state. The angles of the plurality of vanes 50 are controlled. Here, the VN opening is increased so that the operating region to which the engine operating state belongs is on the high-load high-rotation side, so that the flow path is expanded compared to when the operating region is on the low-load low-rotation side. However, in a transition period in which the accelerator pedal 90 is depressed and the vehicle is accelerated, the engine operating state is set such that the VN opening is once reduced to increase the exhaust flow velocity and increase the rotational speed of the turbine wheel 36. The VN opening determined based on the correction is corrected. Here, in the transition period in which the vehicle is accelerated, the angles of the plurality of vanes 50 are controlled so that the VN opening is once fully closed. Note that the flow path area defined by the plurality of vanes 50 when the VN opening is fully closed is, for example, several percent of the flow path area when the VN opening is fully closed without being completely closed.

  By the way, during normal travel, the exhaust throttle valve 70 is controlled so as to be fully opened, so that all exhaust flowing through the exhaust passage 28 passes through the catalytic converter 34 and is released to the outside air. On the other hand, when the first predetermined condition for exhaust recovery is satisfied, the exhaust throttle valve 70 is controlled to be in a closed state, and the exhaust flowing through the exhaust passage 28 is generally blocked. The exhaust gas thus blocked is effectively utilized to recover exhaust gas (pressure energy recovery), that is, to fill the pressure accumulating vessel 64 with gas.

  Hereinafter, exhaust recovery will be described in detail with reference to the flowchart of FIG. However, the flowchart of FIG. 2 is repeated every predetermined time, for example, approximately every 8 ms. As will be apparent from the following description, the exhaust gas recovered in the pressure accumulating vessel 78 according to the flowchart of FIG. 2 is mainly composed of air.

  However, in the control described below with reference to FIG. 2, during the fuel cut, the exhaust throttle valve 70 of the exhaust passage 28 is closed, and the pressure in the exhaust passage upstream of the exhaust throttle valve 70 becomes the pressure in the pressure accumulator 64. In this example, the exhaust gas, that is, the pressure energy of the exhaust gas, is collected into the pressure accumulating vessel 64 via the flow rate control valve 66 when the above is reached.

  When the internal combustion engine 10 is activated, the ECU 80 first determines in step S201 whether the recovery flag is “1”, that is, whether it is ON. Here, the recovery flag being “1” indicates that the first predetermined condition for exhaust recovery is satisfied. On the other hand, when it is “0”, it indicates that the first predetermined condition for exhaust gas recovery is not satisfied. Since the recovery flag is reset in the initial state, a negative determination is made here. In the first embodiment, the fact that the first predetermined condition for exhaust recovery is satisfied means that the internal combustion engine 10 is in a fuel cut state (being fuel cut), as will be apparent from the following description. Two requirements that the pressure in the pressure accumulating vessel 64 is equal to or lower than a predetermined pressure are satisfied.

  If a negative determination is made in step S201, it is determined in next step S203 whether or not a fuel cut is in progress. Specifically, whether or not the fuel is being cut is determined based on whether or not the fuel injection amount is “0”. However, for example, it may be substituted by determining whether or not the above-described fuel cut execution condition is satisfied. Note that during normal travel, in general, a fuel injection amount greater than “0” is introduced and fuel injection is performed in order to produce a predetermined output by the internal combustion engine 10. Therefore, in such a case, a negative determination is made in step S203.

  If an affirmative determination is made in step S203 that the fuel cut is in progress, then in step S205, the pressure in the pressure accumulator 64 (internal pressure in FIG. 2) is a pressure allowed for the pressure accumulator 64 and is a predetermined pressure. It is determined whether the pressure is equal to or lower than an upper limit pressure that is determined in advance and stored in the ROM. For one thing, when a sufficient amount of pressure, that is, exhaust gas is stored in the pressure accumulating vessel 64, further exhaust recovery is prevented. The pressure in the pressure accumulating vessel 64 is obtained based on an output signal from the pressure sensor 100. However, here, as the upper limit pressure, a value of 400 kPa is set as the gauge pressure, but other pressure values may be used.

  If an affirmative determination is made in step S205, the recovery flag is set to “1” in step S207, assuming that the first condition of exhaust recovery is satisfied. As a result, the exhaust recovery control is prioritized over the normal control.

  In the next step S209, the throttle valve 26 is actuated to the actuator 24 so that the throttle valve 26 opens to the fully open position so that the throttle valve 26 does not have an opening for normal driving (normal opening) but an opening for recovery of exhaust (collection opening). A signal is output. Further, an operation signal is output to the actuator 68 so that the flow rate adjustment valve 66 is closed. Further, an operation signal is output to the actuator 72 so that the exhaust throttle valve 70 is closed. Thus, the routine ends.

  In step S201 of the routine after the collection flag is set to “1” in step S207, an affirmative determination is made because the collection flag is “1”. If an affirmative determination is made in step S201, it is determined in the next step S211 whether or not a fuel cut is in progress as in step S203. If an affirmative determination is made here, then in step S213, it is determined whether or not the pressure in the pressure accumulating vessel 64 is equal to or lower than the upper limit pressure in the same manner as in step S205. Note that the determinations in steps S211 and S213 are performed in order to end exhaust recovery when the first predetermined condition for exhaust recovery is not satisfied after the recovery flag is set to “1” in step S207. This is because of the control.

  If an affirmative determination is made in step S213, it is then determined in step S215 whether or not the pressure in the pressure accumulating vessel 64 is equal to or lower than the pressure in the exhaust passage upstream of the exhaust throttle valve 70 ("back pressure" in FIG. 2). The At this time, since the exhaust throttle valve 70 is already controlled to close, the pressure (pressure energy) of the exhaust clogged by the exhaust throttle valve 70 increases with time. Then, in order to examine whether or not the pressure has increased to such an extent that exhaust gas recovery is possible, the determination in step S215 is performed. If a negative determination is made in step S215, an operation signal is output to the actuator 68 so that the flow rate adjustment valve 66 is closed in the next step S217. This means that when the flow control valve 66 is already closed, the flow control valve 66 is maintained in the closed state. On the other hand, if the determination in step S215 is affirmative, in the next step S219, an actuation signal is output to the actuator 68 so that the flow rate adjustment valve 66 is opened (the valve opening is controlled). Accordingly, the exhaust gas having an increased pressure in the exhaust passage upstream of the exhaust throttle valve 70 is recovered in the pressure accumulating vessel 64 through the communication passage 62. This exhaust gas recovery is generally continued unless a negative determination is made in step S211 or step S213.

