JP4295753B2 - Supercharging pressure control device for internal combustion engine - Google Patents

Description

  The present invention relates to a supercharging pressure control method using a turbocharger of an internal combustion engine. More specifically, the present invention relates to a supercharging pressure control method using a turbocharger provided with an electric motor for adjusting the supercharging pressure.

  A turbocharger is a device for increasing the capacity of an internal combustion engine by compressing intake air using exhaust gas from the internal combustion engine. The basic configuration of a turbocharger is provided with a compressor (intake side) and a turbine (exhaust side) at both ends of a rotating shaft. Exhaust air is caused to flow through the turbine and rotated, whereby the intake air is compressed by the rotating compressor. The turbocharger has high efficiency because it uses the energy of exhaust gas that is originally discarded, and has been widely used so far. However, there is a problem that when the engine is low speed, the effect is difficult to be obtained because there is little exhaust, and even if the rotational speed at which the effect of air compression is achieved, a slight delay occurs until the effect is actually achieved.

  In order to compensate for such an insufficient output of the supercharging pressure, for example, Patent Document 1 discloses a turbocharger with an electric motor that realizes a desired supercharging pressure by forcibly driving the turbine by incorporating the electric motor into the turbine. Yes. The target supercharging pressure is searched based on the operating state, and the power supplied to the electric motor is controlled according to the deviation from the actual supercharging pressure.

Patent Document 2 discloses a supercharging pressure control device that uses another supercharging pressure control means for a turbocharger with an electric motor. In this apparatus, in order to reduce power consumption, the boost pressure control by the control means other than the motor is prioritized over the boost pressure control by the motor. Further, the supercharging pressure can be controlled without interfering with the control of the electric motor and other means, and the output characteristics and fuel consumption are improved.
JP-A-8-182382 JP2003-239755

  However, in the invention of Patent Document 1, only the electric motor is considered as the supercharging pressure control means, and when there are a plurality of control means, the supercharging pressure control by each control means may interfere. .

  On the other hand, the invention of Patent Document 2 is not necessarily controlled in a direction not using an electric motor. In the disclosed control method, the electric motor is always used while the actual supercharging pressure is smaller than the target supercharging pressure. For this reason, power consumption may increase. Even if the predetermined value for stopping the use of the electric motor is set, trial and error adjustment is required in advance. Further, a large number of setting maps such as a supercharging pressure increase map (target value map) for the electric motor are necessary, and the setting man-hour is large.

  Therefore, the present invention provides a supercharging pressure control method that can easily adjust the distribution characteristics of input request values to a plurality of supercharging pressure control means with few parameters while preventing interference between the supercharging pressure control means. The purpose is to provide.

  The supercharging pressure control device for an internal combustion engine provided by the present invention controls the supercharging pressure by a method other than the first supercharging pressure control means for controlling the supercharging pressure using an electric motor and the first supercharging pressure control means. A second supercharging pressure control means, a supercharging pressure detecting means for detecting the actual supercharging pressure, a target supercharging pressure determining means for obtaining the target supercharging pressure, and the actual supercharging pressure to be brought close to the target supercharging pressure In addition, a first control request value calculation unit that calculates a first control request value that is a control input to the first supercharging pressure control unit, a first target value determination unit that calculates a target value of the first control request value, Second control request value calculation means for calculating a second control request value that is a control input to the second supercharging pressure control means so that the first control request value approaches the first target value.

  According to one embodiment of the present invention, the first target value is set to 0 during normal operation. The second control request value is calculated so that the first control request value converges to zero.

  According to this invention, at the beginning of the supercharging pressure control, the first supercharging pressure control means is preferentially executed, and as the first control request value converges to the first target value, the second supercharging pressure control means Since the control is executed mainly, it is possible to easily adjust the operation distribution of each controller while preventing interference between the plurality of supercharging pressure means control means. In addition, since the use of the first supercharging pressure control means that uses a motor with high energy consumption is gradually reduced, the energy consumption of the apparatus can be suppressed.

  According to an embodiment of the present invention, the first target value is set to a predetermined value during acceleration. The second boost pressure control means controls the boost pressure so that the first control request value converges to a predetermined value.

  According to one embodiment of the present invention, the supercharging pressure control device further includes a battery for driving the electric motor. When the state of charge of the battery is less than or equal to a predetermined value, the control by the first boost pressure control means is stopped.

  According to one embodiment of the present invention, the first supercharging pressure control means includes a supercharger with an electric motor and a throttle valve. When the actual supercharging pressure is lower than the target supercharging pressure, the first supercharging pressure control means outputs a control input to the supercharger with an electric motor as the difference between the actual supercharging pressure and the target supercharging pressure increases. Increase the actual supercharging pressure. Further, the first supercharging pressure control means reduces the actual supercharging pressure by setting the throttle valve opening to the close side as the difference increases when the actual supercharging pressure is higher than the target supercharging pressure. .

