JP2007321687A - Control device for turbocharged internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control device capable of acquiring rotation speed of rotary shaft of a turbocharger without providing a rotation speed sensor on the turbocharger in an internal combustion engine provided with the turbocharger supercharging suction air. <P>SOLUTION: A throttle valve 13 is provided in a suction pipe 11 in the engine 10 and a suction pressure sensor 14 detecting suction pressure is provided in a downstream thereof. A atmospheric pressure sensor 16 is provided on the most upstream part of the suction pipe 11, and the turbocharger 20 is provided in a downstream thereof. In this structure, an engine ECU 30 calculates rotation speed of the rotary shaft of the turbocharger 20 based on inlet pressure and outlet pressure of the turbocharger 20. Atmospheric pressure detected by the atmospheric pressure sensor 16 is defined as inlet pressure here. Also, pressure change in the suction pipe 11 in a downstream of the turbocharger 20 is modeled and outlet pressure is calculated from suction pressure detected by the suction pressure sensor 14 by using reverse model thereof. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a control device for an internal combustion engine with a turbocharger, and relates to an apparatus for acquiring the rotational speed of a turbocharger.

  A turbocharger is generally known as a supercharger that supercharges intake air using exhaust power. In recent years, an electric turbocharger has been developed that attaches an electric motor to the rotating shaft of a turbocharger and assists the power of the turbocharger according to the operating state of the internal combustion engine. In this case, by performing the power assist by the electric motor, the turbocharger is supercharged and the supercharging effect is improved.

  As an electric motor for such an electric turbocharger, there is one using an induction motor (see, for example, Patent Document 1). The induction motor includes a rotor attached to a rotating shaft of a turbocharger and a stator provided on the outer peripheral side thereof, and the stator includes a plurality of exciting coils. Then, by controlling the energization to each excitation coil according to the rotation speed of the rotation shaft, the rotation is assisted by the rotation shaft.

In Patent Document 1, a rotation speed sensor is provided on the rotation shaft in order to know the rotation speed of the rotation shaft of the turbocharger. However, since the rotational speed sensor is affected by high-temperature exhaust heat or work heat generated by compression of intake air, heat resistance is required and the sensor cost is increased. Moreover, since it is located in the vicinity of the induction motor, the reliability of the detection result may be reduced due to the influence of electromagnetic noise generated with the power supply of the induction motor.
JP 2005-42684 A

  A main object of the present invention is to provide a control device capable of obtaining a rotational speed of a rotating shaft of an internal combustion engine having a turbocharger that supercharges intake air without relying on a rotational speed sensor for the turbocharger. To do.

  Hereinafter, means for solving the above-described problems and the effects thereof will be described.

  According to the first aspect of the present invention, a turbine wheel that is rotated by exhaust energy and a compressor impeller that is coupled to the turbine wheel via a rotating shaft are provided, and the intake air is compressed by the rotation of the compressor impeller to be supercharged. It is assumed that the present invention is applied to an internal combustion engine equipped with a turbocharger that performs the above. Such a control device for an internal combustion engine includes means for acquiring the inlet pressure of the compressor impeller and means for acquiring the outlet pressure, and associates the rotational speed of the rotating shaft with the pressure ratio between the inlet pressure and the outlet pressure of the compressor impeller. Storage means for storing. Then, the rotational speed of the rotating shaft of the turbocharger is derived from the acquired inlet pressure and outlet pressure of the compressor impeller and the correspondence stored in the storage means.

  The present inventor has confirmed that the rotational speed of the rotating shaft of the turbocharger has a correlation with the pressure ratio between the inlet pressure and the outlet pressure of the compressor impeller. Specifically, it was confirmed that the pressure ratio (outlet pressure / inlet pressure) was small when the rotation speed of the rotation shaft was small, and the pressure ratio was increased as the rotation speed of the rotation shaft was increased. By storing this relationship, it is possible to derive the rotation speed of the rotation shaft without depending on the rotation speed sensor.

