JP2006342910A - Six-speed power train for vehicular automatic transmission - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power train for an automatic transmission having compact construction with reduced total length and weight while actualizing shift stages consisting of six forward speeds and one reverse speed by combining three planetary gear sets and five friction elements. <P>SOLUTION: The power train for the automatic transmission comprises a combination of one single pinion planetary gear set and two double pinion planetary gear sets. Two simple planetary gear sets out of three simple planetary gear sets have two operating elements fixed and connected to each other and combined with composite planetary gear sets holding four operating elements to hold seven operating elements in total. Namely, it holds a combination of one normally input element and two selectively input elements, one normally fixed element and two selectively fixed elements, and one intermediately output element and one normally output element. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a 6-speed power train of an automatic transmission for a vehicle that can be applied to an automatic transmission for a vehicle and realize a 6-speed shift stage.

For example, a multi-speed gear mechanism of an automatic transmission is composed of a combination of a plurality of planetary gear sets, and a power train combining such a plurality of planetary gear sets converts torque and transmits engine torque. If rotational power is input from the converter, it has a function of shifting it in multiple stages and transmitting it to the output side.
Since the power train of such an automatic transmission is more advantageous in terms of power performance and fuel consumption as the number of shift stages is increased, a power train capable of realizing more shift stages is required.

Even if the same number of gears is achieved, the durability and power transmission efficiency, size, weight, etc. vary greatly depending on the method of combining planetary gear sets, making it more robust and compact while minimizing power loss. Efforts to develop powertrains continue.
In developing a powertrain that uses planetary gear sets, instead of developing a new planetary gear set, how to combine existing single pinion planetary gear sets and double pinion planetary gear sets, Consider where and how much clutches and brakes and one-way clutches should be arranged, and reduce the power loss as much as possible to achieve the desired gear and the gear ratio according to it to improve the transmission performance. Various researches are being promoted with the goal of

In particular, in the case of a manual transmission, if there are too many shift stages, there is an inconvenience that the driver has to shift frequently, but in the case of an automatic transmission, the transmission control unit automatically changes depending on the driving state. In addition, since shifting is performed by controlling the operation of the power train, it can be said that it is very valuable to develop a power train that can realize more shift stages.
In response to these trends, various studies on 4-speed and 5-speed powertrains have been advanced, and recently, an automatic transmission powertrain capable of realizing six forward speeds and one reverse speed has been provided. Yes. One example is the power train disclosed in US Pat. No. 6,071,208.

10 and 11, the conventional power train is formed by combining one double pinion planetary gear set PG1 and two single pinion planetary gear sets PG2, PG3. The input shaft 2 is fixedly connected to the first planet carrier 4 and variably connected to the third planet carrier 14 and the second ring gear 16 through the second clutch C2, and these act as input elements. The second planet carrier 22 always acts as an output element.
The first ring gear 6 and the third ring gear 8, the second sun gear 12 and the third sun gear 10, the second ring gear 16 and the third planet carrier 14 are fixedly connected to each other, and the first planet carrier is the first clutch C1. Through the first sun gear 18.

The second and third sun gears 12 and 10 that are fixedly connected to each other serve as the first brake B1, the second ring gear 16 and the third planet carrier 14 serve as the second brake B2, and the first and third ring gears 6 and 8. Includes a third brake B3 so that it can selectively act as a fixing element, and the first planetary carrier 4 and the first sun gear 18 that are variably connected are provided with a fourth brake B4 on the first sun gear 18 side.
Therefore, as shown in FIG. 11, the friction elements include the first and fourth brakes B1 and B4 at the first speed, the first clutch C1 and the first brake B1 at the second speed, and the second clutch at the third speed. C2, first brake B1, first and second clutches C1, C2 at fourth speed, second clutch C2 and fourth brake B4 at fifth speed, second clutch C2 and third brake B3 at sixth speed In the reverse gear, the second and fourth brakes B2 and B4 are operated while shifting.

In other words, the conventional power train is realized by combining one double-pinion planetary gear set and two single-pinion planetary gear sets with two clutches and four brakes to achieve six forward speeds and one reverse speed. Yes.
However, since the conventional power train uses six friction elements, there is a problem that the volume and weight are increased.
In addition, as shown in FIG. 6B, the conventional power train can obtain detailed specifications (gear ratios of each planetary gear set) and gear ratios of the respective gear stages. However, as shown in FIG. In a 6-speed automatic transmission with a 1: 1 speed ratio, the first sun gear 18 is more than twice the rotational speed of the input shaft at the 3 forward speeds frequently used during overtaking acceleration. As shown in FIG. 8B, the fourth brake B4, which is a non-actuating friction element, also causes a slip at the same speed, thereby reducing durability.

