KR100793893B1 - 8 - shift gear train in an automatic transmission for vehicles - Google Patents

Abstract

An 8-shift gear train in an automatic transmission for vehicles is provided to improve a power delivery efficiency by decreasing the number of planetary gears operating at forward sixth to eighth speeds. A first transmission(T1) includes first and second input paths and a first planetary gear set. A second transmission(T2) includes fourth rotation components. Some of operation components in second and third planetary gear sets are inter-coupled with one another. Three of the rotation components in the second transmission are variably connected to an intermediate output path through first to third intermediate input paths. The rest rotation component operates as an output component. Two of the three rotation components operate as selective fixing components. Plural clutches(C1-C4) variably couple some of the rotation components in the first and second transmissions with each other. Plural brakes(B1-B3) variably couple some of the rotation components in the first and second transmissions with a transmission housing.

Description

8-SHIFT GEAR TRAIN IN AN AUTOMATIC TRANSMISSION FOR VEHICLES}

1 shows a gear train of an automatic transmission according to the invention;

Figure 2 is an operating table of the friction element applied to the gear train according to the present invention.

3 is a speed diagram of a gear train according to the present invention.

The present invention relates to a gear train of an 8 speed automatic transmission for a vehicle.

In general, a multi-stage shifting mechanism of an automatic transmission is implemented by combining a plurality of planetary gearsets, and a gear train in which the plurality of planetary gearsets is combined receives a rotational power from a torque converter and shifts it to the output shaft. Will be

In such a sucrose transmission, the more gears that can be implemented, the more appropriate the gear ratio can be designed and the vehicle can be realized in terms of power performance and fuel efficiency. .

And even if the same shift stage is implemented, the durability, power transmission efficiency, size, etc. of the gear train vary according to the combination method of the planetary gear set, and thus, to invent a more robust, lossless, and more compact power train configuration Efforts are always going on.

In particular, unlike a manual transmission in which a shifting speed is more inconvenient for a driver, the automatic transmission shifts by controlling a gear train in accordance with a driving state. Efforts are being made to find a gear train configuration that can be implemented.

From this point of view, four-speed and five-speed automatic transmissions are the mainstream automatic transmissions currently in use, but recently six-speed automatic transmissions have been developed and applied to vehicles. Development is currently in progress.

Accordingly, the present inventors have proposed the present invention to meet the development of the automatic transmission as described above, and an object of the present invention is to convert one simple planetary gear set and one compound planetary gear set into a plurality of clutches and brakes. By combining the eight forward speed and the second reverse speed, it is possible to provide a gear train for an eight-speed automatic transmission for improving the power transmission performance and reducing fuel consumption.

In order to achieve the above object, the present invention provides a first input path through which rotational power is directly input from an input shaft, a second input path through which rotational power is selectively input from the input shaft, and an input only by the first input path. A first transmission portion comprising a first planetary gear set having an intermediate output path at which a deceleration output is made and at the same time an input is made to the first and second input paths and an output at the same speed as the input;

Some of the operating elements of the second and third planetary gearsets are interconnected to hold four rotating elements while three of the rotating elements are variably connected to the intermediate output path through the first, second and third intermediate input paths, A second transmission portion in which the remaining one rotating element is operated as an output element, and wherein two of the variable three rotating elements are configured to act as selective fixing elements;

A plurality of clutches for variably connecting some of the rotating elements of the rotating elements of the first and second transmission parts;

Provided is a gear train of an 8-speed automatic transmission for a vehicle including a plurality of brakes that variably connect a rotational element of a part of the rotational elements of the first and second transmission units to a transmission housing.

Hereinafter, with reference to the accompanying drawings, preferred embodiments of the present invention will be described in more detail.

