KR20160139650A - System and method for energy regeneration of mild hybrid electric vehicle - Google Patents

Abstract

The present invention provides a system and a method for energy regeneration of a mild hybrid electric vehicle, capable of controlling a speed of a hybrid starter-generator (HSG) in a regenerative braking and coasting mode to be in a speed zone with high charge efficiency in regardless of a speed of an engine, thereby maximizing charge efficiency and fuel efficiency. To achieve this, the system for energy regeneration of a mild hybrid electric vehicle comprises an HSG, a transmission, an engine clutch, a control part and a variable speed control device. The HSG is connected to transfer power to an engine. The transmission shifts a speed of power output from the engine to be transferred to a driving shaft. The engine clutch selectively connects and blocks power between the engine and the transmission. The control part outputs a control signal for controlling a speed of the HSG, which performs an electric power generation operation to charge a battery in a regenerative braking mode and a coasting mode, to be a speed obtained from an efficiency map. The variable speed control device controls the speed of the HSG by changing a speed of rotational force transferred from the driving shaft to the HSG in accordance with the control signal output by the control part.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an energy regeneration system for a mild hybrid vehicle,

The present invention relates to an energy regenerating apparatus and method for a hybrid vehicle, and more particularly, to an energy regenerating apparatus and method for controlling the speed of a hybrid starter-generator (HSG) in a regenerative braking and a costing mode, The present invention relates to an energy recovery device and method for a hybrid vehicle capable of maximizing charging efficiency and fuel efficiency.

The demand for environmentally friendly automobiles is increasing due to the demand for continuous improvement of fuel economy for automobiles and the strengthening of exhaust gas regulations of each country. Hybrid vehicles are being offered as a real alternative to this.

A typical hybrid vehicle is a vehicle that travels by using an engine and a motor as its driving source. It is an eco-friendly vehicle that can reduce exhaust gas and improve fuel economy by using electric energy together with fossil fuel energy for traveling.

Hybrid vehicles can be classified into Mild type and Hard type according to the usage ratio of the power source, and a mild type hybrid vehicle (Mild HEV) Type hard hybrid vehicle (Hard HEV) is a method in which the engine assists the torque while driving the motor as a basic drive source.

The power train configuration of a general mild hybrid vehicle (Mild HEV) is shown in FIG.

1, a power train configuration of a mild hybrid vehicle includes an engine serving as a driving source for driving a vehicle, a power transmission system connected to the engine via a belt, for starting the engine or receiving power from the engine. A hybrid starter and generator (HSG) that performs power transmission, a transmission that shifts the power output from the engine to transmit the power to the drive shaft, and an engine clutch that selectively connects or disconnects power between the engine and the transmission do.

In this configuration, the hybrid starter-generator (hereinafter referred to as HSG) serves not only as a starter for starting the engine but also as a generator for generating the battery with the rotational force transmitted from the engine at the time of vehicle braking or running, When the vehicle is accelerated, it is also used as a motor that assists the engine output (torque) as an auxiliary driving source for driving the vehicle.

In such a mild hybrid vehicle, there is no EV (Electric Vehicle) mode that uses only the power of the motor during departure or traveling, and the regenerative braking Regenerative Braking "mode and a" Coasting "mode in which the engine is turned off and the engine clutch is disengaged when the vehicle is traveling in the other direction.

Generally, the regenerative braking mode is executed when the driver releases his / her foot from the accelerator pedal (Accel Pedal Off) and the brake pedal is depressed (Brake Pedal On). In the regenerative braking mode, State, the rotational force of the drive wheel and the drive shaft is transmitted to the engine through the transmission, so that the engine clutch is kept continuously connected during the inertial travel of the vehicle.

At this time, regenerative braking is performed in which the frictional resistance of the engine acts and the HSG receives the rotational force of the engine via the belt and performs power generation operation. In addition to the frictional resistance of the engine, The electric braking force (regenerative braking force) generated by the HSG acts on the vehicle, so that the vehicle decelerates. Further, the electric energy generated by the development of the HSG is stored in the battery.

Such a regenerative braking mode is intended to braking the vehicle, so it reduces the moving distance of the vehicle by decelerating the vehicle, but improves the fuel economy by recovering the energy of the vehicle as electric energy.

