JP2005180404A - Variable nozzle type turbocharger control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize appropriate supercharged pressure in an EGR area in an engine having a variable nozzle type turbocharger. <P>SOLUTION: An engine ECU performs a program including a step (S130) selecting an EGR operation map in the EGR area, a step (S140) determining a target supercharged pressure based on the EGR operation map, a step (S150) calculating a nozzle opening when the target supercharged pressure is realized, a step (S160) outputting control signals to a DC servo motor which is an actuator for a nozzle valve, a step (S170) detecting a deviation between the target supercharged pressure and an actual supercharged pressure, and a step (S200) correcting the corrective amount of the control signals to the DC servo motor and data on the position sensor of the DC servo motor when the calculation of a mean deviation is completed (YES in S180) and the absolute value of the mean deviation is larger than a predetermined value (YES in S190). <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an internal combustion engine (engine) including a variable nozzle type turbocharger and an EGR (Exhaust Gas Recirculation) device, and in particular, taking into consideration the influence of deterioration over time of the variable nozzle type turbocharger. The present invention relates to an apparatus for controlling a variable nozzle turbocharger.

  There are two types of internal combustion engines for automobiles: naturally aspirated engines and supercharged engines. As the supercharging mechanism, an exhaust turbine drive type generally called a turbocharger and a mechanical drive type generally called a supercharger have been put into practical use. A turbocharger rotates a turbine with the energy of exhaust gas, compresses intake air with a compressor directly connected thereto, and supplies the compressed air to an engine. In an engine with a turbocharger, a waste gate valve that normally bypasses a part of exhaust gas flowing into the turbine is provided in order to prevent the supercharging pressure from becoming excessively large.

  If an abnormality occurs in the turbocharger and the operation is continued with the waste gate valve closed, the engine is put in an abnormal operation state, which may cause engine damage. Therefore, various techniques related to turbocharger abnormality detection have been proposed. For example, the boost pressure (supercharging pressure) on the compressor output side and the exhaust gas pressure on the turbine input side are detected, and when the boost pressure is lower than the exhaust gas pressure by a set value and the state continues for a set time, the turbocharger There is a technique for determining an abnormality.

  By the way, when the engine is in the low speed rotation region, the flow rate of the exhaust gas is small, so supercharging by the turbocharger is insufficient. As a countermeasure, a turbocharger that increases the kinetic energy given to the turbine rotor by reducing the opening, that is, the area of the turbine nozzle, has been developed. The variable nozzle type turbocharger is a kind of such turbocharger, and is provided with a plurality of rotatable nozzle vanes, and a turbine for guiding engine exhaust gas from a turbine nozzle formed between the nozzle vanes to a turbine rotor. The opening of the nozzle can be changed. In such a variable nozzle type turbocharger, the nozzle opening degree is controlled so as to achieve optimum supercharging pressure control according to the operating state.

  At this time, for example, the nozzle opening is feedback-controlled so that the target boost pressure determined by the accelerator opening (= engine load) and the engine speed is obtained. Also, an actuator (for example, a DC servo motor) that presets a nozzle opening map defined by the engine load and the engine speed, determines the nozzle opening from the map, and changes the nozzle opening. To control the nozzle opening.

  The engine may be provided with an EGR device for the purpose of reducing NOx (nitrogen oxide). In this EGR device, a passage for circulating the exhaust gas is provided between the exhaust manifold and the intake manifold, and the gas recirculation amount is adjusted by an EGR valve provided in the middle of the passage. Appropriate exhaust gas is recirculated from the exhaust manifold through the EGR passage to the intake manifold. At this time, as an index of the EGR amount, the EGR rate is defined as EGR rate = {EGR gas flow rate / (intake air flow rate + EGR gas flow rate)}, and the target value of the EGR rate depends on the engine load and the engine speed. It is determined. The opening degree of the EGR valve is feedback-controlled so as to achieve this target EGR rate.

