Abstract:
A planetary gear train of a transmission for a vehicle is provided. The planetary gear train includes an input shaft that receives power of an engine and an output shaft that outputs power. Multiple planetary gear sets are provided each having three rotation elements. Various shafts then either directly or selectively connect the rotation elements. The transmission is then capable of maximizing engine driving efficiency and improving a power delivery performance and fuel consumption.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority to and the benefit of Korean Patent Application No. 10-2016-0031661 filed in the Korean Intellectual Property Office on Mar. 16, 2016, the entire contents of which are incorporated herein by reference. 
       BACKGROUND 
       [0002]    (a) Field of the Invention 
         [0003]    The present invention relates to an automatic transmission for a vehicle, and more particularly, to a planetary gear train of an automatic transmission for a vehicle that improves a power delivery performance and enhances fuel consumption by implementing at least forward fourteen-speed with a minimal configuration and reduces running noise of the vehicle by using a driving point in a low rotation speed range of an engine. 
         [0004]    (b) Description of the Related Art 
         [0005]    In general, in an automatic transmission field, research has been conducted regarding a multistage of a gear shift stage to enhance fuel consumption of a vehicle and to maximize drivability thereof, and recently, increase of an oil price is triggering a competition in enhancing fuel consumption of the vehicle. Accordingly, research has been conducted for reducing a weight of an engine and enhancing fuel consumption thereof by downsizing of the engine, and in the automatic transmission, a research regarding technology that can simultaneously secure drivability and fuel consumption competitive power through a multistage of a gear shift stage has been conducted. 
         [0006]    However, in the automatic transmission, as a gear shift stage increases, the internal component number, particularly, the planetary gear set number increases and thus, a full length of the transmission increases and a mounting ability, a production cost, a weight, and power delivery efficiency may thus be worsened. Therefore, in the automatic transmission, to increase a fuel consumption enhancement effect suing a multistage of a gear shift stage, development of a planetary gear train that can induce maximum efficiency with a minimal number of components is important. 
         [0007]    Accordingly, an automatic transmission has been formed to implement a shift of 8-speed or more to be mounted within a vehicle, and research and development of a planetary gear train capable of implementing a gear shift stage of 8-speed or more has been continuously required. However, a general 8-speed or more of automatic transmission is often formed with three or four planetary gear sets and five or six control elements (friction element), and in this case, a full length of the system is extended and thus there is a drawback that a mounting ability is worsened. Accordingly, to form a gear shift stage of an automatic transmission in a multistage, a double row structure that disposes a planetary gear set on a planetary gear set has been adapted or a dog clutch has been applied instead of a wet control element. However, such a structure is limited and a shift feel is worsened due to application of the dog clutch. 
         [0008]    The above information disclosed in this section is merely for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art. 
       SUMMARY 
       [0009]    The present invention provides a planetary gear train of an automatic transmission for a vehicle having advantages of being capable of obtaining power delivery performance improvement and fuel consumption enhancement effects according to a multistage of a gear shift stage by implementing a gear shift stage of at least forward fourteen-speed or more and at least reverse one-speed or more with a minimal configuration and reducing running noise of the vehicle by using a driving point in a low rotation speed range of an engine. 
         [0010]    An exemplary embodiment of the present invention provides a planetary gear train of an automatic transmission for a vehicle that may include: an input shaft configured to receive power of an engine; an output shaft configured to output power; a first planetary gear set having first, second, and third rotation elements; a second planetary gear set having fourth, fifth, and sixth rotation elements; a third planetary gear set having seventh, eighth, and ninth rotation elements; a fourth planetary gear set having tenth, eleventh, and twelfth rotation elements; a first shaft that may connect the first rotation element and the fourth rotation element; a second shaft that may connect the second rotation element and the sixth rotation element; a third shaft that may be connected with the third rotation element; a fourth shaft that may be connected with the fifth rotation element and that may be directly connected with the input shaft; a fifth shaft that may be connected with the seventh rotation element and that may be selectively connected with the second shaft and the third shaft; a sixth shaft that may connect the eighth rotation element and the twelfth rotation element and that may be selectively connected with the third shaft and the fourth shaft; a seventh shaft that may connect the ninth rotation element and the eleventh rotation element and that may be directly connected with the output shaft; and an eighth shaft that may be connected with the tenth rotation element and that may be selectively connected with the second shaft. The first shaft and the eighth shaft each may be selectively connected with a transmission housing. 
