Hybrid vehicles and their control methods

Abstract

This disclosure relates to a hybrid vehicle and a control method thereof, the method comprising: receiving traffic light information including signal information and distance information of a traffic light ahead when an EV mode is entered; predicting the duration of the EV mode based on the received traffic light information; predicting the coolant temperature in the EV mode according to the predicted duration of the EV mode; comparing the predicted coolant temperature with a reference temperature at which the fully automatic temperature control (FATC) unit requests engine start; and entering the EV mode when the predicted coolant temperature is higher than the reference temperature.

Description

[0001] Cross-reference to related applications

[0002] This application claims priority to Korean Patent Application No. 10-2020-0077843, filed on June 25, 2020, which is incorporated herein by reference as if it were fully contained herein. Technical Field

[0003] This disclosure relates to a hybrid vehicle and a control method thereof, and more specifically to a hybrid vehicle and a control method thereof capable of predicting the duration of an electric vehicle (EV) mode based on traffic light information and estimating the corresponding coolant temperature, thereby minimizing the entry of a series hybrid electric vehicle (HEV) mode for indoor heating. Background Technology

[0004] Generally, a hybrid electric vehicle (HEV) refers to a vehicle that uses two types of power sources: an engine and an electric motor. This type of hybrid vehicle relies on the coordinated operation of both power sources—the engine and the motor—to produce optimal output and torque. Specifically, in hybrid vehicles employing parallel or transmission-mounted electric device (TMED) hybrid systems that integrate an electric motor and an engine clutch (EC) between the engine and transmission, the output of the engine and the motor can be simultaneously transmitted to the drive shaft.

[0005] Under normal circumstances, hybrid vehicles operate in Electric Vehicle (EV) mode at the start of acceleration, where they use only the electric motor. Subsequently, when greater driving force is needed, the driving mode switches to Hybrid Electric Vehicle (HEV) mode, in which power is generated by operating both the electric motor and the engine simultaneously. HEV mode, where the electric motor and engine operate together, can be categorized into parallel HEV mode and series HEV mode, depending on the primary power source.

[0006] In parallel HEV mode, the engine's power is used for driving. However, in series HEV mode, the engine operates under low load, so its power is used to generate electricity. Parallel HEV mode is more efficient than series HEV mode. However, since TMED hybrid vehicles typically do not have a torque converter, unlike conventional internal combustion engine vehicles, it is difficult to maintain engine operation below a predetermined speed. Therefore, when driving at low speeds below the predetermined speed, TMED hybrid vehicles are driven in series HEV mode.

[0007] In a recently developed vehicle, a full automatic temperature control (FATC) unit is responsible for air conditioning operation. In the case of a hybrid vehicle, the FATC unit performs control to perform indoor heating using engine cooling water heated by heat of an engine as needed. In particular, when the temperature of the engine cooling water is less than a temperature required for the FATC unit to perform indoor heating, the FATC unit requests a hybrid control unit (HCU) to start the engine. Accordingly, the HCU starts the engine and selects one of a parallel mode and a series mode as the case can be.

[0008] Figure 1 A graph for explaining a problem of HEV mode switching control when a vehicle stops due to a traffic signal light in a travel condition in which indoor heating is required is shown. Figure 1 A vehicle speed graph, a graph indicating a change in a value of an accelerator pedal position sensor (APS), a travel mode graph, and a cooling water temperature graph are shown. The horizontal axis of each of these graphs indicates time.

[0009] The first interval SI is an interval in which the vehicle travels at a speed at which the vehicle can travel in the parallel mode. In the parallel mode, power of the engine is used as a driving force, so the temperature of the engine cooling water can increase due to heat of the engine. As the parallel mode travel time increases, the temperature of the cooling water increases, and engine cooling water whose temperature is higher than a reference temperature is able to be used as an energy source for indoor heating.

[0010] The second interval S2 is an interval in which the vehicle decelerates to stop due to a stop signal of a traffic signal light, such as a red light. As operation of the accelerator pedal is stopped to decelerate and the vehicle speed decreases, the travel mode is switched to the EV mode. Thus, the engine is stopped from operating, so the temperature of the cooling water decreases.

[0011] The third interval S3 is an interval in which the engine is driven to perform indoor heating in a state in which the vehicle is stopped or travels at a low speed. When the vehicle is stopped or travels at a low speed, the engine is stopped, so the temperature of the cooling water decreases. When the temperature of the cooling water is equal to or lower than a predetermined level, it can not be possible to secure a heating performance required by a driver. Thus, when the temperature of the cooling water decreases to a first reference value (FATC ON temperature), the FATC unit requests the HCU to drive the engine. The HCU drives the engine to increase the temperature of the cooling water according to the request of the FATC unit. When the engine is started, one of the parallel mode and the series mode can be selected. However, when the vehicle is in the third interval S3, that is, in a state in which it travels at a low speed or is stopped, the vehicle enters the series HEV mode.