  According to one embodiment of the present invention, the first supercharging pressure control means includes a supercharger with an electric motor and a throttle valve. When the actual supercharging pressure is lower than the target supercharging pressure, the first supercharging pressure control means outputs a control input to the supercharger with an electric motor as the difference between the actual supercharging pressure and the target supercharging pressure increases. At the same time, increase the actual supercharging pressure by setting the opening of the throttle valve near the fully open position. Further, the first supercharging pressure control means sets the throttle valve opening to the closed side as the difference is larger when the actual supercharging pressure is higher than the target supercharging pressure, and to the supercharger with electric motor. Is set in the vicinity of a predetermined minimum value to reduce the actual supercharging pressure.

  Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a configuration diagram of an internal combustion engine (hereinafter referred to as “engine”), a turbocharger, and a control device according to a first embodiment of the present invention.

  The engine 1 is a diesel engine having four cylinders, for example. An intake pipe 2 and an exhaust pipe 3 are connected to the engine 1.

  The turbocharger 4 includes a compressor 5 provided in the intake pipe, a turbine 6 provided in the exhaust pipe, and a rotating shaft 7 that connects the compressor 5 and the turbine 6. The turbine 6 is rotationally driven by the energy of the exhaust gas. The compressor 5 is rotated by the rotation of the turbine 6, and the compressor 5 compresses the intake air.

  In the present embodiment, the turbocharger 4 is an electrically assisted turbo that further includes an electric motor 8 for applying a driving force to the rotating shaft. The turbocharger 4 is a variable geometry turbo (hereinafter referred to as “VGT”) that allows the rotational speed of the turbine 6 to be adjusted by a nozzle having a variable opening. VGT accelerates the turbine by reducing the angle of the movable vane 12 outside the turbine wheel when the flow rate of the exhaust gas is small, thereby narrowing the passage (nozzle) for blowing the gas into the turbine and blowing the gas more strongly on the turbine wheel. Improve performance.

  A boost pressure sensor 9 is provided downstream of the compressor 5. The supercharging pressure sensor 9 detects the pressure of the intake air compressed by the compressor 5, that is, the supercharging pressure.

  A flow path that bypasses the turbine 6 is provided in the exhaust pipe 3, and a waste gate valve 10 is installed on the flow path. The waste gate valve is opened when the supercharging pressure exceeds a predetermined value, and controls the supercharging pressure by reducing the exhaust flow rate to the turbine. Note that the VGT and the waste gate valve 10 have the same function of adjusting the exhaust flow rate to the turbine 6 and may include only one of them.

  An electronic control unit (hereinafter referred to as “ECU”) 11 includes an input interface 11a that receives data sent from each part of the vehicle, a CPU 11b that executes calculations for controlling each part of the vehicle, a read-only memory (ROM), and a temporary The computer includes a memory 11c having a random access memory (RAM) for storage, and an output interface 11d that sends a control signal to each part of the vehicle. The ROM of the memory 11c stores a program for controlling each part of the vehicle and various data. A program for performing supercharging pressure control according to the present invention, and data and tables used in executing the program are stored in this ROM. The read-only memory may be a rewritable ROM such as an EEPROM. The RAM is provided with a work area for calculation by the CPU 11b, and temporarily stores data sent from each part of the vehicle and control signals sent to each part of the vehicle.

  In the present embodiment, the turbine 6 is rotated by the exhaust gas of the engine 1, and the compressor 5 in the intake pipe is also rotated by the connected rotary shaft 7. The intake air is compressed by the rotation of the compressor and introduced into the engine. The actual supercharging pressure of the compressed intake air is measured by the supercharging pressure sensor 9 and sent to the input interface 11a of the ECU 11. In the ECU 11, the actual boost pressure is compared with the target boost pressure. As a result, if it is determined that the desired boost pressure cannot be realized only by the rotation by the exhaust gas, the ECU 11 is necessary for the target boost pressure. A control input is given from the output interface 11d to the electric motor 8 so that the compressor 5 can be rotated properly. In parallel with this, the ECU 11 receives a control input for determining the angle of the movable vane 12 in the turbine from the output interface 11a so that the turbine 6 can obtain the rotation required for the target supercharging pressure even at the current exhaust gas flow rate. Send to.

  FIG. 2 is a configuration diagram of an engine, a turbocharger, and a control device according to the second embodiment of the present invention. The engine 1, ECU 11, supercharging pressure sensor 9, and waste gate valve 10 are the same as those in the embodiment shown in FIG.

  The turbocharger 4 includes a compressor 5 provided in the intake pipe 2, a turbine 6 provided in the exhaust pipe 3, and a rotating shaft 7 that connects the compressor 5 and the turbine 6. The turbine 6 is rotationally driven by the energy of the exhaust gas. The compressor 5 is rotated by the rotation of the turbine 6, and the compressor 5 compresses the intake air.

  In the present embodiment, an electric compressor 13 different from the compressor 5 is installed in the intake pipe 2. An electric motor 8 is connected to the electric compressor 13. The electric motor 8 gives a driving force to the rotating shaft of the electric compressor 13 in accordance with a command value from the ECU. The supercharging pressure is adjusted by driving the electric compressor 13. In FIG. 2, the electric compressor 13 is installed on the upstream side of the compressor 5, but may be installed on the downstream side of the compressor 5 as long as it is in the intake pipe 2.

