JP6453122B2 - Control device for variable capacity turbocharger - Google Patents

Description

  The present invention relates to a control device for a variable displacement turbocharger.

  2. Description of the Related Art Conventionally, diesel engines are equipped with an exhaust gas recirculation (EGR) device that introduces a portion of exhaust gas into an intake passage in order to reduce NOx contained in the exhaust gas (for example, a patent) Reference 1). The EGR device includes an EGR valve in an EGR passage connecting the exhaust passage and the intake passage, and adjusts the amount of EGR gas introduced into the intake passage by controlling the opening of the EGR valve. The EGR control device that controls the opening degree of the EGR valve is, for example, feedback control based on a deviation between a target air amount of intake air based on an engine speed and a fuel injection amount and an actual intake air amount that is an actually measured value of the intake air. To adjust the amount of EGR gas introduced and control the intake air amount of the engine. As a result, the working gas in which the intake air and the EGR gas are mixed is supplied to the engine.

  Further, when the EGR is executed, the pressure on the exhaust side is required to be higher than the pressure on the intake side. Therefore, in Patent Document 1, the opening degree of the variable nozzle of the variable displacement turbocharger is controlled so that the pressure on the exhaust side is higher than the pressure on the intake side.

JP 2002-332879 A

  By the way, in a diesel engine, the amount of NOx emission decreases as the EGR gas in the working gas increases. On the other hand, the amount of particulate matter (PM) emission decreases as the intake air in the working gas increases. In this way, NOx and particulate matter are in a trade-off relationship that when one is reduced, the other is increased. Therefore, a technique capable of reducing both NOx and particulate matter is desired.

  It is an object of the present invention to provide a control device for a variable capacity turbocharger that can reduce NOx and particulate matter.

  A control apparatus for a variable capacity turbocharger that solves the above problem is to recirculate part of the exhaust gas flowing into the turbine to the intake passage and to open the EGR valve so that the intake air amount of the engine becomes the target air amount. A variable displacement turbocharger control device applied to an engine system equipped with an EGR device for controlling the engine, a basic target pressure calculation unit for calculating a basic target pressure of exhaust gas flowing into the turbine, and the engine A working gas amount calculating unit for calculating a working gas amount to be sucked in; a target working gas amount calculating unit for calculating a target working gas amount that is a target amount of the working gas amount; the target working gas amount and the working gas amount; A correction value calculation unit that calculates a correction value of the basic target pressure according to a deviation of the target pressure, and a target pressure that sets a value obtained by correcting the basic target pressure with the correction value as a target pressure And a control unit that controls the opening of the variable nozzle so that the pressure of the exhaust gas flowing into the turbine becomes the target pressure, and the correction value calculation unit has the target working gas amount of the operation The correction value for increasing the basic target pressure when the amount is larger than the gas amount is calculated.

  According to the above configuration, when the target working gas amount is larger than the working gas amount, the target pressure is set to a value higher than the basic target pressure. Therefore, since the pressure of the exhaust gas flowing into the turbine increases, the pressure of the intake air after supercharging is increased by increasing the pressure of the EGR gas and increasing the work of the turbocharger. As a result, the amount of working gas that can be sucked into the engine increases by increasing the pressure of the working gas. The intake air amount is controlled to the target air amount by the EGR device. As a result, it is possible to increase the EGR rate while ensuring the amount of air necessary for combustion, and therefore it is possible to reduce NOx and particulate matter.

In the variable capacity turbocharger control device, the target working gas amount calculation unit can calculate the target working gas amount using the target air amount and a target EGR rate that is a target value of an EGR rate. It is.
The variable capacity turbocharger control device includes a target EGR rate selection unit that selects the target EGR rate from target EGR rate data that defines the target EGR rate for each engine speed and fuel injection amount; and the engine speed And a target air amount selection unit that selects the target air amount from target air amount data that defines the target air amount for each fuel injection amount.

