JP2006105026A - Supercharging controller for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a supercharging controller for an internal combustion engine capable of improving acceleration performance by promptly starting up supercharging pressure at the time of accelerating from a low load state. <P>SOLUTION: The supercharging controller for an internal combustion engine controls a variable nozzle turbocharger 12 comprising a turbine rotor 16 provided at an exhaust passage of an engine 1, a variable vane 18 opening and closing to make flow velocity of exhaust gas for driving the turbine rotor 16 variable, and a compressor 13 provided at an intake passage for supplying air to the engine according to driving torque of the turbine rotor 16. The supercharging controller is characterized by comprising an acceleration request determining means for determining presence/absence of an acceleration request by a driver, an assisting means for assisting the drive of the turbine rotor 16, and a control means for operating the assisting means when the acceleration request determining means determines the acceleration request by a driver to be present. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a supercharging control device for an internal combustion engine that controls a variable nozzle turbocharger that can change a supercharging pressure by adjusting the opening of a variable member in accordance with the operating state of the internal combustion engine (hereinafter referred to as an engine). .

  In recent years, an engine equipped with a variable nozzle turbocharger has been put into practical use in order to improve torque over the entire range from low speed to high speed. This type of variable nozzle turbocharger is configured so that the gas inflow speed to the turbine rotor can be changed by a variable member such as a movable vane, and the variable member is controlled in accordance with the operating state of the engine to supercharge in a wide rotation range. The engine torque is improved by adjusting the pressure appropriately.

For example, when accelerating the vehicle from a low load state, such as when starting the vehicle from idle stop or accelerating during low-speed driving, the variable member is controlled to the closed side and the boost pressure is controlled. By increasing the engine torque, the engine torque is increased to accelerate the vehicle quickly (Patent Document 1).
Japanese Utility Model Publication 4-33384

  In an engine equipped with a variable nozzle turbocharger as described above, the supercharging pressure can be adjusted appropriately by controlling the variable member after the acceleration is started, but at the moment of starting the acceleration from a low load state, the supercharging is performed. A phenomenon that the rise of pressure is delayed occurs.

  More specifically, since the engine torque is not so much required during idling and low load conditions such as low speed running, the variable member is controlled to the open side and is kept in a substantially non-supercharged state. When the driver depresses the accelerator from this state, first, the variable member is controlled to the closed side, and the exhaust pressure increases. Next, the engine torque increases after taking the step of boosting the boost pressure with the turbine rotor speed and increasing the volumetric efficiency, and then controlling the fuel injection amount in the increasing direction. Therefore, there is a problem that sufficient acceleration performance cannot be obtained immediately after the accelerator is depressed by the driver.

  The present invention has been made in view of such problems of the prior art. For example, a supercharging control for an internal combustion engine that can quickly increase a supercharging pressure and improve acceleration performance even when accelerating from a low load state. An object is to provide an apparatus.

  In order to achieve the above object, a supercharging control device for an internal combustion engine according to claim 1 is opened and closed to make the flow rate of exhaust gas for driving the turbine rotor and the turbine rotor provided in the exhaust path of the internal combustion engine variable. In a supercharging control device for an internal combustion engine that controls a variable nozzle turbocharger that has a variable vane that operates and a compressor that is provided in an intake passage and supplies air to the internal combustion engine in accordance with a driving torque of a turbine rotor, An acceleration request determining means for determining the presence or absence of an acceleration request; an auxiliary means for assisting the rotational drive of the turbine rotor; and a control means for operating the auxiliary means when the acceleration request determining means determines that the driver has requested acceleration. It is characterized by providing.

  According to this, the auxiliary means for assisting the rotational drive of the turbine rotor is provided in the engine, and the control means operates the auxiliary means when the acceleration request determining means determines the driver's acceleration request. The pressure can be quickly raised, and sufficient acceleration performance can be obtained.

  The auxiliary means of the supercharging control device for an internal combustion engine according to claim 2 is a positive pressure supply means for supplying a positive pressure exceeding a pressure generated by the flow of exhaust gas to the exhaust passage.

