JP2018071497A - Internal combustion engine control device - Google Patents

Abstract

A control device for an internal combustion engine capable of accurately achieving a target value of supercharging pressure in a transient state. SOLUTION: Using a relationship established among compressor work, fresh air amount, pre-compressor temperature, pre-compressor pressure and post-compressor pressure, a target value of post-compressor pressure, fresh air amount, pre-compressor temperature, and pre-compressor value are used. The target value of compressor work is calculated from each current value of pressure. Next, the turbine work target value is calculated based on the compressor work target value and the turbo overall efficiency. In addition, the relationship between turbine work, pre-turbine temperature, pre-turbine pressure, turbine passing gas amount and turbine post-pressure is used to determine the target value of turbine work and the pre-turbine temperature, pre-turbine pressure and turbine passing gas amount. The target value of the turbine post-pressure is calculated from each current value. And the opening degree of a variable nozzle is determined based on the target value of turbine post-pressure. [Selection] Figure 2

Description

  The present invention relates to a control device for an internal combustion engine including a turbocharger having a variable nozzle or a wastegate valve.

  In an internal combustion engine including a turbocharger having a variable nozzle and a wastegate valve, the rotation of the turbine can be actively controlled by operating the variable nozzle and the wastegate valve. And by controlling the rotation of the turbine, it is possible to indirectly control the state quantity related to the rotation state of the turbine. For example, Japanese Unexamined Patent Application Publication No. 2014-47717 discloses that a target value of pressure in the exhaust manifold is set and the opening of the variable nozzle is determined so as to achieve the target value.

JP 2014-47717 A Japanese Patent No. 5963927

  By the way, the supercharging pressure is included in the state quantity related to the rotational state of the turbine. The supercharging pressure can also be controlled by operating a variable nozzle or a wastegate valve. However, it is not easy to accurately achieve the target value of the supercharging pressure in the transient state due to the response delay of the temperature and pressure of the intake / exhaust system.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a control device for an internal combustion engine that can accurately achieve a target value of supercharging pressure in a transient state.

  An internal combustion engine control apparatus according to the present invention is an internal combustion engine control apparatus including a turbocharger having a variable nozzle or a wastegate valve, and achieves a target value of supercharging pressure by the following logic. The operation amount of the variable nozzle or the wastegate valve is determined.

  The control device for an internal combustion engine according to the present invention obtains a target value for the supercharging pressure. Then, the target value of the post-compressor pressure that is the pressure in the intake passage on the outlet side of the compressor is calculated from the target value of the supercharging pressure. In addition, the current value of the fresh air amount, which is the flow rate of fresh air taken into the intake passage, is acquired, the current value of the pre-compressor temperature, which is the temperature in the intake passage on the inlet side of the compressor, is acquired. Acquires the current value of the pre-compressor pressure that is the pressure in the intake passage on the inlet side. The target value of the post-compressor pressure, the new air quantity, the pre-compressor value are calculated using the relationship between the compressor work, the new air quantity, the pre-compressor temperature, the pre-compressor pressure, and the post-compressor pressure. The target value of the compressor work is calculated from the current values of the temperature and the pre-compressor pressure.

  Next, the control apparatus for an internal combustion engine according to the present invention calculates a target value for turbine work, which is work to be performed by the turbine, based on the target value for compressor work and the overall efficiency of the turbocharger. Also, the current value of the pre-turbine temperature, which is the temperature in the exhaust passage on the inlet side of the turbine, is acquired, the current value of the pre-turbine pressure, which is the pressure in the exhaust passage on the inlet side of the turbine, is acquired, and further passes through the turbine. The current value of the amount of gas passing through the turbine that is the flow rate of the gas to be acquired is acquired. The turbine work target value and the turbine work are determined by using the relationship established between the turbine work, the temperature before the turbine, the pressure before the turbine, the amount of gas passing through the turbine, and the pressure in the exhaust passage on the outlet side of the turbine. A target value of the turbine post-pressure is calculated from the current values of the pre-temperature, the pre-turbine pressure, and the turbine passing gas amount.