In addition, excessive slip of the friction element occurs at all shift speeds to reduce durability, and power loss is also caused, so the slip speed of the friction element is generally reduced at the second forward speed to the sixth forward speed. There is a need for improvement in the direction of
In particular, it can be seen that the problem of durability is large because the sum of the slip speeds of the friction elements is excessively large in forward 6.
In addition, as shown in FIG. 9B, when considering the number of planetary gear sets that are involved in power transmission and are responsible for loads, two or more planetary gear sets in forward 5th and 6th speeds are involved in power transmission. As power transmission efficiency decreases, there is a need for a powertrain for an automatic transmission that provides higher power transmission efficiency.
US Pat. No. 6,071,208 JP 2002-122192 A JP 2004-168295 A

The present invention has been made to meet the above-mentioned demands, and the object of the present invention is to combine six planetary gear sets and five friction elements to change the forward 6-speed and reverse 1-speed gears. An object of the present invention is to provide a power train for an automatic transmission that can be realized and made compact by reducing the overall length and weight.
It also improves durability and power loss by suppressing high-speed rotating elements, reducing friction element slip and increasing durability, reducing friction element slip speed, and simplifying the power transmission path. Provide a powertrain that can reduce power consumption.

To achieve the above object, the present invention provides a power train for an automatic transmission that is a combination of a first planetary gear set that is a simple planetary gear set and second and third planetary gear sets that are double pinion simple planetary gear sets. The two planetary gear sets of the first, second, and third planetary gear sets have a pair of operating elements fixedly connected to each other to form a compound planetary gear set having four operating elements. The power train of the automatic transmission generally has seven operating elements, and the seven operating elements always rotate at a reduced rotational speed with a first operating element that always acts as a fixed element. A second actuating element and a third actuating element that always acts as an input element;
A fourth actuating element that selectively acts as an input element receiving the transmission of power of the fixed element or the second actuating element, a fifth actuating element that selectively actuates as the input element and the fixed element, and always the overall output A sixth actuating element that operates as an element and a seventh actuating element that selectively operates as an input element.

  The compound planetary gear set is formed by a combination of the first planetary gear set that is a single pinion simple planetary gear set and the second planetary gear set that is a double pinion simple planetary gear set. The planetary gear sets are sequentially arranged from the rear side of the transmission.

  In the compound planetary gear set, the first planetary carrier of the first planetary gear set and the second planetary carrier of the second planetary gear set are fixedly connected, and the first ring gear and the second planetary gear of the first planetary gear set are connected. The two ring gears of the set are fixedly connected and combined.

  The first planetary gear set includes a first sun gear, a first ring gear, and a first planet carrier as operating members, and the second planetary gear set includes a second sun gear, a second ring gear, and a second planet carrier. The third planetary gear set includes a third sun gear, a third ring gear, and a third planet carrier as the operation members, the first operation element is the third planet carrier, and the second operation element is the second operation element. 3 ring gear, 3rd operating element is 3rd sun gear, 4th operating element is 2nd sun gear, 5th operating element is 1st and 2nd ring gear connected to each other, 6th operating element is connected to each other The first and second planetary carriers and the seventh operating element comprise the first sun gear.

The first actuating element is fixedly connected to the housing, the third actuating element is directly connected to the input shaft, and the fourth actuating element is variably connected to the second actuating element through the clutch and simultaneously to the housing through the brake. Variably linked,
The fifth operating element is variably connected to the housing through the brake at the same time as the input shaft and the clutch, and the seventh operating element is connected to the input shaft through the input shaft and the clutch. And

  The first and second clutches that connect the seventh and fifth operating elements to the input shaft and the first brake that connects the fifth operating element to the housing are disposed on the rear side of the transmission, The third clutch that connects the four operating elements and the second brake that connects the fourth operating element to the housing are arranged on the front side of the transmission.

