KR101766092B1

KR101766092B1 - Control method of hybrid electric vehicle

Info

Publication number: KR101766092B1
Application number: KR1020150178102A
Authority: KR
Inventors: 이수방; 김상준
Original assignee: 현대자동차주식회사
Priority date: 2015-12-14
Filing date: 2015-12-14
Publication date: 2017-08-07
Also published as: KR20170070508A

Abstract

The present invention relates to a control method for enhancing the fuel economy of a hybrid vehicle for enhancing fuel economy by enlarging the application of a slow torque path mode which is advantageous for enhancing the engine efficiency. More specifically, In a slow torque path mode in which the engine torque is controlled based on the amount of air sucked into the engine for efficient control of the engine, And an object of the present invention is to provide a control method for improving the fuel economy of a hybrid vehicle that can increase engine efficiency and fuel economy by controlling engine torque.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a control method for a hybrid vehicle,

The present invention relates to a control method for improving the fuel economy of a hybrid vehicle, and more particularly, to a control method for improving the fuel economy of a hybrid vehicle for enhancing fuel economy by enlarging a slow torque path mode, .

Generally, a hybrid vehicle is a vehicle that uses an engine and a motor as a power source, and transmits the engine or motor power separately to the traveling wheel or transmits the engine and the motor power to the traveling wheel together.

The hybrid vehicle using the power of the engine and the driving motor performs the engine torque control based on the ignition timing in consideration of the torque reactivity of the engine in order to efficiently control the engine torque. In the case of controlling the engine torque based on the ignition timing There is a problem that the ignition angle change becomes relatively frequent due to always waiting in the fast torque path mode for quickly responding to the torque fluctuation of the engine, and the engine efficiency is lowered.

The present invention relates to an engine control system for controlling an engine torque in a fast torque path mode so as to be able to quickly respond to an engine torque command and to control the engine torque based on an amount of air sucked into the engine for efficient control of the engine, the present invention provides a control method for improving the fuel efficiency of a hybrid vehicle in which the engine torque can be controlled in a slow torque path mode under the condition that the engine can enter the torque path mode to increase the engine efficiency and improve the fuel efficiency.

Therefore, the present invention provides a control method for improving the fuel economy of a hybrid vehicle, characterized in that the torque path mode for engine torque control is determined based on whether or not the vehicle is shifting, whether the vehicle is traveling in another direction, and whether or not the engine clutch is engaged.

Specifically, when the vehicle is not shifting and the engine clutch is in the engaged state, the torque path mode of the engine is determined as the slow torque path mode in both of the case of the non-selected running state and the non-selected running state,

When the vehicle is in a shifting state and not in a shifting state for braking and the engine clutch is in the engaged state and is not in the other traveling state, the torque path mode of the engine is determined as the slow torque path mode,

When the vehicle is in the shifting state and not in the shifting state for braking, and the engine clutch is in the engaged state and in the other traveling state, the torque path mode of the engine is determined as the fast torque path mode.

The control method is applied to a hybrid vehicle in which an engine clutch is installed between an engine and a motor, and a battery, which is a power source of a motor, can be charged through an HSG (Hybrid Starter Generator) attached to the engine during traveling It is possible.

According to the control method of the hybrid vehicle according to the present invention, the slow torque path mode which is advantageous for increasing the engine efficiency although the followability to the engine torque command is lower than the fast torque path mode is applied within a range that does not hinder the operability, So that the fuel efficiency can be improved.

1 is an exemplary diagram showing a power transmission system of a hybrid vehicle to which a control method for a hybrid vehicle according to the present invention is applicable;
2 is an exemplary diagram showing an engine torque command and an actual engine torque when the engine torque is controlled in the slow torque path mode
3 is a flowchart for explaining a control method of a hybrid vehicle according to the present invention.

First, to facilitate understanding of the present invention, a structure of a power transmission system for a hybrid vehicle will be described.

A hybrid vehicle is a vehicle that uses an engine and a motor as power sources. The hybrid vehicle is equipped with a power transmission system that transfers engine or motor power to the traveling wheel, or transmits the engine and motor power to the traveling wheel together.

An example of a hybrid vehicle power transmission system is arranged between an engine 10 and a drive motor 12 arranged in series with each other, an engine 10, and a drive motor 12, A transmission 14 for shifting and outputting a drive motor or a drive power of the engine to the traveling wheels and a crank pulley 14 connected to the crank pulley of the engine so as to transmit power, A hybrid starter generator (HSG) 16, which is a kind of motor for generating electric power for power generation, and a battery 20 (not shown) connected to the inverter so as to provide power to the inverter 18 and the drive motor 12 for motor control and power generation control And the like.

This hybrid vehicle power transmission system is a type in which a motor is attached to an automatic transmission and is called a TMED (Transmission Mounted Electric Device) system. It is an EV (electric vehicle) mode which is a pure electric vehicle mode using only the driving motor power, A hybrid electric vehicle (HEV) mode in which a driving motor is used as an auxiliary power while being powered, a regenerative braking (RB) mode in which the braking and inertial energy of the vehicle is recovered through power generation at the time of braking or inertia, Regenerative Braking) mode.