  According to the above configuration, the target working gas amount is calculated using the target EGR rate selected from the target EGR rate data and the target air amount selected from the target air amount data. Thereby, the calculation of the target EGR rate and the target air amount is simplified, and as a result, the calculation of the target working gas amount can be simplified.

  The variable displacement turbocharger control device includes: a basic expansion ratio selection unit that selects the basic expansion ratio from basic expansion ratio data that defines a basic expansion ratio for each engine speed and fuel injection amount; and It is preferable that the basic target pressure calculation unit calculates the basic target pressure by multiplying the basic expansion ratio by the outlet pressure.

  According to the above configuration, the basic target pressure is calculated by multiplying the basic expansion ratio selected from the basic expansion ratio data by the outlet pressure calculated by the outlet pressure calculation unit. Thereby, the calculation of the basic target pressure can be simplified.

The schematic block diagram which shows schematic structure of the engine system by which one Embodiment of the control apparatus of a variable capacity type turbocharger is mounted. The block diagram which shows an example of a structure of the control apparatus of a variable capacity type turbocharger. The calculation block diagram which shows a part of calculation which a calculating part performs. The graph which shows an example of basic expansion ratio data typically. The graph which shows typically an example of target EGR rate data. The graph which shows typically an example of target air quantity data. FIG. 5 is a graph showing an example of a change in the ratio of the EGR gas amount and the intake air amount in the working gas, in which the embodiment shows the case where the pressure obtained by correcting the basic target pressure with the correction value is set as the target pressure, and the comparative example is the basic The case where the target pressure is set to the target pressure is shown.

  With reference to FIGS. 1 to 7, an embodiment embodying a variable displacement turbocharger control device will be described. First, the overall configuration of an engine system in which a variable capacity turbocharger is mounted will be described with reference to FIG.

  As shown in FIG. 1, the engine system includes a diesel engine 10 (hereinafter referred to as an engine 10). The cylinder block 11 of the engine 10 is formed with four cylinders 12 arranged in a row. Fuel is injected into each cylinder 12 from an injector 13. Connected to the cylinder block 11 are an intake manifold 14 for supplying intake air to each cylinder 12 and an exhaust manifold 15 into which exhaust gas from each cylinder 12 flows.

  In the intake passage 16 connected to the intake manifold 14, an air cleaner (not shown), a compressor 18 constituting a turbocharger 17, and an intercooler 19 are provided in order from the upstream side. The exhaust passage 20 connected to the exhaust manifold 15 is provided with a turbine 22 that is connected to the compressor 18 via a connecting shaft 21 and constitutes the turbocharger 17.

  The engine system includes an EGR device 23. The EGR device 23 includes an EGR passage 25 that connects the exhaust manifold 15 and the intake passage 16. An EGR cooler 26 is provided in the EGR passage 25, and an EGR valve 27 capable of changing the flow path cross-sectional area of the EGR passage 25 is provided on the intake passage 16 side of the EGR cooler 26. The opening degree of the EGR valve 27 is controlled by the EGR control device 24. When the EGR valve 27 is in an open state, a part of the exhaust gas flowing into the turbine 22 through the EGR passage 25 is introduced into the intake passage 16 as EGR gas, and the cylinder 12 is mixed with the exhaust gas and the intake air. A working gas that is a gas is supplied.

  The turbocharger 17 is a variable capacity turbocharger (VNT: Variable Nozzle Turbo) in which a variable nozzle 28 is disposed in the turbine 22. The opening of the variable nozzle 28 is changed by driving an actuator 29 having a stepping motor, so that the exhaust pressure Pem, which is the pressure of the exhaust gas in the exhaust manifold 15 and the pressure of the exhaust gas flowing into the turbine 22. And the inflow amount Gti of the exhaust gas to the turbine 22 is adjusted. The opening degree of the variable nozzle 28 is controlled by a VNT control device 50 that is a control device for a variable displacement turbocharger.