 1 is a block diagram of a gear train according to the present invention, which includes a first transmission portion T1 formed of a single pinion type first planetary gear set PG1 and a single pinion type second and third planetary gear set PG2 ( By including the second transmission portion (T2) made of a combination of PG3, the rotation input from the input shaft (IS) is shifted while passing through the first, second transmission (T1) (T2) output gear (OG) Will be printed).

The input shaft IS refers to the turbine shaft of the torque converter as an input member, which means that the rotational power from the crank shaft of the engine is input while torque conversion is performed through the torque converter, and the output gear OG is known as the output member. The left and right drive wheels are driven by the differential.

The first planetary gear set PG1 constituting the first shifting unit T1 is selectively input through two input paths, and a deceleration or output is performed at the same speed as the input through one intermediate output path. You lose.

That is, the first rotating element N1 of the three rotary elements of the first planetary gear set PG1 constituting the first transmission part T1 is always directly connected to the input shaft IS to always be an input element. The second rotating element N2 is variably connected to the input shaft IS to operate as an optional input element, and at the same time the rotational power shifted from the first planetary gear set PG1 is always at the second transmission part T2. The third rotary element N3 is variably connected to the transmission housing H to operate as an optional fixing element.

In order to achieve the above operation, in the present invention, the first input is always performed by directly connecting the sun gear S1 which is the first rotating element N1 of the first planetary gear set PG1 with the input shaft IS. The route IP1 was formed.

In addition, the planetary carrier PC1, which is the second rotary element N2 supporting the first pinion P1, is variably connected via the input shaft IS and the first clutch C1, and the second transmission portion ( The second input path IP2 and the intermediate output path OP were formed by connecting with some of the operating elements of the second and third planetary gear sets PG2 and PG3 forming T2).

In addition, the ring gear R1, which is the third rotating element N3, is variably connected to the transmission housing H and the first brake B1, so that it can operate as an optional fixing element.

Accordingly, when the first brake B1 is operated in a state in which the first clutch C1 is released, a deceleration output is performed through the second rotating element N2 (the planet carrier PC1) as the output member. When the first clutch C1 is operated, simultaneous input is performed through the first and second input paths IP1 and IP2, so that the first planetary gear set PG1 is directly connected to the second rotating element which is an output sub-item. {N2, planet carrier PC1} is to output the same speed with the same rotational speed as the input.

The second and third planetary gear sets PG2 and PG3 constituting the second transmission portion T2 are partially connected to each other to form four rotating elements N4 to N7.

More specifically, the fourth rotating element N4 is a sun gear S3 of the third planetary gear set PG3, and the fifth rotating element N5 is a ring gear R2 of the second planetary gear set PG2. The planetary carrier PC3 of the third planetary gear set PG3 and the sixth rotating element N6 are ring gears of the planetary carrier PC2 and the third planetary gearset PG3 of the second planetary gearset PG2. R3), the seventh rotating element N7 is composed of the sun gear S2 of the third planetary gear set PG2.

To this end, the planetary carrier PC2 supporting the pinion P2 of the second planetary gear set PG2 and the ring gear R3 of the third planetary gear set PG3 are directly connected to each other and the second planetary gear set is simultaneously connected. The ring gear R2 of PG2 and the planetary carrier PC3 supporting the pinion P3 of the third planetary gear set PG3 are directly connected.

The fifth rotary element N5 (the planetary carrier PC2, the ring gear R3) and the fourth rotary element N4 (the sun gear S3) are respectively the second brake B2 and the third brake B3. It is connected to the transmission housing (H) via the to act as an optional fixing element.

In addition, the fourth rotary element N4 and the sun gear S3 are selectively connected to the intermediate output path OP through the first intermediate input path CP1 formed of the third clutch C3, and the fifth rotary element N4. (N5; planet carrier (C3), ring gear (R2)} is selectively connected to the intermediate output path (OP) via a second intermediate input path (CP2) consisting of a fourth clutch (C4), The rotary element N6 (the planet carrier PC2, the ring gear R3) is connected to the output gear OG, which is an output member, and the seventh rotary element NN; the sun gear S2 is connected to the third clutch C3. The intermediate output path OP is selectively connected to the third intermediate input path CP3.