  In a power train of an automatic transmission that is a combination of a first planetary gear set that is a single pinion planetary gear set and second and third planetary gear sets that are double pinion planetary gear sets, the first and second planetary gear sets The first and second planetary carriers and the first and second ring gears are fixedly connected, the third ring gear and the second sun gear are variably connected and combined, and the third sun gear of the third planetary gear set is combined. Is directly connected to the input shaft, the third planet carrier is directly connected to the housing, the second sun gear is connected to the transmission housing via a brake, and the first sun gear and the first ring gear are each connected to a clutch. The first ring gear is connected to the input shaft, and the first ring gear is connected to the transmission housing via a brake.

The power train of the present invention can achieve a forward 6-speed and a reverse 1-speed gear stage by combining three planetary gear sets and five friction elements, and is compact with a reduced overall length and weight. Can be
It also increases durability by lowering the rotational speed of the operating element at low speed gear stages that are frequently used for acceleration, and by reducing the friction element slip speed and simplifying the power transmission path, As a result, power loss can be minimized.

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

FIG. 1 shows an embodiment of the present invention. A power train of an automatic transmission according to an embodiment of the present invention includes first, 2, 3 planetary gear sets PG1, PG2, PG3 are arranged in combination.
The first planetary gear set PG1 includes a first sun gear S1, a first ring gear R1, and a first planet carrier PC1 that rotatably supports a pinion P1 meshing between the first sun gear S1 and the first ring gear R1. Is composed of a single pinion planetary gear set.

The second planetary gear set PG2 rotatably supports a second sun gear S2, a second ring gear R2, and two pinions P2a and P2b engaged between the second sun gear S2 and the second ring gear R2. It consists of a double pinion planetary gear set including two planet carrier PC2 as its operating member.
The third planetary gear set PG3 rotatably supports the third sun gear S3, the third ring gear R3, and the two pinions P3a and P3b engaged between the third sun gear S3 and the third ring gear R3. It consists of a double pinion planetary gear set including a planet carrier PC3 as its operating member.

  The first, second, and third planetary gear sets PG1, PG2, and PG3 are arranged in the order of the third, second, and first planetary gear sets PG3, PG2, and PG1 from the engine side, and the first planet carrier of the operating members. PC1 and second planet carrier PC2, and first ring gear R1 and second ring gear R2 are fixedly connected to each other. The first and second planetary gear sets PG1 and PG2 form one compound planetary gear set by the fixed connection of the first and second planet carriers PC1 and PC2 and the fixed connection of the first and second ring gears R1 and R2. .

The third sun gear S3 is fixedly connected to the input shaft 100 and always operates as an input element. The first sun gear S1 and the first ring gear R1 are variably connected to the input shaft 100 via the first and second clutches C1 and C2, and operate as variable input elements.
Further, the connecting member 102 that connects the first ring gear R1 and the second ring gear R2 is variably connected to the housing 104 via the first brake B1. The third planet carrier PC3 is fixedly connected to the housing 104 and always operates as a fixed element. The second sun gear S2 and the third ring gear R3 are variably connected via a third clutch C3.

The second sun gear S2 is variably connected to the housing 104 via the second brake B2. An output gear 106 is attached to the second planet carrier PC2 and always operates as an output element.
With the above configuration, the first and second clutches C1, C2 and the first brake B1 are located on the rear side of the transmission, and the third clutch C3 and the second brake B2 are located on the front side of the transmission.

  The power train configured as described above includes the first clutch C1 and the first brake B1 at the first forward speed, and the first clutch C1 and the second brake B2 at the second forward speed, as shown in the operation element table of FIG. The first clutch C1 and the third clutch C3 for the third forward speed, the first and second clutches C1 and C2 for the fourth forward speed, the second and third clutches C2 and C3 for the fifth forward speed, and the first clutch for the sixth forward speed. By operating the second clutch C2 and the second brake B2, and the third clutch C3 and the first brake B1 in reverse, the forward sixth speed and the reverse first speed are realized.

The power train of the present invention as described above is a combination of one single pinion planetary gear set and two double pinion planetary gear sets, the first planet carrier PC1, the second planet carrier PC2, the first ring gear R1 and the first ring gear R1. The two ring gears R2 are fixedly connected to each other, so that they have a total of seven operating elements as shown in FIG.
Accordingly, the first node (N1; first operating element) is the third planet carrier PC3, the second node (N2; second operating element) is the third ring gear R3, and the third node (N3; third operating element). Element) is the first sun gear S1, the fourth node (N4; fourth operating element) is the second sun gear S2, and the fifth node (N5; fifth operating element) is the first and second ring gears R1, R2, The sixth node (N6; sixth operating element) is set as the first and second planet carriers PC1 and PC2, and the seventh node (N7; seventh operating element) is set as the first sun gear S1.

