Hybrid Electric Vehicle and Engine Operation Control Method Therefor

Abstract

An engine operation control method for a hybrid electric vehicle includes determining a necessity for warm up control for an engine, determining a time required for the warm up control upon determining that the warm up control is necessary, predicting driving conditions in a predetermined forward range, determining a time or a point at which driving power of the engine is required in the predicted driving conditions, determining a control start time or a control start point to complete the warm up control before arrival at the determined time or point at which the driving power of the engine is required based on the determined time required for the warm up control, and starting the warm up control upon arrival at the control start time or the control start point.

Claims

1. An engine operation control method for a hybrid electric vehicle, the method comprising: determining a necessity for warm up control for an engine; determining a time required for the warm up control upon determining that the warm up control is necessary; predicting driving conditions in a predetermined forward range; determining a time or a point at which driving power of the engine is required in the predicted driving conditions; determining a control start time or a control start point to complete the warm up control before arrival at the determined time or point at which the driving power of the engine is required based on the determined time required for the warm up control; and starting the warm up control upon arrival at the control start time or the control start point.

2. The method according to claim 1, further comprising stopping the engine and driving using only a motor before the control start time or the control start point.

3. The method according to claim 1, wherein predicting the driving conditions is performed based on at least one expected route estimated using at least one of a departure date, time, driving statistical data of each driver, a navigation set route, and electronic diary based schedule information.

4. The method according to claim 3, wherein predicting the driving conditions is performed based on at least one of an average speed and an acceleration correction value according to road types, speed limits, gradients, degrees of congestion, and driver characteristics of each of the at least one expected route.

5. The method according to claim 3, wherein determining the control start time or the control start point comprises: when there is a plurality of expected routes, determining control start times or control start points for each of the expected routes; and selecting a first arriving control start time or a first arriving control start point from the control start times or the control start points for the plurality of expected routes.

6. The method according to claim 1, wherein determining the control start time or the control start point comprises: converting the determined time required for warm up control into a distance requiring warm up control based on an average speed until the determined time or point at which the driving power of the engine is required; and determining a point preceding the determined point at which the driving power of the engine is required by the distance requiring the warm up control as the control start point.

7. The method according to claim 1, wherein determining the time or the point at which the driving power of the engine is required is performed in consideration of limit load of a motor.

8. A non-transitory computer-readable recording medium storing a program for executing the engine operation control method for the hybrid electric vehicle according to claim 1.

9. An engine operation control method for a hybrid electric vehicle, the method comprising: determining a necessity for warm up control for an engine; determining whether a current position corresponds to a specific zone upon determining that the warm up control is necessary; determining whether driving power of the engine is required until the hybrid electric vehicle exits the specific zone when the current position corresponds to the specific zone; performing the warm up control after the hybrid electric vehicle exits the specific zone when the driving power of the engine is not required in the specific zone; and performing the warm up control before arrival at a time or a point at which the driving power of the engine is required when the driving power of the engine is required in the specific zone.

10. The method according to claim 9, wherein the specific zone includes a zone in which exhaust gas emission reduction is enforced or recommended.

11. A hybrid electric vehicle, comprising: an engine control unit configured to determine a time required for warm up control for an engine when the warm up control is necessary; a driving pattern storage unit configured to predict driving conditions in a predetermined forward range; and a hybrid controller unit configured to determine a time or a point at which driving power of the engine is required in the predicted driving conditions, determine a control start time or a control start point to complete the warm up control before arrival at the determined time or point at which the driving power of the engine is required based on the time required for the warm up control, and control the warm up control to be executed upon arrival at the control start time or the control start point.

12. The hybrid electric vehicle according to claim 11, wherein the hybrid controller unit is configured to control the engine to be stopped and control the hybrid electric vehicle to travel using only a motor before the control start time or the control start point.

13. The hybrid electric vehicle according to claim 11, wherein the driving pattern storage unit is configured to predict the driving conditions based on at least one expected route estimated using at least one of a departure date, time, driving statistical data of each driver, a navigation set route, and electronic diary based schedule information.

14. The hybrid electric vehicle according to claim 13, wherein the driving pattern storage unit is configured to predict the driving conditions based on at least one of an average speed and an acceleration correction value according to road types, speed limits, gradients, degrees of congestion, and driver characteristics of each of the at least one expected route.

