Abstract:
A method for restart when Start-Stop Coasting (SSC) is released may include: determining whether a traveling vehicle satisfies a condition for releasing SSC after entry into SSC (S 100 ); determining whether emergency startup of the vehicle is required (S 200 ) when the traveling vehicle satisfies the condition for releasing SSC after entry into SSC; and performing a first startup process (S 300 ) in which a clutch ( 420 ) is engaged along with an operation of a starter motor ( 430 ) when the emergency startup of the vehicle is required.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority to and the benefit of Korean Patent Application No. 10-2015-0064530, filed on May 08, 2015, which is incorporated herein by reference in its entirety. 
       FIELD 
       [0002]    The present disclosure relates to a method and apparatus for restart when SSC is released. 
       BACKGROUND 
       [0003]    The statements in this section merely provide background information related to the present disclosure and may not constitute prior art. 
         [0004]    As the dissatisfaction of consumers is recently increased due to a difference between certified fuel efficiency and actual fuel efficiency when traveling on the road, an improvement of the actual fuel efficiency is increasingly important. Accordingly, technology for improving actual fuel efficiency when traveling on the road by using driving condition of a driver, surrounding traffic, road information, etc., as well as technology for controlling vehicle systems, has been researched and developed in vehicle industry. 
         [0005]    We have discovered that a technique of searching and guiding an economic driving route using IT and traffic information, a technique of guiding driving at high fuel efficiency by memorizing road gradient information and previous traveling patterns, a technique of controlling charge/discharge of a battery according to the SOC (state of charge) level thereof by predicting and determining road gradient and traffic information, and a technique of selectively controlling a traveling mode such that fuel consumption is reduced based on a destination route and traffic information by means of map information DB, are areas to be developed. 
         [0006]    One technique for improving the fuel efficiency is an SSC (Start-Stop Coasting) technique.  FIGS. 1A and 1B  are diagrams for explaining SSC. Referring to  FIGS. 1A and 1B , SSC is a technique of cutting off fuel supply to an engine (fuel cut) and cutting off power transfer to a transmission (clutch off) during coasting (see  FIG. 1A ). We have discovered that the mileage of a vehicle to which the SSC is applied is increased compared to that of the conventional vehicle since engine drag torque is cut off (see  FIG. 1B ). 
         [0007]    In the SSC of the related art, the engine is started by one selected from among a clutch and a starter motor when restart is performed after the SSC is released. When the stopped engine is started by the clutch, we have discovered that an impact is generated due to the rotating clutch coupled to the engine. For this reason, since unnecessary noise and vibration are caused during the restart in the related art, drivability and durability of relevant parts may be deteriorated. 
       SUMMARY 
       [0008]    The present disclosure provides a method and apparatus for restart when SSC is released, capable of rotating an engine by driving a starter motor for a short time before engagement of a clutch. 
         [0009]    The present disclosure can be understood by the following description, and become apparent with reference to the embodiments of the present disclosure. 
         [0010]    In accordance with the present disclosure, a method for restart when SSC is released includes: determining whether a traveling vehicle satisfies a condition for releasing SSC after entry into SSC (S 100 ); determining whether emergency startup of the vehicle is required (S 200 ) when the traveling vehicle satisfies the condition for releasing SSC after entry into SSC; and performing a first startup process (S 300 ) in which a clutch ( 420 ) is engaged along with an operation of a starter motor ( 430 ) when the emergency startup of the vehicle is required. 
         [0011]    The method may further include performing a second startup process (S 400 ) in which the clutch ( 420 ) is engaged without the operation of the starter motor ( 430 ) when the emergency startup of the vehicle is not required. 
         [0012]    The determining whether emergency startup of the vehicle is required (S 200 ) may include detecting an accelerator opening degree (S 210 ). 
         [0013]    The determining whether emergency startup of the vehicle is required (S 200 ) may include determining whether the detected accelerator opening degree is equal to or greater than a predetermined accelerator opening degree (S 220 ). 
         [0014]    The performing a first startup process (S 300 ) may include performing a starter motor startup process (S 310 ) of operating the starter motor ( 430 ) to rotate a stopped engine ( 410 ) after entry into SSC. 
         [0015]    The performing a first startup process (S 300 ) may include performing a clutch engagement process (S 320 ) of operating the clutch ( 420 ) to couple the engine ( 410 ) and a transmission (T), which are decoupled from each other, after entry into SSC. 
         [0016]    In the performing a first startup process (S 300 ), the performing a starter motor startup process (S 310 ) and the performing a clutch engagement process (S 320 ) may be simultaneously carried out. 
         [0017]    In the performing a first startup process (S 300 ), the performing a starter motor startup process (S 310 ) and the performing a clutch engagement process (S 320 ) may be sequentially carried out. 
