Planetary gear train of automatic transmission for vehicles

The present application claims priority to and the benefit of Korean Patent Application No. 10-2015-0129868 filed on Sep. 14, 2015, the entire contents of which is incorporated herein for all purposes by this reference.

The present invention relates to an automatic transmission for a vehicle. More particularly, the present invention relates to that improves power delivery performance and fuel consumption and obtains a linearity between step ratios of transmission steps by enlarging a span of gear ratios while achieving nine forward speed stages using a minimum number of constituent elements.

The recent increase in oil prices causes carmakers to meet global demands of improving fuel efficiency.

Accordingly, researches are being conducted on engines in terms of reducing weight and improving fuel efficiency by down-sizing, and researches are also being conducted to ensure both drivability and competitiveness by maximizing fuel efficiency by implementing an automatic transmission with multiple stages.

However, in the case of the automatic transmission, the number of internal components is increased as the number of gear shift stages is increased, which may cause deterioration in terms of mountability, costs, weight and power transmission efficiency.

Therefore, in order to increase an effect of improving fuel efficiency by implementing an automatic transmission with multiple stages, it is important to develop a planetary gear train capable of maximizing efficiency using a small number of components.

In this respect, recently, an eight-speed automatic transmission has been implemented, and researches and developments are being actively conducted on a planetary gear train that may implement gear shift stages for eight or more speeds.

However, in the case of the recent eight-speed automatic transmission, a span of a gear shift ratio is maintained at a level of 6.5 to 7.5, and as a result, there is a problem in that the recent eight-speed automatic transmission has no great effect of improving fuel efficiency.

In a case in which a span of a gear shift ratio in the eight-speed automatic transmission is increased to the level of 9.0 or more, because it is impossible to ensure linearity of step ratios between gear shift stages, driving efficiency of the engine and drivability of the vehicle deteriorate.

Accordingly, there is a need for development of a highly efficient automatic transmission with 9 or more forward speed stages.

The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.

Various aspects of the present invention are directed to providing a planetary gear train of an automatic transmission for a vehicle that improves power delivery performance and fuel efficiency and ensures linearity of step ratios between transmission steps by increasing a span of gear ratios while realizing at least nine forward speed stages and at least one reverse speed stage by using a minimum number of constituent elements.

A planetary gear train of an automatic transmission for vehicles according to the present invention includes an input shaft receiving power of an engine; an output shaft outputting shifted 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; and six control elements disposed at a portion selectively connecting the rotation elements and the rotation elements or a portion selectively connecting the rotation elements and the transmission housing, wherein the input shaft is continuously connected to the third rotation element, the output shaft is continuously connected to the eleventh rotation element, the second rotation element is continuously connected to the eleventh rotation element, the third rotation element is continuously connected to the fourth rotation element, the sixth rotation element is continuously connected to the eighth rotation element, the ninth rotation element is continuously connected to the tenth rotation element, the fifth rotation element is selectively connected to the transmission housing, while three control elements of the seven control elements are operated, at least nine forward speed stages and at least one reverse speed stage are implemented.

The seventh rotation element may be selectively connected to the transmission housing, the twelfth rotation element may be selectively connected to the transmission housing, the input shaft may be selectively connected to the fifth rotation element, the fifth rotation element may be selectively connected to the ninth rotation element, and the first rotation element may be selectively connected to the twelfth rotation element.

The first, second, and third rotation elements of the first planetary gear set may be a sun gear, a planet carrier, and a ring gear, respectively, the fourth, fifth, and sixth rotation elements of the second planetary gear set may be a sun gear, a planet carrier, and a ring gear, respectively, the seventh, eighth, and ninth rotation elements of the third planetary gear set may be a sun gear, a planet carrier, and a ring gear, and the tenth, eleventh, and twelfth rotation elements of the fourth planetary gear set may be a sun gear, a planet carrier, and a ring gear.

The planetary gear train according to an exemplary embodiment of the present invention may implement the gear shift stages for nine forward speed stages and one reverse speed stage by combining four planetary gear sets with the six control elements.

In addition, a span of a gear shift ratio is 9.0 or more, thereby maximizing driving efficiency of the engine.