  According to this, since the positive pressure supply means for supplying the positive pressure exceeding the pressure generated by the circulation of the exhaust gas to the exhaust path is provided to assist the rotational drive of the turbine rotor, the turbine rotor, the compressor rotor, and The rotational drive of the turbine rotor can be assisted without adding a device for assisting the rotational drive to the turbo rotating shaft.

  The positive pressure supply means of the supercharging control device for an internal combustion engine according to claim 3 is connected to the air compressor for generating a positive pressure, an air tank for accumulating the positive pressure generated by the air compressor, and an ejection port. Consists of a nozzle part directed to the turbine rotor and a control valve for controlling the supply of positive pressure ejected from the nozzle part.

  According to this, since the positive pressure with a high flow velocity is directly ejected toward the turbine rotor, the rotational drive of the turbine rotor can be assisted with good response.

  The air compressor and the air tank of the supercharging control device for an internal combustion engine according to claim 4 are an air compressor and an air tank used for a booster device for a foot brake mounted on a vehicle on which the internal combustion engine is mounted. Features.

  In general, a booster for a foot brake using a compressed air as a boosting source is mounted on a commercial vehicle such as a truck having a relatively large load. The foot brake booster includes an air compressor that generates compressed air that serves as a boost source, and an air tank that stores the compressed air.

  According to this, since the air compressor and the air tank are used as part of the components of the positive pressure supply means of the present invention, the air compressor and the air tank can be shared.

  The supercharging control device for an internal combustion engine according to claim 5 includes a pressure sensor for measuring the pressure in the air tank, and the control means opens the control valve when the pressure sensor detects a pressure equal to or lower than the first pressure. It has the prohibition means which prohibits.

  According to this, since the control means has the prohibition means for prohibiting the opening of the control valve when the pressure sensor detects a pressure equal to or lower than the first pressure, the positive pressure in the air tank is changed to another positive pressure. Can be supplied to devices that require

  The supercharging control device for an internal combustion engine according to claim 6 is provided with auxiliary positive pressure generating means that is operated by hydraulic pressure, generates positive pressure, and supplies positive pressure to the auxiliary means. It has an auxiliary positive pressure control means for operating the auxiliary positive pressure generating means when a pressure not lower than the first pressure and lower than the second pressure is detected.

  According to this, since the control means has the auxiliary positive pressure control means for operating the auxiliary positive pressure generating means when the pressure sensor detects the pressure not lower than the first pressure and not higher than the second pressure. The auxiliary positive pressure generating means can be controlled in accordance with the pressure state in the air tank.

  The first pressure described in claim 7 is a pressure value that ensures the operation of the foot brake by the booster.

  According to this, since the first pressure is set to a pressure value that ensures the operation of the foot brake by the booster, when the pressure sensor detects a pressure equal to or lower than the first pressure, the control valve is prohibited from being opened, and the pressure is doubled. The pressure of the compressed air supplied to the force device can be ensured, and the vehicle can be driven safely.

  The second pressure according to claim 8 is a pressure value required to cause the turbine rotor to be rotationally driven by the pressure generated by the flow of the exhaust gas and to generate a rotational drive exceeding the rotational drive. .

  According to this, since the second pressure is set to a pressure value necessary to cause the turbine rotor to be rotationally driven by the pressure generated by the flow of the exhaust gas and to exceed the rotational drive, the pressure in the air tank is When the pressure is equal to or higher than the first pressure and equal to or lower than the second pressure, the positive pressure in the air tank determines that the turbine rotor cannot be rotationally driven, and the control means operates the auxiliary positive pressure generation means. The rotational drive of the turbine rotor can be assisted by the positive pressure generated by the auxiliary positive pressure generating means.

  The auxiliary means of the supercharging control device for an internal combustion engine according to claim 9 is characterized in that a positive pressure is supplied for a predetermined time determined according to the operating state of the internal combustion engine.

  The pressure of the exhaust system varies depending on the operating state of the internal combustion engine. When the pressure of the exhaust system changes, the pressure applied to the turbine rotor also changes. In some cases, even if the opening of the nozzle is controlled, the turbine rotor may not be driven to rotate appropriately. In contrast, according to the ninth aspect of the present invention, since the time for supplying the positive pressure is changed according to the operating state of the internal combustion engine, the rotational drive of the turbine rotor can be made appropriate.

  Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is an overall configuration diagram of an internal combustion engine according to an embodiment of the present invention.

  The engine 1 described in the present embodiment is a multi-cylinder engine, but only one cylinder is shown in FIG. 1 as a sectional view. The engine 1 includes a fuel injection valve 7 attached so that its injection hole faces the combustion chamber of each cylinder. Further, an intake branch pipe 3 is connected to the engine 1, and each branch pipe of the intake branch pipe 3 communicates with a combustion chamber of each cylinder. The intake branch pipe 3 is connected to the intake pipe 4. The intake pipe 4 is connected to an air cleaner box (not shown). An intake duct (not shown) for taking fresh air into the air cleaner box is connected to the air cleaner.

  A compressor 13 of a variable nozzle turbocharger 12 is provided in the intake pipe 4 downstream of the air cleaner. A compressor rotor 14 is provided in the compressor 13 for compressing fresh air drawn from the intake duct to a predetermined pressure. An intercooler 9 is disposed in the intake pipe 4 downstream of the compressor 13, and an intake throttle valve 8 is provided in the intake pipe 4 downstream of the intercooler 9.

  On the other hand, an exhaust branch pipe 5 is connected to the engine 1, and each branch pipe of the exhaust branch pipe 5 communicates with a combustion chamber of each cylinder. The exhaust branch pipe 5 is connected to the exhaust pipe 6 via the turbine 15 of the variable nozzle turbocharger 12. A turbine rotor 16 is provided in the turbine 15. The turbine rotor 16 is connected to the compressor rotor 14 via a turbo rotating shaft 17.

  A number of vanes 18 are provided around the turbine rotor 16 so as to surround the turbine rotor 16. The opening degree of these vanes 18 is simultaneously changed by a vane adjusting actuator 20 via a rod 19 (illustration of the connection state between the vane 18 and the rod 19 is omitted). The flow rate of the exhaust gas introduced into the turbine rotor 16 is increased by adjusting the vane 18 to the closed side, and the flow rate of the exhaust gas introduced into the turbine rotor 16 is decreased by adjusting the vane 18 to the open side. An exhaust gas purification catalyst (not shown) for purifying toxic gas components in the exhaust gas is provided in the middle of the exhaust pipe 6.

  In the engine 1 configured as described above, fresh air sucked from the intake duct is introduced into the compressor 13 after dust and dust are removed by the air cleaner box. The fresh air compressed by the compressor 13 is cooled by the intercooler 9 and then supplied to the combustion chamber of each cylinder via the intake branch pipe 3.

  The fresh air supplied to the combustion chamber of each cylinder is compressed in the compression stroke, and the fuel injected from the fuel injection valve 7 is burned and exploded in the latter half of the compression stroke, and the piston 2 is lowered by the combustion force and the explosion force. Then, an engine output shaft (crankshaft) (not shown) is rotated.

  Burned gas (hereinafter referred to as exhaust gas) burned and exploded in the combustion chamber of each cylinder is discharged from the combustion chamber to the exhaust branch pipe 5 in the exhaust stroke. The exhaust gas discharged to the exhaust branch pipe 5 is adjusted in flow rate by the vane 18 and rotated to the exhaust pipe 6 after rotating the turbine rotor 16. For example, when the vehicle accelerates, the vane adjustment actuator 20 is driven, the vane 18 is adjusted to the closed side, the exhaust gas flow rate is increased, and the rotational speed of the turbine rotor 16 is increased. Thereafter, the exhaust gas is discharged into the atmosphere after the harmful gas components in the exhaust gas are purified by the exhaust gas purification catalyst.

  The engine 1 is provided with an exhaust gas recirculation (EGR) mechanism. The EGR mechanism includes an EGR passage 21 that connects the exhaust branch pipe 5 and the intake branch pipe 3, a flow rate control valve (hereinafter referred to as an EGR valve) 22 that adjusts an exhaust gas recirculation amount in the EGR passage 21, and an EGR passage 21. It is comprised from the EGR cooler 23 which cools the exhaust gas which flows through.