         [0018]    In the performing a starter motor startup process (S 310 ), the starter motor ( 430 ) may be operated for a predetermined time. 
         [0019]    In the performing a starter motor startup process (S 310 ), the starter motor ( 430 ) may be operated until the rotational speed of the engine ( 410 ) is a predetermined rotational speed. 
         [0020]    The predetermined rotational speed may be a rotational speed in a predetermined error range relative to the rotational speed of the transmission (T). 
         [0021]    In the performing a starter motor startup process (S 310 ), fuel may be injected into the engine ( 410 ). 
         [0022]    After the performing a starter motor startup process (S 310 ) is completed, fuel may be injected into the engine ( 410 ). 
         [0023]    In accordance with another aspect of the present disclosure, there is provided a storage medium storing the method for restart when SSC is released. 
         [0024]    In accordance with another aspect of the present disclosure, an apparatus for restart when SSC is released includes a storage medium ( 100 ), a detection unit ( 200 ) detecting an accelerator opening degree, a transmission rotational speed, and an engine rotational speed, and a control unit ( 300 ) determining whether emergency startup of a vehicle is required according to information detected by the detection unit ( 200 ) so as to control a unit to be controlled ( 400 ). 
         [0025]    The detection unit ( 200 ) may include an accelerator opening degree detection unit ( 210 ), a transmission rotational speed detection unit ( 220 ), and an engine rotational speed detection unit ( 230 ). 
         [0026]    The unit to be controlled ( 400 ) may include an engine ( 410 ) into which fuel is injected, a clutch ( 420 ) coupling or decoupling the engine ( 410 ) and a transmission (T), and a starter motor ( 430 ) rotating the engine ( 410 ). 
         [0027]    Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
     
    
     
       DRAWINGS 
         [0028]    In order that the disclosure may be well understood, there will now be described various forms thereof, given by way of example, reference being made to the accompanying drawings, in which: 
           [0029]      FIGS. 1A and 1B  are diagrams for explaining SSC; 
           [0030]      FIGS. 2 to 5  are flowcharts illustrating a method for restart when SSC is released; and 
           [0031]      FIGS. 6 and 7  are block diagrams illustrating an apparatus for restart when SSC is released. 
       
    
    
       [0032]    The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way. 
       DETAILED DESCRIPTION 
       [0033]    The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features. 
         [0034]    On the basis of the principle that the inventor can define the appropriate concept of a term in order to describe his/her own present disclosure in the best way, it should be construed as meaning and concepts for complying with the technical idea of the present disclosure. Accordingly, the embodiments described in the present specification and the construction shown in the drawings are nothing but one form of the present disclosure, and it does not cover all the technical ideas of the present disclosure. Thus, it should be understood that various changes and modifications may be made at the time of filing the present application. In addition, detailed descriptions of functions and constructions well known in the art may be omitted to avoid unnecessarily obscuring the gist of the present disclosure. 
         [0035]    Referring to  FIGS. 2 to 5 , the method for restart when SSC is released according to the embodiment of the present disclosure includes a step S 100  of determining whether a traveling vehicle satisfies a condition for releasing SSC after entry into SSC, a step S 200  of determining whether emergency startup of the vehicle is required when the traveling vehicle satisfies the condition for releasing SSC after entry into SSC, and a step S 300  of performing a first startup process in which a clutch  420  is engaged along with an operation of a starter motor  430  when the emergency startup of the vehicle is required. In addition, the method for restart when SSC is released further includes a step S 400  of performing a second startup process in which the clutch  420  is engaged without the operation of the starter motor  430  when the emergency startup of the vehicle is not required. 
         [0036]    In the step S 100  of determining whether a traveling vehicle satisfies a condition for releasing SSC after entry into SSC, the condition of entry into SSC and the condition for releasing SSC may be differently set according to the type of vehicle. For example, the condition of entry into SSC may be a condition in which an accelerator pedal and a brake pedal are not operated and a vehicle speed is equal to or greater than a predetermined speed (herein, the predetermined speed may be differently set according to the type of vehicle). In addition, when the vehicle enters the SSC, fuel supply to an engine may be cut off (fuel cut) and power transfer to a transmission may be cut off (clutch off). In addition, the condition for releasing SSC may be a condition in which the accelerator pedal or the brake pedal is operated or the vehicle speed is less than a predetermined speed (herein, the predetermined speed may be differently set according to the type of vehicle). 
         [0037]    The step S 200  of determining whether emergency startup of the vehicle is required includes a step S 210  of detecting an accelerator opening degree (e.g. the degree of depression of the accelerator pedal), and a step S 220  of determining whether the detected accelerator opening degree is equal to or greater than a predetermined accelerator opening degree. That is, when the detected accelerator opening degree is equal to or greater than the predetermined accelerator opening degree, it is determined that a driver has an intention to rapidly accelerate, and thus it is determined that the emergency startup of the vehicle is required. The predetermined accelerator opening degree may be differently set according to the type of vehicle. 
