JP6913624B2 - Internal combustion engine control method - Google Patents

Description

The present invention relates to a control device for an internal combustion engine that controls combustion of an air-fuel mixture in a combustion chamber, and in particular, increases the density of air taken in by the internal combustion engine by driving a compressor using the energy of exhaust gas. It relates to a control device for an internal combustion engine equipped with a turbocharger and a control method thereof.

In recent internal combustion engines with a supercharger, the amount of exhaust energy recovered and the amount of compressed air are adjusted in order to control the boost pressure in the supercharged region. A system that utilizes the energy of exhaust gas to increase the density of intake air (hereinafter referred to as a supercharging system) is described in, for example, Japanese Patent Application Laid-Open No. 2006-299859 (Patent Document 1). There is.

Patent Document 1 describes a control device for an internal combustion engine including a turbocharger (supercharger), and bypasses the turbocharger (supercharger) turbine of the engine exhaust system when the boost pressure exceeds the upper limit value. Open the wastegate valve located in the wastegate passage, and open the air bypass valve located in the air bypass passage that bypasses the turbocharger (supercharger) compressor on the upstream side of the throttle valve in the engine intake system. It is described that the valve is opened to control the upper limit of the boost pressure.

Japanese Unexamined Patent Publication No. 2006-299859

By the way, in the supercharger described in Patent Document 1, not only the wastegate valve is opened but also the air bypass valve is opened in controlling the upper limit value of the supercharging pressure in the high supercharging region. When the boost pressure exceeds the upper limit, it is necessary to open the wastegate valve to suppress the turbine speed, but by itself, the boost pressure overshoots due to the response delay, so the air bypass valve is used. The valve is opened to suppress the overshoot of the boost pressure.

On the other hand, in the low supercharging region, that is, in the region where the differential pressure upstream and downstream of the compressor is small and the mechanical wastegate valve is not operating, the supercharging pressure is determined by the characteristics of the supercharger. Further, since the supercharging pressure in the low supercharging region does not exceed the upper limit value, the air bypass valve is always closed. Therefore, with the method as in Patent Document 1, accurate supercharging pressure cannot be realized in the low supercharging region, and there is a possibility that the target torque cannot be generated accurately.

Therefore, an object of the present invention is a novel internal combustion engine control device capable of accurately generating a target torque of the internal combustion engine even in a low supercharging region in an internal combustion engine provided with a supercharger, and a control method thereof. Is to provide.

Further, the present invention requires the driver based on (a) a step of reading an input value including at least the amount of depression of the accelerator pedal and the number of rotations of the internal combustion engine, and (b) the input value read in the step (a). The step of calculating the target torque and the target intake fresh air flow rate and calculating the target intake pipe pressure based on it, and (c) the actual intake pipe pressure estimated from the actual intake pipe pressure detected by the sensor or the amount of air taken in from the outside are When it is determined in the step of determining whether or not the pressure is equal to or higher than the atmospheric pressure and (d) in the step (c) above, the actual intake pipe pressure is determined to be equal to or higher than the atmospheric pressure. When it is determined in the step of determining whether or not the operating pressure is equal to or higher than the operating pressure and (e) in the step (d), when it is determined that the actual intake pipe pressure is equal to or less than the operating pressure of the predetermined waste gate valve, the actual intake pipe It has a step of determining whether or not the difference between the pressure and the target intake pipe pressure is equal to or more than a predetermined value, and in the step (e), the difference between the actual intake pipe pressure and the target intake pipe pressure is predetermined. When it is determined that the value is equal to or more than the value, the air bypass valve is controlled to be opened, and when it is determined to be equal to or less than the predetermined value, the air bypass valve is controlled to be closed.

According to the present invention, since the air bypass valve opening degree is set based on the difference between the target intake pipe pressure and the actual intake pipe pressure, the target torque can be generated accurately even in the low supercharging region.

This makes it possible to improve the fuel efficiency of the internal combustion engine and the durability and reliability of external devices such as transmissions.

Issues, configurations and effects other than those described above will be clarified by the description of the following embodiments.