  In the EGR mechanism configured as described above, when the EGR valve 22 is opened, part of the exhaust gas discharged from each cylinder flows to the intake branch pipe 3 via the EGR passage 21 and flows from the upstream of the intake system. The fresh air is supplied to the combustion chamber of each cylinder.

  At this time, the amount of fresh air in the combustion chamber decreases by the amount of exhaust gas recirculated to the intake system. The amount of fresh air supplied into the combustion chamber can be adjusted by adjusting the valve opening amount of the EGR valve 22. Further, by performing the above-described waste recirculation, the inert gas component in the exhaust gas is supplied into the combustion chamber, so that the combustion temperature of the air-fuel mixture is lowered and the amount of NOx and other emissions is reduced. It becomes possible.

  The exhaust system of the engine 1 is provided with a positive pressure supply device 24 as auxiliary means for assisting the rotational drive of the turbine rotor 16. The positive pressure supply device 24 includes an air compressor 25, an air tank 26, a positive pressure control valve 27, and an auxiliary positive pressure generation device 28, and a positive pressure exceeding the pressure generated by the exhaust gas flow in the exhaust system of the engine 1. (Hereinafter, referred to as compressed air) is supplied to assist the rotational drive of the turbine rotor 16.

  The air compressor 25 is connected to the output shaft of the electric motor or engine and generates compressed air. The compressed air generated by the air compressor 25 is accumulated in the air tank 26. A pressure sensor 29 for monitoring the pressure of compressed air is provided in the air tank 26.

  A nozzle 31 is connected to the air tank 26 via a pipe 30. The nozzle 31 is provided in the turbine 15, and the outlet of the nozzle 31 is directed to the turbine rotor 16. The turbine rotor 16 is driven to rotate by compressed air ejected from the nozzle 31. By making the diameter of the outlet of the nozzle 31 smaller than the diameter of the pipe 30, the flow velocity of the compressed air to be injected is made very fast.

  As described above, in the present embodiment, the compressed air having a high flow velocity is directly jetted toward the turbine rotor 16. Therefore, the compressed air is supplied to the exhaust system, and the pressure of the entire exhaust branch pipe 5 is increased to increase the turbine rotor. The turbine rotor 16 can be driven to rotate more responsively than the 16 can be driven to rotate.

  In the middle of the pipe 30, a positive pressure control valve 27 is provided. By opening and closing the control valve 27, it is possible to control whether or not the compressed air is ejected from the nozzle 31. Further, an auxiliary positive pressure generator 28 is connected between the positive pressure control valve 27 of the pipe 30 and the air tank 26. The auxiliary positive pressure generator 28 is operated by a hydraulic servo (not shown), generates compressed air, and increases the pressure of the compressed air from the air tank 26 by additionally supplying the compressed air to the nozzle 31 via the control valve 27. Can do.

  The air tank 26 is connected to a booster device for a foot brake (not shown) mounted on the same vehicle on which the engine 1 is mounted, and the compressed air in the air tank 26 is a boost source of the booster device for the foot brake. As a common use.

  In general, a booster for a foot brake using a compressed air as a boosting source is mounted on a commercial vehicle such as a truck having a relatively large load. The foot brake booster includes an air compressor that generates compressed air that serves as a boost source, and an air tank that stores the compressed air. In the present embodiment, since the air compressor and the air tank are used as part of the components of the positive pressure supply device 24, the air compressor 25 and the air tank 26 can be shared.

  As shown in FIG. 1, an accelerator opening sensor 10 that detects the accelerator opening is attached to the engine 1, and a pressure sensor 29 that detects the pressure P in the air tank 26 is attached. Further, the engine 1 includes various sensors (not shown) required for operating the engine 1 (for example, a crank angle sensor, a water temperature sensor, an intake pressure sensor, an intake temperature sensor, an air flow meter, an intake throttle valve opening sensor, etc.). Is attached. The accelerator opening sensor 10, the pressure sensor 29, and various sensors are connected to an electronic control unit (hereinafter referred to as ECU) 11 for engine control via an electric line.