In addition, the linearity of the interstage ratio of the shift stage is secured while multi-staging the shift stage at high efficiency, thereby making it possible to improve drivability such as acceleration before and after the shift, an engine speed rhythmic sense, and the like.

Further, effects that can be obtained or expected from exemplary embodiments of the present invention are directly or suggestively described in the following detailed description. That is, various effects expected from exemplary embodiments of the present invention will be described in the following detailed description.

The methods and apparatuses of the present invention have other features and advantages which will be apparent from or are set forth in more detail in the accompanying drawings, which are incorporated herein, and the following Detailed Description, which together serve to explain certain principles of the present invention.

FIG. 1 is a configuration diagram of a planetary gear train according to a first exemplary embodiment of the present invention.

FIG. 2 is an operation table for each of transmission steps of respective control elements applied to the planetary gear train according to the first exemplary embodiment of the present invention.

It should be understood that the appended drawings are not necessarily to scale, presenting a somewhat simplified representation of various features illustrative of the basic principles of the invention. The specific design features of the present invention as disclosed herein, including, for example, specific dimensions, orientations, locations, and shapes will be determined in part by the particular intended application and use environment.

In the figures, reference numbers refer to the same or equivalent parts of the present invention throughout the several figures of the drawing.

Reference will now be made in detail to various embodiments of the present invention(s), examples of which are illustrated in the accompanying drawings and described below. While the invention(s) will be described in conjunction with exemplary embodiments, it will be understood that the present description is not intended to limit the invention(s) to those exemplary embodiments. On the contrary, the invention(s) is/are intended to cover not only the exemplary embodiments, but also various alternatives, modifications, equivalents and other embodiments, which may be included within the spirit and scope of the invention as defined by the appended claims.

The present invention will be described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments of the invention are shown. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention.

However, parts which are not related with the description are omitted for clearly describing the exemplary embodiment of the present invention, and like reference numerals refer to like or similar elements throughout the specification.

In the following description, dividing names of components into first, second, and the like is to divide the names because the names of the components are the same as each other, and an order thereof is not particularly limited.

FIG. 1 is a configuration diagram of a planetary gear train according to a first exemplary embodiment of the present invention.

Referring to FIG. 1 , the planetary gear train according to an exemplary embodiment of the present invention includes first, second, third, fourth planetary gear sets PG 1 , PG 2 , PG 3 , and PG 4 disposed on the same axis, an input shaft IS, an output shaft OS, eight rotation shafts TM 1 to TM 8 directly connecting to each other through respective rotation elements of the first, second, third, and fourth planetary gear sets PG 1 , PG 2 , PG 3 , and PG 4 , six control elements C 1 -C 3 and B 1 -B 3 , and a transmission housing H.

As a result, torque input from the input shaft IS is transmitted by an inter-complementation 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.

The respective simple planetary gear sets are disposed in a sequence of the first, second, third, and fourth planetary gear sets PG 1 , PG 2 , PG 3 , and PG 4 from an engine side.

The input shaft IS is an input member, and rotational power from a crankshaft of an engine is torque-converted through a torque converter to be input into the input shaft IS.

The output shaft OS is an output member, is disposed on the same axis as the input shaft IS, and transfers transmitted driving torque to a driving shaft through a differential apparatus.

The first planetary gear set PG 1 is a single pinion planetary gear set, and includes rotation elements including a first sun gear S 1 which is a first rotation element N 1 , a first planet carrier PC 1 which is a second rotation element N 2 for supporting a first pinion P 1 that externally engages with the first sun gear S 1 that is the first rotation element N 1 , and a first ring gear R 1 which is a third rotation element N 3 that internally engages with the first pinion P 1 .

The second planetary gear set PG 2 is a single pinion planetary gear set, and includes a second sun gear S 2 which is a fourth rotation element N 4 , a second planet carrier PC 2 which is a fifth rotation element N 5 for supporting a second pinion P 2 that externally engages with the second sun gear S 2 that is the fourth rotation element N 4 , and a second ring gear R 2 which is a sixth rotation element N 6 that internally engages with the second pinion P 2 .

The third planetary gear set PG 3 is a single pinion planetary gear set, and includes a third sun gear S 3 which is a seventh rotation element N 7 , a third planet carrier PC 3 which is an eighth rotation element N 8 for supporting a third pinion P 3 that externally engages with the third sun gear S 3 that is the seventh rotation element N 7 , and a third ring gear R 3 which is a ninth rotation element N 9 that internally engages with the third pinion P 3 .