It is a block diagram of the internal combustion engine provided with the supercharging system which concerns on one Embodiment of this invention. It is a block diagram which shows the control block of the air bypass valve control device which concerns on one Embodiment of this invention. It is a figure which shows the problem in the case of controlling the intake pipe pressure by using a wastegate valve in a low supercharging region. It is a figure which shows the effect when the intake pipe pressure is controlled by using an air bypass valve in a low supercharging region. It is a flowchart which shows the control flow of the air bypass valve control device which concerns on one Embodiment of this invention. It is a control block diagram which shows the switching mechanism of the air bypass valve control and wastegate valve control which concerns on one Embodiment of this invention. It is a flowchart which shows the control flow of the air bypass valve control device which concerns on one Embodiment of this invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In each drawing, the same components are designated by the same reference numerals, and the detailed description of overlapping portions will be omitted. Further, the present invention is not limited to the following embodiments, and various modifications and applications are included in the technical concept of the present invention.

The control device and control method for the internal combustion engine of the first embodiment will be described with reference to FIGS. 1 to 5. FIG. 1 shows the configuration of an internal combustion engine including a supercharger to which the present invention is applied. A supercharger 12 and a pre-catalyst 13 are installed in the piping of the exhaust passage 11 of the internal combustion engine 10. The supercharger (compressor) 12 utilizes a turbine that rotates in response to the flow of exhaust gas, a waste gate valve 33 that divides the exhaust gas that passes through the turbine, a shaft that transmits the rotation of the turbine, and rotation torque of the turbine. It is composed of a compressor that takes in air and compresses it, and an air bypass valve 34 that divides the air that passes through the compressor, and the internal combustion engine 10 sucks in by driving the compressor using the flow of exhaust gas. It has a supercharging function that increases the air density of the intake gas. The supercharger (compressor) 12 rotates integrally with the turbine, compresses the air on the engine exhaust side, and supplies it to the engine intake side. The wastegate valve 33 opens and closes the exhaust side bypass passage that bypasses the turbine, and the air bypass valve 34 opens and closes the intake side bypass passage that bypasses the compressor.

The exhaust gas from the internal combustion engine 10 is purified by reduction and oxidation in the pre-catalyst 13 and the main catalyst 14. Particulate matter that cannot be purified by the pre-catalyst 13 and the main catalyst 14 is purified by a particulate filter (GPF: Gasoline Particulate Filter) 15.

A part of the exhaust gas purified by the pre-catalyst 13 is taken into the EGR pipe 16 from the downstream of the pre-catalyst 13, cooled by the gas cooler 17, and returned to the upstream of the supercharger 12. The upstream of the supercharger 12 is a portion where the intake gas flows into the supercharger 12. A part of the combustion gas generated in the combustion cylinder 18 of the internal combustion engine 10 is returned to the intake passage 19 via the EGR pipe 16 and mixed with the intake fresh air newly sucked from the outside through the air cleaner 20. NS. An intercooler 31 is arranged in the intake passage 19 downstream of the supercharger 12.

The air cleaner 20 removes dust and the like contained in the inhaled fresh air to be inhaled. The flow rate of the EGR gas recirculated from the EGR pipe 16 is determined by controlling the opening degree of the EGR valve 21. By controlling the EGR gas, the combustion temperature of the air-fuel mixture in the combustion cylinder 18 can be lowered, the amount of NOx emissions can be reduced, and the pump loss can be further reduced. Further, the differential pressure sensor 22 attached so as to straddle the EGR valve 21 detects the difference (differential pressure) between the pressure on the front side (upstream side) and the pressure on the rear side (downstream side) of the EGR valve 21. ..

The internal combustion engine 10 is controlled by a control device (ECU: Engine Control Unit) 23. The air flow rate sensor 24 detects the flow rate of newly sucked fresh air from the outside. Further, a pressure sensor 32 is attached between the supercharger 12 and the combustion cylinder 18 to detect the pressure in the intake passage 19 leading to the combustion cylinder 18 or the intake collector 26 downstream of the throttle valve 25. The flow rate of the intake gas flowing from the intake passage 19 to the combustion cylinder 18 is controlled by the variable phase valve timing mechanism 27 that changes the opening degree of the throttle valve 25 or the opening / closing timing of the intake valve or the exhaust valve.

