JP2011069333A - Internal combustion engine having multistage supercharging system, and method for controlling the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an internal combustion engine having a multistage supercharging system and a method for controlling the same, suppressing disturbance with respect to control over intake air volume by suppressing a variation in the intake air volume caused by the opening/closing operation of an exhaust bypass valve disposed in an exhaust bypass passage bypassing a high-pressure stage turbine, in the internal combustion engine having a sequential multistage supercharging system. <P>SOLUTION: The exhaust bypass valve 7d disposed in the exhaust bypass passage 7c bypassing the high-pressure stage turbine 7b is opened/closed according to the operating condition of the internal combustion engine 1, and also control over the valve opening of the EGR valve 5a of an EGR system is temporarily corrected in conjunction with the opening/closing operation of the exhaust bypass valve 7d. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a multi-stage supercharging system internal combustion engine including a plurality of superchargers connected in series, an exhaust bypass passage provided in parallel with a high-pressure turbine, and an exhaust bypass valve provided in the exhaust bypass passage, and It relates to a control method.

  Regarding internal combustion engine supercharging, a series type multi-stage turbocharging system that uses multiple turbochargers simultaneously and multiple turbochargers with greatly different capacities are arranged in series and are appropriate for the operating conditions of the internal combustion engine There is a sequential type multi-stage supercharging system that selects a supercharger. This sequential supercharging system includes an exhaust bypass passage for bypassing exhaust gas in parallel with the high-pressure turbine, and an exhaust bypass valve provided in the exhaust bypass passage. By controlling, it has a structure that can select the turbocharger.

  By opening the exhaust bypass valve, the exhaust gas can be bypassed so as not to pass through the high-pressure turbine, and the energy of the exhaust gas can be distributed to other superchargers. Further, the exhaust bypass valve is controlled to a valve opening determined by the operating condition of the internal combustion engine.

  As an example of this multi-stage supercharging system internal combustion engine, in a multi-cylinder diesel engine equipped with one EGR device and a plurality of superchargers, in order to optimize EGR control accuracy and supercharger control, the operating conditions of the engine Accordingly, there is a control device for a multi-cylinder diesel engine configured to control by separately setting operation target values of a plurality of superchargers (see, for example, Patent Document 1).

  However, in this sequential type supercharging system internal combustion engine, when the exhaust bypass valve is opened and closed, the pressure on the exhaust side of the internal combustion engine changes abruptly. May be a disturbance to control. In other words, when the exhaust bypass valve is opened, the pressure difference corresponding to the expansion ratio of the high-pressure turbine is bypassed, so that the exhaust pressure decreases and the intake air is reduced until the turbine speed of the other stage increases and balance is achieved. The amount increases. Further, when the exhaust bypass valve is closed, the high-pressure turbine in a state where the engine speed is low becomes exhaust resistance, so the exhaust pressure rises and the intake air amount decreases until the rotation speed of the high-pressure turbine rises. Decrease. In particular, when the exhaust bypass valve is closed, there is a problem that the output torque may temporarily decrease due to a decrease in the intake air amount or an increase in the exhaust pressure.

JP 2003-120354 A

  The present invention has been made in view of the above situation, and an object of the present invention is to provide an exhaust bypass valve provided in an exhaust bypass passage that bypasses a high-pressure turbine in an internal combustion engine having a sequential multi-stage turbocharging system. An object of the present invention is to provide a multi-stage supercharging system internal combustion engine that can suppress fluctuations in the intake air amount that accompanies an opening / closing operation, and can suppress disturbance to intake air amount control, and a control method therefor.

  To achieve the above object, the multistage supercharging system internal combustion engine of the present invention is an exhaust bypass provided in an exhaust bypass passage for bypassing a high pressure turbine in an internal combustion engine having a sequential multistage supercharging system and an EGR system. A control device that opens and closes the valve in accordance with the operating state of the internal combustion engine and temporarily corrects the control of the opening degree of the EGR valve of the EGR system in conjunction with the opening and closing operation of the exhaust bypass valve. Configured. The term “temporary” means that the correction is lost when a preset time has elapsed according to the operating state of the internal combustion engine.