  The ECU 11 is configured by connecting a CPU, a ROM, a RAM, and the like to each other via a bidirectional bus. The ECU 11 determines the operating state of the engine 1 using the output signals of the various sensors as parameters, and responds to the determined engine operating state. Thus, the fuel injection valve 7, the EGR valve 22, the vane adjusting actuator 20, the intake throttle valve 8, and the like are controlled. The ECU 11 includes an acceleration request determination unit that determines a driver's acceleration request, and a control unit that controls the positive pressure supply device 24. The control unit further includes a positive pressure control valve. 27 is provided with prohibiting means for prohibiting the opening of the valve 27 and auxiliary positive pressure control means for controlling the auxiliary positive pressure generator 28.

  The acceleration request determination means acquires an opening signal from the accelerator opening sensor 10, and calculates the change amount of the accelerator opening per unit time based on the signal. Then, it is determined whether or not the driver requests acceleration based on whether or not the amount of change is equal to or greater than a predetermined value. When it is determined that the driver is accelerating, a signal corresponding to the control means for controlling the positive pressure supply device 24 is transmitted.

  The control means for controlling the positive pressure supply device 24 controls the air compressor 25 and the positive pressure control valve 27, and signals from the acceleration request determination means and signals from the pressure sensor 29 provided in the air tank 26. Control based on

  When the control means acquires an acceleration request signal from the acceleration request determination means and a signal indicating that the pressure is higher than the first pressure P1 and the second pressure P2 from the pressure sensor 29, the control means outputs a signal for opening the positive pressure control valve 27. The positive pressure control valve 27 is opened by a drive circuit (not shown).

  When the positive pressure control valve 27 is opened, the compressed air in the air tank 26 is ejected from the nozzle 31 through the pipe 30 toward the turbine rotor 16, and the driving force contributing to the rotation of the turbine rotor 16 is generated. The increase rate of the rotation speed of the turbine rotor 16 increases (see FIG. 3). By increasing the rate of increase in the rotational speed of the turbine rotor 16, the supercharging pressure can be quickly raised and the acceleration performance can be improved.

  The first pressure P1 indicates the minimum pressure of the compressed air supplied to the booster for the foot brake, that is, a pressure value for ensuring the operation of the foot brake. The second pressure P <b> 2 indicates a minimum pressure value necessary for reliably rotating the turbine rotor 16 by the pressure of the compressed air in the air tank 26. Specifically, this pressure value causes the turbine rotor 16 to be rotationally driven by the pressure generated by the flow of exhaust gas at the time of initial acceleration request from the low speed operation, and to produce a rotational drive exceeding that rotational drive. Indicates the minimum pressure value required.

  Further, the pressure value of the second pressure P2 may be a value that varies according to the pressure value of the exhaust system of the engine 1 at the time of the initial acceleration request. At this time, it is conceivable to obtain the pressure value of the exhaust system by using an exhaust pressure sensor (not shown) attached to the exhaust branch pipe 5 or estimating it from the operating state of the engine 1.

  The prohibiting unit controls the positive pressure control valve 27 to forcibly close the valve. When the prohibiting means acquires a signal indicating that the pressure is equal to or lower than the first pressure P1 from the pressure sensor 29, the prohibiting means transmits a signal for forcibly closing the positive pressure control valve 27 even if an acceleration request signal is acquired. The positive pressure control valve 27 is closed by the drive circuit. Thereby, the compressed air in an air tank can be ensured for boosters, and a vehicle can be run safely.

  When the auxiliary positive pressure control means for controlling the auxiliary positive pressure generator 28 obtains a signal indicating from the pressure sensor 29 that the pressure is equal to or higher than the first pressure P1 and equal to or lower than the second pressure P2, the auxiliary positive pressure generator 28 Is transmitted, the auxiliary positive pressure generator 28 is operated by a drive circuit (not shown), and the compressed air is supplied to the turbine rotor 16. Thus, when the pressure P in the air tank is equal to or higher than the first pressure P1 and equal to or lower than the second pressure P2, the auxiliary positive pressure control means reliably rotates the turbine rotor 16 with the compressed air in the air tank 26. Since it is determined that the auxiliary positive pressure generating device 28 is operated, the turbine rotor 16 can be rotationally driven by the compressed air generated by the device 28.