  In the present embodiment, the turbine 6 is rotated by the exhaust gas of the engine 1, and the compressor 5 in the intake pipe is also rotated by the connected rotary shaft 7. The intake air is compressed by the rotation of the compressor 5 and introduced into the engine 1. The actual supercharging pressure of the compressed intake air is measured by the supercharging pressure sensor 9 and sent to the input interface 11a of the ECU 11. In the ECU 11, the actual boost pressure and the target boost pressure are compared. As a result, when it is determined that the desired boost pressure cannot be realized only by the rotation by the exhaust gas, the ECU 11 gives a control input for driving the electric compressor 13 necessary to realize the target boost pressure. The output interface 11d supplies the electric motor 8. In parallel with this, the ECU 11 receives a control input for determining the angle of the movable vane 12 in the turbine from the output interface 11a so that the turbine 6 can obtain the rotation required for the target supercharging pressure even at the current exhaust gas flow rate. Send to.

Thus, in the first and second embodiments of the present invention, as a method for controlling the supercharging pressure, a method using the electric motor 8 illustrating the electric assist turbo or the electric compressor 13 and a method other than the electric motor illustrating the VGT are used. Applied in combination with methods. However, the supercharging pressure control method other than the electric motor is not limited to VGT. For example, the opening degree of the waste valve 10 installed on the exhaust pipe 3 on the path bypassing the turbine is electrically controlled by the ECU. A method for controlling the supercharging pressure by adjusting the flow rate of the exhaust gas to the turbine is also applicable. Moreover, in this embodiment, since VGT is used as a supercharging pressure control method, the engine 1 is a diesel engine having good compatibility with VGT. However, if another supercharging pressure control method is used, the engine 1 may be a gasoline engine.
In the embodiment of the present invention, the electric motor 8 and the VGT are applied as the supercharging pressure control means. Although the supercharging pressure control using the electric motor 8 has good responsiveness, there is a problem that energy consumption increases. On the other hand, the supercharging pressure control by VGT has poor responsiveness, but it can use the energy of the exhaust gas, so that the energy consumption is small. In order to keep energy consumption low while maintaining good response characteristics of supercharging pressure control, the motor 8 having good response is used immediately after the target supercharging pressure fluctuates, and thereafter the use of the motor 8 is reduced as much as possible. Therefore, it is desirable to shift the control initiative to VGT with low energy consumption.

  FIG. 3 is a block diagram of the supercharging pressure control device used in the first and second embodiments of the present invention. This control device simultaneously operates the electric motor 8 and the VGT to realize a target supercharging pressure of the engine 1 that is a control target. Further, the VGT controller 22 causes the control input to the motor 8 to converge to the motor input target value (0 during normal operation). Thereby, at the beginning of the supercharging pressure control, the electric motor 8 is preferentially executed, and as the control proceeds, the VGT leads the control.

First, the target boost pressure Pb_obj is determined from the operating state of the engine 1, and the actual boost pressure Pb_act is measured by the boost pressure sensor 9. Based on the error between the target boost pressure Pb_obj and the actual boost pressure Pb_act, the motor controller 21 calculates the motor input request value Ueb_dmd. In this embodiment, the motor controller 21 uses a PI controller and calculates a motor input request value Ueb_dmd as shown in the following equation.

Here, K _p1 is a proportional gain, and K _I1 is an integral gain. From the above equation, the motor input request value Ueb_dmd is set to increase as the target boost pressure Pb_obj is larger than the actual boost pressure Pb_act, especially when the target boost pressure increases stepwise. Ueb_dmd is a large value.

  The electric motor input request value is used as an input to the VGT controller 22 together with the control input of the electric motor 8.

  The electric motor input target value Ueb_obj is set according to the operating state of the engine 1. In the present embodiment, this electric motor input target value is 0 for normal travel, and is a positive value corresponding to the accelerator opening during acceleration.

Based on the error between the electric motor input target value Ueb_obj and the electric motor input request value Ueb_dmd, the VGT controller 22 calculates the VGT input request value Utb_dmd. In this embodiment, the VGT controller 22 uses a PI controller and calculates a VGT input request value Utb_dmd as shown in the following equation.

Here, _Kp2 is a proportional gain, and _KI2 is an integral gain. From the above equation, the VGT input request value Utb_dmd is set to increase as the motor input request value Ueb_dmd is larger than the motor input target value Ueb_obj.

  The VGT input request value Utb_dmd is a control input for the movable vane 12 in the turbine 6 of the turbocharger 4. The increase / decrease in the VGT input request value corresponds to the angle of the movable vane 12, that is, the nozzle opening. When the VGT input request value increases, the movable vane 12 rotates in the direction to close the nozzle. This also increases the rotational speed of the turbine. Accordingly, the rate at which the electric motor drives the rotating shaft 7 also decreases.