The control device 23 of the present embodiment has at least a target required torque (hereinafter referred to as a target torque) required by the driver detected by the accelerator pedal sensor 28 and a rotation speed detected by the rotation speed sensor 29. Based on the above, the actuator (electric motor) of the throttle valve 25 and the actuator (mechanical stroke) of the waste gate valve 33 of the supercharger 12 are controlled so as to realize the target intake gas amount. Further, the control device 23 realizes a target EGR rate (Exhaust Gas Recirculation) based on the detection value of the pressure sensor 32, the opening degree of the throttle valve 25, or the detection value of the air flow sensor 24. The actuators (electric motors) of the EGR valve 21 and the throttle valve 25 are controlled so as to do so.

In the present embodiment, the EGR rate refers to the ratio of the flow rate of the intake fresh air and the EGR gas to the intake gas flowing through the intake passage 19. Then, the control device 23 detects the difference (differential pressure) between the pressure on the front side (upstream side) and the pressure on the rear side (downstream side) of the EGR valve 21 by the differential pressure sensor 22, and based on this, the EGR valve 21 and the throttle The opening degree of the valve 25 or the phase angle of the intake / exhaust valve is set by the variable phase valve timing mechanism 27 to control the EGR rate of the intake gas flowing into the combustion cylinder 18. Further, the control device 23 optimally controls the ignition timing of the spark plug 30 so as not to cause knocking and to maximize the output of the internal combustion engine 10.

Next, the control block of the control device of this embodiment will be described with reference to FIG. FIG. 2 shows a control block of a control unit (CPU: Central Processing Unit) 35 provided in a control device (ECU) 23.

In this embodiment, the control device (ECU) 23 refers to the entire control device as an engine control unit, and the control unit (CPU) 35 is the center (calculation) of a semiconductor device or the like incorporated in the control device (ECU) 23. Refers to a processing unit.

The control unit (CPU) 35 includes a target torque calculation unit 40, a target intake fresh air flow rate calculation unit 41, a target EGR rate calculation unit 42, a throttle passing EGR gas flow rate calculation unit 43, a target throttle intake gas flow rate calculation unit 44, and a target throttle. Valve opening degree calculation unit 45, target throttle upstream / downstream environment calculation unit 49, target waste gate valve opening degree calculation unit 51, target air bypass valve opening degree calculation unit 52, target EGR gas flow rate calculation unit 46, and target EGR valve opening degree It is composed of a calculation unit 47.

Next, these specific functions will be described. In the target torque calculation unit 40, the internal combustion engine 10 outputs based on the depression amount θacc detected by the accelerator pedal sensor 28 representing the target torque required by the driver and the rotation speed Ne detected by the rotation speed sensor 29. The target torque Trq to be calculated is calculated. This target torque Trq may be obtained by an arithmetic expression, or may be obtained by a map from the rotation speed Ne and the stepping amount θacc. In this embodiment, a map search method is adopted in order to increase the calculation speed. The obtained target torque Trq is sent to the target intake fresh air flow rate calculation unit 41.

In the target suction fresh air flow rate calculation unit 41, the target intake fresh air that realizes the target torque Trq obtained by the target torque calculation unit 40 based on the rotation speed Ne and the target torque Trq detected by the rotation speed sensor 29. Calculate the flow rate Qattrgt. In this case as well, the target intake fresh air flow rate Qattrgt may be obtained by an arithmetic expression, or may be obtained from the rotation speed Ne and the target torque Trq by a map. In this embodiment, a map search method is adopted in order to increase the calculation speed. The obtained target intake fresh air flow rate Qattrgt is sent to the target throttle intake gas flow rate calculation unit 44 and the target EGR gas flow rate calculation unit 46, which will be described later.

The target EGR rate calculation unit 42 calculates the target EGR rate Regr based on the rotation speed Ne and the target torque Trq detected by the rotation speed sensor 29. The target EGR rate Regr may be obtained by an arithmetic expression, or may be obtained by a map from the rotation speed Ne and the target torque Trq. In this embodiment, a map search method is adopted in order to increase the calculation speed. The obtained target EGR rate Regr is sent to the target EGR gas flow rate calculation unit 46, which will be described later.