  If a negative determination is made in either step S211 or step S213 during exhaust gas recovery, control for terminating exhaust gas recovery is performed. If a negative determination is made in any of them, the throttle valve 26 is controlled so as to have a normal opening in the next step S221. Further, an operation signal is output to the actuator 68 so that the flow rate adjustment valve 66 is closed. Further, an operation signal is output to the actuator 72 so that the exhaust throttle valve 70 is opened. In step S223, the recovery flag is set to “0”, and the routine ends. As a result, the internal combustion engine 10 is returned to a normal control state in which exhaust recovery is not performed.

  By the way, in a general turbocharger, when the engine rotation speed belongs to a low rotation range, the rotation speed of the turbocharger is low because the flow rate of the exhaust gas is small. Therefore, if the accelerator pedal 90 is depressed at that time, the accelerator pedal 90 There is a time delay, i.e., a time lag, from when the engine is depressed until the intake air supercharging effect appears. Therefore, in the transition period in which the accelerator pedal 90 is depressed and the vehicle is accelerated, the operation of the turbocharger 46 is assisted in order to quickly increase the supercharging pressure. The operation assistance of the turbocharger 46 will be described in detail according to the flowchart of FIG. However, the flowchart of FIG. 3 is repeated every predetermined time, for example, approximately every 8 ms.

  However, the control described below with reference to FIG. 3 is directed to the turbine wheel 36 of the turbine 38 in order to improve the response of the turbocharger 46 by increasing the rate of increase of the turbine rotation speed when acceleration is requested. In this example, the exhaust gas is supplied from the pressure accumulating vessel 64.

  First, in step S301, the ECU 80 determines whether or not the recovery flag is “0”, that is, OFF. Since the flag is reset in the initial state, an affirmative determination is made here. If a negative determination is made in step S301, the routine ends.

  If an affirmative determination is made in step S301, in the next step S303, it is determined whether or not the assist flag is “1”, that is, ON. Here, the fact that the assist flag is “1” means that the operation assist condition of the turbocharger 46 is satisfied, while that that is “0” means that the turbocharger 46 is. This indicates that the operation assist condition is not satisfied. Since the assist flag is reset in the initial state, a negative determination is made here.

  If a negative determination is made in step S303, in the next step S305, it is determined whether or not the engine rotational speed is equal to or lower than a predetermined rotational speed. When the engine rotational speed is higher than the predetermined rotational speed, there is no need for assistance regarding the operation of the turbocharger 46. Therefore, when the engine rotational speed exceeds the predetermined rotational speed, a negative determination is made in step S305, and the routine ends. . On the other hand, if an affirmative determination is made in step S305 that the engine rotational speed is equal to or lower than the predetermined rotational speed, the process proceeds to step S307. For example, the predetermined rotation speed in the determination in step S305 is 3000 rpm.

  In step S307, it is determined whether or not acceleration, that is, whether or not there is an acceleration request. This determination is included in determining whether or not the required load on the internal combustion engine 10 has increased by the required load determination means. The determination as to whether or not the vehicle is accelerating is equivalent to obtaining the acceleration start time and is performed based on the accelerator opening. When the accelerator opening is greater than or equal to a predetermined value and the accelerator opening is increased, the amount of change in the unit predetermined time, that is, the opening speed (accelerator opening opening speed) exceeds the predetermined speed. Sometimes, the ECU 80 determines that acceleration, that is, there is an acceleration request. More specifically, the ECU 80 obtains the accelerator opening based on the output signal from the accelerator opening sensor 92, the accelerator opening is, for example, 20% or more, and the accelerator opening opening speed. However, when it exceeds the predetermined speed, which is a reference speed that is set in advance and stored in a storage device such as a ROM, it is determined that acceleration is present. Note that the determination in step S307 may be performed using different values, criteria, or the like. If an affirmative determination is made in step S307, a determination in step S309 is then performed. If a negative determination is made in step S307, the routine ends.

  In step S309, it is determined whether or not the pressure in the pressure accumulation container 64 is equal to or higher than a predetermined pressure. The predetermined pressure is a pressure corresponding to a minimum exhaust amount required to assist the operation of the turbocharger 46, and is obtained in advance by experiments and stored in the ROM. If a negative determination is made in step S309, the routine ends.

  On the other hand, if an affirmative determination is made in step S309, the assist flag is set to “1” in step S311 because the operation assist condition of the turbocharger 46 is satisfied. In step S313, an operation signal is output to the actuator 68 so that the flow rate adjustment valve 66 is opened (the flow rate adjustment valve 66 is controlled to be opened). In this way, the operation assist of the turbocharger 46 is started.

  When the flow rate adjustment valve 66 is opened, the exhaust in the pressure accumulating vessel 64 is supplied to the exhaust passage K upstream of the turbine wheel 36. The supply of exhaust gas from the pressure accumulating vessel 64 promotes an increase in turbine rotational speed. Therefore, it is possible to reduce the turbo lag. In addition, when there are many oxygen components in exhaust_gas | exhaustion in the pressure accumulation container 64, combustion of the unburned fuel in exhaust_gas | exhaustion from the cylinder 14 is promoted by supply of such exhaust_gas | exhaustion from the pressure accumulation container 64. Therefore, it is possible to supply the turbine wheel 36 with an exhaust having a higher pressure and a higher expansion energy. Therefore, the rotational speed of the turbine wheel 36 can be rapidly increased, and the turbo lag can be more reliably reduced.

  On the other hand, in the next and subsequent routines, since the collection flag is “0” and the assist flag is “1”, affirmative determination is made in steps S301 and S303, respectively. In the next step S315, as in step S305, it is determined whether or not the engine rotational speed is equal to or lower than a predetermined rotational speed.

  If an affirmative determination is made in step S315, it is determined in the next step S317 whether or not the assist time has elapsed. Here, the time to be determined is an elapsed time from when the flow rate adjustment valve 66 is opened and the pipe line 62 is opened. Here, the ECU 80 measures the time from the time when it reached Step S311 with the built-in timer means, and adopts this time by assuming it as the time to be determined. The assist time serving as a determination criterion is a predetermined time obtained and set in advance by experiments. Here, the assist time is not a variable but a fixed value and is stored in a storage device such as a ROM. However, the assist time used for the determination in step S317 may be variable, and may be determined based on the engine operating state when acceleration is requested, the pressure in the exhaust passage K upstream of the turbine wheel 36, and the like. .