  FIG. 4 shows the behavior of the motor input request value Ueb_dmd, the VGT input request value Utb_dmd, and the actual boost pressure Pb_act when the step-like target boost pressure Pb_obj is input to the first and second embodiments of the present invention. It is a graph to show. In the present embodiment, the control input to the electric motor and the VGT is a duty ratio, and the vertical axes in FIGS. 4A and 4B are also represented by the duty ratio.

  When the target boost pressure 31 increases stepwise at the time Ta, the motor input request value 33 increases in order to eliminate the error from the actual boost pressure 32. Furthermore, the VGT input request value 34 also increases in order to eliminate the error between the motor input request value 33 and the motor input target value Ueb_obj.

  The electric motor 8 and VGT are driven simultaneously by the electric motor input request value 33 and the VGT input request value 34 immediately after the time Ta. Thereby, sufficient rotational force is given to the compressor 5, and the actual supercharging pressure 32 quickly follows the target supercharging pressure 31.

  Thereafter, as the supercharging pressure stabilizes in a steady state, the motor input request value 33 that is a control input to the motor 8 gradually decreases and converges to the motor input target value Ueb_obj, and the VGT leads the supercharging pressure. Come to control. The motor input target value Ueb_obj is 0 during normal running, and the motor 8 stops when the motor input request value 33 converges to the motor input target value Ueb_obj. Here, in the case of a type that is not interlocked with the turbine 6 such as the electric compressor 13 shown in FIG. 2, when the electric motor 8 stops, the rotation of the compressor also stops and intake air is not introduced into the intake pipe 2. Intake air is introduced by, for example, a method of providing a bypass passage (not shown) that bypasses 13.

  On the other hand, the VGT input request value 34 converges to a value that can maintain the target boost pressure. This VGT input request value corresponds to the angle of the movable vane 12 in the turbine.

  5 and 6 are flowcharts of cooperative control of the electric motor 8 and the VGT by the supercharging pressure control device of the first and second embodiments of the present invention. Note that k used in the following description represents the current value. Further, k−1 is the previous value one step before.

  In step S101, the target boost pressure Pb_obj (k) is determined according to the driving state of the vehicle. The target boost pressure is determined, for example, by searching a map created based on engine speed and engine torque (load).

  In step S102, the actual boost pressure Pb_act (k) in the intake pipe is detected from the boost pressure sensor 9.

  In step S103, the control error Eeb (k) of the motor controller 21 is calculated by subtracting the actual boost pressure from the target boost pressure. The calculation is as follows.

Eeb (k) = Pb_obj (k) − Pb_act (k)
In step S104, an integral value SEeb (k) of the control error Eeb (k) is calculated. The calculation is as follows. Here, h represents a sampling time.

SEeb (k) = SEeb (k-1) + h * Eeb (k)
In step S105, the motor controller 21 determines the motor input request value Ueb_dmd (k). In the present embodiment, since the motor controller 21 is a PI controller, the motor input request value Ueb_dmd (k) is calculated as in the following equation.

Ueb_dmd (k) = Kp1 * Eeb (k) + Ki1 * SEeb (k)
Here, Kp1 is a proportional gain of the motor controller 21, and Ki1 represents an integral gain of the motor controller 21. The electric motor input request value Ueb_dmd (k) is used as an input to the VGT controller 22 as well as being input to the electric motor 8 in the turbocharger 4.

  In step S106, the motor input target value Ueb_obj (k) is determined. The motor input target value is determined by the driving state of the vehicle using the subroutine shown in FIG.

  In the subroutine for determining the electric motor input target value, first, in step S107, the required torque Tq_dmd is obtained according to the operating state of the engine (for example, the engine speed). Then, this required torque Tq_dmd is compared with a predetermined acceleration judgment torque Tq_acc. If the required torque Tq_dmd is smaller than the acceleration determination torque Tq_acc, it is determined that the vehicle is in normal operation, and the process proceeds to step S108. On the other hand, when the required torque Tq_dmd is larger than the acceleration determination torque Tq_acc, it is determined that the vehicle is in an acceleration operation, and the process proceeds to step S109.

  In step S108, the electric motor input target value Ueb_obj (k) is set to zero. Then, the process returns to the main routine and proceeds to step S111.

  In step S109, it is checked whether the SOC (state of charge) is equal to or greater than a predetermined value. If the SOC is equal to or greater than the predetermined value, the process proceeds to step S110, and the motor input target value Ueb_obj (k) is set to a positive value Ueb_acc corresponding to the accelerator opening, and the process returns to the main routine. When the SOC is less than or equal to a predetermined value, the motor input target value Ueb_obj (k) is set to 0 in order to reduce the drive of the motor 8 with large energy consumption in order to suppress the power consumption of the battery.

  Returning to the main routine of FIG. 5, in step S111, the motor input target value Ueb_obj (k) determined in the subroutine is subtracted from the motor input request value Ueb_dmd (k) to calculate the control error Etb (k) of the VGT controller 22. To do. The calculation is as follows.

Etb (k) = Ueb_dmd (k) −Ueb_obj (k)
In step S112, an integral value SEtb (k) of the control error Etb (k) is calculated. The calculation is as follows. Here, h represents a sampling time.