         [0011]    The first, second, and third rotation elements of the first planetary gear set may be a first sun gear, a first planetary carrier, and a first ring gear, respectively, the fourth, fifth, and sixth rotation elements of the second planetary gear set may be a second sun gear, a second planetary carrier, and a second ring gear, respectively, the seventh, eighth, and ninth rotation elements of the third planetary gear set may be a third sun gear, a third planetary carrier, and a third ring gear, respectively, and the tenth, eleventh, and twelfth rotation elements of the fourth planetary gear set may be a fourth sun gear, a fourth planetary carrier, and a fourth ring gear, respectively. 
         [0012]    The planetary gear train may further include: a first clutch that may selectively connect the second shaft and the eighth shaft; a second clutch that may selectively connect the second shaft and the fifth shaft; a third clutch that may selectively connect the third shaft and the fifth shaft; a fourth clutch that may selectively connect the third shaft and the sixth shaft; a fifth clutch that may selectively connect the fourth shaft and the sixth shaft; a first brake that may selectively connect the first shaft and the transmission housing; and a second brake that may selectively connect the eighth shaft and the transmission housing. 
         [0013]    According to the present invention, by combining four planetary gear sets formed with a simplified planetary gear set with six control elements, a gear shift stage of at least forward fourteen-speed or more and a gear shift stage of at least reverse one-speed or more may be implemented. Further, according to the present invention, by forming a gear shift stage of an automatic transmission in a multistage, a gear shift stage appropriate to a rotation speed of an engine may be implemented, and particularly, running noise of a vehicle may be reduced by using a driving point in a low rotation speed range of the engine. 
         [0014]    Further, according to the present invention, engine driving efficiency may be maximized with a high efficiency multistage, and a power delivery performance and fuel consumption may be improved. In addition, an effect that may be obtained or estimated due to an exemplary embodiment of the present invention is directly or implicitly described in a detailed description of an exemplary embodiment of the present invention. That is, various effects that are estimated according to an exemplary embodiment of the present invention will be described within a detailed description to be described later. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]    The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description when taken in conjunction with the accompanying drawings, in which: 
           [0016]      FIG. 1  is a schematic diagram illustrating a planetary gear train according to an exemplary embodiment of the present invention; and 
           [0017]      FIG. 2  is a table illustrating operation based on each gear shift stage of a control element that is applied to a planetary gear train according to an exemplary embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0018]    It is understood that the term “vehicle” or “vehicular” or other similar term as used herein is inclusive of motor vehicles in general such as passenger automobiles including sports utility vehicles (SUV), buses, trucks, various commercial vehicles, watercraft including a variety of boats and ships, aircraft, and the like, and includes hybrid vehicles, electric vehicles, combustion, plug-in hybrid electric vehicles, hydrogen-powered vehicles and other alternative fuel vehicles (e.g. fuels derived from resources other than petroleum). 
         [0019]    The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. 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. 
         [0020]    Unless specifically stated or obvious from context, as used herein, the term “about” is understood as within a range of normal tolerance in the art, for example within  2  standard deviations of the mean. “About” can be understood as 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 clear from the context, all numerical values provided herein are modified by the term “about.” 
         [0021]    Hereinafter, an exemplary embodiment of the present invention will be described in detail with reference to the accompanying drawings. 
         [0022]      FIG. 1  is a schematic diagram illustrating a planetary gear train according to an exemplary embodiment of the present invention. Referring to  FIG. 1 , a planetary gear train according to an exemplary embodiment of the present invention may include first, second, third, and fourth planetary gear sets PG 1 , PG 2 , PG 3 , and PG 4  disposed on the same shaft line, an input shaft IS, an output shaft OS, eight shafts TM 1 -TM 8  that connect each rotation element of the first, second, third, and fourth planetary gear sets PG 1 , PG 2 , PG 3 , and PG 4 , five clutches C 1 -C 5  and two brakes B 1 -B 2 , which are control elements, and a transmission housing H. 
         [0023]    Rotation power from an engine input from the input shaft IS may be shifted by a mutual compensation operation of the first, second, third, and fourth planetary gear sets PG 1 , PG 2 , PG 3 , and PG 4  to be output through the output shaft OS. Particularly, the planetary gear sets may be disposed in order of the first, second, third, and fourth planetary gear sets PG 1 , PG 2 , PG 3 , and PG 4  from the engine side. The input shaft IS may be an input member, and a torque of rotation power from a crankshaft of the engine may be converted and input using a torque converter. The output shaft OS may be an output member and may be disposed on the same shaft line as that of the input shaft IS to deliver a shifted driving torque to a drive shaft using a differential apparatus. 