  If an affirmative determination is made in step S317 that the assist time has not elapsed, it is then determined in step S319 whether or not the pressure in the pressure accumulating vessel 64 is equal to or higher than the predetermined pressure in the same manner as in step S309. If the determination is affirmative here, the routine ends.

  By making a negative determination in any of steps S315 to S319, control for ending the operation assist of the turbocharger 46 is performed. If a negative determination is made in any of steps S315 to S319, an operation signal is output to the actuator 68 so that the flow rate adjustment valve 66 is closed in step S321. In step S323, the assist flag is set to “0”. As a result, the routine ends. This resets the timer means.

  However, once the operation assistance of the turbocharger 46 is started, whether or not to end the operation is determined by accelerating (requesting) in addition to all or any of the determinations in steps S315 to S319. A determination may be made whether or not is continued. This is because it is no longer necessary to assist the operation of the turbocharger 46 when acceleration is not continued. Specifically, the accelerator opening changes from the accelerator opening when it is determined that there is an acceleration request to the closing side by a predetermined amount, or the opening degree of the accelerator opening becomes negative and the magnitude exceeds the predetermined amount. When it is determined that the acceleration is not continued, the above-described control (step S321 and step S323) for ending the operation assist may be performed, assuming that the acceleration is not continued.

  By performing the operation assist of the turbocharger 46 in this way, as shown by a solid line α in FIG. 4, the pressure in the exhaust passage J upstream of the turbine 38 is quickly increased, and the transient response of the turbocharger 46 is improved. The pressure in the intake passage 16 can be quickly increased to the target boost pressure. Note that the graph of FIG. 4 conceptually represents an example of a change in the pressure of the exhaust passage J upstream of the turbine 38 with respect to time. The solid line α indicates that acceleration is started at time t1, the flow rate adjustment valve 66 is opened, operation assistance of the turbocharger 46 is started, operation assistance is performed until time t2, and a plurality of vanes 50 are The pressure change in the exhaust passage J when controlled as described above is shown. The line β superimposed on this is conceptually an example of the pressure change in the exhaust passage J when the turbocharger 46 is allowed to start naturally without performing the operation assist of the turbocharger 46 described above. Represents. As apparent from comparing the line α and the line β in FIG. 4, the operation assist reduces the time lag of the time t <b> 1 to t <b> 3 and improves the transient response of the turbocharger 46. It becomes possible to quickly cope with the load increase.

  By the way, at this time, the angles of the plurality of vanes 50 are controlled so that the actual supercharging pressure matches the target supercharging pressure or the actual intake air amount matches the target intake air amount. Is done. For example, when the load of the turbocharger 46 becomes high, the flow passage cross-sectional area of the exhaust passage is expanded so as not to excessively increase the pressure of the exhaust passage J by controlling the opening degree of the plurality of vanes 50.

  Therefore, here, excessive pressure that is not substantially used for exhaust energy recovery by the turbine 38 is recovered in the pressure accumulating vessel 64. The exhaust gas recovery when the load on the internal combustion engine is high will be described with reference to the flowchart of FIG. However, the flowchart of FIG. 5 is repeated every predetermined time, for example, approximately every 8 ms.

  However, in the control described below with reference to FIG. 5, the output of the internal combustion engine is substantially reduced when a certain amount of output is generated by combustion of the air-fuel mixture in the internal combustion engine, that is, when power is actively generated. When the pressure in the exhaust passage J becomes equal to or higher than the pressure in the pressure accumulating vessel 64 by accelerating the pressure increase in the exhaust passage J upstream of the turbine 36 without changing the pressure, the flow control valve 66 is used. This is an example in which exhaust from the exhaust passage J to the pressure accumulating vessel 64, that is, recovery of the pressure of the exhaust is embodied. For example, the pressure of the exhaust gas thus collected in the pressure accumulating vessel 64 is the pressure of the portion surrounded by the line γ obtained by extending the line α in FIG. 4 from the time t4, and the amount thereof is the area S in FIG. It corresponds to.

  In the first embodiment, as will be apparent from the following description, the pressure increase in the exhaust passage J on the upstream side of the turbine 38 controls the opening of the throttle valve 26 so as to prevent the intake air from flowing into the cylinder 14. Prompted by a plurality of vanes 50 activated in connection with More specifically, by controlling the opening degree of the throttle valve 26 to the closed side with respect to the normal opening degree (normal opening degree) until then, the target boost pressure in the intake passage on the downstream side of the throttle valve 26 can be increased. By increasing the difference between the actual pressure in the intake passage, that is, the actual supercharging pressure, and increasing the output of the turbocharger 46 in order to improve the supercharging pressure, the exhaust gas is reduced here. Increase the pressure in passage J. In other words, by controlling the plurality of vanes 50 to the closed side, the pressure increase in the exhaust passage J is promoted. However, the throttle valve 26 is controlled to the closed side so that the supercharging pressure does not become excessively high.

  First, in step S501, it is determined whether or not the second collection flag is “1”, that is, ON. Here, the second recovery flag being “1” means that the second predetermined condition of exhaust recovery for exhaust recovery when the internal combustion engine 10 is actively generating power is satisfied. To express. On the other hand, when it is “0”, it means that the second predetermined condition is not satisfied. Since the second recovery flag is reset in the initial state, a negative determination is made here.

  If a negative determination is made in step S501, then in step S503, the pressure in the pressure accumulating container 64 (the container internal pressure in FIG. 5) is lower than the upper limit pressure in step S205 and is a predetermined pressure. It is then determined whether or not the lower limit pressure is stored in the ROM. This lower limit pressure can be determined in advance by experiments so that it can be determined whether or not exhaust gas collection into the pressure accumulating vessel 64 is necessary. The lower limit pressure may be determined in consideration of the surging limit in the compressor 44 and the overspeed limit of the turbocharger 46. The pressure in the pressure accumulating vessel 64 is obtained based on an output signal from the pressure sensor 100. However, although the lower limit pressure is used as the reference pressure for determination here, other pressure values, for example, the upper limit pressure in step S205 may be used as the reference pressure for determination in step S503.

