Abstract:
A hybrid power-train includes an input shaft connected to an engine and an output shaft disposed in parallel with the input shaft. A motor is connected to the input shaft and the output shaft. A drive mechanism connects the engine, the motor, and the output shaft. A plurality of clutches are operable for coupling and releasing, respectively, to perform a mode conversion.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is based on and claims the benefit of priority to Korean Patent Application No. 10-2014-0166513, filed on Nov. 26, 2014 in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference. 
     TECHNICAL FIELD 
     The present disclosure relates to a hybrid powertrain, and more particularly, to a hybrid powertrain capable of saving costs, improving efficiency, and effectively implementing various multi modes with one motor. 
     BACKGROUND 
     A hybrid vehicle is driven by combining two different power sources, for example, an engine torque by combusting fuel (fossil fuel such as gasoline) and a motor torque by battery power. 
     The hybrid vehicle uses an engine and an electric motor as an auxiliary power source to reduce exhaust gas and enhance fuel efficiency. Studies on the hybrid vehicle have been actively conducted to meet the demands of enhancing fuel efficiency and developing environmentally-friendly products. 
     The hybrid vehicle generally uses a motor having relatively low-speed torque characteristics at a low speed as a main power source and uses an engine having relatively high-speed torque characteristics at a high speed as a main power source. 
     Therefore, the hybrid vehicle stops the engine at a low speed section and operates the motor, and therefore improving fuel efficiency and reducing exhaust gas. 
       FIG. 1  is a diagram illustrating an example of a hybrid power-train according to the related art, which includes an engine  1 , a first motor MG 1 , and a second motor MG 2 . 
     The first motor MG 1  serves as a generator which generates power by a driving force of an engine  1 , and the second motor is directly connected to an output shaft  4  to implement an electric vehicle (EV) mode. 
     An input shaft  2  which is connected to the engine  1  is provided with an over drive clutch  3 . The over drive clutch  3  directly connects the input shaft  2  to the output shaft  4  to implement a high efficiency point operation of an engine at the time of the high speed driving of the vehicle and is in a released operation state at normal times. 
     According to the related art, since the second motor MG 2  is connected to the output shaft  4  via two pairs of gears, efficiency of the EV mode is increased, and thus, fuel efficiency of plug-in hybrid electric vehicle charge depleting (PHEV CD) is excellent. 
     However, as all the driving forces of the engine at the time of driving a vehicle in a hybrid electric vehicle (HEV) mode are transferred to the first motor MG 1  and are output via the second motor (MG 2 ) after the first motor MG 1  generates power, conversion losses of mechanical energy and electrical energy occur, and therefore, the fuel efficiency of plug-in hybrid electric vehicle charge sustaining (PHEV CS) significantly decreases. Further, since the two motors MG 1  and MG 2  are used, the hybrid power-train according to the related art is expensive. 
       FIG. 2  is a diagram illustrating another example of a hybrid power-train according to the related art, which includes an engine  1 , first and second planetary gear sets PG 1  and PG 2 , a first motor MG 1 , and a second motor MG 2 . 
     The first motor MG 1  as a generator is connected to the input shaft  2  of the engine  1  through the first planetary gear set PG 1  to receive a driving force of the engine  1 . 
     The second motor MG 2  is directly connected to the output shaft  4  through the second planetary gear set PG 2  and a pair of gears to implement the EV mode. 
     According to the related art of another example as described above, the driving force is transferred via the planetary gear set PG 1  and the two pairs of gear at the time of EV driving. Thus, transfer efficiency is relatively reduced and the driving force of the engine is branched through the planetary gear set PG 2 , and therefore, the energy conversion loss is reduced. However, a power generation operation is performed by using the first motor MG 1  and therefore the efficiency thereof is low. Further, since two motors such as the first and second motors MG 1  and MG 2  are used, the hybrid power-train according to the related art is expensive. 
     SUMMARY 
     The present disclosure has been made to solve the above-mentioned problems occurring in the prior art while advantages achieved by the prior art are maintained intact. 
