Patent Application
20170159759
The present application claims priority to and the benefit of Korean Patent Application No. 10-2015-0171005 filed on Dec. 2, 2015, the entire contents of which is incorporated herein for all purposes by this reference.
Field of the Invention
The present invention relates to an automatic transmission for a vehicle.
Description of Related Art
Recent increases in oil prices are triggering hard competition in enhancing fuel consumption of a vehicle.
In this sense, research on an engine has been undertaken to achieve weight reduction and to enhance fuel consumption by so-called downsizing, and research on an automatic transmission has been performed to simultaneously provide better drivability and fuel consumption by achieving more shift stages.
In order to achieve more shift stages for an automatic transmission, the number of parts is typically increased, which may deteriorate installability, production cost, weight, and/or power flow efficiency.
Therefore, in order to maximally enhance fuel consumption of an automatic transmission having more shift stages, it is important for better efficiency to be derived by a smaller number of parts.
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 having advantages of, by minimal complexity, realizing at least eight forward speeds and at least one reverse speed, thereby improving power delivery performance and fuel consumption due to multi-stages, and improving driving stability of a vehicle by utilizing a low rotation speed of an engine.
An exemplary planetary gear set according to an embodiment includes an input shaft for receiving an engine torque, an output shaft for outputting a shifted torque, a first planetary gear set having first, second, and third rotational elements, a second planetary gear set having fourth, fifth, and sixth rotational elements, a third planetary gear set having seventh, eighth, and ninth rotational elements, and six control elements for selectively interconnecting the rotational elements and a transmission housing.
The exemplary planetary gear set may further include a first connecting member connected with the first rotational element and the ninth rotational element, a second connecting member connected with the second rotational element and the fourth rotational element and directly connected with the input shaft, a third connecting member connected with the third rotational element, a fourth connecting member connected with the fifth rotational element and selectively connectable with the first connecting member and the third connecting member, a fifth connecting member connected with the sixth rotational element, a sixth connecting member connected with the seventh rotational element, selectively connectable with the fifth connecting member, and selectively connectable with the transmission housing, and a seventh connecting member connected with the eighth rotational element, selectively connectable with the fifth connecting member, and directly connected with the output shaft.
The first planetary gear set may be a single pinion planetary gear set, where the first rotational element is a first sun gear, the second rotational element is a first planet carrier, and the third rotational element is a first ring gear. The second planetary gear set may be a single pinion planetary gear set, where the fourth rotational element is a second sun gear, the fifth rotational element is a second planet carrier, and the sixth rotational element is a second ring gear. The third planetary gear set may be a single pinion planetary gear set, where the seventh rotational element is a third sun gear, the eighth rotational element is a third planet carrier, and the ninth rotational element is a third ring gear.
The six control elements may include a first clutch selectively connecting the fifth connecting member and the seventh connecting member, a second clutch selectively connecting the first connecting member and the fourth connecting member, a third clutch selectively connecting the third connecting member and the fourth connecting member, a fourth clutch selectively connecting the fifth connecting member and the sixth connecting member, a first brake selectively connecting the fourth connecting member and the transmission housing, and a second brake selectively connecting the sixth connecting member and the transmission housing.
Shift stages realized by the operation of the six control elements may include a forward first speed formed by simultaneous operation of the second and fourth clutches and the second brake, a forward second speed formed by simultaneous operation of the first and second clutches and the second brake, a forward third speed formed by simultaneous operation of the second and third clutches and the second brake, a forward fourth speed formed by simultaneous operation of the first and third clutches and the second brake, a forward fifth speed formed by simultaneous operation of the first, third, and fourth clutches, a forward sixth speed formed by simultaneous operation of the third and fourth clutches and the second brake, a forward seventh speed formed by simultaneous operation of the third and fourth clutches and the first brake, a forward eighth speed formed by simultaneous operation of the third clutch and the first and second brakes, and a reverse speed formed by simultaneous operation of the first and fourth clutches and the first brake.