  According to this configuration, it is possible to suppress fluctuations in the intake air amount that are caused by a sudden change in the pressure on the exhaust side of the internal combustion engine when the exhaust bypass valve is opened and closed. Further, the fluctuation of the intake air amount becomes a disturbance in the control of the exhaust gas and the output of the internal combustion engine, but this disturbance can be reduced.

  Further, even when feedback control is used for EGR control, the control amount of the EGR valve is corrected and operated only for a temporary change at the time of switching the turbocharger without affecting the control characteristics. Thus, fluctuations in the intake air amount can be effectively suppressed.

  Note that the magnitude of the valve opening correction and the decay time of the EGR valve are adjusted according to the operating state of the internal combustion engine. The correction of the opening degree of the EGR valve when the exhaust bypass valve is opened and closed is also effective when the EGR valve is controlled by feedback based on the intake air amount, and is linked to the opening and closing operation of the exhaust bypass valve. This correction is effectively applied by adding the correction as a feed forward amount.

  Further, in the above multistage supercharging system internal combustion engine, when the control device opens the exhaust bypass valve, the controller corrects the EGR valve to be temporarily opened, and when the exhaust bypass valve is closed, If the control is performed to correct the EGR valve so that it is temporarily closed, an increase in the intake air amount is suppressed when the exhaust bypass valve is opened, and a decrease in the intake air amount is suppressed when the exhaust bypass valve is closed. By suppressing, the fluctuation | variation of the intake air amount which arises with the rapid change of the pressure by the side of the exhaust_gas | exhaustion of an internal combustion engine in the case of opening / closing operation of an exhaust bypass valve can be suppressed effectively.

  Further, in the above multistage supercharging system internal combustion engine, the control device corrects the EGR valve based on instruction opening data to the exhaust bypass valve or based on opening data of the exhaust bypass valve. If the control is configured to perform the control, the correction of the opening degree of the EGR valve can be started by an instruction to open / close the exhaust bypass valve, and the EGR valve is returned to the original opening degree as time passes thereafter. Will be able to.

  When correcting the valve opening of the EGR valve based on the instruction opening data of the exhaust bypass valve (data indicating the amount of valve opening), the EGR valve is turned on earlier than the intake air amount feedback. Because it can be operated, the intake air amount fluctuation is more initial than when the EGR valve opening is corrected based on the exhaust bypass valve opening data (actual open valve opening data). Can be more effectively suppressed.

  Further, in the multistage supercharging system internal combustion engine, when the EGR valve correction is detected as an opening / closing instruction operation to the exhaust bypass valve, according to the preset operation pattern of the EGR valve, If the control is performed to correct the valve opening, the opening of the EGR valve can be corrected relatively easily by an instruction to open and close the exhaust bypass valve.

  And the control method of the multistage supercharging system internal combustion engine of the present invention for achieving the above object is a control method of an internal combustion engine provided with a sequential type multistage supercharging system and an EGR system, and bypasses the high pressure stage turbine. The exhaust bypass valve provided in the exhaust bypass passage is opened / closed according to the operating state of the internal combustion engine, and temporarily controlled to control the valve opening of the EGR valve of the EGR system in conjunction with the opening / closing operation of the exhaust bypass valve. This is a method of adding correction to the above.

  According to this method, when the exhaust bypass valve is opened and closed, fluctuations in the intake air amount that occur with a sudden change in the pressure on the exhaust side of the internal combustion engine can be suppressed. Further, the fluctuation of the intake air amount becomes a disturbance in the control of the exhaust gas and the output of the internal combustion engine, but this disturbance can be reduced.

  In the control method for the multi-stage supercharging system internal combustion engine, when the exhaust bypass valve is opened, the EGR valve is temporarily corrected to be on the open side, and when the exhaust bypass valve is closed, the EGR valve is corrected. If the exhaust bypass valve is opened, opening and closing of the exhaust bypass valve is suppressed by suppressing the increase of the intake air amount when opening the exhaust bypass valve and suppressing the decrease of the intake air amount when closing the exhaust bypass valve. It is possible to effectively suppress fluctuations in the intake air amount that occur with a sudden change in pressure on the exhaust side of the internal combustion engine during operation.