In the throttle-passing EGR gas flow rate calculation unit 43, the air amount Qa detected by the air flow rate sensor 24, the opening degree θegr of the EGR valve 21, and the differential pressure detected by the differential pressure sensor 22 attached so as to straddle the EGR valve 21. Based on Pegr, the opening degree θth of the throttle valve 25, the rotation speed Ne detected by the rotation speed sensor 29, and the like, the flow amount of EGR gas from the EGR valve 21 to the throttle valve 25 is determined by the EGR valve 21. It is calculated in consideration of the operation delay time (waste time) and the flow delay time due to the passage lengths of the EGR pipe 16 and the intake passage 19, and finally the throttle passing EGR gas flow rate Qthegr passing through the throttle valve 25 is estimated. The estimation of the EGR gas flow rate Qthegr passing through the throttle can be performed by, for example, the following method.

First, a calculation area divided into two, upstream and downstream of the throttle valve 25, is set. Then, the EGR gas flow rate passing through the EGR valve is calculated from the differential pressure of the differential pressure sensor 22 attached so as to straddle the EGR valve 21 and the opening degree of the EGR valve 21. Next, the intake fresh air flow rate is detected using the air flow rate sensor 24. Further, the EGR gas flow rate passing through the EGR valve and the intake fresh air flow rate are totaled to calculate the compressor passing gas flow rate of the turbocharger 12 and the EGR rate.

Then, the pressure, temperature, and mass in the upstream region of the throttle valve 25 are calculated using the flow rate of the gas passing through the compressor and the flow rate of the throttle suction gas passing through the throttle valve 25 calculated in the previous calculation cycle, and based on this, this time. Calculates the flow rate of throttle intake gas passing through the throttle valve 25 in the calculation cycle of. Finally, the throttle intake gas flow rate of the throttle valve 25 in the current calculation cycle and the EGR rate calculated in the previous calculation cycle are used to calculate the throttle passing EGR gas flow rate Qthegr passing through the throttle valve 25.

The estimation of the throttle passing EGR gas flow rate Qthegr can be obtained by constructing the above-mentioned physical model, but the physical model is arbitrary, in short, the throttle passing EGR gas flow rate Qthegr passing through the throttle valve 25 is estimated. It would be nice if it could be done. The obtained throttle passing EGR gas flow rate Qthegr is sent to the target throttle intake gas flow rate calculation unit 44.

In the target throttle intake gas flow rate calculation unit 44, from the target intake fresh air flow rate Qattrg obtained by the target intake fresh air flow rate calculation unit 41 and the throttle passing EGR gas flow rate Qthegr obtained by the throttle passing EGR gas flow rate calculation unit 43. , The target throttle intake gas flow rate Qgth passing through the throttle valve 25 is calculated using the following equation (1).

Then, the obtained target throttle intake gas flow rate Qgth is sent to the target throttle valve opening degree calculation unit 45.

In the target throttle valve opening degree calculation unit 45, the electric motor for driving the throttle valve 25 is calculated by calculating the target throttle valve opening degree θthtrgt from the target throttle intake gas flow rate Qgth calculated by the target throttle intake gas flow rate calculation unit 44. Control. In this case as well, the target throttle opening degree θthtrgt may be obtained by an arithmetic expression, or may be obtained from the target throttle intake gas flow rate Qgth by a map. In this embodiment, a map search method is adopted in order to increase the calculation speed.

In the target throttle upstream / downstream environment calculation unit 49, at least the target target temperature upstream of the throttle valve 25 is based on the target intake fresh air flow rate Qattrgt and the rotation speed Ne calculated by the target intake fresh air flow rate calculation unit 41. The TT _up , the target supercharging pressure TP _up , and the target intake pipe pressure TP _dn downstream of the throttle valve 25 are calculated. The target temperature TT _up , the target supercharging pressure TP _up , and the target intake pipe pressure TP _dn described above can be obtained by other methods instead of the target intake fresh air flow rate Qattrgt.

_{The target wastegate valve opening degree calculation unit 51 sets the target supercharging pressure TP up} or the target intake pipe pressure TP _dn upstream of the throttle valve 25 obtained by the target throttle upstream / downstream environment calculation unit 49. Based on this, the target wastegate valve opening degree θwgtrgt is calculated. The target wastegate valve opening degree θwgtrgt may be obtained by an arithmetic expression _, or may be obtained from the target supercharging pressure TP up or the target intake pipe pressure TP _dn by a map.

