JP2019183744A - Control device of internal combustion engine with supercharger - Google Patents

Abstract

To provide a control device of an internal combustion engine with a supercharger improved to properly adjust a turbo rotation speed as a turbo noise countermeasure.SOLUTION: A control in a step S104 is operated when results of determinations in both of first determination in a step S100 and second determination in a step S102 are positive (YES). In the step S104, different countermeasures are taken between deceleration and acceleration. During the deceleration, a waste gate valve or a variable nozzle is set to an opening side with respect to that in a normal time. Thus a turbo rotation speed is lowered, so that the turbo rotation speed is deviated from a prescribed turbo rotation speed range as early as possible. On the other hand, during the acceleration, the waste gate valve or the variable nozzle are set to a closing side with respect to that in the normal time. Thus the turbo rotation speed is increased, so that the turbo rotation speed is deviated from the prescribed turbo rotation speed range as early as possible.SELECTED DRAWING: Figure 1

Description

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

  2. Description of the Related Art Conventionally, as disclosed in, for example, Japanese Patent Application Laid-Open No. 2010-270640, there is known an internal combustion engine that is improved so as to suppress turbo noise when the engine rotation speed is reduced in principle in a supercharger. . In this prior art, control is constructed so as to reduce the turbo rotation speed when the engine rotation speed becomes a predetermined value or less.

JP 2010-270640 A JP 2011-157881 A JP 2008-150013 A

  There is a frequency range in which the turbo sound increases according to the turbo rotation speed. The factors of this frequency range are the frequency characteristics of the force generated by the turbocharger and the frequency characteristics of the body and exhaust system parts. The conventional control does not take into consideration that there is a range in which the turbo sound increases. Therefore, when the turbo rotational speed is within the specific range at the time of acceleration or deceleration, there is a problem that the turbo sound is transmitted as an abnormal sound to the vehicle occupant.

  The present invention has been made to solve the above-described problems, and provides a control device for an internal combustion engine with a supercharger that is improved so as to appropriately execute turbo rotation speed adjustment as a measure against turbo noise. The purpose is to do.

A control device for an internal combustion engine with a supercharger according to the present invention comprises:
Obtaining means for obtaining a turbo rotation speed of a turbocharger that supercharges intake air of the internal combustion engine;
Determining means for determining whether or not the turbo rotation speed is within a predetermined turbo rotation speed range;
When the turbo rotational speed is within the predetermined turbo rotational speed range, the engine rotational speed of the internal combustion engine decreases so that the turbo rotational speed decreases during deceleration where the engine rotational speed of the internal combustion engine decreases. Adjusting means for adjusting the turbo rotational speed of the turbocharger so that the turbo rotational speed increases during the ascending acceleration;
Is provided.

  According to the present invention, when the turbo rotation speed is within the predetermined turbo rotation speed range, the turbo rotation speed can be adjusted so that the rotation speed can be quickly exited. The predetermined turbo rotation speed range is set with a specific turbo rotation speed range in which the turbo sound increases based on the frequency characteristics of the force generated by the turbocharger and the frequency characteristics of the body and exhaust system parts. This suppresses the transmission of turbo sound to the occupant during acceleration or deceleration, while maintaining the highest possible rotational speed even when it is necessary to reduce the turbo rotational speed in consideration of NV. it can.

It is a control flowchart performed in the control apparatus of the supercharger-equipped internal combustion engine according to the embodiment. It is a figure for demonstrating the setting of the turbo rotational speed abnormal range in the control apparatus of the internal combustion engine with a supercharger concerning embodiment. It is a figure for demonstrating the setting method of the turbo rotational speed abnormal range in the control apparatus of the internal combustion engine with a supercharger concerning embodiment. It is a figure for demonstrating the setting method of the turbo rotational speed abnormal range in the control apparatus of the internal combustion engine with a supercharger concerning embodiment. It is a figure for demonstrating the setting method of the background noise abnormal range in the control apparatus of the internal combustion engine with a supercharger concerning embodiment. It is a figure for demonstrating the setting method of the background noise abnormal range in the control apparatus of the internal combustion engine with a supercharger concerning embodiment. It is a control flowchart performed in the control apparatus of the internal combustion engine with a supercharger concerning the modification of embodiment.

  According to the embodiment, there is provided control that is constructed so as to avoid the sound generated by the turbocharger even a little. The sound generated due to the turbocharger is a sound of a primary rotation component generated by rotational imbalance or a sound generated by a so-called whirl that is self-excited vibration of the shaft. It is constructed so that the turbo rotation range in which the turbo sound determined from the balance with the frequency characteristics of the force generated by the turbocharger, the natural frequency characteristics of the related parts, and the background noise is large can be escaped as soon as possible.