  If an affirmative determination is made in step S503, it is then determined in step S505 whether or not the boost pressure that is the pressure in the intake passage on the downstream side of the throttle valve 26 exceeds the required maximum boost pressure that is a predetermined pressure. . This determination is a specific example of whether or not the load on the internal combustion engine 10 is high, in particular, whether or not the load on the turbocharger 46 is higher than a predetermined load. This determination is included in the determination by the required load determination means. The required maximum supercharging pressure is obtained based on the mapped data shown in FIG. FIG. 6 is a graph showing the maximum supercharging pressure with respect to the engine speed. From time to time, the necessary maximum supercharging pressure is obtained by searching the mapped data as shown in FIG. 6 at the engine speed obtained using the crank position sensor 96. Then, the determination in step S505 is performed by comparing the supercharging pressure obtained based on the output signal from the pressure sensor 88 with the necessary maximum supercharging pressure.

  If an affirmative determination is made in step S505, the second recovery flag is set to “1” in step S507, assuming that the second predetermined condition for exhaust recovery is satisfied. In step S509, the target opening (target throttle opening) for controlling the opening of the throttle valve 26 (the target throttle opening) is a base opening set based on the engine state as described above (the normal opening described above). A predetermined opening degree (closed correction throttle opening degree) that is closer to the closing side is set. Then, an actuation signal is output to the actuator 24 so that the opening degree of the throttle valve 26 matches the closing correction throttle opening degree. Such control is performed while the second collection flag is set to “1”.

  Thereby, the correction amount of the opening degree of the throttle valve 26 corrected to the closing side, that is, the offset opening degree is obtained based on the mapped data shown in FIG. The offset opening degree is obtained by searching the mapped data as shown in FIG. 7 at the engine speed at that time. FIG. 7 is a graph showing the relationship between the offset opening of the throttle valve 26 and the engine speed. However, in the graph of FIG. 7, the offset opening degree in the low rotation speed range and the high rotation speed range is set to “0” due to the surging limitation in the compressor 44 and the excessive rotation limitation of the turbocharger 46.

  Thus, the opening of the throttle valve 26 is offset to the closed side, so that the intake air is throttled more than usual, that is, the flow of the intake air flowing through the intake passage 16 so as to reach the cylinder 14 is prevented. As a result, the pressure in the intake passage on the downstream side of the throttle valve 26 decreases. In this state, the actual supercharging pressure cannot be matched with the target supercharging pressure, so that the operation of the turbocharger 46 is promoted to further increase the supercharging pressure.

  More specifically, the operation of the turbocharger 46 is promoted so as to increase the supercharging pressure while the opening of the throttle valve 26 is offset from the normal opening to the closing opening. In order to increase the rotational speed of the turbine 38, the opening degree of the plurality of vanes 50 is controlled to the opening degree on the closing side with respect to the opening degree until then at the normal time (when exhaust recovery is not performed). As a result, the flow of exhaust gas to the turbine wheel 36 is controlled, so that the rotational speed of the turbine 38 is increased. Then, as the rotational speed of the turbine 38 increases, the supercharging ability of the compressor 44 is improved, so that the supercharging pressure can be increased to the target supercharging pressure. Thus, even if the opening degree of the throttle valve 26 is different from the throttle opening degree corresponding to the target supercharging pressure as described above, the pressure in the intake passage on the downstream side of the throttle valve 26 is made to coincide with the target supercharging pressure. Is possible.

  Further, since the opening degree of the plurality of vanes 50 is controlled to the closed side so that the rotational speed of the turbine 38 increases as described above, the flow of exhaust gas reaching the exhaust passage J is blocked by the plurality of vanes 50. Thus, the pressure in the exhaust passage J can be increased. Therefore, the pressure of the exhaust passage J upstream of the turbine 38 can be increased, and the exhaust can be recovered into the pressure accumulating vessel 64 as described later. In addition, the opening degree of the several vane 50 at this time is an opening degree by the side of the predetermined amount rather than the opening degree (normal opening degree) of the vane 50 at the normal time. However, the predetermined amount can be changed each time based on the intake air amount obtained based on the output signal from the air flow meter 82 and / or the supercharging pressure obtained based on the output signal from the pressure sensor 88. This predetermined amount may be a fixed value.

  In step S501 of the routine after the next time, since the second recovery flag is “1”, an affirmative determination is made, and in next step S511, it is determined whether or not the vehicle is accelerating. This is included in determining whether or not the load on the turbocharger 46 is higher than a predetermined load. Specifically, it is determined whether or not the acceleration request is continued due to the accelerator opening being equal to or greater than a predetermined opening. Instead of such a determination, the determination in step S505 may be performed.

  If an affirmative determination is made in step S513, it is then determined in step S513 whether or not the pressure in the pressure accumulating vessel 64 is equal to or lower than the upper limit pressure in step S213. In addition, the pressure value used as a criterion here is not limited to this upper limit pressure, and may be another pressure value.

  Note that the determinations in steps S511 and S513 are performed in order to determine the end timing of exhaust recovery after the second recovery flag is set to “1” in step S507.

  If an affirmative determination is made in step S513, the same determination is made in the next step S515 for the same reason as in step S215 in FIG. Depending on the determination result in step S515, one of steps S517 and S519 corresponding to steps S217 and S219 in FIG. 2 is performed. Since the pressure in the pressure accumulating vessel 64 is equal to or lower than the pressure in the exhaust passage J, an affirmative determination is made in step S515, and the flow rate adjusting valve 66 is opened in step S519, whereby the exhaust gas is recovered in the pressure accumulating vessel 64. . This exhaust gas recovery is generally continued unless a negative determination is made in step S511 or step S513.

  If a negative determination is made in either step S511 or step S513 during exhaust gas recovery, control for terminating exhaust gas recovery is performed. If a negative determination is made in any of them, the base opening is set as the target throttle opening in the next step S521, and the opening of the throttle valve 26 becomes the base opening as described above. That is, the normal opening is controlled. Further, an operation signal is output to the actuator 68 so that the flow rate adjustment valve 66 is closed. Then, in the next step S523, the second collection flag is set to “0”, and the routine ends. As a result, the internal combustion engine 10 is returned to a normal control state in which exhaust recovery is not performed.