_{The target air bypass valve opening degree calculation unit 52 sets the target supercharging pressure TP up} or the target intake pipe pressure TP _dn upstream of the throttle valve 25 obtained by the target throttle upstream / downstream environment calculation unit 49. Based on this, the target air bypass valve opening degree θabtrgt is calculated. The target air bypass valve opening degree θabtrgt may be obtained by an arithmetic expression _, or may be obtained from the target supercharging pressure TP up or the target intake pipe pressure TP _dn by a map.

The target EGR gas flow rate calculation unit 46 is based on the target intake fresh air flow rate Qattrg obtained by the target intake fresh air flow rate calculation unit 41 and the target EGR rate Regr obtained by the target EGR rate calculation unit 42, and the following (2). The target EGR gas flow rate Qegr is calculated using the formula.

The obtained target EGR gas flow rate Qegr is sent to the target EGR valve opening degree calculation unit 47.

The target EGR valve opening degree calculation unit 47 calculates the target EGR valve opening degree θegrtrgt from the target EGR gas flow rate Qegr calculated by the target EGR gas flow rate calculation unit 46, and controls the electric motor that drives the EGR valve 21. .. In this case as well, the target EGR valve opening degree θegrgt may be obtained by an arithmetic expression, or may be obtained from the target EGR gas flow rate Qegr by a map. In this embodiment, a map search method is adopted in order to increase the calculation speed.

With the above configuration, in the supercharging system of the present embodiment, the target air bypass valve opening degree θabtrgt is obtained in the low supercharging region based on the target supercharging pressure TP _up or the target intake pipe pressure TP _dn. be able to. As a result, the target intake pipe pressure TP _dn can be realized, and the target torque can be generated with high accuracy.

Next, the actions and effects when the present embodiment is implemented will be described. FIG. 3 shows the target throttle valve opening degree θthtrgt and the target wastegate valve opening degree θwgtrgt for achieving the target intake pipe pressure TP _{dn, and three turbochargers having different flow rates (large-flow turbocharger,} The realization accuracy of _{the target intake pipe pressure TP dn} of the master product (small flow rate turbocharger) is shown.

As shown in FIG. 3, when the target intake pipe pressure TP _dn is equal to or lower than the atmospheric pressure, the target intake pipe pressure TP _dn is realized by adjusting the opening degree of the throttle valve 25. When the target intake pipe pressure TP _dn is equal to or higher than the atmospheric pressure, the throttle valve 25 is substantially fully opened and the wastegate valve 33 is used to control the _{target intake pipe pressure TP dn in order to reduce the pump loss.} However, in the region where the difference between the target supercharging pressure TP _up and the atmospheric pressure is small, that is, in the low supercharging region, the differential pressure for operating the wastegate valve 33 is insufficient.

Therefore, in this state, the wastegate valve 33 is always closed, and the _{accuracy of achieving the target intake pipe pressure TP dn} deteriorates due to the variation in the flow rate of the turbocharger. For example, compared to the master product that can realize the target intake pipe even when the wastegate valve 33 is closed, the intake pipe pressure realized by the large-flow turbocharger becomes excessive as shown in FIG. 3, and the small-flow supercharger is realized. The intake pipe pressure is too low as shown in FIG. As a result, a phenomenon occurs in which the actual generated torque (actual torque) becomes excessive or too small with respect to the target torque.

When the above-mentioned excess and under pressure of the actual intake pipe occurs, the control accuracy of the generated torque deteriorates, and in some cases, the durability and reliability of the product deteriorate due to damage to the transmission or the like. ..

_{On the other hand, in the present embodiment, the difference between the target intake pipe pressure TP dn} and the actual intake pipe pressure P _dn calculated by the target throttle upstream / downstream environment calculation unit 49 in the set low supercharging region is the set value. In the above cases, since the target air bypass valve opening degree θabtrgt is controlled, it is possible to improve the excess and the excess of the actual intake pipe pressure.

As shown in FIG. 4, when the low supercharging region becomes atmospheric pressure or higher, the differential pressure for operating the wastegate valve 33 is insufficient, so that the wastegate valve 33 is always closed. In the low supercharging region, the small flow rate turbocharger needs to increase the passing flow rate of the compressor in order to achieve the _{target intake pipe pressure TP dn like the master product.} That is, the target air bypass valve opening degree θabtrgt is set to a value smaller than that of the master product, and the air bypass valve 34 is controlled to be closed. That is, the larger the target supercharging pressure TP _{up, the} smaller the opening degree of the air bypass valve 34 is controlled.