  And the control apparatus of the internal combustion engine which concerns on this invention determines the operation amount of a variable nozzle or a wastegate valve based on the target value of turbine post-pressure.

  According to the control apparatus for an internal combustion engine according to the present invention, the operation amount of the variable nozzle or the wastegate valve is determined from the target value of the supercharging pressure according to the above-described logic, so that a response delay of the temperature and pressure of the intake / exhaust system occurs. Even in the transient state, the target value of the supercharging pressure can be achieved with high accuracy.

1 is a diagram illustrating a schematic configuration of an internal combustion engine according to a first embodiment of the present invention. It is a block diagram which shows the structure which calculates a target turbine post pressure from the target supercharging pressure with which the control apparatus of Embodiment 1 of this invention is provided. It is a block diagram which shows the structure which calculates each opening degree of a variable nozzle and an exhaust gas switching valve from the target turbine post pressure with which the control apparatus of Embodiment 1 of this invention is provided. It is a figure which shows the example of the opening degree characteristic map of a variable nozzle. It is a figure which shows the example of the opening degree characteristic map of an exhaust gas switching valve. It is a figure which shows schematic structure of the internal combustion engine of Embodiment 2 of this invention. It is a block diagram which shows the structure which calculates the opening degree of a variable nozzle from the target turbine post pressure with which the control apparatus of Embodiment 2 of this invention is provided.

Embodiment 1 FIG.
[Configuration of Internal Combustion Engine of Embodiment 1]
FIG. 1 is a diagram showing a schematic configuration of an internal combustion engine 2 according to Embodiment 1 of the present invention. The internal combustion engine 2 according to the present embodiment includes an engine body 10 configured as a diesel engine mounted on an automobile. An intake passage 12 is connected to the intake inlet of the engine body 10. An air cleaner 16 is provided near the inlet of the intake passage 12. An exhaust passage 14 is connected to the exhaust outlet of the engine body 10. A catalyst device 18 for purifying the exhaust gas is provided in the middle of the exhaust passage 14.

  The internal combustion engine 2 of the present embodiment is configured as a two-stage turbo system in which two turbochargers are arranged in series. Specifically, the internal combustion engine 2 includes a low-pressure turbocharger (hereinafter referred to as “LP turbocharger”) 20 and a high-pressure turbocharger (hereinafter referred to as “LP turbocharger”) having a capacity smaller than that of the LP turbocharger 20. 22) (referred to as “HP turbocharger”). The LP turbocharger 20 includes a turbine (hereinafter referred to as “LP turbine”) 20a that is rotated by exhaust energy, and a compressor (hereinafter referred to as “LP compressor”) 20b that is driven by the LP turbine 20a. ing. Similarly, the HP turbocharger 22 includes a turbine (hereinafter referred to as “HP turbine”) 22a and a compressor (hereinafter referred to as “HP compressor”) 22b. The HP turbine 22 a includes a variable nozzle (hereinafter referred to as “VN”) 23.

  The LP turbine 20a and the LP compressor 20b are respectively arranged in the exhaust passage 14 and the intake passage 12. The HP turbine 22a is disposed upstream of the LP turbine 20a in the exhaust passage 14, and the HP compressor 22b is disposed downstream of the LP compressor 20b in the exhaust passage 14. An intercooler 24 and an intake throttle valve 26 are arranged in this order further downstream of the HP compressor 22b in the intake passage 12.

  In the intake passage 12 extending from the LP compressor 20b to the intercooler 24, an intake bypass passage 28 that bypasses the HP compressor 22b is provided. An intake control valve (hereinafter referred to as “ACV”) 30 for controlling the flow rate of air flowing through the intake bypass passage 28 is disposed in the middle of the intake bypass passage 28.

