JP2008045410A - Control device of internal combustion engine with supercharger - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To control a compressor in a high-efficiency operation area in the vicinity of a surge limit, while accurately avoiding a surge, in a control device of an internal combustion engine with a supercharger. <P>SOLUTION: The passing air amount of a centrifugal compressor 26a is acquired based on output of an air flowmeter 18. A surge limit compressor rotating speed is acquired based on the acquired compressor passing air amount. A compressor rotating speed (a turbo rotating speed) of a present state is acquired based on a turbo rotating speed sensor 30. A rotating speed of the compressor 26a is controlled based on the surge limit compressor rotating speed and the compressor rotating speed of the present state. More actually, a target compressor rotating speed is controlled so as to become a value based on an operation state of the internal combustion engine 10 such as accelerator opening and an engine speed, while being limited so as to become the surge limit compressor rotating speed or less. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a control device for an internal combustion engine with a supercharger.

  Conventionally, for example, Patent Document 1 discloses a control device for an internal combustion engine including a turbocharger. This conventional control device makes a surge judgment of the compressor of the turbocharger based on the relationship between the pressure ratio before and after the compressor and the flow rate of air passing through the compressor, or the relationship between the pressure ratio and the engine speed. ing.

JP 2001-342840 A Japanese Utility Model Publication No. 5-42642

    The intake pipe pressure of an internal combustion engine constantly fluctuates (pulsates). The above-described conventional technique using the pressure ratio before and after the compressor is affected by such pulsation of the intake system, and thus it takes time to calculate an accurate pressure ratio. Therefore, it is difficult to make a quick and accurate surge determination. On the other hand, in order to achieve efficient supercharging, it is desirable to control the compressor in the operating region near the surge limit. However, the above-described conventional method still leaves room for improvement in that the compressor is controlled in the operating region near the surge limit while the surge is accurately avoided.

  The present invention has been made to solve the above-described problems, and controls an internal combustion engine with a supercharger that can control a compressor in a highly efficient operation region near the surge limit while accurately avoiding a surge. An object is to provide an apparatus.

A first invention is a supercharger comprising a centrifugal compressor;
A rotational speed acquisition means for acquiring a compressor rotational speed of the centrifugal compressor;
Operating parameter acquisition means for acquiring the operating parameter of the internal combustion engine correlated with the operating characteristics of the centrifugal compressor and having less fluctuation than the intake pipe pressure;
Based on the operating parameters, limit rotational speed acquisition means for acquiring a surge limit compressor rotational speed,
Compressor control means for controlling the compressor speed based on the surge limit compressor speed and the compressor speed;
It is characterized by providing.

In a second aspect based on the first aspect, the compressor control means comprises:
Target rotational speed acquisition means for acquiring a target compressor rotational speed of the centrifugal compressor based on operating conditions of the internal combustion engine;
It further comprises target rotation speed limiting means for limiting the target compressor rotation speed to be equal to or less than the surge limit compressor rotation speed.

The third invention further comprises an electric motor for driving the centrifugal compressor in the second invention,
The compressor control means is provided separately from an engine control device that controls the operation of the internal combustion engine, and further includes a motor control device that controls the rotation speed of the electric motor,
The compressor control means includes the target rotation speed acquisition means and the target rotation speed limit means in an engine control device,
The motor control device controls the electric motor so that there is no difference between the target compressor rotation speed given from the engine control device and the current compressor rotation speed.

  According to a fourth aspect of the present invention, in any one of the first to third aspects, the operating parameter is an amount of air passing through the centrifugal compressor.

  According to a fifth aspect, in any one of the first to third aspects, the operating parameter is an engine speed.

  Further, a sixth invention is characterized in that, in the fifth invention, the limit rotational speed acquisition means acquires the surge limit compressor rotational speed based on the intake efficiency of the internal combustion engine in addition to the engine rotational speed. To do.

  According to the first aspect of the invention, the surge limit compressor rotation speed is acquired accurately and quickly based on the operation parameter with relatively little fluctuation. Then, based on the surge limit compressor rotation speed, the rotation speed of the compressor is controlled. For this reason, according to the present invention, it is possible to control the compressor in a high-efficiency operating region near the surge limit while accurately avoiding the surge.

  According to the second aspect of the present invention, the target compressor rotation speed is controlled so as to be equal to or less than the surge limit compressor rotation speed acquired accurately and quickly as described above, so that the compressor can be avoided while accurately avoiding the surge. Can be controlled in a highly efficient operating region near the surge limit.