In the above description, the first, second, third and fourth clutches C1 to C4 and the first, second and third brakes B1 to B3 generally include a multi-plate hydraulic friction coupling unit in which the clutch and the brake are frictionally coupled by hydraulic pressure. to be.

2 is an operation table showing that the friction elements applied to the present invention, that is, the clutch and the brake operate at each shift stage, in which [●] indicates operation, [○] indicates operation or non-operation, "Operation off" is indicated, and the gear train of the present invention can be seen that the shift is made while the three friction elements in each shift stage is operating.

FIG. 3 shows a shift diagram of the gear train according to the present invention, in which the horizontal line on the lower side represents the rotational speed "0" and the horizontal line on the lower side represents the rotational speed "1.0", that is, the same rotational speed as the input shaft IS. .

Each vertical line of the first transmission portion T1 may be a sun gear S1 that is a first rotation element N1, a planetary carrier PC1 that is a second rotation element N2, and a third rotation element N3. It is set to ring gear R1, and these intervals are determined according to the gear ratio (number of teeth of sun gear / number of rings of teeth) of the first planetary gear set PG1.

In addition, the four vertical lines of the second transmission portion T2 are sun gear S3 of the third planetary gear set PG3, which is the fourth rotary element N4, and a second planetary gear, which is the fifth rotary element N5, from the left side. Ring gear R2 of set PG2 and planetary carrier PC3 of third planetary gear set PG3, planetary carrier PC2 and second planetary gear set PG2 of sixth rotating element N6 (3) Ring gear (R3) of planetary gear set (PG3), and planetary gear (S2) of second planetary gear set (PG2), which is the seventh rotating element (N7). It is determined according to the gear ratio of (PG2) (PG3), and the above-described transmission diagram is well known to those skilled in the art of the gear train, and thus detailed description thereof will be omitted.

[1st speed forward]

In the forward 1 speed, as shown in FIG. 2, the third clutch C3 and the first and second brakes B1 and B2 are operated and controlled.

Then, in the first transmission part T1, the third rotation element N3 is operated as a fixed element by the operation of the first brake B1 while the input is made to the first rotation element N1. The deceleration output is made via element N2.

In the second transmission portion T2, the output of the second rotating element N2 is input to the seventh rotating element N7 by the operation of the third clutch C3. As the fifth rotating element N5 is operated as a fixed element, the output is made through the sixth rotating element N6, thereby forming the first transmission line SP1, and the first transmission line SP1. As the output of D1 connecting the sixth rotating element N6, which is an output element, is made, the shift of the first forward speed is made.

[2 speed forward]

At the second forward speed, the operation of the second brake B2 among the friction elements operated at the first forward speed is released, and the third brake B3 is operated and controlled.

Then, as in the first forward speed, the third rotation element N3 is operated as the fixed element by the operation of the first brake B1 while the first transmission element T1 is input to the first rotation element N1. The bar is made to be decelerated through the second rotating element N2.

In the second transmission part T2, the output of the second rotating element N2 is input to the seventh rotating element N7 by the operation of the third clutch C3. As the fourth rotary element N4 is operated as a fixed element, the output is made through the sixth rotary element N6, thereby forming a second transmission line SP2, and a second transmission line SP2 thereof. As the output of D2 connecting the sixth rotating element N6, which is an output element, is made, the second shift speed is made.

[3rd forward first draft]

At the third forward speed, the operation of the third brake B3 among the friction elements operated at the second forward speed is released, and the second clutch C2 is controlled to operate.

Then, as in the second forward speed, the third rotation element N3 is operated as a fixed element by the operation of the first brake B1 in the state where an input is made to the first rotation element N1 in the first transmission portion T1. The bar is made to be decelerated through the second rotating element N2.