         [0024]    The first planetary gear set PG 1  may be a single pinion planetary gear set and may include a first sun gear S 1 , which is a first rotation element N 1 , a first planetary carrier PC 1 , which is a second rotation element N 2  configured to support a rotation of a first pinion gear P 1  externally engaged with the first sun gear S 1 , which is the first rotation element N 1 , and a first ring gear R 1 , which is a third rotation element N 3  internally engaged with the first pinion gear P 1 . The second planetary gear set PG 2  may be a single pinion planetary gear set and may include a second sun gear S 2 , which is a fourth rotation element N 4 , a second planetary carrier PC 2 , which is a fourth rotation element N 4  configured to support a rotation of a second pinion gear P 2  externally engaged with the second sun gear S 2 , which is the fourth rotation element N 4 , and a second ring gear R 2 , which is a sixth rotation element N 6  internally engaged with the second pinion gear P 2 . 
         [0025]    The third planetary gear set PG 3  may be a single pinion planetary gear set and may include a third sun gear S 3 , which is a seventh rotation element N 7 , a third planetary carrier PC 3 , which is an eighth rotation element N 8  configured to support a rotation of a third pinion gear P 3  externally engaged with the third sun gear S 3 , which is the seventh rotation element N 7 , and a third ring gear R 3 , which is a ninth rotation element N 9  internally engaged with the third pinion gear P 3 . The fourth planetary gear set PG 4  may be a single pinion planetary gear set and may include a fourth sun gear S 4 , which is a tenth rotation element N 10 , a fourth planetary carrier PC 4 , which is an eleventh rotation element N 11  configured to support a rotation of a fourth pinion gear P 4  externally engaged with the fourth sun gear S 4 , which is the tenth rotation element N 10 , and a fourth ring gear R 4 , which is a twelfth rotation element N 12  internally engaged with the fourth pinion gear P 4 . 
         [0026]    Particularly, in the first, second, third, and fourth planetary gear sets PG 1 , PG 2 , PG 3 , and PG 4 , the first rotation element N 1  may be directly connected with the fourth rotation element N 4 , the second rotation element N 2  may be directly connected with the sixth rotation element N 6 , the eighth rotation element N 8  may be directly connected with the twelfth rotation element N 12 , and the ninth rotation element N 9  may be directly connected with the eleventh rotation element N 11  and thus the first, second, third, and fourth planetary gear sets PG 1 , PG 2 , PG 3 , and PG 4  may operate while holding total eight shafts TM 1 -TM 8 . 
         [0027]    A configuration of the eight shafts TM 1 -TM 8  is described in detail as follows. The eight shafts TM 1 -TM 8  may be a rotation member configured to deliver power while rotating together with a rotation element connected to directly connect or to selectively connect a plurality of rotation elements among rotation elements of the planetary gear sets PG 1 , PG 2 , PG 3 , and PG 4  and may be a fixing member that directly connects and fixes the rotation element to the transmission housing H. 
         [0028]    The first shaft TM 1  may connect the first rotation element {N 1 ; first sun gear S 1 } and the fourth rotation element {N 10 ; fourth sun gear  54 } and may operate as a selective input element while being selectively connected with the transmission housing H. The second shaft TM 2  may include the second rotation element {N 2 ; first planetary carrier PC 1 } and the sixth rotation element {N 6 ; second ring gear}. The third shaft TM 3  may be connected with the third rotation element {N 3 ; first ring gear R 1 }. The fourth shaft TM 4  may be connected with the fifth rotation element {N 5 ; second planetary carrier PC 2 } and may be directly connected with the input shaft IS to operate as an input element. 