  The inventors of the present application have also confirmed that the rotational speed of the rotating shaft is hardly affected by engine operating conditions (such as the pressure condition on the turbine wheel side) other than the pressure ratio between the inlet pressure and the outlet pressure of the compressor impeller. For this reason, the cost required for adaptation for defining the correlation between the rotational speed of the rotating shaft and the pressure ratio can be reduced.

  According to the second aspect of the present invention, the present invention is applied to an internal combustion engine having an atmospheric pressure sensor for detecting atmospheric pressure, and the pressure detected by the atmospheric pressure sensor is calculated as the inlet pressure of the compressor impeller.

  The intake air introduced into the compressor impeller is almost the atmosphere itself, and the inlet pressure of the compressor impeller is almost equal to the atmospheric pressure. For this reason, it is possible to use the pressure detected by the atmospheric pressure sensor as the inlet pressure of the compressor impeller.

  Generally, in the output control of an internal combustion engine, the air density of intake air is used as a control parameter, and it is necessary to know the atmospheric pressure in order to obtain the air density. For this reason, the atmospheric pressure sensor is usually equipped. Therefore, according to the present invention, it is possible to know the inlet pressure of the compressor impeller using an existing sensor without adding a pressure sensor.

  According to a third aspect of the present invention, there is provided a turbine wheel that is rotated by exhaust energy, and a compressor impeller that is coupled to the turbine wheel via a rotating shaft, and the intake air is compressed by the rotation of the compressor impeller to be supercharged. It is assumed that the present invention is applied to an internal combustion engine equipped with a turbocharger that performs the above. Such a control device for an internal combustion engine includes means for acquiring the outlet pressure of the compressor impeller, and storage means for storing the rotational speed of the rotating shaft in association with the outlet pressure of the compressor impeller. Then, the rotational speed of the rotating shaft of the turbocharger is derived from the acquired outlet pressure of the compressor impeller and the correspondence stored in the storage means.

  As described above, the inlet pressure of the compressor impeller is substantially equal to the atmospheric pressure. For this reason, it is possible to derive the rotational speed of the rotating shaft of the turbocharger only by the outlet pressure of the compressor impeller, ignoring such fluctuations in atmospheric pressure.

  The invention according to claim 4 is applied to an internal combustion engine having a turbocharger having an induction motor capable of assisting the rotation of the rotation shaft of the turbocharger, and controls the induction motor using the derived rotation speed of the rotation shaft. It is characterized by comprising control means for

  In a so-called electric turbocharger, the supercharging effect can be improved by assisting the rotation of the rotating shaft of the turbocharger by the electric motor. However, when the rotation of the rotating shaft is assisted by the induction motor, it is necessary to supply power to the induction motor according to the rotation speed of the rotating shaft. In this case, if the rotation speed sensor is provided on the rotation shaft, the reliability of the detection result of the rotation speed sensor may be lowered due to the influence of electromagnetic noise generated by driving the induction motor. In this regard, according to the present invention, since the means for deriving the shaft rotation speed is provided, the shaft rotation speed can be obtained without being affected by electromagnetic noise unlike the rotation speed sensor. And it is possible to drive an induction motor appropriately according to the rotational speed.

  In the invention according to claim 5, a throttle valve capable of adjusting the amount of intake air downstream of the compressor impeller in the intake passage of the internal combustion engine, and an intake pressure sensor capable of detecting the pressure of intake air downstream of the throttle valve; It is assumed that the present invention is applied to an internal combustion engine equipped with Then, the outlet pressure of the compressor impeller is calculated from the pressure of the intake air detected by the intake pressure sensor using the relationship of the pressure change in the intake passage defined in advance.