[0012] The fourth section S4 is a section in which the series HEV mode for indoor heating is terminated and the vehicle waits until the signal of the traffic signal light switches to a signal for traveling, for example, a green light. When the temperature of the cooling water increases and reaches the second reference value (FATC-off temperature) at which indoor heating can be performed due to the series HEV mode, the FATC unit requests the HCU to stop the engine. The HCU stops the engine in accordance with the request of the FATC unit to terminate the series HEV mode. Since the engine is stopped, the temperature of the cooling water decreases.

[0013] The fifth section S5 is a section in which the vehicle resumes traveling in response to the signal for traveling of the traffic signal light and travels at a speed at which the vehicle can travel in the parallel mode.

[0014] As described above, when the temperature of the cooling water decreases in the traveling condition in which indoor heating is required, the engine needs to be driven to perform indoor heating. When the engine is started to perform indoor heating, it is advantageous to drive the vehicle in the parallel HEV mode in terms of improvement in fuel efficiency and increase in the temperature of the cooling water. However, in a state in which the vehicle travels at low speed or stops due to, for example, a traffic signal light, it is difficult to satisfy the vehicle speed at which the vehicle can enter the parallel HEV mode, and thus the vehicle needs to travel in the series HEV mode.

[0015] In particular, in an extremely cold environment, the request of the FATC unit to drive the engine can be maintained for a long time, or can be frequently made. Therefore, the vehicle is driven in the series HEV mode rather than the EV mode to adjust the temperature of the cooling water, resulting in a decrease in fuel efficiency. SUMMARY

[0016] Accordingly, the present disclosure relates to a hybrid vehicle and a control method thereof that substantially obviate one or more problems due to limitations and disadvantages of the related art. An object of the present disclosure is to provide a hybrid vehicle and a control method thereof that can minimize traveling in a series HEV mode for indoor heating in a traveling condition in which indoor heating is required, thereby minimizing a decrease in fuel efficiency. However, the objects that the exemplary embodiments want to achieve are not limited to the above-mentioned objects, and other objects not mentioned herein will be clearly understood by persons skilled in the art from the following description.

[0017] To achieve the above and other objects, a control method of a hybrid vehicle according to an exemplary embodiment of the present disclosure can include: receiving traffic signal information including signal information and distance information of a front traffic signal light in an EV mode entry condition; predicting a duration of the EV mode based on the received traffic signal information; predicting a cooling water temperature in the EV mode according to the predicted duration of the EV mode; comparing the predicted cooling water temperature with a reference temperature at which a full automatic temperature control (FATC) unit requests start of an engine; and entering the EV mode when the predicted cooling water temperature is higher than the reference temperature.

[0018] In addition, a hybrid vehicle according to an exemplary embodiment of the present disclosure can include a first controller configured to receive traffic signal information including signal information and distance information of a front traffic signal light, and a second controller configured to predict a duration of an EV mode based on the received traffic signal information, predict a cooling water temperature in the EV mode according to the predicted duration of the EV mode, compare the predicted cooling water temperature with a reference temperature at which a full automatic temperature control (FATC) unit requests start of an engine, and enter the EV mode when the predicted cooling water temperature is higher than the reference temperature. BRIEF DESCRIPTION OF DRAWINGS

[0019] The accompanying drawings are included to provide a further understanding of the present disclosure and are incorporated in and constitute a part of this application, illustrate exemplary embodiments of the present disclosure, and together with the description serve to explain the principles of the present disclosure. In the drawings:

[0020] Figure 1 A graph for explaining a problem of HEV mode switching for indoor heating in a conventional hybrid vehicle according to the related art is illustrated;

[0021] Figure 2 An example of a structure of a powertrain of a hybrid vehicle to which an exemplary embodiment of the present disclosure is applicable is illustrated;

[0022] Figure 3 A block diagram illustrating an example of a control system of a hybrid vehicle to which an exemplary embodiment of the present disclosure is applicable is illustrated;

[0023] Figure 4 A flowchart schematically illustrating a control procedure of a hybrid vehicle according to an exemplary embodiment of the present disclosure is illustrated;

[0024] Figure 5 A graph for explaining a method of predicting a duration of an EV mode based on traffic signal information in a hybrid vehicle according to an exemplary embodiment of the present disclosure is illustrated;

[0025] Figure 6is a diagram for explaining a method of predicting a temperature of cooling water in a hybrid vehicle according to an example embodiment of the present disclosure;

[0026] Figure 7 is a flowchart showing a control procedure of a hybrid vehicle according to a first example embodiment of the present disclosure;

