KR102699147B1 - Hybrid vehicle and method of driving mode control for the same - Google Patents

Abstract

The present invention relates to a hybrid vehicle capable of engine control considering the convenience of passengers when the vehicle is stopped, and a mode control method therefor. The control method of a hybrid vehicle according to one embodiment of the present invention may include: a step of calculating a remaining engine start time according to an electric load when the vehicle is stopped; a step of first comparing a target rest time with the remaining engine start time; a step of charging a battery using the power of the engine if the target rest time is longer as a result of the first comparison; a step of secondly comparing the updated remaining engine start time according to the charging of the battery with the remaining target rest time; and a step of stopping the start of the engine if the remaining target rest time is shorter than the updated remaining engine start time as a result of the second comparison.

Description

HYBRID VEHICLE AND METHOD OF DRIVING MODE CONTROL FOR THE SAME

The present invention relates to a hybrid vehicle capable of controlling an engine considering the convenience of passengers when the vehicle is stopped, and a mode control method therefor.

Hybrid vehicles (HEV: Hybrid Electric Vehicle) are generally vehicles that use two power sources together, and the two power sources are mainly an engine and an electric motor. These hybrid vehicles are not only superior in fuel efficiency and power performance compared to vehicles equipped with only internal combustion engines, but are also advantageous in reducing exhaust gas, so they are being developed a lot recently.

These hybrid vehicles can operate in two driving modes, depending on the powertrain. One of them is an electric vehicle (EV) mode that runs solely on electric motors, and the other is a hybrid electric vehicle (HEV) mode that runs both the electric motor and the engine. Hybrid vehicles switch between the two modes depending on driving conditions.

Switching between these driving modes is usually done to maximize fuel economy or driving efficiency, depending on the efficiency characteristics of the powertrain.

First, the hybrid vehicle structure is explained with reference to Fig. 1. Fig. 1 shows an example of the power train structure of a typical parallel hybrid vehicle.

Referring to FIG. 1, a power train of a hybrid vehicle is illustrated that employs a parallel type hybrid system in which an electric motor (or drive motor, 140) and an engine clutch (EC: Engine Clutch, 130) are mounted between an internal combustion engine (ICE, 110) and a transmission (150).

In these vehicles, when the driver steps on the accelerator after starting the engine, the engine clutch (130) is opened and the motor (140) is driven first using the power of the battery, and the power of the motor moves the wheels through the transmission (150) and the final drive (FD: Final Drive, 160) (i.e., EV mode). When the vehicle gradually accelerates and a greater driving force is required, the auxiliary motor (or, starter-generator motor, 120) may be operated to drive the engine (110).

Accordingly, when the rotation speeds of the engine (110) and the motor (140) become the same, the engine clutch (130) is engaged so that the engine (110) and the motor (140) drive the vehicle together, or the engine (110) drives the vehicle (i.e., transition from EV mode to HEV mode). When a preset engine-off condition, such as when the vehicle decelerates, is satisfied, the engine clutch (130) is opened and the engine (110) is stopped (i.e., transition from HEV mode to EV mode). In addition, in a hybrid vehicle, the driving force of the wheels can be converted into electric energy during braking to charge the battery, which is called braking energy regeneration, or regenerative braking.

The starter generator motor (120) functions as a starter motor when the engine is started, and operates as a generator when recovering the rotational energy of the engine after the engine is started or when the engine is turned off. Therefore, it can be called a “hybrid starter generator (HSG)” and, in some cases, it can also be called an “auxiliary motor.”

Based on the above-described structure, the driving modes of hybrid vehicles are described in more detail as follows.

EV mode is mainly applied in situations where the speed and required torque are low, and the engine clutch (130) is opened and only the motor (140) is used as a power source to transmit torque to the wheels.