     An aspect of the present disclosure provides a hybrid power-train capable of saving costs, improving efficiency, and minimizing a loss of transfer efficiency and effectively implementing various multi modes, such as a high-efficiency EV mode, a parallel HEV mode, a serial mode, and a direct connection mode, to meet various driving conditions, by applying one motor. 
     According to an exemplary embodiment of the present inventive concept, a hybrid power-train includes an input shaft connected to an engine and an output shaft disposed in parallel with the input shaft. A motor is connected to the input shaft and the output shaft. A drive mechanism connects the engine, the motor, and the output shaft. A plurality of clutches are operable for coupling and releasing, respectively, to perform a mode conversion. 
     The drive mechanism may have a first power transfer part drivably connecting the input shaft and the motor. A second power transfer part drivably connects the input shaft and the output shaft, and a third power transfer part drivably connects the motor and the output shaft. 
     The plurality of clutches may include a first clutch in the first power transfer part, a second clutch in the second power transfer part, and a third clutch in the third power transfer part. 
     According to another exemplary embodiment of the present inventive concept, a hybrid power-train includes an input shaft connected to an engine and an output shaft disposed in parallel with the input shaft. A motor is connected to the input shaft and the output shaft. A first transfer shaft is branched from the input shaft. A second transfer shaft is branched from the input shaft and installed in parallel with the first transfer shaft. A motor driving shaft connects the motor and the first transfer shaft. A third transfer shaft is drivably connected to the motor driving shaft. A first clutch is installed in the first transfer shaft. A second clutch is installed in the second transfer shaft. A third clutch is installed in the third transfer shaft. 
     The input shaft may have a branch drive part. A driving force of the input shaft may be transferred to the first and second transfer shaft by the branch drive part. 
     The first and second transfer shafts may be branched in parallel with the input shaft by the branch drive part. 
     The first transfer shaft may be connected to the motor driving shaft. 
     The second transfer shaft may be connected to the output shaft. 
     The third transfer shaft may be connected to the motor driving shaft and the output shaft. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other objects, features, and advantages of the present disclosure will be more apparent from the following detailed description taken in conjunction with the accompanying drawings. 
         FIG. 1  is a configuration diagram illustrating an example of a hybrid power-train according to the related art. 
         FIG. 2  is a configuration diagram illustrating another example of a hybrid power-train according to the related art. 
         FIG. 3  is a configuration diagram illustrating a hybrid power-train according to an exemplary embodiment of the present inventive concept. 
         FIG. 4  is a diagram illustrating a power transfer system in starting/N stage charging mode of the hybrid power-train according to the exemplary embodiment of the present inventive concept. 
         FIG. 5  is a diagram illustrating a power transfer system in EV/regenerative mode of the hybrid power-train according to the exemplary embodiment of the present inventive concept. 
         FIG. 6  is a diagram illustrating a power transfer system in an HEV mode (motor auxiliary power) of the hybrid power-train according to the exemplary embodiment of the present inventive concept. 
         FIG. 7  is a diagram illustrating the power transfer system in an HEV mode (charging state of a motor) of the hybrid power-train according to the exemplary embodiment of the present inventive concept. 
         FIG. 8  is a diagram illustrating a power transfer system in an engine direct connection mode of the hybrid power-train according to the exemplary embodiment of the present inventive concept. 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, embodiments of the present inventive concept will be described in detail with reference to the accompanying drawings. For reference, a size of components, a thickness of a line, and the like which are illustrated in the drawing referenced for describing exemplary embodiments may be slightly exaggerated for convenience of understanding. Further, terms used to describe the present disclosure are defined in consideration of functions in the present disclosure and therefore may be changed depending on a user, an intention an operator, a practice, and the like. Therefore, the definition of the terminologies should be construed based on the contents throughout the specification. 
     As illustrated in  FIG. 3 , a hybrid power-train according to an embodiment includes an input shaft  11  connected to an engine  10 , an output shaft  15  disposed to be parallel with the input shaft  11 , and a motor MG connected to the input shaft  11  and the output shaft  15 . A drive mechanism  20  is connected among the engine  10 , the motor MG, and the output shaft  15  and includes a plurality of clutches CL 1 , CL 2 , and CL 3  installed therein. 