On the other hand, unlike the master product, the large flow rate turbocharger needs to reduce the passing flow rate of the compressor in order to achieve the _{target intake pipe pressure TP dn.} That is, the target air bypass valve opening degree θabtrgt is set to a value larger than that of the master product, and the air bypass valve 34 is controlled to be opened.

As described above, according to the present embodiment, when the throttle valve 25 is fully opened and the wastegate valve 33 is closed, the actual intake pipe pressure is set to the target intake pipe pressure TP _{dn by controlling the opening and closing of the air bypass valve 34.} It is possible to suppress the phenomenon of being excessive or too small, and it is possible to improve the control accuracy of the generated torque.

Next, the control flow of the air bypass valve control device of the present embodiment described above will be briefly described with reference to FIG. This control flow indicates control when the air bypass valve 34 is switched from the valve closed state to the valve open state, and is repeatedly executed at predetermined start timings.

<< Step S40 >>
First, in step S40, the amount of air Qa required for the physical model for estimating the actual intake pipe pressure, the actual intake pipe pressure Pm, the target air bypass valve opening degree θabtrgt, the target wastegate valve opening degree θwgtrgt, and the throttle are performed by various sensors. Read the valve opening θth, the number of revolutions Ne, the atmospheric pressure Patm, the accelerator pedal opening θacc, and the like. When the input required for the physical model is read, the process proceeds to step S41.

≪Step S41≫
Next, in step S41, the target torque Trq and the target intake fresh air flow rate Qattrg required by the driver are calculated from the accelerator pedal opening θacc based on the read input, and the target intake pipe pressure TP _dn is calculated based on the target torque Trq and the target intake fresh air flow rate Qattrgt. .. When the target intake pipe pressure TP _dn is obtained, the process proceeds to step S42.

<< Step S42 >>
Subsequently, in step S42, it is determined whether or not the actual intake pipe pressure Pm detected from the intake pipe pressure or the actual intake pipe pressure Pm estimated from the air amount Qa is equal to or higher than the atmospheric pressure Patm. If it is above the atmospheric pressure Patm, the process proceeds to step S43, and if it is below the atmospheric pressure Patm, the return is exited and the next start timing is waited for.

≪Step S43≫
In step S43, it is determined whether or not the actual intake pipe pressure Pm obtained in step S42 is equal to or higher than the operating pressure Pwg of the predetermined wastegate valve 33. If the working pressure is Pwg or less, the process proceeds to step S44, and if the working pressure is Pwg or more, the return is performed and the next start timing is waited.

<< Step S44 >>
In step S44, it is determined whether or not the difference (Pm-TP _dn ) between the actual intake pipe pressure Pm obtained in step S42 and the target intake pipe pressure TP _dn obtained in step S41 is equal to or greater than a predetermined value. If it is equal to or more than a predetermined value, the target air bypass valve opening degree θabtrgt (air bypass valve 34) is controlled to be opened. If it is equal to or less than a predetermined value, the target air bypass valve opening degree θabtrgt (air bypass valve 34) is controlled to be closed. After that, it goes out to the return and waits for the next start timing.

As described above, according to the present embodiment, since the intake pipe pressure is controlled by using the air bypass valve 34 instead of the throttle valve 25, it is caused by the loss of the throttle valve 25 even in the low supercharging region. There is no increase in exhaust pressure, and pump loss can be reduced. That is, fuel efficiency can be improved. Further, since the target torque can be generated with high accuracy even in the low supercharging region, the durability and reliability of an external device such as a transmission can be improved.

Next, a control device and a control method for the internal combustion engine of the second embodiment will be described with reference to FIGS. 6 and 7. FIG. 6 is a control block diagram showing a switching mechanism between air bypass valve control and wastegate valve control.

As shown in FIG. 6, the present embodiment is different from the first embodiment in that the wastegate valve 33 is controlled to be opened and the air bypass valve 34 is closed in the high supercharging region after the low supercharging region. .. The actual intake pipe pressure Pm and the operating pressure of the waste gate valve 33 are input to determine whether it is in the low supercharging region or the high supercharging region, and based on the determination result, air bypass valve control and waste gate valve control are performed. By switching between, feedback (FB) control of the intake pipe pressure based on the actual intake pipe pressure Pm and the target intake pipe pressure TP _{dn is performed.}

The control flow of the air bypass valve control device of the present embodiment will be briefly described with reference to FIG. 7.