[0027] Figure 8 is a flowchart showing a control procedure of a hybrid vehicle according to a second example embodiment of the present disclosure; and

[0028] Figure 9 is a graph showing an effect of HEV mode switching for indoor heating in a hybrid vehicle of the present disclosure. DETAILED DESCRIPTION

[0029] It is understood that the term "vehicle" or "vehicular" or other similar terms as used herein, includes a motor vehicle generally, including a sport utility vehicle (SUV), a bus, a truck, passenger car, including a variety of car models, including electric cars, a watercraft including a variety of models of boats and ships, an aircraft, and the like, and includes hybrid vehicles, electric vehicles, plug-in hybrid electric vehicles, hydrogen powered vehicles and other alternative fuel (e.g., resources other than petroleum) vehicles as well as a variety of non-automotive vehicles. As referred to herein, a hybrid vehicle is a vehicle having two or more power sources, such as a gasoline powered and electric powered vehicle.

[0030] While example embodiments are described as using a plurality of units to perform example procedures, it is understood that example procedures can also be performed by one or more modules. In addition, it is understood that the term controller / control unit refers to a hardware device that includes a memory and a processor and is specifically programmed to perform the procedures described herein. The memory is configured to store modules and the processor is specifically configured to execute the modules to perform one or more procedures described further below.

[0031] Further, the control logic of the present disclosure can be implemented as a non-transitory computer readable medium having stored thereon executable program instructions that are executed by a processor, controller / control unit, and / or the like, to cause the processor, controller / control unit, and / or the like, to carry out operations described herein. Examples of computer readable mediums include, but are not limited to, ROM, RAM, compact discs (CD)-ROMs, magnetic tape, floppy disks, flash drives, smart cards, and optical data storage devices. The computer readable recording medium can also be distributed over network coupled computer systems so that the computer readable medium is stored in a distributed fashion throughout the network-coupled computer systems. For example, the computer readable medium can be a distributed network and the program instructions to perform one or more of the procedures described herein are stored in a distributed fashion at different locations on the network.

[0032] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present disclosure. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and / or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. As used herein the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0033] As used herein, the term "about" shall generally be construed to be within the normal tolerances of the art, for example within 2 standard deviations of the mean. "About" can be construed to be within 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, 0.5%, 0.1%, 0.05%, or 0.01% of the stated value. Unless otherwise specifically stated in the context, all numerical values provided herein are modified by the term "about."

[0034] Hereinafter, exemplary embodiments of the present disclosure will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily practice the exemplary embodiments. However, the present disclosure can be implemented in many different ways and should not be construed as being limited to the exemplary embodiments set forth herein. In the drawings, parts irrelevant to the description of the present disclosure will be omitted for the sake of clarity. Throughout the specification, like reference numerals refer to like elements.

[0035] Throughout the specification, when a certain part "comprises" or "includes" a certain component, this indicates that other components are not excluded and, unless otherwise stated, can further include other components. The same reference numerals used throughout the specification refer to the same constituent elements.

[0036] Figure 2 An example of a structure of a powertrain of a hybrid vehicle to which an exemplary embodiment of the present disclosure is applicable is illustrated. Figure 2 An example of a powertrain of a hybrid vehicle employing a parallel type hybrid system is illustrated, in which an electric motor (or drive motor) 140 and an engine clutch (EC) 130 are installed between an internal combustion engine (ICE) 110 and a transmission 150.

[0037] In such a vehicle, when the driver steps on the accelerator pedal after starting the vehicle, the power of the battery can be first used to drive the motor 140 in a state where the engine clutch 130 is open, and then the power of the motor can be transmitted to the wheels via the transmission 150 and the final drive (FD) 160 to rotate the wheels (i.e., EV mode). When more driving force is required as the vehicle accelerates, the assist motor (or starter / generator motor) 120 can operate to drive the engine 110.

[0038] When the rotational speeds of the engine 110 and the motor 140 become equal, the engine clutch 130 is locked, so that the engine 110 and the motor 140 together or only the engine 110 drive the vehicle (i.e., transition from EV mode to HEV mode). When a predetermined engine-off condition is satisfied, for example, when the vehicle decelerates, the engine clutch 130 is released, and the engine 110 is stopped (i.e., transition from HEV mode to EV mode). In addition, when the hybrid vehicle is braked, the driving force of the wheels is converted into electric energy, and the electric energy is used to charge the battery, which is called regenerative braking or regeneration of braking energy.

[0039] When the engine is started, the starter / generator motor 120 operates as a starter motor, and when the rotational energy of the engine is recovered after the engine is started or when the engine is turned off, the starter / generator motor 120 operates as a generator. Therefore, the starter / generator motor 120 can be referred to as a "hybrid starter generator (HSG)", or in some cases, can also be referred to as an "assist motor".