Needless to say, of the driver's required braking force, only the regenerative braking force is satisfied by using the frictional braking force (hydraulic braking force) of the braking device (e.g., hydraulic brake) mounted on the wheel.

In addition, when the driver releases his / her foot from both the accelerator pedal and the brake pedal (Accel Pedal Off, Brake Pedal Off), the costing mode is executed. In the costing mode, the engine is turned off, The engine clutch is disengaged and the connection between the engine and the transmission is released, so that the frictional resistance of the engine is not transmitted to the vehicle.

Since the frictional resistance of the engine obstructing the running of the vehicle is not transmitted, the moving distance of the vehicle can be extended. However, since the driving force for driving the HSG, i.e., the rotational force transmitted from the engine through the belt, It can not be done.

On the other hand, in the hybrid vehicle, the HSG is connected to the shaft of the engine and the belt, and the speed (revolution) of the HSG is determined according to the speed (revolution) of the engine.

Therefore, in the conventional energy regeneration process, it is not possible to regenerate the energy through the HSG in the costing mode, and in the regenerative braking mode, the speed of the HSG can not be controlled in the high speed region regardless of the speed of the engine. Efficiency) can not be maximized.

Accordingly, the present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide a hybrid vehicle which can control the speed of the HSG in the regenerative braking and the costing mode, And to provide an energy recovery device and method of a hybrid vehicle that can maximize the improvement.

In addition, it is possible to minimize the loss of moving distance of the vehicle while the vehicle is traveling in another running mode, and to recover the energy by controlling the driving of the HSG in a state in which the battery can be charged, And an object of the present invention is to provide an energy regenerating apparatus and method for an automobile.

According to an aspect of the present invention, there is provided a hybrid starter-generator connected to an engine in a power transmitting manner, A transmission for shifting a power output from the engine and transmitting the power to a drive shaft; An engine clutch for selectively connecting or disconnecting power between the engine and the transmission; A control unit for outputting a control signal for controlling the speed of the hybrid starter-generator which is operated to generate power during the regenerative braking mode and the costing mode of the vehicle to charge the battery at a speed obtained from the efficiency map; And a variable speed control device for controlling a speed of a hybrid starter-generator by varying a speed of a rotational force transmitted from a drive shaft to the hybrid starter-generator according to a control signal output from the control part. to provide.

According to another aspect of the present invention, there is provided a hybrid starter-generator, which operates when a control unit enters a regenerative braking mode or a costing mode, And outputting a control signal for controlling the control signal; And controlling the speed of the hybrid starter-generator by varying the speed of the rotational force transmitted from the drive shaft to the hybrid starter-generator according to the control signal output from the control unit. to provide.

Thus, according to the energy recovery apparatus and method of the hybrid vehicle according to the present invention, it is possible to maximize the charging efficiency and the fuel efficiency improvement by controlling the speed of the HSG in the regenerative braking mode to the speed region where the charging efficiency is high regardless of the speed of the engine do.

Also, in the costing mode of the hybrid vehicle, the battery can be charged (energy regeneration) by driving the HSG in a region where the charging efficiency is high according to the battery charging state while minimizing the travel distance loss, thereby improving the fuel efficiency of the vehicle do.

1 is a diagram showing a power train configuration of a general mild hybrid vehicle.
2 is a schematic diagram showing a configuration of a hybrid system including an energy recovery device according to an embodiment of the present invention.
3 is a schematic view showing a configuration of a hybrid system including an energy recovery device according to another embodiment of the present invention.
4 is a flowchart showing an energy recovery method according to the present invention.
FIG. 5 is a diagram illustrating an efficiency map showing a charging efficiency according to an operation region in the energy recovery method according to the present invention.
FIG. 6 is a view for explaining an operation effect of the energy recovery method according to the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings, which will be readily apparent to those skilled in the art to which the present invention pertains.

The present invention maximizes the charging efficiency and fuel efficiency by controlling the speed of the hybrid starter-generator (hereinafter referred to as HSG) in the regenerative braking and the costing mode in a high-charge-speed region regardless of the engine speed And to provide an energy regenerating apparatus and method for a hybrid vehicle that can be used in a hybrid vehicle.