SEtb (k) = SEtb (k-1) + h * Etb (k)
In step S113, the VGT controller 22 determines the VGT input request value Utb_dmd (k). In the present embodiment, since the VGT controller 22 is a PI controller, the VGT input request value Utb_dmd (k) is calculated as in the following equation.

Utb_dmd (k) = Kp2 * Etb (k) + Ki2 * SEtb (k)
Here, Kp2 is a proportional gain of the VGT controller 22, and Ki2 represents an integral gain of the VGT controller 22. This VGT input request value Utb_dmd (k) is input to the movable vane 12 in the turbine 6 of the turbocharger 4.

  Subsequently, third and fourth embodiments of the present invention will be described.

  FIG. 7 is a configuration diagram of an engine, a turbocharger, and a control device according to the third embodiment of the present invention. In this embodiment, a throttle valve 15 is added to the configuration of the first embodiment. Since the engine 1, the ECU 11, the turbocharger 4, the supercharging pressure sensor 9, and the waste gate valve 10 are the same as those in the first embodiment, description thereof is omitted.

  The throttle valve 15 is installed at an arbitrary position in the intake pipe 2 downstream of the compressor 5 and upstream of the supercharging pressure sensor 9. In the present embodiment, the throttle valve 15 is an electric throttle that is driven by an actuator (not shown) in accordance with a control signal from the ECU 11. The throttle valve 15 is kept at the maximum opening degree during normal operation of the engine 1, and is controlled to the closed side to take in the intake air for specific applications such as regeneration processing of an exhaust diesel particulate filter (not shown). Work to squeeze.

  FIG. 8 is a configuration diagram of an engine, a turbocharger, and a control device according to a fourth embodiment of the present invention. In this embodiment, a throttle valve 15 is further added to the second embodiment. The engine 1, ECU 11, turbocharger 4, supercharging pressure sensor 9, waste gate valve 10, and electric compressor 13 are the same as those in the second embodiment, and the throttle valve 15 is the same as that in the third embodiment. Description is omitted.

  In the third and fourth embodiments of the present invention, the turbine 6 is rotated by the exhaust gas of the engine 1, and the compressor 5 in the intake pipe 2 is also rotated by the connected rotary shaft 7. The intake air is compressed by the rotation of the compressor 5 and introduced into the engine.

  The actual supercharging pressure of the compressed intake air is measured by the supercharging pressure sensor 9 and sent to the input interface 11a of the ECU 11. In the ECU 11, the actual boost pressure and the target boost pressure are compared. As a result, when it is determined that the desired boost pressure cannot be realized only by the rotation of the compressor 5 by the exhaust gas, the ECU 11 can connect the motor 8 or the throttle valve from the output interface 11d so that the target boost pressure can be realized. 15 gives a control input.

  In parallel with the control of the electric motor 8 or the throttle valve 15, the ECU 11 determines the angle of the movable vane 12 in the turbine so that the turbine 6 can obtain the rotation required for the target boost pressure even at the current exhaust flow rate. To the turbine 6 from the output interface 11a.

  As described above, in the third and fourth embodiments of the present invention, as a method for controlling the supercharging pressure, two or more actuator groups (the electric motor 8 and the throttle valve 15) that have quick response but large energy consumption. Low-frequency control method using one or more actuator groups (VGT; hereinafter referred to as “low-frequency side actuator”), and high-frequency control method based on “high-frequency side actuator”) and low response but low energy consumption The method is applied in combination.

  Here, the actuator that is the target of the low-frequency control method is not limited to the VGT. For example, the opening degree of the waste valve 10 installed on the path that bypasses the turbine in the exhaust pipe 3 is electrically controlled by the ECU. It is also possible to apply a method of controlling the supercharging pressure by adjusting the flow rate of the exhaust gas to the turbine. Moreover, in this embodiment, since VGT is used as a supercharging pressure control method, the engine 1 is a diesel engine having good compatibility with VGT. However, if another supercharging pressure control method is used, the engine 1 may be a gasoline engine.

  FIG. 9 is a block diagram of a supercharging pressure control device used in the third and fourth embodiments of the present invention. This control device realizes a target boost pressure Pb_obj of the engine to be controlled by simultaneously operating the high-frequency side actuator and the low-frequency side actuator in the supercharging pressure control.

This control device converts a control input U _H _cmd to a high frequency side actuator into a high frequency control input target value U _H _obj (during normal operation) by a low frequency side actuator controller (hereinafter referred to as “low frequency side controller”) 32. 0). Thereby, initially, the high-frequency side actuator (the electric motor 8 and the throttle valve 15) is preferentially driven, and as the control input U _H _cmd to the high-frequency side actuator converges to the target value U _H _obj, the low-frequency side actuator (VGT) is driven in a leading manner.

Hereinafter, the supercharging pressure control according to the present embodiment will be described with reference to FIG. First, the target boost pressure Pb_obj is determined from the operating state of the engine 1, and the actual boost pressure Pb_act is measured by the boost pressure sensor 9. Based on the error between the target boost pressure Pb_obj and the actual boost pressure Pb_act, the high-frequency actuator controller (hereinafter referred to as “high-frequency controller”) 31 calculates the high-frequency control input U _H _cmd. In this embodiment, the high frequency side controller 31 uses a PI controller and calculates a high frequency side control input U _H _cmd as shown in the following equation.