The HEV mode is mainly applied in situations where high speed and high torque requirements are required, and uses an engine (110) and a motor (140) as power sources. This mode can be further divided into an HEV series mode and an HEV parallel mode. In the HEV series mode, the engine clutch (130) is opened, the power of the engine (110) is used for power generation in the HSG (120), and only the motor (140) directly generates driving force. In contrast, in the HEV parallel mode, the engine clutch (130) is locked, and the driving power of the engine (110) and the driving power of the motor (140) are transmitted to the wheels together.

However, when the occupant of a hybrid vehicle wants to stop for a while and take a rest, it is common for the vehicle to operate in EV mode since it is stopped. In EV mode, since the engine is not started, there is an advantage in that resting is possible in a state with relatively less vibration and noise compared to when the engine is started. However, if this state continues for a certain period of time, charging is performed by switching to HEV series mode to prevent a decrease in the battery's state of charge (SOC: State Of Charge) due to the vehicle's electrical load. This situation is explained with reference to Fig. 2.

Figure 2 shows an example of how engine starting is performed while the vehicle is stopped in a typical hybrid vehicle.

Referring to Fig. 2, if the vehicle is stopped while maintaining the EV mode, the SOC of the battery decreases due to the electrical load, and when it reaches the SOC (i.e., engine On standard), which is the transition threshold for the HEV mode, charging is performed in the HEV series mode. When the SOC reaches a certain level again (i.e., engine Off standard) as a result of the charging, it switches to the EV mode again, but the SOC decreases again due to the electrical load. Eventually, as the vehicle is stopped, the engine starts and stops periodically.

At this time, there is a problem that the driver is disturbed from resting, such as being surprised by a sudden engine start while resting, because the driver cannot know the engine start time. Therefore, a technology is needed to improve the effects of noise and vibration caused by engine intervention in hybrid vehicles.

The present invention provides a hybrid vehicle capable of controlling engine start for driver rest in a stationary state and a control method thereof.

In particular, the present invention provides a hybrid vehicle and a control method thereof capable of preventing repeated engine starting while stopped.

The technical problems to be achieved in the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned will be clearly understood by a person having ordinary skill in the technical field to which the present invention belongs from the description below.

In order to solve the technical problem as described above, a control method of a hybrid vehicle according to an embodiment of the present invention may include the steps of: calculating an engine start-up remaining time according to an electric load when the vehicle is stopped; performing a first comparison between a target rest time and the engine start-up remaining time; if the target rest time is longer as a result of the first comparison, charging a battery using the power of the engine; performing a second comparison between the updated engine start-up remaining time and the remaining target rest time; and if the second comparison result is that the remaining target rest time is shorter than the updated engine start-up remaining time, stopping the engine start.

In addition, a hybrid vehicle according to one embodiment of the present invention may include a hybrid controller having an engine operation remaining time calculation unit that calculates an engine operation remaining time according to an electrical load when the vehicle is stopped, and a stop time securing control unit that performs a first comparison between a target rest time and the engine operation remaining time, and if the target rest time is longer as a result of the first comparison, determines charging of a battery using the power of the engine, and performs a second comparison of the updated engine operation remaining time by the engine operation remaining time calculation unit according to the charging of the battery with the remaining target rest time, and if the remaining target rest period is shorter than the updated engine operation remaining time as a result of the second comparison, determines stopping the engine operation.

A hybrid vehicle according to at least one embodiment of the present invention configured as described above can provide passengers with a more comfortable resting environment while stopped.

In particular, according to embodiments of the present invention, since the battery charge state required for the target rest time is secured in advance or at the beginning of a stop, engine start-up during rest can be prevented.

The effects obtainable from the present invention are not limited to the effects mentioned above, and other effects not mentioned will be clearly understood by those skilled in the art to which the present invention belongs from the description below.

Figure 1 shows an example of the powertrain structure of a typical parallel hybrid vehicle.
Figure 2 shows an example of how engine starting is performed while the vehicle is stopped in a typical hybrid vehicle.
FIG. 3 is a block diagram showing an example of a control system of a hybrid vehicle to which embodiments of the present invention can be applied.
FIG. 4 is a block diagram showing an example of a controller structure for performing engine start control while stopped according to one embodiment of the present invention.
FIG. 5 is a flowchart showing an example of a process for controlling engine start while stopped according to one embodiment of the present invention.
Figure 6 shows an example of a form of engine start control while stopped according to one embodiment of the present invention.
Figure 7 shows another example of a form of engine start control while stationary in one embodiment of the present invention.