  The engine system includes various sensors. The intake air amount sensor 31 is located upstream of the compressor 18 in the intake passage 16 and detects an intake air amount Ga that is a mass flow rate of intake air flowing into the compressor 18. The EGR pressure sensor 33 and the EGR temperature sensor 34 are located between the EGR cooler 26 and the EGR valve 27 in the EGR passage 25. The EGR pressure sensor 33 detects the EGR pressure Pr that is the pressure of the EGR gas flowing into the EGR valve 27, and the EGR temperature sensor 34 detects the EGR temperature Tr that is the temperature of the EGR gas flowing into the EGR valve 27. The boost pressure sensor 36 is located between the connection portion of the EGR passage 25 with respect to the intake passage 16 and the intake manifold 14 and detects the boost pressure Pb that is the pressure of the working gas. The working gas temperature sensor 37 is attached to the intake manifold 14 and detects the working gas temperature Twg, which is the temperature of the working gas flowing into the cylinder 12. The engine speed sensor 38 detects an engine speed Ne that is the speed of the crankshaft 30. The variable nozzle opening sensor 40 detects the nozzle opening VTa that is the opening of the variable nozzle 28 based on the drive amount of the actuator 29. Each of the sensors outputs a signal indicating the detected detection value to the VNT control device 50.

  The EGR control device 24 sets the target air amount tGa of the intake air based on the engine speed Ne detected by the engine speed sensor 38 and the fuel injection amount Gf output from the fuel injection control unit 42. The EGR control device 24 sets the target air amount tGa using the same data as the target air amount data 76 described later. The target air amount tGa is an air amount that suppresses the generation of particulate matter (hereinafter referred to as PM) when the engine 10 is driven under the engine speed Ne and the fuel injection amount Gf. The EGR control device 24 opens the EGR valve 27 so that the intake air amount Ga becomes the target air amount tGa by feedback control based on the deviation between the target air amount tGa and the intake air amount Ga detected by the intake air amount sensor 31. Control the degree.

  As shown in FIG. 2, the VNT control device 50 (hereinafter simply referred to as the control device 50) includes a control unit 51 including a CPU, a ROM, a RAM, and the like. The control unit 51 includes an acquisition unit 52 that acquires an external signal, a calculation unit 53 that performs various calculations, and a storage unit 54 that stores various data such as various control programs and basic expansion ratio data 71. In addition, the control device 50 includes a nozzle driving unit 55 that drives the actuator 29. The control unit 51 calculates the target pressure tPem of the exhaust pressure Pem using the signal acquired by the acquisition unit 52 and the various data stored in the storage unit 54 according to various control programs stored in the storage unit 54. The opening degree of the variable nozzle 28 is controlled so that the target pressure tPem is realized. The control device 50 receives a signal indicating the atmospheric pressure Patm from the atmospheric pressure sensor 41 and a signal indicating the fuel injection amount Gf from the fuel injection control unit 42 that controls fuel injection.

  Based on the signals output from the various sensors described above, the acquisition unit 52 receives the intake air amount Ga, EGR pressure Pr, EGR temperature Tr, boost pressure Pb, working gas temperature Twg, engine speed Ne, nozzle opening VTa, and The atmospheric pressure Patm is acquired. The acquisition unit 52 acquires the fuel injection amount Gf based on the signal from the fuel injection control unit 42.

  The calculation unit 53 includes an inflow temperature Tti that is the temperature of the exhaust gas flowing into the turbine 22, an inflow amount Gti that is a mass flow rate of the exhaust gas that flows into the turbine 22, and an outlet pressure Pte that is the pressure of the exhaust gas at the outlet of the turbine 22. Are provided, and a first calculator 53a for calculating the target pressure tPem of the exhaust pressure Pem. The calculation unit 53 includes a third calculation unit 53c that calculates the target opening area tA of the variable nozzle 28 using the inflow temperature Tti, the inflow amount Gti, the outlet pressure Pte, and the target pressure tPem. This target pressure tPem is a very important parameter for driving the turbocharger 17. The target pressure tPem has different optimum values depending on the purpose, for example, reduction of NOx and PM, suppression of excessive rotation and surging of the turbocharger 17, formation of a minimum differential pressure in the EGR valve 27 when performing EGR, etc. It is.