         [0029]    The fifth shaft TM 5  may be connected with the seventh rotation element {N 7 ; third sun gear S 3 } and may be selectively connected with the second shaft TM 2  and the third shaft TM 3 . The sixth shaft TM 6  may connect the eighth rotation element {N 8 ; third planetary carrier PC 3 } and the twelfth rotation element {N 12 ; fourth ring gear R 4 } and may be selectively connected with the fourth shaft TM 4  directly connected with the input shaft IS and the third shaft TM 3 . The seventh shaft TM 7  may connect the ninth rotation element {N 9 ; third ring gear R 3 } and the eleventh rotation element {N 11 ; fourth planetary carrier PC 4 } and may be directly connected with the output shaft OS to operate as an output element. The eighth shaft TM 8  may be connected with the tenth rotation element {N 10 ; fourth sun gear S 4 } and may be selectively connected with the second shaft TM 2  and the transmission housing H to operate as a selective input element. 
         [0030]    Among the eight shafts TM 1 -TM 8 , in a portion including the input shaft IS and the output shaft OS and that mutually selectively connects shafts, five clutches C 1 , C 2 , C 3 , C 4 , and C 5  may be disposed. Further, among the eight shafts TM 1 -TM 8 , in a portion in which the shaft and the transmission housing H are selectively connected, two brakes B 1  and B 2  may be disposed. A disposition location of the five clutches C 1 -C 5  and two brakes B 1 -B 2  is described as follows. 
         [0031]    The first clutch C 1  may be disposed between the second shaft TM 2  and the eighth shaft TM 8  to selectively connect the second shaft TM 2  and the eighth shaft TM 8  to deliver power. The second clutch C 2  may be disposed between the second shaft TM 2  and the fifth shaft TM 5  to selectively connect the second shaft TM 2  and the fifth shaft TM 5  to deliver power. The third clutch C 3  may be disposed between the third shaft TM 3  and the fifth shaft TM 5  to selectively connect the third shaft TM 3  and the fifth shaft TM 5  to deliver power. The fourth clutch C 4  may be disposed between the third shaft TM 3  and the sixth shaft TM 6  to selectively connect the third shaft TM 3  and the sixth shaft TM 6  to deliver power. The fifth clutch C 5  may be disposed between the fourth shaft TM 4  and the sixth shaft TM 6  to selectively connect the fourth shaft TM 4  directly connected with the input shaft IS and the sixth shaft TM 6  to deliver power. The first brake B 1  may be disposed between the first shaft TM 1  and the transmission housing H to selectively connect and fix the first shaft TM 1  to the transmission housing H. The second brake B 2  may be disposed between the eighth shaft TM 8  and the transmission housing H to selectively connect and fix the eighth shaft TM 8  to the transmission housing H. 
         [0032]    As shown in  FIG. 1 , in the foregoing description, it is described that the fifth clutch C 5  may selectively connect the fourth shaft TM 4  and the sixth shaft TM 6 . However, since the fourth shaft TM 4  may be directly connected with the input shaft IS, the fifth clutch C 5  may selectively connect the input shaft IS and the sixth shaft TM 6 . In the foregoing description, each control element formed with the first, second, third, fourth, and fifth clutches C 1 , C 2 , C 3 , C 4 , and C 5  and the first and second brakes B 1  and B 2  may be formed with a multi-plate type hydraulic pressure friction coupling unit friction coupled by a hydraulic pressure. 
         [0033]      FIG. 2  is a table illustrating operation based on each gear shift stage of a control element applied to a planetary gear train according to an exemplary embodiment of the present invention. Referring to  FIG. 2 , in each gear shift stage of the planetary gear train according to an exemplary embodiment of the present invention, among the first, second, third, fourth, and fifth clutches C 1 , C 2 , C 3 , C 4 , and C 5  and the first and second brakes B 1  and B 2 , which are control elements, while three elements operate, a shift of reverse two-speed and forward fourteen-speed may be performed, and a shift process is described as follows. 
         [0034]    In a forward one-speed gear shift stage Dl, the second and fourth clutches C 2  and C 4  and the second brake B 2  may be operated simultaneously with a gear ratio of about 8.067. Accordingly, when the second shaft TM 2  is connected with the fifth shaft TM 5  by operation of the second clutch C 2  and in which the third shaft TM 3  is connected with the sixth shaft TM 6  by operation of the fourth clutch C 4 , rotation power of the input shaft IS may be input to the fourth shaft TM 4 . The eighth shaft TM 8  may be shifted to a forward one-speed by a mutual compensation operation of each shaft while operating as a fixing element by operation of the second brake B 2  to output power through the output shaft OS connected with the seventh shaft TM 7 . 