  In a variable nozzle turbocharger, in order to detect abnormalities such as nozzle vane sticking (hereinafter referred to as nozzle stick) at a certain nozzle opening by supercharging pressure, all operating states and settings corresponding to each nozzle opening A value must be provided, and the abnormality determination process becomes very complicated. Japanese Patent Laid-Open No. 10-47071 (Patent Document 1) discloses a variable nozzle type turbocharger abnormality detecting device capable of easily detecting an abnormality caused by a nozzle stick in an engine equipped with a variable nozzle type turbocharger and an EGR device. Disclose. This variable nozzle type turbocharger abnormality detection device is a variable nozzle type turbo having a turbine driven by exhaust gas guided from a nozzle whose opening degree is variable according to an engine operating state, and a compressor driven by the turbine and compressing intake air. An EGR device that connects the charger, the exhaust system upstream of the turbine and the intake system via an EGR valve, sets a target value of the EGR amount according to the engine operating state, and feedback-controls the EGR valve is provided. In an internal combustion engine, an apparatus for detecting an abnormality of a variable nozzle turbocharger, wherein an EGR amount detecting means for detecting an actual value of an EGR amount, and an EGR amount actual value detected by the EGR amount detecting means is an EGR amount target value An abnormality that determines that the turbocharger is abnormal And a disconnection means.

  According to this variable nozzle type turbocharger abnormality detection device, when an abnormality occurs due to a nozzle stick or the like in the variable nozzle type turbocharger, the flow rate and pressure of the exhaust gas flowing through the turbine deviate from values suitable for the engine operating state. The amount of EGR is a value corresponding to the pressure difference before and after the EGR valve, that is, the difference between the pressure in the exhaust side EGR passage and the pressure in the intake side EGR passage. Here, the pressure in the exhaust side EGR passage is the exhaust gas pressure. Therefore, the nozzle stick can be detected by monitoring the deviation of the EGR amount. In this variable nozzle type turbocharger abnormality detection device, it is possible to easily determine the abnormality of the turbocharger by monitoring the deviation of the actual value of the EGR amount from the target value.

  The variable nozzle turbocharger also has the following problems. The variable nozzle type turbocharger is excessive due to differences between individual parts such as variations in manufacturing of actuators of the moving parts and turbocharger main parts (such as unison rings), or due to secular changes such as deterioration in durability due to use. For this reason, when the boost pressure is controlled to the target boost pressure, control with a preset operation amount causes a large change in the boost pressure (even if the same operation amount is applied). In some cases, the amount of operation of an actuator or the like that should be operated in accordance with that is different due to differences between individuals or aging). Even in such a case, it is possible to solve this problem by performing supercharging pressure feedback control. That is, the feedback control detects the deviation between the target supercharging pressure and the actual supercharging pressure, and determines the operation amount according to the deviation so as to eliminate this deviation. Even if individual variations or aging changes occur, these effects are absorbed and corrected in such control.

However, even in such feedback control, there are various problems that occur in the variable nozzle type turbocharger, and Patent Documents 2 to 4 disclose techniques for these.
Japanese Patent Laid-Open No. 10-47071 JP-A-1-290922 JP 60-228728 A Japanese Patent Laid-Open No. 1-139033

  As described above, feedback control is performed both in the variable nozzle turbocharger and in the EGR device. However, it is extremely difficult to perform feedback control in both at the same time. That is, in the variable nozzle turbocharger, the nozzle opening is feedback controlled so as to achieve the target supercharging pressure, while the EGR valve opening is controlled so as to achieve the target EGR rate on the EGR device side. become. When the nozzle opening degree of the variable nozzle turbocharger is changed, the intake air amount is changed, and the EGR rate is also changed as is apparent from the above-described definition formula. When the EGR valve is feedback-controlled in response to this change, there may be a contradictory control state on both sides, and it is extremely impractical to perform these feedback controls simultaneously.

  In such a case, for example, in the EGR region (the region where the engine coolant temperature is not low, where both the variable nozzle turbocharger and the EGR device are controlled), the nozzle opening of the variable nozzle turbocharger is not performed. Open loop control (having no return loop as in feedback control) is performed so that the degree becomes the nozzle opening determined from the map. At this time, since feedback control is not performed, even if individual variations such as actuators of the variable nozzle type turbocharger or changes with time occur, these effects are not absorbed by the feedback control.

