JP2020165400A - Engine control device and engine control method - Google Patents

Abstract

To provide an engine control device and an engine control method capable of reducing costs of a system while realizing high power generation efficiency.SOLUTION: An engine control device includes a control portion. The control portion controls an engine to generate electric power to be supplied to a motor as a power source of a vehicle. The engine is not provided with a throttle valve of which an opening is changed according to an operation state of an accelerator pedal in an intake passage, and a diameter of the intake passage is determined to such a diameter that the air providing a first operation region in which heat efficiency of the engine is a prescribed value or more, is passed therethrough. The control portion starts at least one of fuel injection control and ignition control of the engine when an engine rotating speed approaches a value corresponding to the first operation region.SELECTED DRAWING: Figure 1

Description

The present invention relates to an engine control device and an engine control method.

Conventionally, a range extender system, which is a control system installed for the purpose of extending the cruising range of an electric vehicle, is known. In such a control system, the engine is not used as the running power of the vehicle, but is used to drive the generator (see, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2012-184695

However, with the conventional technology, there is room for improvement in terms of reducing the cost of the system while achieving high power generation efficiency.

The present invention has been made in view of the above, and an object of the present invention is to provide an engine control device and an engine control method capable of reducing the cost of a system while realizing high power generation efficiency.

The engine control device according to the present invention includes a control unit in order to solve the above-mentioned problems and achieve the object. The control unit controls an engine for generating electric power to be supplied to a motor which is a power source of a vehicle. The engine is not provided with a throttle valve whose opening degree changes according to the operating state of the accelerator pedal in the intake path, and the diameter of the intake path is such that the thermal efficiency of the engine is equal to or higher than a predetermined value. It is set to a diameter that allows the amount of air that is the operating range to pass through. Further, the control unit starts at least one of the fuel injection control and the ignition control of the engine when the engine speed becomes close to the value corresponding to the first operating region.

According to the present invention, it is possible to reduce the cost of the system while realizing high power generation efficiency.

FIG. 1 is a block diagram showing a configuration of a control system according to an embodiment. FIG. 2 is a diagram showing an outline of the engine control method according to the embodiment. FIG. 3 is a timing chart showing the control timing of the control system. FIG. 4 is a flowchart showing a processing procedure of processing executed by the engine control device according to the embodiment.

Hereinafter, embodiments of the engine control device and the engine control method disclosed in the present application will be described in detail with reference to the accompanying drawings. The present invention is not limited to the embodiments shown below.

First, the outline of the engine control method according to the embodiment will be described with reference to FIGS. 1 and 2. FIG. 1 is a block diagram showing a configuration of a control system according to an embodiment. FIG. 2 is a diagram showing an outline of the engine control method according to the embodiment.

As shown in FIG. 1, the control system S according to the embodiment includes an engine control device 1, an engine 2, a power generation device 3, a battery 4, a drive device 5, and a battery monitor 6. The control system S according to the embodiment is mounted on a vehicle powered by a motor, such as an electric vehicle.

The engine 2 is an engine for generating electric power to be supplied to the motor 52, which is a power source of the vehicle. That is, the engine 2 is not used as a power source for the vehicle. As the engine 2, any engine such as a gasoline engine or a diesel engine can be adopted.

Further, the engine 2 is designed so that the diameter of the intake path in the intake manifold is such that the amount of air driven by the maximum thermal efficiency can be ventilated in advance. And the engine 2 does not have a throttle valve for adjusting the intake air amount. Therefore, the diameter of the intake path is designed so that the intake amount in the absence of the throttle valve becomes the target air amount. That is, the intake path of the engine of the Honjin mobile phone is not provided with a valve whose opening degree changes according to the accelerator pedal operated by the driver (the bypass valve is also a valve that is controlled regardless of the accelerator pedal). The engine 2 has a bypass path that bypasses the intake path as a mechanism for finely adjusting the amount of air, and this point will be described later.