In the second transmission part T2, the output of the second rotating element N2 is transferred to the fourth rotating element N4 and the seventh rotating element N7 by the operation of the second and third clutches C2 and C3. As it is input, the third transmission line SP3 is formed by outputting the output of the second rotation element N2 through the sixth rotation element N6 while being in a direct connection state, and thus the third transmission line ( As the output of D3 connecting SP3) and the sixth rotating element N6, which is an output element, is made, the third forward speed is made.

[3 speed 2nd draft]

In addition, unlike the first eye, the first brake B1 and the second and fourth clutches C2 and C4 may be operated to control the third forward speed.

That is, in the first transmission portion T1, the third rotation element N3 is operated as a fixed element by the operation of the first brake B1 in the state where an input is made to the first rotation element N1 as in the first proposal. The deceleration output is made through the second rotating element N2.

In the second transmission part T2, the output of the second rotating element N2 is transferred to the fourth rotating element N4 and the fifth rotating element N5 by the operation of the second and fourth clutches C2 and C4. As it is input, the third transmission line SP3 is formed by outputting the output of the second rotation element N2 through the sixth rotation element N6 while being in a direct connection state, and thus the third transmission line ( As the output of D3 connecting SP3) and the sixth rotating element N6, which is an output element, is made, the third forward speed is made.

[3rd speed third proposal]

In addition, unlike the first and second eyes, the third brake may be implemented by operating the first brake B1 and the third and fourth clutches C3 and C4.

That is, in the first transmission portion T1, the third rotation element N3 is operated as a fixed element by the operation of the first brake B1 while the input is made to the first rotation element N1 as in the first and second eyes. The bar is made to be decelerated through the second rotating element N2.

In the second transmission portion T2, the output of the second rotating element N2 is transferred to the third rotating element N3 and the seventh rotating element N7 by the operation of the third and fourth clutches C3 and C4. As it is input, the third transmission line SP3 is formed by outputting the output of the second rotation element N2 through the sixth rotation element N6 while being in a direct connection state, and thus the third transmission line ( As the output of D3 connecting SP3) and the sixth rotating element N6, which is an output element, is made, the third forward speed is made.

[4 forward speed]

At 4th forward speed, the first and third clutches C1 and C3 and the second brake B2 are operated and controlled.

Then, in the first transmission part T1, the input is also made to the second rotating element N2 by the operation of the first clutch C1 while the input is made to the first rotating element N1. The output will be output as is.

In addition, in the second transmission part T2, the second brake B2 is operated when the output of the second rotary element N2 is input to the seventh rotary element N7 by the operation of the third clutch C3. As the fifth rotating element N5 operates as the fixed element, the output is made through the sixth rotating element N6, thereby forming a fourth transmission line SP4, and the fourth transmission line SP4 and the output thereof. As the output of D4 connecting the sixth rotating element N6, which is an element, is made, shifting of the fourth forward speed is made.

[5th forward]

At the 5th forward speed, the operation of the second brake B2 among the friction elements operated at the 4th forward speed is released, and the third brake B3 is operated and controlled.

Then, in the first transmission part T1, the input is also made to the second rotating element N2 by the operation of the first clutch C1 while the input is made to the first rotating element N1. The output will be output as is.

In addition, in the second transmission portion T2, the third brake C3 is operated when the output of the second rotary element N2 is input to the seventh rotary element N7 by the operation of the third clutch C3. As the fourth rotary element N4 operates as a fixed element, the output is made through the sixth rotary element N6, thereby forming a fifth shift line SP5, and the fifth shift line SP5 and the output thereof. As the output of D5 connecting the sixth rotating element N6, which is an element, is made, shifting of five forward speeds is achieved.

[6th forward]

At the sixth forward speed, the first and third clutches C1 and C3 of the friction elements operated at the fifth forward speed are released, and the fourth clutch C4 and the first brake B1 are operated and controlled.