  According to the third aspect of the invention, it is not necessary to separately provide a complicated feedback circuit or the like simply by giving the target compressor rotational speed from the engine control device to the electric motor whose rotational speed is controlled by the motor control device. As described above, according to the present invention, it is possible to realize supercharging control capable of avoiding surge with high accuracy while simplifying the configuration of the control system of the electric motor.

  According to the fourth aspect of the invention, the surge limit compressor rotation speed can be acquired accurately and quickly based on the compressor passing air amount.

  According to the fifth aspect, the surge limit compressor rotational speed can be acquired accurately and quickly based on the engine rotational speed.

  According to the sixth aspect of the invention, in the internal combustion engine with a supercharger including an actuator that affects the intake efficiency, the change in the intake efficiency accompanying the drive of the actuator can be reflected in the surge limit compressor rotational speed. Therefore, according to the present invention, when the internal combustion engine is provided with such an actuator, the compressor can be operated with high efficiency near the surge limit while avoiding the surge with higher accuracy than the fifth invention. It becomes possible to control with.

Embodiment 1 FIG.
[Description of system configuration]
FIG. 1 is a schematic configuration diagram for explaining the configuration of the first embodiment of the present invention. As shown in FIG. 1, the system of the present embodiment includes an internal combustion engine 10. The intake system of the internal combustion engine 10 includes an intake manifold 12 and an intake pipe (intake passage) 14 connected to the intake manifold 12. Air is taken into the intake pipe 14 from the atmosphere and distributed to the combustion chambers of the respective cylinders via the intake manifold 12.

  An air cleaner 16 is attached to the inlet of the intake pipe 14. An air flow meter 18 that outputs a signal corresponding to the flow rate of air sucked into the intake pipe 14 is provided in the vicinity of the downstream side of the air cleaner 16. A throttle valve 20 is provided upstream of the intake manifold 12. An intercooler 22 that cools the compressed air is provided upstream of the throttle valve 20. A supercharging pressure sensor 24 that outputs a signal corresponding to the pressure in the intake pipe 14 is disposed downstream of the intercooler 22.

  A turbocharger with an electric motor (motor-assisted turbocharger, hereinafter referred to as MAT) 26 is provided in the middle of the intake pipe 14 from the air flow meter 18 to the throttle valve 20. The MAT 26 includes a centrifugal compressor 26a, a turbine 26b, and an electric motor 28 disposed between the compressor 26a and the turbine 26b. Here, it is assumed that an AC motor is used as the electric motor 28. The compressor 26a and the turbine 26b are integrally connected by a connecting shaft, and the compressor 26a is rotationally driven by the exhaust energy of the exhaust gas input to the turbine 26b. The connecting shaft is also a rotor of the electric motor 28, and the compressor 26a can be forcibly driven by operating the electric motor 28. Further, a turbo rotational speed sensor 30 that outputs a signal corresponding to the rotational speed of the compressor 26a (= turbo rotational speed = motor rotational speed) is attached to the connecting shaft. Note that the turbo rotation speed in the MAT 26 is the same as the motor rotation speed of the electric motor 28, so that it may be detected based on the current supplied to the electric motor 28 without using the turbo rotation speed sensor 30. .

  One end of an intake bypass pipe 32 is connected in the middle of the intake pipe 14 from the compressor 26 a to the intercooler 22. The other end of the intake bypass pipe 32 is connected to the upstream side of the compressor 26a. A bypass valve 34 for controlling the flow rate of the air flowing through the intake bypass pipe 32 is disposed in the intake bypass pipe 32. By operating the bypass valve 34 and opening the inlet of the intake bypass pipe 32, a part of the air compressed by the compressor 26a is returned again to the inlet side of the compressor 26a. When the turbocharger 26 is in an operating state in which a surge is likely to occur, the surge can be prevented by returning a part of the air exiting the compressor 26 a to the inlet side of the compressor 26 a through the intake bypass pipe 32.

  An intake pressure sensor 36 that outputs a signal corresponding to the pressure in the intake pipe 14 and an intake air temperature sensor 37 that outputs a signal corresponding to the inlet air temperature of the compressor 26a are disposed upstream of the compressor 26a.