The power generation device 3 includes a motor generator 31 and an inverter 32, and functions as a generator that generates electric power by the rotational energy of the engine 2. The power generation device 3 also functions as a starter for starting the engine 2 using the electric power of the battery 4.

When the power generation device 3 functions as a generator, the motor generator 31 generates electric power by the rotational energy of the engine 2 and outputs the generated electric power to the inverter 32. Then, the inverter 32 converts the electric power obtained from the motor generator 31 from alternating current to direct current and charges the battery 4. Further, the power generation device 3 generates electric power by the regenerative brake and charges the battery 4, for example.

When the power generation device 3 functions as a starter, the inverter 32 converts the electric power obtained from the battery 4 from direct current to alternating current and outputs it to the motor generator 31. The motor generator 31 starts and drives the engine 2 with the electric power obtained from the inverter 32.

The battery 4 is a secondary battery, for example, a lithium ion battery.

The drive device 5 includes an inverter 51 and a motor 52, and functions as a power source for the vehicle. The inverter 51 converts the electric power of the battery 4 from direct current to alternating current and outputs it to the motor 52. Then, the motor 52 is driven by AC power.

The battery monitor 6 is a detection device including a sensor for detecting the remaining amount of the battery 4. The battery monitor 6 outputs a power generation instruction to the engine control device 1 and the power generation device 3 when the remaining amount of the battery 4 becomes equal to or less than a predetermined threshold value. The power generation instruction is an instruction to start power generation in order to charge the battery 4. The control of the engine control device 1 and the power generation device 3 according to the power generation instruction will be described later in FIG.

The engine control device 1 includes a control unit 1a that controls the engine 2 and executes the engine control method according to the embodiment. Further, the engine control device 1 acquires the engine speed, the intake air amount, and the like with various sensors provided in the engine 2 and uses them for control.

Here, the engine control device 1 includes, for example, a computer having a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), a data flash, an input / output port, and various circuits.

The CPU of the computer functions as the control unit 1a by reading and executing the program stored in the ROM, for example.

Further, a part or all of the functions of the control unit 1a can be configured by hardware such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field Programmable Gate Array).

The engine control device 1 can also acquire the above-mentioned programs and various information via another computer or a portable recording medium connected by a wired or wireless network.

The control unit 1a controls the engine 2 for generating electric power supplied to the motor 52, which is a power source of the vehicle. Further, the engine 2 is controlled based on the intake amount set in the range corresponding to the control region, with the region where the thermal efficiency based on the control unit 1a rotation speed and torque is equal to or higher than a predetermined value as the control region (first operation region). To do. Specifically, the control unit 1a starts at least one of the fuel injection control and the ignition control of the engine 2 when the engine speed becomes close to the value corresponding to the first operating region. This point will be described with reference to FIG.

FIG. 2 is a diagram showing a control region of the control unit 1a. In FIG. 2, the relationship between the thermal efficiency and the rotation speed of the engine 2 and the torque is shown graphically. A plurality of ellipses are shown in the graph of FIG. 2, and each ellipse is a value of thermal efficiency, and the ellipse in the center has higher thermal efficiency. Further, in the engine 2 according to the present embodiment, the diameter of the intake path is set to a diameter that allows the amount of air to pass through the first operating region (the shaded elliptical region in FIG. 2) in which the thermal efficiency of the engine 2 is equal to or higher than a predetermined value. It is set. Further, in the present embodiment, a bypass path is provided in the intake path, and the amount of air can be adjusted in the first operating region according to the opening degree of the bypass valve. The bypass path and bypass valve may be omitted.

As shown in FIG. 2, the control unit 1a controls the engine 2 with the rotation speed and torque in the range where the thermal efficiency is near the maximum value (shaded ellipse in FIG. 2) as a control region. Further, since the torque and the charge amount are in a proportional relationship, the control system S can efficiently generate power, that is, can realize high power generation efficiency. Further, since the amount of intake air to the engine 2 is configured to be controllable only within a limited range as described above, the operating region (engine rotation speed) of the engine 2 is the first operating region such as when the engine is started. In the case of the outside, the motor 52 is driven and the regenerative brake is controlled so as to be within the first operating region.