  In the internal combustion engine of the present invention, the intake air amount is adjusted by the throttle valve, and the pressure of the intake air sucked into the internal combustion engine is detected by the intake pressure sensor. In this case, the intake air is throttled by the throttle valve and sucked into the internal combustion engine, so that the intake pressure detected by the intake pressure sensor is different from the outlet pressure of the compressor impeller. Therefore, it is preferable to predetermine the relationship between pressure changes in the intake pipe. By using this defined relationship, the outlet pressure of the compressor impeller can be obtained from the intake pressure downstream of the throttle valve detected by the intake pressure sensor.

  Since the intake pressure sensor is usually installed to know the intake air amount of the internal combustion engine, etc., according to the present invention, the outlet pressure of the compressor impeller can be known using the existing sensor.

  According to the sixth aspect of the present invention, the throttle passing air that passes through the throttle valve section based on the pressure of the intake air downstream of the throttle valve detected by the intake pressure sensor, the intake air amount of the internal combustion engine, and the temperature of the intake air. Calculate the flow rate. Then, the compressor impeller outlet pressure is calculated based on the throttle passing air flow rate, the throttle valve opening area, the intake air pressure downstream of the throttle valve detected by the intake pressure sensor, and the intake air temperature.

  In short, the pressure change in the intake passage described above is caused by intake air being throttled by the throttle valve and sucked into the internal combustion engine. Therefore, using the known parameters (intake air amount of the internal combustion engine) and parameters detectable by various sensors (intake air pressure and intake air temperature downstream of the throttle valve), the mode of pressure change in the intake passage is calculated. By doing so, the outlet pressure of the compressor impeller can be obtained.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, an embodiment of the invention will be described with reference to the drawings. In the present embodiment, an engine control system is constructed for an in-vehicle multi-cylinder diesel engine, and the engine of the control system is provided with a turbocharger with an induction motor. First, the overall schematic configuration of the engine control system will be described with reference to FIG.

  In the engine 10 shown in FIG. 1, the intake pipe 11 is provided with a throttle valve 13 whose opening degree is adjusted by a throttle actuator 12 such as a DC motor. The throttle actuator 12 incorporates a throttle opening sensor for detecting the throttle opening. An intake pressure sensor 14 for detecting the intake pressure on the downstream side of the throttle and an intake air temperature sensor 15 for detecting the temperature of the intake air are provided on the downstream side of the throttle valve 13. The intake pipe 11 is branched downstream of the throttle valve 13 and connected to the intake port of each cylinder of the engine 10. An atmospheric pressure sensor 16 for detecting atmospheric pressure is provided at the most upstream portion of the intake pipe 11 and an air cleaner 17 is provided downstream thereof. The intake pressure sensor 14 and the atmospheric pressure sensor 16 are generally equipped to obtain the intake air amount and intake air density of the engine 10.

  An electric turbocharger 20 is provided downstream of the air cleaner 17 in the intake pipe 11. Here, the configuration of the electric turbocharger 20 will be described with reference to FIG. As shown in FIG. 2, the electric turbocharger 20 includes a compressor impeller 21 provided in the intake pipe 11 and a turbine wheel 22 provided in an exhaust pipe (not shown). These are connected by a shaft 23 and accommodated in a housing 24. With this configuration, the turbine wheel 22 is rotated by the exhaust gas flowing through the exhaust pipe, and the rotational force is transmitted to the compressor impeller 21 via the shaft 23. As a result, the compressor impeller 21 rotates and the intake air flowing through the intake pipe 11 is compressed to perform supercharging.

  The electric turbocharger 20 is provided with an induction motor 25 that assists the rotation of the shaft 23. Specifically, a rotor (rotor) 26 is provided on the shaft 23, and a stator (stator) 27 including a multiphase excitation coil is provided on a housing 24 on the outer peripheral side of the rotor 26. In such a configuration, by energizing the exciting coil of the stator 27, a rotational force is applied to the shaft 23, and the supercharging effect of the electric turbocharger 20 is increased.

