JP2018178890A - Internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily adjust the consumption of a battery in assist control and a power generation amount in power generation control in response to a request in an internal combustion engine equipped with an electric assist supercharger.SOLUTION: In assist control by an electric assist supercharger, a motor is driven by the electric power supplied from a battery to assist the rotation of a compressor. In power generation control, the battery is charged with the electric power which the motor generates with the rotation of the compressor. In the case where there is a request for reducing a power generation amount in the power generation control, a request for accelerating the consumption of the battery in the assist control, or a request for reducing the rotation speed of the compressor, a load on the compressor is increased. In the case where there is a request for increasing a power generation amount in the power generation control or a request for suppressing the consumption of the battery in the assist control, a load on the compressor is reduced.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an internal combustion engine provided with a motor-driven assist turbocharger.

  The electric assist turbocharger is a turbocharger equipped with a motor. For example, in a state where the rotational speed of the turbocharger is low, assist control is performed to drive the motor by the power supplied from the battery and assist the rotation of the turbocharger. Also, for example, when the rotational speed of the supercharger is high, the motor is driven as a generator by the rotation of the supercharger, and power generation control is performed to charge the battery.

  Patent Document 1 discloses a technique for suppressing sudden assist stop or generation stop of a motor in an electric assist turbocharger. Specifically, the motor control amount is determined so that the predetermined control parameter does not reach the limit value. The predetermined control parameters include motor temperature, inverter temperature, battery charge state, and the like.

  Patent Document 2 discloses a control device of a gas turbine which drives a turbine by combustion gas. The combustion gas is generated by the combustion of a mixture of air and fuel compressed by the compressor. Upstream of the compressor, an inlet guide vane (IGV: Inlet Guide Vane) is provided to control the flow rate of air introduced into the compressor. The opening degree of the inlet guide vanes is calculated based on, for example, the rotational speed of a generator connected to the turbine.

  Patent Document 3 discloses an internal combustion engine in which an electric compressor is provided in an intake passage. The output of the electric compressor is adjusted in accordance with the rate of increase of the charge amount of the battery that supplies power to the electric compressor.

JP 2008-215199 A JP, 2014-047728, A JP, 2016-079821, A

  As described above, the internal combustion engine equipped with the electric assist turbocharger performs assist control and power generation control using a motor. In assist control, it is desirable to be able to adjust the consumption of the battery as required. In power generation control, it is desirable to be able to adjust the amount of power generation as required.

  In the case of Patent Document 1 described above, the assist amount or the power generation amount by the motor is controlled by adjusting the “motor control amount”. At this time, the motor control amount is determined such that the control parameter such as the motor temperature does not reach the limit value. That is, there are various restrictions on the adjustment of the motor control amount. Such constraints complicate control and inhibit free control.

  One object of the present invention is to provide a technique capable of easily adjusting the consumption of a battery in assist control and the amount of power generation in power generation control according to a request in an internal combustion engine provided with an electric assist turbocharger. is there.

In one aspect of the invention, an internal combustion engine is
An electric assist turbocharger comprising a compressor and a motor connected to a rotating shaft;
Assist control that drives the motor by power supplied from a battery to assist rotation of the compressor, and motor control that performs power generation control of charging the battery by power generated by the motor by rotation of the compressor A device,
And a compressor load control device for controlling a compressor load which is a load applied to the rotation of the compressor.
When there is a request to reduce the amount of power generation in the power generation control, a request to accelerate the consumption of the battery in the assist control, or a request to reduce the rotational speed of the compressor, the compressor load control device Increase the load.
When there is a request to increase the amount of power generation in the power generation control or a request to suppress the consumption of the battery in the assist control, the compressor load control device reduces the compressor load.