The hybrid vehicle is provided with a controller for each device constituting the system. The hybrid vehicle includes a hybrid control unit (HCU) for controlling the entirety of the hybrid vehicle, an engine controller (ECU) Engine Control Unit (MCU) that controls the overall operation of the drive motor, Transmission Control Unit (TCU) that controls the transmission, Battery Controller (BMS) that monitors and manages the battery status Management System).

In the present invention, in order to apply the slow torque pass mode which is advantageous for increasing the engine efficiency although the tracking accuracy to the engine torque command is lower than the fast torque path mode within a range that does not hinder the drivability, the hybrid controller becomes a control subject By determining the torque path mode of the engine, it is possible to increase the engine efficiency and improve the fuel economy.

The fast torque-pass mode is a torque-path mode for controlling the engine torque based on the ignition timing of the engine. The torque-path mode follows the engine torque command on the basis of the ignition timing to relatively improve the torque accuracy. Relatively frequent ignition angle changes occur in the process corresponding to the torque fluctuation.

The slow torque path mode is a torque path mode for controlling the engine torque based on the amount of air sucked into the engine for combustion, and the follow-up to the engine torque command is relatively delayed due to the air flowability or the like sucked into the engine, While the ignition angle change is relatively reduced in the process corresponding to the torque fluctuation, which is advantageous to increase the engine efficiency.

FIG. 2 attached is an example of an engine torque command and an actual engine torque when the engine torque is controlled in the slow torque path mode.

2, when the engine torque is controlled in the slow torque path mode, the actual engine torque does not accurately follow the engine torque command. Therefore, when shifting is performed, the torque accuracy is deteriorated and the shift quality is deteriorated. Even when the clutch is engaged and disengaged, the actual engine torque is outputted as large or small as compared with the engine torque command. Therefore, when the engine clutch is engaged, the driver's torque is unsatisfactory or when the engine clutch is released, Thereby adversely affecting fuel economy and driving performance.

Therefore, in the present invention, the hybrid controller determines the entry and release control conditions of the slow torque path mode within a range in which the operability is not hindered, determines the torque path mode of the engine as the slow torque path mode only when the entry condition is satisfied, In the pass mode, the engine torque is controlled so that the same level of driving performance can be secured even when the torque accuracy is lowered.

According to the present invention, in order to broadly apply the slow torque path mode in the hybrid vehicle of the TMED type, it is necessary to determine the torque path mode of the engine by distinguishing the case of shifting and the case of not shifting, (The vehicle before the present invention is applied).

Accordingly, the torque path mode of the engine is determined on the basis of whether or not the engine clutch is engaged (or locked up) and whether the vehicle is running another way, in addition to whether or not the vehicle is shifting.

In other words, it is determined whether or not the vehicle is shifting, the contact and release states of the engine clutch are determined, and the hybrid controller determines the torque path mode of the engine as the slow torque path mode or the fast torque path mode, And the engine controller that has received the torque path mode information determined in the hybrid controller performs engine torque control based on the received information.

When the engine torque is controlled in this way, the range of application of the slow torque path mode during the shift can be expanded, and the application range of the slow torque path mode can be extended even when the engine clutch is engaged and released.

In addition, in order to maintain the engagement of the engine clutch in order to accelerate the acceleration in the sport mode and the very low battery SOC (State Of Charge) in which the fluctuation of the engine torque command is large during the driver mode and the regenerative braking Or when the regenerative braking is performed in a situation where the shifting is performed during the regenerative braking or when the torque accuracy with respect to the engine torque command is decreased, the drivability deteriorates. Thus, in the state where the engine clutch is engaged It is advantageous not to use the slow torque path mode.

FIG. 3 is a flow chart for explaining a method of controlling entry of a slow torque path mode of a hybrid vehicle according to the present invention.

Referring to FIG. 3, first, it is determined whether or not a shift is being made for vehicle braking.

In the fast torque path mode, the engine clutch connected between the engine and the motor is released, and the torque transmitted from the motor to the engine is '0'. In the slow torque path mode, however, Can not be released and the joint state is maintained. In this case, the motor torque greater than '0' is transmitted to the engine and the braking linearity is broken.

In addition, in the case of braking by stepping on the brake pedal, the actual engine torque must be accurately tracked to the engine torque command in order to secure the running stability.

Therefore, in the case of shifting for vehicle braking, the torque path mode of the engine is determined as the fast torque path mode regardless of whether or not the engine clutch is engaged, that is, both when the engine clutch is in the engaged state and in the released state.

When the engine is not shifting for braking the vehicle, if the engine clutch is in the released state, the torque path mode of the engine is determined as the fast torque path mode so that the engine torque is controlled to the fast torque path mode.