The fourth planetary gear set PG 4 is a single pinion planetary gear set and includes a fourth sun gear S 4 which is a tenth rotation element N 10 , a fourth planet carrier PC 4 which is an eleventh rotation element N 11 for supporting a fourth pinion P 4 that externally engages with the fourth sun gear S 4 that is the tenth rotation element N 10 , and a fourth ring gear R 4 which is a twelfth rotation element N 12 that internally engages with the fourth pinion P 4 .

The first, second, third, and fourth planetary gear sets PG 1 , PG 2 , PG 3 , and PG 4 are operated while retaining the total of eight rotating shafts TM 1 to TM 8 in a state in which the second rotation elements N 2 is directly connected to the eleventh rotation elements N 11 , the third rotation elements N 3 is directly connected to the fourth rotation elements N 4 , the sixth rotation elements N 6 is directly connected to the eighth rotation elements N 8 , and the ninth rotation elements N 9 is directly connected to the tenth rotation elements N 10 .

Also, the first, second, third, fourth planetary gear sets PG 1 , PG 2 , PG 3 , and PG 4 are all disposed on the output shaft OS by the connection configurations.

The configurations of the eight rotating shafts TM 1 to TM 8 will be described below.

The first rotation shaft TM 1 includes a first rotation element N 1 (a first sun gear S 1 ).

The second rotation shaft TM 2 includes a second rotation element N 2 (a first planetary carrier PC 1 ) and an eleventh rotation element N 11 (a fourth planetary carrier PC 4 ) and is directly connected to the output shaft OS so as to continuously be operated as an output element.

The the third rotation shaft TM 3 includes a third rotation element N 3 (a first ring gear R 1 ) and a fourth rotation element N 4 (a second sun gear S 2 ) and is directly connected to the input shaft IS so as to continuously be operated as an input element.

The fourth rotation shaft TM 4 includes a fifth rotation element N 5 (a second planetary carrier PC 2 ) and is selectively connected to the third rotation shaft TM 3 and simultaneously is selectively connected to the transmission housing H.

The fifth rotation shaft TM 5 includes a sixth rotation elements N 6 (a second ring gear R 2 ) and an eighth rotation element N 8 (a third planetary carrier PC 3 ).

The sixth rotation shaft TM 6 includes a seventh rotation elements N 7 (a third sun gear S 3 ) and is selectively connected to the transmission housing H.

The seventh rotation shaft TM 7 includes a ninth rotation element N 9 (a third ring gear R 3 ) and is selectively connected to the fourth rotation shaft TM 4 .

The eighth rotation shaft TM 8 includes a twelfth rotation element N 12 (a fourth ring gear R 4 ) and is selectively connected to the first rotation shaft TM 1 and simultaneously is selectively connected to the transmission housing H.

Further, three clutches C 1 , C 2 , and C 3 , which are control elements, are disposed at portions where the rotating shafts of the rotating shafts TM 1 to TM 8 are selectively connected to each other.

In addition, three brakes B 1 , B 2 , and B 3 , which are control elements, are disposed at portions where the rotating shafts of the rotating shafts TM 1 to TM 8 are selectively connected with the transmission housing H.

The arrangement positions of the six control elements C 1 -C 3 and B 1 -B 3 will be described below.

The first clutch C 1 is disposed between the third rotation shaft TM 3 and the fourth rotation shaft TM 4 to allow the third rotation shaft TM 3 to the fourth rotation shaft TM 4 to be selectively integrated with each other.

The second clutch C 2 is disposed between the fourth rotation shaft TM 4 and the seventh rotation shaft TM 7 to allow the fourth rotation shaft TM 4 and the seventh rotation shaft TM 7 to be selectively integrated with each other.

The third clutch C 3 is disposed between the first rotation shaft TM 1 and the eighth rotation shaft TM 8 to allow the first rotation shaft TM 1 and the eighth rotation shaft TM 8 to be selectively integrated with each other.

The first brake B 1 is interposed between the fourth rotational shaft TM 4 and the transmission housing H to allow the fourth rotational shaft TM 4 to be operated as a selective fixing element.