A planetary gear train according to an exemplary embodiment of the present invention may realize at least eight forward speeds and at least one reverse speed formed by operating the three planetary gear sets as simple planetary gear sets by controlling six control elements.
In addition, a planetary gear train according to an exemplary embodiment of the present invention may substantially improve driving stability by realizing shift stages appropriate for rotation speed of an engine due to multi-stages of an automatic transmission.
In addition, a planetary gear train according to an exemplary embodiment of the present invention may maximize engine driving efficiency by multi-stages of an automatic transmission, and may improve power delivery performance and fuel consumption.
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.
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.
The drawings and description are to be regarded as illustrative in nature and not restrictive, and like reference numerals designate like 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,
Referring to
Torque input from the input shaft IS is shifted by cooperative operation of the first, second, and third planetary gear sets PG1, PG2, and PG3, and then output through the output shaft OS.
The simple planetary gear sets are arranged in the order of first, second, and third planetary gear sets PG1, PG2, and PG3, from an engine side.
The input shaft IS is an input member and the torque from a crankshaft of an engine, after being torque-converted through a torque converter, is input into the input shaft IS.
The output shaft OS is an output member, and being arranged on a same axis with the input shaft IS, delivers a shifted torque to a drive shaft through a differential apparatus.
The first planetary gear set PG1 is a single pinion planetary gear set, and includes a first sun gear S1, a first planet carrier PC1 that supports a first pinion P1 externally engaged with the first sun gear S1, and a first ring gear R1 internally engaged with the first pinion P1. The first sun gear S1 ads as a first rotational element N1, the first planet carrier PC1 acts as a second rotational element N2, and the first ring gear R1 acts as a third rotational element N3.
The second planetary gear set PG2 is a single pinion planetary gear set, and includes a second sun gear S2, a second planet carrier PC2 that supports a second pinion P2 externally engaged with the second sun gear S2, and a second ring gear R2 internally engaged with the second pinion P2. The second sun gear S2 acts as a fourth rotational element N4, the second planet carrier PC2 acts as a fifth rotational element N5, and the second ring gear R2 acts as a sixth rotational element N6.
The third planetary gear set PG3 is a single pinion planetary gear set, and includes a third sun gear S3, a third planet carrier PC3 that supports a third pinion P3 externally engaged with the third sun gear S3, and a third ring gear R3 internally engaged with the third pinion P3. The third sun gear S3 acts as a seventh rotational element N7, the third planet carrier PC3 acts as an eighth rotational element N8, and the third ring gear R3 acts as a ninth rotational element N9.
In the arrangement of the first, second, and third planetary gear sets PG1, PG2, and PG3, the first rotational element N1 is directly connected with the ninth rotational element N9, and the second rotational element N2 is directly connected with the fourth rotational element N4, by seven connecting members TM1 to TM7.
The seven connecting members TM1 to TM7 are arranged as follows.
The first connecting member TM1 is connected with the first rotational element N1 (first sun gear S1) and the ninth rotational element N9 (third ring gear R3).
The second connecting member TM2 is connected with the second rotational element N2 (first planet carrier PC1) and the fourth rotational element N4 (second sun gear S2), and is directly connected with the input shaft IS.
The third connecting member TM3 is connected with third rotational element N3 (first ring gear R1).
The fourth connecting member TM4 is connected with the fifth rotational element N5 (second planet carrier S2), selectively connectable with the first connecting member TIM and the third connecting member TM3, and selectively connectable with the transmission housing H.
The fifth connecting member TM5 is connected with sixth rotational element N6 (second ring gear R2).
The sixth connecting member TM6 is connected with the seventh rotational element N7 (third sun gear S3), selectively connectable with the fifth connecting member TM5, and selectively connectable with the transmission housing H.
The seventh connecting member TM7 is connected with the eighth rotational element N8 (third planet carrier PC3), selectively connectable with the fifth connecting member TM5, and directly connected with the output shaft OS.