<< Step S50 >>
First, in step S50, the amount of air Qa required for the physical model for estimating the actual intake pipe pressure, the actual intake pipe pressure Pm, the target air bypass valve opening degree θabtrgt, the target wastegate valve opening degree θwgtrgt, and the throttle are performed by various sensors. Read the valve opening θth, the number of revolutions Ne, the atmospheric pressure Patm, the accelerator pedal opening θacc, and the like. When the input required for the physical model is read, the process proceeds to step S51.

<< Step S51 >>
Next, in step S51, the target torque Trq and the target intake fresh air flow rate Qattrgt required by the driver are calculated from the accelerator pedal opening θacc based on the read input, and the target intake pipe pressure TP _dn is calculated based on the target torque Trq and the target intake fresh air flow rate Qattrgt. .. When the target intake pipe pressure TP _dn is obtained, the process proceeds to step S52.

<< Step S52 >>
Subsequently, in step S52, it is determined whether or not the actual intake pipe pressure Pm detected from the intake pipe pressure or the actual intake pipe pressure Pm estimated from the air amount Qa is equal to or higher than the atmospheric pressure Patm. If it is above the atmospheric pressure Patm, the process proceeds to step S53, and if it is below the atmospheric pressure Patm, the return is exited and the next start timing is waited for.

≪Step S53≫
In step S53, it is determined whether or not the actual intake pipe pressure Pm obtained in step S52 is equal to or higher than the operating pressure Pwg of the predetermined wastegate valve 33. If the working pressure is Pwg or less, the process proceeds to step S54, and if the working pressure is Pwg or more, the process proceeds to step S57.

<< Step S54 >>
In step S54, it is determined whether or not the difference (Pm-TP _dn ) between the actual intake pipe pressure Pm obtained in step S52 and the target intake pipe pressure TP _dn obtained in step S51 is equal to or greater than a predetermined value. If it is equal to or more than a predetermined value, the target air bypass valve opening degree θabtrgt (air bypass valve 34) is controlled to be opened. If it is equal to or less than a predetermined value, the target air bypass valve opening degree θabtrgt (air bypass valve 34) is controlled to be closed. After that, the process proceeds to step S55.

≪Step S55≫
In step S55, when the target intake pipe pressure TP _dn obtained in step S51 is realized by using the air bypass valve 44, the actual intake pipe pressure Pm obtained in step S52 is equal to or higher than the operating pressure Pwg of the predetermined wastegate valve 33. It is determined whether or not it is. If the working pressure is Pwg or more, the process proceeds to step S56, and if the working pressure is Pwg or less, the return is performed and the next start timing is waited.

<< Step S56 >>
In step S56, when it is determined that the actual intake pipe pressure Pm obtained in step S52 is equal to or higher than the operating pressure Pwg of the predetermined wastegate valve 33, the air bypass valve 34 is stopped so as to stop the control of the air bypass valve 34. close up. After that, the process proceeds to step S57.

≪Step S57≫
In step S57, in the high supercharging region after the low supercharging region, the difference (Pm-TP _dn ) between the actual intake pipe pressure Pm obtained in step S52 and the target intake pipe pressure TP _dn obtained in step S51 is predetermined. Determine if it is greater than or equal to the value. If it is equal to or more than a predetermined value, the target wastegate valve opening degree θwgtrgt (wastegate valve 33) is controlled to be opened. If it is equal to or less than a predetermined value, the target wastegate valve opening degree θwgtrgt (wastegate valve 33) is controlled to be closed. After that, it goes out to the return and waits for the next start timing.

As described above, also in the present embodiment, the same operation and effect as in the first embodiment can be obtained, and in addition, the wastegate valve 33 is controlled to open and close in the high supercharging pressure region after the low supercharging pressure region. By doing so, the rotation speed of the turbine can be optimized, and the destruction of the turbine caused by over-rotation can be prevented. That is, the durability and reliability of the turbocharger can be improved.

Whether or not the control method according to each of the above-described embodiments is implemented depends on, for example, the output signal (waveform) from the ECU (Engine Control Unit) of the automobile on which the internal combustion engine (engine) is mounted, the wastegate valve, and the air. It can be confirmed from the drive signal (waveform) of the bypass valve.