Here, K _pH is a proportional gain, and K _IH is an integral gain. From the above equation, as the target boost pressure Pb_obj is larger than the actual boost pressure Pb_act, the high-frequency side control input U _H _cmd increases in the positive direction, and as the target boost pressure Pb_obj is smaller than the actual boost pressure Pb_act, the higher frequency side The control input U _H _cmd is set to increase in the negative direction. In particular, when the target supercharging pressure increases or decreases stepwise, the high-frequency side control input U _H _cmd varies greatly.

The high band side control input U _H _cmd calculated by the high band side controller 31 is distributed to the high band side actuator group (the electric motor 8 and the throttle valve 15) via the high band control input distributor 33. The high frequency control input distributor 33 determines a control input to each actuator according to the high frequency control input U _{H —} cmd so that interference between the actuators does not occur.

  The high frequency control input distributor 33 is provided with a control input distribution table as shown in FIG. 10, for example, and the control input to the electric motor 8 and the throttle valve 15 is determined by this table. In the present embodiment, the control inputs Ueb and Uth to the electric motor 8 and the throttle valve 15 are duty ratios.

FIG. 10A shows a table for determining the control input Ueb of the electric motor 8 that drives the supercharger with electric motor. The high-frequency side control input U _H _cmd is the horizontal axis, and the control input Ueb to the electric motor 8 is vertical. It is the graph which took and represented on the axis | shaft. In the present embodiment, the control input Ueb to the electric motor 8 is the duty ratio, and the vertical axis in FIG. 10A is also represented by the duty ratio.

Referring to FIG. 10 (a), the control input Ueb of the electric motor 8 increases monotonously according to the magnitude of the high frequency control input U _H _cmd when the high frequency control input U _H _cmd is a positive value. Go. Such a monotonous increase in the control input Ueb continues until the rotational speed of the electric motor 8 reaches a maximum value Ueb_max that becomes a predetermined maximum rotational speed (for example, 200,000 rpm), and thereafter becomes constant at the maximum value Ueb_max. When the high frequency side control input U _H _cmd is 0 or less, the control input Ueb of the electric motor 8 is constant at the minimum value Ueb_min. The minimum value Ueb_min of the control input to the electric motor 8 is 0 in this embodiment, and the electric motor 8 stops when the control input is 0. Here, in the case of a type that does not interlock with the turbine 6 such as the electric compressor 13 shown in FIG. 8, when the electric motor 8 stops, the rotation of the compressor also stops and intake air is not introduced into the intake pipe 2. Intake air is introduced by, for example, a method of providing a bypass passage (not shown) that bypasses 13.

On the other hand, FIG. 10B is a diagram showing a table for determining the control input Uth of the throttle valve 15 in a graph format. The horizontal axis of the graph represents the high frequency side control input U _H _cmd, and the vertical axis represents the opening θth of the throttle valve 15.

Figure 10 (b), the opening degree θth of the throttle valve 15, when the high frequency side control input U _H _cmd is negative, monotonically decreasing in accordance with the magnitude of the high frequency side control input U _H _cmd To go. Such a monotonous decrease in the throttle opening θth continues until the minimum opening θth_min at which the engine 1 can maintain the idle rotation speed, and thereafter becomes constant at the minimum value θth_min. When the high frequency side control input U _{H —} cmd is 0 or more, the opening θth of the throttle valve 15 is constant at the maximum value θth_max.

  The control input Uth of the throttle valve 15 is calculated according to the opening degree θth of the throttle valve. The throttle valve 15 according to the present embodiment has a maximum opening degree θth_max when the control input is zero. Accordingly, when the opening degree θth of the throttle valve 15 is fully open (θth_max), the control input Uth is calculated as 0, and the control input Uth increases as the opening degree θth of the throttle valve 15 shifts to the closing side.

Thus, in this embodiment, the electric motor 8 of the supercharger with electric motor and the throttle valve 15 are selectively used according to the positive / negative of the high-frequency side control input U _H _cmd. When the high-frequency side control input U _H _cmd is positive, the supercharger with electric motor mainly controls the supercharging pressure by adjusting the rotation of the compressor. On the other hand, when the high frequency side control input U _H _cmd is negative, the throttle valve 15 mainly controls the supercharging pressure by adjusting the throttle opening to throttle the intake air. Such a setting makes it possible to avoid the occurrence of interference between the supercharger with electric motor and the throttle valve.

Returning to FIG. 9 again and continuing the description, the high-frequency side control input U _{H —} cmd is used as an input to the low-frequency side controller 32 in addition to being a control input for the high-frequency side actuator.

The high-frequency control input target value U _{H —} obj is set according to the operating state of the engine 1. In the present embodiment, the high-frequency control input target value U _{H —} obj is 0 during normal traveling, and is a positive value corresponding to the accelerator opening during acceleration.