  However, such a problem cannot be solved in any of the above-mentioned patent documents. That is, the above-mentioned Patent Documents 2 to 4 are related to the variable nozzle type turbocharger even if they are related to the EGR device, and the Patent Document 1 is related to the variable nozzle type turbocharger and the EGR device even if related to the nozzle stick. The abnormality is merely to be detected from the EGR amount and the EGR target amount that are feedback-controlled. In the region where the EGR device is feedback controlled, in the state where the variable nozzle turbocharger is not feedback controlled, even if the components of the variable nozzle turbocharger vary or change over time, these effects should be corrected. I can't. For this reason, if there are variations in components of the variable nozzle type turbocharger or changes over time, the actual supercharging pressure is different from the supercharging pressure determined from the map. For example, when wear occurs in a sliding portion such as a nozzle vane arm and a unison ring of a variable nozzle turbocharger, the nozzle vane (variable nozzle) receives torque on the opening side by the force of exhaust gas. For this reason, the turbine flow rate with respect to the opening command value of the variable nozzle increases due to wear over time. For this reason, the flow rate of the exhaust gas in the turbine is lowered, the turbine rotational speed is lowered, and the supercharging pressure is lowered. As a result, the exhaust performance and power performance of the engine do not express desired capabilities.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to realize an appropriate supercharging pressure in the EGR region in an internal combustion engine including an EGR device and a variable nozzle turbocharger. It is an object of the present invention to provide a variable nozzle type turbocharger control device that can be used.

  A variable nozzle turbocharger control device according to a first aspect of the present invention is a turbine driven by exhaust gas guided from a nozzle having a variable opening degree corresponding to the operating state of the internal combustion engine, and driven to a target supercharging pressure by the turbine. A variable nozzle type turbocharger having a compressor for compressing intake air and an exhaust system upstream of the turbine and an intake system are connected via an EGR valve, and an EGR amount target according to the operating state of the internal combustion engine A variable nozzle type turbocharger in an internal combustion engine having an EGR device that sets a value and performs feedback control of the EGR valve is controlled. This variable nozzle type turbocharger control device controls a calculation means for calculating a target supercharging pressure in an EGR operating region and an actuator for controlling the opening of the nozzle so as to correspond to the target supercharging pressure. Control means, detection means for detecting the actual boost pressure, and correction means for correcting the opening of the nozzle based on the deviation between the target boost pressure and the detected actual boost pressure. Including.

  According to the first aspect of the invention, in the internal combustion engine having the variable nozzle type turbocharger and the EGR device, the nozzle opening degree of the variable nozzle type turbocharger is not feedback controlled in the EGR operating region. The target boost pressure is calculated based on information (map) that defines the relationship between the rotational speed of the internal combustion engine and the load of the internal combustion engine and the target boost pressure in the EGR operating region. An actuator (for example, a DC servo motor) that controls the opening degree of the nozzle is controlled so as to achieve the calculated target boost pressure. At this time, since the feedback control of the EGR device is performed, the opening degree of the nozzle is the open loop control. In such a case, if the sliding part such as the nozzle vane arm and unison ring of the variable nozzle turbocharger is worn, the nozzle vane (variable nozzle) receives the torque on the opening side by the force of the exhaust gas, and is variable. The turbine flow rate is larger than the nozzle opening command value. That is, a deviation occurs between the command boost pressure and the actual boost pressure. Since the feedback control is not performed, this deviation remains. For example, the deviation is sampled a predetermined number of times by the detection means, and if the average value (more specifically, the absolute value of the average value) is larger than a predetermined threshold value, the correction means opens the nozzle. The degree is corrected so that the actual boost pressure approaches the target boost pressure. At this time, for example, information on the position of the sensor of the DC servo motor is corrected, or a command signal to the DC servo motor is corrected. As a result, even in the EGR region where feedback control cannot be performed and open loop control is performed, if there are variations in components of the variable nozzle turbocharger or changes over time, these effects can be corrected. As a result, it is possible to provide a variable nozzle type turbocharger control device capable of realizing an appropriate supercharging pressure in an EGR region in an internal combustion engine including an EGR device and a variable nozzle type turbocharger.

  In the variable nozzle turbocharger control device according to the second invention, in addition to the configuration of the first invention, the calculation means defines the relationship between the rotational speed of the internal combustion engine, the load of the internal combustion engine, and the target supercharging pressure. Means for calculating a target boost pressure based on the information obtained.

  According to the second aspect of the invention, the target boost pressure is calculated based on a three-dimensional map that defines the relationship between the engine speed and the load (injected fuel amount) of the internal combustion engine and the target boost pressure. The nozzle opening is controlled so that the target boost pressure is calculated.

  In the variable nozzle turbocharger control device according to the third invention, in addition to the configuration of the first or second invention, the correcting means includes means for correcting the position sensor of the actuator.