Hereinafter, with reference to the attached drawings, embodiments of the present invention will be described in detail so that those skilled in the art can easily practice the present invention. However, the present invention may be implemented in various different forms and is not limited to the embodiments described herein. In addition, in order to clearly describe the present invention in the drawings, parts that are not related to the description are omitted, and similar parts are assigned similar drawing reference numerals throughout the specification.

Throughout the specification, whenever a part is said to "include" a certain component, this does not mean that it excludes other components, but rather that it may include other components, unless otherwise specifically stated. Furthermore, parts designated by the same reference numerals throughout the specification refer to the same components.

Before describing a hybrid vehicle performing engine start control during a stop according to an embodiment of the present invention and a control method thereof, a control system of a hybrid vehicle applicable to the embodiments will first be described. A basic powertrain structure of a hybrid vehicle applicable to the embodiments of the present invention may be the structure illustrated in FIG. 1. The interrelationships between controllers in a vehicle to which such a powertrain is applied are illustrated in FIG. 3.

FIG. 3 is a block diagram showing an example of a control system of a hybrid vehicle to which embodiments of the present invention can be applied.

Referring to FIG. 3, in a hybrid vehicle to which embodiments of the present invention can be applied, an internal combustion engine (110) is controlled by an engine controller (210), a starter/generator motor (120) and an electric motor (140) can have their torque controlled by a motor controller (MCU: Motor Control Unit, 220), and an engine clutch (130) can be controlled by a clutch controller (230). Here, the engine controller (210) is also called an engine control system (EMS: Engine Management System). In addition, the transmission (150) is controlled by a transmission controller (250). In some cases, a controller for the starter/generator motor (120) and a controller for each of the electric motors (140) may be provided separately.

Each controller is connected to a hybrid controller (HCU: Hybrid Controller Unit, 240) that controls the entire mode switching process as its upper controller, and can provide information necessary for changing driving modes, controlling engine clutch during gear shifting, and/or controlling engine stop to the hybrid controller (240) or perform operations according to control signals.

More specifically, the hybrid controller (240) determines whether to perform mode switching according to the driving state of the vehicle. For example, the hybrid controller determines the release (Open) timing of the engine clutch (130), and performs hydraulic pressure (in the case of wet EC) control or torque capacity control (in the case of dry EC) at the time of release. In addition, the hybrid controller (240) can determine the state (Lock-up, Slip, Open, etc.) of the engine clutch (130) and control the fuel injection stop timing of the engine (110). In addition, the hybrid controller can control engine rotation energy recovery by transmitting a torque command for controlling the torque of the starter-generator motor (120) for engine stop control to the motor controller (220). In addition, the hybrid controller (240) can control the lower controller for judging and switching the mode switching condition during the driving mode switching control.

Of course, it is obvious to those skilled in the art that the above-described control period connection relationship and the functions/divisions of each controller are exemplary and are not limited to the names. For example, the hybrid controller (240) may be implemented so that the corresponding function is provided by replacing it in any one of the other controllers, or the corresponding function may be provided by distributing it in two or more of the other controllers.

The configuration of Fig. 3 described above is only an example of a hybrid vehicle configuration, and it will be apparent to those skilled in the art that hybrid vehicles applicable to the embodiment are not limited to this structure.

In one embodiment of the present invention, in order to prevent intermittent or periodic engine starting due to SOC drop during a stop, it is proposed to secure SOC in advance by considering the electric load consumed during rest at the beginning of a stop or before a stop.

FIG. 4 is a block diagram showing an example of a controller structure for performing engine start control while stopped according to one embodiment of the present invention.