The second brake B 2 is interposed between the sixth rotational shaft TM 6 and the transmission housing H to allow the sixth rotational shaft TM 6 to be operated as the selective fixing element.

The third brake B 3 is interposed between the eighth rotational shaft TM 8 and the transmission housing H to allow the eighth rotational shaft TM 8 to be operated as the selective fixing element.

The respective control elements including the first, second, and third clutches C 1 , C 2 , and C 3 , and the first, second, and third brakes B 1 , B 2 , and B 3 may be formed of a multi-plate type hydraulic friction coupling unit which is frictionally coupled by hydraulic pressure.

FIG. 2 is an operation table for each of transmission steps of respective control elements applied to the planetary gear train according to the first exemplary embodiment of the present invention.

As shown in FIG. 2 , the planetary gear train according to the exemplary embodiment of the present invention is shifted while three control elements are operated in each shift stage.

The second clutch C 2 and the second and third brakes B 2 and B 3 are simultaneously operated at the first forward speed stage D 1 . Therefore, in a stage in which the fourth rotation shaft TM 4 is connected to the seventh rotation shaft TM 7 to each other by the operation of the second clutch C 2 , the power is inputted to the third rotation shaft TM 3 , while the sixth rotation shaft TM 6 and the eighth rotation shaft TM 8 are operated as a fixing element by the operation of the second, third brakes B 2 and B 3 , the shift is realized into the first forward speed and the power is output through the output shaft OS including the second rotation shaft TM 2 .

The first and second clutches C 1 and C 2 and the third brake B 3 are simultaneously operated in the second forward speed stage D 2 . Therefore, in a stage in which the third rotation shaft TM 3 is connected to the fourth rotation shaft TM 4 to each other by the operation of the first clutch C 1 and the fourth rotation shaft TM 4 is connected to the seventh rotation shaft TM 7 to each other by the operation of the second clutch C 2 , the power is inputted to the third rotation shaft TM 3 , while the eighth rotation shaft TM 8 is operated as a fixing element by operation of the third brake B 3 , the shift is realized into the second forward speed and the power is output through the output shaft OS including the second rotation shaft TM 2 .

The first clutch C 1 and the second and third brakes B 2 and B 3 are simultaneously operated in the third forward speed stage D 3 . Therefore, in a state in which the third rotation shaft TM 3 is connected to the fourth rotation shaft TM 4 by the operation of the first clutch C 1 , the power is inputted to the third rotation shaft TM 3 , while the sixth rotation shaft TM 6 and the eighth rotation shaft TM 8 are operated as a fixing element by the operation of the second and third brakes B 2 and B 3 , the shift is realized into the three forward speed and the power is output through the output shaft OS including the second rotation shaft TM 2 .

The first and third clutches C 1 and C 3 and the third brake B 3 are simultaneously operated in the fourth forward speed stage D 4 . Therefore, in a stage in which the third rotation shaft TM 3 is connected to the fourth rotation shaft TM 4 to each other by the operation of the first clutch C 1 and the first rotation shaft TM 1 is connected to the eighth rotation shaft TM 8 to each other by the operation of the third clutch C 3 , the power is inputted to the third rotation shaft TM 3 , while the eighth rotation shaft TM 8 is operated as a fixing element by the operation of the third brake B 3 , the shift is realized into the fourth forward speed and the power is output through the output shaft OS including the second rotation shaft TM 2 .

The first and third clutches C 1 and C 3 and the second brake B 2 are simultaneously operated at the fifth forward speed stage D 5 . Therefore, in a stage in which the third rotation shaft TM 3 is connected to the fourth rotation shaft TM 4 to each other by the operation of the first clutch C 1 and the first rotation shaft TM 1 is connected to the eighth rotation shaft TM 8 to each other by the operation of the third clutch C 3 , the power is inputted to the third rotation shaft TM 3 , while the sixth rotation shaft TM 6 is operated as a fixing element by the operation of the second brake B 2 , the shift is realized into a fifth forward speed and the power is output through the output shaft OS including the second rotation shaft TM 2 .