  The exhaust passage 14 is provided with an exhaust bypass passage 32 that bypasses the LP turbine 20a and an exhaust bypass passage 34 that bypasses the HP turbine 22a. An exhaust bypass valve (hereinafter referred to as “EBV”) 36 as a waste gate valve of the LP turbine 20 a is disposed in the middle of the exhaust bypass passage 32. An exhaust gas switching valve (hereinafter referred to as “ECV”) 38 as a waste gate valve of the HP turbine 22 a is disposed in the exhaust bypass passage 34.

  Further, an EGR passage 40 that connects the upstream of the HP turbine 22 a in the exhaust passage 14 and the downstream of the intake throttle valve 26 in the intake passage 12 is provided. In the EGR passage 40, an EGR cooler 42 and an EGR valve 44 are arranged in this order from the upstream side to the downstream side. The EGR passage 40 is provided with a bypass passage 46 that bypasses the EGR cooler 42. A bypass valve 48 that switches the flow path of the EGR gas between the bypass passage 46 and the EGR cooler 42 is provided at the junction where the bypass passage 46 joins the EGR passage 40.

  As shown in FIG. 1, the internal combustion engine 2 of the present embodiment includes an ECU (Electronic Control Unit) 50 as a control device. Various information and signals regarding the operating state and operating conditions of the internal combustion engine 2 are input to the ECU 50 from various sensors. For example, information relating to the fresh air amount Gadly, which is the flow rate of fresh air sucked into the intake passage 12, is input from an air flow sensor (not shown) disposed in the vicinity of the air cleaner 16. In addition, from a pressure sensor (not shown) disposed between the LP compressor 20b and the HP compressor 22b in the intake passage 12, information related to the pre-compressor pressure PC, which is the pressure in the intake passage on the inlet side of the HP compressor 22b, is input. Information related to the pre-compressor temperature TC, which is the temperature in the intake passage on the inlet side of the HP compressor 22b, is input from a temperature sensor (not shown) arranged at the same position. Further, from a pressure sensor (not shown) arranged upstream of the HP turbine 22a in the exhaust passage 14, information related to the turbine pre-pressure P4 that is the pressure in the exhaust passage on the inlet side of the HP turbine 22a is inputted and arranged at the same position. From the temperature sensor (not shown), information related to the pre-turbine temperature T4, which is the temperature in the exhaust passage on the inlet side of the HP turbine 22a, is input. The ECU 50 operates various actuators such as the above-described VN 23 and ECV 38 based on these information and signals.

[Supercharging pressure control of Embodiment 1]
One of the functions of the ECU 50 is a function of controlling the operation of the HP turbocharger 22 so that the supercharging pressure becomes a target value (hereinafter referred to as “target supercharging pressure”). The supercharging pressure means any one of the intake manifold internal pressure Pim, the intake passage internal pressure Pia on the inlet side of the intake throttle valve 26, and the after-compressor pressure P3 which is the intake passage internal pressure on the outlet side of the compressor. Here, the intake passage pressure Pia is defined as the supercharging pressure. The operation amounts for controlling the operation of the HP turbocharger 22 are the respective opening amounts of the VN 23 and the ECV 38. However, the ECU 50 does not directly calculate the opening degrees of the VN 23 and the ECV 38 from the target supercharging pressure, but first, the turbine post-pressure that is the exhaust passage internal pressure on the outlet side of the HP turbine 22a based on the target supercharging pressure. Target value (hereinafter referred to as “target turbine post-pressure”) is calculated. And each opening degree of VN23 and ECV38 is determined based on target turbine post-pressure.

  FIG. 2 is a block diagram showing a configuration for calculating the target turbine post-pressure from the target boost pressure included in the ECU 50. The ECU 50 includes arithmetic units 101, 102, 103, and 104. Hereinafter, functions of the arithmetic units 101, 102, 103, and 104 will be described.