         [0035]    In a forward second-speed gear shift stage D 2 , the second and third clutches C 2  and C 3  and the second brake B 2  may be operated simultaneously with a gear ratio of about 4.333. Additionally, the gear ratio between the D 1  and D 2  shift stages may be about 1.862. Accordingly, when the second shaft TM 2  is connected with the fifth shaft TM 5  by operation of the second clutch C 2  and in which the third shaft TM 3  is connected with the fifth shaft TM 5  by operation of the third clutch C 3 , rotation power of the input shaft IS may be input to the fourth shaft TM 4 . The eighth shaft TM 8  may be shifted to a forward two-speed by a mutual compensation operation of each shaft while operating as a fixing element by operation of the second brake B 2  to output power through the output shaft OS connected with the seventh shaft TM 7 . 
         [0036]    In a forward three-speed gear shift stage D 3 , the second clutch C 2  and the first and second brakes B 1  and B 2  may be operated simultaneously with a gear ratio of about 2.6. Additionally, the gear ratio between the D 2  and D 3  shift stages may be about 1.667. Accordingly, when the second shaft TM 2  is connected with the fifth shaft TM 5  by operation of the second clutch C 2 , rotation power of the input shaft IS may be input to the fourth shaft TM 4 . The first shaft TM 1  and the eighth shaft TM 8  may be shifted to a forward three-speed by a mutual compensation operation of each shaft while operating as a fixing element by operation of the first and second brakes B 1  and B 2  to output power through the output shaft OS connected with the seventh shaft TM 7 . 
         [0037]    In a forward four-speed gear shift stage D 4 , the third clutch C 3  and the first and second brakes B 1  and B 2  may be operated simultaneously with a gear ratio of about 2.022. Additionally the gear ratio between the D 3  and D 4  shift stages may be about 1.286. Accordingly, when the third shaft TM 3  is connected with the fifth shaft TM 5  by operation of the third clutch C 3 , rotation power of the input shaft IS may be input to the fourth shaft TM 4 . The first shaft TM 1  and the eighth shaft TM 8  may be shifted to a forward four-speed by a mutual compensation operation of each shaft while operating as a fixing element by operation of the first brake B 1  and the second brake B 2  to output power through the output shaft OS connected with the seventh shaft TM 7 . 
         [0038]    In a forward five-speed gear shift stage D 5 , the fifth clutch C 5  and the first and second brakes B 1  and B 2  may be operated simultaneously with a gear ratio of about 1.667. Additionally, the gear ratio between the D 4  and D 5  shift stages may be about 1.213. Accordingly, when the input shaft IS is connected with the sixth shaft TM 6  by operation of the fifth clutch C 5 , rotation power of the input shaft IS may be input to the fourth shaft TM 4  and the sixth shaft TM 6 . The first shaft TM 1  and the eighth shaft TM 8  may be shifted to a forward five-speed by a mutual compensation operation of each shaft while operating as a fixing element by operation of the first and second brake B 1  and B 2  to output power through the output shaft OS connected with the seventh shaft TM 7 . 
         [0039]    In a forward six-speed gear shift stage D 6 , the third and fifth clutches C 3  and C 5  and the first brake B 1  may be operated simultaneously with a gear ratio of about 1.4. Additionally, the gear ratio between the D 5  and D 6  shift stages may be about 1.19. Accordingly, when the third shaft TM 3  is connected with the fifth shaft TM 5  by operation of the third clutch C 3  and in which the input shaft IS may be connected with the sixth shaft TM 6  by operation of the fifth clutch C 5 , rotation power of the input shaft IS may be input to the fourth shaft TM 4  and the sixth shaft TM 6 . The first shaft TM 1  may be shifted to a forward six-speed by a mutual compensation operation of each shaft while operating as a fixing element by operation of the first brake B 1  to output power through the output shaft OS connected with the seventh shaft TM 7 . 
         [0040]    In a forward seven-speed gear shift stage D 7 , the second and fifth clutches C 2  and C 5  and the first brake B 1  may be operated simultaneously with a gear ratio of about 1.2. Additionally, the gear ratio between the D 6  and D 7  shift stages may be about 1.167. Accordingly, when the second shaft TM 2  is connected with the fifth shaft TM 5  by operation of the second clutch C 2  and in which the input shaft IS may be connected with the sixth shaft TM 6  by operation of the fifth clutch C 5 , rotation power of the input shaft IS may be input to the fourth shaft TM 4  and the sixth shaft TM 6 . The first shaft TM 1  may be shifted to a forward seven-speed by a mutual compensation operation of each shaft while operating as a fixing element by operation of the first brake B 1  to output power through the output shaft OS connected with the seventh shaft TM 7 . 