15. The hybrid electric vehicle according to claim 13, wherein, when there is a plurality of expected routes, the hybrid controller unit is configured to determine control start times or control start points for each of the expected routes and select a first arriving control start time or a first arriving control start point from the control start times or the control start points for the plurality of expected routes.

16. The hybrid electric vehicle according to claim 11, wherein the hybrid controller unit is configured to convert the time required for warm up control into a distance requiring warm up control based on an average speed until the time or point at which the driving power of the engine is required and determine a point before the determined point at which the driving power of the engine is required by the distance requiring the warm up control as the control start point.

17. The hybrid electric vehicle according to claim 11, wherein the hybrid controller unit is configured to determine the time or the point at which the driving power of the engine is required in consideration of limit load of a motor.

18. A hybrid electric vehicle, comprising: an engine control unit configured to determine necessity for warm up control for an engine; and a hybrid controller unit configured to determine whether a current position corresponds to a specific zone upon determining that the warm up control is necessary, determine whether driving power of the engine is required until the hybrid electric vehicle exits the specific zone when the current position corresponds to the specific zone, control the warm up control to be executed after the hybrid electric vehicle exits the specific zone when the driving power of the engine is not required in the specific zone, and control the warm up control to be executed before arrival at a time or a point at which the driving power of the engine is required when the driving power of the engine is required in the specific zone.

19. The hybrid electric vehicle according to claim 18, wherein the specific zone includes a zone in which exhaust gas emission reduction is enforced or recommended.

20. The hybrid electric vehicle according to claim 18, wherein the warm up control has characteristics related to temperature increase in at least one of coolant temperature, oil temperature and catalyst temperature of the engine.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0024] FIGS. 1A and 1B are diagrams for describing a problem when a vehicle starts to travel in a green zone.

[0025] FIG. 2 illustrates an example of a powertrain structure of a hybrid electric vehicle to which embodiments of the present invention are applicable.

[0026] FIG. 3 is a block diagram illustrating an example of a control system of the hybrid electric vehicle to which embodiments of the present invention are applicable.

[0027] FIG. 4 is a block diagram illustrating an example of a vehicle structure for performing engine operation control according to an embodiment of the present invention.

[0028] FIGS. 5A to 5E are diagrams for describing an engine operation control process according to an embodiment of the present invention.

[0029] FIG. 6 is a flowchart illustrating an example of a process of performing engine operation control according to an embodiment of the present invention.

[0030] FIG. 7 is a diagram for describing effects of engine operation control according to an embodiment of the present invention.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

[0031] The detailed description of the exemplary embodiments of the present invention will be given to enable those skilled in the art to implement and practice the invention with reference to the attached drawings. However, the present invention can be implemented in various different forms and is not limited to embodiments described herein. In addition, parts that are not related to the description will be omitted for clear description in the drawings, and the same reference numbers will be used throughout this specification to refer to the same or like parts.

[0032] Throughout the specification, when it is said that some part “includes” a specific element, this means that the part may further include other elements, not excluding the same, unless mentioned otherwise. In addition, parts denoted by the same reference numeral refer to the same component throughout the specification.

[0033] In embodiments of the present invention, a method for determining a point or a time at which an engine needs to be actively used on the basis of driving load of a predicted driving route and completing warm up control before arrival at the point or time is proposed.

[0034] Prior to description of an engine operation control method according to embodiments of the present invention, a structure and a control system of a hybrid electric vehicle according to embodiments, and the concept of a zone affected by exhaust gas emission, will be described.

[0035] FIG. 2 illustrates an example of a powertrain structure of a hybrid electric vehicle to which embodiments of the present invention are applicable.

[0036] FIG. 2 illustrates a powertrain of a hybrid electric vehicle employing a parallel type hybrid system in which an electric motor (or a drive motor) 140 and an engine clutch (EC) 130 are provided between an internal combustion engine (ICE) 110 and a transmission 150.

[0037] In this vehicle, when a driver depresses an accelerator pedal after starting, the motor 140 operates using battery power in a state in which the engine clutch 130 is opened and the power of the motor is transmitted to the transmission 150 and a final drive (FD) 160 to move wheels (i.e., EV mode). When the vehicle requires higher driving power due to gradually increasing speed, an auxiliary motor (or starter generator 120) can operate to drive the engine 110.