  Further, in the above-described multistage supercharging system internal combustion engine control method, when the EGR valve is corrected based on the instruction opening data to the exhaust bypass valve or based on the opening data of the exhaust bypass valve. Then, the correction of the valve opening of the EGR valve can be started by an instruction to open and close the exhaust bypass valve, and control can be performed so that the EGR valve is returned to the original valve opening with the passage of time thereafter.

  Further, in the control method of the multistage supercharging system internal combustion engine, when the EGR valve correction is detected as an opening / closing instruction operation to the exhaust bypass valve, according to a preset operation pattern of the EGR valve, When the opening degree of the EGR valve is corrected, the opening degree of the EGR valve can be corrected relatively easily by an opening / closing instruction of the exhaust bypass valve.

  According to the multistage supercharging system internal combustion engine and the control method therefor according to the present invention, when the exhaust bypass valve is opened and closed, the fluctuation of the intake air amount caused by the rapid change in the pressure on the exhaust side of the internal combustion engine is suppressed. The disturbance in the control of the exhaust gas and the output of the internal combustion engine can be reduced by suppressing the fluctuation of the intake air amount.

  That is, it is possible to suppress the switching operation of the supercharger from being a disturbance of the intake air amount control. Thereby, the fluctuation of the output of the internal combustion engine due to the fluctuation of the intake air amount can be reduced.

It is the figure which showed the structure of the multistage supercharging system internal combustion engine of embodiment which concerns on this invention. It is the figure which showed the outline | summary of control of the multistage supercharging system internal combustion engine of embodiment which concerns on this invention. It is the figure which showed the outline | summary of another example of control of the multistage supercharging system internal combustion engine of embodiment which concerns on this invention. It is the figure which showed the effect of control.

  Hereinafter, a supercharging system internal combustion engine and a control method thereof according to embodiments of the present invention will be described with reference to the drawings.

  As shown in FIG. 1, a supercharging system internal combustion engine (hereinafter referred to as an internal combustion engine) 1 according to an embodiment of the present invention is provided with an intake passage 3, an exhaust passage 4 and an EGR passage 5 in an engine body (E) 2. The low-pressure stage compressor 6a of the low-pressure stage supercharger 6 and the high-pressure stage compressor 7a of the high-pressure stage supercharger 7 are arranged in series from the upstream side of the intake passage 3 and the high-pressure stage The high-pressure turbine 7b of the feeder 7 and the low-pressure turbine 6b of the low-pressure supercharger 6 are arranged in series.

  The high-pressure turbine 7b is provided with an exhaust bypass passage 7c that bypasses the high-pressure turbine 7b, and further, an exhaust bypass valve 7d is provided in the exhaust bypass passage 7c. An intake bypass passage 7e that bypasses the high-pressure compressor 7a is provided, and an intake bypass valve 7f is provided in the intake bypass passage 7e. The low-pressure turbine 6b is provided with a waste gate valve 6c. With these configurations, a sequential type two-stage supercharging system is formed.

  The EGR passage 5 is provided with an EGR valve 5a. The intake passage 3 is provided with an intake air amount sensor (MAF sensor) (not shown). Further, a control device (ECU) 8 called an ECU (Engine Control Unit) for controlling the operating state of the engine of the internal combustion engine 1 and the EGR valve 5a and the exhaust bypass valve 7d is provided.

  Note that an air cleaner, an intake throttle valve, an intercooler, an EGR cooler, an exhaust gas purifier, an exhaust throttle valve, a silencer, and the like that are not directly related to the present invention are also provided, but are not shown for the sake of simplicity.

  Next, as shown in FIGS. 2 and 3 for explaining a control method in the internal combustion engine 1, in the internal combustion engine 1, an exhaust bypass valve 7d provided in an exhaust bypass passage 7c that bypasses the high-pressure turbine 7 is provided with an internal combustion engine. The opening / closing operation is performed in accordance with the operating state of the engine 1, and the control of the valve opening degree of the EGR valve 5a of the EGR system is temporarily corrected in conjunction with the opening / closing operation of the exhaust bypass valve 7d. The term “temporary” means that the correction is lost after a preset time has elapsed according to the operating state of the internal combustion engine.