  An internal combustion engine according to the present invention includes a compressor load control device that controls a compressor load. The compressor load contributes to the amount of power generation in power generation control and the consumption of the battery in assist control. For example, when the compressor load decreases, the amount of power generation in power generation control increases, and battery consumption in assist control is suppressed. On the other hand, when the compressor load increases, the amount of power generation in the power generation control decreases and the consumption of the battery in the assist control is promoted. By controlling the compressor load using the compressor load control device, it is possible to appropriately adjust the consumption of the battery in the assist control and the power generation amount in the power generation control according to the request.

  Further, according to the present invention, control of “compressor load” is performed instead of “motor control amount” as in the case of Patent Document 1 described above. Control of the compressor load is independent of complex motor control and is not affected by various motor control constraints. That is, the degree of freedom of control based on the compressor load is high. It is possible to easily adjust the consumption of the battery in the assist control and the amount of power generation in the power generation control only by increasing or decreasing the compressor load.

FIG. 1 is a schematic view showing a configuration of an internal combustion engine according to an embodiment of the present invention. It is a conceptual diagram for demonstrating an example of the compressor load adjustment mechanism of the internal combustion engine which concerns on embodiment of this invention. FIG. 3 is a conceptual view showing a compressor load adjusting mechanism in the case of increasing a compressor load in the internal combustion engine according to the embodiment of the present invention. It is a conceptual diagram showing a compressor load adjustment mechanism in the case of reducing compressor load in an internal combustion engine concerning an embodiment of the invention.

  Embodiments of the present invention will be described with reference to the attached drawings.

1. Basic Configuration of Internal Combustion Engine FIG. 1 is a schematic view showing the configuration of an internal combustion engine according to an embodiment of the present invention. The internal combustion engine includes an engine body 1, an intake passage 2, an exhaust passage 3, an electric assist turbocharger 10, an inverter 50, a battery 60, and a control device 70.

  The engine body 1 has a combustion chamber in which combustion is performed. The intake passage 2 is for supplying intake gas to the combustion chamber of the engine body 1 and is disposed upstream of the engine body 1. On the other hand, the exhaust passage 3 is for discharging exhaust gas from the combustion chamber of the engine body 1 and is disposed downstream of the engine body 1.

  The electric assist turbocharger 10 includes a compressor 20 and a turbine 30. The compressor 20 is provided in the intake passage 2, and the turbine 30 is provided in the exhaust passage 3. Further, the compressor 20 and the turbine 30 are connected to each other via a rotating shaft 25. When the turbine 30 is rotated by the exhaust gas flow from the combustion chamber of the engine body 1, the compressor 20 is also rotated, thereby compressing the intake gas. The compressed intake gas is supplied to the combustion chamber of the engine body 1 via the intercooler 4.

  The electric assist turbocharger 10 further includes a motor 40. The motor 40 is also connected to the rotating shaft 25. Therefore, the rotation of the compressor 20 and the turbine 30 can be assisted by supplying power to the motor 40 to rotate the motor 40. Conversely, the motor 40 can also be used as a generator. Specifically, power can be generated by rotating the motor 40 by the rotation of the compressor 20 and the turbine 30.

  A rotational speed sensor 15 is attached to the electric assist turbocharger 10. The rotational speed sensor 15 detects the rotational speed Nt of the electric assist turbocharger 10. The rotational speed Nt of the electric assist turbocharger 10 is the rotational speed of the rotating shaft 25, the compressor 20, the turbine 30, or the motor 40. The rotational speed sensor 15 sends detection information indicating the detected rotational speed Nt to the control device 70.

  The motor 40 of the electric assist turbocharger 10 is connected to the battery 60 via the inverter 50. The inverter 50 performs power conversion when exchanging power between the motor 40 and the battery 60. As will be described later, the operation of this inverter 50 is controlled by the controller 70.

  The battery 60 functions as a power source and a storage battery. That is, the electrical energy stored in the battery 60 is used for the operation of various electrical components including the motor 40. Further, when the motor 40 generates power as a generator, the battery 60 is charged by the electrical energy obtained by the power generation. An SOC sensor 65 is attached to the battery 60. The SOC sensor 65 detects the state of charge (SOC) of the battery 60 and sends detection information to the control device 70.