[0040] The relationship between the controllers in a vehicle to which the above-described powertrain is applied is shown in Figure 3 . Figure 3 is a block diagram showing an example of a control system of a hybrid vehicle to which an exemplary embodiment of the present disclosure can be applied.

[0041] Referring to Figure 3 , in a hybrid vehicle to which an exemplary embodiment of the present disclosure can be applied, the internal combustion engine 110 can be operated by an engine controller 210, and the torques of the starter / generator motor 120 and the motor 140 can be operated by a motor control unit (MCU) 220. The engine clutch 130 can be operated by a clutch controller 230. In particular, the engine controller 210 can be referred to as an engine management system (EMS). In addition, the transmission 150 can be operated by a transmission controller 250. In some cases, a controller configured to operate the starter / generator motor 120 and a controller configured to operate the motor 140 can be provided separately from each other.

[0042] Each of the controllers can be connected to a hybrid control unit (HCU) 240, which is a higher-level controller configured to perform the entire process of mode switching, and each of the controllers can provide the hybrid control unit 240 with information required for engine clutch control at the time of switching the driving mode or the gear shift, and / or information required for engine stop control, or can perform an operation in response to a control signal under the operation of the hybrid control unit 240. More specifically, the hybrid control unit 240 can be configured to determine whether to perform a mode switching operation depending on the driving state of the vehicle.

[0043] For example, the hybrid control unit can be configured to determine the time to open the engine clutch 130. When the engine clutch 130 is opened, the hybrid control unit can be configured to perform hydraulic control (in the case of a wet-type engine clutch) or torque capacity control (in the case of a dry-type engine clutch). In addition, the hybrid control unit 240 can be configured to determine the state of the engine clutch (e.g., lock-up, slip, open, etc.) and adjust the time to stop injecting fuel into the engine 110. In addition, the hybrid control unit can be configured to transmit a torque command for adjusting the torque of the start / generation motor 120 to the motor controller 220 to control engine stop, thereby controlling the recovery of engine rotational energy. In addition, according to an exemplary embodiment of the present disclosure, the hybrid control unit 240 can be configured to determine a mode switching condition at the time of mode switching control and operate the lower-level controllers to perform mode switching, which will be described later.

[0044] Of course, it will be apparent to those skilled in the art that the connection relationship between the above controllers / control units and the functions / divisions of the controllers / control units are illustrative and are not limited by their names. For example, the hybrid control unit 240 can be implemented such that its functions are provided by any one controller other than the hybrid control unit 240, or such that its functions are distributed and provided by two or more other controllers.

[0045] In addition, although the above describes the transmission-mounted electric drive (TMED) type parallel hybrid vehicle with reference to Figure 2 and Figure 3 However, this is merely exemplary, and exemplary embodiments of the present disclosure are not limited to any particular type of hybrid vehicle. Exemplary embodiments of the present disclosure are applicable to any type of hybrid vehicle as long as indoor heating can be achieved using heat generated by the operation of the engine.

[0046] Hereinafter, a more efficient control method according to exemplary embodiments of the present disclosure will be described based on the above-described structure of the vehicle. Figure 4 is a flowchart schematically illustrating a control procedure of a hybrid vehicle according to exemplary embodiments of the present disclosure. Referring to Figure 4 In exemplary embodiments of the present disclosure, a duration of an EV mode can be predicted based on traffic signal information (S10), and a temperature of reduced cooling water can be estimated (S20). When a series HEV mode is expected to occur based on the estimated temperature of the cooling water, the occurrence of the series HEV mode can be prevented or minimized (S30).

[0047] When the duration of the EV mode is predicted based on the traffic signal information in step S10, the traffic signal information can include at least one of a signal change period of a front traffic signal, a currently displayed signal ahead of a current route, a remaining distance to the front traffic signal, a remaining time of the currently displayed signal, next signal display information, or traffic signal location information. In addition to the traffic signal information, traffic information such as information about a road to the front traffic signal, congestion in each section, and an average speed in each section can be further included. It can be assumed that the traffic signal information and the traffic information are received through an audio / video / navigation (AVN) system, but this is merely illustrative.

[0048] Exemplary embodiments of the present disclosure are not limited to any particular controller or system as long as wireless communication can be performed with an entity that provides traffic information. For example, traffic signal information can be acquired from a telematics center via a telematics modem or through data center / server / cloud access using a wireless communication module, and vehicle speed information can be acquired using various sensors installed inside the vehicle. The duration of the EV mode can be predicted based on the traffic signal information.

[0049] Figure 5 is a graph for explaining a method of predicting a duration of an EV mode based on traffic signal information according to exemplary embodiments of the present disclosure. Referring to Figure 5 The duration of the EV mode can be calculated using a time t1 taken for the vehicle to reach the traffic signal and a signal waiting time t2 remaining until a go signal of the traffic signal, e.g., a green light, is turned on.