  As shown in FIGS. 2 and 3, the correction of the valve opening is an instruction opening that is instruction opening data to the exhaust bypass valve 7d (instructs the valve opening of the instruction opening data). Based on Vbt, when the exhaust bypass valve 7d is opened, the EGR valve 5a is corrected to be temporarily open, and when the exhaust bypass valve 7d is closed, the EGR valve 5a is temporarily closed. to correct.

  Alternatively, although not particularly illustrated, when the exhaust bypass valve 7d is opened based on the opening data of the exhaust bypass valve 7d (valid opening data), the EGR valve 5a is temporarily opened. When the exhaust bypass valve 7d is closed, the EGR valve 5a is temporarily corrected to be on the closing side.

  When the valve opening of the EGR valve 5a is corrected based on the instruction opening data of the exhaust bypass valve 7d, the EGR valve 5a can be operated at a timing earlier than the intake air amount feedback. Compared with the case where the opening degree of the EGR valve 5a is corrected based on the opening degree data of the valve 7d, the initial behavior of the intake air amount fluctuation can be suppressed more effectively.

  In the case shown in FIG. 2, in the normal case, the valve opening of the EGR valve 5a is determined from the engine speed Ne and the fuel injection amount Q by referring to the map M1 of “valve opening data of the EGR valve”. In the case of the loop, the instruction opening degree Vet1 of the EGR valve 5a is set, and in the case of feedback, the instruction opening degree Vet2 of the EGR valve 5a is set.

  When correction is made based on the opening degree data to the exhaust bypass valve 7d, as shown in FIG. 2, the instruction opening degree data Vbt of the exhaust bypass valve 7d, the engine speed Ne, and the fuel injection amount Q are From the magnitude of the correction amount obtained by referring to the gain map M2 of the “EGR valve opening correction data”, the engine speed Ne and the fuel injection amount Q, the “EGR valve opening correction data” A time constant for attenuating the correction amount obtained by referring to the constant map M3 is input to a control circuit having a high-pass filter. By using this high-pass filter, it is possible to easily detect the opening / closing timing of the exhaust bypass valve 7d.

  Based on the data processed by the control circuit, if the control for correcting the EGR valve 5a (the magnitude of the correction amount (gain) and the degree of attenuation (time constant)) is performed, an instruction to open / close the exhaust bypass valve 7a is given. Based on the data, it is possible to start control of the opening of the EGR valve 5a according to the magnitude (gain) of the correction amount, and the EGR valve 5a is opened as time passes thereafter according to the degree of attenuation (time constant). You can control to return to the degree.

  The magnitude (gain) and the decay time (time constant) of the correction amount of the valve opening degree of the EGR valve 5a are adjusted according to the operating state of the internal combustion engine 1, but the adjustment amount (gain and time constant) is calculated. Is performed by referring to the gain map M2 and the time constant map M3 from the engine speed Ne and the fuel injection amount Q, respectively.

  The correction of the valve opening degree of the EGR valve 5a when the exhaust bypass valve 7d is opened and closed is effective even when the EGR valve 5a is controlled by feedback based on the intake air amount. It works effectively by adding a correction linked to the feed forward amount.

  In the case shown in FIG. 3, when the opening / closing instruction operation to the exhaust bypass valve 7d is detected, the opening degree of the EGR valve 5a is corrected by the data table M4 of the EGR correction operation pattern set in advance. The amplitude of the correction pattern is determined by the correction gain obtained from the gain map M2 based on the engine speed Ne and the fuel injection amount Q. The determined correction pattern is added to the EGR valve opening degree map M1 data and used for valve opening degree control of the EGR valve 5a.

  With such a configuration, the correction operation of the valve opening degree of the EGR valve 5a can be performed relatively easily based on a predetermined correction operation pattern.