The connecting members TM1 to TM7 may be selectively interconnected with one another by control elements of four clutches C1, C2, C3, and C4.
The connecting members TM1 to TM8 may be selectively connectable with the transmission housing H, by control elements of two brakes B1 and B2.
The six control element C1 to C4 and B1 to B2 are arranged as follows.
The first clutch C1 is arranged between the fifth connecting member TM5 and the seventh connecting member TM7, such that the fifth connecting member TM5 and the seventh connecting member TM7 may selectively become integral.
The second clutch C2 is arranged between the first connecting member TM1 and the fourth connecting member TM4, such that the first connecting member TM1 and the fourth connecting member TM4 may selectively become integral.
The third clutch C3 is arranged between the third connecting member TM3 and the fourth connecting member TM4, such that the third connecting member TM3 and the fourth connecting member TM4 may selectively become integral.
The fourth clutch C4 is arranged between the fifth connecting member TM5 and the sixth connecting member TM6, such that the fifth connecting member TM5 and the sixth connecting member TM6 may selectively become integral.
The first brake B1 is arranged between the fourth connecting member TM4 and the transmission housing H, such that the fourth connecting member TM4 may selectively act as a fixed element.
The second brake B2 is arranged between the sixth connecting member TM6 and the transmission housing H, such that the sixth connecting member TM6 may selectively act as a fixed element.
The control elements of the first, second, third, and fourth clutches C1, C2, C3, and C4 and the first and second brakes B1 and B2 may he realized as multi-plate hydraulic pressure friction devices that are frictionally engaged by hydraulic pressure.
As shown in
In the forward first speed D1, the second and fourth clutches C2 and C4 and the second brake B2 are simultaneously operated. As a result, the first connecting member TM1 and the fourth connecting member TM4 are interconnected by the operation of the second clutch C2, and the fifth connecting member TM5 and the sixth connecting member TM6 are interconnected by the operation of the fourth clutch C4. In this state, torque is input to the second connecting member TM2. In addition, the sixth connecting member TM6 simultaneously acts as a fixed element by the operation of second brake B2, thereby realizing the forward first speed and outputting a shifted torque through the output shaft OS connected with seventh connecting member TM7.
In the forward second speed D2, the first and second clutches C1 and C2 and the second brake B2 are simultaneously operated. As a result, the fifth connecting member TM5 and the seventh connecting member TM7 are interconnected by the operation of the first clutch C1, and the first connecting member TM1 and the fourth connecting member TM4 are interconnected by the operation of the second clutch C2. In this state, torque is input to the second connecting member TM2. In addition, the sixth connecting member TM6 simultaneously acts as a fixed element by the operation of second brake B2, thereby realizing the forward second speed and outputting a shifted torque through the output shaft OS connected with seventh connecting member TM7.
In the forward third speed D3, the second and third clutches C2 and C3 and the second brake B2 are simultaneously operated. As a result, the first connecting member TM1 and the fourth connecting member TM4 are interconnected by the operation of the second clutch C2, and the third connecting member TM3 and the fourth connecting member TM4 are interconnected by the operation of the third clutch C3. In this state, torque is input to the second connecting member TM2. In addition, the sixth connecting member TM6 simultaneously acts as a fixed element by the operation of second brake B2, thereby realizing the forward third speed and outputting a shifted torque through the output shaft OS connected with seventh connecting member TM7.
In the forward fourth speed D4, the first and third clutches C1 and C3 and the second brake B2 are simultaneously operated. As a result, the fifth connecting member TM5 and the seventh connecting member TM7 are interconnected by the operation of the first clutch C1, and the third connecting member TM3 and the fourth connecting member TM4 are interconnected by the operation of the third clutch C3. In this state, torque is input to the second connecting member TM2. In addition, the sixth connecting member TM6 simultaneously acts as a fixed element by the operation of second brake B2, thereby realizing the forward fourth speed and outputting a shifted torque through the output shaft OS connected with seventh connecting member TM7.