Further, since the rotation speed and the amount of air are in a proportional relationship, the amount of air taken in by the engine 2 can be reduced by narrowing the control range of the rotation speed of the engine 2. That is, the engine 2 in the control system S does not need to be provided with a throttle valve because it is not necessary to adjust the intake amount widely. As a result, the cost of the control system S can be reduced.

Next, the control timing of the control system S will be described with reference to FIG. FIG. 3 is a timing chart showing the control timing of the control system S.

As shown in FIG. 3, at time t1, when the measured remaining battery level becomes equal to or less than the power generation start threshold value TH1, the battery monitor 6 gives a power generation instruction of “implementation” to the power generation device 3 and the engine control device 1. Output.

Then, at time t2, the power generation device 3 functions as a starter. Specifically, the power generation device 3 switches the operating state of the inverter 32 to the discharge operation, supplies the electric power of the battery 4 to the motor generator 31, and starts the engine 2 by the motor generator 31. As a result, the rotation speed of the engine 2 starts to increase from time t2.

Then, at time t3, when the rotation speed of the engine 2 reaches a predetermined value or more, the engine control device 1 performs fuel injection control and ignition processing of the engine 2. The rotation speed at which these processes are performed is the rotation speed near the control region described above. That is, the control unit 1a starts the engine 2 with the electric power charged in the battery 4 (time t2), drives the engine 2 to the number of revolutions corresponding to the control region, and then ignites the engine 2.

When the above engine rotation (or a rotation slightly higher than the above engine rotation) is reached, the drive of the motor generator 31 is stopped (that is, switched to power generation). Then, when the rotation speed at which the drive of the motor generator 31 is stopped drives the starter motor for starting the engine in a vehicle having only the engine 2, or when the motor generator 31 is driven for starting the engine in a normal HV vehicle. The rotation speed is set higher than the rotation speed at which the drive by the motor 52 is stopped. In the start control in the conventional engine-only vehicle or HV vehicle, the fuel injection control and the ignition control are started from a time earlier (lower engine speed) than in the present invention.

This is because the intake amount of the engine 2 is fixed to the amount corresponding to the control region, and the engine 2 is ignited by driving the electric power to the rotation speed corresponding to the control region and increasing the rotation speed in advance. It is possible to prevent it from stopping without stopping.

Then, at time t4, the power generation device 3 switches the function from the starter to the generator. Specifically, the power generation device 3 switches the operating state of the inverter 32 from the discharging operation to the charging operation. At this time, the power generation device 3 starts power generation at an initial value of a predetermined power generation amount.

Further, at time t4, the engine control device 1 outputs a charge amount request to the power generation device 3 because the engine speed rapidly increases when the injection / ignition starts to be executed. The charge amount request is information for instructing the amount of electric power to charge the battery 4. The power generation device 3 controls the inverter 32 based on the charge amount request to adjust the power generation amount. That is, the control unit 1a starts the engine 2 by the motor 52 when the battery 4 needs to be charged, but when it is determined that the engine speed has reached the speed corresponding to the first operating region, the motor 52 The control state is switched from the state in which the engine 2 is driven to the state in which the engine 2 generates electricity.

For example, at time t4, the engine control device 1 outputs a charge amount request of the charge request flag “UP” that increases the charge amount. This indicates that since the rotation speed of the engine 2 is lower than the control region, the rotation speed is increased after the time t4. That is, the engine control device 1 gives an instruction to increase the charge amount in order to increase the rotation speed after the time t4.

Then, the instantaneous charging power is gradually increased, the load torque applied to the engine is increased accordingly, the increase in the engine speed is stopped, and the engine speed starts to decrease at time t5. Then, at time t5, the engine control device 1 outputs a charge amount request of the charge request flag "DOWN" for reducing the charge amount, lowers the torque applied to the engine 2, and gradually approaches the target rotation speed. To. This indicates that the rotation speed of the engine 2 is higher than that in the control region, so that the rotation speed is reduced after the time t5. That is, the engine control device 1 gives an instruction to reduce the charge amount in order to reduce the rotation speed after the time t5.