  The third computing unit 53c computes the target opening area tA by substituting each value into Equation (1) based on Bernoulli's theorem. The third computing unit 53c substitutes the inflow temperature Tti for “T1”, the inflow amount Gti for “G”, the outlet pressure Pte for “P2”, and the target pressure tPem for “P1”, thereby obtaining the computation result “ A target opening area tA is calculated as “A”. In Equation (1), κ is the specific heat ratio of the exhaust gas, and R is a gas constant.

  The calculation unit 53 calculates a target nozzle opening tVT that embodies the target opening area tA obtained from the equation (1), and changes the opening of the variable nozzle 28 from the nozzle opening VTa to the target nozzle opening tVT. An instruction opening VTc which is an opening required for the operation is calculated. The calculating unit 53 outputs the indicated opening degree VTc to the nozzle driving unit 55.

  The nozzle drive unit 55 generates a drive signal for changing the opening of the variable nozzle 28 by the indicated opening VTc input from the calculation unit 53, and outputs the generated drive signal to the actuator 29.

  As shown in FIG. 3, the first calculation unit 53 a includes various calculation units. The working gas amount calculation unit 56 calculates a working gas amount Gwg that is a mass flow rate of the working gas supplied to the cylinder 12. The working gas amount calculation unit 56 performs a predetermined calculation based on the state equation P × V = Gwg × R × T as a boost pressure Pb, an engine speed Ne, an engine D displacement D, a working gas temperature Twg, and a gas constant R. The working gas amount Gwg is calculated by performing the operation.

The EGR amount calculation unit 57 calculates an EGR amount Gr that is a mass flow rate of the EGR gas by subtracting the intake air amount Ga from the working gas amount Gwg.
The EGR rate calculation unit 58 calculates the EGR rate η (= Gr / Gwg) by dividing the EGR amount Gr by the working gas amount Gwg.

  The inflow temperature calculation unit 59 is based on the inflow temperature based on the working gas amount Gwg, the EGR rate η, the fuel injection amount Gf that is an input value from the fuel injection control unit 42, and the inflow temperature data 60 stored in the storage unit 54. Tti is calculated. The inflow temperature data 60 is data in which the temperature of the exhaust gas is uniquely defined based on experiments conducted in advance and using the working gas amount Gwg, the EGR rate η, and the fuel injection amount Gf as parameters. Then, the inflow temperature calculation unit 59 selects from the inflow temperature data 60 an inflow temperature Tti corresponding to the working gas amount Gwg, the EGR rate η, and the fuel injection amount Gf.

  The inflow amount calculation unit 61 calculates an inflow amount Gti that is a mass flow rate of the exhaust gas flowing into the turbine 22. The inflow amount calculation unit 61 calculates the inflow amount Gti by adding the fuel injection amount Gf to the intake air amount Ga.

  The EGR pressure loss calculation unit 62 calculates an EGR gas pressure loss ΔPr in the EGR passage 25 based on the EGR amount Gr and the EGR passage data 63 stored in the storage unit 54. The EGR passage data 63 is data in which the pressure loss ΔPr of EGR gas between the inlet of the EGR passage 25 and the EGR pressure sensor 33 is defined for each EGR amount Gr based on experiments performed in advance. The EGR pressure loss calculation unit 62 selects the pressure loss ΔPr corresponding to the EGR amount Gr from the EGR passage data 63.