Based on the error between the high frequency control input target value U _{H —} obj and the high frequency control input U _{H —} cmd, the low frequency controller 32 calculates the low frequency control input U _{L —} cmd. In this embodiment, the low frequency side controller 32 uses a PI controller and calculates a low frequency side control input U _L _cmd as shown in the following equation.

Here, K _pL is a proportional gain, and K _IL is an integral gain. From the above equation, the higher frequency side control input U _H _cmd is greater than the high-frequency control input target value U _H _obj lower frequency control input U _L _cmd increases in the positive direction, the high high frequency side control input U _H _cmd The lower band control input U _L _cmd is set to increase in the negative direction as it is smaller than the band control input target value U _H _obj.

The low frequency side control input U _L _cmd, in this embodiment, the control input of the variable vane 12 of the turbine 6 of the turbocharger 4. Increase or decrease in the low frequency side control input U _L _cmd, the angle of the movable vane 12, i.e. corresponding to the nozzle opening. When the low-frequency side control input U _{L —} cmd increases in the positive direction, the movable vane 12 rotates in the direction to close the nozzle, and the turbine speed increases. Further, the low frequency side control input U _L _cmd increases in the negative direction, the movable vane 12 is rotated in the direction of closing the nozzle, the rotation speed of the turbine is reduced.

  11 and 12 are flowcharts of cooperative control of the electric motor 8, the throttle valve 15, and the VGT by the supercharging pressure control device of the third and fourth embodiments of the present invention. Note that k used in the following description represents the current value. Further, k−1 is the previous value one step before.

  In step S201, the target boost pressure Pb_obj (k) is determined according to the driving state of the vehicle. The target boost pressure is determined, for example, by searching a map created based on engine speed and engine torque (load).

  In step S202, the actual boost pressure Pb_act (k) in the intake pipe 2 is detected from the boost pressure sensor 9.

In step S203, a control error E _H (k) of the high frequency side controller 31 is calculated by subtracting the actual boost pressure from the target boost pressure. The calculation is as follows.

E _H (k) = Pb_obj (k) − Pb_act (k)
In step S104, it computes the integral value SE _H of the control error E _H (k) a (k). The calculation is as follows. Here, h represents a sampling time.

SE _H (k) = SE _H (k-1) + h * E _H (k)
In step S205, the high frequency side controller 31 determines the high frequency side control input U _{H —} cmd (k). In the present embodiment, since the high band side controller 31 is a PI controller, the high band side control input U _{H —} cmd (k) is calculated as follows.

U _H _cmd (k) = K _pH * Eeb (k) + K _iH * SEeb (k)
Here, K _pH is a proportional gain of the high frequency controller 31, and _KiH represents an integral gain of the high frequency controller 31. The high frequency side control input U _{H —} cmd (k) is used as a control input to the electric motor 8 and the throttle valve 15 in the turbocharger 4 and also used as an input to the low frequency side controller 32.

In step S206, a high frequency control input target value U _{H —} obj (k) is determined. The high frequency control input target value U _{H —} obj is determined by the driving state of the vehicle using the subroutine shown in FIG.

  In the subroutine for determining the motor input target value, first, in step S207, the required torque Tq_dmd is obtained according to the engine operating state (for example, the engine speed). Then, this required torque Tq_dmd is compared with a predetermined acceleration judgment torque Tq_acc. If the required torque Tq_dmd is smaller than the acceleration determination torque Tq_acc, it is determined that the vehicle is in normal operation, and the process proceeds to step S208. On the other hand, when the required torque Tq_dmd is larger than the acceleration determination torque Tq_acc, it is determined that the vehicle is in an acceleration operation, and the process proceeds to step S209.

In step S208, the high frequency control input target value U _{H —} obj (k) is set to zero. Then, the process returns to the main routine and proceeds to step S211.

In step S209, it is checked whether the SOC (state of charge) is equal to or greater than a predetermined value. When the SOC is equal to or greater than the predetermined value, the process proceeds to step S210, where the high-frequency control input target value U _{H —} obj (k) is set to a positive value U _{H —} acc according to the accelerator opening, and the process returns to the main routine. When the SOC is equal to or lower than a predetermined value, the high-frequency control input target value U _{H —} obj (k) is set to 0 in order to reduce the drive of the motor that consumes a large amount of energy in order to suppress the power consumption of the battery.

Returning to the main routine of FIG. 11, in step S211, the high frequency control input distributor 33 controls the control input Ueb (k) of the motor 8 and the throttle valve 15 according to the high frequency control input U _{H —} cmd (k). Determine the input Uth (k). The high frequency control input distributor 33 includes a control input distribution table corresponding to each of the electric motor 8 and the throttle valve 15 as shown in FIG. 10, for example, and the high frequency side control input U _H is used using these tables. Determine each control input according to _cmd (k).

In step S212, the control error E _L (k) of the low frequency controller 32 is obtained by subtracting the high frequency control input target value U _{H —} obj (k) determined in the subroutine from the high frequency control input U _{H —} cmd (k). Is calculated. The calculation is as follows.

