JP2016114046A - Internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an internal combustion engine that includes an electric compressor and of which output reduction can be suppressed.SOLUTION: An internal combustion engine includes: an electric compressor provided in an intake passage of the internal combustion engine; a throttle valve provided in the intake passage downstream of the electric compressor; a bypass passage for communicating the intake passage upstream of the electric compressor with the intake passage downstream of the throttle valve; a bypass valve provided in the bypass passage; and a control device for determining rotational frequency of prerotation of the electric compressor on the basis of the speed of the internal combustion engine and maximum electric power consumption of the electric compressor and fully opening the throttle valve to enable prerotation of the electric compressor.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an internal combustion engine.

  2. Description of the Related Art Conventionally, an internal combustion engine including an electric compressor provided in an intake passage and a bypass passage that bypasses the electric compressor is known. It is known that an electric compressor takes time to reach a desired rotational speed from an operation stop state.

  Patent Document 1 discloses a technique for pre-rotating an electric compressor. The pre-rotation of the electric compressor means that the electric compressor is driven in advance when the operation state of the internal combustion engine is in the pre-rotation region. By pre-rotating the electric compressor, it is possible to shorten the time until the electric compressor reaches a desired rotation speed.

JP 2006-233879 A JP-A-7-145734

  However, in the technique of Patent Document 1, during the pre-rotation of the electric compressor, the intake air that has been supercharged by the electric compressor circulates through the bypass passage, which may increase the intake air temperature. When the intake air temperature increases, the output of the internal combustion engine may decrease.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an internal combustion engine that can suppress a decrease in the output of an internal combustion engine that includes an electric compressor.

In order to achieve the above object, a first invention provides an internal combustion engine,
An electric compressor provided in the intake passage of the internal combustion engine;
A throttle valve provided in an intake passage on the downstream side of the electric compressor;
A bypass passage communicating the intake passage on the upstream side of the electric compressor and the intake passage on the downstream side of the throttle valve;
A bypass valve provided in the bypass passage;
Based on the rotational speed of the internal combustion engine and the maximum power consumption of the electric compressor, the rotational speed of the pre-rotation of the electric compressor is determined, the bypass valve is fully opened, and the throttle valve is fully closed to A control device for pre-rotating the compressor;
It is characterized by providing.

  According to the first aspect, since the throttle valve is closed during the pre-rotation, the intake air discharged from the electric compressor by the pre-rotation does not flow backward in the bypass passage. For this reason, the backflowed intake air is not compressed again by the electric compressor, and an increase in intake air temperature can be suppressed. As a result, a decrease in engine output due to an increase in intake air temperature can be suppressed.

1 is a diagram illustrating a configuration of a system according to a first embodiment. It is a figure showing the operating area of an engine. It is a figure showing about the map which determines the rotational speed of pre-rotation. It is the figure which showed the operating line on the map which determines the rotational speed of pre-rotation. It is a figure showing the pre-rotation control flow performed by ECU of Embodiment 1. FIG.

Embodiment 1 FIG.
[System configuration]
FIG. 1 is a diagram showing the configuration of the system according to the first embodiment. FIG. 1 shows an engine body 8. An intake manifold 7 and an exhaust manifold 9 are attached to the engine body 8. An intake passage 13 is connected to the intake manifold 7. An exhaust passage 14 is connected to the exhaust manifold 9.

  In the intake passage 13, an electric compressor 1, a turbo compressor 3, and an intercooler 4 are provided in order from the upstream. The turbo compressor 3 is a device that constitutes a turbocharger that compresses intake air using exhaust gas. The electric compressor 1 includes an impeller stored in a casing and a motor 16 that rotates the impeller. The electric compressor 1 is a device that compresses intake air by driving a motor 16 by electricity to rotate an impeller. The electric compressor 1 is provided for the purpose of compensating for the supercharging pressure when the turbo lag of the turbocharger is generated, and assisting supercharging during rapid acceleration.

  Further, a bypass passage 15 that connects the intake passage 13 upstream of the electric compressor 1 and the intake passage 13 between the electric compressor 1 and the turbo compressor 3 is connected to the intake passage 13. The bypass passage 15 is provided with a bypass valve 2 that opens and closes the bypass passage 15.

  Further, a throttle valve 10 is provided between the electric compressor 1 and the turbo compressor 3. The throttle valve 10 is provided in the intake passage 13 upstream of the connection portion between the intake passage 13 and the downstream end of the bypass passage 15. The throttle valve 10 adjusts the flow rate of the air discharged from the electric compressor 1.