  As described above, when a certain output is generated by the combustion of the air-fuel mixture, especially when the load of the turbocharger 46 is high, the throttle valve 26 is closed to prevent the intake air from flowing into the cylinder 14. By controlling, the opening degree of the plurality of vanes 50 is controlled to the closing side. Therefore, the pressure in the exhaust passage J upstream of the turbine 38 can be increased, and the exhaust gas can be recovered in the pressure accumulating vessel 64. Therefore, for example, after the exhaust gas in the pressure accumulating vessel 64 is used for the turbocharger 46, the exhaust gas can be recovered and filled in the accumulator vessel 64 (see FIG. 4). It becomes possible to increase. That is, when the plurality of vanes 50 can be driven closer to the closing side, the throttle valve 26 is controlled to the closing side, thereby controlling the plurality of vanes 50 to the closing side and the exhaust passage on the upstream side of the turbine 38. It becomes possible to raise the pressure of J, and it becomes possible to collect | recover exhaust_gas | exhaustion in the pressure accumulation container 64. FIG.

  Note that the determination criterion in step S505 may not be the necessary maximum supercharging pressure. Other criteria that allow determining that the load of the internal combustion engine is higher than the predetermined load may be used, and the predetermined load may be various loads. In step S505, the determination is made based on the pressure in the intake passage on the downstream side of the compressor 44. However, the determination may be made based on the intake air amount. When the determination is performed based on the intake air amount, a necessary maximum intake air amount or various intake air amounts can be used as a determination criterion. The required maximum intake air amount may be obtained each time by searching the mapped data (not shown) by the engine speed.

  In the first embodiment, in the exhaust gas recovery control based on the flowchart in FIG. 5, the VN opening is set so that the actual boost pressure, that is, the intake pressure downstream of the throttle valve 26 matches the target boost pressure. It was adjusted. However, as can be understood from the above description, the VN opening may be adjusted so that the target intake air amount matches the actual intake air amount and the intake air amount obtained using the air flow meter 82.

  In the first embodiment, the exhaust gas is collected in the pressure accumulator 64 based on the flowchart of FIG. 2 even during fuel cut, except when the load on the turbocharger 46 is high. However, such exhaust recovery during fuel cut may not be performed. In this case, the exhaust throttle valve 70 can be omitted.

  In the first embodiment, the turbocharger 46 is a variable nozzle turbocharger. However, other types of turbochargers may be used. For example, the turbocharger 46 may be a turbocharger provided with a wastegate valve. This case will be described below as a second embodiment.

  The internal combustion engine system of the second embodiment is different from that of the first embodiment described above in that an exhaust passage K on the upstream side of the turbine wheel 36 and an exhaust gas on the downstream side of the turbine wheel 36 are used instead of providing a plurality of vanes 50 in the turbocharger 46. Except for the fact that a wastegate valve is provided in a bypass passage that bypasses the turbine wheel 36 so as to connect the passage, and there is an actuator that is controlled by the ECU 80 for driving the wastegate valve, it is substantially the same. Therefore, the illustration of the internal combustion engine system of the second embodiment is omitted here, the same reference numerals are given to the same components as those described in the first embodiment, and the description of those components is omitted. To do. However, in the second embodiment, the exhaust flow control means includes a waste gate valve and a waste gate valve control means including a part of the ECU 80 and the actuator for controlling the waste gate valve.

  In the second embodiment as well, the exhaust gas recovery control based on the flowcharts of FIGS. 2 and 5 is performed as in the first embodiment. Similarly, exhaust use control based on the flowchart of FIG. 3 is performed. Exhaust recovery control when the internal combustion engine 10 is actively generating power according to the second embodiment is performed based on the flowchart of FIG. 5, but the closed corrected throttle opening is set as the target throttle opening. This is different from that of the first embodiment in that the object to be controlled to achieve the target boost pressure is the wastegate valve. Only this point will be described below. However, the second embodiment also has the same effect as that of the first embodiment, and the same change as that of the first embodiment is allowed.

  In order to bypass the turbine wheel 36 of the turbocharger 46, a waste gate valve is provided in a bypass passage that connects the exhaust passage upstream of the turbine wheel 36 and the exhaust passage downstream of the turbine wheel 36 and upstream of the catalytic converter 34. ing. The wastegate valve is normally controlled by an actuator operated by the ECU 80 so that exhaust gas other than the necessary amount is not supplied to the turbine 38 when exhaust recovery based on the flowchart of FIG. 5 is not performed. Specifically, when the supercharging pressure exceeds a predetermined pressure or when the intake air amount exceeds a predetermined flow rate, the wastegate valve that has been closed until then is opened. That is, the wastegate valve is normally opened when the supercharging pressure exceeds the required maximum supercharging pressure.

  On the other hand, when the exhaust pressure can be recovered in the pressure accumulating vessel 64 (affirmative determination in step S503) and the supercharging pressure exceeds the necessary maximum supercharging pressure (positive determination in step S505). The waste gate valve is thus closed to a closing correction opening degree that is a predetermined opening degree on the closing side with respect to the opening degree (normal opening degree) that is normally open. In this way, even if the throttle valve 26 is closed to a close correction throttle opening degree that is a certain degree of opening degree (see step S509 above), the operation of the turbocharger 46 is promoted to achieve the target supercharging pressure. Is possible. In addition to this, the pressure of the exhaust passage J can be sufficiently increased by controlling the wastegate valve to an opening closer to the closing side than the normal opening. Therefore, it becomes possible to collect the exhaust gas into the pressure accumulating vessel 64 as described above.

  Specifically, since the second recovery flag is set to “1”, the opening degree of the waste gate valve is corrected from the normal opening degree to the closing side while the throttle opening degree is set to the closing correction throttle opening degree. The predetermined opening of the minute, that is, the offset opening, is preferably set each time based on the mapped data as shown in FIG. The offset opening degree of the wastegate valve is obtained by searching FIG. 8 based on the engine speed. Note that the mapped data in FIG. 8 showing the relationship between the offset opening and the engine speed is determined in consideration of the surging limit in the compressor 44 and the overspeed limit of the turbocharger 46.

  Next, a third embodiment of the present invention will be described. The vehicle internal combustion engine system to which the third embodiment is applied differs from the internal combustion engine system of the first embodiment in terms of a turbocharger. However, since the internal combustion engine system of both embodiments is substantially the same in other points, the difference in configuration will be described below, and the difference in control caused by the difference in configuration will be described below. To do. In the following description, components that are substantially the same as those already described above are denoted by the same reference numerals, and description thereof is omitted. However, the third embodiment also has the same effects as the first and second embodiments, and the same changes as the first and second embodiments are allowed.