  Control device 70 controls the operation of the internal combustion engine. The control device 70 is typically a microcomputer provided with a processor, a storage device, and an input / output interface. Control device 70 is also referred to as an ECU (Electronic Control Unit). The control device 70 receives detection information from various sensors, controls various actuators based on the received detection information, and controls the operation of the internal combustion engine. Such control is realized by the processor of the control device 70 executing a control program stored in the storage device.

  In particular, the control device 70 according to the present embodiment performs “motor control” and “compressor load control”. Hereinafter, each of motor control and compressor load control according to the present embodiment will be described in detail.

2. Motor control 2-1. Assist Control First, “assist control” will be described as an example of motor control. The assist control is a control that drives the motor 40 by the power supplied from the battery 60 to assist the rotation of the compressor 20 (that is, the electric assist turbocharger 10).

  More specifically, control device 70 controls inverter 50 such that power is supplied from battery 60 to motor 40. At this time, the inverter 50 converts DC power discharged from the battery 60 into AC power, and supplies AC power to the motor 40. The motor 40 is rotated by the power supplied from the battery 60 and applies an assist torque to the rotating shaft 25. The rotation of the compressor 20 and the turbine 30 is assisted by the assist torque.

2-2. Power Generation Control Next, “power generation control” will be described as another example of motor control. The power generation control is control for charging the battery 60 with the power generated by the motor 40 by the rotation of the compressor 20 (that is, the electric assist turbocharger 10).

  More specifically, the rotation of the compressor 20 causes the motor 40 to function as a generator to generate electricity. Control device 70 controls inverter 50 such that the electric power generated by motor 40 (generator) is supplied to battery 60. At this time, the inverter 50 converts AC power output from the motor 40 into DC power, and supplies DC power to the battery 60. Thereby, the battery 60 is charged.

2-3. Motor Control Device As shown in FIG. 1, the inverter 50, the battery 60, and the control device 70 constitute a “motor control device 100” that performs motor control. The motor control device 100 performs the above-described assist control and power generation control on the motor 40 of the electric assist turbocharger 10.

3. Compressor load control 3-1. Overview Various requirements may occur for the above-described assist control and power generation control as follows.

  As an example, it is assumed that the charge amount of the battery 60 is small. If the charge amount of the battery 60 is insufficient, the function of the electrical component using the battery 60 as a power source may be degraded or stopped. Therefore, in the power generation control, a request to increase the amount of power generation by the motor 40 (generator) may occur. Alternatively, in the assist control, a request may be generated to reduce the amount of power supplied from the battery 60 to the motor 40, that is, to suppress the consumption of the battery 60.

  As another example, it is assumed that the battery 60 is fully charged or overcharged. When the battery 60 is overcharged, the battery 60 is degraded. Therefore, in the power generation control, a request to reduce the number of generators by the motor 40 (generator) may occur. Alternatively, in the assist control, a request may be generated to increase the amount of power supplied from the battery 60 to the motor 40, that is, to promote the consumption of the battery 60.

  As still another example, consider the case where the compressor 20 is in the overrotation state. In this case, it is desirable to reduce the rotational speed Nt of the compressor 20 in the assist control.

  In order to satisfy such various requirements, according to the present embodiment, control of the “compressor load” is performed. The compressor load is a load applied to the rotation of the compressor 20. By appropriately increasing or decreasing the compressor load, it is possible to meet the various requirements described above.

  As an example, consider a case where there is a demand to increase the amount of power generation by the motor 40 (generator) in power generation control. In this case, the compressor load may be "reduced". As the compressor load decreases, the rotational speed Nt tends to increase, and the amount of power generation by the motor 40 and the power generation efficiency increase.

  As another example, consider a case where there is a demand to reduce the amount of power generation by the motor 40 (generator) in power generation control. In this case, the compressor load may be "increased". As the compressor load increases, the rotational speed Nt tends to decrease, and the amount of power generation by the motor 40 and the power generation efficiency decrease.