  An internal combustion engine with a supercharger according to an embodiment includes a turbocharger that supplies intake air of the internal combustion engine, a turbo rotation speed acquisition unit that acquires the rotation speed of the turbocharger, an engine rotation speed sensor, an air flow meter, and the like Engine load control unit, vehicle speed sensor, waste gate valve (WGV) or variable nozzle (VN), EGR valve, engine sensor unit connected to these sensor devices and actuators And. The turbo rotation speed acquisition means may acquire a monitor value using a turbo rotation speed sensor, or may execute calculation processing for predicting the turbo rotation speed by the engine electronic control unit. The variable nozzle can change the turbocharging efficiency of the turbocharger according to the opening.

  FIG. 1 is a control flowchart executed in the control device for the supercharged internal combustion engine according to the embodiment. The routine shown in FIG. 1 is executed by the engine electronic control unit.

  In the routine of FIG. 1, first, the first determination relating to step S100 is performed. The process of step S100 corresponds to a determination unit that determines whether or not the turbo rotation speed is within a predetermined turbo rotation speed range. First, the engine electronic control unit acquires the turbo rotation speed, and the acquisition is realized by a monitor value by a sensor or a prediction processing calculation. It is determined whether or not the current turbo rotation speed falls within a “predetermined turbo rotation speed range” set as a range in which turbo sound is not possible.

  The “predetermined turbo rotational speed range” is a specific turbo rotational speed range in which the turbo sound becomes louder based on the frequency characteristics of the force generated by the turbocharger and the frequency characteristics of the body and exhaust system parts. The predetermined turbo rotation speed range is set in advance in consideration of the hardware characteristics. Here, the hard characteristics may include a frequency characteristic of turbo forcing including a primary rotation component and a whirl component, a frequency characteristic of exhaust system parts, and a transmission characteristic of a vehicle body.

  2-4 is a figure for demonstrating the setting method of the turbo rotational speed abnormal range in the control apparatus of the internal combustion engine with a supercharger concerning embodiment. 2 to 4 are diagrams for explaining a method of presetting a predetermined turbo rotation speed range. FIG. 2 shows a graph of the turbo rotation speed and frequency, and shows the relationship between the turbo rotation speed and the primary rotation component and the whirl component. The whirl component is represented in the range surrounded by the symbol P1 in FIG. The whirl component is the vibration around the rotating body (self-excited vibration) due to the bearing oil film. The rotation primary component is represented in the range surrounded by the symbol P2 in FIG. The rotating primary component is a centrifugal force due to the rotating body imbalance. FIG. 3 shows an example of the frequency characteristic of the exhaust system. FIG. 4 shows an example of the frequency characteristic of the vehicle. A predetermined turbo rotation speed range is set in advance in consideration of the balance with these characteristics.

  When the determination result of step S100 is affirmative (YES), the second determination related to step S102 is performed. In step S102, first, the engine electronic control unit obtains the engine rotation speed, torque, and vehicle speed from various sensor devices, whereby the current operating conditions are specified. It is determined whether or not the current operating condition corresponds to a “predetermined operating condition range” set as a range in which the background noise level is not possible. The predetermined operating condition range is set in advance in consideration of the operating condition and the background noise level. The driving conditions may be set in consideration of the relationship between the engine speed, the engine load (torque), and the radiated sound or in-vehicle sound, and set in consideration of the relationship between the vehicle speed and the in-vehicle sound. Also good.

  5 and 6 are diagrams for explaining a background noise abnormal range setting method in the control device for a supercharger-equipped internal combustion engine according to the embodiment. 5 and 6 are diagrams for explaining a method of presetting a predetermined operating condition range in which the background noise level is impossible. FIG. 5 schematically shows the relationship between the vehicle speed and the background noise in the vehicle. FIG. 6 schematically shows the relationship between the engine rotational speed, torque, and engine radiation sound. The predetermined operating condition range is set in advance in consideration of the balance with these characteristics.

  Next, the control content concerning step S104 is demonstrated. When the determination results of both the first determination and the second determination are affirmative (YES), the control in step S104 is activated. In step S104, different actions are taken during deceleration and acceleration. First, during deceleration, the wastegate valve or the variable nozzle is set to the open side relative to the normal time. As a result, the turbo rotation speed is decreased so that the turbo rotation speed is out of the predetermined turbo rotation speed range as early as possible. On the other hand, during acceleration, the wastegate valve or variable nozzle is set closer to the closed side than normal. Thus, the turbo rotation speed is increased so that the turbo rotation speed is out of the predetermined turbo rotation speed range as early as possible. Thereafter, the current routine ends.

  Note that the processing in step S104 corresponds to “adjustment means” described in the means for solving the above-described problem.