  The exhaust system of the internal combustion engine 10 includes an exhaust manifold 38 and an exhaust pipe 40 connected to the exhaust manifold 38. Exhaust gas discharged from each cylinder of the internal combustion engine 10 is collected in the exhaust manifold 38 and discharged to the exhaust pipe 40 through the exhaust manifold 38.

  The exhaust pipe 40 is connected to an exhaust bypass passage 42 that bypasses the turbine 26b and connects the inlet side and the outlet side of the turbine 26b. An electric waste gate valve 44 is disposed in the middle of the exhaust bypass passage 42. The wastegate valve 44 is opened and closed based on the supercharging pressure of the intake air detected by the supercharging pressure sensor 24. The waste gate valve is not limited to an electric type, and may be a pressure regulating type valve that utilizes a pressure difference.

  Further, the system shown in FIG. 1 includes an intake variable valve mechanism 46 and an exhaust variable valve mechanism 48 for driving the intake valve and the exhaust valve of each cylinder, respectively. These variable valve mechanisms 46 and 48 are assumed to include a VVT mechanism for controlling the opening / closing timing of the intake valve and the exhaust valve.

  The control system of the internal combustion engine 10 includes an ECU (Electronic Control Unit) 50 and a motor controller 52. The maximum rotational speed of the internal combustion engine 10 is approximately 6,000 revolutions per minute, whereas the maximum rotational speed of the turbocharger 26 is approximately 200,000 revolutions per minute and is very high speed. For this reason, the motor controller 52 requires high-speed processing as compared with other engine controls. Therefore, it is provided separately from the engine ECU 50. The motor controller 52 controls the energization state to the electric motor 28 based on the number of revolutions based on a command from the ECU 50. Electric power to the electric motor 28 is supplied from the battery 54. The ECU 50 is a control device that comprehensively controls the entire system shown in FIG.

  On the output side of the ECU 50, in addition to the motor controller 52, in addition to actuators such as the throttle valve 20 and the bypass valve 34, a fuel injection valve 56 for supplying fuel to each cylinder is connected. Further, on the input side of the ECU 50, in addition to the air flow meter 18 and the supercharging pressure sensor 24, a crank angle sensor 58 for detecting the engine speed NE, an accelerator position sensor 60 for detecting the accelerator opening degree, and the like. Various sensors are connected. The turbo controller 30 is connected to the motor controller 52. In addition to these devices and sensors, a plurality of devices and sensors are connected to the ECU 50, but the description thereof is omitted here. The ECU 50 drives each device according to a predetermined control program based on the output of each sensor.

[Control system of electric motor of this embodiment]
FIG. 2 is a block diagram for explaining a control system of the electric motor 28 provided in the MAT 26. As shown in FIG. 2, the electric motor 28 that is an AC motor is driven based on commands from the engine ECU 50 and the motor controller 52. In the engine ECU 50, the target turbo speed of the electric motor 28 is calculated in accordance with parameters that are operating conditions of the internal combustion engine 10, such as the accelerator opening and the engine speed. Basically, the target turbo rotational speed calculated here is output from the engine ECU 50 to the motor controller 52. In the motor controller 52, the motor control rotational speed is calculated so that the deviation between the target turbo rotational speed and the current turbo rotational speed detected by the turbo rotational speed sensor 30 approaches zero. The motor current applied to the electric motor 28 is controlled so as to achieve the rotation speed.

  Further, the engine ECU 50 of the present embodiment calculates the surge limit turbo rotation speed (surge limit compressor rotation speed) in relation to the compressor passing air amount in accordance with a surge map described later with reference to FIGS. 3 and 4. Then, as shown in FIG. 2, the engine ECU 50 sets the smaller one of the surge limit turbo speed and the target turbo speed to the motor controller 52 as the final target turbo speed. I am trying to output.

  When the relationship between the engine ECU 50 and the motor controller 52 described above is organized, the engine ECU 50 calculates the target turbo rotation speed to be given to the electric motor 28 and issues a command to the motor controller 52 for the target turbo rotation speed. Then, the motor controller 52 gives the electric motor 28 by the turbo speed feedback control using the PID control based on the target turbo speed (including the surge limit turbo speed) received from the engine ECU 50. Control of the motor current is performed.

[Control method of electric motor (AC motor) of this embodiment]
FIG. 3 is a diagram showing the relationship between the pressure ratio of the outlet pressure to the inlet pressure of the compressor 26a and the amount of air passing through the compressor. A curve indicated by a bold line in FIG. 3 represents a surge line. In FIG. 3, a hatched region on the left side of the surge line corresponds to the surge region. That is, the surge is likely to occur under a situation where the pressure ratio of the compressor 26a is large and the amount of air passing through the compressor is small.