[0038] When the rotation speed of the engine 110 becomes identical to the rotation speed of the motor 140, the engine clutch 130 is engaged such that the engine 110 and the motor 140 drive the vehicle together or the engine 110 drives the vehicle (i.e., transition from the EV mode to an HEV mode). When predetermined engine off conditions including vehicle speed reduction are satisfied, the engine clutch 130 is opened and the engine 110 stops (i.e., transition from the HEV mode to the EV mode). Further, in the hybrid electric vehicle, the driving power of the wheels can be converted into electric energy during braking to charge a battery, which is referred to as braking energy regeneration or regenerative braking.

[0039] The starter generator 120 serves as a starter motor when the engine is started and serves as a generator after the engine is started or rotation energy of the engine is recovered when the engine is turned off, and thus may be referred to as a “hybrid starter generator (HSG)”. The starter generator 120 may also be referred to as an “auxiliary motor” as necessary.

[0040] Correlation between control units in a vehicle to which the above-described powertrain is applied is illustrated in FIG. 3.

[0041] FIG. 3 is a block diagram illustrating an example of a control system of a hybrid electric vehicle to which embodiments of the present invention are applicable.

[0042] Referring to FIG. 3, in the hybrid electric vehicle to which embodiments of the present invention are applicable, the internal combustion engine 110 may be controlled by an engine control unit 210, torques of the starter generator 120 and the electric motor 140 may be controlled by a motor control unit (MCU) 220, and the engine clutch 130 may be controlled by a clutch control unit 230. Here, the engine control unit 210 may also be called an engine management system (EMS). Further, the transmission 150 is controlled by a transmission control unit 250. A control unit for the starter generator 120 and a control unit for the electric motor 140 may be separately provided as necessary.

[0043] Each control unit may be connected to a hybrid controller unit 240 which is a higher control unit and controls a mode switching process and may provide information necessary to change driving modes and to control the engine clutch during gear shifting and/or information necessary for engine stop control to the control units under the control of the hybrid controller unit 240 or perform an operation according to a control signal.

[0044] More specifically, the hybrid controller unit 240 determines whether to perform mode switching according to a driving state of the vehicle. For example, the hybrid controller unit 240 determines an open time of the engine clutch 130 and performs hydraulic control (in the case of a wet engine clutch) or torque capacity control (in the case of a dry EC) when the engine clutch 130 is opened. Further, the hybrid controller unit 240 may determine a state (lock-up, slip, open, or the like) of the engine clutch 130 and control a fuel injection stop time of the engine no. Further, the hybrid controller unit may transmit a torque command for controlling the torque of the starter generator 120 for engine stop control to the motor control unit 220 to control recovery of engine rotation energy. In addition, the hybrid controller unit 240 can control lower control units for engine operation control and mode switching control according to embodiments of the present invention which will be described later.

[0045] The above-described correlation between control units and the function/definition of each control unit are exemplary and it is obvious to those skilled in the art that the control units are not limited by the names thereof. For example, the hybrid controller unit 240 may be realized such that any one of other control units provides the functions of the hybrid controller unit 240 or two or more other control units may provide the functions in a distributed manner.

[0046] Next, the concept of a green zone will be described.

[0047] A green zone may be an engine operation restriction area in which exhaust gas emission is regulated for the purpose of improving the atmospheric environment for pedestrians. The green zone may be a preset area or may be variably set according to a current/recent situation. Here, a preset area may correspond to an area set by regulations or government policy (e.g., an exhaust gas management area of London or Seoul), an area where exhaust gas reduction is necessary due to regional characteristics (e.g., a child protection zone, an indoor parking lot, a residential area, a park, a drive-through, a hospital, etc.), and the like. In addition, a variably set area may correspond to an area in which current settings can be checked through RF information such as telematics, a pedestrian-concentrated area determined through a vision information acquisition device (ADAS system or the like) included in a vehicle, and the like. Specifically, a specific area in which an atmospheric condition determined to deteriorate with reference to atmospheric environment information, an area determined to be a pedestrian-concentrated area on the basis of big data using position information of a smartphone, and an area in which a large amount of exhaust gases is estimated to be generated on the basis of vehicle average speeds and traffic collected through a telematics service may correspond to variably set areas.

[0048] Furthermore, an area affected by exhaust gas emission may be set in units of an arbitrary administrative district, set as a zone connecting a plurality of coordinates that are boundary points, or set as a specific facility/part thereof or a zone within a specific radial distance from specific facility/coordinates.

[0049] The above-described examples are exemplary and embodiments of the present invention are not limited to setting criteria, setting ranges and setting periods of such areas.