  According to the third aspect of the invention, the information relating to the position of the sensor of the servo motor, which is an example of the actuator, is corrected in order to correct the opening degree of the nozzle by the correcting means. As a result, even in the EGR region where feedback control cannot be performed and open loop control is performed, if there are variations in components of the variable nozzle turbocharger or changes over time, these effects can be corrected.

  In the variable nozzle turbocharger control device according to the fourth aspect of the invention, in addition to the configuration of the first or second aspect of the invention, the correction means includes means for correcting a command signal to the actuator.

  According to the fourth invention, the command signal to the servo motor which is an example of the actuator is corrected in order to correct the opening degree of the nozzle by the correcting means. As a result, even in the EGR region where feedback control cannot be performed and open loop control is performed, if there are variations in components of the variable nozzle turbocharger or changes over time, these effects can be corrected.

  In the variable nozzle type turbocharger control device according to the fifth invention, in addition to the configuration of any one of the first to fourth inventions, the correcting means includes a deviation between the target boost pressure and the detected actual boost pressure. Means for correcting the opening of the nozzle on the basis of the average value.

  According to the fifth invention, when the nozzle opening is corrected by the correcting means, the average value of the deviation between the target boost pressure and the detected actual boost pressure is used. Therefore, correction of the nozzle opening can be avoided by correction means based on a temporary erroneous detection of the actual supercharging pressure.

  In the variable nozzle type turbocharger control device according to the sixth aspect of the invention, in addition to the configuration of the fifth aspect of the invention, the correcting means is configured such that when the absolute value of the average value of deviations is greater than a predetermined value, Means for correcting the opening;

  According to the sixth invention, when correcting the nozzle opening degree by the correcting means, the absolute value of the average value of the deviation between the target boost pressure and the detected actual boost pressure is greater than a predetermined threshold value. It must be large. Therefore, correction of the nozzle opening can be avoided by correction means based on a temporary erroneous detection of the actual supercharging pressure.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same parts are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

  FIG. 1 is a diagram schematically showing an example of a diesel engine equipped with a variable nozzle turbocharger control device according to an embodiment of the present invention. The variable nozzle turbocharger control device is realized by an engine ECU (Electronic Control Unit) 1000 and a program executed by the engine ECU 1000.

Air necessary for combustion in the engine body 500 is filtered by the air cleaner 100, compressed by the compressor 320 of the turbocharger 300, cooled by the intercooler 120, and guided to the intake manifold 140. The intake air flow rate GA is adjusted by the throttle valve 130 and detected by the air flow meter 110. Further, the intake system is provided with an intake pipe pressure sensor 220 that detects an intake pipe pressure (boost pressure) PB, an intake pipe temperature sensor 230 that detects an intake pipe temperature TB, and an O ₂ sensor 240 that detects an excess air ratio λ. It has been. The engine body 500 is provided with a temperature sensor 510 that detects the temperature of engine cooling water. In the present embodiment, the value detected by the O ₂ sensor 240 is not directly used.

  Intake manifold 140 distributes intake air to each cylinder of engine body 500. The exhaust gas generated in each cylinder is collected by the exhaust manifold 160, then passed through the turbine 340 of the turbocharger 300, and finally purified by the catalytic converter 700 and discharged. In order to prevent an excessive supercharging effect by the turbocharger 300, an exhaust bypass passage 800 and a waste gate valve (WGV) 900 are provided so that the exhaust gas can bypass the turbine 340.

  In the turbine 340 of the turbocharger 300, a turbine rotor (also called a turbine wheel, a turbine blade, or the like) 350 is rotated by exhaust gas. Since the compressor blade 330 of the compressor 320 is connected to the turbine rotor 350 by the rotating shaft 310, the compressor blade 330 rotates with the turbine rotor 350 to compress the intake air, that is, has a supercharging action. As will be described in detail later, the turbine 340 is provided with a plurality of rotatable nozzle vanes 360 so that the opening, that is, the area of the turbine nozzle formed between the nozzle vanes 360 can be changed. Yes. Therefore, the turbine nozzle is called a variable nozzle. The opening degree of the variable nozzle is adjusted by an actuator (DC servo motor) 370.