Referring to FIG. 4, a controller (300) for performing engine start control according to an embodiment may have at least one of a gear, a battery SOC, an engine start reference SOC, electrical load information, and a target rest time as input values. Here, the gear information may be obtained from a transmission controller (250), the battery SOC may be obtained from a battery management system (BMS), and the engine start reference SOC may be obtained from a hybrid controller (240) or may be a pre-stored value. The engine start reference SOC is a value corresponding to the engine On reference of FIG. 1, and may be an SOC set to be secured to a minimum in order to prevent a decrease in the system efficiency of the powertrain, and when the SOC decreases to the corresponding value, the hybrid controller (240) typically forcibly starts the engine to perform charging.

In addition, the electric load information may be acquired from the body controller, or may be acquired from a low DC-DC converter (LDC) that transforms the power of the main battery and supplies power to the electric load. In addition, the target rest time may be information input by the driver through a predetermined input means (e.g., a button, a switch, a touch screen, etc.) at the start of the rest/stop or before that (e.g., before departure), a preset fixed value may be used, or may be a value acquired through cumulative learning by location/time based on the driver's rest pattern.

Of course, the method of obtaining each input information described above is exemplary and is not necessarily limited thereto, and it is obvious to those skilled in the art that various changes are possible.

Meanwhile, the controller (300) for performing engine start control may include an engine start remaining time calculation unit (310) that calculates the engine start remaining time corresponding to the time remaining from the present time until the time when the engine is forcibly started due to power consumption factors such as a field load. In addition, the controller (300) may include a stop time securing control unit (320) that controls to secure the SOC required for the target rest time at an early stage if it is insufficient based on the engine start remaining time calculated by the engine start remaining time calculation unit (310).

The controller (300) for performing engine start control may be configured as a separate controller for performing the control, or may be implemented in the form of a function or module of the hybrid controller (240), but is not necessarily limited thereto.

Below, the functions of each part (310, 320) included in the controller (300) for performing engine start control will be described in detail with reference to FIG. 5.

FIG. 5 is a flowchart showing an example of a process for controlling engine start while stopped according to one embodiment of the present invention.

Referring to Fig. 5, first, the engine start remaining time calculation unit (310) can determine whether the control entry condition of the engine start remaining time calculation is satisfied (S411). For example, the engine start remaining time calculation unit (310) can determine whether the control entry condition is satisfied based on whether the current gear is in the parking (P) gear and the engine is maintained in an on (IG ON) state (for a certain period of time).

When the control entry condition is satisfied, the engine start remaining time calculation unit (310) can calculate the engine start remaining time based on the current electric load information and the engine start reference SOC (S413). In this process, assuming that the load amount according to the current electric load information is maintained, the engine start remaining time can be calculated as shown in the following mathematical expression 1.

In mathematical expression 1 is the remaining engine start time, The available SOC is the battery energy reserve after subtracting the engine start-up reference SOC from the current SOC. Each represents the total load.

The calculated engine start remaining time can be output to the outside (S415). Specifically, the engine start remaining time is transmitted to the stopping time securing control unit (320), and according to an embodiment, may be output through a display means within the vehicle (e.g., a cluster, a display of a head unit, a head-up display, etc.).

The fluctuation of battery SOC It affects the overall load ( ) also affects the remaining engine start time, and the engine start remaining time calculation unit (310) monitors whether there is a change in SOC and electric load (S417), and when at least one of them changes, the engine start remaining time can be updated (in real time) (S413). At this time, the monitoring can be performed periodically or can be performed continuously in real time during control.

Meanwhile, when the stop time securing control unit (320) receives a target rest time (S421), it determines whether the target rest time is longer than the engine start remaining time obtained from the engine start remaining time calculation unit (310) (S423).

If the target rest time is longer, which means that the engine starts before the rest time ends, the stop time securing control unit (320) can decide to enter series mode charging (S425). At this time, the operating point of the engine (110) during series mode charging can be set to a separate operating point in the low rpm range that gives priority to noise.