  Returning to the description of FIG. 1, the engine ECU 30 is configured mainly by a microcomputer including a CPU, a ROM, a RAM, and the like. In addition to the intake pressure sensor 14, the intake air temperature sensor 15, and the atmospheric pressure sensor 16 described above, detection signals are sequentially input to the engine ECU 30 from various sensors that detect engine rotation speed and accelerator operation amount. Then, the engine ECU 30 appropriately controls the throttle actuator 12 and the like based on the input engine operation information.

  In addition, the engine ECU 30 performs power assist control by the induction motor 25 so as to quickly obtain a desired supercharging pressure during vehicle acceleration. Specifically, the target assist power and power assist timing are calculated based on the target boost pressure and intake air amount, and the calculation results are output to the motor ECU 40. The motor ECU 40 receives a signal from the engine ECU 30 and controls power supply to the induction motor 25 in consideration of motor efficiency and the like. Specifically, the motor ECU 40 is connected to a battery 41, and energizes each excitation coil of the stator 27 from the battery 41 according to the rotation speed of the shaft 23 (hereinafter referred to as the shaft rotation speed).

  That is, in order to drive the induction motor 25 in the power assist control, it is necessary to know the shaft rotation speed. As this method, for example, it is conceivable to provide a rotational speed sensor on the shaft 23 and use the detection result. However, in that case, the rotational speed sensor must withstand the work heat generated by the compression of the intake air and the high-temperature exhaust heat, and the sensor cost increases accordingly. Further, since it is provided in the vicinity of the induction motor 25, it is easily affected by electromagnetic noise generated during its driving, and the reliability of the detection result is lowered.

  In order to solve this problem, the present inventor considered obtaining the shaft rotation speed without using the rotation speed sensor. The pressure ratio between the intake pressure at the inlet of the compressor impeller 21 (hereinafter referred to as compressor inlet pressure) and the intake pressure at the downstream side (hereinafter referred to as compressor outlet pressure) has a correlation with the shaft rotational speed. It was confirmed. FIG. 3 is a graph showing the relationship between the pressure ratio (compressor outlet pressure / compressor inlet pressure) and the shaft rotation speed. As shown in FIG. 3, the shaft rotation speed increases as the pressure ratio increases. The inventor of the present application has confirmed that the correlation is hardly affected by the engine operating state other than the compressor inlet pressure and the outlet pressure and the exhaust system of the turbocharger 20. Therefore, in the present embodiment, paying attention to such a relationship, the shaft rotation speed is acquired without using the rotation speed sensor.

  Hereinafter, a method for calculating the compressor inlet pressure P1c and the compressor outlet pressure P2c will be described.

  First, a method for calculating the compressor inlet pressure P1c will be described. In the present embodiment, attention is paid to the atmospheric pressure Patm detected by the atmospheric pressure sensor 16 as the compressor inlet pressure P1c. In short, although the air cleaner 17 is provided between the atmospheric pressure sensor 16 and the turbocharger 20, the pressure loss due to the air cleaner 17 is small and almost negligible. Therefore, in the present embodiment, the atmospheric pressure Patm is set as the compressor inlet pressure P1c.

  Next, a method for calculating the compressor outlet pressure P2c will be described. In the present embodiment, changes in the flow rate and pressure of intake air in the intake pipe 11 are modeled, and the compressor outlet pressure P2c is calculated from the intake pressure Pim detected by the intake pressure sensor 14 by using the model.

  The air flow rate d (m_thr) / dt per unit time passing through the throttle valve 13 in the intake pipe 11 is the compressor outlet pressure P2c that is the upstream intake pressure and the intake pressure Pim that is the downstream intake pressure. And is expressed by the following equation.

ここで、Ａ＿ｔｈｒはスロットル有効断面積（スロットルバルブ１３部の開口面積）であり、Ｒは気体定数、Ｔは吸気温、κは比熱比である。

Here, A_thr is a throttle effective sectional area (opening area of the throttle valve 13 portion), R is a gas constant, T is an intake air temperature, and κ is a specific heat ratio.