Further, the internal combustion engine used in each of the above-described embodiments has been described on the premise of a spark ignition type internal combustion engine provided with a spark plug, but the present invention is not limited to this, and the compression ignition type internal combustion engine ( For example, it can be applied to a diesel engine or a premixed compression ignition type internal combustion engine).

The present invention is not limited to the above-described embodiment, and includes various modifications. For example, the above-described embodiment has been described in detail in order to explain the present invention in an easy-to-understand manner, and is not necessarily limited to the one including all the described configurations. Further, it is possible to replace a part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. Further, it is possible to add / delete / replace a part of the configuration of each embodiment with another configuration.

10 ... Internal engine, 11 ... Exhaust passage, 12 ... Supercharger (compressor), 13 ... Precatalyst, 14 ... Main catalyst, 15 ... Particle removal filter, 16 ... EGR piping, 17 ... Gas cooler, 18 ... Combustion cylinder, 19 ... Intake passage, 20 ... Air cleaner, 21 ... EGR valve, 22 ... Differential pressure sensor, 23 ... Control device (ECU), 24 ... Air flow sensor, 25 ... Throttle valve, 26 ... Intake collector (intake piping), 27 ... Variable Phase valve timing mechanism, 28 ... Accelerator pedal sensor, 29 ... Rotation speed sensor, 30 ... Ignition plug, 31 ... Intercooler, 32 ... Pressure sensor, 33 ... Waste gate valve, 34 ... Air bypass valve, 35 ... Control unit (CPU) ), 40 ... Target torque calculation unit, 41 ... Target intake fresh air flow rate calculation unit, 42 ... Target EGR rate calculation unit, 43 ... Throttle passing EGR gas flow rate calculation unit, 44 ... Target throttle intake gas flow rate calculation unit, 45 ... Target Throttle valve opening degree calculation unit, 46 ... target EGR gas flow rate calculation unit, 47 ... target EGR valve opening degree calculation unit, 51 ... target waste gate valve opening degree calculation unit, 52 ... target air bypass valve opening degree calculation unit.

Claims (2)

(A) A step of reading an input value including at least the amount of depression of the accelerator pedal and the number of revolutions of the internal combustion engine, and
(B) A step of calculating the target torque and the target intake fresh air flow rate required by the driver based on the input value read in the step (a) above, and calculating the target intake pipe pressure based on the target torque and the target intake fresh air flow rate.
(C) A step of determining whether or not the actual intake pipe pressure estimated from the actual intake pipe pressure detected by the sensor or the amount of air taken in from the outside is equal to or higher than the atmospheric pressure.
(D) When it is determined in the step (c) that the actual intake pipe pressure is equal to or higher than the atmospheric pressure, the step of determining whether or not the actual intake pipe pressure is equal to or higher than the operating pressure of the predetermined wastegate valve.
(E) When it is determined in the step (d) that the actual intake pipe pressure is equal to or less than the operating pressure of the predetermined waste gate valve, the difference between the actual intake pipe pressure and the target intake pipe pressure is equal to or more than the predetermined value. Has a step to determine if there is, and
When it is determined in the step (e) that the difference between the actual intake pipe pressure and the target intake pipe pressure is equal to or more than a predetermined value, the air bypass valve is controlled to open and it is determined to be equal to or less than the predetermined value. , A control method for an internal combustion engine that controls the air bypass valve to close. The method for controlling an internal combustion engine according to claim 1.
(F) A step of controlling the air bypass valve based on the determination result of the step (e), and then determining whether or not the actual intake pipe pressure is equal to or higher than the operating pressure of the predetermined wastegate valve.
(G) In the step (f), when it is determined that the actual intake pipe pressure is equal to or higher than the operating pressure of the predetermined wastegate valve, the step of controlling the air bypass valve to be closed and the step of controlling the air bypass valve.
(H) After the step (g), there is a step of determining whether or not the difference between the actual intake pipe pressure and the target intake pipe pressure is equal to or larger than a predetermined value.
When it is determined in the step (h) that the difference between the actual intake pipe pressure and the target intake pipe pressure is equal to or more than a predetermined value, the wastegate valve is controlled to open and it is determined to be equal to or less than the predetermined value. , A method of controlling an internal combustion engine that controls the wastegate valve to close.

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