  FIG. 3 shows an equal turbo rotation speed line. As shown in FIG. 3, when the turbo rotational speed is constant, the surge region approaches the smaller the amount of air passing through the compressor. Further, there is a relationship between the turbo rotation speed and the pressure ratio that the higher the pressure ratio, the higher the turbo rotation speed. According to the relationship shown in FIG. 3, if the amount of air passing through the compressor, which is one of the operating parameters of the internal combustion engine 10, is known, the turbo rotation speed reaching the surge line, that is, the surge limit turbo rotation speed can be grasped. Can do.

  FIG. 4 is a diagram directly representing the relationship between the amount of air passing through the compressor and the surge limit turbo rotational speed. As shown in FIG. 4, the surge limit turbo rotational speed tends to increase as the amount of air passing through the compressor increases. If the relationship shown in FIG. 4 is stored in the ECU 50 as a surge map, the surge limit turbo rotational speed can be acquired by acquiring the compressor passing air amount measured by the air flow meter 18.

  In order to achieve efficient supercharging, it is desirable to control the compressor 26a near the surge line. Therefore, in the present embodiment, the electric motor 28 of the MAT 26 is controlled based on the surge limit turbo rotational speed calculated based on the surge map shown in FIG. 4 and the current turbo rotational speed. More specifically, the target turbo rotational speed of the electric motor 28 is controlled within a range not exceeding the surge limit turbo rotational speed calculated as described above.

[Specific Processing in Embodiment 1]
FIG. 5 is a flowchart of a routine executed by the ECU 50 in the first embodiment to realize the above function. In the routine shown in FIG. 5, first, the current accelerator opening and the engine speed are acquired based on the outputs of the accelerator position sensor 60 and the crank angle sensor 58, and based on these, the target turbo rotation of the electric motor 28 is acquired. A number is calculated (step 100).

  Next, the amount of air passing through the compressor is measured by the air flow meter 18 (step 102), and then the turbo speed is measured by the turbo speed sensor 30 (step 104).

  Next, the surge limit turbo rotational speed is calculated based on the surge map and the compressor passing air amount acquired in step 102 (step 106). The ECU 50 stores the relationship shown in FIG. 4 as a surge map for acquiring the surge limit turbo rotational speed. Such a surge map is determined in advance by experiments or the like.

  Next, it is determined whether or not the surge limit turbo rotational speed acquired in step 106 is larger than the target turbo rotational speed calculated in step 100 (step 108). As a result, when the surge limit turbo rotational speed> the target turbo rotational speed is satisfied, it can be determined that the current target turbo rotational speed has not yet reached the surge limit. For this reason, the target turbo rotational speed calculated in step 100 is used as it is.

  On the other hand, if it is determined in step 108 that the surge limit turbo rotation speed> the target turbo rotation speed is not satisfied, the target turbo rotation speed is set so as to prevent the operating point of the compressor 26a from entering the surge region. Is replaced with the surge limit turbo rotational speed calculated in step 106 from the value calculated in step 100 (step 110).

  According to the routine shown in FIG. 5 described above, the surge limit turbo rotation speed is acquired accurately and quickly based on the compressor passing air amount, and the target turbo rotation speed of the electric motor 28 does not exceed the surge limit turbo rotation speed. It will be controlled within the range. Then, as described with reference to the block diagram shown in FIG. 2, the turbo that uses the current turbo speed so that the motor controller 52 can achieve the target turbo speed that is suppressed within the surge limit. The rotational speed of the motor, that is, the turbo rotational speed is controlled by feedback control of the rotational speed. For this reason, according to the method of the present embodiment, it is possible to control the compressor 26a in a highly efficient operation region near the surge limit while avoiding the surge with high accuracy.

  Unlike the method of the present embodiment described above, a method of controlling the electric motor 28 based on the boost pressure is also known. More specifically, the engine ECU calculates a pressure ratio that becomes a surge limit from the relationship between the compressor passing air amount and the turbo rotation speed, and calculates the limit pressure of the supercharging pressure from the surge limit pressure ratio. Next, a target value of the motor output of the electric motor is calculated based on the difference between the limit pressure and the current supercharging pressure. Next, the target value of the motor output calculated by the engine ECU is output to the motor controller. The motor controller determines a predetermined target turbo rotational speed (motor rotational speed) so that the difference between the target value of the motor output and the current motor output value approaches zero. Then, the motor current is controlled so that the difference between the target turbo speed and the current turbo speed becomes zero.