  Further, the minute change amount dPim of the intake pressure Pim is the engine intake obtained from the throttle passage air flow rate d (m_thr) / dt obtained by the equation (1), the engine speed, the intake pressure Pim, and the charging efficiency. It is expressed by the following expression using the time differential value d (m_e) / dt of the air amount m_e.

ここでＶｉｎｔａｋｅはスロットルバルブ１３とエンジン１０との間の吸気管１１の内容積であり、Ｒは気体定数、Ｔは吸気温である。

Here, Vintake is the internal volume of the intake pipe 11 between the throttle valve 13 and the engine 10, R is a gas constant, and T is the intake air temperature.

  FIG. 4 shows a throttle model that obtains an air flow rate d (m_thr) / dt per unit time that passes through the throttle valve 13 by equation (1), and an intake pipe model that obtains intake pressure Pim by integrating equation (2). Is a diagram showing a calculation block for obtaining the intake pressure Pim from the compressor outlet pressure P2c. As shown in FIG. 4, the compressor outlet pressure P2c is related to the intake pressure Pim using the throttle effective sectional area A_thr, the intake air temperature T, the engine intake air amount m_e, the throttle model, and the intake pipe model.

  Therefore, in the present embodiment, the compressor outlet pressure P2c is calculated from the intake pressure Pim by reversely calculating the calculation block for obtaining the intake pressure Pim from the compressor outlet pressure P2c shown in FIG. FIG. 5 shows a calculation block diagram for obtaining the compressor outlet pressure P2c from the intake pressure Pim using the inverse models of the throttle model and the intake pipe model. That is, in the present embodiment, the compressor outlet pressure P2c is calculated using the intake pressure Pim, the engine intake air amount m_e, the intake air temperature T, the throttle effective sectional area A_thr, the intake pipe inverse model, and the throttle inverse model. In this case, the intake pipe inverse model is an inverse function of the throttle passage air amount d (m_thr) / dt per unit time of the equation (2), and the throttle inverse model is an inverse function of the compressor outlet pressure P2c of the equation (1). It is a function.

  As described above, the compressor outlet pressure P2c can be obtained from the intake pressure Pim detected by the intake pressure sensor 14. Therefore, the engine ECU 30 stores the inverse functions of the expressions (1) and (2), and calculates the compressor outlet pressure P2c by calculation using these inverse functions.

  Hereinafter, the flow of processing for calculating the shaft rotation speed will be described with reference to the flowchart of FIG. The shaft rotation speed calculation process is executed by the engine ECU 30 every predetermined cycle (for example, every 4 milliseconds). The shaft rotation speed calculation process basically conforms to the calculation block of FIG.

  First, in step S101, the intake pressure Pim detected by the intake pressure sensor 14 and the intake air temperature T detected by the intake air temperature sensor 15 are read, and the atmospheric pressure Patm detected by the atmospheric pressure sensor 16 is read. In step S102, an engine intake air amount d (m_e) / dt per unit time is calculated based on the engine rotation speed, the intake pressure Pim, and the previously stored charging efficiency.

  In step S103, based on the intake pressure Pim and the intake air temperature T read in step S101 and the engine intake air amount d (m_e) / dt calculated in step S102, the inverse function of equation (2) is used. Then, the throttle passage air amount d (m_thr) / dt per unit time is calculated. In step S104, the effective throttle area A_thr is calculated from the current opening of the throttle valve 13.

  In step S105, the engine intake air amount d (m_e) / dt per unit time and the throttle passage air amount d (m_thr) / dt per unit time, the intake pressure Pim and the intake air temperature T read in step S101, and Based on the above, the compressor outlet pressure P2c is calculated using the inverse function of equation (1).

  In step S106, a pressure ratio between the compressor inlet pressure P1c and the compressor outlet pressure P2c is calculated. Here, the atmospheric pressure Patm read in step S101 is set as the compressor inlet pressure P1c. In step S107, the shaft rotation speed is calculated based on the pressure ratio (P2c / P1c). In the present embodiment, the engine ECU 30 stores in advance a relationship between the pressure ratio and the shaft rotation speed as shown in FIG. 3 as a map, and calculates the shaft rotation speed using this map.