Then, in the first transmission part T1, the third rotation element N3 is operated as a fixed element by the operation of the first brake B1 while the input is made to the first rotation element N1. The deceleration output is made via element N2.

In addition, in the second transmission portion T2, when the output of the second rotating element N2 is input to the fifth rotating element N5 by the operation of the fourth clutch C4, the third brake B3 operates. As the fourth rotary element N4 operates as a fixed element, the output is made through the sixth rotary element N6, thereby forming a sixth shift line SP6, and outputting the sixth shift line SP6. As the output of D6 connecting the sixth rotating element N6, which is an element, is made, shifting of six forward speeds is achieved.

[7th forward first draft]

At seventh forward speed, the first, second and third clutches C1, C2 and C3 are operated and controlled.

Then, in the first transmission part T1, the input is also made to the second rotating element N2 by the operation of the first clutch C1 while the input is made to the first rotating element N1. The output will be output as is.

In the second transmission part T2, the output of the second rotating element N2 is transferred to the fourth rotating element N4 and the seventh rotating element N7 by the operation of the second and third clutches C2 and C3. As it is input, the seventh speed shift line SP7 is formed while being in a direct connection state, and the output of the second rotating element N2 is transferred as much as D7 through the sixth rotating element N6 to move forward. The seventh shift is to be made.

[7th forward second draft]

In addition, unlike the first scheme, the first and second clutches C1 and C2 and the fourth clutch C4 may be controlled by operation.

That is, in the first transmission portion T1, the input is also made to the second rotating element N2 by the operation of the first clutch C1 in the state where the input is made to the first rotating element N1 as in the first proposal. The bar is directly connected and the output is output as it is.

In the second transmission part T2, the output of the second rotating element N2 is transferred to the fourth rotating element N4 and the fifth rotating element N5 by the operation of the second and fourth clutches C2 and C4. As it is input, the seventh speed shift line SP7 is formed while being in a direct connection state, and the output of the second rotating element N2 is transferred as much as D7 through the sixth rotating element N6 to move forward. Seven speed shifts will be achieved.

[3rd speed third proposal]

In addition, unlike the first and second eyes, the first, third, and fourth clutches C1, C3, and C4 may be operated and controlled.

That is, in the first transmission part T1, the input is made to the second rotating element N2 by the operation of the first clutch C1 in the state where the input is made to the first rotating element N1 as in the first and second eyes. As it turns out, it is directly connected and outputs the input as it is.

In addition, in the second transmission part T2, the third brake B3 is operated when the output of the second rotating element N2 is input to the fifth rotating element N5 by the operation of the fourth clutch C4. As a result of the output being made through the sixth rotating element N6 while the fourth rotating element N4 operates as a fixed element, an eighth transmission line SP8 is formed, and the eighth transmission line SP8 As the output of D8 connecting the sixth rotating element N6, which is an output element, is made, shifting of eight forward speeds is achieved.

[1 speed reverse]

In the reverse 1 speed, the second clutch C2 and the first and second brakes B1 and B2 are operated and controlled.

Then, in the first transmission part T1, the third rotation element N3 is operated as a fixed element by the operation of the first brake B1 while the input is made to the first rotation element N1. The deceleration output is made via element N2.

In addition, in the second transmission part T2, the second brake B2 is operated when the output of the second rotating element N2 is input to the fourth rotating element N4 by the operation of the second clutch C2. As the fifth rotary element N5 operates as a fixed element, the output is made through the sixth rotary element N6, thereby forming a reverse first shift line RS1, and a reverse first shift line thereof. Reverse rotation output is made as much as SR1 connecting RS1 and the sixth rotation element N6 that is the output element, and shifting of the reverse first speed is made.

[2 speed reverse]

In the reverse 1 speed, the operation of the first brake B1 is released in the state of the reverse 1 speed, and the first clutch C1 is operated and controlled.