  Next, the operation of the positive pressure supply device 24 executed by the ECU 11 will be described with reference to FIGS. FIG. 2 is a flowchart showing a control routine of the positive pressure supply device 24 executed by the ECU 11. FIG. 3 is a time chart showing the processing in the ECU 11 and the operating state of the turbine rotor 16 when the positive pressure supply device 24 is operated.

  In step S101, the ECU 11 determines whether an acceleration diagnosis permission flag indicating that the diagnosis of the acceleration state of the vehicle is permitted is ON (acceleration diagnosis permitted) or OFF (acceleration diagnosis not permitted). If the acceleration diagnosis is permitted, the process proceeds to step S102 to calculate the change amount of the accelerator opening per unit time based on the opening signal from the accelerator opening sensor 10, and the change amount is equal to or greater than a predetermined value. It is determined whether or not.

  This is for determining whether or not the driver is going to accelerate the vehicle. The determination of the acceleration request can be made by calculating the fuel injection amount or the change amount of the rotation speed of the crankshaft in addition to the method of determining by the accelerator opening. Preferably, it is possible to detect the driver's acceleration request more responsively and to further improve the acceleration performance by determining the acceleration request based on the amount of change in the accelerator opening that directly reflects the driver's will. .

  If the acceleration diagnosis is not permitted, the process proceeds to step S116, and it is determined whether the amount of change in the accelerator opening is equal to or greater than a predetermined value, as in step S102. If it is equal to or greater than the predetermined value, the process of step S116 is repeated until the accelerator change amount becomes less than the predetermined value. If the accelerator change amount is less than the predetermined value, the process proceeds to step S117, the acceleration diagnosis permission flag is turned ON, and this control routine is ended (see FIGS. 3A and 3B).

  If it is determined in step S102 that the amount of change in the accelerator opening is equal to or greater than the predetermined value, the ECU 11 turns off the acceleration diagnosis permission flag in step S103, and then turns on the acceleration determination flag in step S104. To do. In step S105, the ON time T is set as the predetermined time T of the acceleration determination flag (see FIGS. 3B and 3C).

  The ON time T is set to ensure that positive pressure is applied to the turbine rotor 16 in various operating states of the engine 1. In this case, the engine when the acceleration determination flag is turned ON is set. It is set based on the number of revolutions. For example, the lower the engine speed, the longer the ON time T of the acceleration determination flag. This is because when the engine speed is low, the exhaust pressure of the exhaust branch pipe 5 is relatively low, and even if the vane 18 is adjusted to the closed side, the flow rate of the exhaust gas introduced into the turbine rotor 16 does not increase. . Therefore, the required exhaust pressure is secured by increasing the ON time T.

  Next, when the process proceeds to step S106, the ECU 11 determines whether or not the ON time T of the acceleration determination flag set in step S105 has elapsed. If the acceleration determination flag ON time T has not elapsed, the process advances to step S107 to determine whether or not the acceleration determination flag is ON. If the ON time T of the acceleration determination flag has elapsed, the process proceeds to step S118, the acceleration determination flag is turned OFF, and the process proceeds to step S107 (see FIG. 3C).

  If it is determined in step S102 that the change amount of the accelerator opening is less than the predetermined value, the ECU 11 advances the process to step S118, turns off the acceleration determination flag, and advances the process to step S107.

  In step S107, the ECU 11 determines whether or not the acceleration determination flag is ON. If the acceleration determination flag is ON, the positive pressure control valve opening flag is turned ON in step S108, and the process proceeds to step S110. If the acceleration determination flag is OFF, the positive pressure control valve opening flag is turned OFF in step S109, and the process proceeds to step S110 (see FIG. 3D).