  FIG. 7 is a flowchart showing the flow of power assist control processing. The power assist control process is executed by the engine ECU 30 every predetermined period (for example, 4 milliseconds).

  First, in step S201, the target power of the turbocharger 20 is calculated based on the engine operating state, and in step S202, the actual power of the turbocharger 20 is calculated. In step S203, the assist power is calculated from the difference between the target power and the actual power.

  In step S204, the shaft rotation speed calculated in the shaft rotation speed calculation process in FIG. 6 is read.

  In step S205, a control signal including the assist power and the shaft rotation speed is output to the motor ECU 40. In this case, when the control signal is input, the motor ECU 40 calculates a necessary slip based on the shaft rotation speed and the assist power, and determines the frequency and voltage of the energization waveform reflecting the motor efficiency and the like. And according to the frequency and voltage, it supplies with electricity to each excitation coil of the stator 27 in order.

  As described above, according to the embodiment described in detail, the following excellent effects can be obtained.

  The shaft rotation speed is calculated based on the pressure ratio (P2c / P1c) between the compressor inlet pressure P1c and the compressor outlet pressure P2c. The inventor of the present application has confirmed that there is a correlation between the pressure ratio and the shaft rotation speed. By using the correlation, the shaft rotation speed can be obtained without depending on the rotation speed sensor.

  The induction motor 25 is driven based on the shaft rotation speed calculated from the correlation between the pressure ratio and the shaft rotation speed. Thereby, the induction motor 25 is appropriately driven based on the shaft rotation speed without depending on the rotation speed sensor.

  The compressor inlet pressure P1c was set to the atmospheric pressure Patm detected by the existing atmospheric pressure sensor 16. Thereby, it is not necessary to provide a new sensor for acquiring the compressor inlet pressure P1c. In this case, an air cleaner 17 is provided between the atmospheric pressure sensor 16 and the turbocharger 20. However, since the pressure loss due to the air cleaner 17 is small and can be almost ignored, an acquisition error of the compressor inlet pressure P1c is small.

  Further, a change in the flow rate and pressure of the intake air in the intake pipe 11 is modeled, and the compressor outlet pressure P2c is calculated from the intake pressure detected by the existing intake pressure sensor 14 using the model. Thereby, it is not necessary to provide a new sensor for acquiring the compressor outlet pressure P2c.

  According to the inventor of the present application, the shaft rotation speed is determined by the pressure ratio between the compressor inlet pressure P1c and the compressor outlet pressure P2c, and it is confirmed that the shaft rotation speed hardly depends on the change in the exhaust system or the warm-up state of the engine. ing. For this reason, it is possible to reduce the effort required for adaptation when creating a throttle model or an intake pipe model.

  In addition, this invention is not limited to embodiment described above, You may implement like (1)-(5) below.

  (1) In the above embodiment, the compressor outlet pressure P2c is calculated from the intake pressure Pim detected by the intake pressure sensor 14 using the inverse model of the throttle model and the intake pipe model. However, the present invention is not limited to this.

  A throttle map and an intake pipe map are defined as a multidimensional map corresponding to the throttle model and the intake pipe model. In this case, by using these maps, the compressor outlet pressure P2c and the intake pressure Pim downstream of the throttle valve 13 are associated with each other as in the calculation block shown in FIG. For this reason, the compressor outlet pressure P2c can be obtained from the intake pressure Pim detected by the intake pressure sensor 14 by performing the inverse calculation in the same manner as in the above embodiment. When the compressor outlet pressure P2c is calculated using such a multidimensional map, the calculation load by the engine ECU 30 is suppressed as compared with the case where the throttle model and the intake pipe model are used. Further, as described above, the shaft rotation speed is determined only by the pressure ratio between the compressor inlet pressure P1c and the compressor outlet pressure P2c, and is almost independent of changes in the exhaust system and the warm-up state of the engine. The amount of time required to specify

  In addition, a pressure sensor (supercharging pressure sensor) may be provided in the intake pipe 11 on the downstream side of the electric turbocharger 20, and the compressor outlet pressure P2c may be directly detected using the pressure sensor.