Then, in the first transmission part T1, the input is also made to the second rotating element N2 by the operation of the first clutch C1 while the input is made to the first rotating element N1 as in the first and second eyes. As soon as it is in direct connection, the output is output as it is.

In addition, in the second transmission part T2, the second brake B2 is operated when the output of the second rotating element N2 is input to the fourth rotating element N4 by the operation of the second clutch C2. By the operation of the fifth rotating element (N5) is a fixed element while the output is made through the sixth rotating element (N6), thereby forming a reverse second transmission line (RS2), the reverse second transmission line The reverse rotational output is made as much as SR2 connecting RS2 and the sixth rotation element N6, which is an output element, so that the second shift speed is made.

In addition to the sequential shift as described above, the present invention provides 8 → 6, 8 → 5, 7 → 5, 7 → 4, 7 → 3, 6 → 3, 6 → 2, 5 → 2, 4 → 1, 3 → 1 It is possible to shift down, and in the case of up skipping, it can be reversed from the above, by changing only the friction element operation of any one of the three operating friction elements.

Although a preferred embodiment of the gear train of the present invention has been described above, the present invention is not limited to the above embodiment, and those skilled in the art can easily invent the present invention from the embodiment of the present invention. It includes all modifications to the extent deemed to be equivalent.

As described above, according to the present invention, one simple planetary gear set and one compound planetary gear set may be combined with four clutches and three brakes to implement 8 forward speeds and 2 reverse speeds. Since the number of the transmission planetary gears at speeds 7,7 and 8 is small as shown in FIG. 2, the transmission efficiency of the power transmission can be improved.

In addition, the seventh forward is an underdrive, and the overdrive operation is performed only at the eighth forward speed, and thus the rotation speed inside the transmission is relatively small, thereby improving durability.

Claims (8)