FIG. 2 is a schematic view showing a configuration of a mild hybrid system including an energy regenerating device according to an embodiment of the present invention, and FIG. 3 is a view showing a configuration of a hybrid system including an energy regenerating device according to another embodiment of the present invention Fig.

As shown in the figure, the construction of the mild hybrid system includes an engine 1 serving as a drive source for driving a vehicle, a power transmission system connected to the engine 1 via a belt 3, A transmission 4 for transmitting the power output from the engine 1 to a drive shaft and a power selector 4 for selectively transmitting power between the engine 1 and the transmission 4, (Not shown).

In this configuration, the HSG 2 serves not only as a starter for starting the engine 1, but also as a generator for generating electric power from the engine 1 and charging the battery (not shown) When the vehicle is accelerating, it is also used as a motor that assists the engine output (torque) as an auxiliary driving source for running.

Further, in the regenerative braking mode and the costing mode, the HSG 2 is energized by the rotational force transmitted from the drive shaft in a state where power is disconnected from the engine 1, thereby charging the battery.

The configuration of the above-described mild hybrid system allows the HSG 2 to assist the engine output (torque) at the same time as the engine 1 is driven when the vehicle is running, The HEV mode can be implemented and there is no difference in the control of the engine stand-alone mode and the HEV mode as compared with a conventional hybrid vehicle.

The rotation axis of the HSG 2 connected to the engine 1 through the rotary shaft integrally connected to the rotor of the HSG 2, that is, the belt 3 is connected to the input shaft 3 of the transmission 4, (The axis through which the engine driving force is input via the engine clutch).

In addition, a variable speed control device capable of controlling the speed of the HSG by selectively transmitting the rotational force during the vehicle inertia traveling from the drive shaft of the vehicle to the HSG 2 and varying the speed of the rotational force when transmitting the rotational force to the HSG Respectively.

In the present invention, the speed of the HSG 2 is shifted to a region having a high charging efficiency when the energy is regenerated by using a variable speed control device to increase the energy to be regenerated.

At this time, the variable speed control device may be configured to change the rotational speed transmitted from the drive shaft of the vehicle to the HSG 2 or the rotational speed transmitted from the drive shaft to the HSG 2 through the transmission 4 have.

In a preferred embodiment, as shown in Fig. 2, the variable speed control device is operable to transmit power to the engine 1 via a rotary shaft integrally connected to a rotor of the HSG 2, that is, a belt 3 A continuously variable transmission CVT (CVT) 4, which connects the rotational axis of the connected HSG 2 to the input shaft of the transmission 4 in a powertransmitting manner, and which can vary the gear ratio between the HSG 2 and the transmission 4, Continuously Variable Transmission (6).

At this time, the HSG 2 is provided with a clutch means (not shown) between the pulley of the HSG to which the belt 3 is coupled and the rotation axis of the HSG so that the power can be selectively connected or disconnected from the engine 1 And this clutch means can be similar to an electromagnetic clutch, such as a magnetic clutch, as in an air-conditioner compressor.

Since the adoption of such a magnetic clutch is applied between the rotary shaft of the compressor and the pulley in the air-conditioner compressor, the drawings and further detailed description thereof will be omitted in this specification.

The magnetic clutch may be controlled by a transmission control unit (TCU) or a controller (HCU, ECU, MCU, etc.) mounted on the vehicle.

3, the variable speed control device applies the continuously variable transmission 4a as a transmission for shifting the power output through the engine 1 to the drive shaft, and the HSG 2, And the input shaft of the continuously variable transmission 4a may be connected to each other via a separate clutch 7.

The clutch 7 is disengaged when the power of the engine 1 is transmitted to the transmission 4 or when the HSG 2 assists the output of the engine 1 and only in the regenerative braking mode or the costing mode, .

A continuously variable transmission 6 interposed between the HSG 2 and the transmission 4 in the configuration of Fig. 2 and a clutch 7 and a continuously variable transmission 4a interposed between the HSG 2 and the drive shaft in the configuration of Fig. All of which can be configured to drive-control the vehicle speed change controller.