As the series mode charging is initiated, the SOC of the battery increases, and accordingly, the engine start remaining time calculation unit (310) updates (S413) the engine start remaining time through monitoring (S417), and the updated information can be acquired again by the stopping time securing control unit (320). Accordingly, the stopping time securing control unit (320) determines whether the remaining target rest time, which is the remaining target rest time at the current point in time, is less than or equal to the engine start remaining time at the current point in time (S427). If the remaining target rest time is less than or equal to the engine start remaining time at the current point in time, a transition to the EV mode can be determined since the engine start does not occur during the remaining target rest time. On the other hand, if the remaining target rest time is greater, the series mode charging can be continuously performed.

Of course, if the target rest time at step S423 is less than or equal to the remaining engine start time (no in S423), entry into EV mode is determined immediately and engine start is not performed from the beginning of rest/stop.

Through the control process described above, if the driver wishes to rest after stopping (i.e., inputs a target rest time), the engine can be started immediately at the beginning of the rest period to secure the necessary SOC if the current SOC is insufficient compared to the total load, thereby resolving the inconvenience caused by the engine being started at an unexpected time during the rest period. An example of this control form is described with reference to Fig. 6.

Figure 6 shows an example of a form of engine start control while stopped according to one embodiment of the present invention.

Referring to Fig. 6, the target rest time is input in the stopped state (i.e., the P-stage input and the IG ON state are maintained for a certain period of time or longer). Accordingly, the engine start remaining time is calculated, but the target rest time is longer than that. Therefore, in a general hybrid vehicle, the engine will be started if the engine start remaining time expires before the target rest time elapses. However, according to the embodiment, since it is determined that the engine start remaining time is shorter than the target rest time, the SOC is secured through series mode charging in the initial stage of the stop/rest until the remaining target rest time becomes less than or equal to the engine start remaining time. Therefore, except for the engine start for the initial charge, no additional engine start occurs during the target rest time.

Meanwhile, the SOC required for the target rest period can also be secured before stopping. This is explained with reference to Fig. 7.

Figure 7 shows another example of a form of engine start control while stationary in one embodiment of the present invention.

Referring to FIG. 7, the destination and target rest time before departure can be input in advance. In this case, the hybrid controller (240) can schedule the driving strategy by judging the path to the destination and its driving conditions (e.g., slope, distance, traffic congestion, etc.). In this case, the controller (300) according to the embodiment can predict the total load during rest by excluding the load required for driving from the current total load, and calculate the rest required SOC, which is the SOC required for the target rest time, based on this. Accordingly, the controller (300) according to the embodiment adds the engine start reference SOC to the rest required SOC and notifies the hybrid controller (240) of the target SOC, so that the hybrid controller (240) can perform mode control during driving so as to satisfy the target SOC upon arrival at the destination. Accordingly, even if the driver arrives at the destination, stops (P gear input and IG ON maintained) and takes a rest, the engine is not started during the rest because the rest required SOC is secured during driving.

Similarly, in the case of a plug-in hybrid vehicle (PHEV), when a destination and target rest time are input during a reservation charging, the charging schedule can be performed so that an SOC corresponding to the SOC required to travel to the destination plus the SOC required for rest is secured before departure.

Of course, in the case of Fig. 7 or PHEV, if the target SOC is not satisfied upon arrival at the destination, the engine start-up during rest can be prevented by additionally securing the necessary SOC through initial engine start-up when stopped as described above with reference to Figs. 4 to 6.

The above-described present invention can be implemented as a computer-readable code on a medium in which a program is recorded. The computer-readable medium includes all kinds of recording devices that store data that can be read by a computer system. Examples of the computer-readable medium include a hard disk drive (HDD), a solid state disk (SSD), a silicon disk drive (SDD), a ROM, a RAM, a CD-ROM, a magnetic tape, a floppy disk, an optical data storage device, etc.

Accordingly, the above detailed description should not be construed as restrictive in all respects but should be considered as illustrative. The scope of the invention should be determined by a reasonable interpretation of the appended claims, and all changes within the equivalent scope of the invention are intended to be included in the scope of the invention.