In the forward fifth speed D5, the first, third, and fourth clutches C1, C3, and C4 are simultaneously operated. As a result, the fifth connecting member TM5 and the seventh connecting member TM7 are interconnected by the operation of the first clutch C1, the third connecting member TM3 and the fourth connecting member TM4 are interconnected by the operation of the third clutch C3, and the fifth connecting member TM5 and the sixth connecting member TM6 are interconnected by the operation of the fourth clutch C4. In this state, torque is input to the second connecting member TM2. The, the first, second, and third planetary gear sets PG1, PG2, and PG3 rotates integral, and the forward fifth speed outputting a torque as inputted is realized, outputting the torque through the output shaft connected with the seventh connecting member TM7.
In the forward sixth speed D6, the third and fourth clutches C3 and C4 and the second brake B2 are simultaneously operated. As a result, the third connecting member TM3 and the fourth connecting member TM4 are interconnected by the operation of the third clutch C3, and the fifth connecting member TM5 and the sixth connecting member TM6 are interconnected by the operation of the fourth clutch C4. In this state, torque is input to the second connecting member TM2. In addition, the sixth connecting member TM6 simultaneously acts as a fixed element by the operation of second brake B2, thereby realizing the forward sixth speed and outputting a shifted torque through the output shaft OS connected with seventh connecting member TM7.
In the forward seventh speed D7, the third and fourth clutches C3 and C4 and the first brake B1 are simultaneously operated. As a result, the third connecting member TM3 and the fourth connecting member TM4 are interconnected by the operation of the third clutch C3, and the fifth connecting member TM5 and the sixth connecting member TM6 are interconnected by the operation of the fourth clutch C4. In this state, torque is input to the second connecting member TM2. In addition, the fourth connecting member TM4 simultaneously acts as a fixed element by the operation of first brake B1, thereby realizing the forward seventh speed and outputting a shifted torque through the output shaft OS connected with seventh connecting member TM7.
In the forward eighth speed D8, the third clutch C3 and the first and second brakes B1 and B2 are simultaneously operated. As a result, the third connecting member TM3 and the fourth connecting member TM4 are interconnected by the operation of the third clutch C3, and torque is input to the second connecting member TM2. In addition, the fourth and the sixth connecting members TM4 and TM6 simultaneously act as fixed elements by the operation of the first and second brakes B1 and B2, thereby realizing the forward eighth speed and outputting a shifted torque through the output shaft OS connected with seventh connecting member TM7.
In the reverse speed REV, the second and fourth clutches C2 and C4 and the first brake B1 are simultaneously operated. As a result, the first connecting member TM1 and the fourth connecting member TM4 are interconnected by the operation of the second clutch C2, and the fifth connecting member TM5 and the sixth connecting member TM6 are interconnected by the operation of the fourth clutch C4. In this state, torque is input to the second connecting member TM2. In addition, the fourth connecting member TM4 simultaneously acts as a fixed element by the operation of first brake B1, thereby realizing the reverse speed and outputting a shifted torque through the output shaft OS connected with the seventh connecting member TM7.
As described above, a planetary gear train according to an exemplary embodiment of the present invention may realize at least eight forward speeds and at least one reverse speed formed by operating the three planetary gear sets PG1, PG2, and PG3 by controlling the four clutches C1, C2, C3, and C4 and the two brakes B1 and B2.
In addition, a planetary gear train according to an exemplary embodiment of the present invention may substantially improve driving stability by realizing shift stages appropriate for rotation speed of an engine due to multi-stages of an automatic transmission.
In addition, a planetary gear train according to an exemplary embodiment of the present invention may maximize engine driving efficiency by multi-stages of an automatic transmission, and may improve power delivery performance and fuel consumption.
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.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2015-0171005 | Dec 2015 | KR | national |