  This engine is an engine with an EGR device for reducing NOx (nitrogen oxide), and a passage 150 for circulating exhaust gas is provided between the exhaust manifold 160 and the intake manifold 140. It has been. The gas recirculation amount is adjusted by an EGR valve 430 provided in the middle of the passage. The inside of the actuator 400 that drives the EGR valve 430 is partitioned into a negative pressure chamber 412 and an atmospheric pressure chamber 414 by a diaphragm 410. A spring 416 is housed in the negative pressure chamber 412 and biases the diaphragm 410 connected to the EGR valve 430 toward the valve closing side. The negative pressure adjusted by the negative pressure control valve 420 is introduced into the negative pressure chamber 412. When the negative pressure is introduced, the EGR valve 430 is lift-driven according to the magnitude of the negative pressure, and the exhaust gas corresponding to the lift amount is recirculated from the exhaust manifold 160 to the intake manifold 140 through the EGR passage 150. EGR is achieved.

  As described above, the EGR rate is defined as an EGR rate = {EGR gas flow rate / (intake air flow rate + EGR gas flow rate)} as an index of the EGR amount. The target value of the EGR rate is determined in advance by the engine load and the engine speed, and the EGR valve 430 is feedback controlled according to the target EGR rate.

Engine ECU 1000 receives signals from air flow meter 110, intake pipe pressure sensor 220, intake pipe temperature sensor 230, O ₂ sensor 240, and temperature sensor 510, and based on these signals, intake air flow rate GA, intake air The pipe pressure (boost pressure) PB, the intake pipe temperature TB, the excess air ratio λ, and the engine coolant temperature TE are detected. Engine ECU 1000 controls variable nozzle actuator 370 and EGR actuator 420 based on the detected data. Further, engine ECU 1000 controls the amount of fuel to be injected into engine body 500.

  2 is a cross-sectional view of a turbocharger 300 that is a variable nozzle type turbocharger, FIGS. 3A and 3B are views of the turbocharger 300 with the nozzle vane 360 opened, and FIGS. FIG. 5B shows a state in which the nozzle vane 360 in the turbocharger 300 is closed.

  With reference to these drawings, nozzle opening control of the turbocharger 300 will be described. A nozzle vane 360 provided on the turbine 340 side is an object of nozzle opening degree control. A plurality of (13 in this embodiment) rotatable nozzle vanes 360 are provided in the gas passage at the turbine inlet for introducing the exhaust gas to the turbine rotor 350. The opening degree of the variable nozzle formed between the nozzle vanes 360 is adjusted by rotating the drive arm 382 via the link 390, and the link 390 is connected to the rod 392 of the actuator 370. ing. Actuator 370 is a DC servo motor, for example.

  The driving force from the actuator 370 controlled by the engine ECU 1000 is transmitted in the order of the rod 392, the link 390, the unison ring 380, and the driving arm 382. The rod 392 expands and contracts by the action of the actuator 370. The unison ring 380 is rotated by the driving force transmitted from the rod 392. When the driving arm 382 rotates around the point X by the rotation of the unison ring 380, the nozzle vane 360 disposed on the back side of the driving arm 382 similarly rotates around the point X. Thereby, the flow velocity and pressure of the exhaust gas input to the turbine can be adjusted.

  In the engine low and medium speed rotation region, the rise of the supercharging pressure and the supercharging pressure are increased by restricting the nozzle passage and increasing the exhaust gas flow velocity, thereby reducing black smoke and improving torque (FIG. 3 ( A) and FIG. 3 (B)).

  In the engine high-speed rotation range, the nozzle passage is opened to lower the exhaust pressure, thereby improving fuel consumption and output and preventing over-rotation of the turbine 340 (FIGS. 4A and 4B).

  Further, in the region where the EGR device is operating, the nozzle opening is adjusted in order to stabilize the EGR control. At this time, the supercharging pressure is determined using a predetermined map (for example, a map for determining the supercharging pressure based on the engine load and the engine speed) so that the nozzle opening corresponding to the supercharging pressure is obtained. Controlled (At this time, feedback control is not performed). When the EGR is stopped (for example, when the engine coolant temperature is low), the target boost pressure corresponding to the engine operating state is calculated, and the output from the intake pipe pressure sensor 220 that detects the intake pipe pressure PB is the target excess pressure. The nozzle opening is feedback controlled so that the supply pressure is reached.

  As described above, in the EGR operation region, the opening degree control of the nozzle is performed based on the map, and the feedback control is performed in the EGR non-operation region.