The calculation unit 101 calculates a target value of the post-compressor pressure (hereinafter referred to as “target post-compressor pressure”) P3trg from the target supercharging pressure Piatrg according to the following formula 1. ΔP in Equation 1 is a pressure loss generated in the intercooler 24, and an estimated value corresponding to the flow rate of the gas passing through the intercooler 24 is used.

The computing unit 102 calculates a target value of compressor work (hereinafter referred to as “target compressor work”) WCtrg, which is work performed by the HP compressor 22b, according to the following Expression 2. Expression 2 is an expression representing a relationship that holds among the compressor work, the fresh air amount, the pre-compressor temperature, the pre-compressor pressure, and the post-compressor pressure. The target compressor work WCtrg is obtained by inputting the current values of the target post-compressor pressure P3trg, the fresh air amount Gadly, the pre-compressor temperature TC, and the pre-compressor pressure PC into Equation 2. In Equation 2, Cpa is a constant temperature specific heat, and κ is a specific heat ratio.

The calculation unit 103 calculates a target value (hereinafter referred to as “target turbine work”) WTtrg of the turbine work, which is a work to be performed by the HP turbine 22a, from the target compressor work WCtrg according to the following Expression 3. Note that ηtot in Equation 3 is the overall efficiency of the turbocharger. The overall efficiency of the turbocharger may be a fixed value, or may be a variable defined by a map with the rotation speed of the HP turbine 22a as an axis, for example.

The calculation unit 104 calculates the target turbine post-pressure P4Mtrg according to the following Equation 4. Expression 4 is an expression representing a relationship that holds among turbine work, pre-turbine temperature, pre-turbine pressure, turbine passing gas amount, and post-turbine pressure. By inputting the current values of the target turbine work WTtrg, the pre-turbine temperature T4, the pre-turbine pressure P4, and the turbine passing gas amount G4 into Equation 4, the target post-turbine pressure P4Mtrg is obtained. The turbine passing gas amount G4 is a flow rate obtained by adding the fuel injection amount to the fresh air amount. Cpg is a constant temperature specific heat, and κ is a specific heat ratio.

  FIG. 3 is a block diagram showing a configuration for calculating each opening degree of VN 23 and ECV 38 from the target turbine post-pressure provided in ECU 50. The ECU 50 includes calculation units 105 and 106. Hereinafter, each function of the arithmetic units 105 and 106 will be described.

The calculation unit 105 assumes that the structure (the portion surrounded by the alternate long and short dash line in FIG. 1) composed of the HP turbines 22a, VN23, and ECV38 is one nozzle, and calculates the effective opening area μA of the nozzle according to the following Expression 5. . The Φ function in Equation 5 is calculated by Equation 6. In Equations 5 and 6, Pus is the pressure on the inlet side of the nozzle, Tus is the temperature on the inlet side of the nozzle, Pds is the pressure on the outlet side of the nozzle, and m is the flow rate of the gas passing through the nozzle. The target post-turbine pressure P4Mtrg is input to Pds, the current value of the pre-turbine pressure P4 is input to Pus, the current value of the pre-turbine temperature T4 is input to Tus, and the current value of the turbine passing gas amount G4 is input to m Thus, the effective opening area μA of the nozzle is obtained.

  With respect to one value of the effective opening area μA, the opening degree of the VN 23 (hereinafter referred to as “VN opening degree”) and the opening degree of the ECV 38 (hereinafter referred to as “ECV opening degree”) to achieve it. There are many combinations. Therefore, the calculation unit 106 uniquely determines the VN opening and the ECV opening from the effective opening area μA by using the opening characteristic maps shown in FIGS. 4 and 5. The VN opening characteristic map shown in FIG. 4 is a map in which the VN opening is associated with the effective opening area μA. The ECV opening characteristic map shown in FIG. 5 is a map in which the ECV opening is associated with the effective opening area μA. Each map is prepared for each nozzle passing gas amount (that is, turbine passing gas amount). When attention is paid to a certain flow rate, when the effective opening area μA is equal to or smaller than a predetermined value, the ECV opening is fully closed, and the VN opening is changed according to the effective opening area μA. This means that the supercharging pressure is controlled by operating the VN 23. When the effective opening area μA is equal to or greater than a predetermined value, the VN opening is a constant value corresponding to full opening, and the ECV opening is changed according to the effective opening area μA. This means that the supercharging pressure is controlled by the operation of the ECV opening.