  The exhaust passage 14 is provided with a turbine 11 that is a device constituting a turbocharger. As the exhaust gas passes through the turbine 11, the turbine 11 rotates, and the turbo compressor 3 rotates in conjunction with the rotation.

  The system configuration of the first embodiment includes an ECU 100 (Electronic Control Unit) as a control device that controls the operating state of the engine body 8. An engine speed sensor (not shown) is connected to the input side of the ECU 100. ECU 100 detects the engine speed from the signal output by the engine speed sensor.

  An actuator such as the electric compressor 1, the bypass valve 2, and the throttle valve 10 is connected to the output side of the ECU 100. The ECU 100 outputs a drive signal to the electric compressor 1 to drive the electric compressor 1. The ECU 100 outputs a signal to the bypass valve 2 to adjust the opening degree of the bypass valve 2. The ECU 100 outputs a signal to the throttle valve 10 to adjust the opening degree of the throttle valve 10.

  In the first embodiment, in order to improve the response of the electric compressor 1, pre-rotation control is performed in which the electric compressor 1 is rotated in advance before the assist by the electric compressor 1 is started. Hereinafter, the operation region in which the pre-rotation control of the electric compressor is performed will be described with reference to FIG.

  FIG. 2 is a diagram showing an engine operating region. FIG. 2 shows the torque on the vertical axis and the engine speed on the horizontal axis. A solid line in FIG. 2 indicates a supercharging region by the electric compressor 1. A pre-rotation region is set in the supercharging region (shaded portion in FIG. 2) of the electric compressor 1.

  When the operating state of the engine is in the pre-rotation region shown in FIG. 2, the electric compressor 1 is driven to rotate in advance so that supercharging can be started immediately. In addition, as shown in FIG. 2, in the region where the response can be obtained without performing the pre-rotation of the engine speed Ne2 or more, or in the low-speed region such as the time of engine start where the engine speed is Ne1 or less, Is not done.

  In the pre-rotation region, the pre-rotation speed of the electric compressor 1 is determined based on a map stored in the ECU 100 in advance. Hereinafter, a map for determining the rotation speed of the pre-rotation of the electric compressor 1 will be described with reference to FIG.

  FIG. 3 is a diagram showing a map for determining the rotation speed of the pre-rotation. In FIG. 3, the vertical axis represents the pressure (pressure ratio with respect to atmospheric pressure) of the discharge portion of the electric compressor 1, and the horizontal axis represents the corrected air flow rate at the discharge portion of the electric compressor 1.

  In the map of FIG. 3, the solid lines displaying the rotational speeds of Y1 rpm, Y2 rpm, and Y3 rpm are the isoelectric compressor rotational speed lines when the electric compressor 1 is rotated at this rotational speed. A broken line is a maximum motor power consumption line of the motor 16 of the electric compressor 1. An alternate long and short dash line is an equal engine rotation speed line when the engine is operated at a constant rotation speed.

  In the map shown in FIG. 3, the rotational speed of the pre-rotation of the electric compressor 1 is determined from the intersection of the engine rotational speed and the maximum power consumption. For example, as shown by a point A in FIG. 3, under the condition that the engine speed is Z rpm and the maximum motor power consumption is X kW, the pre-rotation speed of the electric compressor 1 is set to Y2 rpm. Point A is the rotation speed of the pre-rotation in the above-mentioned condition in a state where the bypass valve 2 is fully closed and the opening of the throttle valve 10 is fully open.

  Hereinafter, a state in which the bypass valve 2 is fully closed and the opening degree of the throttle valve 10 is fully open will be referred to as a comparative example.

  Here, the pre-rotation control of the first embodiment is performed in a state in which the bypass valve 2 is fully opened and the throttle valve 10 is fully closed. This will be described below using point B.

  Point B in FIG. 3 shows a state where the bypass valve 2 is fully opened and the throttle valve 10 is fully closed under the same conditions of the engine speed and motor power consumption in the comparative example. Thus, the electric compressor 1 can be pre-rotated in the surge region by fully closing the throttle valve 10.

  Next, changes in the pressure ratio and the air flow rate when the pre-rotation control of the first embodiment is performed will be described with reference to FIG.

  FIG. 4 is a diagram showing an operating line on a map for determining the rotation speed of the pre-rotation. The arrows indicated by I and II in FIG. 4 indicate changes in the pressure ratio and the air flow rate of the comparative example. When the electric compressor 1 is pre-rotated with the bypass valve 2 fully closed and the throttle valve 10 fully open, the air flow rate first increases (arrow I), and then the pressure ratio increases. (Arrow II).