When the pressure ratio is used as a parameter as in the conventional method as described above, since the intake pipe pressure is affected by the pulsation of the intake system, an accurate pressure ratio is based on the intake pipe pressure having a large fluctuation. It takes a certain time (several hundred milliseconds) to calculate. As described above, when the supercharging pressure is used, a delay in control and a variation in measurement values are large, and it is difficult to make a surge determination quickly and accurately. As a result, in order to reliably avoid the surge, it is necessary to operate the turbocharger with a predetermined margin for the surge line. If such a margin for the surge is provided, efficient supercharging cannot be realized in the vicinity of the surge line.
If the conventional method is used, a boost pressure feedback circuit is required in the engine ECU. In spite of the fact that the rotational speed of the AC motor is controlled, it is necessary to add a feedback circuit for the motor output in the motor controller in addition to the feedback circuit for the turbo rotational speed.

  On the other hand, in the method of the present embodiment, which is based on control of the turbo rotation speed (motor rotation speed), the parameters that need to be measured in real time are the compressor passing air amount and the turbo rotation speed. Since the amount of air passing through the compressor is measured in the vicinity of the inlet of the intake pipe 14 that is hardly affected by pulsation, an accurate value can be obtained in a relatively short time. Then, as shown in the processing of steps 108 to 110, a target turbo rotational speed that considers the surge limit is given to the motor controller 52 that attempts to control the rotational speed of the electric motor 28 that is an AC motor. Therefore, it is not necessary to provide the control system for the electric motor 28 with a feedback circuit for the supercharging pressure and the motor output as the conventional method has. Therefore, according to the method of the present embodiment, it is possible to realize supercharging control that can avoid a surge with high accuracy while simplifying the configuration of the control system of the electric motor 28.

  By the way, in Embodiment 1 mentioned above, in order to avoid a surge, the compressor passing air amount measured by the air flow meter 18 and the current turbo rotational speed measured by the turbo rotational speed sensor 30 are directly used. I have to. However, in order to more reliably avoid the surge, the target turbo speed may be controlled by a method described with reference to FIGS. 6 and 7 below.

FIG. 6 is a flowchart of a routine executed by the ECU 50 in order to realize such a modified example of the target turbo rotational speed control. In FIG. 6, the same steps as those shown in FIG. 5 are denoted by the same reference numerals, and the description thereof is omitted or simplified.
In the routine shown in FIG. 6, first, the intake air temperature and the intake air pressure are measured based on the outputs of the intake air temperature sensor 37 and the intake air pressure sensor 36, respectively (step 200).

Next, after the compressor passing air amount and the turbo rotational speed are measured (steps 102 and 104), the compressor passing air amount and the turbo rotational speed obtained in steps 102 and 104 are calculated based on the intake air temperature and the intake pressure. Each is corrected (step 202). Specifically, it is corrected according to the following equation.
Corrected air volume = Compressor air volume x √θ / δ
Modified turbo speed = turbo speed / √θ
In the above equations, θ is the intake air temperature / reference temperature (for example, 293.15K), and δ is the intake air pressure / reference pressure (for example, 101.325 kPa abs (absolute pressure)).

  Next, the surge limit turbo rotation speed is calculated based on the surge map shown in FIG. 7 and the corrected air amount acquired in step 202 (step 204). FIG. 7 is a surge map stored in the ECU 50 in order to acquire the surge limit turbo rotational speed based on the corrected air amount. The map shown in FIG. 7 is the same as the map shown in FIG. 4 described above except that the compressor passing air amount is changed to the corrected air amount.

  Next, a comparison is made between the surge limit turbo rotational speed acquired in step 204 and the corrected turbo rotational speed acquired in step 202 (step 206). As a result, when it is determined that the surge limit turbo rotation speed> the corrected turbo rotation speed is established, it can be determined that the current target turbo rotation speed has not yet reached the surge limit. Therefore, in this case, the corrected turbo speed is used as the target turbo speed (step 208).

  On the other hand, if it is determined in step 206 that the surge limit turbo rotation speed> the corrected turbo rotation speed is not established, the surge limit turbo rotation is performed in order to prevent the operating point of the compressor 26a from entering the surge region. The number is used as the target turbo speed (step 110).