The exhaust pressure calculation unit 64 calculates an exhaust pressure Pem (= Pr + ΔPr) that is a pressure in the exhaust manifold 15 by adding a pressure loss ΔPr to the EGR pressure Pr.
The outlet pressure calculation unit 65 calculates the outlet pressure Pte based on the inflow temperature Tti, the inflow amount Gti, the atmospheric pressure Patm, and the exhaust passage data 66 stored in the storage unit 54. The exhaust passage data 66 is based on Gti × (Tti ^) where the pressure loss ΔPep generated in the exhaust gas from the outlet of the turbine 22 to the atmosphere is discharged based on the inflow amount Gti into the turbine 22 based on experiments and the like conducted in advance. 1/2) / Pem. The outlet pressure calculator 65 selects a pressure loss ΔPep corresponding to the inflow amount Gti from the exhaust passage data 66, and calculates the outlet pressure Pte by adding the selected pressure loss ΔPep to the atmospheric pressure Patm. Thus, the number of sensors exposed to the high-temperature exhaust gas can be reduced by obtaining the outlet pressure Pte by calculation.

  The second calculation unit 53b includes various calculation units. The basic expansion ratio selection unit 70 selects a basic expansion ratio πS that is an expansion ratio suitable for the operating state of the engine 10 from the basic expansion ratio data 71 stored in the storage unit 54.

  As shown in FIG. 4, the basic expansion ratio data 71 is data in which the basic expansion ratio πS is uniquely defined based on experiments performed in advance and using the engine speed Ne and the fuel injection amount Gf as parameters. . Each of the basic expansion ratios πS has a specific engine speed Ne at which the fuel injection amount Gf is maximized in the middle speed range of the engine 10. Further, each of the basic expansion ratios πS is such that, in a region where the engine speed Ne is lower than the specific engine speed Ne, the corresponding fuel injection amount Gf decreases as the engine speed Ne decreases, and the specific engine speed Ne In a region higher than Ne, the corresponding fuel injection amount Gf decreases as the engine speed Ne increases. As a result, surging of the turbocharger 17 is suppressed in the low rotation range of the engine 10, and excessive rotation of the turbocharger 17 is suppressed in the high rotation range of the engine 10.

The basic target pressure calculation unit 72 calculates the basic target pressure PemS by multiplying the outlet pressure Pte by the basic expansion ratio πS.
The target EGR rate selection unit 73 selects a target EGR rate tη that is a target value of the EGR rate according to the engine speed Ne and the fuel injection amount Gf from the target EGR rate data 74 stored in the storage unit 54.

  As shown in FIG. 5, the target EGR rate data 74 is data defining the target EGR rate tη for each engine speed Ne and fuel injection amount Gf. The engine speed Ne is a parameter indicating the amount of working gas that can be drawn into the engine 10. The fuel injection amount Gf is a parameter indicating the amount of air required for the engine 10. This target EGR rate tη is an EGR rate defined based on the results of experiments and simulations performed in advance, and the target air amount when the engine 10 is driven under the engine speed Ne and the fuel injection amount Gf. This is an EGR rate at which generation of NOx is suppressed when tGa air is supplied to the engine 10.

  In the target EGR rate data 74, each of the fuel injection amounts Gf has a maximum value of the target EGR rate tη in the middle rotation range of the engine 10. The middle rotation region is a region defined according to the setting of the engine 10, for example, and is a rotation region that is used more frequently than other rotation regions. Further, for each of the fuel injection amounts Gf, the lower the target EGR rate tη is defined as the difference from the engine speed Ne corresponding to the maximum value is larger. That is, the target EGR rate data 74 defines a target EGR rate tη that increases the EGR rate in the middle rotation range where the frequency of use is high.

  Further, in the target EGR rate data 74, a target EGR rate tη that is lower as the fuel injection amount Gf is larger is defined for each engine speed Ne. That is, the target EGR rate data 74 defines a target EGR rate tη that increases the amount of air supplied to the engine 10 as the fuel injection amount Gf increases as long as the engine speed Ne is the same.