         [0041]    In a forward eight-speed gear shift stage D 8 , the first, second, and fifth clutches C 1 , C 2 , and C 5  may be operated simultaneously with a gear ratio of about 1. Additionally, the gear ratio between the D 7  and D 8  shift stages may be about 1.2. Accordingly, when the second shaft TM 2  is connected with the eighth shaft TM 8  by operation of the first clutch C 1  and in which the second shaft TM 2  is connected with the fifth shaft TM 5  by operation of the second clutch C 2  and in which the input shaft IS may be connected with the sixth shaft TM 6  by operation of the fifth clutch C 5 , rotation power of the input shaft IS may be input to the fourth shaft TM 4  and the sixth shaft TM 6 . Accordingly, while the entire planetary gear sets PG 1 , PG 2 , PG 3 , and PG 4  integrally rotate, the entire planetary gear sets PG 1 , PG 2 , PG 3 , and PG 4  may be shifted to a forward eight-speed that outputs the same value as an input value to output power through the output shaft OS connected with the seventh shaft TM 7 . 
         [0042]    In a forward nine-speed gear shift stage D 9 , the first and fifth clutches C 1  and C 5  and the first brake B 1  may be operated simultaneously with a gear ratio of about 0.789. Additionally, the gear ratio between the D 8  and D 9  shift stages may be about 1.267. Accordingly, when the second shaft TM 2  is connected with the eighth shaft TM 8  by operation of the first clutch C 1  and in which the input shaft IS may be connected with the sixth shaft TM 6  by operation of the fifth clutch C 5 , rotation power of the input shaft IS may be input to the fourth shaft TM 4  and the sixth shaft TM 6 . The first shaft TM 1  may be shifted to a forward nine-speed of an overdrive state by a mutual compensation operation of each shaft while operating as a fixing element by operation of the first brake B 1  to output power through the output shaft OS connected with the seventh shaft TM 7 . 
         [0043]    In a forward ten-speed gear shift stage D 10 , the first and second clutches C 1  and C 2  and the first brake B 1  may be operated simultaneously with a gear ratio of about 0.6. Additionally, the gear ratio between the D 9  and D 10  shift stages may be about 1.269. Accordingly, when the second shaft TM 2  is connected with the eighth shaft TM 8  by operation of the first clutch C 1  and in which the second shaft TM 2  is connected with the fifth shaft TM 5  by operation of the second clutch C 2 , rotation power of the input shaft IS may be input to the fourth shaft TM 4 . The first shaft TM 1  may be shifted to a forward ten-speed of an overdrive state by a mutual compensation operation of each shaft while operating as a fixing element by operation of the first brake B 1  to output power through the output shaft OS connected with the seventh shaft TM 7 . 
         [0044]    In a forward eleven-speed gear shift stage D 11 , the first and third clutches C 1  and C 3  and the first brake B 1  may be operated simultaneously with a gear ratio of about 0.563. Additionally, the gear ratio between the D 10  and D 11  shift stages may be about 1.066. Accordingly, when the second shaft TM 2  is connected with the eighth shaft TM 8  by operation of the first clutch C 1  and in which the third shaft TM 3  is connected with the fifth shaft TM 5  by operation of the third clutch C 3 , rotation power of the input shaft IS may be input to the fourth shaft TM 4 . The first shaft TM 1  may be shifted to a forward eleven-speed of an overdrive state by a mutual compensation operation of each shaft while operating as a fixing element by operation of the first brake B 1  to output power through the output shaft OS connected with the seventh shaft TM 7 . 
         [0045]    In a forward twelve-speed gear shift stage D 12 , the first and fourth clutches C 1  and C 4  and the first brake B 1  may be operated simultaneously with a gear ratio of about 0.512. Additionally, the gear ratio between the D 11  and D 12  shift stages may be about 1.099. Accordingly, when the second shaft TM 2  is connected with the eighth shaft TM 8  by operation of the first clutch C 1  and in which the third shaft TM 3  is connected with the sixth shaft TM 6  by operation of the fourth clutch C 4 , rotation power of the input shaft IS may be input to the fourth shaft TM 4 . The first shaft TM 1  may be shifted to a forward twelve-speed of an overdrive state by a mutual compensation operation of each shaft while operating as a fixing element by operation of the first brake B 1  to output power through the output shaft OS connected with the seventh shaft TM 7 . 