E _L (k) = U _H _cmd (k) −U _H _obj (k)
In step S213, it computes the integral value SE _L of control error E _L (k) a (k). The calculation is as follows. Here, h represents a sampling time.

SE _L (k) = SE _L (k-1) + h * E _L (k)
In step S214, the determining at the low-band-side controller 32 the low frequency side control input U _L _cmd (k). In the present embodiment, the low-side controller 32 are the PI controller, the low-side control input U _L _cmd (k) is calculated as follows.

U _L _cmd (k) = K _pL * Etb (k) + K _iL * SEtb (k)
Here, K _pL is a proportional gain of the low frequency side controller 32, and K _iL represents an integral gain of the low frequency side controller 32. The low frequency side control input U _{L —} cmd (k) is input to the movable vane 12 in the turbine 6 of the turbocharger 4.

1 is a configuration diagram of an internal combustion engine, a turbocharger, and a control device according to a first embodiment of the present invention. FIG. 5 is a configuration diagram of an internal combustion engine, a turbocharger, and a control device according to a second embodiment of the present invention. It is a block diagram of the supercharging pressure control apparatus by the 1st and 2nd embodiment of this invention. The graph which shows the behavior of the motor input request value, the VGT input request value, and the actual supercharging pressure when the stepwise target supercharging pressure is input to the supercharging pressure control device according to the first and second embodiments of the present invention. It is. It is a flowchart of the cooperative control of the electric motor and VGT in the supercharging pressure control apparatus by the 1st and 2nd embodiment of this invention. 6 is a subroutine for determining a motor input target value in the flowchart of FIG. 5. It is a block diagram of the internal combustion engine, turbocharger, and control apparatus by the 3rd Embodiment of this invention. It is a block diagram of the internal combustion engine, turbocharger, and control apparatus by the 4th Embodiment of this invention. It is a block diagram of the supercharging pressure control apparatus by the 3rd and 4th embodiment of this invention. It is a figure which shows the control input distribution table with which a high region control input distributor is provided. It is a flowchart of the cooperative control of the electric motor and VGT in the supercharging pressure control apparatus by the 3rd and 4th embodiment of this invention. 12 is a subroutine for determining a motor input target value in the flowchart of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Internal combustion engine 2 Intake pipe 3 Exhaust pipe 4 Turbocharger 5 Compressor 6 Turbine 7 Rotating shaft 8 Electric motor 9 Supercharging pressure sensor 10 Wastegate valve 11 ECU
12 Movable vane 13 Electric compressor 15 Throttle valve 21 Motor controller 22 VGT controller 31 High frequency side controller 32 Low frequency side controller 33 High frequency control input distributor

Claims (6)

A supercharging pressure control device for an internal combustion engine,
First supercharging pressure control means for controlling the supercharging pressure using an electric motor;
Second boost pressure control means for controlling the boost pressure by a method other than the first boost pressure control means;
Supercharging pressure detecting means for detecting the actual supercharging pressure;
A target boost pressure determining means for obtaining a target boost pressure;
First control request value calculation means for calculating a first control request value that is a control input to the first boost pressure control means so that the actual boost pressure approaches the target boost pressure;
First target value determining means for determining a target value of the first control request value;
Second control request value calculation means for calculating a second control request value that is a control input to the second supercharging pressure control means so that the first control request value approaches the first target value;
A supercharging pressure control device.   2. The supercharging according to claim 1, wherein during normal operation, the first target value is set to 0, and the second control request value controls a supercharging pressure so that the first control request value converges to 0. Pressure control device.   2. The acceleration control device according to claim 1, wherein at the time of acceleration, the first target value is set to a predetermined value, and the second supercharging pressure control unit controls the supercharging pressure so that the first control request value converges to the predetermined value. Supercharging pressure control device.   The supercharging pressure control device according to claim 1, further comprising a battery for driving the electric motor, wherein the control by the first supercharging pressure control means is stopped when the state of charge of the battery is not more than a predetermined value. The first supercharging pressure control means includes a supercharger with a motor and a throttle valve,
When the actual supercharging pressure is lower than the target supercharging pressure, the control input to the supercharger with electric motor is increased as the difference between the actual supercharging pressure and the target supercharging pressure increases. Increase the boost pressure,
When the actual supercharging pressure is higher than the target supercharging pressure, the larger the difference is, the closer the throttle valve opening is set to the close side, and the actual supercharging pressure is reduced.
The supercharging pressure control device according to claim 1. The first supercharging pressure control means includes a supercharger with a motor and a throttle valve,
When the actual supercharging pressure is lower than the target supercharging pressure, the greater the difference between the actual supercharging pressure and the target supercharging pressure, the more the control input to the supercharger with motor is increased, and Set the throttle valve opening in the vicinity of full open, increase the actual boost pressure,
When the actual supercharging pressure is higher than the target supercharging pressure, the larger the difference is, the more the throttle valve opening is set to the closed side, and the control input to the motor-equipped supercharger is a predetermined value. Set near the minimum value to reduce the actual boost pressure,
The supercharging pressure control device according to claim 1.

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