  The turbocharger 46 of the third embodiment is a multistage turbocharger, as is apparent from FIG. 9 schematically showing the relationship between the components of the internal combustion engine system with some components omitted. . Here, the multi-stage turbocharger includes two turbochargers, that is, a low-pressure stage turbocharger 46A and a high-pressure stage turbocharger 46B. However, the present invention allows more than two turbochargers to be included.

  The intake passage between the air cleaner 22 and the intercooler 48 is provided with a compressor 44A of the low-pressure stage turbocharger 46A and a compressor 44B of the high-pressure stage turbocharger 46B positioned in the intake passage on the downstream side of this. Yes. A compressor bypass valve 44Bv is provided in a bypass passage provided so as to bypass the compressor wheel of the compressor 44B. The compressor bypass valve 44Bv is driven by an actuator 44Ba controlled by the ECU 80.

  On the other hand, in the exhaust passage between the engine body 10a and the catalytic converter 34, there are a turbine 38A of the low-pressure stage turbocharger 46A and a turbine 38B of the high-pressure stage turbocharger 46B positioned in the exhaust passage upstream of this. Is provided. A turbine bypass valve 38Bv is provided in a bypass passage provided to bypass the turbine wheel of the turbine 38B. The turbine bypass valve 38Bv is driven by an actuator 38Ba controlled by the ECU 80. The compressor 44A and the turbine 38A are coaxially connected via a rotating shaft 40A, and the compressor 44B and the turbine 38B are coaxially connected via a rotating shaft 40B.

  And the pressure accumulation container 64 is made to communicate with the exhaust passage J also in the third embodiment. However, in the third embodiment, the exhaust passage J is an exhaust passage on the upstream side of the turbine 38B of the high-pressure stage turbocharger 46B.

  When only supercharging by the low-pressure stage turbocharger 46A is sufficient, the compressor bypass valve 44Bv and the turbine bypass valve 38Bv are normally opened. When the supercharging by the low-pressure stage turbocharger 46A is not sufficient, that is, when the supercharging by the high-pressure stage turbocharger 46B is required to further increase the supercharging pressure, the compressor bypass valve 44Bv is normally closed. The turbine bypass valve 38Bv is also closed. On the other hand, when the load of the turbocharger 46 is high, for example, when the supercharging pressure by the low-pressure stage and high-pressure stage turbochargers 46A and 46B exceeds the necessary maximum supercharging pressure, the compressor bypass valve 44Bv is usually also a turbine bypass valve. 38Bv can also be opened.

  On the other hand, in the third embodiment as well, the exhaust gas recovery control based on the flowcharts of FIGS. 2 and 5 is performed as in the first embodiment. Similarly, exhaust use control based on the flowchart of FIG. 3 is performed. The exhaust recovery control when the load of the internal combustion engine 10 is high according to the third embodiment is performed based on the flowchart of FIG. 5, but when the closed correction throttle opening is set as the target throttle opening, It differs from that of the first embodiment in that the object to be controlled to achieve the supply pressure is the compressor bypass valve 44Bv and / or the turbine bypass valve 38Bv. Only this point will be described below. In the third embodiment, the exhaust flow control means includes the turbine bypass valve 38Bv and the control means including a part of the actuator 38Ba and the ECU 80.

  When there is a margin in the pressure accumulating vessel 64 so that exhaust gas can be recovered (affirmative determination in step S503), and when the supercharging pressure exceeds the required maximum supercharging pressure (positive determination in step S505), the compressor bypass valve 44Bv and / or the turbine bypass valve 38Bv are thus closed to a closing correction opening that is a predetermined opening on the closing side with respect to the opening that is normally open (normal opening). By doing so, even if the throttle valve 26 is closed to a closed correction throttle opening degree that is a certain degree of opening degree (see step S509), the operation of the turbocharger 46B is promoted to achieve the target supercharging pressure. Is possible. As a result, the pressure in the exhaust passage J can be sufficiently increased. Therefore, it becomes possible to collect the exhaust gas into the pressure accumulating vessel 64 as described above.

  Specifically, since the second recovery flag is set to “1”, the opening degree of the turbine bypass valve 38Bv is corrected from the normal opening degree to the closing side while the throttle opening degree is set to the closing correction throttle opening degree. The predetermined opening, that is, the offset opening, is preferably set each time based on the mapped data as shown in FIG. 8 with the vertical axis replaced with the offset opening of the turbine bypass valve 38Bv. The offset opening degree of the opening degree of the turbine bypass valve 38Bv is obtained by searching this data based on the engine speed. The data is determined in consideration of the surging limit in the compressor and the over-rotation limit of the turbocharger.

  Next, a fourth embodiment of the present invention will be described. In the fourth embodiment, while the second recovery flag is set to “1” with each of the first to third embodiments, the target to be corrected to the closing side is not the throttle valve 26 but the swirl control valve. (SCV) is different. However, the vehicle internal combustion engine system to which the fourth embodiment is applied is substantially the same as that described in the first to third embodiments except that the SCV is provided in the intake passage of each cylinder 14. is there. Therefore, only the difference in configuration and the difference in control based on this will be described below. In the following description, components that are substantially the same as those already described above are denoted by the same reference numerals, and description thereof is omitted. However, the fourth embodiment also has the same effects as those of the first, second, and third embodiments, and the same changes as those of the first, second, and third embodiments are allowed. However, in the present fourth embodiment, the intake flow control means includes SCV and SCV control means including an SCV control actuator and a part of the ECU 80.

  In the vehicle internal combustion engine system to which the fourth embodiment is applied, though not shown, two intake passages are connected to each cylinder 14 and one of them is provided with an SCV. . Here, the intake passage defined by the intake manifold 18 for each cylinder 14 is divided into two, and the SCV is provided in the intake manifold 18 so that one of them can be opened and closed. The SCV is driven by an actuator controlled by the ECU 80 so that it normally has an opening (normal opening) set based on the engine state. Specifically, the SCV is closed so as to increase the swirl in the cylinder 14 when the engine speed is in the low speed range. On the other hand, the SCV is opened when the engine rotation speed belongs to the high rotation range.