Then, at time t6, the engine control device 1 outputs a charge amount request of the maintenance request flag "KEEP" for maintaining the charge amount, and controls to wait for the target rotation speed to be approached. This indicates that since the rotation speed of the engine 2 is near the control region, the rotation speed is maintained after the time t6. That is, the engine control device 1 gives an instruction to maintain the charge amount in order to maintain the rotation speed after the time t6. The charge request flag "UP" is output at time t7, because of fine adjustment control for adjusting to the target rotation speed.

Then, at time t8, when the rotation speed converges within the range of the control region, the engine control device 1 continuously outputs the charge amount request of "KEEP" for maintaining the charge amount after time t8. .. When the rotation speed goes out of the control range, the engine control device 1 adjusts the rotation speed while outputting a charge amount request of "UP" or "DOWN".

Further, after time t8, the engine control device 1 adjusts the intake amount of the engine 2 by controlling the bypass valve (an example of the adjusting unit). The bypass valve is a valve that opens and closes a bypass path that bypasses the intake path to the engine 2.

The engine control device 1 adjusts the intake amount with reference to the midpoint of the bypass valve. For example, the engine control device 1 adjusts the air density due to the temperature difference of the intake air by opening and closing the bypass valve. As a result, the amount of charge can be finely adjusted, so that the power generation efficiency can be further improved. Furthermore, by using the midpoint of the bypass valve as a reference, the increase or decrease in the intake air amount can be easily adjusted.

That is, the engine control device 1 adjusts the control for controlling the charge request amount using the engine 2 (first control) and the intake amount of the engine 2 as the control for adjusting the engine rotation speed to the target rotation speed. It is possible to perform control (second control) to control the possible adjustment unit (bypass valve), and when the fluctuation of the engine speed is large, the first control is performed without performing the second control. Take control.

Then, at time t9, when the remaining battery level becomes the power generation end threshold value TH2 or more, the battery monitor 6 outputs a “stop” power generation instruction to the power generation device 3 and the engine control device 1.

As a result, at time t9, the power generation device 3 stops the operating state of the inverter 32. Further, at time t9, the engine control device 1 stops the engine 2 and gradually reduces the rotation speed.

Note that FIG. 3 shows a case where the engine control device 1 controls the bypass valve after the rotation speed has converged in the control region, but bypasses before the rotation speed converges in the control region (before time t8). The valve may be controlled.

Next, the processing procedure of the processing executed by the engine control device 1 according to the embodiment will be described with reference to FIG. FIG. 4 is a flowchart showing a processing procedure of processing executed by the engine control device 1 according to the embodiment.

As shown in FIG. 4, first, the engine control device 1 determines whether or not the remaining battery level measured by the battery monitor 6 is equal to or less than the power generation start threshold value (S101).

Subsequently, the engine control device 1 drives the engine 2 by the motor generator (MG) 31 when the remaining battery level is equal to or lower than the power generation start threshold value (S101: Yes) (S102). When the remaining battery level exceeds the power generation start threshold value (S101: No), the engine control device 1 repeatedly executes step S101.

Subsequently, the engine control device 1 determines whether or not the rotation speed of the engine 2 has increased to a predetermined rotation speed corresponding to the control region due to the electric power drive (S103). The engine control device 1 executes step S102 when the rotation speed of the engine 2 has not risen to a predetermined rotation speed corresponding to the control region due to electric power drive (S103: No).

The engine control device 1 executes the fuel injection / ignition process of the engine 2 when the rotation speed of the engine 2 rises to a predetermined rotation speed corresponding to the control region (S103: Yes) by electric power drive (S104).

Subsequently, the engine control device 1 starts outputting a charge amount request to the power generation device 3 after the engine 2 is ignited (S105).