  (2) In the above embodiment, the atmospheric pressure Patm detected by the atmospheric pressure sensor 16 is used as the compressor inlet pressure P1c. However, the present invention is not limited to this. When the accuracy of the shaft rotation speed is not so required, a constant value such as standard atmospheric pressure (1013 hPa) may be used. In this case, even in an engine control system that does not include an atmospheric pressure sensor, the shaft rotation speed can be calculated.

  On the other hand, pressure loss due to the air cleaner 17 may be considered in order to obtain the shaft rotation speed with high accuracy. That is, the atmospheric pressure Patm detected by the atmospheric pressure sensor 16 may be corrected by the pressure loss by the air cleaner 17, and the correction result may be the compressor inlet pressure P1c.

  In addition, a pressure sensor may be provided in the intake pipe 11 on the upstream side of the electric turbocharger 20, and the compressor inlet pressure P1c may be directly detected using the pressure sensor.

  (3) The intake air supercharged by the electric turbocharger 20 expands as the temperature rises and the air density decreases, which causes a decrease in charging efficiency. For this reason, there is an engine control system provided with an intercooler for cooling the intake air. In this case, the cooling effect by the intercooler is obtained, but pressure loss occurs. Therefore, it is preferable to prepare an intercooler model that models such an intercooler, and calculate the compressor outlet temperature using the intercooler model in addition to the throttle model and the intake pipe model. Thereby, in the structure provided with the intercooler, it is possible to obtain the compressor outlet pressure P2c reflecting the cooling effect and pressure loss due to the intercooler.

  Of course, the cooling effect and pressure loss by the intercooler may be defined in advance as a map, and the compressor outlet pressure P2c may be calculated in combination with the throttle map and the intake pipe map.

  (4) In the above embodiment, in order to obtain the rotational speed of the shaft 23, the pressure ratio (P2c / P1c) between the compressor inlet pressure P1c and the compressor outlet pressure P2c is obtained, and the pre-defined pressure ratio and the shaft rotational speed are obtained. However, the present invention is not limited to this. A two-dimensional map associated with the shaft rotation speed using the compressor inlet pressure P1c and the compressor outlet pressure P2c as parameters may be defined in advance, and the two-dimensional map may be used. Also in this case, the shaft rotation speed is substantially associated with the pressure ratio between the compressor inlet pressure P1c and the compressor outlet pressure P2c.

  (5) In the above embodiment, the shaft rotation speed is calculated to drive the induction motor 25, but the present invention is not limited to this.

  If the turbocharger 20 breaks down, the rotation of the shaft 23 may be in an abnormal state (stationary or abnormal high-speed rotation, etc.). For this reason, you may use the shaft rotational speed calculated in order to determine whether abnormality has arisen in the turbocharger 20. FIG.

  Moreover, in the structure provided with the bypass path and the bypass valve (what is called a wastegate valve) which can open and close the bypass path so that the turbine wheel 22 may be bypassed, you may use as follows. In such a configuration, in order to avoid excessive supercharging by the turbocharger 20 as the exhaust power increases, the bypass valve is normally opened when the intake pressure detected by the intake pressure sensor 14 exceeds a predetermined value. The supercharging by the turbocharger 20 is suppressed by releasing the exhaust power. Here, since the supercharging effect by the turbocharger 20 also depends on the shaft rotation speed, the shaft rotation speed may be used as a condition for opening the bypass valve.

  In addition, it is conceivable that regenerative power generation is performed by the induction motor 25 when the exhaust power is excessive, such as during a high rotation speed range or during deceleration of the vehicle. At this time, since the maximum power that can be generated by the induction motor 25 is determined by the shaft rotation speed, the shaft rotation speed may be used when determining the target power generation amount.