[0050] The time t1 taken to reach the traffic signal can be calculated by substituting a remaining distance d1 to the traffic signal and a vehicle speed into Equation 1 below.

[0051] Equation 1

[0052] t1 = d1 / vehicle speed

[0053] where t1 denotes a time required to reach a traffic signal, and d1 denotes a remaining distance to the traffic signal.

[0054] The signal waiting time t2 can be calculated by substituting the remaining time of the current signal and the remaining time of the next signal into the following logical formula 1.

[0055] Logical formula 1

[0056] If t1 > t_now,

[0057] Predicted signal = next signal,

[0058] t2 = t_next - t_now

[0059] Else

[0060] Predicted signal = current signal

[0061] t2 = t_now - t1

[0062] where t_now denotes the remaining time of the current signal, and t_next denotes the remaining time of the next signal.

[0063] If the predicted signal according to the above logical formula 1 is "stop", the duration of the EV mode t_EV can be calculated as follows: t_EV = t1 + t2, and if the predicted signal is "go", the duration of the EV mode t_EV can be calculated as follows: t_EV = 0. When the duration of the EV mode is predicted, the process of estimating the temperature of the cooling water, step S20, can be performed.

[0064] Figure 6 is a diagram for explaining a method of predicting the temperature of cooling water in a hybrid vehicle according to an exemplary embodiment of the present disclosure. Referring to Figure 6 The temperature change of the engine cooling water can be calculated using the heat Q engine received from the engine, Out the heat Q Fatc for indoor heating. This is expressed by the following Equation 2.

[0065] Equation 2

[0066]

[0067] where Q engine denotes the heat received from the engine, Q Out denotes the heat discharged to the atmosphere (Q Out = f (outside air temperature, engine cooling water temperature)), and Q Fatc denotes the heat for indoor heating (Q Fatc= f (set temperature, indoor temperature), C represents the heat capacity of the engine coolant, and M represents the mass of the engine coolant.

[0068] The predicted coolant temperature T Final can be calculated using Equation 3 below using the ΔT calculated by Equation 2 above. initial

[0069] Equation 3

[0070]

[0071] When the predicted coolant temperature T Final is obtained by the above calculation process, it can be determined whether the FATC unit will request driving of the engine at the time of entry into the EV mode. In other words, when the predicted coolant temperature T Final is equal to or lower than a first reference value (FATC ON temperature) required for the FATC unit to perform indoor heating, it can be predicted that the FATC unit will request driving of the engine at the time of entry into the EV mode, and thus control can be performed to minimize operation in the series HEV mode.

[0072] As a control method to minimize operation in the series HEV mode when the FATC unit requests driving of the engine, the engine stop time can be delayed as much as possible before entry into the EV mode, or the heating performance of the FATC unit can be reduced. Alternatively, these two methods can be used together.

[0073] Figure 7 is a flowchart showing a control process of a hybrid vehicle according to the first example embodiment of the present disclosure. Specifically, Figure 7 an embodiment in which the engine stop time is delayed as much as possible to minimize operation in the series HEV mode is shown.

[0074] Referring to Figure 7 , when switching to the EV mode is requested (S110), the duration of the EV mode can be predicted based on traffic signal information (S120). The duration of the EV mode can be predicted by calculating the time t1 taken for the vehicle to decelerate and reach the traffic signal and the signal waiting time t2 remaining until the travel signal of the traffic signal, for example, the green light, is turned on.

[0075] When the duration of the EV mode is predicted, the temperature change of the coolant can be predicted (S130). The predicted coolant temperature T Final can be calculated by reflecting the change in heat during the EV mode in the initial coolant temperature T initial . Thereafter, it can be determined whether the calculated predicted coolant temperature T Final ​whether it is a low cooling water temperature equal to or lower than a first reference value (FATC ON temperature) required for the FATC unit to perform indoor heating (S140).

[0076] in response to determining that the predicted cooling water temperature T Final is not a low cooling water temperature, the temperature of the engine cooling water is sufficient to maintain indoor heating even if the EV mode is activated. Therefore, the engine can be stopped, and the EV mode can be activated (S150). In response to determining that the predicted cooling water temperature T Final is a low cooling water temperature, entry into the EV mode can be delayed, and it can be determined whether the vehicle is capable of traveling in the parallel HEV mode (S160). Generally, the vehicle is capable of traveling in the parallel HEV mode when the vehicle travels at a predetermined speed or higher.

[0077] When the vehicle is capable of traveling in the parallel HEV mode, the parallel HEV mode can be maintained (S170). The process returns to step S120 to predict the duration of the EV mode. When the vehicle is not capable of traveling in the parallel HEV mode, the series HEV mode can be maintained (S180). The process returns to step S120 to predict the duration of the EV mode.