  According to the routine shown in FIG. 6 described above, the calculation accuracy of the surge limit turbo rotational speed can be further improved as compared with the method shown in FIG. 5, so that surge can be avoided with higher accuracy. However, the compressor 26a can be controlled in a highly efficient operating region near the surge limit.

In the first embodiment described above, the ECU 50 executes the process in step 104, so that the “rotation speed acquisition means” in the first invention executes the process in step 102. The “operating parameter acquisition means” in the first aspect of the invention executes the processing of step 106, and the “limit rotational speed acquisition means” in the first aspect of the invention executes the processing of steps 108 and 110. The “compressor control means” in the first invention is realized.
Further, when the ECU 50 executes the process of step 100, the “target rotational speed acquisition means” in the second invention executes the process of step 110 when the determination of step 108 is not established. The “target rotation speed limiting means” in the second aspect of the present invention is realized.
The engine ECU 50 corresponds to the “engine control device” in the third invention, and the motor controller 52 corresponds to the “motor control device” in the third invention.

Embodiment 2. FIG.
Next, a second embodiment of the present invention will be described with reference to FIG.
The system of the present embodiment can be realized by causing the ECU 50 to execute a routine similar to the routine shown in FIG. 5 using the hardware configuration shown in FIG.

[Features of Embodiment 2]
FIG. 8 is a diagram showing a surge map used in the second embodiment. In the first embodiment described above, the surge limit turbo rotational speed is calculated according to a surge map defined in relation to the amount of air passing through the compressor. However, the operating parameters of the internal combustion engine 10 that can be used for surge determination, which are correlated with the operating characteristics of the compressor 26a and less fluctuated compared to the intake pipe pressure, are the compressor passing air. It is not limited to the amount. For example, the engine speed may be used. In other words, as shown in FIG. 8, the present embodiment is characterized in that the surge limit turbo rotational speed is calculated according to a surge map determined in relation to the engine rotational speed.

  There is a correlation as shown in the compressor map of FIG. 3 among the engine speed, the turbo speed, and the surge region. Therefore, if the engine speed is known in the same way as the case of the compressor passing air amount, the turbo speed reaching the surge line, that is, the surge limit turbo speed can be grasped.

  The target turbo speed control using the surge map that defines the surge limit turbo speed in relation to the engine speed is a similar routine in which the compressor passing air amount in the routine shown in FIG. 5 is replaced with the engine speed. Can be realized by causing the ECU 50 to execute the same, and the same effects as those of the first embodiment described above can be obtained.

Embodiment 3 FIG.
Next, a third embodiment of the present invention will be described with reference to FIG.
The system of the present embodiment can be realized by causing the ECU 50 to execute a routine similar to the routine shown in FIG. 5 using the hardware configuration shown in FIG.

[Features of Embodiment 3]
FIG. 9 is a diagram showing a surge map used in the third embodiment. The surge map of the present embodiment defines the surge limit turbo rotational speed in relation to the engine rotational speed as in the second embodiment described above. Incidentally, the intake efficiency of the internal combustion engine 10 changes, for example, when the opening of the swirl control valve changes or when the control positions of the variable valve mechanisms 46, 48 change. Therefore, the present embodiment is characterized in that a change in intake efficiency due to driving of an actuator provided in such an internal combustion engine 10 is reflected in a surge map.

  To explain conceptually, as shown in FIG. 9, the surge map of this embodiment includes a plurality of surge lines in the surge map corresponding to the control amount of the actuator of the internal combustion engine 10 (here, the opening of the swirl control valve). It has a book. This surge line is set such that the value of the surge limit turbo speed for a certain engine speed increases as the opening of the swirl control valve increases, that is, as the intake efficiency increases.

  According to the surge map of the present embodiment described above, the surge limit turbo rotational speed is calculated based on the opening degree of the swirl control valve in addition to the engine rotational speed. For this reason, the change of the intake efficiency accompanying the drive of the actuator of the internal combustion engine 10 can be reflected in the calculation of the surge limit turbo rotational speed. Then, by using the surge limit turbo rotational speed calculated as described above, the compressor 26a can be operated in a highly efficient operating range near the surge limit while avoiding the surge more accurately than in the second embodiment. It becomes possible to control with.