  On the other hand, arrows indicated by I ′, II ′, and III ′ in FIG. 4 indicate changes in the pressure ratio and the air flow rate in the first embodiment. If the electric compressor 1 is pre-rotated with the bypass valve 2 fully opened and the throttle valve 10 fully closed, the throttle valve 10 is fully closed, so the pressure ratio first increases (arrow). I '). Next, since the air compressed by the electric compressor 1 flows from the bypass passage 15, the air flow rate increases along the isoelectric compressor rotation speed line (arrow II '). Thereafter, the pressure ratio increases again (arrow III ').

  Thus, by performing the pre-rotation control of the electric compressor 1 in the first embodiment, the electric compressor 1 can be pre-rotated in the surge region. For this reason, it can be made to pre-rotate, suppressing the motor power consumption of the electric compressor 1. FIG. Further, during acceleration, the operation line of the electric compressor 1 passes through the equal rotation line. For this reason, the drive of the electric compressor 1 can be made highly efficient, and the inertia loss at the time of the drive of the electric compressor 1 reduces simultaneously. As a result, the pressure ratio increases more quickly than when the pre-rotation control of the first embodiment is not performed.

  Furthermore, in Embodiment 1, since the throttle valve 10 is closed during the pre-rotation, the intake air discharged from the electric compressor 1 due to the pre-rotation does not flow backward in the bypass passage 15. For this reason, the backflowed intake air is not compressed again by the electric compressor 1, and an increase in intake air temperature can be suppressed. As a result, a decrease in engine output due to an increase in intake air temperature can be suppressed.

  Hereinafter, the pre-rotation control flow of the electric compressor 1 will be described with reference to FIG.

[Pre-rotation control flow]
FIG. 5 is a diagram illustrating a pre-rotation control flow executed by ECU 100 of the first embodiment. First, the ECU 100 determines whether or not the pre-rotation region (S100). The ECU 100 determines whether or not the current engine operation region is the pre-rotation region described with reference to FIG. If it is determined that it is not in the pre-rotation region, the pre-rotation control ends.

  On the other hand, when it is determined in S100 that it is the pre-rotation region, the ECU 100 determines the pre-rotation rotation speed from the engine rotation speed Ne and the motor maximum power consumption (S102). The rotation speed of the pre-rotation is determined using the map described in FIG.

  Next, the ECU 100 performs pre-rotation of the electric compressor 1 (S104). Here, the pre-rotation of the electric compressor 1 is performed with the bypass valve 2 fully opened and the throttle valve 10 fully closed.

  Next, the ECU 100 determines whether there is an acceleration request (S106). The acceleration request here means a request to drive the electric compressor 1 when compensating for the supercharging pressure when the turbo lag of the turbocharger occurs or assisting the supercharging during the rapid acceleration. If it is determined that there is no acceleration request, ECU 100 executes S100 again.

  On the other hand, when it is determined that there is an acceleration request, the ECU 100 starts assisting the electric compressor 1 (S108). The assist of the electric compressor 1 means that when there is a request for acceleration of the electric compressor 1, the electric compressor 1 shifts from the pre-rotation region to the supercharging region and performs supercharging by the electric compressor 1.

  Next, when fully closing the bypass valve 2 and fully opening the throttle valve 10, the ECU 100 performs control so that the throttle valve 10 is fully opened first (S110). In S110, when assisting the electric compressor 1, the opening / closing order of the respective valves when the throttle valve 10 is opened and the bypass valve 2 is closed is controlled. By executing S110, it is possible to prevent both the bypass valve 2 and the throttle valve 10 from being fully closed.

  Next, the ECU 100 determines whether or not the assist is turned off (S112). Here, assist-off means that the electric compressor 1 stops when the electric compressor 1 is driven to obtain a desired engine output. If it is determined that the assist is not turned off, the assist is continued and the process of S112 is executed again.

  On the other hand, when ECU 100 determines that the assist is turned off, ECU 100 ends the pre-rotation control.

DESCRIPTION OF SYMBOLS 1 Electric compressor 2 Bypass valve 8 Engine main body 10 Throttle valve 13 Intake passage 15 Bypass passage 16 Motor 100 ECU

Claims (1)

An electric compressor provided in the intake passage of the internal combustion engine;
A throttle valve provided in an intake passage on the downstream side of the electric compressor;
A bypass passage communicating the intake passage on the upstream side of the electric compressor and the intake passage on the downstream side of the throttle valve;
A bypass valve provided in the bypass passage;
Based on the rotational speed of the internal combustion engine and the maximum power consumption of the electric compressor, the rotational speed of the pre-rotation of the electric compressor is determined, the bypass valve is fully opened, and the throttle valve is fully closed to A control device for pre-rotating the compressor;
An internal combustion engine comprising:

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