[0078] As described above, in the first example embodiment of the present disclosure, when switching to the EV mode is requested, the predicted cooling water temperature T Final may be calculated based on traffic signal information before the engine is stopped, and it can be determined whether the predicted cooling water temperature T Final is a low cooling water temperature. In response to determining that the predicted cooling water temperature T Final is a low cooling water temperature, the HEV mode can be maintained, and in response to determining that the predicted cooling water temperature T Final is sufficiently high, the travel mode can be switched to the EV mode. Therefore, when the vehicle is stopped or travels at a low speed due to a traffic signal, a decrease in fuel efficiency due to entry into the series HEV mode for adjusting the cooling water temperature according to a request by the FATC unit can be prevented.

[0079] Figure 8 is a flowchart showing a control process of a hybrid vehicle according to a second example embodiment of the present disclosure. Specifically, Figure 8 an example embodiment in which heating performance is reduced to minimize operation in the series HEV mode is shown. Referring to Figure 8 , when switching to the EV mode is requested (S210), the duration of the EV mode can be predicted based on traffic signal information (S220). The duration of the EV mode can be predicted by calculating the time t1 taken for the vehicle to decelerate and reach the traffic signal, and the signal waiting time t2 remaining until the travel signal of the traffic signal, e.g., the green light, is turned on.

[0080] When the duration of the EV mode is predicted, the temperature change of the cooling water can be predicted (S230). The predicted cooling water temperature T initial can be calculated by reflecting the change in heat during the EV mode in the initial cooling water temperature T Final . Thereafter, it can be determined whether the calculated predicted cooling water temperature T Final is a low cooling water temperature, which is equal to or lower than a first reference value (FATC ON temperature) required for the FATC unit to perform indoor heating (S240).

[0081] In response to determining that the predicted cooling water temperature T Final is not a low cooling water temperature, the temperature of the engine cooling water is sufficient to maintain indoor heating even if the EV mode is activated. Accordingly, the engine can be stopped, and the EV mode can be activated (S280). In response to determining that the predicted cooling water temperature T Final is a low cooling water temperature in step S240, entry into the EV mode can be delayed, and a request for reducing the heating performance can be made to the FATC unit (S250). In other words, a request for reducing the reference temperature of the cooling water required for indoor heating or reducing the heating temperature can be transmitted.

[0082] When it is not possible to reduce the heating performance of the FATC unit, the engine can be stopped and the EV mode can be activated (S280). When it is possible to reduce the heating performance of the FATC unit (S260), the reference temperature of the cooling water or the heating temperature can be adjusted to reduce the heating performance (S270). The process returns to step S220 to predict the duration of the EV mode.

[0083] As described above, in the second exemplary embodiment of the present disclosure, when a request to switch to the EV mode is made, the predicted cooling water temperature T Final can be calculated based on traffic signal information before the engine is stopped, and it can be determined whether the predicted cooling water temperature T Final is a low cooling water temperature. In response to determining that the predicted cooling water temperature T Final is a low cooling water temperature, the heating performance can be reduced, thereby preventing a reduction in fuel efficiency due to entry into the series HEV mode for adjusting the cooling water temperature according to the request of the FATC unit.

[0084] The control procedure according to the exemplary embodiment of the present disclosure can be implemented such that the hybrid control unit acquires traffic signal information from the AVN system and executes a program pre-stored in an internal memory to predict a duration of the EV mode or estimate a cooling water temperature. In addition, a heating setting can be acquired from an air conditioning controller (e.g., a FATC unit). In addition, information on a current cooling water temperature can be acquired from an engine controller, and a request to start the engine can be executed in the form of transmitting a command to the engine controller. According to another aspect of the exemplary embodiment, the engine controller can be configured to execute the above-described control logic, or a separate controller can be provided to execute the control logic.

[0085] Figure 9 A graph for illustrating an effect of HEV mode switching for indoor heating in a hybrid vehicle of the present disclosure is shown. Figure 9 A vehicle speed graph, a graph showing a change in a value of an accelerator position sensor (APS), a travel mode graph, and a cooling water temperature graph are shown. The horizontal axis of each of these graphs represents time.

[0086] The first interval S1 is an interval in which the vehicle travels at a speed at which the vehicle can travel in a parallel mode. In the parallel mode, power of the engine is used as a driving force, so the temperature of the engine cooling water can increase due to heat of the engine. As the parallel mode travel time increases, the temperature of the cooling water increases, and the engine cooling water whose temperature is higher than a reference temperature can be used as an energy source for indoor heating.