  When there is a margin in the pressure accumulating vessel 64 so that the exhaust can be recovered (affirmative determination in step S503), and when the intake air amount exceeds the maximum air amount (affirmative determination in step replaced with step S505), As a target opening (target SCV opening) of the SCV opening, a predetermined opening (closed corrected SCV opening) closer to the closing than the normal opening (normal opening) is set (step S509). Equivalent). Then, an actuation signal is output to the actuator so that the SCV opening coincides with the closing correction SCV opening. Such control is performed while the second collection flag is set to “1”.

  The correction amount from the normal opening to the closing side of the SCV opening at this time, that is, the offset opening, is based on the mapped data as shown in FIG. 7 in which the vertical axis is replaced with the SCV offset opening. Desired. In other words, the offset opening of the SCV can be obtained by searching the data with the engine speed at that time. The data is determined in consideration of a surging limit in the compressor 44 and an overspeed limit of the turbocharger 46.

  By doing so, the flow of intake air from the intake passage 16 into the cylinder 14 is hindered, and the operation of the turbocharger 46 is urged so as to achieve the target intake air amount. The acceleration of the operation of the turbocharger 46 can be achieved by controlling the opening degree of the plurality of vanes 50 to the closed side according to the configuration of the turbocharger 46, as described in the first to third embodiments, This can be achieved by controlling the opening of the valve to the closed side or controlling the opening of the turbine bypass valve 38Bv to the closed side.

  Next, a fifth embodiment of the present invention will be described. In the fifth embodiment, each of the above first to third embodiments and the target that works to prevent the flow of intake air flowing through the intake passage 16 while the second recovery flag is set to “1” are the intake valves. It is different in that. However, since the internal combustion engine system of the vehicle to which the fifth embodiment is applied is substantially the same as that described in the first to third embodiments, only the difference in control based thereon will be described below. To do. In the following description, components that are substantially the same as those already described above are denoted by the same reference numerals, and description thereof is omitted. However, the fifth embodiment also has the same effect as the first to fourth embodiments, and the same changes as the first to fourth embodiments are allowed. In the fifth embodiment, the intake flow control means includes an intake valve and a variable valve mechanism for driving the intake valve that includes a part of the ECU 80.

  In the vehicle internal combustion engine system to which the fifth embodiment is applied, the closing timing of the intake valve is set to a normal time, a time when the bottom dead center is passed (normally closing time), for example, 30 ° to 45 ° after the bottom dead center. Has been.

  When there is a margin in the pressure accumulating vessel 64 so that the exhaust can be recovered (affirmative determination in step S503), and when the intake air amount exceeds the maximum air amount (affirmative determination in step replaced with step S505), As a closing timing of the intake valve, a predetermined timing (retarding correction timing) that is retarded from the normal closing timing is set. Then, the valve mechanism is controlled so that the intake valve is closed at the retard correction timing. Such control is performed while the second collection flag is set to “1”.

  The offset phase toward the retard side of the intake valve closing timing at this time is obtained based on the mapped data as shown in FIG. 7 in which the vertical axis is replaced with the offset phase of the intake valve. However, the data is determined so that the amount of retardation increases as it goes upward in the figure. The offset phase of the intake valve is obtained by searching the data with the engine speed at that time. The data is determined in consideration of a surging limit in the compressor 44 and an overspeed limit of the turbocharger 46.

  By doing so, the flow of intake air from the intake passage 16 into the cylinder 14, that is, the intake, is hindered, so that the operation of the turbocharger 46 is promoted so as to achieve the target intake air amount. The acceleration of the operation of the turbocharger 46 can be achieved by controlling the opening degree of the plurality of vanes 50 to the closed side according to the configuration of the turbocharger 46, as described in the first to third embodiments, This can be achieved by controlling the opening of the valve to the closed side or controlling the opening of the turbine bypass valve 38Bv to the closed side.

  In the fifth embodiment, when the exhaust gas is collected into the pressure accumulating vessel 64, the closing timing of the intake valve is offset to the retard side. For example, the intake valve is closed to reduce the intake efficiency. The time may be offset toward the advance side. In addition, in the present invention, it is allowed to change at least one of the valve timing and the lift amount of the intake valve so as to reduce the intake efficiency.

  Next, reference examples related to the present invention will be described. In the first to fifth embodiments, the intake air flow control means hinders the flow of intake air into the cylinder 14, thereby promoting the operation of the turbocharger 46 and enabling exhaust gas recovery. However, other means can be used to promote the operation of the turbocharger 46 and to enable exhaust gas recovery. As the means, there is an intake flow target value variable means for changing a target value for controlling the flow of intake air in the intake passage.

  For example, the intake flow target value variable means changes the throttle opening to the closed correction throttle opening that is the target throttle opening in the first embodiment, but instead, increases the target boost pressure or sets the target intake pressure. Increase the amount of air. The case where the target boost pressure is increased will be described below. However, the configuration of the internal combustion engine system of the vehicle in the case of this reference example is substantially the same as that of the first embodiment. And also in the case of this reference example, control based on the flowchart of FIG. 2, FIG. 3 may be performed similarly to the case of the said 1st Embodiment. However, this reference example is different from the first embodiment in terms of exhaust recovery control based on the flowchart of FIG. Therefore, hereinafter, the same components as those described above are denoted by the same reference numerals, and the description thereof will be omitted, but only the differences will be described.

  In this reference example, there is a margin in the pressure accumulating vessel 64 so that exhaust gas can be recovered (affirmative determination in step S503), and when the supercharging pressure exceeds the required maximum supercharging pressure (determined positive in step S505). Then, the preset supercharging pressure (base supercharging pressure) including the necessary maximum supercharging pressure used in step S505 is increased by a predetermined amount. This predetermined amount is appropriately obtained by searching the mapped data of FIG. 10 representing the relationship between the offset pressure of the target supercharging pressure and the engine speed by the engine speed. Then, the predetermined amount is added to the base supercharging pressure to obtain an increased correction supercharging pressure, which is set as the target supercharging pressure.

  Since the increased correction supercharging pressure is set as the target supercharging pressure, the operation of the turbocharger 46 is promoted by controlling the plurality of vanes 50 to the closed side so as to realize the increased supercharging pressure. Therefore, as described above, the pressure in the exhaust passage J upstream of the turbine 38 is increased, and the exhaust can be recovered.