     The input shaft  11  is installed in a train housing (not shown), and one side of the input shaft  11  is connected to the engine  10  to receive a driving force of the engine  10 . 
     Another side of the input shaft  11  is connected to the output shaft  15  and the motor MG via the drive mechanism  20 . 
     The output shaft  15  is disposed to be parallel with the input shaft  11  and drives a vehicle wheel (not shown) and the output shaft  15 . 
     The motor MG is connected to the input shaft  11  and the output shaft  15 . The motor MG serves as a generator generating power by the driving force of the engine  10  and serves as a motor generating the driving force and supplying the generated driving force to the output shaft  15 . 
     The drive mechanism  20  includes a first power transfer part drivably connecting between the input shaft  11  and the motor MG, a second power transfer part drivably connecting between the input shaft  11  and the output shaft  15  to transfer power therebetween, and a third power transfer part drivably connecting between the motor MG and the output shaft  15 . 
     The first power transfer part includes a first transfer shaft  21  which is branched from the input shaft  11  toward the motor MG. The second power transfer part includes a second transfer shaft  22  which is branched from the input shaft  11  toward the output shaft  15 . The third power transfer part has a third transfer shaft  23  which is disposed in parallel with the first and second transfer shafts  21  and  22  between the motor MG and the output shaft  15 . 
     The first transfer shaft  21  and the second transfer shaft  22  are parallel to each other, and in particular, the first transfer shaft  21  and the second transfer shaft  22  are branched in parallel with the input shaft  11  through a branch drive part  24 . 
     The branch drive part  24  is installed at the other side of the input shaft  11  and thus branches the driving force of the input shaft  11  to the first and second transfer shafts  21  and  22  to be driven. The branch drive part  24  may have various structures to appropriately branch the driving force of the input shaft  11  such as a gear drive mechanism, a chain drive mechanism, or the like. 
     A motor driving shaft  25  is connected between the motor MG and the first transfer shaft  21 . The motor driving shaft  25  is drivably connected to the first transfer shaft  21 , and the third transfer shaft  23  is drivably connected to the motor driving shaft  25 . 
     The first transfer shaft  21  has a first transfer gear  21   a , the motor driving shaft  25  has a first driving gear  25   a  and a second driving gear  25   b , the second transfer shaft  22  has a second transfer gear  22   a , and the third transfer shaft  23  has a third transfer gear  23   a  and a fourth transfer gear  23   b.    
     The first transfer shaft  21  is connected to the motor driving shaft  25  by a gear drive. That is, the first transfer gear  21   a  of the first transfer shaft  21  meshes with the first driving gear  25   a  of the motor driving shaft  25 , and thus, the first transfer shaft  21  and the motor driving shaft  25  are connected to each other to be mutually driven. As such, the drivable connection between the first transfer shaft  21  and the motor driving shaft  25  configures a first power transfer part. 
     The second transfer shaft  22  is connected to the output shaft  15  by the gear drive. That is, the second transfer gear  22   a  of the second transfer shaft  22  meshes with a driving gear  15   a  of the output shaft  15 , and thus, the second transfer shaft  22  and the output shaft  15  are connected to each other to be mutually driven, and the drivable connection between the second transfer shaft  22  and the output shaft  15  configures a second power transfer part. 
     The third transfer shaft  23  is connected to the motor driving shaft  25  and the output shaft  15  by the gear drive. That is, the fourth transfer gear  23   b  of the third transfer shaft  23  meshes with the second driving gear  25   b  of the motor driving shaft  25 , and thus, the third transfer shaft  23  and the motor driving shaft  25  are connected to each other to be mutually driven. The third transfer gear  23   a  of the third transfer shaft  23  meshes with the driving gear  15   a  of the output shaft  15 , and thus, the third transfer shaft  23  and the output shaft  15  are connected to each other to be mutually driven. The drivable connection among the motor driving shaft  25 , the third transfer shaft  23 , and the output shaft  15  configures the third power transfer part. 