  The effects according to the embodiment will be described. The turbo abnormal noise phenomenon is generated from a primary rotational force caused by unbalanced turbo rotors and a whirl force caused by self-excited vibration of the shaft generated in the turbo bearing clearance (oil film). These events are related to the generated turbo rotation speed and the generated forced force frequency characteristics, and differ depending on the specifications of the turbocharger. The forcing force is transmitted as sound or vibration from the exhaust system parts to the vehicle parts, and the problematic sound reaches the inside of the vehicle. If the frequency characteristics of the forcing force generated by the turbo and the frequency characteristics of the exhaust system parts and the vehicle parts that serve as transmission paths match, the problematic noise will increase. When such a loud sound is generated in a situation where the background noise level is low, there is a problem such as uncomfortableness.

  In this regard, according to the embodiment, the control logic shown in FIG. 1 determines whether or not the turbo sound is loud enough to cause a problem, and determines whether or not the driving environment is conspicuous. This is determined in S102. According to the embodiment, when the determination result is affirmative (YES) in both step S100 and step S102, the turbo rotation speed can be deviated from the unusable range as early as possible. Therefore, the turbo sound generation time can be shortened and sensory discomfort can be reduced.

  A supplementary description will be given of the prior art. In a supercharger with an electric motor, there is a conventional technique that suppresses turbo noise when the engine speed decreases due to deceleration. This prior art is constructed so as to reduce the turbo rotation by performing regenerative control when the engine rotation speed becomes a threshold value or less. However, the problem with this prior art is that it is a measure that can only be applied to a supercharger with an electric motor, that the control may be activated when it is not necessary, or that the control may not be activated when necessary. That is, the operation is limited during deceleration.

  The cause of the occurrence of the above problem is that the first is the configuration that reduces the turbo rotation by the regeneration of the electric motor, and the second is the configuration that determines the level of the background noise level only by the engine rotation. The third is that the control is limited during deceleration. In particular, the second cause is that unnecessary control works when background noise is high even when the engine speed is low, and it is desired to reduce turbo noise when the background noise is low even though the engine speed is high. Nevertheless, the control does not work. The case where the background noise is high although the engine speed is low is, for example, the case where the vehicle speed is high and road noise and wind noise are large. The case where the background noise is low although the engine speed is high is, for example, a case where the vehicle speed is low and road noise and wind noise are low.

  In this regard, according to the embodiment, when the turbo rotation speed is inside the predetermined turbo rotation speed range, it is possible to adjust the turbo rotation speed so as to quickly get out of the rotation speed range. The predetermined turbo rotation speed range is set to a specific turbo rotation speed range in which the turbo sound increases based on the frequency characteristics of the body and the exhaust system parts. According to such a control operation, the turbo sound is suppressed from being transmitted to the occupant at the time of acceleration or deceleration, and as high as possible even when it is necessary to reduce the turbo rotation speed in consideration of NV. The rotation speed can also be maintained. Further, in step S102, it is determined whether to adjust the turbo rotation speed in consideration of the background noise level of the vehicle. Therefore, the problem which arises in relation to the background noise described above can also be solved.

  FIG. 7 is a control flowchart executed in the control device for the supercharger-equipped internal combustion engine according to the modification of the embodiment. The control routine shown in FIG. 7 is executed in a two-stage turbocharged internal combustion engine including an HP turbo and an LP turbo. The two-stage turbo system may be one in which two turbochargers of a low pressure stage and a high pressure stage are arranged in series. A compressor impeller of a low-pressure turbocharger (ie, LP turbo) is disposed upstream of the intake air flow so as to compress the intake air flowing through the intake passage. A compressor impeller of a turbocharger (that is, HP turbo) having a relatively small capacity and a high-pressure stage is disposed downstream of the LP turbo.

  Steps S200, S202, and S204 are the same processes as steps S100, S102, and S104 of the routine shown in FIG. However, in step S204, in addition to the control for deviating the turbo rotation speed of the HP turbo from the unacceptable range according to the same control as in step S104, the control for compensating for the shortage of supercharging by supercharging the LP turbo is included. It is.

  Steps S206, S208, and S210 are the same processes as steps S100, S102, and S104 of the routine of FIG. 1 described above for LP turbo. However, in step S210, in addition to the control that causes the turbo rotation speed of the LP turbo to deviate from the unacceptable range according to the control similar to step S104 described above, the control for compensating for the shortage of supercharging by supercharging the HP turbo is included. It is.

Claims (1)

Obtaining means for obtaining a turbo rotation speed of a turbocharger that supercharges intake air of the internal combustion engine;
Determining means for determining whether or not the turbo rotation speed is within a predetermined turbo rotation speed range;
When the turbo rotational speed is within the predetermined turbo rotational speed range, the engine rotational speed of the internal combustion engine decreases so that the turbo rotational speed decreases during deceleration where the engine rotational speed of the internal combustion engine decreases. Adjusting means for adjusting the turbo rotational speed of the turbocharger such that the turbo rotational speed increases during ascending acceleration;
A control device for an internal combustion engine with a supercharger.

Images