  As still another example, it is assumed that there is a request for promoting the consumption of the battery 60 in the assist control. In this case, the compressor load may be "increased". The increase in compressor load increases the amount of power required to rotate the compressor 20 and promotes consumption of the battery 60.

  As still another example, it is assumed that there is a request for suppressing the consumption of the battery 60 in the assist control. In this case, the compressor load may be "reduced". By reducing the compressor load, the amount of power required to rotate the compressor 20 is reduced, and the consumption of the battery 60 is suppressed.

  As still another example, consider a case where it is required to reduce the rotational speed Nt of the compressor 20 in order to prevent an over-rotation state. In this case, the compressor load may be "increased". The increase in the compressor load makes it difficult for the compressor 20 to rotate, and the rotational speed Nt of the compressor 20 decreases.

3-2. Compressor Load Control Device As shown in FIG. 1, the internal combustion engine according to the present embodiment further includes a compressor load adjustment mechanism 80. The compressor load adjustment mechanism 80 is a mechanism for adjusting the compressor load, and is provided in the intake passage 2 upstream of the compressor 20.

  FIG. 2 is a conceptual diagram for explaining an example of the compressor load adjustment mechanism 80. As shown in FIG. In FIG. 2, the rotational direction of the rotor blade 21 of the compressor 20 is represented by the “F direction”. The direction opposite to the F direction, that is, the direction opposite to the rotation direction of the rotor blade 21 of the compressor 20 is represented by “R direction”.

  The compressor load adjusting mechanism 80 is configured to be able to adjust the direction of the intake gas input to the compressor 20. In the example shown in FIG. 2, the compressor load adjustment mechanism 80 has a variable inlet guide vane 81 located upstream of the inlet of the compressor 20. The variable inlet guide vanes 81 are rotatable about an axis 82. By changing the inclination of the variable inlet guide vane 81, it is possible to adjust the direction of the intake gas input to the compressor 20.

  FIG. 3 shows the case of increasing the compressor load. In this case, the inclination of the variable inlet guide vane 81 is set such that the “R direction component” is added to the direction of the intake gas input to the compressor 20. Since the component opposite to the rotation direction of the compressor 20 increases, the amount of work that the compressor 20 has to do with the intake gas increases. That is, the compressor load increases.

  FIG. 4 shows the case of reducing the compressor load. In this case, the inclination of the variable inlet guide vane 81 is set such that the “F direction component” is added to the direction of the intake gas input to the compressor 20. As the same component as the rotational direction of the compressor 20 increases, the amount of work that the compressor 20 has to do with the intake gas decreases. That is, the compressor load is reduced.

  Thus, by controlling the inclination of the variable inlet guide vanes 81, it is possible to control the compressor load. The tilt of the variable inlet guide vane 81 is appropriately controlled by the controller 70. As shown in FIG. 1, it can be said that the control device 70 and the compressor load adjustment mechanism 80 constitute a “compressor load control device 200” that controls the compressor load.

3-3. Specific Example of Compressor Load Control The controller 70 receives information on the rotational speed Nt from the rotational speed sensor 15, and receives information on the charge state of the battery 60 from the SOC sensor 65. Then, the control device 70 appropriately controls the compressor load based on the rotational speed Nt and the charge state of the battery 60.

  For example, based on the charge state of the battery 60, the control device 70 determines whether the charge amount of the battery 60 is insufficient. For example, when the charge amount of the battery 60 is less than the first threshold, the control device 70 determines that the charge amount of the battery 60 is insufficient. In this case, it is desirable to increase the amount of power generation by the motor 40 (generator) in the power generation control, and it is desirable to suppress the consumption of the battery 60 in the assist control. In order to meet such requirements, the controller 70 (compressor load controller 200) reduces the compressor load (see FIG. 4). As a result, the power generation amount is increased in the power generation control, and the consumption of the battery 60 is suppressed in the assist control.