  According to the configuration of the ECU 50 described above, the temperature and pressure of the intake and exhaust systems are taken into account in the process of calculating the VN opening and the ECV opening from the target boost pressure. Therefore, it is possible to calculate the VN opening and the ECV opening that can accurately achieve the target supercharging pressure even in a transient state in which a response delay of the temperature and pressure of the intake and exhaust systems occurs.

Embodiment 2. FIG.
[Configuration of Internal Combustion Engine of Embodiment 2]
FIG. 6 is a diagram showing a schematic configuration of the internal combustion engine 52 according to the second embodiment of the present invention. The internal combustion engine 52 according to the present embodiment is a single turbo system provided with a single turbocharger. An intake passage 62 is connected to an intake inlet of an engine body 60 configured as a diesel engine. The intake passage 62 is provided with an air cleaner 66, a turbocharger compressor 68 b, an intercooler 72, and an intake throttle valve 74 from the upstream side to the downstream side. An exhaust passage 64 is connected to the exhaust outlet of the engine body 60. The exhaust passage 64 is provided with a turbocharger turbine 68a. The turbine 68 a includes a variable nozzle (hereinafter referred to as “VN”) 70. Further, an EGR passage 76 that connects the upstream of the turbine 68 a in the exhaust passage 64 and the downstream of the intake throttle valve 74 in the intake passage 62 is provided. In the EGR passage 76, an EGR cooler 80 and an EGR valve 78 are arranged in this order from the upstream side to the downstream side. The EGR passage 76 is provided with a bypass passage 82 that bypasses the EGR cooler 80. A bypass valve 84 that switches the flow path of the EGR gas between the bypass passage 82 and the EGR cooler 80 is provided at the junction where the bypass passage 82 joins the EGR passage 76.

  As shown in FIG. 6, the internal combustion engine 52 of the present embodiment includes an ECU (Electronic Control Unit) 90 as a control device. Various information and signals related to the operating state and operating conditions of the internal combustion engine 52 are input to the ECU 90 from various sensors. For example, information about the fresh air amount Gadly, which is the flow rate of fresh air sucked into the intake passage 62, is input from an air flow sensor (not shown) disposed in the vicinity of the air cleaner 66. In addition, from a pressure sensor (not shown) arranged upstream of the compressor 68b in the intake passage 12, information related to the pre-compressor pressure PC, which is the pressure in the intake passage on the inlet side of the compressor 68b, is inputted and shown in the drawing arranged at the same position. Information regarding the pre-compressor temperature TC, which is the temperature in the intake passage on the inlet side of the compressor 68b, is input from the temperature sensor that does not. Further, from a pressure sensor (not shown) arranged upstream of the turbine 68a in the exhaust passage 14, information on the turbine pre-pressure P4 that is the pressure in the exhaust passage on the inlet side of the turbine 68a is inputted and shown in the figure arranged at the same position. From the temperature sensor that does not, information related to the pre-turbine temperature T4, which is the temperature in the exhaust passage on the inlet side of the turbine 68a, is input. The ECU 90 operates various actuators such as the VN 70 based on these information and signals.

[Supercharging pressure control of Embodiment 2]
The ECU 90 has a function of operating the VN 70 so that the supercharging pressure becomes the target value (hereinafter referred to as “target supercharging pressure”). Specifically, the ECU 90 calculates a target value of the turbine post-pressure (hereinafter referred to as “target turbine post-pressure”) that is the pressure in the exhaust passage on the outlet side of the turbine 68a based on the target supercharging pressure. Then, the opening degree of VN 70 (hereinafter referred to as “VN opening degree”) is determined based on the target turbine post-pressure. The ECU 90 has the same configuration as the calculation units 101, 102, 103, and 104 shown in FIG. 2 in order to calculate the target turbine post-pressure from the target boost pressure.