  As mentioned above, although 5 embodiment which concerns on this invention, those modifications, and the reference example were demonstrated, this invention is not limited to these. The present invention allows the first to fifth embodiments and the modifications thereof, as well as the mutual combination of the reference examples and other partial combinations thereof.

  In the above-described five embodiments and their modifications, in the exhaust gas recovery control based on the flowchart in FIG. 5, the target boost pressure is set downstream of the actual throttle valve 26 with respect to the intake air flow control that throttles the intake air into the cylinder. The VN opening, the opening of the wastegate valve, etc. are adjusted so that the supercharging pressure on the side matches, or the intake air amount obtained using the actual air flow meter 82 matches the target intake air amount did. However, the VN opening degree, the opening degree of the wastegate valve, and the like may be adjusted so that the actual supercharging pressure coincides with the target supercharging pressure and the actual intake air quantity coincides with the target intake air quantity.

  Further, in the above-described five embodiments, when accelerating or accelerating, the gas in the pressure accumulating vessel is supplied to the exhaust passage upstream of the turbine wheel or the exhaust gas is recovered from the exhaust passage. The time when the use and recovery of various gases is not limited to acceleration. They can be done if the demand load on the internal combustion engine is increased or when the internal combustion engine is actively generating power. When the required load on the internal combustion engine increases, it includes when accelerating and when the required load on the internal combustion engine increases, such as when the load increases as the vehicle faces an uphill. In this specification, “load” in the expressions “required load” and “load” includes the concepts of “torque” and “output”. Further, when power is actively generated in the internal combustion engine, for example, the VN opening degree, the opening degree of the wastegate valve, and the like may be when there is a margin that can be adjusted to the closed side.

  In the above five embodiments, various types of valves are used. However, the present invention is not limited to these, and other types of valves can be used as these valves. For example, the exhaust throttle valve may be a poppet type valve or a shutter type valve. A valve provided for the exhaust brake may be used as the exhaust throttle valve. The actuators that drive the various valves described above can be various types of actuators such as electric motors and negative pressure actuators. In addition, when the pipe line 62 is provided only for the gas collection | recovery in the pressure accumulation container 64, the valve provided there may be a check valve.

  In the above five embodiments, one pressure accumulating container 64 is provided, but a plurality of pressure accumulating containers 64 may be provided. When two or more accumulator containers 64 are provided, the accumulator containers 64 can be dispersed in the vehicle.

  In the above five embodiments, the present invention is applied to a diesel engine. However, the present invention is not limited to this, and the present invention can be applied to various types such as a port injection type gasoline engine and a cylinder injection type gasoline engine. Applicable to internal combustion engines. The fuel used is not limited to light oil or gasoline, but may be alcohol fuel, LPG (liquefied natural gas), or the like. Further, the number of cylinders of the internal combustion engine to which the present invention is applied may be any number.

  Although the present invention has been described with a certain degree of specificity in the above five embodiments and modifications thereof, the present invention can be variously modified without departing from the spirit and scope of the invention described in the claims. It should be understood that various modifications and changes are possible. That is, the present invention includes modifications and changes that fall within the scope and spirit of the appended claims and their equivalents.

1 is a conceptual diagram of an internal combustion engine system for a vehicle to which a first embodiment is applied. It is a control flowchart for exhaust gas collection at the time of fuel cut of the first embodiment. It is a control flowchart for exhaust emission of a 1st embodiment. FIG. 6 is a schematic graph showing a change in the exhaust passage pressure during control based on the flowchart of FIG. 3 with respect to time and an increasing tendency of the exhaust passage pressure by the control based on the flowchart of FIG. 5. It is a control flowchart for exhaust gas recovery when the load of the internal combustion engine is high according to the first embodiment. It is the graph which represented typically the example of a relationship between required maximum supercharging pressure and engine speed. 6 is a graph schematically showing the relationship between the throttle valve offset opening and the engine speed used in the exhaust gas recovery control based on the flowchart of FIG. In 2nd Embodiment, it is the graph which represented typically the relationship between the offset opening degree of a wastegate valve, and engine speed used by control for exhaust_gas | exhaustion collection | recovery when the load of an internal combustion engine is high. It is the figure which represented typically the relationship between the one part components of the internal combustion engine system of the vehicle to which 3rd Embodiment was applied. In the reference example of the present invention, it is a graph schematically showing the relationship between the offset pressure of the target supercharging pressure and the engine rotation speed used in the control for exhaust gas recovery when the load on the internal combustion engine is high.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Internal combustion engine 10a Engine main body 26 Throttle valve 36 Turbine wheel 38 Turbine 42 Compressor wheel 44 Compressor 46 Turbocharger 50 Vane 64 Accumulation container 66 Flow control valve 70 Exhaust throttle valve

Claims (4)

In an internal combustion engine with a turbocharger including a turbine provided in an exhaust passage and a compressor connected to the turbine and provided in an intake passage,
A pressure accumulating vessel capable of communicating with an exhaust passage upstream of the turbine;
Exhaust flow control means for controlling the flow of exhaust to the turbine wheel of the turbine;
Intake flow control means for controlling the flow of intake air into the cylinders of the internal combustion engine, wherein the intake air is throttled when exhaust recovery is performed in the pressure accumulating vessel compared to when the exhaust recovery is not performed. An internal combustion engine with a turbocharger, comprising:   2. The exhaust gas flow control means according to claim 1, wherein when the exhaust gas is collected in the pressure accumulating vessel, the rotation speed of the turbine is higher than when the exhaust gas is not collected. An internal combustion engine with a turbocharger. The intake flow control means includes any one of an intake throttle valve and a swirl control valve, and valve control means for controlling any one of the valves,
When the exhaust gas is collected in the pressure accumulating vessel, the valve control means controls the opening degree of either one of the valves so that the opening degree is closer to the closing degree than the opening degree when the exhaust gas collection is not performed. The turbocharged internal combustion engine according to claim 1 or 2, characterized in that The intake flow control means includes a variable valve mechanism that varies at least one of valve timing and lift amount of the intake valve,
The variable valve mechanism is configured to collect at least one of the valve timing and the lift amount of the intake valve so that the intake efficiency is lower than the intake efficiency when the exhaust recovery is not performed when the exhaust recovery is performed in the pressure accumulating vessel. The internal combustion engine with a turbocharger according to any one of claims 1 to 3, wherein

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