The target air amount selection unit 75 selects a target air amount tGa corresponding to the engine speed Ne and the fuel injection amount Gf from the target air amount data 76 stored in the storage unit 54.
As shown in FIG. 6, the target air amount data 76 is data defining the target air amount tGa for each engine speed Ne and fuel injection amount Gf. The target air amount tGa is defined based on the results of experiments and simulations performed on the engine 10 in advance, and generation of PM is suppressed when the engine 10 is driven under the engine speed Ne and the fuel injection amount Gf. The amount of air. The target air amount tGa increases as the engine speed Ne increases if the fuel injection amount Gf is the same, and increases as the fuel injection amount Gf increases if the engine speed Ne is the same.

  The EGR control device 24 obtains the target air amount tGa using the same data as the target air amount data 76. That is, the target air amount tGa by the target air amount selector 75 and the target air amount by the EGR control device 24 are the same value. The EGR control device 24 controls the opening degree of the EGR valve 27 so that the target air amount tGa is supplied.

The target working gas amount calculation unit 79 calculates a target working gas amount tGwg (= tGa / (1-tη)) based on the target EGR rate tη and the target air amount tGa.
The correction value calculation unit 80 calculates the correction value CV of the basic target pressure PemS based on the deviation ΔGwg (= tGwg−Gwg) of the working gas amount Gwg with respect to the target working gas amount tGwg. The correction value calculation unit 80, for example, a first correction value obtained by multiplying the deviation ΔGwg by the proportional gain Kp (> 0) and a second correction value obtained by multiplying the integrated value of the deviation ΔGwg by the integral gain Ki (> 0). An addition value with the correction value is calculated as a correction value CV. The correction value calculation unit 80 calculates a correction value CV that increases the basic target pressure PemS when the target working gas amount tGwg is larger than the working gas amount Gwg, and the basic value when the target working gas amount tGwg is smaller than the working gas amount Gwg. A correction value CV that lowers the target pressure PemS is calculated.

The target pressure setting unit 81 sets a value obtained by adding the correction value CV to the basic target pressure PemS as the target pressure tPem.
The third calculation unit 53c substitutes the inflow temperature Tti, the inflow amount Gti, the outlet pressure Pte, and the target pressure tPem calculated in this way into the equation (1), so that the target opening area tA of the variable nozzle 28 is obtained. Is calculated.

With reference to FIG. 7, the operation of the control device 50 described above will be described.
The control device 50 described above calculates the correction value CV based on the deviation ΔGwg between the target working gas amount tGwg and the working gas amount Gwg, and uses the correction value CV to correct the basic target pressure PemS to the target pressure tPem. Set.

  Here, for example, when PM is excessively accumulated in a DPF (Diesel Particulate Filter) located downstream of the turbine 22, the pressure greater than the pressure loss ΔPep defined in the exhaust passage data 66 is downstream of the turbine 22. Loss occurs. In this case, the actual outlet pressure Pte is larger than the outlet pressure Pte calculated by the outlet pressure calculator 65. Therefore, even if the variable nozzle 28 is controlled with the basic target pressure PemS calculated using the calculated value of the outlet pressure Pte as the target pressure tPem, the actual expansion ratio in the turbine 22 becomes smaller than the basic expansion ratio πS. The workload of the charger 17 is reduced. As a result, the supercharged intake air has a lower pressure and a lower density as the pressure drops. Therefore, the EGR device 23 reduces the EGR amount Gr by controlling the EGR valve 27 in the valve closing direction so as to increase the volume flow rate Qa of the intake air in order to supply the engine 10 with air corresponding to the target air amount tGa. . As a result, the EGR rate η decreases and NOx tends to be generated, and the error between the target air amount tGa and the intake air amount Ga may increase due to a decrease in the boost pressure Pb.

  That is, in the engine system including the EGR device 23 that controls the EGR valve 27 so that the intake air amount Ga becomes the target air amount tGa, the deviation ΔGwg between the target working gas amount tGwg and the working gas amount Gwg is a turbocharger. 17 indicates excess or deficiency of work. The control device 50 optimizes the work amount of the turbocharger 17 by setting the pressure obtained by correcting the basic target pressure PemS with the correction value CV based on the deviation ΔGwg to the target pressure tPem.