At this time, as will be described later, a hybrid control unit (HCU), which is a top-level controller for determining the running mode of the vehicle, an engine control unit (ECU) for controlling the engine 1, a shift control unit (TCU) When a running mode is determined under the coordinated control between a battery management system (BMS) for collecting battery status information and a motor control unit (MCU) for controlling the driving of the HSG 2, It is possible that each component can be controlled.

Of course, one integrated control unit may be configured to control the operation of each component according to the running mode.

FIG. 4 is a flowchart showing an energy regeneration method according to the present invention, and FIG. 5 is a diagram illustrating an efficiency map showing a charging efficiency according to an operation region in the energy regeneration method according to the present invention.

6 is a diagram for explaining the operation and effect of the energy recovery method according to the present invention.

Hereinafter, an energy regeneration method according to the present invention will be described.

First, when the driver depresses the brake pedal and satisfies the normal regenerative braking entry condition, the regenerative braking mode is entered to regenerate energy using the HSG 2 and charge the battery. At this time, the speed of the HSG 2 (The number of revolutions) to a region where charging efficiency is high during regenerative braking, and a variable speed control device is used to control the speed of the HSG 2.

At this time, an efficiency map as shown in Fig. 5 can be used, and at the regenerative braking, the engine 1 is brought into a fuel cut state by the engine controller (control unit) in a state where the engine clutch 5 is joined, The gear ratio of the continuously variable transmission 6 is changed to a state in which the transmission mechanism (control section) separates the clutch means (magnetic clutch) built in the HSG 2 and cuts off the power between the engine 1 and the HSG 2, To move the speed of the HSG 2 to a region where the charging efficiency is high.

In the embodiment of Fig. 3, the transmission controller (control section) joins the clutch 7 between the HSG 2 and the continuously variable transmission 4a, and the clutch 7 of the continuously variable transmission 4a disposed between the engine 1 and the drive shaft And controls the gear ratio to move the speed of the HSG 2 to a region where the charging efficiency is high.

When the driver does not depress both of the accelerator pedal and the brake pedal, the mode enters the costing mode instead of the regenerative braking mode. In the costing mode, the shift controller (control unit) releases the engagement of the engine clutch 5, The engine controller (control section) turns off the engine 1. [

In addition, in this state, it is checked whether the battery is chargeable from the battery charging state received from the battery controller. If the battery is chargeable, the energy regeneration using the HSG 2 and the battery charging are performed Control is performed.

2, the transmission controller (control section) separates the clutch means (magnetic clutch) incorporated in the HSG 2 and disconnects the power between the engine 1 and the HSG 2 to stop the continuously variable transmission 6 3, the speed change controller (control section) controls the clutch 7 between the HSG 2 and the continuously variable transmission 4a by controlling the gear ratio of the HSG 2 to the high- And also controls the gear ratio of the continuously variable transmission 4a disposed between the engine 1 and the drive shaft to move the speed of the HSG 2 to the high charging efficiency range.

On the other hand, if the battery can not be charged, energy regeneration using the HSG (2) is not performed.

Of course, in the case of the embodiment of FIG. 2, in the HEV mode in which the engine 1 alone mode or the HSG 2 assists the output of the engine 1, driving force generation and transmission for driving the vehicle can be performed. The state of engagement of the engine clutch 5 in the embodiment of Fig. 3 and the engagement state of the HSG 2 and the continuously variable transmission 4a (i.e., the engagement state of the magnetic clutch incorporated in the HSG 2 The engine 1 is driven or the engine 1 and the HSG 2 are driven together.

The regenerative torque (charge torque, power generation torque) control of the HSG 2 in the regenerative braking mode and the costing mode can be set so that the motor controller takes charge in the normal case as well.

As described above, in the present invention, the speed of the HSG 2 is controlled in the speed range in which the charging efficiency is high regardless of the speed of the engine 1 in the regenerative braking mode, thereby maximizing the charging efficiency and the fuel efficiency improvement.