  In step S110, the ECU 11 determines whether or not the positive pressure control valve opening flag is ON. If the positive pressure control valve opening flag is ON, the process proceeds to step S111. If the positive pressure control valve opening flag is OFF, the process proceeds to step S113, the positive pressure control valve 27 is closed, and the process proceeds to step S116.

  In step S111, the ECU 11 determines whether or not the pressure P in the air tank 26 is equal to or lower than the first pressure P1. If the pressure P is not less than or equal to the first pressure P1, the process proceeds to step S112, the positive pressure control valve 27 is opened, and the process proceeds to step S114. If the pressure P is less than or equal to the first pressure P1, the process proceeds to step S113, the positive pressure control valve 27 is forcibly closed, and the process proceeds to step S116. The processing from step S111 to step S113 is for ensuring the pressure of the compressed air supplied to the booster for the foot brake. The ECU 11 forcibly closes the positive pressure control valve 27 when the pressure P in the air tank 26 is equal to or lower than the first pressure P1.

  In step S114, it is determined whether or not the pressure in the air tank 26 is equal to or lower than the second pressure P2. If the pressure P is not less than or equal to the second pressure P2, the process returns to step S106. If the pressure P is less than or equal to the second pressure P2, the process proceeds to step S115, the auxiliary positive pressure generator 28 is activated, and the process returns to step S106. The processing in step S114 is for determining whether or not the turbine rotor 16 can be reliably rotated only by the compressed air in the air tank 26. The second pressure P2 is larger than the first pressure P1 (P2> P1). If the ECU 11 is in a state where the turbine rotor 16 cannot be reliably rotated in the air tank 26, the ECU 11 supplies the turbine rotor 16 with the compressed air generated by the auxiliary positive pressure generator 28 that is hydraulically operated. The turbine rotor 16 is rotationally driven (see FIGS. 3E and 3F).

  In this control routine, the process returns from step S114 or step S115 to step S106 again. The processing is repeated until the ON time T of the acceleration determination flag elapses or until the pressure P in the air tank 26 becomes equal to or lower than the first pressure P1 and the positive pressure control valve 27 is closed. In this embodiment, ECU11 when performing the process of step S114 and step S115 functions as an auxiliary | assistant positive pressure control means.

  If the ECU 11 determines in step S110 that the positive pressure control valve opening flag is not ON, or if it is determined in step S111 that the pressure P in the air tank 26 is equal to or lower than the first pressure P1, the process proceeds to step S113. The pressure control valve 27 is closed. In this embodiment, ECU11 when performing the process of step S111 and step S113 functions as a prohibition means.

  In step S116, the ECU 11 determines whether or not the amount of change in the accelerator opening is equal to or greater than a predetermined value. If the amount of change is equal to or greater than the predetermined value, the process is repeated until the determination in step S116 is negative (times t1 to t2 in FIG. 3). If it is determined that the amount of change is less than the predetermined value, the acceleration diagnosis permission flag is turned ON in step S117 (time t3 in FIG. 3), and this control routine is terminated.

  As described above, the processing in the ECU 11 when the positive pressure supply device 24 is operated has been described. Next, how the rotational speed of the turbine rotor 16 changes by the processing in the ECU 11 will be described based on the time chart of FIG.

  As shown in FIG. 3, when the acceleration diagnosis permission flag is ON, that is, when acceleration diagnosis is permitted, the ECU 11 determines the acceleration determination flag ON time when determining that the amount of change in the accelerator opening is equal to or greater than a predetermined value. After the setting, the acceleration determination flag is turned ON (time t1).

  When the ECU 11 determines that the acceleration determination flag is ON, the ECU 11 determines whether or not the pressure P in the air tank 26 is less than or equal to the first pressure P1, and if not, the ECU 11 opens the positive pressure control valve. The valve flag is turned ON and the positive pressure control valve 27 is opened. While the positive pressure control valve opening flag is ON, the positive pressure control valve 27 is opened (time t1 to t2).