Subsequently, the engine control device 1 determines whether or not the engine speed is stable near the target speed (S106). When the engine speed is stable near the target speed (S106: Yes), the engine control device 1 controls the engine speed (second control) by the bypass valve opening degree (S107). On the other hand, when the engine speed is not stable near the target speed (S106: No), the engine control device 1 controls the engine speed by requesting the amount of charge (S108). Subsequently, the engine control device 1 determines whether or not the remaining battery level is equal to or higher than the power generation end threshold value (S109). When the remaining battery level is equal to or higher than the power generation end threshold value (S109: Yes), the engine control device 1 stops the fuel injection / ignition process (S110). Subsequently, the engine control device 1 stops the output of the charge amount request (S111), and ends the process.

On the other hand, when the remaining battery level is less than the power generation end threshold value (S109: No), the engine control device 1 executes step S106.

As described above, the engine control device 1 according to the embodiment includes a control unit 1a. The control unit 1a controls the engine 2 for generating electric power supplied to the motor 52, which is a power source of the vehicle. The engine 2 is not provided with a throttle valve whose opening degree changes according to the operating state of the accelerator pedal in the intake path, and the diameter of the intake path is the first operation in which the thermal efficiency of the engine 2 is equal to or higher than a predetermined value. The diameter is set to allow the amount of air in the region to pass through. Further, the control unit 1a starts at least one of the fuel injection control and the ignition control of the engine 2 when the engine speed becomes close to the value corresponding to the first operating region. As a result, the cost of the system can be reduced while achieving high power generation efficiency.

Further effects and variations can be easily derived by those skilled in the art. For this reason, the broader aspects of the invention are not limited to the particular details and representative embodiments expressed and described as described above. Therefore, various modifications can be made without departing from the spirit or scope of the general concept of the invention as defined by the appended claims and their equivalents.

1 Engine control device 1a Control unit 2 Engine 3 Power generation device 4 Battery 5 Drive device 6 Battery monitor 31 Motor generator 32,51 Inverter 52 Motor S control system

Claims (5)

Equipped with a control unit that controls the engine to generate electric power supplied to the motor that is the power source of the vehicle.
The engine is not provided with a throttle valve whose opening degree changes according to the operating state of the accelerator pedal in the intake path, and the diameter of the intake path is such that the thermal efficiency of the engine is equal to or higher than a predetermined value. It is set to a diameter that allows the amount of air that is the operating area to pass through.
The control unit
An engine control device, characterized in that at least one of fuel injection control and ignition control of the engine is started when the engine speed approaches a value corresponding to the first operating region. The control unit
When it becomes necessary to charge the battery, the engine is started by the motor, but when it is determined that the engine speed has reached the speed corresponding to the first operating region, the control state of the motor is set to the engine. The engine control device according to claim 1, further comprising switching from a driving state to a state in which the engine generates electricity. The control unit
As controls for adjusting the engine speed to a target speed, a first control for controlling a charge request amount using the engine and a second control for controlling an adjusting unit capable of adjusting the intake amount of the engine. And can be done,
The engine control device according to claim 1 or 2, wherein when the fluctuation of the engine speed is large, the first control is performed without performing the second control. The adjusting part
A bypass valve that opens and closes a bypass path that bypasses the intake path to the engine.
The control unit
The engine control device according to claim 3, wherein the intake amount is adjusted with reference to the midpoint of the bypass valve. Including a control process that controls the engine to generate electric power to be supplied to the motor that is the power source of the vehicle.
The engine is not provided with a throttle valve whose opening degree changes according to the operating state of the accelerator pedal in the intake path, and the diameter of the intake path is such that the thermal efficiency of the engine is equal to or higher than a predetermined value. It is set to a diameter that allows the amount of air that is the operating area to pass through.
The control step is
An engine control method characterized in that at least one of fuel injection control and ignition control of the engine is started when the engine speed becomes close to a value corresponding to the first operating region.

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