Also, in the costing mode of the hybrid vehicle, as shown in FIG. 6, the battery can be charged (energy regeneration) by driving the HSG 2 in the region where the charging efficiency is high according to the battery charging state while minimizing the loss of travel distance The fuel economy of the vehicle can be improved.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the scope of the present invention is not limited to the disclosed exemplary embodiments. Forms are also included within the scope of the present invention.

1: Engine 2: HSG
3: Belt 4: Transmission
4a: continuously variable transmission (CVT) 5: engine clutch
6: continuously variable transmission (CVT) 7: clutch

Claims (10)

A hybrid starter-generator coupled to the engine for power transmission;
A transmission for shifting a power output from the engine and transmitting the power to a drive shaft;
An engine clutch for selectively connecting or disconnecting power between the engine and the transmission;
A control unit for outputting a control signal for controlling the speed of the hybrid starter-generator which is operated to generate power during the regenerative braking mode and the costing mode of the vehicle to charge the battery at a speed obtained from the efficiency map; And
And a variable speed control device for controlling a speed of the hybrid starter-generator by varying a speed of a rotational force transmitted from the drive shaft to the hybrid starter-generator according to a control signal output from the control part.
The method according to claim 1,
The variable speed control device includes:
The hybrid starter-generator shaft is connected to the input shaft of the transmission for power transmission,
A continuously variable transmission interposed between the rotary shaft of the hybrid starter-generator and the input shaft of the transmission so as to vary the gear ratio to vary the rotational speed; And
And a clutch means interposed between the rotating shaft and a pulley connected to the engine by a belt so that power can be selectively connected or disconnected from the engine in the hybrid starter-generator. Energy recovery device of a hybrid vehicle.
The method of claim 2,
Wherein the clutch means is operated to shut off the power between the pulley and the rotary shaft by a control signal outputted from the control unit in the regenerative braking mode and the costing mode of the vehicle.
The method according to claim 1,
The variable speed control device includes:
The hybrid starter-generator shaft is connected to the input shaft of the transmission for power transmission,
And a continuously variable transmission for varying the speed of the rotational force by varying the gear ratio as the transmission,
And a clutch for connecting or disconnecting power between the rotary shaft of the hybrid starter-generator and the input shaft of the continuously variable transmission.
The method of claim 4,
Wherein the clutch of the variable speed control device is operable to connect power between a rotation shaft of the hybrid starter-generator and an input shaft of the continuously variable transmission by a control signal output from the control unit in a regenerative braking mode and a costing mode of the vehicle. Energy recovery device of a hybrid vehicle.
Outputting a control signal for controlling the speed of the hybrid starter-generator, which operates when the control unit enters the regenerative braking mode or the costing mode, to charge the battery at a speed obtained from the efficiency map; And
And controlling the speed of the hybrid starter-generator by varying the speed of the rotational force transmitted from the drive shaft to the hybrid starter-generator according to the control signal output from the control unit.
The method of claim 6,
The variable speed control device includes:
The hybrid starter-generator shaft is connected to the input shaft of the transmission for power transmission,
A continuously variable transmission interposed between the rotary shaft of the hybrid starter-generator and the input shaft of the transmission so as to vary the gear ratio to vary the rotational speed; And
And a clutch means interposed between the rotating shaft and a pulley connected to the engine by a belt so that power can be selectively connected or disconnected from the engine in the hybrid starter-generator. Energy recovery method of hybrid vehicle.
The method of claim 7,
Wherein the clutch means is actuated to interrupt power between the pulley and the rotary shaft by a control signal output from the control unit in the regenerative braking mode and the costing mode of the vehicle.
The method of claim 6,
The variable speed control device includes:
The hybrid starter-generator shaft is connected to the input shaft of the transmission for power transmission,
And a continuously variable transmission for varying the speed of the rotational force by varying the gear ratio as the transmission,
And a clutch for connecting or disconnecting power between the rotary shaft of the hybrid starter-generator and the input shaft of the continuously variable transmission.
The method of claim 9,
Wherein the clutch of the variable speed control device is operable to connect power between a rotation shaft of the hybrid starter-generator and an input shaft of the continuously variable transmission by a control signal output from the control unit in a regenerative braking mode and a costing mode of the vehicle. Energy recovery method of hybrid vehicle.

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