     A first clutch CL 1  is installed in the middle of the first transfer shaft  21  and controls a power transfer between the engine  10  and the motor MG. 
     A second clutch CL 2  is installed in the middle of the second transfer shaft  22  and controls a power transfer between the engine  10  and the output shaft  15 . 
     A third clutch CL 3  is installed in the middle of the third transfer shaft  23  and controls a power transfer between the motor MG and the output shaft  15 . 
     The coupling and release operations of the plurality of clutches CL 1 , CL 2 , and CL 3  are performed selectively, and the plurality of clutches CL 1 , CL 2 , and CL 3  may effectively implement various multi modes such as a high efficiency EV mode, a parallel HEV mode, a serial mode, and a direct connection mode to meet various driving conditions. 
     The multi-mode state of the hybrid power-train according to the exemplary embodiment as described above will be described with reference to  FIGS. 4 to 8 . 
     For a starting/N-stage charging mode, as illustrated in  FIG. 4 , power is transferred between the motor MG and the engine  10  through the release operations of the second and third clutches CL 2  and CL 3  and the coupling operation of the first clutch CL 1  independent of a state of the vehicle. 
     In the case of an EV/regenerative mode, as illustrated in  FIG. 5 , the driving force of the motor MG is transferred to the output shaft  15  through the motor driving shaft  25  and the third transfer shaft  23  by the release operations of the first and second clutches CL 1  and CL 2  and the coupling operation of the third clutch CL 3 . 
     In the case of an HEV mode in which the motor MG is used as auxiliary power, as illustrated in  FIG. 6 , the driving force of the engine  10  is transferred to the output shaft  15  through the second transfer shaft  22  and the driving force of the motor MG is transferred to the output shaft  15  through the third transfer shaft  23 , by the release operation of the first clutch CL 1  and the coupling operations of the second and third clutches CL 2  and CL 3 . 
     In the case of the HEV mode in which the motor MG is charged, as illustrated in  FIG. 7 , the driving force of the engine  10  is transferred to the output shaft  15  through the second transfer shaft  22  and some of the driving force of the engine  10  is transferred to the motor MG through the first transfer shaft  21  and the motor driving shaft  25 , by the release operation of the third clutch CL 3  and the coupling operations of the first and second clutches CL 2  and CL 3 , thereby performing the power generation of the motor MG. 
     In the case of the direct connection mode of the engine, as illustrated in  FIG. 8 , the driving force of the engine  10  is transferred to the output shaft  15  through the second transfer shaft  22 , by the release operations of the first and third clutches CL 1  and CL 3  and the coupling operation of the second clutch CL 2 . 
     As described above, according to the present disclosure, it is possible to save costs, improve fuel efficiency, minimize the loss of transfer efficiency, and effectively implement various multi modes, such as a high-efficiency EV mode, a parallel HEV mode, a serial mode, and a direct connection mode, to meet various driving conditions, by applying one motor. 
     Further, according to the present disclosure, it is possible to effectively implement the starting and the motor charging and the like at the time of an N stage charging mode (starting of the engine and driving and power generation of the motor) and an HEV mode by the first clutch which is installed in the first power transfer part between the engine and the motor, effectively implement the HEV mode (transfer the driving force by the engine) and the like by the second clutch which is installed in the second power transfer part between the engine and the output shaft, and effectively implement the EV mode, the regenerative mode, the HEV mode, and the like by the third clutch which is installed in the third power transfer part between the motor and the shaft output. That is, it is possible to effectively implement various multi modes such as the high efficiency EV mode, the parallel HEV mode, the serial mode, and the direct connection mode through the coupling, release, and the like of the first to third clutches. 
     Hereinabove, the exemplary embodiments of the present inventive concept are described but the present disclosure is not limited to the disclosed embodiments and the accompanying drawings and may be variously changed without departing from the spirit and the scope of the present disclosure.