By the way, in the third embodiment described above, the surge limit turbo rotational speed is calculated based on the opening degree of the swirl control valve which is an actuator related to the intake efficiency of the internal combustion engine 10. The actuator related to the intake efficiency of 10 may be the valve opening characteristics (lift amount, working angle, opening / closing timing, etc.) of the intake / exhaust valves controlled by the variable valve mechanisms 46, 48.
Furthermore, as another method for considering the intake efficiency, an intake manifold pressure sensor and an intake manifold intake temperature sensor for detecting the pressure and temperature in the intake manifold 12 of the internal combustion engine 10 may be provided. Then, the intake efficiency may be calculated during operation of the internal combustion engine 10 according to the following equation, and the surge line in the surge map may be changed according to the calculated intake efficiency.
Intake efficiency (volumetric efficiency) = (intake air volume / intake air density) / (engine speed x displacement) x (reference pressure / intake manifold pressure) x (intake manifold intake temperature / reference temperature)

  In the first to third embodiments described above, the turbocharger 26 including the electric motor 28 capable of forcibly driving the compressor 26a is used. However, the turbocharger in the present invention is a centrifugal compressor. If it is provided, it is not limited to this. That is, for example, an electric compressor may be used.

It is a schematic block diagram for demonstrating the structure of Embodiment 1 of this invention. It is a block diagram for demonstrating the control system of the electric motor with which the turbocharger of Embodiment 1 of this invention is provided. It is a figure which shows the relationship between the pressure ratio of the outlet pressure with respect to the inlet pressure of a compressor, and the compressor passage air amount. It is the figure which expressed directly the relation between the amount of air passing through the compressor and the surge limit turbo rotation speed. It is a flowchart of the routine performed in Embodiment 1 of the present invention. It is a flowchart of the routine performed in the modification of Embodiment 1 of this invention. It is a surge map for acquiring the surge limit turbo rotation speed based on the corrected air amount. It is a figure showing the surge map used in Embodiment 2 of this invention. It is a figure showing the surge map used in Embodiment 3 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Internal combustion engine 14 Intake pipe 18 Air flow meter 24 Supercharging pressure sensor 26 Turbocharger 26a with electric motor Compressor 26b Turbine 28 Electric motor 30 Turbo rotation speed sensor 36 Intake pressure sensor 37 Intake temperature sensor 40 Exhaust pipe 46 Intake variable valve Mechanism 48 Exhaust variable valve mechanism 50 ECU (Electronic Control Unit)
52 motor controller 56 fuel injection valve 58 crank angle sensor 60 accelerator position sensor

Claims (6)

A turbocharger comprising a centrifugal compressor;
A rotational speed acquisition means for acquiring a compressor rotational speed of the centrifugal compressor;
Operating parameter acquisition means for acquiring the operating parameter of the internal combustion engine correlated with the operating characteristics of the centrifugal compressor and having less fluctuation than the intake pipe pressure;
Based on the operating parameters, limit rotational speed acquisition means for acquiring a surge limit compressor rotational speed,
Compressor control means for controlling the compressor speed based on the surge limit compressor speed and the compressor speed;
A control device for an internal combustion engine with a supercharger. The compressor control means includes
Target rotational speed acquisition means for acquiring a target compressor rotational speed of the centrifugal compressor based on operating conditions of the internal combustion engine;
The control apparatus for an internal combustion engine with a supercharger according to claim 1, further comprising target speed limiting means for limiting the target compressor speed so as to be equal to or less than the surge limit compressor speed. An electric motor for driving the centrifugal compressor;
The compressor control means is provided separately from an engine control device that controls the operation of the internal combustion engine, and further includes a motor control device that controls the rotation speed of the electric motor,
The compressor control means includes the target rotation speed acquisition means and the target rotation speed limit means in an engine control device,
The said motor control apparatus controls the said electric motor so that the difference of the said target compressor rotation speed given from the said engine control apparatus and the said present compressor rotation speed may be eliminated. Control device for an internal combustion engine with a feeder.   The control device for an internal combustion engine with a supercharger according to any one of claims 1 to 3, wherein the operating parameter is an amount of air passing through the centrifugal compressor.   The control device for an internal combustion engine with a supercharger according to any one of claims 1 to 3, wherein the operating parameter is an engine speed.   6. The control of an internal combustion engine with a supercharger according to claim 5, wherein the limit rotation speed acquisition means acquires the surge limit compressor rotation speed based on an intake efficiency of the internal combustion engine in addition to the engine rotation speed. apparatus.

Images