  FIG. 7 is a block diagram showing a configuration for calculating the VN opening degree from the target turbine post-pressure provided in the ECU 90. The ECU 50 includes calculation units 105 and 107. The function of the arithmetic unit 105 is as described in the first embodiment. The calculation unit 105 assumes that the turbine 68 provided with the VN 70 is one nozzle, and sets the target post-turbine pressure P4Mtrg, the current value of the pre-turbine pressure P4, the pre-turbine temperature T4, and the turbine passing gas amount G4 to Equation 5. This is input to calculate the effective opening area μA of the nozzle. The calculation unit 107 uniquely determines the VN opening from the effective opening area μA by using a VN opening characteristic map (not shown). The VN opening characteristic map is prepared for each nozzle passing gas amount (that is, turbine passing gas amount).

Other embodiments.
Each current value of the fresh air amount Gadly, the pre-compressor temperature TC, and the pre-compressor pressure TP used for calculating the target compressor work may be a measured value measured by a sensor or an estimated value estimated from a related physical quantity. Similarly, the current values of the pre-turbine temperature T4, the pre-turbine pressure P4, and the turbine passing gas amount G4 used for calculating the target post-turbine pressure may be measured values measured by sensors or estimated from related physical quantities. It may be an estimated value.

  In the internal combustion engine 2 of the first embodiment shown in FIG. 1, only one of the VN 23 and the ECV 38 may be used. In the internal combustion engine 52 of the second embodiment shown in FIG. 6, a waste gate valve may be used instead of the VN 70.

2,52 Internal combustion engine 12,62 Intake passage 14,64 Exhaust passage 22a, 68a Turbine 22b, 68b Compressor 23,70 Variable nozzle 50,90 ECU

Claims (1)

In a control device for an internal combustion engine equipped with a turbocharger having a variable nozzle or a wastegate valve,
Means for obtaining a target value of the supercharging pressure;
Means for calculating a target value of the post-compressor pressure that is the pressure in the intake passage on the outlet side of the compressor from the target value of the supercharging pressure;
Means for acquiring a current value of a fresh air amount that is a flow rate of fresh air taken into the intake passage;
Means for obtaining a current value of the pre-compressor temperature, which is the temperature in the intake passage on the inlet side of the compressor;
Means for obtaining a current value of the pre-compressor pressure, which is the pressure in the intake passage on the inlet side of the compressor;
The target value of the post-compressor pressure and the new value are calculated using a relationship that is established among the compressor work, the new air amount, the pre-compressor temperature, the pre-compressor pressure, and the post-compressor pressure. Means for calculating a target value of the compressor work from current values of air volume, temperature before the compressor, and pressure before the compressor;
Means for calculating a turbine work target value, which is a work to be performed by the turbine based on the compressor work target value and the overall efficiency of the turbocharger;
Means for obtaining a current value of the temperature before the turbine, which is the temperature in the exhaust passage on the inlet side of the turbine;
Means for obtaining a current value of the pre-turbine pressure, which is the pressure in the exhaust passage on the inlet side of the turbine;
Means for obtaining a current value of the amount of gas passing through the turbine, which is a flow rate of gas passing through the turbine;
The target of the turbine work is determined by using a relationship that is established among the turbine work, the temperature before the turbine, the pressure before the turbine, the amount of gas passing through the turbine, and the pressure in the exhaust passage on the outlet side of the turbine. Means for calculating a target value of the post-turbine pressure from a value and each current value of the pre-turbine temperature, the pre-turbine pressure, and the turbine passing gas amount;
Means for determining an operation amount of the variable nozzle or the wastegate valve based on a target value of the turbine post-pressure;
A control device for an internal combustion engine, comprising:

Images