  With reference to FIG. 5, a supercharging pressure map stored in the memory of engine ECU 1000 will be described. FIG. 5 is a supercharging pressure map when the EGR device is in an inoperative state. As shown in FIG. 5, the supercharging pressure map in the EGR non-operating state is represented by a three-dimensional map showing the relationship between the engine load (fuel injection amount), the engine speed and the supercharging pressure. When the supercharging pressure map shown in FIG. 5 is used, the EGR device is in a non-operating state, and the target supercharging pressure is calculated from the supercharging pressure map based on the engine load and the engine speed. The nozzle circuit is feedback-controlled so that the target boost pressure map is obtained.

  FIG. 6 shows a supercharging pressure map when the EGR device is in an operating state. As in FIG. 5, in FIG. 6, the relationship between the engine load (fuel injection amount), the engine speed and the supercharging pressure is represented by a three-dimensional map. Referring to FIG. 5 and FIG. 6, although all the supercharging pressure maps have the same tendency, the supercharging pressure values differ in the details. The supercharging pressure map at the time of EGR operation of FIG. 6 is used when the EGR device is operating and the EGR device is feedback controlling the EGR valve 430, and the opening degree of the nozzle vane 360 of the turbocharger 300 Is open-loop controlled.

  Further, as shown in FIG. 7, an EGR rate may be used instead of the supercharging pressure on the vertical axis of the supercharging pressure map shown in FIG.

  With reference to FIG. 8, a control structure of a program executed by engine ECU 1000 that realizes the variable nozzle turbocharger control device according to the present embodiment will be described.

  In step (hereinafter step is abbreviated as S) 100, engine ECU 1000 detects the engine speed and the engine load. At this time, the engine speed and the engine load are detected based on information input from the engine speed sensor and the fuel injection amount sensor. In S110, engine ECU 1000 detects the engine coolant temperature based on the information input from temperature sensor 510. In S120, engine ECU 1000 determines whether or not it is in the EGR operating region. This determination is made based on, for example, the engine coolant temperature detected in S110. The EGR operating region is generally an EGR non-operating region when the engine coolant temperature is low. If it is in the EGR operating region (YES in S120), the process proceeds to S130. If not (NO in S120), the process proceeds to S230.

  In S130, engine ECU 1000 selects an EGR operation map. At this time, the map shown in FIG. 6 is selected. In S140, engine ECU 1000 determines a target boost pressure. At this time, using the map shown in FIG. 6, the target boost pressure is determined based on the engine load and engine speed detected in S100.

  In S150, the engine ECU calculates a nozzle opening corresponding to the target boost pressure. In S160, ECU 1000 outputs a control signal to actuator (DC servo motor) 370 of nozzle vane 360. At this time, a control signal is output to the DC servo motor so as to realize the nozzle opening calculated in S150. In S170, engine ECU 1000 detects a deviation between the target boost pressure and the actual boost pressure. In S180, engine ECU 1000 determines whether or not the calculation of the average deviation has been completed. For example, the deviation is detected at a predetermined sampling time, and when the deviation is detected, for example, 10 times, the average value of the deviation is calculated, and it is determined that the calculation of the average deviation is completed. When calculation of the average deviation is completed (YES in S180), the process proceeds to S190. If not (NO in S180), the process proceeds to S140.

  In S190, engine ECU determines whether or not | average deviation |> threshold value. That is, it is determined whether or not the absolute value of the average deviation calculated in S180 is larger than a predetermined threshold value. If | average deviation |> threshold value (YES in S190), the process proceeds to S200. Otherwise (NO in S190), this process ends.

  Although the processing in S180 and S190 is described as being performed in the case of the EGR operating region (YES in S120), the present invention is not limited to this. In the EGR non-operating region, it may be more accurate to perform the processes in S180 and S190. That is, in the EGR operating region, even though the processing of S180 and S190 can be physically performed, it is affected by the EGR amount, but is not affected in the EGR non-operating region. .

  In S200, engine ECU 1000 calculates the correction amount of the control signal to the DC servo motor. The calculated correction amount of the control signal is reflected in the processing in S160 at the next trip. Although the correction amount of the control signal to the DC servo motor is calculated in S200, the present invention is not limited to this. For example, the position sensor of the DC servo motor is allocated to the average deviation. You may make it correct | amend only.