FIG. 3 shows a shift diagram when the gear ratio of each planetary gear set is set as shown in FIG. 6A. The shift process according to this is as follows.
First, at the first forward speed, the first clutch C1 and the first brake B1 operate.
Then, since the first brake B1 operates in a state where the input is performed through the seventh node N7 that is the first sun gear S1, the fifth node N5 acts as a fixed element.
As a result, a first speed line L1 that connects the seventh node N7 and the fifth node N5 is formed. Therefore, the 6th node N6, which is the output element, shifts forward 1st speed while outputting only D1.
At this time, the third planetary gear set PG3 does not affect the formation of the first speed. That is, the third planetary carrier PC3 acts as a fixed element while the input to the third sun gear S3 is performed, but the third clutch C3 is released, so that the third ring gear R3 operates in an idling state. To do.

In the second forward speed, the operation of the first brake B1 is released in the state of the first speed, and the operation of the second brake B2 is controlled.
Then, input is performed through the first sun gear S1 as in the first speed with the fixed element converted to the second sun gear S2. Therefore, a second speed line L2 connecting the seventh node N7 and the fourth node N4 is formed. Therefore, the shift to the second speed is performed while outputting only D2 at the sixth node N6 as the output element.
At this time, the third planetary gear set PG3 does not affect the formation of the second speed as in the first speed. That is, the third planetary carrier PC3 acts as a fixed element while the input to the third sun gear S3 is performed, but the third clutch C3 is released, so that the third ring gear R3 operates in an idling state. To do.

In the third forward speed, the operation of the second brake B2 is released in the state of the second speed, and the operation of the third clutch C3 is controlled.
If it does so, 3rd ring gear R3 and 2nd sun gear S2 will be connected in the state in which input is performed through 1st sun gear S1. At this time, the rotation speed of the engine is input to the seventh node N7, and the rotation speed decelerated through the third planetary gear set PG3 is input to the fourth node N4. Accordingly, the third speed speed line L3 as shown in FIG. 4 is formed at the third speed, and the shift to the third speed is performed while the output of only the D3 is performed at the sixth node N6 as the output element. .

In the fourth forward speed, the operation of the third clutch C3 is released in the state of the third speed, and the operation of the second clutch C2 is controlled.
Then, since input is simultaneously performed through the first sun gear S1 and the first ring gear R1, the first and second planetary gear sets PG1, PG2 are in a directly connected state. Accordingly, a fourth speed line L4 as shown in FIG. 4 is formed, and the first and second planetary gear sets rotate together. Therefore, at the sixth node N6 that is the output element, the shift to the fourth speed is performed while the output of only D4 (that is, the output at the same speed as the input) is performed.
At this time, the third planetary gear set PG3 does not affect the formation of the fourth speed as in the first and second speeds. That is, the third planetary carrier PC3 acts as a fixed element while the input to the third sun gear S3 is performed, but the third clutch C3 is released, so that the third ring gear R3 operates in an idling state. To do.

In the fifth forward speed, the operation of the first clutch C1 is released in the state of the fourth speed, and the operation of the third clutch C3 is controlled.
Then, the third ring gear R3 and the second sun gear S2 are connected in a state where input is performed through the first ring gear R1. At this time, the rotational speed of the engine is input to the fifth node N5, and the rotational speed reduced through the third planetary gear set PG3 is input to the fourth node N4. Therefore, the fifth speed line L5 as shown in FIG. 5 is formed at the fifth speed, and the output of the sixth node N6, which is the output element, outputs only the D5 overdrive state to the fifth speed. Shifting is performed.

At the sixth forward speed, the operation of the third clutch C3 is released in the state of the fifth speed, and the operation of the second brake B2 is controlled.
Then, the second sun gear S2 acts as a fixed element in a state where input is performed through the first ring gear R1 that is the fifth node N5. Therefore, at the sixth speed, as shown in FIG. 5, a sixth speed line L6 connecting the fourth and fifth nodes N4 and N5 is formed, and at the sixth node N6 which is an output element, an overdrive of only D6 is formed. The shift to the sixth speed is performed while the state is output.
At this time, the third planetary gear set PG3 does not affect the sixth speed, like the first, second and fourth speeds. That is, the third planetary carrier PC3 acts as a fixed element while the input to the third sun gear S3 is performed, but the third clutch C3 is released, so that the third ring gear R3 operates in an idling state. To do.