         [0038]    The step S 300  of performing a first startup process includes a step S 310  of performing a starter motor startup process and a step S 320  of performing a clutch engagement process. The step S 310  of performing a starter motor startup process is a step of operating the starter motor  430  to rotate the stopped engine  410  after the entry into SSC. Since the clutch is decoupled (clutch off) and the fuel supply to the engine is cut off (fuel cut) after the entry into SSC, the engine is stopped. Accordingly, since the engine  410  is rotated by the starter motor  430  before the engagement of the clutch in the step S 310  of performing a starter motor startup process, an impact due to the engagement of the clutch is reduced. 
         [0039]    The step S 320  of performing a clutch engagement process is a step of operating the clutch  420  to couple the engine  410  and a transmission T which are decoupled from each other after the entry into SSC. In the step S 320  of performing a clutch engagement process, the engine  410  is rotated by the starter motor  430 . In addition, since the clutch  420  is decoupled after the entry into SSC and the vehicle is coasted, wheels of the vehicle and the transmission T connected to the wheels are also rotated. Accordingly, since the rotational speed of the engine  410  is nearly similar to the rotational speed of the transmission T in the present disclosure, compared to the related art in which the engine  410  is stopped during the engagement of the clutch, the impact due to the engagement of the clutch is reduced. 
         [0040]    In the step S 300  of performing a first startup process, the step S 310  of performing a starter motor startup process and the step S 320  of performing a clutch engagement process may be simultaneously or sequentially carried out. When the step S 310  of performing a starter motor startup process and the step S 320  of performing a clutch engagement process are simultaneously carried out, the restart may more rapidly performed corresponding to the need of the emergency startup. In addition, when the step S 310  of performing a starter motor startup process and the step S 320  of performing a clutch engagement process are sequentially carried out, the impact due to the engagement of the clutch may be further reduced since the clutch is engaged after the rotational speed of the engine is fully secured. 
         [0041]    In the step S 310  of performing a starter motor startup process, the starter motor  430  may be operated for a predetermined time. That is, the durability of the starter motor  430  may be secured by minimizing the operation time of the relatively expensive starter motor  430 . The predetermined time may be differently set according to the type of starter motor or the type of vehicle. 
         [0042]    In the step S 310  of performing a starter motor startup process, the starter motor  430  may be operated until the rotational speed of the engine  410  is a predetermined rotational speed. The predetermined rotational speed may be differently set according to the type of vehicle. In addition, the predetermined rotational speed may be set to be a rotational speed in a predetermined error range relative to the rotational speed of the transmission T. That is, the starter motor  430  may be operated until the predetermined rotational speed is in an error range in which the upper limit or the lower limit is a predetermined (+) error or a predetermined (−) error of the rotational speed of the transmission T. Thus, since the starter motor is operated when the rotational speed of the engine is nearly similar to the rotational speed of the transmission, the clutch is engaged after the rotational speed of the engine is fully secured. Consequently, the impact due to the engagement of the clutch may be further reduced. 
         [0043]    In the method for restart when SSC is released, the fuel may be injected into the engine  410  in the step S 310  of performing a starter motor startup process, and the fuel may also be injected into the engine  410  after the step S 310  of performing a starter motor startup process is completed. That is, the fuel may be injected into the engine when the vehicle travels at high fuel efficiency according to the traveling state thereof. 
         [0044]      FIGS. 6 and 7  are block diagrams illustrating an apparatus for restart when SSC is released according to another embodiment of the present disclosure. Referring to  FIGS. 6 and 7 , the apparatus for restart when SSC is released includes a storage medium  100 , a detection unit  200 , a control unit  300 , and a unit to be controlled  400 . 
         [0045]    The detection unit  200  includes an accelerator opening degree detection unit  210 , a transmission rotational speed detection unit  220  (e.g. detecting the speed of the transmission output shaft or an intermediary shaft), and an engine rotational speed detection unit  230 , and detects an accelerator opening degree, a transmission rotational speed, and an engine rotational speed. 
         [0046]    The control unit  300  determines whether emergency startup of a vehicle is required according to information detected by the detection unit  200 , and then controls the unit to be controlled  400 . 
         [0047]    The unit to be controlled  400  includes an engine  410  into which fuel is injected, a clutch  420  which couples or decouples the engine  410  and a transmission T, and a starter motor  430  which rotates the engine  410 . 
         [0048]    In accordance with the present disclosure, it is possible to reduce an impact due to engagement of a clutch when restart is performed after release of SSC and thus to improve durability of relevant parts such as the clutch. 
         [0049]    While the present disclosure has been described with respect to the specific embodiments, it will be apparent to those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the present disclosure as defined in the following claims.