  In S230, engine ECU 1000 selects the EGR non-operation map. At this time, the map shown in FIG. 5 is selected. In S240, engine ECU 1000 determines a target boost pressure. At this time, the target boost pressure is determined based on the engine load and the engine speed based on the map shown in FIG. In S250, the nozzle opening degree that achieves the target boost pressure determined in S240 is calculated. In S260, engine ECU 1000 outputs a control signal to actuator (DC servo motor) 370 that operates nozzle vane 360 of turbocharger 300.

  In S270, engine ECU 1000 detects a deviation between the target boost pressure and the actual boost pressure. In S300, the engine ECU executes feedback control so that the deviation detected in S270 is zero. At this time, since the EGR device is not operating and the EGR device is not executing feedback control, the opening degree of the nozzle vane 360 of the variable nozzle turbocharger is feedback controlled.

  In S400, engine ECU 1000 determines whether or not learning control based on deviation is necessary. That is, when feedback control is performed on the opening degree of the nozzle vane 360 in a non-operating state of EGR, learning control is required when a deviation during feedback control remains due to deterioration of the components of the turbocharger 300 over time. It is judged. If it is determined that learning control is necessary (YES in S400), the process proceeds to S500. Otherwise (NO in S400), this process ends.

  In S500, engine ECU 1000 corrects the supercharging pressure map (EGR non-operation) and supercharging pressure map (EGR operation) based on the state quantity (deviation) during feedback control.

  An operation of engine ECU 1000 that realizes the variable nozzle turbocharger control device according to the present embodiment based on the above-described structure and flowchart will be described.

  When the engine is operating, the engine speed and the engine load are detected (S100). The engine coolant temperature is detected (S110), and it is determined based on the engine coolant temperature and other conditions whether or not it is in the EGR operating region (S120). If not in the EGR operating region (NO in S120), the EGR non-operating map (FIG. 5) is selected (S230). A target boost pressure is determined based on the map shown in FIG. 5 (S240), the nozzle opening is calculated (S250), and a control signal is output to the DC servo motor (S260). The DC servo motor is an actuator 370 of the nozzle vane 360, and the DC servo motor is operated based on a control signal output from the engine ECU 1000 to control the opening degree of the nozzle vane 360. Based on the opening degree, the turbocharger 300 is operated, the intake air is compressed, and the actual supercharging pressure is detected by the intake pipe pressure sensor 220 via the intercooler 120. A deviation between the target boost pressure and the actual boost pressure is detected (S270), and feedback control by, for example, PID control is executed so that this deviation becomes zero (S300).

  During feedback control (S300), components of the turbocharger 300 have deteriorated over time, etc., and the control signal to the DC servo motor is accurate, but the nozzle opening does not operate correctly. Therefore, a deviation or the like in the feedback control remains. If this deviation is detected and it is determined that learning control based on the deviation is necessary (YES in S400), the supercharging pressure maps shown in FIGS. 5 and 6 are corrected.

  On the other hand, if it is determined that the engine is in the EGR operating region based on the engine coolant temperature or the like (YES in S120), the EGR operating map shown in FIG. 6 is selected (S130). A target boost pressure is determined based on the boost pressure map shown in FIG. 6 (S140), and the nozzle opening is calculated (S150). A control signal is output from engine ECU 1000 to the DC servo motor that is actuator 370 of nozzle vane 360 so as to realize the nozzle opening calculated in S150 (S160).

  The deviation between the target boost pressure and the actual boost pressure is detected in the same manner as when the EGR is inactive (S170). Such a process is repeated 10 times, for example, and an average value (average deviation) of the deviations is calculated. When the calculation of the average deviation is completed (YES in S180), it is determined whether or not the absolute value of the average deviation is larger than a predetermined threshold value. If the absolute value of the average deviation is greater than the predetermined average value (YES in S190), for example, the components constituting turbocharger 300 deteriorate and DC servo motor corresponding to the target boost pressure in open loop control Even if the control signal is output, the predetermined nozzle opening is not reached. Therefore, the correction amount of the control signal to the DC servo motor is calculated, and the control signal to the DC servo motor is calculated in consideration of the correction amount at the next trip, or the data about the position sensor of the DC servo motor is obtained. Correction is made based on the average deviation (S200).