In the reverse gear, the third clutch C3 and the first brake B1 are controlled.
Then, the third ring gear R3 and the second sun gear S2 are connected in a state where the first and second ring gears R1, R2 operate as fixed elements. Therefore, the rotational speed decelerated from the planetary gear set PG3 is input to the fourth node N4, and a reverse speed line Lr connecting the fourth, fifth nodes N4 and N5 is formed at the reverse speed as shown in FIG. Is done. At the sixth node N6, which is an output element, a reverse shift is output while only R is output, and a reverse shift is performed.

6A and 6B, FIG. 7A and FIG. 7B, FIG. 8A and FIG. 8B, and FIG. 9A and FIG. 9B are the operations when operating the powertrain of the automatic transmission according to the embodiment of the present invention and the prior art. The status is charted to facilitate comparison.
That is, FIG. 6A and FIG. 6B show the gear ratio of each planetary gear set of the power train according to the embodiment of the present invention and the prior art, and the gear ratio of each shift stage, respectively. The gear ratio is set so that the gear ratio equivalent to the gear ratio of each gear stage can be realized.

7A and 7B are diagrams in which the rotational speeds of the respective operating elements with respect to the input rotational speed are arranged according to the shift speeds in the embodiment of the present invention and the prior art. 8A and 8B are tables showing the results of calculating the slip speeds of the non-actuating friction elements for the respective shift speeds in the embodiment of the present invention and the prior art. FIG. 9A and FIG. 9B relate to the embodiments of the present invention and the prior art, in which planetary gear sets that are involved in power transmission and are responsible for loads are arranged for each shift stage.
6A to 8B can be easily calculated by those skilled in the art from the powertrain configuration and operation table according to the embodiment of the present invention and the prior art.

Referring to the drawings, the power train according to the embodiment of the present invention is compared with the power train according to the prior art. In the power train according to the embodiment of the present invention, the third frequently used during overtaking acceleration is used. It can be seen that there is no friction element that rotates faster than the input shaft at high speed (see FIG. 7), and the slip speed of the non-actuating friction element is also less than the rotation speed of the input shaft (see FIG. 8).
As can be seen from FIGS. 8A and 8B, the automatic transmission power train according to the embodiment of the present invention generally has a frictional element slip at the forward shift stage as compared with the conventional automatic transmission power train. The speed is small.
9A and 9B, the power train of the automatic transmission according to the embodiment of the present invention has the number of planetary gear sets involved in power transmission for shifting at a plurality of shift speeds according to the prior art. Less compared to the powertrain, thereby providing higher power transmission efficiency.

  The preferred embodiments related to the present invention have been described above, but the present invention is not limited to the above-described embodiments, and includes all modifications within the scope of the technical scope to which the present invention belongs.

1 is a configuration diagram of a power train according to an embodiment of the present invention. 3 is an operation table of a power train according to an embodiment of the present invention. FIG. 3 is a shift diagram of forward and first speeds of the power train according to the embodiment of the present invention. FIG. 5 is a shift diagram of forward and third forward speeds of the power train according to the embodiment of the present invention. FIG. 5 is a shift diagram of forward, sixth and reverse speeds of the power train according to the embodiment of the present invention. A is a chart showing an example of a gear ratio of a power train of an automatic transmission according to an embodiment of the present invention. B is a chart showing an example of a gear ratio of a power train of an automatic transmission according to a conventional technique. A is a chart showing the rotational speed of each friction element of the power train of the automatic transmission according to the embodiment of the present invention. B is a chart showing the rotational speed of each friction element of the power train of the automatic transmission according to the prior art. A is a chart showing slip speeds of non-actuating friction elements of a powertrain of an automatic transmission according to an embodiment of the present invention. B is a chart showing slip speeds of non-actuating friction elements of a powertrain of an automatic transmission according to the prior art. A is a chart showing a power transmission path of a power train of an automatic transmission according to an embodiment of the present invention. B is a chart showing a power transmission path of a power train of an automatic transmission according to the prior art. 1 is a diagram illustrating an example of a power train of an automatic transmission according to a conventional technique. FIG. 11 is an operation element table of the power train according to FIG. 10. FIG.