[0087] The second interval S2 is a deceleration interval in which the vehicle decelerates and travels to a traffic signal. If the driver stops operating the accelerator pedal to decelerate, the speed of the vehicle decreases. Conventionally, when the speed of the vehicle decreases, the engine is stopped to enter the EV mode, and the temperature of the cooling water decreases from the time at which the EV mode is activated. However, the present disclosure predicts a duration of the EV mode based on the traffic signal information, and predicts a temperature change of the cooling water based on the duration of the EV mode.

[0088] In response to determining that the predicted cooling water temperature T Final is a low cooling water temperature equal to or lower than a first reference value (FATC ON temperature) required for the FATC unit to perform indoor heating, entry into the EV mode can be delayed, and the parallel HEV mode can be maintained. Accordingly, the temperature of the cooling water continues to increase. The present disclosure can predict a duration of the EV mode and predict a temperature change of the cooling water based on the duration of the EV mode in a state in which the parallel HEV mode is maintained. In response to determining that the predicted cooling water temperature T FinalInstead of the low cooling water temperature, the engine can be stopped, and the EV mode can be activated. The temperature of the cooling water decreases from the time when the EV mode is activated.

[0089] The third interval S3 and the fourth interval S4 are intervals in which the vehicle waits for a signal of a traffic signal light to be changed to a traveling signal. Conventionally, since the temperature of the cooling water decreases to the low cooling water temperature while the vehicle waits for the traffic signal, the FATC unit requests the engine to be driven. Accordingly, the HCU enters the series HEV mode to increase the temperature of the cooling water. In contrast, according to the present disclosure, based on the signal waiting time, it is possible to maintain the parallel HEV mode until the temperature of the cooling water is sufficiently increased, and then the EV mode can be activated, thereby preventing the temperature of the cooling water from decreasing to the low cooling water temperature while the vehicle waits for the traffic signal. Accordingly, it is possible to maintain the EV mode while the vehicle waits for the traffic signal.

[0090] The fifth interval S5 is an interval in which the vehicle resumes traveling in response to the traveling signal of the traffic signal light and travels at a speed at which the vehicle can travel in the parallel mode. As described above, the present disclosure can minimize the operation in the series HEV mode for indoor heating when the vehicle travels at a low speed or stops due to, for example, the traffic signal light.

[0091] The present disclosure can be implemented as a code that can be recorded on a non-transitory computer-readable recording medium and can be read by a computer system. The non-transitory computer-readable recording medium includes all types of recording devices in which data that can be read by a computer system is stored. Examples of the computer-readable recording medium include a hard disk drive (HDD), a solid state disk (SSD), a silicon disk drive (SDD), a read-only memory (ROM), a random access memory (RAM), a compact disk ROM (CD-ROM), a magnetic tape, a floppy disk, and an optical data storage device.

[0092] As apparent from the above description, the hybrid vehicle according to at least one exemplary embodiment of the present disclosure configured as described above can minimize traveling in the series HEV mode under a traveling condition in which indoor heating is required, thereby improving fuel efficiency. In particular, the duration of the EV mode and the change in the temperature of the cooling water are predicted using the traffic signal light information, based on which the time during which the vehicle travels in the parallel HEV mode is increased or the heating performance of the FATC unit is decreased, thereby minimizing traveling in the series HEV mode.

[0093] However, the effects obtainable through the present disclosure are not limited to the above-mentioned effects, and it will be clearly understood by persons skilled in the art from the foregoing description that other effects not mentioned herein will be included.

[0094] It will be obvious to those skilled in the art that various changes can be made without departing from the true spirit and scope of the disclosure set forth in this specification. The above detailed description is, therefore, not to be considered in a limiting sense as the scope of the disclosure is intended to be measured in the broadest practical sense of the following claims.

Claims

1. A control method of a hybrid vehicle, comprising: receiving, by a controller, traffic signal information including signal information and distance information of a front traffic signal, in an electric vehicle (EV) mode entry condition; predicting, by the controller, a duration of the EV mode, based on the received traffic signal information; predicting, by the controller, a cooling water temperature in the EV mode, according to the predicted duration of the EV mode; comparing, by the controller, the predicted cooling water temperature with a reference temperature at which a full automatic temperature control (FATC) unit requests an engine to be started; and entering, by the controller, the EV mode when the predicted cooling water temperature is higher than the reference temperature, wherein the cooling water temperature in the EV mode is predicted by adding a cooling water temperature that is decreased by heating when the engine is not operated for the predicted duration of the EV mode, to an initial cooling water temperature when the engine is operated, wherein a temperature change of the cooling water is calculated using heat received from the engine, heat discharged to the atmosphere, and heat used for indoor heating, wherein the temperature change of the cooling water (AT) is based on the following equation: where Q engine represents heat received from the engine, Q Out represents heat emitted to the atmosphere, Q Out = f (outside air temperature, engine cooling water temperature), Q Fatc represents heat used for indoor heating, Q Fatc = f (set temperature, indoor temperature), C represents the heat capacity of the engine cooling water, and M represents the mass of the engine cooling water.