According to the present invention, in the hybrid controller, the torque path mode of the engine is basically maintained in the fast torque path mode, and the vehicle enters the slow torque path mode on the basis of whether or not the vehicle is engaged, whether the engine clutch is engaged, The torque path mode of the engine is determined to be the slow torque path mode only when the condition is satisfied.

However, when the engine clutch is in the unjoined state, the engine controller temporarily determines the torque path mode of the engine, so that the hybrid controller decides to maintain the fast torque path mode as the basic torque path mode.

Next, in the case where the engine clutch is in the engaged state and the gear position is not changed, the torque path mode of the engine is switched to the slow torque path mode .

When the engine clutch is in the released state or in the shifting state, the behavior of the hydraulic pressure is changed in the power transmission system (specifically, the power transmission apparatus including the engine clutch and the transmission that transmit the generated power of the engine) The shift quality is deteriorated during shifting or the drivability is deteriorated in releasing the engine clutch if a transient situation in which an excessive change in engine torque occurs is engaged.

However, when the engine clutch is in the engaged state and not in the shifting state, the above-described oil pressure fluctuation does not occur. Therefore, the torque path mode of the engine can be determined regardless of whether the engine torque fluctuates, There is no adverse effect on the driving performance, so that the slow torque path mode can be used as the torque path mode of the engine.

Subsequently, if the engine is in the shifting state in which the gear position is changed but not in the shift for vehicle braking, and the engine clutch is in the engaged state and not in the other running state, the torque path mode of the engine is determined as the slow torque path mode.

If the vehicle is in the shifting state but is not shifting for braking, When the vehicle is not in a running state, the vehicle is driven in accordance with the driver's request (for example, And so on). Therefore, even if the engine torque fluctuates, the transient situation in which excessive fluctuations do not occur does not deteriorate the drivability even if the engine torque is controlled in the slow torque pass mode.

More specifically, even if the engine torque is controlled in the slow torque path mode, the driving performance is not degraded even if the actual engine torque does not follow the engine torque command more or less accurately. Therefore, It is possible to use the slow torque path mode as the torque path mode of the engine if the engine clutch is in the engaged state and not in the other running state,

In addition, while the engine is in a shifting state in which the gear position is changed but not in the shifting state for braking the vehicle, the engine clutch is in the engaged state and the accelerator pedal is turned off to stop the engine drive When the vehicle is traveling in the other running state, the torque path mode of the engine is determined as the fast torque path mode.

The engine torque is excessively varied in the transient state during the other traveling, so that it is possible to further change the gear position in accordance with the decrease of the vehicle speed. When the engine torque is controlled in the slow torque path mode, the actual engine torque accurately follows the engine torque command It is preferable to determine the torque path mode of the engine as the fast torque path mode because the torque accuracy is deteriorated and the shift quality is deteriorated when the gear position is changed.

In addition, in the TMED type hybrid vehicle, battery charging using HSG (Hybrid Starter Generator) attached to the engine is performed by the power transmitted from the wheels through the engine clutch during the above-mentioned two-way traveling, It is desirable to control the engine torque in the fast torque path mode so that the engine torque can be accurately followed.

As described above, in the present invention, when it is necessary to accurately follow the torque command to the engine torque command, it is determined that the engine torque can be controlled in the fast torque path mode, and in other cases, the engine torque can be controlled in the slow torque path mode , It is possible to secure the operability even if the engine torque is controlled by the slow torque path mode in which the torque follow-up accuracy with respect to the engine torque command is lowered. Further, the application range of the slow torque path mode is expanded to improve the fuel efficiency by increasing the engine efficiency .

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. Modifications are also included in the scope of the present invention.

Claims

Determines a torque path mode for engine torque control based on a result of determining whether or not the vehicle is shifting, whether the vehicle is traveling in another direction, and whether or not the engine clutch is engaged, and enters a slow torque path mode for controlling engine torque based on the intake air amount of the engine And the engine torque can be controlled in a slow torque pass mode under a possible condition.

The method according to claim 1,
The torque path mode of the engine is determined to be the slow torque path mode in both of the case where the vehicle is in the other traveling state and the case where the vehicle is in the other traveling state when the vehicle is not shifting and the engine clutch is in the engaged state. Control method.

The method according to claim 1,
Wherein the torque path mode of the engine is determined as the slow torque path mode when the vehicle is in the shifting state and the engine clutch is in the engaged state and not in the other running state.

The method according to claim 1,
Wherein the torque path mode of the engine is determined as the fast torque path mode when the vehicle is in the shifting state and the engine clutch is in the engaged state and in the other running state.

The method according to claim 3 or 4,
Wherein the vehicle is in a shifting state and is not in a shifting state for braking.

The method according to claim 1,
Wherein the hybrid vehicle is a hybrid vehicle in which an engine clutch is installed between an engine and a motor, and a battery, which is a power source of a motor, is able to be charged through an HSG (Hybrid Starter Generator) A control method for improving fuel economy of a vehicle.