         [0046]    In a forward thirteen-speed gear shift stage D 13 , the third and fourth clutches C 3  and C 4  and the first brake B 1  may be operated simultaneously with a gear ratio of about 0.467. Additionally, the gear ratio between the D 12  and D 13  shift stages may be about 1.098. Accordingly, when the third shaft TM 3  is connected with the fifth shaft TM 5  by operation of the third clutch C 3  and in which the third shaft TM 3  is connected with the sixth shaft TM 6  by operation of the fourth clutch C 4 , rotation power of the input shaft IS may be input to the fourth shaft TM 4 . The first shaft TM 1  may be shifted to a forward thirteen-speed of an overdrive state by a mutual compensation operation of each shaft while operating as a fixing element by operation of the first brake B 1  to output power through the output shaft OS connected with the seventh shaft TM 7 . 
         [0047]    In a forward fourteen-speed gear shift stage D 14 , the second and fourth clutches C 2  and C 4  and the first brake B 1  may be operated simultaneously operated with a gear ratio of about 0.442. Additionally, the gear ratio between the D 13  and D 14  shift stages may be about 1.056. Accordingly, when the second shaft TM 2  is connected with the fifth shaft TM 5  by operation of the second clutch C 2  and in which the third shaft TM 3  is connected with the sixth shaft TM 6  by operation of the fourth clutch C 4 , rotation power of the input shaft IS may be input to the fourth shaft TM 4 . The first shaft TM 1  may be shifted to a forward fourteen-speed, which may be a shift stage of a highest speed by a mutual compensation operation of each shaft while operating as a fixing element by operation of the first brake B 1  to output power through the output shaft OS connected with the seventh shaft TM 7 . 
         [0048]    In a reverse one-speed gear shift stage REV 1 , the first and third clutches C 1  and C 3  and the second brake B 2  may be operated simultaneously with a gear ratio of about −6.067. Accordingly, when the second shaft TM 2  is connected with the eighth shaft TM 8  by operation of the first clutch C 1  and in which the third shaft TM 3  is connected with the fifth shaft TM 5  by operation of the third clutch C 3 , rotation power of the input shaft IS may be input to the fourth shaft TM 4 . The eighth shaft TM 8  may be shifted to a reverse one-speed by a mutual compensation operation of each shaft while operating as a fixing element by operation of the second brake B 2  to output power through the output shaft OS connected with the seventh shaft TM 7 . 
         [0049]    In a reverser two-speed gear shift stage REV 2 , the first and fourth clutches C 1  and C 4  and the second brake B 2  may be operated simultaneously with a gear ratio of about −2.333. Accordingly, when the second shaft TM 2  is connected with the eighth shaft TM 8  by operation of the first clutch C 1  and in which the third shaft TM 3  is connected with the sixth shaft TM 6  by operation of the fourth clutch C 4 , rotation power of the input shaft IS may be input to the fourth shaft TM 4 . The eighth shaft TM 8  may be shifted to a reverse two-speed by a mutual compensation operation of each shaft while operating as a fixing element by operation of the second brake B 2  to output power through the output shaft OS connected with the seventh shaft TM 7 . 
         [0050]    As described above, a planetary gear train according to an exemplary embodiment of the present invention may enable four planetary gear sets PG 1 , PG 2 , PG 3 , and PG 4  to realize a gear shift stage of at least forward fourteen-speed or more and at least reverse two-speed or more through an operation control of five clutches C 1 , C 2 , C 3 , C 4 , and C 5  and two brakes B 1  and B 2 . Further, by forming a gear shift stage of an automatic transmission in a multistage, a planetary gear train according to an exemplary embodiment of the present invention may implement a gear shift stage appropriate to a rotation speed of an engine and particularly, may reduce running noise of a vehicle by using a driving point in a low rotation speed range of the engine. 
         [0051]    Further, by forming an automatic transmission in a multistage, a planetary gear train according to an exemplary embodiment of the present invention may maximize engine driving efficiency and improve a power delivery performance and fuel consumption. Additionally, a planetary gear train according to an exemplary embodiment of the present invention may implement a reverse two-speed of gear shift stage to improve a reverse performance 
         [0052]    While this invention has been described in connection with what is presently considered to be exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.