2. The method of claim 1, further comprising: determining, by the controller, whether a first hybrid electric vehicle (HEV) mode using power of the engine as a driving force can be entered, when the predicted cooling water temperature is equal to or lower than the reference temperature; and entering, by the controller, the first HEV mode in response to determining that the first HEV mode can be entered.

3. The method of claim 2, further comprising: entering, by the controller, a second HEV mode in which the engine is used to generate power in response to determining that the first HEV mode cannot be entered.

4. The method of claim 3, wherein: the first HEV mode includes a parallel mode, and the second HEV mode includes a series mode.

5. The method of claim 1, further comprising: requesting, by the controller, the FATC unit to decrease at least one of the reference temperature or a heating set temperature in response to determining that the predicted cooling water temperature is equal to or lower than the reference temperature.

6. The method of claim 1, wherein: the receiving the traffic signal information includes receiving at least one of a signal change period of the front traffic signal, a currently displayed signal ahead of a current route, a remaining distance to the front traffic signal, a remaining time of the currently displayed signal, next signal display information, or traffic signal location information.

7. The method of claim 1, wherein: the predicting the duration of the EV mode based on the received traffic signal information includes calculating a sum of a time taken for a vehicle to decelerate and arrive at the traffic signal based on the traffic signal information, and a signal waiting time remaining until a signal of the traffic signal is turned on.

8. The method of claim 7, wherein: The predicting the duration of the EV mode based on the received traffic signal information includes calculating the signal wait time using a current signal, a remaining time of the current signal, a next signal, and a remaining time of the next signal.

9. A non-transitory computer-readable recording medium having recorded thereon a program for executing the control method of the hybrid vehicle according to claim 1.

10. A hybrid vehicle comprising: a first controller configured to receive traffic signal information including signal information and distance information of a traffic signal ahead; and a second controller configured to predict a duration of an electric vehicle mode (EV mode) based on the received traffic signal information, predict a cooling water temperature in the EV mode according to the predicted duration of the EV mode, compare the predicted cooling water temperature with a reference temperature at which a full automatic temperature control (FATC) unit requests starting of an engine, and enter the EV mode when the predicted cooling water temperature is higher than the reference temperature, wherein the second controller predicts the cooling water temperature in the EV mode by adding a cooling water temperature decreased by heating when the engine is not operated for the predicted duration of the EV mode to an initial cooling water temperature when the engine is operated, wherein a temperature change of the cooling water is calculated using heat received from the engine, heat emitted to the atmosphere, and heat used for indoor heating, wherein the temperature change of the cooling water (AT) is based on the following equation: where Q engine represents heat received from the engine, Q Out represents heat emitted to the atmosphere, Q Out = f (outside air temperature, engine cooling water temperature), Q Fatc represents heat used for indoor heating, Q Fatc = f (set temperature, indoor temperature), C represents the heat capacity of the engine cooling water, and M represents the mass of the engine cooling water.

11. The hybrid vehicle according to claim 10, wherein the second controller is configured to determine whether a first hybrid electric vehicle (HEV) mode using power of the engine as a driving force can be entered in response to determining that the predicted cooling water temperature is equal to or lower than the reference temperature, and enter the first HEV mode in response to determining that the first HEV mode can be entered.

12. The hybrid vehicle according to claim 11, wherein the second controller is configured to enter a second HEV mode in which the engine is used to generate power in response to determining that the first HEV mode cannot be entered.

13. The hybrid vehicle according to claim 10, wherein the FATC unit is configured to perform indoor heating using the cooling water, and request the second controller to start the engine in response to determining that the cooling water temperature is equal to or lower than the reference temperature.

14. The hybrid vehicle according to claim 13, wherein the second controller is configured to request the FATC unit to decrease at least one of the reference temperature or a heating set temperature in response to determining that the predicted cooling water temperature is equal to or lower than the reference temperature.

15. The hybrid vehicle according to claim 10, wherein The traffic signal information includes at least one of a signal change period of a front traffic signal, a currently displayed signal in front of a current route, a remaining distance to the front traffic signal, a remaining time of the currently displayed signal, next signal display information, or traffic signal position information.

16. The hybrid vehicle according to claim 10, wherein The second controller is configured to predict a duration of the EV mode by calculating a sum of a time taken for the vehicle to decelerate and reach the traffic signal based on the traffic signal information and a signal waiting time remaining until a signal of the traffic signal is turned on.

17. The hybrid vehicle according to claim 16, wherein The second controller is configured to calculate the signal waiting time using a current signal, a remaining time of the current signal, a next signal, and a remaining time of the next signal.

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