  Therefore, as shown in FIG. 7, when the target pressure tPem is set higher than the basic target pressure PemS when the target working gas amount tGwg is larger than the working gas amount Gwg, the exhaust pressure Pem is increased and the turbo is increased. As the work amount of the charger 17 increases, the pressure of the EGR gas also increases. As a result, the pressure of the intake air after supercharging is increased, and control of the EGR valve 27 in the valve closing direction is suppressed, so that the EGR amount Gr increases. As a result, when the boost pressure Pb increases, the working gas amount Gwg supplied to the engine 10 increases, and the working gas having the target air amount tGa and the target EGR rate tη can be supplied to the engine 10.

According to the control apparatus 50 of the said embodiment, the effect enumerated below is acquired.
(1) The control device 50 increases the target pressure tPem when the target working gas amount tGwg is larger than the working gas amount Gwg, thereby supplying the engine 10 with working gas having the target air amount tGa and the target EGR rate tη. As a result, the EGR rate η can be increased while securing the amount of air necessary for fuel combustion, so that NOx and PM can be reduced.

  (2) The control device 50 calculates the target working gas amount tGwg based on the target EGR rate tη selected from the target EGR rate data 74 and the target air amount tGa selected from the target air amount data 76. According to such a configuration, the calculation of the target EGR rate tη and the target air amount tGa is simplified, and as a result, the calculation of the target working gas amount tGwg is simplified.

  (3) The basic expansion ratio selecting unit 70 calculates the basic target pressure PemS by multiplying the basic expansion ratio πS selected from the basic expansion ratio data 71 by the outlet pressure Pte calculated by the outlet pressure calculating unit 65. Thereby, the calculation of the basic target pressure PemS can be simplified.

In addition, the said embodiment can also be suitably changed and implemented as follows.
The basic expansion ratio only needs to be an expansion ratio suitable for the operating state of the engine 10, and is not limited to one selected by the engine speed Ne and the fuel injection amount Gf. For example, the engine speed Ne and the fuel injection amount In addition to Gf, the fuel injection amount Gf may be selected based on the amount of change in the fuel injection amount Gf, the amount of change in the accelerator opening, or the like.

  Since the EGR control device 24 calculates the target air amount tGa, the control device 50 may acquire the target air amount tGa by inputting a signal indicating the target air amount tGa from the EGR control device 24. Further, the control device 50 may calculate the target air amount tGa based on the fuel injection amount Gf and the target excess rate tλ that is a target value of the excess air rate λ based on the operating state of the engine 10. In this case, the control device 50 may acquire the target excess rate tλ by inputting a signal indicating the target excess rate tλ from the EGR control device 24 that has calculated the target excess rate tλ. That is, the control device 50 only needs to obtain the target air amount tGa having the same value as that of the EGR control device 24, and further simplifies the configuration by inputting parameters for obtaining the target air amount tGa from the EGR control device 24. Can be planned.

  When the EGR control device 24 calculates the target EGR rate tη, the control device 50 may acquire the target EGR rate tη by inputting a signal indicating the target EGR rate tη from the EGR control device 24. Thereby, the structure of the control apparatus 50 can be further simplified.

  The control device 50 may calculate the correction value CV when the target working gas amount tGwg is larger than the working gas amount Gwg. Therefore, the control device 50 may set the correction value CV to 0 when the target working gas amount tGwg is equal to or less than the working gas amount Gwg.

  The fuel injection control unit that controls the fuel injection amount Gf and the VNT control device 50 may be incorporated in the same control device. Moreover, the EGR control device 24 and the VNT control device 50 that control the opening degree of the EGR valve 27 may be incorporated in the same control device.