  As another example, control device 70 determines whether battery 60 is fully charged or overcharged based on the charge state of battery 60. For example, when the charge amount of the battery 60 is equal to or greater than the second threshold, the control device 70 determines that the battery 60 is in a fully charged state or in an overcharged state. In this case, in the power generation control, it is desirable to reduce the amount of power generated by the motor 40 (generator), and in the assist control, it is desirable to promote the consumption of the battery 60. In order to satisfy such a demand, the controller 70 (compressor load controller 200) increases the compressor load (see FIG. 3). As a result, the amount of power generation decreases in the power generation control, and the consumption of the battery 60 is promoted in the assist control.

  As still another example, control device 70 determines whether compressor 20 is in the overrotation state based on the information on rotational speed Nt. For example, when the rotation speed Nt is equal to or higher than the third threshold, the control device 70 determines that the compressor 20 is in the overrotation state. In this case, it is desirable to reduce the rotational speed Nt of the compressor 20. In order to satisfy such a demand, the controller 70 (compressor load controller 200) increases the compressor load (see FIG. 3). As a result, the compressor 20 becomes difficult to rotate, and the rotational speed Nt of the compressor 20 decreases.

4. As described above, the internal combustion engine according to the present embodiment includes the compressor load control device 200 that controls the compressor load. The compressor load contributes to the amount of power generation in power generation control and the consumption of the battery in assist control. For example, when the compressor load decreases, the amount of power generation in the power generation control increases, and the consumption of the battery 60 in the assist control is suppressed. On the other hand, when the compressor load increases, the amount of power generation in power generation control decreases, and consumption of the battery 60 in assist control is promoted. By controlling the compressor load using the compressor load control device 200, it is possible to appropriately adjust the consumption of the battery 60 in the assist control and the power generation amount in the power generation control according to the request.

  Further, according to the present embodiment, control of “compressor load” is performed instead of “motor control amount” as in the case of Patent Document 1 described above. Control of the compressor load is independent of complex motor control and is not affected by various motor control constraints. That is, the degree of freedom of control based on the compressor load is high. It is possible to easily adjust the consumption of the battery 60 in the assist control and the amount of power generation in the power generation control only by increasing or decreasing the compressor load. Further, since it is not necessary to adjust the motor control amount having many restrictions, it is possible to prevent the complicated motor control from being further complicated.

  Furthermore, when the variable inlet guide vane 81 illustrated in FIGS. 2 to 4 is used as the compressor load adjusting mechanism 80, the compressor load can be easily increased or decreased by changing the inclination thereof. That is, by using only one component, the variable inlet guide vane 81, it is possible to cope with both increase and decrease of the compressor load. This is preferable from the viewpoint of cost reduction, improvement in engine mountability, and reduction in engine weight.

Reference Signs List 1 engine body 2 intake passage 3 exhaust passage 4 intercooler 10 electric assist turbocharger 15 rotational speed sensor 20 compressor 21 rotor blade 25 rotary shaft 30 turbine 40 motor 50 inverter 60 battery 65 SOC sensor 70 control unit (ECU)
Reference Signs List 80 compressor load adjusting mechanism 81 variable inlet guide vane 82 axis 100 motor controller 200 compressor load controller

Claims (1)

An electric assist turbocharger comprising a compressor and a motor connected to a rotating shaft;
Assist control that drives the motor by power supplied from a battery to assist rotation of the compressor, and motor control that performs power generation control of charging the battery by power generated by the motor by rotation of the compressor A device,
A compressor load control device for controlling a compressor load which is a load applied to the rotation of the compressor;
When there is a request to reduce the amount of power generation in the power generation control, a request to accelerate the consumption of the battery in the assist control, or a request to reduce the rotational speed of the compressor, the compressor load control device Increase the load,
The compressor load control device reduces the compressor load when there is a request to increase the amount of power generation in the power generation control or a request to suppress consumption of the battery in the assist control.

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