  As described above, according to the variable nozzle turbocharger control device according to the present embodiment, in the engine having the variable nozzle turbocharger and the EGR device, the nozzle opening of the variable nozzle turbocharger is performed in the EGR operating region. Open loop control is performed without feedback control. The target boost pressure is calculated based on a map that defines the relationship between the engine speed and the engine load and the target boost pressure in the EGR operating region. The opening degree of the nozzle of the turbocharger is controlled so as to achieve the calculated target supercharging pressure. At this time, a DC servo motor may be controlled as an actuator. In such a case, since the feedback control of the EGR device is performed, the opening degree of the nozzle is the open loop control. In such a case, if the sliding portion between the nozzle vane arm and the unison ring of the variable nozzle turbocharger is worn, the nozzle vane does not have an opening corresponding to the target supercharging pressure. That is, a deviation occurs between the target boost pressure and the actual boost pressure. Since the feedback control is not performed, this deviation remains. When such a deviation is repeatedly detected, based on the average value of these deviations, for example, when the nozzle opening is difficult to close, the control signal to the DC servo motor is corrected so that it is more closed, The data of the position sensor of the DC servo motor is corrected. As a result, in an engine equipped with an EGR device and a variable nozzle turbocharger, an appropriate supercharging pressure can be realized in the EGR region.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

It is a schematic block diagram of an engine system provided with the variable nozzle type turbocharger control apparatus which concerns on this Embodiment. It is sectional drawing of a variable nozzle type turbocharger. It is FIG. (1) for demonstrating the function of a variable nozzle type turbocharger. It is FIG. (2) for demonstrating the function of a variable nozzle type turbocharger. It is a figure which shows a supercharging pressure map (EGR non-operation). It is a figure which shows a supercharging pressure map (EGR operation | movement). It is a figure which shows a supercharging pressure map (EGR rate). It is a flowchart which shows the control structure of the program performed by engine ECU which implement | achieves a variable nozzle type turbocharger control apparatus.

Explanation of symbols

100 air cleaner, 110 air flow meter, 120 intercooler, 130 throttle valve, 140 intake manifold, 150 passage, 160 exhaust manifold, 220 intake pipe pressure sensor, 230 intake pipe temperature sensor, 240 O ₂ sensor, 300 turbocharger, 310 rotating shaft, 320 compressor, 330 compressor blade, 340 turbine, 350 turbine rotor, 360 nozzle vane, 370 actuator (DC servo motor), 380 unison ring, 382 drive arm, 390 link, 392 rod, 400 actuator, 410 diaphragm, 412 negative pressure chamber, 414 Atmospheric pressure chamber, 416 spring, 430 EGR valve, 500 engine body, 510 temperature sensor, 700 catalytic converter, 800 exhaust by Scan path 900 wastegate valve (WGV), 1000 engine ECU.

Claims (6)

A variable nozzle type having a turbine driven by exhaust gas guided from a nozzle having a variable opening degree corresponding to the operating state of the internal combustion engine and a compressor driven by the turbine and compressing intake air so as to achieve a target supercharging pressure An EGR that connects a turbocharger, an exhaust system upstream of the turbine, and an intake system via an EGR valve, and sets a target value of an EGR amount according to an operating state of the internal combustion engine to feedback-control the EGR valve A control device for a variable nozzle type turbocharger in an internal combustion engine comprising:
A calculation means for calculating a target boost pressure in the EGR operating region;
Control means for controlling an actuator for controlling the opening of the nozzle so as to correspond to the target supercharging pressure;
Detection means for detecting the actual supercharging pressure;
A variable nozzle type turbocharger control device, comprising: correction means for correcting the opening degree of the nozzle based on a deviation between the target supercharging pressure and the detected actual supercharging pressure.   2. The calculation means according to claim 1, wherein the calculation means includes means for calculating the target boost pressure based on information defining a relationship between a rotational speed of the internal combustion engine and a load of the internal combustion engine and the target boost pressure. Variable nozzle turbocharger controller.   The variable nozzle turbocharger control device according to claim 1, wherein the correction means includes means for correcting a position sensor of the actuator.   The variable nozzle turbocharger control device according to claim 1, wherein the correction means includes means for correcting a command signal to the actuator.   The said correction | amendment means includes any means for correct | amending the opening degree of the said nozzle based on the average value of the deviation of the said target supercharging pressure and the detected actual supercharging pressure. The variable nozzle type turbocharger control device described in 1. 6. The variable nozzle turbocharger control according to claim 5, wherein the correction means includes means for correcting the opening degree of the nozzle when the absolute value of the average value of the deviations is larger than a predetermined value. apparatus.

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