  DESCRIPTION OF SYMBOLS 10 ... Diesel engine, 17 ... Turbocharger, 18 ... Compressor, 19 ... Intercooler, 20 ... Exhaust passage, 21 ... Connecting shaft, 22 ... Turbine, 23 ... EGR device, 24 ... EGR control device, 25 ... EGR passage, 26 ... EGR cooler, 27 ... EGR valve, 28 ... variable nozzle, 29 ... actuator, 30 ... crankshaft, 31 ... intake air amount sensor, 33 ... EGR pressure sensor, 34 ... EGR temperature sensor, 36 ... boost pressure sensor, 37 ... actuation Gas temperature sensor, 38 ... engine speed sensor, 40 ... variable nozzle opening sensor, 41 ... atmospheric pressure sensor, 42 ... fuel injection control unit, 50 ... VNT control device, 50 ... control device, 51 ... control unit, 52 ... Acquisition unit, 53... Arithmetic unit, 53 a... First arithmetic unit, 53 b. ... 3rd calculating part, 54 ... Memory | storage part, 55 ... Nozzle drive part, 56 ... Working gas amount calculating part, 57 ... EGR amount calculating part, 58 ... EGR rate calculating part, 59 ... Inflow temperature calculating part, 60 ... Inflow temperature Data: 61 ... Inflow amount calculation unit, 62 ... EGR pressure loss calculation unit, 63 ... EGR passage data, 64 ... Exhaust pressure calculation unit, 65 ... Outlet pressure calculation unit, 66 ... Exhaust passage data, 70 ... Basic expansion ratio selection unit 71 ... Basic expansion ratio data, 72 ... Basic target pressure calculation unit, 73 ... Target EGR rate selection unit, 74 ... Target EGR rate data, 75 ... Target air amount selection unit, 76 ... Target air amount data, 79 ... Target operation Gas amount calculation unit, 80 ... correction value calculation unit, 81 ... target pressure setting unit.

Claims (4)

A part of the exhaust gas flowing into the turbine is recirculated to the intake passage, and the variable is applied to an engine system including an EGR device that controls the opening degree of the EGR valve so that the intake air amount of the engine becomes the target air amount. A control device for a capacity-type turbocharger,
A basic target pressure calculation unit for calculating a basic target pressure of exhaust gas flowing into the turbine;
A working gas amount calculating section for calculating a working gas amount sucked by the engine;
A target working gas amount calculation unit for calculating a target working gas amount that is a target amount of the working gas amount;
A correction value calculation unit that calculates a correction value of the basic target pressure according to a deviation between the target working gas amount and the working gas amount;
A target pressure setting unit for setting a value obtained by correcting the basic target pressure with the correction value as a target pressure;
A control unit that controls the opening of the variable nozzle so that the pressure of the exhaust gas flowing into the turbine becomes the target pressure,
The control unit for a variable displacement turbocharger, wherein the correction value calculation unit calculates the correction value for increasing the basic target pressure when the target working gas amount is larger than the working gas amount. 2. The variable capacity turbocharger control device according to claim 1, wherein the target working gas amount calculation unit calculates the target working gas amount using the target air amount and a target EGR rate that is a target value of an EGR rate. . A target EGR rate selection unit that selects the target EGR rate from target EGR rate data that defines the target EGR rate for each engine speed and fuel injection amount;
The variable capacity turbocharger according to claim 2, further comprising: a target air amount selection unit that selects the target air amount from target air amount data that defines the target air amount for each of the engine speed and the fuel injection amount. Control device. A basic expansion ratio selection unit that selects the basic expansion ratio from basic expansion ratio data that defines a basic expansion ratio for each engine speed and fuel injection amount;
An outlet pressure calculator that calculates an outlet pressure that is a pressure at an outlet of the turbine,
The control device for a variable displacement turbocharger according to any one of claims 1 to 3, wherein the basic target pressure calculation unit calculates the basic target pressure by multiplying the basic expansion ratio by the outlet pressure.

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