It is a block diagram which shows the outline of the engine control system in embodiment of invention. It is a block diagram which shows the outline of an electric turbocharger. It is a figure which shows the relationship between a compressor pressure ratio and a shaft rotational speed. It is a calculation block diagram for calculating | requiring the intake pressure in the downstream of a throttle valve from a compressor outlet pressure. FIG. 5 is a calculation block diagram for obtaining a compressor outlet pressure from an intake pressure downstream of a throttle valve. It is a flowchart which shows a shaft rotational speed calculation process. It is a flowchart which shows a power assist control process.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Engine, 12 ... Throttle valve, 14 ... Intake pressure sensor, 17 ... Atmospheric pressure sensor, 20 ... Electric turbocharger, 25 ... Induction motor, 30 ... Engine ECU, 40 ... Motor ECU

Claims (6)

An internal combustion engine having a turbine wheel rotated by exhaust energy and a compressor impeller connected to the turbine wheel via a rotating shaft, and having a turbocharger that compresses intake air by the rotation of the compressor impeller and performs supercharging Applies to
Inlet pressure acquisition means for acquiring the inlet pressure of the compressor impeller;
Outlet pressure acquisition means for acquiring the outlet pressure of the compressor impeller;
Storage means for storing the rotational speed of the rotating shaft in association with the pressure ratio between the inlet pressure and the outlet pressure;
A rotational speed deriving means for deriving the rotational speed from the inlet pressure and the outlet pressure acquired by the two acquiring means and the correspondence stored in the storage means;
A control device for an internal combustion engine with a turbocharger, comprising:   The pressure sensor is applied to an internal combustion engine including an atmospheric pressure sensor capable of detecting atmospheric pressure, and the inlet pressure acquisition means uses the pressure detected by the atmospheric pressure sensor as an inlet pressure of the compressor impeller. A control device for an internal combustion engine with a turbocharger according to claim 1. An internal combustion engine having a turbine wheel rotated by exhaust energy and a compressor impeller connected to the turbine wheel via a rotating shaft, and having a turbocharger that compresses intake air by the rotation of the compressor impeller and performs supercharging Applies to
Outlet pressure acquisition means for acquiring the outlet pressure of the compressor impeller;
Storage means for storing the rotational speed of the rotary shaft in association with the outlet pressure;
A rotational speed deriving unit for deriving the rotational speed from the outlet pressure acquired by the outlet pressure acquiring unit and the correspondence stored in the storage unit;
A control device for an internal combustion engine with a turbocharger, comprising: Applied to an internal combustion engine having a turbocharger having an induction motor capable of assisting rotation of a rotation shaft of the turbocharger;
4. The turbocharged internal combustion engine according to claim 1, further comprising a control unit that controls the induction motor using a rotation speed of the rotation shaft calculated by the rotation speed acquisition unit. 5. Control device. Applied to an internal combustion engine having a throttle valve capable of adjusting the amount of intake air downstream of the compressor impeller in the intake passage of the internal combustion engine and an intake pressure sensor capable of detecting the pressure of intake air downstream of the throttle valve And
The outlet pressure acquisition means calculates the outlet pressure from the pressure of intake air downstream of the throttle valve detected by the intake pressure sensor, using a predetermined pressure change relationship in the intake passage. The control device for an internal combustion engine with a turbocharger according to any one of claims 1 to 4. The outlet pressure acquisition means
Means for calculating the flow rate of air passing through the throttle valve based on the pressure of the intake air downstream of the throttle valve detected by the intake pressure sensor, the intake air amount of the internal combustion engine, and the temperature of the intake air When,
Means for calculating the outlet pressure based on the flow rate of air passing through the throttle, the opening area of the throttle valve, the pressure of the intake air downstream of the throttle valve detected by the intake pressure sensor, and the temperature of the intake air;
The control apparatus for an internal combustion engine with a turbocharger according to claim 5, wherein

Images