Claims (19)

Step for calculating the remaining engine start time according to the total load when the vehicle is stopped;
A first step of comparing the target rest time with the remaining engine start time;
In the first comparison result, if the target rest time is longer, a step of performing battery charging using engine power;
A second step of comparing the updated remaining engine start time with the remaining target rest time according to the charging of the above battery; and
In the second comparison result, if the remaining target rest time is less than or equal to the updated engine start remaining time, a step of stopping the start of the engine is included.
All of the above steps are performed in a stationary state,
The above target rest time is obtained through cumulative learning by location or time based on the driver's rest pattern.
Control method of hybrid vehicle. In the first paragraph,
The step of calculating the remaining engine start time is as follows:
A method for controlling a hybrid vehicle, comprising the step of dividing the available state of charge of the battery by the electric load. In the second paragraph,
The above available charging status is,
A control method for a hybrid vehicle, which is obtained by subtracting a preset engine start reference charge state from the current battery charge state. delete In the first paragraph,
A method for controlling a hybrid vehicle, further comprising the step of outputting the remaining engine operation time through a display means. In the first paragraph,
The step of calculating the remaining engine start time is as follows:
A control method for a hybrid vehicle, performed when the transmission is in the Park (P) position and the IG On state is maintained for a certain period of time. In the first paragraph,
The steps for performing the above charging are:
A method for controlling a hybrid vehicle, comprising the step of generating electricity using the power of the engine from a starter generator motor connected to the engine. In the first paragraph,
The remaining engine start time is:
A control method for a hybrid vehicle, wherein the control is recalculated when the state of charge of the battery or the electrical load is changed. In the first paragraph,
The step of stopping the above engine is:
A method of controlling a hybrid vehicle, comprising a step of entering an electric vehicle (EV) mode. A computer-readable recording medium recording a program for executing a method for controlling a hybrid vehicle according to any one of claims 1 to 3 and claims 5 to 9. An engine start-up remaining time calculation unit that calculates the engine start-up remaining time according to the total load when the vehicle is stopped, and
A hybrid controller including a stop time securing control unit that performs a first comparison between a target rest time and the engine start remaining time, and if the target rest time is longer as a result of the first comparison, determines charging of a battery using the power of the engine, and performs a second comparison of the updated engine start remaining time in the engine start remaining time calculation unit according to the charging of the battery with the remaining target rest time, and if the remaining target rest time is shorter than the updated engine start remaining time as a result of the second comparison, determines stopping the engine start,
The calculation of the remaining engine start time, the first comparison, the charging of the battery, the second comparison, and the decision to stop the engine start are performed in a stationary state.
The above target rest time is obtained through cumulative learning by location or time based on the driver's rest pattern.
Hybrid car. In Article 11,
The above engine start remaining time calculation unit,
A hybrid vehicle, wherein the remaining engine operation time is calculated by dividing the available charge state of the battery by the electric load. In Article 12,
The above available charging status is,
A hybrid vehicle in which the current battery charge state is subtracted from the preset engine start-up reference charge state. delete In Article 11,
A hybrid vehicle further comprising a display means for displaying the remaining engine operation time. In Article 11,
The above engine start remaining time calculation unit,
A hybrid vehicle, wherein the remaining engine operation time is calculated when the transmission is in the Park (P) position and the IG On state is maintained for a certain period of time. In Article 11,
Further comprising a starter generator motor connected to the above engine,
Charging of the above battery is
A hybrid vehicle that operates by utilizing power generated by the engine from the above-mentioned starting generator motor. In Article 11,
The above engine start remaining time calculation unit is,
A hybrid vehicle, wherein the state of charge of the battery and the electrical load are monitored for changes, and the remaining engine start time is recalculated if at least one of the state of charge of the battery and the electrical load is changed. In Article 11,
The above hybrid controller,
A hybrid vehicle that is controlled to enter electric vehicle (EV) mode when it is determined that the engine is to be stopped.