The first, second, and third clutches C 1 , C 2 , and C 3 are simultaneously operated at a sixth forward speed stage D 6 . Therefore, the third rotation shaft TM 3 is connected to the fourth rotation shaft TM 4 to each other by the operation of the first clutch C 1 and the fourth rotation shaft TM 4 is connected to the seventh rotation shaft TM 7 to each other by the operation of the second clutch C 2 , and the first rotation shaft TM 1 is connected to the eighth rotation shaft TM 8 to each other by the operation of the third clutch C 3 , thereby forming a stage in which the first, second, third, and fourth planetary gear sets PG 1 , PG 2 , PG 3 , and PG 4 are all directly connected, the input into the third rotation shaft TM 3 is output through the output shaft OS including the second rotation shaft TM 2 as it is.

The second and third clutches C 2 and C 3 and the second brake B 2 are simultaneously operated at a seventh forward speed stage D 7 . Therefore, in a state in which the fourth rotation shaft TM 4 is connected to the seventh rotation shaft TM 7 to each other by the operation of the second clutch C 2 and the first rotation shaft TM 1 is connected to the eighth rotation shaft TM 8 to each other by the operation of the third clutch C 3 , the power is inputted to the third rotation shaft TM 3 , while the sixth rotation shaft TM 6 is operated as a fixing element by the operation of the second brake B 2 , the shift is realized into the seventh forward speed and the power is output through the output shaft OS including the second rotation shaft TM 2 .

The second and third clutches C 2 and C 3 and the first brake B 1 are simultaneously operated at an eighth forward speed stage D 8 . Therefore, in a stage in which the fourth rotation shaft TM 4 is connected to the seventh rotation shaft TM 7 to each other by the operation of the second clutch C 2 and the first rotation shaft TM 1 is connected to the eighth rotation shaft TM 8 to each other by the operation of the third clutch C 3 , the power is inputted to the third rotation shaft TM 3 , while the fourth rotation shaft TM 4 is operated as a fixing element by the operation of the first brake B 1 , the shift is realized into the eighth forward speed and the power is output through the output shaft OS including the second rotation shaft TM 2 .

The third clutch C 3 and the first and second brakes B 1 and B 2 are simultaneously operated at a ninth forward speed stage D 9 . Therefore, in a stage in which the first rotation shaft TM 1 is connected to the eighth rotation shaft TM 8 to each other by the operation of the third clutch C 3 , the power is inputted to the third rotation shaft TM 3 , while the fourth rotation shaft TM 4 and the sixth rotation shaft TM 6 are operated as a fixing element by the operation of the first and second brakes B 1 and B 2 , the shift is realized into the ninth forward speed stage and the power is output through the output shaft OS including the second rotation shaft TM 2 .

The first, second, and third brakes B 1 , B 2 , and B 3 are simultaneously operated at a reverse speed stage REV. Therefore, the power is inputted to the third rotation shaft TM 3 , while the fourth rotation shaft TM 4 , the sixth rotation shaft TM 6 , and the eighth rotation shaft TM 8 are operated as a fixing element by the operation of the first, second, and third brakes B 1 , B 2 , and B 3 , the shift is realized into the reverse speed and the power is output through the output shaft OS including the second rotation shaft TM 2 .

The planetary gear train according to the exemplary embodiment of the present invention may implement the gear shift stages for nine forward speed stages and one reverse speed stage by operating and controlling the four planetary gear sets PG 1 , PG 2 , PG 3 , and PG 4 using the three clutches C 1 , C 2 , and C 3 and the three brakes B 1 , B 2 , and B 3 .

In addition, the linearity of the interstage ratio of the shift stage is secured while multi-staging the shift stage at high efficiency, thereby making it possible to improve drivability such as acceleration before and after the shift, an engine speed rhythmic sense, and the like.

In addition, a span of a gear shift ratio is 9.0 or more, thereby maximizing driving efficiency of the engine.

For convenience in explanation and accurate definition in the appended claims, the terms “upper”, “lower”, “inner” and “outer” are used to describe features of the exemplary embodiments with reference to the positions of such features as displayed in the figures.

The foregoing descriptions of specific exemplary embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teachings. The exemplary embodiments were chosen and described in order to explain certain principles of the invention and their practical application, to thereby enable others skilled in the art to make and utilize various exemplary embodiments of the present invention, as well as various alternatives and modifications thereof. It is intended that the scope of the invention be defined by the Claims appended hereto and their equivalents.