Explanation of symbols

100 Input shaft 102 Connecting member 104 Housing 106 Output gears PG1, PG2, PG3 1st, 2nd, 3rd planetary gear set PC1, PC2, PC3 1st, 2nd, 3rd planet carrier R1, R2, R3 1st, 2nd, 3rd ring Gears C1, C2, C3 Third clutch B1, B2, B3, B4 First, second, third, fourth brake N1 to N7 First to seventh nodes S1, S2, S3 First, second, third sun gear

Claims (8)

In the power train of an automatic transmission that combines a first planetary gear set that is a simple planetary gear set and a second and third planetary gear set that is a double pinion simple planetary gear set,
Two planetary gear sets of the first, second and third planetary gear sets form a compound planetary gear set having four operating elements by two pairs of operating elements being fixedly connected to each other. The power train of the automatic transmission has seven operating elements as a whole,
The seven actuating elements are:
A first actuating element that always acts as a fixing element;
A second actuating element that always rotates at a reduced rotational speed;
A third actuating element that always acts as an input element;
A fourth actuating element that selectively acts as an input element that receives the power of the fixed element or the second actuating element;
A fifth actuating element that selectively actuates as an input element and a fixed element;
A sixth actuating element that always operates as an overall output element;
A seventh actuating element selectively actuated as an input element;
A six-speed power train for an automatic transmission for a vehicle, comprising:   The compound planetary gear set is formed by a combination of the first planetary gear set, which is a single pinion simple planetary gear set, and the second planetary gear set, which is a double pinion simple planetary gear set. Item 6. A six-speed powertrain of the vehicle automatic transmission according to item 1.   The six-speed power train of an automatic transmission for vehicles according to claim 2, wherein the first, second and third planetary gear sets are sequentially arranged from the rear side of the transmission. The compound planetary gear set is
The first planet carrier of the first planetary gear set and the second planet carrier of the second planetary gear set are fixedly connected,
The automatic transmission for a vehicle according to claim 1 or 2, wherein the first ring gear of the first planetary gear set and the two ring gears of the second planetary gear set are fixedly connected and combined. Fast powertrain. The first planetary gear set includes a first sun gear, a first ring gear, and a first planet carrier as operating members,
The second planetary gear set includes a second sun gear, a second ring gear, and a second planet carrier as operating members,
The third planetary gear set includes a third sun gear, a third ring gear, and a third planet carrier as operating members,
The first actuating element is the third planet carrier,
The second actuating element is a third ring gear,
The third actuating element is the third sun gear,
The fourth actuating element is the second sun gear,
The fifth actuating element is a first and second ring gear fixedly connected to each other;
The sixth actuating element is a first and second planet carrier fixedly connected to each other,
The seventh operating element is the first sun gear,
The 6-speed power train of the automatic transmission for vehicles according to claim 1 characterized by comprising. The first actuating element is fixedly coupled to the housing;
The third actuating element is directly connected to the input shaft,
The fourth operating element is variably connected to the second operating element through a clutch and at the same time is variably connected to the housing through a brake.
The fifth operating element is variably connected to the housing through the brake at the same time as the input shaft and the clutch.
6. The six-speed power train of an automatic transmission for vehicles according to claim 1 or 5, wherein the seventh operating element is connected to the input shaft through an input shaft and a clutch. The first and second clutches that connect the seventh and fifth operating elements to the input shaft and the first brake that connects the fifth operating element to the housing are arranged on the rear side of the transmission,
The third clutch for connecting the second operating element and the fourth operating element and the second brake for connecting the fourth operating element to the housing are arranged on the front side of the transmission. 6-speed powertrain for vehicle automatic transmissions. In the power train of an automatic transmission that combines a first planetary gear set that is a single pinion planetary gear set and a second and third planetary gear set that is a double pinion planetary gear set,
The first and second planetary carriers of the first and second planetary gear sets are fixedly connected to the first and second ring gears respectively, and the third ring gear and the second sun gear are variably connected and combined,
The third sun gear of the third planetary gear set is directly connected to the input shaft;
The third planet carrier is directly connected to the housing,
The second sun gear is connected to the transmission housing via a brake,
The first sun gear and the first ring gear are connected to the input shaft via a clutch,
A 6-speed power train of an automatic transmission for a vehicle, wherein the first ring gear is connected to a transmission housing via a brake.

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