[0050] Next, a vehicle configuration for performing engine operation control according to an embodiment will be described with reference to FIG. 4.

[0051] FIG. 4 is a block diagram illustrating an example of a vehicle configuration for performing engine operation control according to an embodiment of the present invention.

[0052] Referring to FIG. 4, for engine operation control according to an embodiment, a hybrid electric vehicle may include the engine control unit 210, the hybrid controller unit 240, a navigation system 260, and a driving pattern storage unit 270. The configuration illustrated in FIG. 4 shows components related to engine operation control, and it is obvious to those skilled in the art that the hybrid electric vehicle may further include the components illustrated in FIGS. 2 and 3 in actual implementation. Hereinafter, the operation of each component will be described in detail with reference to FIGS. 5A to 5E as necessary. FIGS. 5A to 5E are diagrams for describing an engine operation control process according to an embodiment of the present invention.

[0053] First, the engine control unit 210 can predict a time required for temperature increase control, that is, catalyst heating (CH) and warm-up (Wup), through modeling with respect to temperature increase control related characteristics. To this end, the engine control unit 210 may use at least one state factor related to temperature increases, such as outside air temperature, coolant temperature, oil temperature, batch catalyst temperature and soaking time. For example, when coolant temperature is used, the engine control unit 210 can use a catalyst heating time (CH time) graph according to coolant temperature or a table corresponding thereto.

[0054] The driving pattern storage unit 270 can predict an expected route after engine start. For an expected route, expected route candidates can be determined by detecting branch points within a specific distance from a start point and using a departure date/time/statistical data for each driver, a route set by a driver, digital library based schedule information, and the like, as illustrated in FIG. 5B. If there is no or insufficient information necessary for route prediction, all route branch points may be set as route candidates.

[0055] In addition, the driving pattern storage unit 270 can classify driving routes into a plurality of classes according to average speeds and acceleration on the basis of road information such as road types, speed limits, and degrees of congestion and store a correction value to be applied to a speed/acceleration per class depending on the driver's driving style, as illustrated in FIG. 5C. In other words, the driving pattern storage unit 270 can cumulatively learn correction values appearing when the corresponding driver drives the vehicle along a route corresponding to a specific class.

[0056] The hybrid controller unit 240 may include an on-route required load prediction unit 241, an engine temperature increase control time determination unit 242, and a driving mode determination unit 243.

[0057] The on-route required load prediction unit 241 can predict driving load profiles by reflecting driver correction values of the driving pattern storage unit 270 in average load on the basis of map information and traffic information of the navigation system 260 for each expected route candidate, as illustrated in FIG. 5D. Here, when route 1 and route 2 are the same route before branch point 2, as shown in FIG. 5D, calculation with respect to a section in which expected load has been calculated may be omitted for one route (e.g., route 1).

[0058] The engine temperature increase control time determination unit 242 can convert a time necessary for temperature increase, predicted by the engine control unit 210, into a distance on the basis of a predicted vehicle speed (i.e., an average speed until a time or a point at which the driving power of the engine is required) of each expected route candidate and set a temperature increase control section such that temperature increase control can be completed immediately before expected load for each route reaches load that requires engine operation (i.e., EV limit load). Here, “immediately before” may mean that a distance or a time interval between a point/time at which temperature increase control is completed and a point/time at which engine operation is required is within a predetermined distance or time (e.g., 100 m or 10 seconds).

[0059] Here, in a case where temperature increase control section start times/points are different for respective expected routes, execution of temperature increase control may be determined on the basis of a temperature increase control section that starts first. This will be described with reference to FIG. 5E.

[0060] Referring to FIG. 5E, an EV limit load point 520 of route 2 arrives prior to an EV limit load point 530 of route 1, and thus a temperature increase control section of route 2 starts first. In this case, the engine temperature increase control time determination unit 242 can determine execution of temperature increase control on the basis of a point 510 that precedes the EV limit load point 520 of route 2 by a distance necessary for temperature increase control, that is, the temperature increase control section start point 510 of route 2.

[0061] Thereafter, upon arrival at a temperature increase control start point/time with reference to the navigation system 260, the engine temperature increase control time determination unit 242 can notify the driving mode determination unit 243 of switching to the HEV mode and notify the engine control unit 210 of permission for temperature increase control. Accordingly, the engine control unit 210 can increase the temperature of the engine no through idle control or the like.