  By opening the positive pressure control valve 27, the compressed air in the air tank 26 is ejected toward the turbine rotor 16, and the driving force contributing to the rotation of the turbine rotor 16 increases. As a result, the rate of increase in the rotational speed is increased compared to when the turbine rotor 16 is rotated only by the exhaust gas pressure of the conventional exhaust gas (shown by the broken line in FIG. 3). When the rate of increase in the rotational speed increases, the target turbine rotor rotational speed is reached in a shorter time than in the prior art, and the supercharging pressure can be quickly raised, so that the acceleration performance can be improved.

  In the present embodiment, the turbine rotor 16 is rotated without directly attaching an auxiliary device that increases the rotational moment to the turbine rotor 16, the compressor rotor 14, and the turbo rotating shaft 17 that are the rotating elements of the variable nozzle turbocharger 12. Since it is set as the structure which assists a drive, the response of the turbine rotor 16 becomes better than this.

1 is an overall configuration diagram of an engine according to an embodiment of the present invention. It is a flowchart which shows the control routine of the positive pressure supply apparatus which ECU performs. It is a time chart which shows the process in ECU when operating a positive pressure supply apparatus, and the operating state of a turbine rotor.

Explanation of symbols

1 Engine 10 Accelerator opening sensor 11 Electronic control unit 12 Variable nozzle turbocharger 16 Turbine rotor 24 Positive pressure supply device (auxiliary means)
25 Air Compressor 26 Air Tank 27 Positive Pressure Control Valve 28 Auxiliary Positive Pressure Generator 29 Pressure Sensor 31 Nozzle

Claims (9)

A turbine rotor provided in an exhaust path of the internal combustion engine, a variable vane that opens and closes to make the flow rate of exhaust gas that drives the turbine rotor variable, and an internal combustion engine that is provided in an intake path according to the driving torque of the turbine rotor. In a supercharging control device for an internal combustion engine for controlling a variable nozzle turbocharger having a compressor for supplying air to the engine,
Acceleration request determination means for determining whether or not the driver has requested acceleration;
Auxiliary means for assisting the rotational drive of the turbine rotor;
A supercharging control device for an internal combustion engine, comprising: a control unit that activates the auxiliary unit when the acceleration request determination unit determines that the driver has requested acceleration.   The supercharging control device for an internal combustion engine according to claim 1, wherein the auxiliary means is a positive pressure supply means for supplying a positive pressure exceeding a pressure generated by a flow of exhaust gas to the exhaust passage. The positive pressure supply means includes
An air compressor that generates positive pressure;
An air tank for accumulating positive pressure generated by the air compressor;
A nozzle portion connected to the air tank and having a jet outlet directed to the turbine rotor;
The supercharging control device for an internal combustion engine according to claim 2, comprising a control valve that controls supply of positive pressure ejected from the nozzle portion.   The internal combustion engine according to claim 3, wherein the air compressor and the air tank are an air compressor and an air tank used for a booster device for a foot brake mounted on a vehicle on which the internal combustion engine is mounted. Supercharging control device. A pressure sensor for measuring the pressure in the air tank;
5. The internal combustion engine according to claim 3, wherein the control unit includes a prohibiting unit that prohibits the control valve from opening when the pressure sensor detects a pressure equal to or lower than a first pressure. 6. Supercharging control device. Auxiliary positive pressure generating means that is operated by hydraulic pressure, generates positive pressure, and supplies positive pressure to the auxiliary means,
The control means includes auxiliary positive pressure control means for operating the auxiliary positive pressure generating means when the pressure sensor detects a pressure not lower than the first pressure and not higher than a second pressure. The supercharging control device for an internal combustion engine according to claim 5.   The supercharging control device for an internal combustion engine according to claim 5 or 6, wherein the first pressure is a pressure value that ensures the operation of the foot brake by the booster.   The said 2nd pressure is a pressure value required in order to produce the rotational drive exceeding the rotational drive by which the said turbine rotor is rotationally driven by the pressure which arises by the distribution | circulation of waste gas, It is characterized by the above-mentioned. The supercharging control apparatus for internal combustion engines as described.   9. The internal combustion engine overload according to claim 2, wherein the auxiliary means supplies the positive pressure for a predetermined time determined according to an operating state of the internal combustion engine. Feed control device.

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