  Next, experimental results when the EGR valve correction control is not performed and when it is performed will be described. As shown in FIG. 4, it can be seen that when the EGR valve 5a is corrected (solid line A), the amount of fluctuation in the intake air amount is smaller than when the correction control is not performed (dotted line B).

  Therefore, according to the internal combustion engine 1 and the control method thereof configured as described above, when the exhaust bypass valve 7d is opened by the control by the correction of the EGR valve 5a, an increase in the intake air amount is suppressed, and when the exhaust bypass valve 7d is closed, By suppressing the decrease in the intake air amount, it is possible to effectively suppress fluctuations in the intake air amount caused by a sudden change in the pressure on the exhaust side of the internal combustion engine 1 when the exhaust bypass valve 7d is opened and closed. . The fluctuation of the intake air amount becomes a disturbance in the control of the exhaust gas and the control of the output of the internal combustion engine 1, but this disturbance can be reduced.

  Further, even when feedback control is used for EGR control, the control amount of the EGR valve 5a is corrected and corrected only for temporary fluctuations at the time of turbocharger switching without affecting the control characteristics. By doing so, fluctuations in the intake air amount can be effectively suppressed.

  According to the multistage supercharging system internal combustion engine of the present invention and the control method thereof, in the sequential type multistage supercharging system internal combustion engine, when the exhaust bypass valve provided in the exhaust bypass passage for bypassing the high pressure turbine is opened and closed, It is possible to suppress fluctuations in the intake air amount caused by a sudden change in the pressure on the exhaust side of the internal combustion engine. By suppressing the fluctuations in the intake air amount, control of exhaust gas and output of the internal combustion engine Therefore, it can be used for an internal combustion engine mounted on an automobile.

1 Supercharging System Internal Combustion Engine 2 Engine Body (E)
5a EGR valve 7b High-pressure turbine 7c Exhaust bypass passage 7d Exhaust bypass valve 8 Control device (ECU)
Ne Engine speed M1 “EGR valve opening data” map M2 “EGR valve opening correction data” gain map M3 “EGR valve opening correction data” time constant map M4 “EGR Data table of “valve correction operation pattern” Q Fuel injection amount Vbt Indication opening to exhaust bypass valve Vet1, Vet2 Indication opening of EGR valve

Claims (6)

  In an internal combustion engine having a sequential type multi-stage turbocharging system and an EGR system, an exhaust bypass valve provided in an exhaust bypass passage for bypassing the high-pressure turbine is opened and closed in accordance with the operating state of the internal combustion engine, and the exhaust A multistage supercharging system internal combustion engine comprising a control device that temporarily corrects the control of the opening degree of an EGR valve of an EGR system in conjunction with opening and closing operations of a bypass valve.   The controller corrects the EGR valve to be temporarily opened when the exhaust bypass valve is opened, and temporarily closes the EGR valve when the exhaust bypass valve is closed. The multistage supercharging system internal combustion engine according to claim 1, wherein correction control is performed.   Control by which the control device corrects the EGR valve based on the instruction opening data to the exhaust bypass valve or based on data obtained by processing the opening data of the exhaust bypass valve with a high-pass filter The multistage supercharging system internal combustion engine according to claim 1 or 2, wherein   In a control method for an internal combustion engine provided with a sequential type multi-stage turbocharging system and an EGR system, an exhaust bypass valve provided in an exhaust bypass passage for bypassing a high-pressure turbine is opened and closed in accordance with the operating state of the internal combustion engine. A control method for a multi-stage supercharging system internal combustion engine, characterized in that a correction is temporarily made in the control of the opening degree of the EGR valve of the EGR system in conjunction with the opening / closing operation of the exhaust bypass valve.   When opening the exhaust bypass valve, the EGR valve is corrected to temporarily open, and when the exhaust bypass valve is closed, the EGR valve is corrected to temporarily close. The control method of the multistage supercharging system internal combustion engine according to claim 4.   The correction of the EGR valve is performed based on the instruction opening data to the exhaust bypass valve or based on data obtained by processing the opening data of the exhaust bypass valve with a high-pass filter. Item 6. The method for controlling a multistage supercharging system internal combustion engine according to Item 4 or 5.

Images