[0062] The engine operation control process according to the above-described embodiment is arranged as a flowchart in FIG. 6.

[0063] FIG. 6 is a flowchart illustrating an example of a process of performing engine operation control according to an embodiment of the present invention.

[0064] Referring to FIG. 6, the engine control unit 210 may determine whether engine warm-up is required on the basis of coolant temperature, oil temperature, and the like (S610) and estimate a time required for warm-up on the basis of engine modeling (S620).

[0065] The driving pattern storage unit 270 may provide expected routes and driving style information depending thereon to the hybrid controller unit 240, and the hybrid controller unit 240 may predict a time or a point at which the driving power of the engine is required by predicting required load for each expected route on the basis of forward driving conditions such as the expected routes, the driving style information, and traffic information (S630). Here, the forward driving conditions may include expected routes within a predetermined required time or a predetermined distance from a start point (or current position). Further, the traffic information may include road types, speed limits, gradients, degrees of congestion, and the like. The driving pattern storage unit 270 may be implemented in the form of a function or a module in the hybrid controller unit 240, implemented as a cloud server outside the vehicle, or implemented as a separate control unit for the corresponding function.

[0066] In addition, the hybrid controller unit 240 may determine temperature increase control start times at which temperature increase control can be completed before a time at which the driving power of the engine is required for respective expected routes in consideration of the time required for temperature increase at a point where the driving power of the engine is required and determine a control start time/point that starts first as a final temperature increase control start time/point (S640).

[0067] Subsequently, the hybrid controller unit 240 may check a current position, i.e., determine arrival at the control start time/point (S650), maintain the EV mode until arrival at the determined temperature increase control start time/point (S670), and switch the EV mode to the HEV mode and permit temperature increase control upon arrival at the determined temperature increase control start time/point (S660).

[0068] FIG. 7 is a diagram for describing effects of engine operation control according to an embodiment of the present invention.

[0069] Referring to FIG. 7, in a case where a general hybrid electric vehicle starts in a green zone, temperature increase control 710 is performed upon starting of the vehicle, and secondary temperature increase control 720 is performed when catalyst temperature increased through the temperature increase control 710 decreases to be lower than a criterion for temperature increase. As a result, temperature increase control is performed twice (710 and 720) before the hybrid electric vehicle exits the green zone, and temperature increased through secondary temperature increase control 720 may decrease according to natural cooling when the hybrid electric vehicle arrives at a zone having driving load exceeding the EV limit load, which is not desirable for efficiency or exhaust gas emission. However, according to an embodiment, engine temperature increase control 730 is performed once before the hybrid electric vehicle arrives at a zone having driving load exceeding the EV limit load, and thus it is possible to avoid a situation in which temperature increase control is unconditionally performed upon starting of the vehicle or temperature increase control is repeatedly performed.

[0070] Meanwhile, although a temperature control time or point has been determined on the basis of a time/point at which engine operation is required in the above-described embodiments, it may be determined whether to perform temperature increase control on the basis of whether a point at which engine operation is required is included in a green zone. For example, the hybrid controller unit 240 may determine whether an expected route until the vehicle exits a green zone includes a point at which engine operation is required when the current position of the vehicle is in the green zone and determine execution of temperature increase control after the vehicle exits the green zone when the expected route does not include a point at which engine operation is required. On the other hand, when the green zone includes a point at which engine operation is required, the engine operation control method according to the above-described embodiments can be used.

[0071] The above-described present invention can be realized as computer-readable code in a medium in which a program is recorded. Computer-readable media include all kinds of recording devices in which data readable by computer systems is stored. Examples of computer-readable media include a hard disk drive (HDD), a solid state drive (SSD), a silicon disk drive (SYD), a read-only memory (ROM), a random access memory (RAM), a compact disc read-only memory (CD-ROM), a magnetic tape, a floppy disk, an optical data storage device, etc.

[0072] Therefore, the above embodiments are therefore to be construed in all aspects as illustrative and not restrictive. The scope of the invention should be determined by the appended claims and their legal equivalents, not by the above description, and all changes coming within the meaning and equivalency range of the appended claims are intended to be embraced therein.

[0073] While this invention has been described with reference to illustrative embodiments, this description is not intended to be construed in a limiting sense. Various modifications and combinations of the illustrative embodiments, as well as other embodiments of the invention, will be apparent to persons skilled in the art upon reference to the description. It is therefore intended that the appended claims encompass any such modifications or embodiments.