The first input path through which the rotational power is directly input from the input shaft, the second input path through which the rotational power is selectively input from the input shaft, and the deceleration output is performed when the input is performed only by the first input path. A first transmission unit comprising a first planetary gear set having an intermediate output path at which input and output are performed at the same time when two input paths are simultaneously inputted; Some of the operating elements of the second and third planetary gearsets are interconnected to hold four rotating elements while three of the rotating elements are variably connected to the intermediate output path through the first, second and third intermediate input paths, A second transmission portion in which the remaining one rotating element is operated as an output element, and wherein two of the variable three rotating elements are configured to act as selective fixing elements; A plurality of clutches for variably connecting some of the rotating elements of the rotating elements of the first and second transmission parts; And a plurality of brakes for variably connecting the rotating elements of some of the rotating elements of the first and second transmission units to the transmission housing. The planetary gear set of claim 1, wherein the first planetary gear set forming the first shifting unit is a single pinion planetary gear set, comprising: a first rotating element made of a sun gear; A second rotating element comprising a planetary carrier; Retaining a third rotating element consisting of a ring gear, The first rotating element is directly connected to the input shaft through a first input path, the second rotating element is variably connected to the input shaft through a second input path and is formed as an intermediate output path, and the third rotating element is a transmission housing. Gear train of an 8-speed automatic transmission for vehicles. The method of claim 1, wherein the second transmission portion has four rotating elements in combination of the second and third planetary gear sets, which are single pinion planetary gear sets. A fourth rotating element comprising a sun gear of the third planetary gear set; A fifth rotating element comprising a ring gear of the second planetary gear set and a planet carrier of the third planetary gear set; A sixth rotating element comprising a planetary carrier of the second planetary gearset and a ring gear of the third planetary gearset; A gear train of an eight-speed automatic transmission for a vehicle, characterized in that it comprises a seventh rotational element consisting of a sun gear of a third planetary gear set. 4. The fourth rotating element of claim 3, wherein the fourth rotating element is selectively connected to the intermediate output path through the first intermediate input path and variably connected to the transmission housing, and the fifth rotating element is the intermediate output through the second intermediate input path. It is selectively connected to the path and variably connected to the transmission housing, wherein the sixth rotating element is connected to the output gear which is an output member, and the seventh rotating element is selectively connected to the intermediate output path through the third intermediate input path. A gear train of an 8-speed automatic transmission for a vehicle, characterized in that.  A single pinion planetary gear set, comprising: a first rotating element made of a sun gear; A second rotating element comprising a planetary carrier; A first planetary gear set having a third rotating element made of a ring gear, wherein the first rotating element is directly connected to an input shaft through a first input path, and the second rotating element is input shaft through a second input path. And a third transmission element which is variably connected to the intermediate output path and which is variably connected to the transmission housing; A fourth rotating element made of the sun gear of the third planetary gear set by a combination of the second and third planetary gear sets which are single pinion planetary gear sets; A fifth rotating element comprising a ring gear of the second planetary gear set and a planet carrier of the third planetary gear set; A sixth rotating element comprising a planetary carrier of the second planetary gearset and a ring gear of the third planetary gearset; A seventh rotating element comprising a sun gear of the third planetary gear set, wherein the fourth rotating element is selectively connected to the intermediate output path through the first intermediate input path and variably connected to the transmission housing; The element is selectively connected to the intermediate output path via a second intermediate input path and variably connected to the transmission housing, the sixth rotating element is connected to an output gear which is an output member, and the seventh rotating element is a third intermediate A second transmission part selectively connected to the intermediate output path through an input path; A plurality of clutches for variably connecting some of the rotating elements of the rotating elements of the first and second transmission parts; And a plurality of brakes for variably connecting a rotational element of a part of the rotational elements of the first and second transmission units to the transmission housing. The clutch of claim 5 wherein the clutch is A first clutch forming a second input path; A second clutch forming a first intermediate input path; A third clutch forming a third intermediate input path; A gear train of an eight-speed automatic transmission for a vehicle, characterized in that it comprises a fourth clutch forming a second intermediate input path. The brake of claim 5, wherein the brake is A first brake connecting the first rotating element to the transmission housing; A second brake connecting the fifth rotating element to the transmission housing; And a third brake for connecting the fourth operating element to the transmission housing.  A single pinion planetary gear set, comprising: a first rotating element made of a sun gear; A second rotating element comprising a planetary carrier; A first planetary gear set having a third rotating element made of a ring gear, wherein the first rotating element is directly connected to an input shaft through a first input path, and the second rotating element is input shaft through a second input path. And a third transmission element which is variably connected to and is formed as an intermediate output path, and wherein the third rotating element is variably connected to the transmission housing; A fourth rotating element made of the sun gear of the third planetary gear set by a combination of the second and third planetary gear sets which are single pinion planetary gear sets; A fifth rotating element comprising a ring gear of the second planetary gear set and a planet carrier of the third planetary gear set; A sixth rotating element comprising a planetary carrier of the second planetary gearset and a ring gear of the third planetary gearset; A seventh rotating element comprising a sun gear of the third planetary gear set, wherein the fourth rotating element is selectively connected to the intermediate output path through the first intermediate input path and variably connected to the transmission housing; The element is selectively connected to the intermediate output path via a second intermediate input path and variably connected to the transmission housing, the sixth rotating element is connected to an output gear which is an output member, and the seventh rotating element is a third intermediate A second transmission part selectively connected to the intermediate output path through an input path; A first clutch forming the second input path, a second clutch forming the first intermediate input path, a third clutch forming the third intermediate input path, and forming the second intermediate input path A plurality of clutches comprising a fourth clutch; A plurality of brakes comprising a first brake connecting the first rotating element to the transmission housing, a second brake connecting all the elements to the transmission housing, and a third brake connecting the fourth operating element to the transmission housing. Gear train of 8-speed automatic transmission for vehicles including brakes.

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